cases2004, leg 5 (0402) - université lavalcases.quebec-ocean.ulaval.ca/cases0304_leg5_cruise... ·...

$: CASES2004, Leg 5 (0402) - Université Lavalcases.quebec-ocean.ulaval.ca/CASES0304_leg5_cruise... · the file 'operator_verbose_log_0402.doc' (\Shares\Rosette\Leg5). Ninety profiles$
CASES2004, Leg 5 (0402)

CCGS Amundsen Cruise Report

18 February to 31 March Specific Activities 1. Report on the activities of the rosette operator Participant: Mykola Vysotskyy My activities consisted mainly in sampling two CTD profiles daily at 12-hour interval (at 06:30 and 18:30) in order to follow the seasonal evolution of the water column while the ship was stationary in the ice at 70° 02.71' N 126° 18.06' W, and in providing biologists and chemists with the volumes of water they requested at specified depths. Other activities consisted in a fortnightly (in this context one week = 6-day cycle) sampling aiming at following the evolution of the content in O18 (not for on board analysis), and weekly sampling for control of the conductivity and dissolved oxygen probes. The SeaBird CTD/rosette worked without any major problem. Very few minor flaws are mentioned in the file 'operator_verbose_log_0402.doc' (\Shares\Rosette\Leg5). Ninety profiles were recorded, and a number of bottles were fired for 62 of those casts. A list of the casts with date, time, type of cast and simultaneous meteorological conditions is given in the file 'ctdlog_0402.xls' (\Shares\Rosette\Leg5). Meteorological data were taken from the bridge just before or just after each cast. Meteorological logbook can be found in the file 'Meteo_Logbook_0402.doc' (\Shares\Rosette\Leg5). The data for 'Cloud Cover' column were taken from Jim Butler’s observations. He was meteorologist on board for leg 4 and 5. All his data can be found in \Shares\Met_Obs folder. Plots of the downcasts are provided in the folder '\Shares\Rosette\Leg5\screenplots'. Information on the utilisation of the sampled water and average values around the closing time of each bottle can be found in the folders ‘\Shares\Rosette\Leg5\rosettesheets’ and ‘\Shares\Rosette\Leg5\btl_files’. The O18 sampling followed a strategy expressed by Robie McDonald in a message to Emmanuelle Rail (rosette operator for Leg 3), i.e. samples collected every two weeks at depths so that the features of the water column are resolved. O18 samples were collected three times (at every second 6-day cycle) at nine depths, and with higher resolution in the upper part of the water column since O18 is used as a tracer for river runoff. In addition, near surface samples were collected from the ice cover just below the ice-water interface. At all depths, water for determination of the salinity was also sampled. Samples for a precise determination of the salinity were also collected at every day 1 of the 6-day cycle at the same depths where samples for chemical analysis were taken. The processing of these samples has not been done so far due to the absence of the salinometer Autosal Guildline s/n 67518, which has been taken to Guideline for inspection. It’s supposed to be shipped back for the next Leg 6.

The determination of the content in dissolved oxygen by titration has been done weekly for controlling the performance of the oxygen probe SBE 43. Results have shown that the values obtained via titration are slightly higher than those obtained from the probe (differences ranging from ~ 0.08 % to 12,2 %, and averaging ~3.8%). Our results are very similar to those obtained during Leg 2 and Leg 4, that is to say the last leg when this instrument was used (see figure below). It seems however that for samples with a relatively high content in dissolved oxygen, the probe values depart now a little more from a perfect match.

. Figure 1 Dissolved oxygen probe performance control. Recommendations: A problem was encountered when the left hand of a cable guide in the moonpool fell into the water (Rosette was not damaged) due to the imperfection of its construction. This imperfection is experienced, as the stopper holding the left side cable guide in place does not cover its full rotation. Therefore, when pulling the left side guide towards the cable, one must be careful as the holder does not have any stopper when rotated past the cable. Past this point, the cable guide will fall into the water and be stopped only by the rosette. 2. Ice-Atmosphere Interactions and Biological Linkages 2.1. Under-ice sediment traps and Ice algae Participants: Bernard LeBlanc, Andrea Riedel and Thomas Juul-Pedersen Collaborators: Marek Zajaczkowski, Wojtek Moskal, Tara Businski and Shinya Yamamoto This 5th leg of the CASES project involved 3 participants and 4 foreign collaborators. The participants were Andrea Riedel and Thomas Juul-Pedersen, PhD students of Michel Gosselin (ISMER Rimouski)

and Christine Michel (DFO Winnipeg), and Bernard LeBlanc, Research Assistant from DFO Winnipeg. Thomas, newly arriving from Denmark 2 weeks before the Leg 5 scientific mission, just started his PhD on the production, in situ concentration and sedimentation rate of zooplankton fecal pellets, while Andrea, from Winnipeg, who was on Leg 1 previously, started her PhD last September and is looking at trophic interactions of heterotrophic protists within the bottom sea ice and at the ice-water interface. Our international collaborators were Marek Zajaczkowski and Wojtek Moskal from the Polish Academy of Science, Shinya Yamamoto from Soka University in Japan and Tara Businski, an American from Memorial University, Newfoundland. A brief description of their implication is mentioned in the sediment trap description section. The objective of this Leg 5 was to assess the sedimentation regime of organic material and ice-algal community. Sedimentation was assessed using fixed under-ice sediment traps, located at Takatuk site, about 1 km south-east of the ship, while the ice-algal community was sampled a few meters north of the same location. The sediment traps were deployed and retreived 4 times and ice algae were sampled 8 times. Description, objectives and preliminary results of project activities Sediment traps The increasing light levels and decreasing ice and snow extend during spring initiate an increase in primary production both in the ice and water column. The increase in primary production has a triggering effect, which can be observed through the entire food web. However, the increase in organic material being assimilated in the food web also means a higher concentration of organic particles subject to sedimentation. Main objective 1: Determine the sedimentation rate of organic material in relation to the different changes in first-year ice and open water periods. Short-term sediment traps were deployed every 8 days at 1, 15, 25 and 180 m from the underside of the ice. The sediment trap arrays included two parallel lines with sediment traps at 1, 15 and 25 m and a third line with duplicate 180 m sediment traps. An additional sediment trap was added at 50 m on the third line, which was turned over to Tara Businski, working for Don Deibel, upon recovery. Subsamples from the 1, 15, 25 and 180 m sediment traps were takenfor later analyses of the following parameters: Parameters Chlorophyll a Biosilicate POC/PON PIC DOC EPS (1 m trap only) Faecal pellets Subsamples from the sediment traps were also shared with Marek Zajaczkowski from the Polish Academy of Science for analyses of algal counting and taxonomy and for total material measurements. Shinya Yamamoto from Soka University received subsamples from the 1 m sediment trap for primary production experiments.

Faecal pellets Arctic pelagic ecosystems are characterised by large overwintering copepod species. During early spring they emerge from their diapause and migrate to the euphotic zone, ready to utilise the developing bloom. This distinctive life cycle enable an efficient utilisation of the developing spring bloom. Copepods influence the carbon cycling by packing the egested material into large fast sinking faecal pellets favouring vertical export of carbon. However, they also graze upon the faecal pellets themselves (coprophagy) and studies has shown that a large fraction of the material leaks out of the faecal pellets as dissolved material, this benefits the pelagic microbial community and remineralisation process. To get a better understanding of the copepods role in the carbon export and remineralisation the production rate, concentration in the water column and sedimentation rate is needed. Objective 1: Determine the faecal pellet production rate for two different size groups of copepods. Faecal pellet production experiments were conducted every 7 days, doing 4 replicates of each of the two size groups (200-1000 and >1000 µm). Special experiment containers were constructed allowing the faecal pellets to sink through a mesh bottom out of reach for the copepods. Copepods and faecal pellets were after the experiments preserved for later analyses. Preliminary analyses revealed no faecal pellet production during the start of leg 5. Objective 2: Determine the in situ concentration of the two size groups of copepods above the 25 m sediment trap. Zooplankton tows were conducted every 8 days during the recovery and deployment of the sediment traps at the sampling site. These net tows from 25 to 0 m will later be analysed according to the two size groups of copepods (200-1000 and >1000µm), giving an estimate of the concentration of these size groups in the water column. Objective 3: Determine the concentration of faecal pellets in the water column at all trap depths. Water samples were collected at the sampling site at the 1, 15 and 25 m sediment trap depths, including water from 180 m collected from the ships moon pool, every 8 days parallel to the recovery and deployment of sediment traps. Subsamples of the collected water were concentrated for later analyses of the faecal pellet concentration. Objective 4: Determine the sedimentation rates of faecal pellets at all trap depths. A second sediment trap array was recovered and deployed every 8 days parallel to the previously mentioned array, with the main purpose of supply enough material for estimating the sedimentation rate of faecal pellets at each depth. Knowing the in situ faecal pellet production (combining objective 1 and 2), concentration (objective 3) and sedimentation (objective 4) in the water column make it possible to get a much better understanding of the fate of the produced faecal pellets. Table 2 lists the number of the different samplings during leg 5, and the planned types of sampling during Leg 6-9: Sampling type Leg 5 Leg 6 Leg 7 Leg 8 Leg 9 Faecal pellet production experiments # 5 X X X Zooplankton tows # 2 X X X Water samples # 4 X X X X Sediment traps # 5 X X X X

Ice algae community The ice algae were sampled every 5th day at the far end of Takatuk site. Low and high snow depth sites were assess and a wide array of biological and chemical parameters were measured. Those parameters are; nutrients , DOC, TOC, salinity, pH, total and fractionated (>5um) chlorophyll a, particulate organic carbon and nitrogen (POC-PON), particulate inorganic carbon (PIC), Biosilica, bacteria, flagellates, cell identification and enumeration and EPS. All the methods are described in the leg 2 cruise report, section 2.3 (free drifting sediment traps and newly formed ice) The preliminary results of ice algal biomass indicates a clear increase over time (figure 2). Their is a gradualy slow increase from February 24th to March 5th, after that date it really picked up going from 0.1 to 0.9 mg chl a m-2. These results suggest that enough light is now reaching the underice community, triggering the production of primary producer. Surface water phytoplankton biomass also significantly increased over time, starting at 0.05 mg chl a m-3 on February 24th to 0.2 mg chl a m-3 late March.

Figure 1: Ice algae and surface water phytoplankton at Takatuk site Trophic interactions in sea ice and ice-water inerface The main objective of this research is to describe trophic interactions of heterotrophic protists within the bottom sea ice and at the ice-water interface. For each ice and ice-water interface sample collected during leg 5, the protist and bacteria assemblages were quantified using epifluorescent microscopy. Three different experiments were also conducted on each ice and water sample to determine protists bacterivory (FLB grazing experiments), ammonium regeneration by protists, and ammonium (15N-NH4) uptake by eukayotic and prokaryotic cells. The experiments were conducted every five days, on the day following ice core sampling. Experiments were also conducted on two ice and water samples collected from the Angaguk site. Ammonium samples were analyzed on board whereas the 15N-NH4

samples were stored for later analysis by mass spectroscopy. For the grazing experiments, flow cytometry samples were frozen for later analysis and microscope slides were prepared for epifluorescent examination. Preliminary results from the FLB grazing experiments, indicate that there is limited bacterivory in the ice and interface water. However, there has been a gradual increase in ammonium concentration in ice under low snow conditions suggesting an increase in heterotrophic activity. Ammonium concentrations are also consistently higher within the ice as compared to the interface water. Aknowledgments The members of our team would like to express their sincere congratulations to a great leadership and diplomatic work showed by our chief scientist, Jody Deming. Many thanks Jody, we love you and will miss you a lot. Cheers Bernard LeBlanc Andrea Riedel Thomas Juul-Pedersen 2.2 Surface meteorology /exchanges & Satellite validation Cruise participants: C.J. Mundy, Christina Blouw, Jim Butler, Carrie Breneman, Steve Howell, Randy Scharien, Mark Gordon, Chris Konig

Introduction Physically, an ice cover prevents the direct exchange of energy, mass and momentum between the atmosphere and ocean, thereby impacting physical, chemical and biological processes within both the ocean and atmosphere. Itself, the snow and ice cover is a complicated mixture of ice, water, air, brine, salts and biota, whose proportion and characteristics both affect and are affected by air-sea coupling and biogeophysical processes within both the atmosphere and ocean. The overarching objectives of our sub-group examine different aspects of these relationships and over a variety of space and time scales. The participants of leg 5 established new monitoring facilities and locations for snow distribution and satellite validation while maintaining the sampling schedule and data collection facilities set up in previous legs. Among the parameters measured were meteorological parameters like temperatures, wind, humidity and radiation as well as fluxes of heat, water vapour, momentum and carbon dioxide, blowing snow properties, snow and ice geophysical properties and electromagnetic interaction, snow and ice chemistry and topographic snow and sea ice macro-feature characterization for satellite validation and bear habitat studies.

In the organization of this report we separate these activities into discreet sections, even though the research is highly integrated and collaborative.

Site Locations Time series sampling was conducted on-board the CCGS Amundsen (70° 2.516’ N, 126° 15.894W) and at sites distributed within 1.5 km of the ship (Figure 1). All sites were on a pan of uniformly

consolidated seasonal sea ice that ranged in thickness from approximately 120 cm (at the start of Leg 5) to 165 cm (by the end of the Leg). Snow cover consisted on 5 to 10 cm of hard-packed snow covered with moving snowdrifts of varying thickness. Distributed sampling for topographic snow and ice macrofeature characterization occurred at sites within approximately 10 km of the ship. The specific locations and nature of the samplings is described in the respective sections below.

Figure 1. The location of sampling sites in close proximity to the CCGS Amundsen.

Micrometeorology and Surface Exchanges of Energy, Momentum and CO2

A number of posts and towers were installed along a surveyed north-south transect starting at approximately 250 m south of a parcol shelter at Takatuk (Site F in Figure 1). The arrangement of these structures is shown in Figure 2. The two 10m masts and a cluster of instrumented posts in the foreground of the photograph are associated with a blowing snow experiment. GPS determined locations of the two 10m masts are N 70 02.542 W 126 15.894 and N 70 02.532 W 126 15.894. The southern-most structures (i.e., the tower-antenna towers – one 6m and the other 2.5m) are equipped to monitor the components of the heat and radiation budget and the atmospheric CO2 flux (Lat-Lon of 70° 2.516’N, 126° 15.894’W). For the purpose of this report, the equipment and dataset associated with the blowing snow project and the surface fluxes (heat, radiation and CO2) will be described in separate subsections.

Meteorology and Boundary Layer Profiling (Jim Butler, C.J. Mundy, Chris Konig) Monitoring can be divided into four categories, automated monitoring of near-surface meteorological elements, manual observations of weather, boundary layer profiling for wind, temperature and humidity structure and cloud viewing.

Automated Station(s)

A 10 m tower was installed on the foredeck of the Amundsen during Leg 1 of the CASES cruise. Originally, this tower supported a ship-based eddy correlation system and sensors to monitor the basic meteorological elements, air temperature, relative humidity, wind speed and direction and atmospheric pressure, in addition to incident solar and long-wave radiation. At the start of the leg, the eddy correlation system was removed from the tower, but the basic monitoring of surface meteorology was continued for continuity, despite the fact that all, but atmospheric pressure are being monitored at research stations on the ice. Data are stored as one-minute averages. The AVOS system onboard the Amundsen also automatically collects temperature, sea surface temperature, relative humidity, wind speed, wind direction, and barometric pressure and transmit these data every five minutes past the hour to a weather station on land through the Inmarsat-C transceiver. Two visibility sensors (EnviroTech®, model SentryTM) were mounted at 1.5m and 3.5m among meteorological and flux measuring equipment near to Takatuk (Figure 1). Data are being logged at 10 minute intervals on a Campbell Scientific data logger (model CR23X).

Hourly Meteorological Observations Using the AVOS system available on the Amundsen, at each hour the date, time, station, RH, air temperature, sea surface temperature, wind direction and speed are documented. Due to ice accretion on the AVOS system anemometers, actual wind speed was obtained by using the ships own anemometers. Wind direction was still obtained from the AVOS system. Manual observations of total cloud cover, cloud height, opacity, visibility, precipitation amounts, current weather, and water vapor in the air were also taken. Observations were made at least 14 hours a day for most of this leg. Precipitation is measured using a gauge and Nipher shield that is mounted on top of the wheel-house. Visibility measurements are made onboard the Amundsen using a a Mars II visibility sensor mounted on top of the wheel-house. Calibration multipliers allow the conversion of backscattered light emitted from the sensor to horizontal visibility in nautical miles.

Cloud Height and Amount Clouds play an important role in modulating the incident solar radiation and augmenting the downwelling atmospheric infrared radiance. Measurements of cloud height and atmospheric optical depth were and are measured from a Vaisala® CT25K laser ceilometer. This information is used to infer cloud types for manual observations. Data recording was interrupted once a week to back up the data onto a storage disk. An all sky camera was mounted on the top of the bridge. This is a video camera directed downwards to a hemispheric mirror that provides a view of the entire sky. The images are recorded for daylight conditions on a time-lapse video recorder at ~17s intervals. These images will be analyzed later to determine cloud type and cloud fraction.

Atmospheric Profiling Total atmospheric column precipitable water estimates are available from a microwave radiometer (Radiometrics®, model WVR-1100). This radiometer receives microwave radiation from the sky at 23.8 GHz (K band) and 31.4 GHz (Ka band). Data collection was interrupted once a week to back up the data onto a storage disk. Radiosondes were launched (relative humidity, wind speed and direction) on a scenario specific basis. Some were launched at 00:00Z and 12:00Z on clear days to aid with arctic weather forecasting by Environment Canada, and also to provide a baseline for further launches under different weather conditions. The times were later shifted to 23:00Z and 11:00Z to guarantee that the data was obtained and sent to Environment Canada's offices in time to be included with model runs. Other launches were associated with specific meteorological events. The frequency of balloon launches ranch from every 6

to every 3 hours, depending on what was deemed necessary to obtain an accurate record of the event. Decisions regarding the sampling frequency were made by John Hanesiak at the University of Manitoba, based on forecast information unavailable to ship personnel. A SODAR system (Remtech®, model PA1) was also installed near to Takatuk. The sounder derives vertical wind profiles to great heights by processing space-time information on returned echoes from emitted sound waves.

Blowing Snow (Mark Gordon) Mark Gordon continued the upkeep and maintenance of the two 10m meteorological posts, installed on leg 4 about 200m S of the Takatuk parcol and generator (see Figure 2). On 18 Feb a spread spectrum radio (RF400) was added to the second tower. Data are stored at both towers as 5-minute averages and were transmitted via the spread spectrum radios to the ship at 0003Z and 1203Z each day. Due to problems with transmission, in the last week of the leg, the data was collected via manually initiated radio transmission once every day. This system continues to work very well. With the exception of a few bad data (less than 0.01%), all of the previously installed instruments operated without problems. Data loggers (CR10X on post 1 and 23X on post 2, both have lead acid battery packs plus battery chargers in CR12/14 enclosures mounted at about 1m. The enclosures include 40W light bulb as heaters – these can be replaced by 100W heating elements and put through Thermocube outlets to limit operation to switch on below 2C and off at 7C if desired. At –30C air temperature the 40W bulbs are on continuously and hold the data logger panel temperatures at about –12C. Instrumentation on the two 10-m posts, and ancillary posts is as follows, Post 1: Windmonitor (wind speed and direction) at 10m, Gill cup anemometers at 4m, 2m and 1m for determining the wind profile. The lower 2 anemometers are on a stand-off 2m post to avoid flow distortion around the data logger enclosure. A CSI Temperature Humidity sensor in a 12-plate radiation shield is installed at 1.5m and a thermocouple pair, in 6-plate radiation shields at 9.5m and 1.5m for delta-T. A CSI Sonic Ranger, SR50 snow depth sensor is at approximately 2m, and, for blowing snow, an infra-red particle counter is mounted at 0.5m on the stand-off post. Post 2: Windmonitor at 10m plus a cup anemometer at 1m on a stand-off post, 6 thermocouples (in the water below the ice, at the ice/snow boundary, and in the air at 0.5m, 1.5m, 4m and 9.5m in 6-plate radiation shields. Temperatures are referenced to the data logger panel temperature, measured by a built-in thermistor. 3 particle counters (2m, 1m, 0.2m) are installed on the stand-off post for blowing snow measurements. A “Special Combox” for processing data from a FlowCapt blowing snow sensor is mounted at about 1m and the sensor itself is a tube, mounted about 50 cm from the post from 0.1 to 1.1 m above the snow surface. Two Sentry Visibility Sensors, #1 at 1.5m, #2 at 3.3m, are on separate posts approx 10 m away from post 2. These have separate 120VAC power supplies but data from them are processed and recorded on the CR23X.

Figure 2. Instrumented towers and masts along a north to south transect (looking south) approximately 250 m south of Takatuk. (Photo by O. Owens)

Tim Papakyriakou (U of M) has additional towers nearby with eddy correlation flux measurements, wind speed, 4 component radiation and an ice temperature profile. There was also a Doppler SODAR system (John Hanesiak group, U of M) at the Takatuk site (removed 25 Mar), approximately 50m S of the parcol . An Electric Field Meter was added to a 2m post located 15m west of Post 2 on 20 Feb. This instrument was used to measure the electric gradient near the snow surface. The data module for the Field Meter was mounted in a CR8/10 enclosure mounted on the eastern visibility sensor post and the data was recorded on the CR23X on Post 2. The instrument was calibrated by placing a known voltage at a fixed distance beneath the meter and measuring the output signal. In the field the instrument calibrated significantly lower. Attempts were made to regulate the temperature inside the CR8/10 enclosure using insulation, a thermocube, and light bulb or 100W heater. This had varying results, generally working only at outside temperatures above -25C. It is hoped to fix this problem on Leg 6 by replacing the thermocube with a controllable thermostat. Three blowing snow traps were installed on the visibility sensor posts on 26 Feb. The traps are mounted at heights of 75cm, 150cm, and 210cm. These traps are emptied after blowing snow events, the snow is melted and the volume of water measured to give the mass flux of blowing snow at each trap (assuming a water density of 103 kg m-3 ) . Additionally, an automated camera was installed at various sites near the parcol to record images of blowing snow. Recordings were made during blowing snow events in batches of 1000 images of 1024x1280 pixels. As well as daylight recordings, the camera was programmed to acquire at regular

intervals overnight. These images will be processed to determine number density, size distribution, and velocity of blowing snow particles.

Snow Depth and Density In addition to the automatic collection of data, surface level snow, 3 or 4 samples were taken on most days with samplers of volume 66cm3. Snow samples were allowed to melt, water volume measured and assumed to have density 103 kg m-3 in order to determine snow density. Densities ranged from about 100 to 450 kg m-3 depending on snow conditions. Snow depths were also measured every two or three days at up to 20 locations around the towers. Depths ranged from 4 to 35cm.

Selected data Data in Figure 3 are selected to give basic information on wind, temperature and humidity, and blowing snow events. Additional data are available from Peter Taylor ([email protected]) if required. Note that only preliminary quality control has been applied at this stage, and the particle counter data in particular should be regarded as qualitative only.

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March 1 Figure 3. Selected data on wind speed and direction, temperature, humidity, and snow depth (red line on left, in cm.) from the Takatuk meteorological posts obtained during CASES leg 5. Particle counts in red are from the post 1 sensor at a height of 0.5m.

Surface Fluxes

(C.J. Mundy and Chris Konig)

Radiation Exchange and Surface Budget

Net all-wave radiation and its components (including incident PAR) were measured at Takatuk (Figure 4). Sensor type and manufacturer are itemized in Table 1. Sensor output was scanned at 3-second increments and stored as 10-minute averages by a Campbell Scientific (model 21X) data logger. AC power to the site powered the logger. Data are available from Jan. 23 onwards. A damaged cable delayed the deployment of reflected surface solar radiation until Feb. 4.

Down facing radiometers were directed toward the west. The extension arm suspending these radiometers could not be oriented toward the south, because the small tower is positioned along the N-S pedestrian line and tracks would be present in the sensor FOV. A quantum sensor was also deployed flush with the ice surface (under the snow) approximately 10 m east of the radiation tower.

Figure 4. Radiation measurement assemblage south of Takatuk (Photo by Owen Owens).

Heat Exchange The instrumentation associated with heat, water vapour, momentum and CO2 exchange studies budget is depicted in Figure 5 and itemized in Table 1. An eddy correlation system (Figure 6), consisting of a Campbell Scientific sonic anemometer (CSAT3) and LICOR open-path H2O/CO2 infrared gas analyzer (LI7500), was mounted at 4.35 m above the ice surface and oriented to face 190° from north. Sensor output were scanned at 10Hz by a Campbell Scientific data logger (model 23x) and the raw, high frequency, data were transmitted to the CCGS Amundsen by RF telemetry in ten minute intervals. The radio frequency transmitter was maintained above its threshold temperature of –25° by a 60W light bulb that was housed within the logger enclosure.

Other sensors on the tower (anemometers, temperature/relative humidity probes, IR transducer) were scanned at 3s increments by a Campbell Scientific data logger (model 10x). Temperature-relative humidity sensors were oriented to the north, while anemometers faced south. The offset for the zeroing of the wind vane (on top of the tower) is –16.7°. Data are available from Jan 22 onwards.

Figure 5. The 6 m heat budget tower south of Takatuk.

Ice temperature was continually measured at 10 locations (Table 1) extending from the ice surface to 1m depth from the surface by thermocouple sensors (24 AWG, Type T) imbedded into a 4.08 cm O.D. PVC tube. The sensor junctions were embedded in high conductivity epoxy and inserted into PVC plugs, which were themselves inserted into the PVC tubing so that the sensor tips were flush against the ice wall. Snow temperature was measured at 15 locations at 1.5 cm increments up from the snow base by thermocouple sensors (24 AWG, Type T) that were themselves embedded within 5/32” brass tubes, each 8 cm in length. The snow sensor array (Figure 7) was installed immediately adjacent to the ice temperature string.

Figure 6. The eddy correlation system (CSAT3 and LI7500) on the heat budget tower.

Table 1. Parameters monitored in association with the heat budget and radiation tower. a) atmospheric sensors Variable measured Sensor Manufacturer (model) Height from ice

(m) horizontal wind speed and direction wind monitor - RM Young® (model

05106 MA) 6.31

horizontal wind speed 3-cup anemometer, Met-One® (model 013a)

1.7, 5.20

temperature and relative humidity Vaisala (model HMP45C 1.6, 5.12? global radiation and reflected short-wave

Eppley® pyranometer (model PSP) TBD ~ 2.2 & 1.8

down-welling and surface emitted long-wave radiation

Eppley® pyrgeometer (model PIR) TBD ~ 2.2 & 1.8

net radiation REBS® Q*7 TBD ~ 1.8 PAR irradiance LI-COR® quantum sensor (LI-190) TBD ~ 2.2 Surface Temperature Everest® IRTransducer (Model 4000.4

GL) TBD ~ 2.2

CO2 and H2O concentration open path IRGA LI-COR® (model LICOR LI-7500)

4.36

wind vector (x, y, and z coordinates) sonic anemometer – Campbell Scientific®, CSAT3

4.36

b) snow and sea ice Variable measured Sensor Manufacturer (model) Position snow temperature thermocouple sensors (24 awg – type T) 15 sensor at 1.5 cm

increments starting at 0.5 cm

ice temperature thermocouple sensors (24 awg – type T) -1 cm,-5,-10,-15,-20,-30,-40,-50,-60,-70,-80,-100

PAR transmission (through snow) quantum sensor (LI-192) undersnow ~-8 cm

Figure 7. Snow temperature array. Note, sensor spacing in the figure is 3 cm, not 1.5 cm spacing, as used during the CASES’ experiment.

Spectral Albedo and Transmission (C.J. Mundy and Chris Konig) Spectral measurements of albedo and transmission through the snow cover were made to characterize the optical properties of the snow cover for the improvement of radiative transfer models of the snow cover. Measurements were made using a dual head Analytical Spectral Device© spectral radiometer which measures 512 bands within the visible and near infrared range. Eight conduits, 9ft in length, were successfully installed at various sites near Takatuk (Figure 1). These conduits were embedded into the ice, with a port access on one end and the other end open to the snow cover as shown in figure 8. A fiber optic cable with a reverse cosine receptor was fed down the conduit to measure the transmission of spectral radiation through the snow cover at the end of the conduit. Spectral albedo was also measured at each site, along with a reading of snow depth from a measurement dowel installed at the end of the conduit. As the spectral radiometer computer did not operate well below -25°C, measurements were restricted to 3 dates during leg 5. The intention is to continue this sampling throughout leg 6.

Figures 8. Picture and set up of the snow conduits used for spectral transmission measurements. (Photo: Chris Konig)

Carbon Flux Atmospheric

Atmospheric CO2 concentration was continuously measured using a LI-7500 open-path sensor as part of the eddy correlation system (described above) that was mounted on the heat budget tower (Figure 5). Similarly, eddy correlation estimates of the atmospheric CO2 flux can be derived using the system. Information on the associated sampling of those ice and ocean pCO2 and parameters affecting pCO2 are reviewed below. In-situ measurements of pCO2 concentration were made following procedures outlined by Kammann et al., (2001) 1. Probes consisted of silicone tubing closed with silicone septa on both ends and were installed within a PVC tubing (Figure 9). Each PVC tube contained three probes, one between 20-40cm, the other between 60-80 cm and the third between 100-120 cm, thereby stratifying the ice into 20 cm sections. In theory, molecules, such as CO2, CH4 and O2, would diffuse across the porous, semi-permeable membrane allowing the air space within the silicone tube to approach an equilibrium level 1 Kammann, C., L. Grunhage, and H.-J Jager, (2001), A new sampling technique to monitor concentrations of CH4, N2O and CO2 in air at well-defined depths in soils with varied water potential. Eur. J. Soil Sci., 52, 297-303.

with the surrounding sea ice. Air was drawn from these probes every second day by syringe through 1/8” tygon tubing and immediately injected into evacuated 10 ml vials for analysis on gas chromatograph. Six PVC probes were installed, three near to Takatuk and three in close proximity to the ship. Silicone probes were also installed into seawater immediately beneath the sea ice cover. For detailed information about the measurements taken refer to Lisa Miller’s cruise report (subproject 2.6)

Figure 9. Gas sampling probes that were used for in-situ pCO2 determination.

Snow and Ice Geophysics (C.J. Mundy, Christina Blouw and Chris Konig)

Snow geophysics Snow microstructure The main objectives of the snow microstructure research are to: a) understand the nature of physical and thermodynamic changes which occur within a natural snow cover on sea ice over a full annual cycle, b) understand the links between thermodynamic evolution of the system and brine and water migration within the snow volume; and c) investigate ways of exploiting the brine-temperature relationships examined in (b) for retrievals of snow related geophysical or thermodynamic state from microwave emission and scattering. To accomplish these objectives, a comprehensive dataset of physical, thermodynamic and electromagnetic (see Snow Electromagnetic section) properties of snow over sea ice has been acquired at various sites throughout leg 5. The following data were collected at each site:

- Snow Depth

- Temperature (using a temperature probe Hart Scientific Model 1522)

- Density (using density cutter’s samples and a scale)

- Salinity (using a salinometer Hoskin Scientific Cond 330i)

- Wetness (using a capacitance plate)

- Snow grain size (using a Canon Powershot G2 4.2 megapixels)

- Snow grain structure (using Canon Powershot G2 4.2 megapixels and silicone oil)

- Snow water equivalent SWE (by computing thickness and density)

Three time series sites were monitored during leg 5, the side of the ship and Takatuk (Micrometeorological site and ice coring site). Snow pits under both a thick and thin snow cover were sampled every 3-4 days at the side of the ship throughout leg 5, continuing sampling accomplished during legs 3 and 4. At Takatuk, daily snow pits at the Micrometeorological site were collected under a thin (non drifted – approximately 4-8cm thickness) and thick (a single snow drift – approximately 14-16cm thickness) snow cover from March 7 through March 30, 2004, with the intention to carry on into leg 6. At the ice coring site, a snow pit was collected once a week in conjunction with the weekly ice core collection. On March 26, 2004, a transect of snow pits every 5m over 50m and every 25m over an additional 50m (13 snow pits in total) was collected. This was accomplished to examine spatial variability of snow properties. The snow pit transect was collected within the first 100m of a 500m transect of snow depth and ice thickness measured every 0.5m near the Appun site (Figure 1). Snow Macrostructure Macro scale snow distribution was investigated over various types of sea ice, over sea ice that consolidated at different times and over a ridged environment. Geostatistics (namely the variogram) was used to examine the statistical characteristics the snow distribution over various types of sea ice (smooth FYI, rough FYI) using point measurements of snow depth. This work examined if and how the consolidation time of sea ice impacts the snow distribution observed on the sea ice. In theory, the snow depth will be different for the different locations (location with an earlier consolidation time would have had more time to collect snow and thus has a greater snow depth, assuming all other things constant). However the question as to what impact earlier/later consolidation will have on the spatial distribution of snow depth has not been addressed in the literature. The affect ridges have on the snow distribution is also an aspect of the icescape that has not been examined in terms of snow distribution and has implications on marine mammal habitat (i.e. polar bear). Variogram sampling (Carrie Breneman, Christina Blouw) Snow distribution was sampled using the non-repetitive, destructive “variogram” method. This method involves sampling the snow depth in eight directions from a central location (Figure 10).

Figure 10. Schematic of the sampling methodology used for measuring snow distribution. Snow depth is sampled in the eight directions from the center point using the Snow-Hydro Magmaprobe® digital snow probe. The ice types that were sampled include smooth first-year sea ice as well as rough first-year sea ice. For rough first-year ice sample sites, topography data from surveying methods were also recorded. Variograms were completed once a week.

Time Series of Snow Macrostructure (C.J. Mundy, Chris Konig) In order to examine the temporal change of snow distribution over a smooth surface, a set of wires were stretched between poles using a similar structure as outlined in Figure 10, but with lines of 20m length extending from a central location. This site was called Appun (Figure 1). The height from the ice surface to the each wire was measured at installation. Snow depth was measured using a Wenglor® Laser Reflex Sensor with reflection time measurement which measured distance from the sensor to the snow surface providing a non-destructive measurement of snow depth through subtraction. The sensor was sent down each 20m wire using a pulley system to measure the distance from the wire to the snow surface at 0.5m intervals (Figure 11). Installation of the lines was completed on March 5, 2004. Sampling of the lines occurred only if drifting took place the previous day or night.

Figure 11. Pictures of the snow distribution time series measurements (Photos: Chris Konig).

Problems

As this was a proto-type experimental set-up, some foreseen and unforeseen problems were encountered. The first, a foreseeable problem, was the effect of wind on the sensor’s vertical orientation. Wind would induce a tilt on the sensor, which was subtracted by measuring the tilt of the sensor for a given line and day. The second, also a foreseeable problem, was the sag of the line. This was measured at during the initial set-up where no snowdrifts had yet existed. A third unforeseen problem was the breaking of wires during cold and windy events. The solution was to tighten all the wires right before measuring the site, and then loosen all the wires before leaving the site. Due to hardware supply limitations, only 6 of 8 wires were able to be re-installed after a major storm. Therefore, snow distribution was measured in every direction except for the North-South direction.

Natural Ridge Environments: Ridges located within Franklin Bay were used to examine the distribution of snow within this natural setting. Ridges of varying height and width were randomly selected within the study area. Once a ridge was located, snow depth was first measured (using a digital snow probe) along two transect lines set up orthogonal to the direction of the ridge, one on either side of the ridge. Topography measurement were also taken along the same transect lines. This information will eventually be used in conjunction with the snow depth and measurements along artificial ridges to examine the effects of this feature on snow distribution. Ridges were sampled three times per week.

Figure 12. Sample ridge transect line and sampling expedition.

Snow Fences: Four artificial ridges (Snow fences) were assembled within a 2-km2 area on the sea ice near the icebreaker. These artificial ridges were assembled early in the winter and were allowed to catch snow throughout the winter, with the purpose of modeling the snow distribution along a natural ridge environment. Running orthogonal to the direction of the ridges a wire was used as a reference for the estimation of snow depth (Ablation lines). Along with the wires, small marker flags directly under the line were also used for identification of snow height directly under the ablation line. Digital video clips were taken of the accumulating snow drifts on either side of the individual fences to allow for further

digitizing and calculation of snow drift height. These snow fence video clips were taken approximately every second day, weather permitting. Visibility must be good in order to obtain quality data.

Figure 13. Fences F6, F7, F2 and F3 were used for the ablation line videos. There respective heights are identified in the field plan above.

Polar Bear Habitat Grids: A grid 10 km by 10 km was identified north of the ship and was further divided into one hundred 1 km by 1 km plots. Numbered plots were randomly chosen and samples in a systematic fashion. The plots were identified through 4 corner GPS points. A transect was completed by 2 snowmobiles covering the entire perimeter as well as an east to west line every 100 m. Transect lines were used to survey for polar bear tracks. If a track was located, habitat as well as track properties were recorded. This data will be used to understand the relationship between sea ice and polar bear abundance, potential habitat and residence time. The track position was recorded on a Trimble GeoXT GPS unit on one of the snowmobiles. These grids were sampled approximately 3 times a week.

Figure 14. Satellite imagery of the 10 km by 10 km grid sample area

Figure 15. Habitat grid coordinates for individual plots

Figure 16: Actual GPS copy of grid transect track line for Feb. 16/04

Figures 17. Two polar bear track photos

Ice geophysics (C.J. Mundy) Physical properties of sea ice were collected on a weekly base throughout leg 5 in conjunction with sampling by other CASES participants including CO2, contaminants, bacterial and primary production and biomass measurements. On each sampling day, snow depth, ice thickness, freeboard height (distance from water level to ice surface) and a temperature profile (10 cm interval) were measured in the field. Additional ice cores were brought back to the ship for profile measurements (10cm interval) of salinity, density and microstructure. Ice thin sections were prepared using a hand plane, following a method developed on Leg 2. Pictures of brine inclusion size using a dissecting microscope were taken. Further, pictures of crystal structure were taken using a light table and cross-polarized sheets with a macro setting on the camera. The cores were characterized as follows:

- Thickness (using a measuring tape)

- Temperature (using a drill and temperature probe Hart Scientific Model 1522)

- Salinity (using a salinometer Hoskin Scientific Cond 330i)

- Microstructure (using a Canon Powershot G2 4.2 megapixels and cross-polarized sheets)

- Density (using a digital caliper and a scale)

Satellite Validation (Steve Howell, Randall Scharien)

Rationale

Microwave remote sensing is a popular tool for monitoring changes in sea ice due to the ability of microwaves to penetrate cloud cover and image irrespective of sunlight. The implementation of microwave remote sensing imagery into useful information in sciences and operations requires the calibration of scatterometric (active) and radiometric (passive) microwave signatures of sea ice at the surface. It has been demonstrated that, under cold conditions, Arctic sea ice types have stable microwave signatures that can be linked to their type. During warming seasons (i.e. typically above ~268K) diurnal temperature fluctuations and changes in the overlying snow pack (e.g. availability of free water, snow metamorphism, etc.) cause significant fluctuations in microwave signatures. These fluctuations create ambiguities in the interpretation of imagery and errors in algorithm-based image products. Linking changes in microwave signatures to changes on the surface allows for the geophysical inversion of surface processes (e.g. appearance of liquid water in the snow pack). The advent of multipolarimetric microwave data concurrent with the launch of the European Space Agency’s ENVISat-ASAR platform, and the pending launch of Canada’s RADARSAT-2, yields a new potential for discriminating sea ice physical conditions in all seasons. The interpretation of new imagery from these platforms requires accurate ground validation.

Objectives The principle objective of Leg 5 was to mobilize the scatterometer system for the purpose of site validation of ENVISat-ASAR imagery. The scatterometer system is a C-band (5.3 GHz), dual-polarization, solid-state radar that uses a two-axis positioner to measure microwave scattering at a range of incidence and azimuth angles. It is a sensitive system involving many components that require testing and calibration prior to mobilization. The aim of Leg 5 participants was to establish a mobile scatterometer protocol that minimizes errors and ensures data reliability for future leg participants. This aim was set to coincide with the beginning of the spring season and Leg 6, at which time thermodynamic changes in the snowpack will increase the need for time-series and mobile site validations. A second objective of Leg 5 participants was to establish sampling sites by which the scatterometer can be used to measure temporal variations in microwave signatures. These microwave data will also be coupled to snow and ice physical properties for the validation-development of SWE algorithms. A third objective was to operate the surface-based radiometer (SBR), a passive microwave system that was mounted on the ship during a pervious leg. Data collection procedures for the SBR had been previously established. The goal of this project was to maintain the collection of natural microwave emissions from snow-covered sea ice over an area off the ship marked-off to prevent traffic.

Scatterometer Activity Report The scatterometer system is a newly built system, and as such is subject to “bugs” in its reliable operation using its support software. The duration of Leg 5 was centred on troubleshooting the scatterometer system and testing its reliability under the stresses involved in making it mobile under severe temperatures and winds. The scatterometer and its support computer (CPU) have been built with internal temperature controls and housings geared for Arctic conditions. However, the support structure (wireless network, power generator, UPS, etc.) have not. A considerable amount of time was dedicated to troubleshooting problems associated with the scatterometer support structure. We were able to fix a problem from Leg 4 whereby the two-axis positioner that mounts the scatterometer was not responding. This required the reconfiguration of the tracker’s internal software. The tracker does still lose its configuration program occasionally, quite possibly because the tracker’s internal battery does not withstand cold temperatures for long enough to support the internal tracker memory. A procedure has been established for the timely reconfiguration of the tracker should it shut down.

The power support system, involving a portable generator, a UPS system, and a voltage regulator was not able to support the full scatterometer in a mobile set-up. It was discovered that this was not a problem of power consumption but rather a UPS sensitivity issue combined with too much power drain directly from the voltage regulator. The wiring configuration was modified to allow minimal drain on the UPS and maximum directly from the generator while still protecting the sensitive components of the scatterometer system (i.e. the radar and CPU). We were also able to troubleshoot various errors associated with wireless communication with the scatterometer CPU from a laptop station established in the Takatuk parcol. We were also able to remedy the inability of the scatterometer software to reliably recognize and communicate changes in angle (incidence, azimuth) with the two-axis positioner.

Figure 18. Mobile scatterometer system (radar, two-axis positioner, CPU, wireless network, UPS, and generator – from left) mounted on a komatik.

Three sampling sites were established, as follows: “Takatuk” Time-Series Site Two sites were set up near the Takatuk parcol for the purpose of measuring time-series changes in microwave backscatter over relatively smooth, first-year sea ice. Time-series 1 (TS1) is a small (~ 5 m by 10 m) section of relatively shallow snow (approx. 5 cm deep) by which microwave scattering is measured over a range of incidence angles (15 – 65 degrees) and azimuth angles (50 degree range). Time-series 2 (TS2) is the same size as TS1, sampled the same way, but for a relatively thick (> 8 cm) snow cover. Sampling is done at these sites coincident to the collection of snow physical property data (i.e. snow-pit sampling) and micro-climatological data (i.e. met station data). We were able to collect a few scans with the mobile scatterometer system at these sites. The data is still in preliminary format and will be analyzed initially by Leg 6 participants. “G-Site” Profile Site The G-Site was established as a 350 m by 500 m area of undisturbed smooth, first-year sea ice for the purpose of transect sampling of microwave scattering at angles similar to the ENVIsat satellite. This site is NW of the Takatuk time-series sites. ENVISAT-ASAR Validation The recent availability of multi-polarization satellite data from ENVISAT-ASAR and SeaWinds/QuikSCAT combined with the eventual launch of RADARSAT-2 and TerraSAR allow for more robust estimates of remotely sensed sea ice geophysical variables. During CASES 2003-04 ENVISAT-ASAR polarmetric signatures will be utilized to describe sea ice thermodynamic properties

and quantify snow depth over FYI. In order to accomplish this, in situ snow and ice physical property must be collected immediately following ENVISAT-ASAR satellite overpass. During CASES Leg 5, two ENVISAT-ASAR validations were performed. The ENVISAT-ASAR validations took place on March 11 and 27 corresponding to descending HH/VV and descending VV/VH overpasses, respectively. For the March 11th overpass 8 random points were selected within 1km2 region of smooth FYI located NW of the Amundsen (Figure 1). For the March 27th overpass 6 random points spanning 250m2 were selected within the initial March 11th overpass 1km2 region (Figure 19). At each site, full profile snow pit data were collected, consisting of snow depth, ice thickness, and temperature and capacitance profiles. At every 2 m interval a snow sample was collected to determine bulk density, salinity and snow grain pictures of each layer in the profile. A sample of the ice surface was also collected to determine salinity. Problems Only ENVISAT-ASAR descending passes were possible because of the lack of sunlight during ascending passes.

Figure 19. Location of the ENVISAT-ASAR validation sites with respect to the Amundsen.

Surface-based Radiometer (SBR) Activity Report The SBR has been very stable and efficient during the whole duration of LEG5. However, some very cold day were skipped in order to protect the SBR. Some problems occurred with the calibration of 19GHz. The SBR was not able to calibrate that frequency efficiently. We thus applied old calibration files when the 19GHz channel was functioning. We have since decided to use recent calibrations, even with weak 19GHz results (Ken Asmus, pers. comm.). The system operated without a problem through the full duration of Leg 5.

Ice Deformation and Satellite Validation (Carrie Breneman, Christina Blouw)

Introduction Much of the variability observed in sea ice thickness is associated with sea ice dynamics through converging and diverging flow. Areas of converging produce pile-ups of ice forming pressure ridges, finger rafting and rubble fields whereas diverging ice produces fractures or leads. Sea ice deformation is primarily controlled by surface wind stress, ocean currents and bathymetry but there is a limited understanding of the scale and magnitude of physical processes responsible for ice deformation.

Remote sensing imagery (ENVISAT ASAR and Radarsat-1) will provide a means to identify and monitor ice deformation throughout the winter season. The primary objective of this study is to monitor landscape level ice deformation to improve the understanding of the relationship between spatial and temporal patterns of ice deformation development and the physical processes that are responsible for them.

Our field objectives for the CASES 2004 Leg 5 cruise were to:

1.) Ground truth and validate remote sensing imagery for a variety of ice types (smooth first year sea ice to multi-year);

2.) Measure ice topography in rough ice zones to validate and differentiate different deformation areas in the satellite imagery.

Sampling: Remote Sensing Imagery Real-time Envisat imagery was acquired on January 14, 17 and 21, 2004 and was available within 5 days onboard the ship (provided in-kind from the Canadian Ice Service) (e.g., Figure 20). Envisat data was available in several polarizations (VV, HV and HH) at 12.5m resolution. Radarsat-1 data was acquired on January 1, 2004 at 100m resolution (VV polarization). The sites were identified from the imagery and with the high spatial resolution (12.5m) acquired on January 14, 2004 (Figure 20) and a variety of ice types were identified. The smooth first-year ice corresponds with a dark (black) return and lighter returns correspond to areas of deformation (in the VV-imagery). Large homogeneous areas of high backscatter that appear light are rubble or finger rafting and tend to be areas of low height but high density. Areas with high standard deviations in backscatter tend to have the highest individual ridge features interspersed with smooth or rubble ice.

Figure 20: Envisat Asar image – acquired January 14, 2004 in VV polarization. Figure © ESA.

Sampling: Rough and smooth ice validation

For areas of smooth first year ice, the validation consists of several photograph, GPS location and an estimation on the extent of the smooth area. For rough ice validation, the ice topography/roughness was measured using surveying equipment to determine the frequency and distribution of ice ridge/deformation features. Using the level and stadia, the ice surface topography is surveyed at a 1m interval for 25 point locations in 4-directions. The orientation, GPS location of the deformed area along with a photograph, sketch and a description of the area ice area was acquired. In total, 20 sites additional to the 45 sites done during leg 4 were located on the imagery and validated in the field. Considering the amount of daylight, low temperatures and difficult travel during the leg, there is a large spatial distribution of sites. All directions were traveled from the ship; the closest site was 500m and the furthest 30 km. 3 Light, Nutrients primary and export production in ice-free waters

3.1 Phytoplankton in the water column, Nutrients,

and Japanese collaboration (Sub-project leader : Serge Demers, Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Québec, Canada) Cruise participants: Karine Lacoste and Shinya Yamamoto

On board collaborators: Marek Zajaczkowski, Wojtek Moskal, Bernard Leblanc, Tara Businski, Carlos Pedros-Alio, and Sébastien Roy

Objectives

• to assess the biomass and the production of pico-, nano- and microphytoplanktonic cells at the winter sites of the CASES project

• to determine species composition and pigment composition of phytoplankton in the upper part of the water column

• to define the bio-optic characteristics of the assemblages of pico- and nanophytoplanktonic cells by flow cytometry

• to determine nutrient levels in the water column

• to determine the photosynthetic and optical properties of phytoplankton in surface water and sediment trap as well as of ice algae in ice cores (specific to japanese collaboration)

• to determine spatial variability of surface waters by doing a “Synoptic Water Sampling (SWS)” of all ice sampling sites

Methods

Study site

Water samples were collected primarily at the CASES over-wintering site in Franklin Bay. Sampling of the water column was completed by taking surface samples from the nearby Titicaca site. The waters of Angaguk and Takatuk sites were also sampled and ice cores and sediment trap content were taken from the Takatuk site.

Water column sampling and analyses Water samples were collected using the rosette, go-flow bottle, and/or water pump depending on site and depth sampled. Water from 8 depths (10, 15, 25, 50, 75, 100, 150, near bottom) was collected every 6 days from the moonpool for the determination of chlorophyll a (chl a), phaeopigments, pigment composition, particulate organic carbon and nitrogen (POC and PON, respectively), BioSi, and species composition. Samples were also taken for further analysis on flow cytometry to determine the population composition of the small size class of phytoplankton and cells flurorescence. The same variables were studied at the Angaguk and Titicaca sites however only in surface waters i.e. 3 and 10m. Additional surface water was collected at the Titicaca site to study the specific absorption coefficient (a*). Water from the same depths as the sediment traps was collected every 8 days from the Takatuk site in collaboration with the sediment trap team to assess chlorophyll a (chl a), phaeopigments, pigment composition, particulate organic carbon and nitrogen (POC and PON, respectively), BioSi, species composition, and to perform flow cytometry analyses. Nutrient samples were collected at all sites sampled with additional depths for the rosette sampling to allow a better profile of nutrient levels in the water column. The concentrations of nitrate, orthophosphate and orthosilicic acid will be further determined on board by Neil Price’s team using an ALPKEM autoanalyzer with routine colorimetric methods (Grasshof 1999). Experiments were conducted to assess the primary production at the over-wintering site using water collected from the moonpool. Primary production at 10 and 25m was estimated using the 14C uptake method.

The response of photosynthetic carbon assimilation to light (PI curves) in the surface waters of the over-wintering site (10 m) and Titicaca site (3 and 10 m) was obtained by 14C uptake using a small-volume and a short-incubation time method.

Samples for chl a, phaeopigment, and nutrients were taken from the bottom-tripping Niskin in collaboration with Tara Businski (Don Deibel’s group).

Sediment trap sampling and analyses Sediment trap content was collected every 8 days from the sediment trap deployed 1m under the ice at the Takatuk site. Samples were analysed for a* and PI curves experiment were done. Other analysis were done with the collaboration of the sediment trap team. See “Under-ice sediment traps and Ice algae” report for further details.

Ice core sampling and analyses Ice cores were collected weekly at the Takatuk site using an ice corer and taking the 10cm of the base of the core i.e. water-ice interface. Samples were analysed for chl a, a*, POC/PON, pigment composition (HPLC technique), nutrients, and taxonomy. PI curves experiment were also done. Synoptic Water Sampling (SWS) An additional sampling was done on the 12th of March in collaboration with the microbial team. This specific sampling was designed to investigate the spatial variability of the phytoplanktonic and microbial community in the surface waters of the ice sites sampled during leg 5. Water was collected at 3 m deep in 7 holes on the ice using a go-flow bottle (see “Microbe” cruise report section for more details on sampling). Our group specifically took samples for Chl a, POC/PON, BioSi, taxonomy, flow cytometry, and nutrients analyses.

Preliminary results Total Chl a for three sites of leg 5

Comments: Due to extreme cold conditions, we experienced difficulties in keeping our samples non-frozen when sampling at the ice sites. Fortunately, this problem was solved within a couple of weeks. Initially we were using our thermos containers and putting them in coolers filled with warm water. It turns out that this type of thermos not only are bad at ensuring that samples stay unfrozen until processing in the lab, it also takes much longer for them to unfreeze in the lab after returning from the sampling site. We found that the best method of sampling was by using a 20L Carboy Nalgene bottle or those collapsable plastic containers. These containers however do not preclude the use of warm water either in the coolers in which they are stored or in the containers themselves. Acknowledgments We would like to give special thanks to our wonderful chief scientist, Jody Deming, for having been such a great leader and colleague on board. A big thank you as well to the coastguard crew for helping us in our sampling activities and in ensuring that our lives on board was so pleasant. Sampling would not have been possible without the help of Mykolay, Sébastien, Carlos, Tara, Louis, Catherine, Alexandre, Gérald, Tara, Wojtek, Marek, Bernard; thanks guys! And lastly, we wish to give our sincere thank you to Noel Green, for being with us in this great scientific adventure, making sure that we were safe and being such a great on and off the ice companion.

Sampling during leg 5. Nut: nutrients; Chl a: Biomass of phytoplankton (Total and >5µm); CHN: POC, PON; BioSi; Cells: taxonomy; Cytometry: Flow cytometry; a*: specific absorption coefficient; HPLC: pigment composition; PP: primary production; PI: photosynthesis-irradiance relationships.

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04-janv 14-janv 24-janv 03-févr 13-févr 23-févr 04-mars 14-mars 24-mars 03-avr

Chl

a (µ

g/m

³)

Titicaca siteTakatuk siteAngaguk site

Synoptic Water Sampling at 3m

0,00 0,03 0,05 0,08 0,10

Takatuk #1

Takatuk #2

Dukuduku #1

Dukuduku #2

Titicaca

Angaguk #1

Angaguk #2

Stat

ion

Chl a Total (µg/m³)

Station Date Nut Chl a CHN BioSi Cells Cytometry

a* HPLC

PP PI

Winter 20/02/04 X X X X X X X X X Titicaca 21/02/04 X X X X X X X X X X Tripping Ni ki

22/02/04 X X Ice core 22/02/04 X X X X X X X Winter 26/02/04 X X X X X X X X X Titicaca 27/02/04 X X X X X X X X X X Tripping Ni ki

28/02/04 X X Ice core 29/02/04 X X X X X X X Winter 03/03/04 X X X X X X X X X Takatuk 03/03/04 X X X X X X Titicaca 04/03/04 X X X X X X X X X X Tripping Ni ki

05/03/04 X X Angaguk 05/03/04 X X X X X X Sampling during leg 5 (continued). Station Date Nut Chl a CHN BioSi Cells Cytometr

y a* HPL

C PP PI

Angaguk 26/03/04 X X X X X X Winter 27/03/04 X X X X X X X X X Takatuk (water

27/03/04 X X X X X X X X

Ice core 28/03/04 X X X X X X X Titicaca 28/03/04 X X X X X X X X X X Tripping Ni ki

29/03/04 X X Ice core 07/03/04 X X X X X X X Winter 09/03/04 X X X X X X X X X Titicaca 10/03/04 X X X X X X X X X X Tripping Ni ki

11/03/04 X X Takatuk (water

11/03/04 X X X X X X X X

SWS 12/03/04 X X X X X X Ice core 14/03/04 X X X X X X X Winter 15/03/04 X X X X X X X X X Titicaca 16/03/04 X X X X X X X X X X Tripping Niskin

17/03/04 X X

Angaguk 19/03/04 X X X X X X Takatuk (water

19/03/04 X X X X X X X X

Winter 21/03/04 X X X X X X X X X Ice core 21/03/04 X X X X X X X Titicaca 22/03/04 X X X X X X X X X X Tripping Ni ki

23/03/04 X X 3.2 Polish CASES Team Report Cruise participants: Marek Zajaczkowski and Wojtek Moskal. Institute of Oceanology, Polish Academy of Sciences 55 Powstancow Warszawy Str. 80-712 SOPOT, POLAND The Polish Team on Leg 5 was included to 2.3 CASES subprogram. Principal investigators: Christine Michel, Michel Gosselin, Michel Poulin. The intent of our team was to collect data on sedimentation rate in deeper part of water column (180 m) and to collect the data on concentration of suspended matter (organic and inorganic) in whole water column on the layers where sediment traps were deployed. Concentration in water:

• Suspended solids (SS organic and inorganic) – sample filtered on Whatman GFF • Chlorophyll - sample filtered on Whatman GFF • POC/PON - sample filtered on Whatman GFF • Phytoplankton cells ( also fecal pellets) 3000 ml of water filtered on net 20 μm

Rate of sedimentation (sediment traps sample)

• Susupended solids (SS organic and inorganic) – sample filtered on Whatman GFF • Chlorophyll - sample filtered on Whatman GFF (frozen) • POC/PON - sample filtered on Whatman GFF (dryed, frozen) • Phytoplankton cells, also fecal pellets. 250 ml.

Samples Collected

Series Date Place Water / Trap Chl POC SS (ml) Phyto

0 25/02 Takatuk 1 m (water - ice hole)

2 x 500 ml

1000 ml (blue) 2000 2000 ml

0 25/02 Takatuk 15 m (water - ice hole)

2 x 500 ml

1000 ml (yellow) 1000 3000 ml

0 25/02 Amundsen25 m (water - moonpool)

2 x 500 ml

1000 ml (red) 1000 3000 ml

0 25/02 Amundsen180 m (water - moonpool)

2 x 500 ml

1000 ml (green) 1000 3000 ml

1 03/03 Takatuk 1 m (trap - ice hole) B B 500

250 ml (B)


250 ml (B)


250 ml (B)


250 ml (B)

1 03/03 Takatuk 1 m (water - ice hole) K K 1000 3000 ml



1 03/03 Amundsen180 m (water - moonpool) K K 1000 x

1 04/03 Amundsen180 m (water - moonpool) x x x 6000 ml


250 ml (B)


250 ml (B)


250 ml (B)


250 ml (B)




2 11/03 Amundsen180 m (water - moonpool) K K 1000 2000 ml

3 18/03 Takatuk 232m (trap-ice hole/24h) x x 1000 x


250 ml (B)


250 ml (B)


250 ml (B)


250 ml (B)

3 19/03 Takatuk 1 m (water - ice hole) K K 1000 x



3 19/03 Amundsen180 m (water - moonpool) K K 1000 x


250 ml (B)


250 ml (B)


250 ml (B)


250 ml (B)

4 27/03 Takatuk 1 m (water - ice hole) K K

1000 (GFF)

3000 ml + 250 ml


1000 (GFF)

3000 ml + 250 ml


1000 (GFF)

3000 ml + 250 ml

4 27/03 Amundsen180 m (water - moonpool) K K

1000 (GFF)

3000 ml + 250 ml

B – Bernard Leblanc K – Karine Lacoste The central hypothesis in CASES project relates to the processing of organic matter in the Mackenzie delta versus offshore waters and its relationships with sea ice conditions. Franklin Bay is located on the side of Mackenzie shelf, however the influence of brackish water is noticeable on its surface. Additionaly during the reconnaissance on station Angaguk the income of fresh water from Horton River was affirmed. The physical oceanography subprogram was therefore formulated to measure dynamics of Franklin Bay water, in particular:

• Advection on the layers where sediment traps were deployed (Takatuk). • Salinity and temperature on the stations Takatuk, Angaguk, North and South from Takatuk • Fresh water input from Horton River • Turbidity currents in nephyloid zone.

During strong Western and North-Western wind the current driven 178O(average velocity 10.2 cm s-1) was noted on the depth of 10-27m. At the some time in near bottom area a current driven North reached velocity 9.4 cm s-1 (see Fig.1)

-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 1011Current [cm s-1]

150140130120110100

9080706050403020100

Dep

th [m

]

North South

Fig.1 Currents velocity and direction on Station Takatuk 23.03.2004. We suggest that during such wind polynia could be open and water from Mackenzie Shelf could be driven in to Franklin Bay. The data presented on Fig.2 confirms the influence of Mackenzie Shelf water on Franklin Bay. During whole Leg 5 we could observe less saline water layer (30.5 PSU) on the depth 0-16m in February and 0-25m in second half of March.

0 2 4 6 8 10 12 14 16 18Distance [km]

-150

-130

-110

-90

-70

-50

-30

-10

Dep

th [m

]

North Takatuk South

Fig.2 Salinity cross section in Franklin Bay 20.03.2004. The input of fresh water from Horton River during the winter is insignificant. We estimated daily fresh water delivery as 25,000 m3, however the influence of Horton River was noted on Station Angaguk located 4.3 km from river mouth (see Fig.3). The layer of two meters of brackish water (25.4PSU) was noted on the surface as well as increase of suspended solids concentration to12.2 mg dm-3. During North-Western wind the influence of Horton River was imperceptible on Station Angaguk.

The current and FTU (formazine turbidity units) measurements in nephyloid zone (Fig.4) show the transport of suspended matter over the bottom. Turbidity currents can play an important role in transport of sediment (also organic matter) to deeper part of Beaufort Sea shelf.

24 26 28 30 32 34Salinity [PSU]

160150140130120110100

9080706050403020100

Dep

th [m

]

-2.5 -2 -1.5 -1Temperature [oC]

15 20 25 30Density

Angaguk, 27.02.2004

Fig.3 Salinity, temperature and density profile, Station Angaguk 27.02.2004.

0 100 200 300 400 500 600 700Time [minute]

0.51

1.52

2.53

3.5

Curr

ent [

cm s-1

]

0

10

20

30

40

SS c

once

ntra

tion

[mg

dm-3

]

Moon Pool, 30cm over the bottom21-22.03.2004

10o 14o 10o 14o DIRECTION

Fig.4 Turbidity currents in nephyloid zone under the Amundsen Ship.

4 Microbial Communities and heterotrophy

4.1 Microbial ecology

CASES 2003-2004 Leg 4 (8/1-18/2/2004) Warwick F. Vincent, Département de biologie, Université Laval, Québec,Canada Curtis Suttle, University of British Columbia, Canada Carlos Pedrós-Alió, Institut de Ciènces del Mar, Barcelona, Spain

Cruise participants: Sébastien Roy and Carlos Pedrós-Alió The central hypothesis in CASES concerns the processing of organic matter in the Mackenzie delta versus offshore waters and its relationships with sea ice conditions. Microorganisms are likely to contribute substantially to the biological carbon stocks across this region, and to play a leading role in the biogeochemical fluxes of organic matter. The microbial ecology subprogram was therefore formulated to measure microbial community structure and production dynamics throughout the CASES study region, including comparative measurements in the inshore delta and Mackenzie River source waters. Key objective of the microbial subprogram on Leg 5 was to study the abundance, diversity and production of the microbial community during the period of transition from the arctic winter to the springtime. A) Core measurements I Sampling During this leg the research vessel Amundsen stayed in the Franklin Bay frozen into the ice. The location was named Winter 1 during leg 3. Water column samples were taken from 5 regular depths (bottom, 150m, 100m, 50m and temperature inversion) from the moon-pool using a rosette. The surface samples (10m, 3m from the ice surface) were taken from Titicaca site, 500 m from the ship, and twice during the leg at Angaguk site (18 km from the ship) with a 5L Go-Flo bottle or/and a pump. Sampling cycle for most of the samples was 6 days.

I. Abundance of microorganisms At each of the samplings (moon-pool and Titicaca) the following samples were taken from all depths mentioned above (except if specified otherwise):

Picocyanobacteria (slides); Component 5 in Figure 1.

Heterotrophic prokaryotes (DAPI-slides); Component 1 in Figure 1.

Small flagellates (DAPI-slides); Components 2 and 4 in Figure 1.

Size-fractionated Chorophyll a (total and < 3 μm); Components 4, 5, and 7 in Figure 1.

Picoplankton abundance (flow-cytometry); Components1, 2, 5 and 4 in Figure 1.

Ciliate abundance (Lugol’s preserved samples) only from two profiles. Component 3 in Figure 1.

Protists were collected from surface and at temperature inversion (FNU preserved for fluorescence-Nomarski- Utermöhl microscopy). Components 2, 3, 4 and 7 in Figure 1.

Viruses (flow cytometry) on six of the seven sampling dates. Component 6 in Fig 1.

Dissolved organic material

0.02

0.2

2

20

200

2000

20000

VirusFemto

Pico

Nano

Micro

µm

1

2

3

5

4

6

7

8

Fig. 1. Simplified scheme of the planktonic food web indicating the organisms and fluxes analyzed in the present leg (in purple).

II Identity of microorganisms

a) FISH (components 1 and 2 in Figure 1)

Samples were collected from seven depths in every profile, fixed with formalin, and filtered on 0.2 (for bacteria) or 0.8 (for flagellates) µm filters. The filters were frozen at –20 degrees and will be analyzed in the lab with fluorescent probes for different bacterial and eukaryal groups.

b) DNA (components 1, 2, 4, and 5 in Figure 1)

Samples were collected at three depths (3 m, temperature inversion and bottom) from every profile. Between 10 and 14 liters were prefiltered through 50 µm net, 3 µm prefilter and 0.2 µm Sterivex filter. The 3 µm and 0.2 µm filters were then preserved in lysis buffer and frozen at –80 degrees. The filters will be used to extract the nucleic acids and explore the diversity of the microbial assemblage with a variety of techniques (such as DGGE, clonig and sequencing).

c) Other. Lugol’s and epifluorescence samples will be used to partially identify ciliates (component 3) and flagellates respectively (components 2 and 4).

III. Activities of microorganisms a) Prokaryotic heterotrophic production (component 1)

Heterotrophic production measurements were carried out at every sampling. Some supplementary experiments were also conducted (see below). Replicates from each depth were incubated for 4 h with 3H-thymidine to measure bacterial DNA synthesis and 3H-leucine to measure bacterial protein synthesis, according to JGOFS protocols refined by Josep M. Gasol (ICM, Barcelona, Spain). The incubations were made in micro-tubes (2 mL) and were terminated by addition of trichloroacetic acid (50%), and then centrifuged for 10 minutes at 12 000 rpm. The supernatant was removed by suction and the micro-tubes were rinsed with ice-cold TCA (5%), before a second centrifugation (10 minutes at 12 000 rpm). The supernatant was removed a second time and scintillation cocktail was added to microtubes. After 24-48h of rest in the dark the samples were counted with a TriCarb 2900 (Packard).

Conversion factor experiments.

Three experiments were carried out to determine the conversion factors between leucine and thymidine incorporation and prokaryotic heterotrophic production. The first experiment was carried out with 3 m water collected on February 27 (CF-4). The other two experiments were carried out with water collected on March 15 at 35 m (CF-5) and March 16 at 3 m (CF-6). Approximately 400 ml of 0.8 µm-filtered water were diluted with 1600 ml of 0.2 µm filtered water. Two replicates per experiment were done. Samples for cell abundance and leucine and thymidine uptake were collected daily for 15 days.

Saturation and time course experiments

Extra water sample were taken on day 25/03/04 to conduct a time series experiment followed by a saturation curve experiment. For the time series experiment, subsamples of surface water (Titicaca site) were incubated with 10nM of 3H-leucine and 3H-thymidine for 1h, 2h, 3h, 3h30, 4h, 4h30…7h30 (three replicates for each time point). For saturation curve experiment, we incubated water with 5, 10, 15, 20, 30, 40, 60 and 80nM of 3H-leucine and 3H-thymidine.

b) Grazing experiments (Flux between components 1 and 2) Experiments to determine bacterivory were carried out twice during this leg. The FLB disappearance method was used and samples were incubated for 48 hours. Profiles of ciliate abundance were taken on the same dates.

c) BIOLOG (Component 1) At each sampling date, three depths were selected to inoculate BIOLOG plates (3 m, temperature inversion and bottom). The plates were incubated at 4 degrees for a minimum of 15 days (or until colour developed in some of the wells).

d) MARFISH (Component 1)

On two sampling dates, surface samples were used to analyse the uptake of glucose, aminoacids and ATP by heterotrophic bacteria. Samples were incubated with these substrates and filters prepared for MicroAutoRadiography combined with Fluorescent In Situ Hybridisation. (MARFISH).

B) Additional measurements during leg 5 a) Dissolved organic matter (Component 8). From every depth at each sampling, FCDOM (for synchronous fluorescence characterization and sourcing of the dissolved organic matter), CDOM spectral absorption, and DOC samples were collected.

Three times during this leg, further surface samples (5L filtered through 0.22 µm membranes) were obtained for photochemical action spectra of CDOM photodegradation and hydrogen peroxide

formation. In parallel, 35 L of acidified water (pH ~2) were treated for lignin extraction on sorbent C18. These samples were collected at Titicaca station (twice) and at Angaguk site (once) that is located 5 km from the mouth of Horton River. Lignin work will be conducted by Dr. Chris Osburn, at the Marine Biogeochemistry Section of US Naval Research Laboratory, Washington, DC.

b) Pigments from autotrophs (Components 4, 5 and 7). Samples for HPLC pigments were collected at the surface and temperature inversion (total and <3µm).

c) Microbial plankton composition (Components 1-7).

Samples for the determination of macromolecular ratios of particulate material, (POC/PON, POP and DNA/RNA/protein), that are used to obtain an indication of the physiological and nutritional state of the microplankton communities, were also taken. Between 7 and 10 liters were filtered for each parameter through a precombusted GF/F filter and frozen in liquid nitrogen. Analysis will be conducted at ICM (Barcelona).

Samples for particulate and dissolved DMSP and DMSO that are critical for understanding sulfur cycling with its direct impact on the nature of carbon cycling in the ocean, were taken from surface water, analysis will be conducted at ICM.

Size-fractionated (total and less than 3 µm) seston samples for dry weight measurements were taken from 3 depths (surface, bottom and 20m or temperature inversion when present) at each sampling. Twice during this leg, seston samples were obtained on precombusted GF/F filter for stable isotope analysis (�13C and �15N) from the water surface as a further guide to the source of POM.

Preliminary results. Most measurement will be carried out in the labs in Quebec and Barcelona. But the chlorophyll values determined on board show a very clear trend of increasing biomass in the upper water layers since middle February (Figure 2). This increase is due to small microorganisms, probably between 3 and 5 micrometers in size, judging from the preliminary size fractionation data from Demer’s group and our own data. If the rate of increase were maintained, levels of chlorophyll similar to those at freeze-in would be reached in the second half of April (leg 6). But, of course, there could be a slow down if there were shading by increases in biomass of ice algae. At any rate, these results clearly prove that the ecosystem has “turned on” at a much earlier date that commonly thought. This is justification enough for a winter cruise such as CASES 2003/04.

0.1

1

10

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100

-100 -50 0 50 100 150

CASES 2003/04

Chla 10mChla 20m

Chla 220m

Chl

a 10

m o

r 20m

(mg/

m2) C

hla 220m (m

g/m2)

Julian Day

Freeze in

Fig. 2. Integrated chlorophyll a values for the surface layer (2 to 10 m and 2 to 20 m) and for the whole water column (2 to 220 m) from freeze-in to end of March. Note different scale for whole water column integration.

C) Synoptic Water Sampling (SWS) One of the most interesting points of CASES 2003/04 is the repeated sampling throughout the year of a given spot in the Arctic Ocean. During open water periods sampling at this station is complemented by other sampling transects. These additional samples indicate whether conditions at the over wintering station are peculiar to the site or common to a larger area.

We decided it would be very useful to have a similar sampling during the ice period. Therefore we carried out a synoptic water sampling. Due to logistical problems, the distance from the ship had to be necessarily limited. But at least there would be some information about the variability in space of the microbial community in surface waters.

As a working hypothesis, we expected Dukuduku and Titicaca to be essentially replicates, as the two holes at Takatuk and the two at Angaguk. We expected DukuDuku and Takatuk to be similar, but how similar is what we wanted to find out. Finally, Angaguk could be expected to differ from the other two sites. Again we wanted like to know how much.

Objectives

To determine spatial variability in the upper water column

To determine the area represented by the Titicaca sampling site

Strategy

In order to have a synoptic sampling and to interfere as little as possible with ongoing research on the ice, only holes that had already been drilled were used to reduce sampling time. Sampling volumes and parameters to be measured were also reduced so that only one GoFlow (or only two Kammerer) bottle(s) per hole were needed. Only one depth (3 m) was sampled per hole. Sampling was carried out on Friday March 12.

Parameters determined:

Inorganic nutrients (ammonia, nitrite, nitrate, phosphate) + Bio-silicate 1 L

Chlorophyll a (total, >5 µm, >3 µm) 3 L

Particulate Organic Carbon and Particulate Organic Nitrogen (POC and PON) 2L

Total bacteria count (epifluorescence) 0.1 L

Picoplankton and nanoplankton counts (flow cytometry) 0.01 L

Autofluorescent picoplankton count (epifluorescence) 0.1 L

Nanoplankton count (epifluorescence) 0.1 L

Microplankton count and identification (inverted microscopy) 0.2 L

DMSP + DMS 0.1 L

Sampling sites

Takatuk (2 holes), DukuDuku (2 holes), Titicaca (1 hole), Angaguk (2 holes).

Team

Karine Lacoste (UQAR), Sebastiene Roy (U. Laval), Carlos Pedrós-Alió (ICM) for sites close to the ship.

Louis Létourneau, Gérald Darnis, Alexandre Forest, Catherine Lalancette (U. Laval) for Angaguk.

Preliminary results from this sampling effort are presented in the Demers’ group report.

D) Outreach

We participated in several of the outreach activities that took place during leg 5.

i) Schools on Board.

S. Roy. “Microscopic life in the arctic ocean.” C. Pedrós-Alió. “Art and Science: Picasso and the structure of DNA.” Both: Lab demonstration of counting of microorganisms by epifluorescence microscopy. ii) Leg 5 seminar series C. Pedrós-Alió. “A bestiary in the XXI century.”

iii) Appearances and interviews with TV teams from “Cool jobs” and “Découverte.”

Both.

iv) Web page of the Goverment of Catalonia on polar issues http://dursi.gencat.net/ca/re/minisites/antartida/default.htm

C. Pedrós-Alió: Dispatches from the CCGS Amundsen.

E) Some comments on safety Despite the care with which safety issues are dealt with on board the CCGS Amundsen, things can always be improved. We have identified two questions that merit future attention.

i) Water sample transport within the CCGS Amundsen. Water samples during open water periods are taken from the CTD-rosette deployment winch on the boat and flight deck. During freeze-in periods, water samples are taken from the moon pool on the main deck or brought up from the ice through the ladder. Since different laboratories are located in the main and upper decks, no matter how the samples are taken, there is always need to transport them among different decks. The only system available for this is through steep and often slippery stairwells. It is obvious that accidents will take place sooner or later.

Suggestions: A way to circumvent this problem should be sought. Perhaps a hand-operated elevator for samples could be installed, or a toboggan put in place, or the present elevator modified so it can be used for samples under different sailing conditions.

ii) Operation of the contraption at the moon pool. The heavy right-hand arm of the contraption to hold the deployed instruments in place is held at rest by a little piece of iron that an operator has to move manually. This is not a foolproof system, as experience has demonstrated in more than one case. The risk of injuring the operator and destroying the instruments being deployed is not to be dismissed.

Suggestions: A more definitive safety mechanisms should be installed.

D) Acknowledgments

We would like to end by stating that working on the CCGS Amundsen during Leg 5 has been a pleasure and a success. This can be attributed to the following people:

Those that designed and carried out the remodelling of the old “Sir John Franklin,”

The captain and crew of the Canadian Coast Guard that run it,

The chief scientist, whose efforts have meant that we achieved ALL our goals, and

Our fellow scientists for their willingness to share, their flexibility to change plans, and their cheerful attitude throughout the leg.

Table 1. Summary of Leg 5 samples. Date Station Depths Samples 20/2/2004 Winter 1

Rosette 003a 20m, t.inv (30m), 50m, 100m, 150m, bottom (223m)

WFV team Bacteria and picoplankton (tot, <3µm), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm), 3H-Leu, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3).

CPA team Temp inv and bottom: DNA(molecular studies), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm) All depths: Chla (total), Flow cytometry, Nanoflagellates.

21/2/2004 Titicaca Ice

3m, 10m WFV team Bacteria (tot, <3µm), nanoflagellates, FISH bacteria and nanoflagellates (3 m), chla (tot, < 3µm), CDOM, DOC, protists, HPLC (3m, tot and<3). CPA team 3 m: DNA(molecular studies), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, 10 m: Chla (total), Flow cytometry, Nanoflagellates.

26/2/2004 Winter 1 Rosette 016

t.inv (20m), 50m, 100m, 150m, bottom (222m)

WFV team Bacteria (tot, <3µm), picoplankton, POC ( t inv. , bot), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3). CPA team Temp inv and bottom: DNA(molecular studies), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm). All depths: Chla (total), Flow cytometry, Nanoflagellates.


3m, 10m WFV team Bacteria (tot, <3µm) , picoplankton, nanoflagellates, chla (tot, < 3µm, <50µm), CDOM, DOC, POC, protists, HPLC (3m, tot and<3), Conversion Factor-4. CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, 10 m: Chla (total), Flow cytometry, Nanoflagellates.



WFV team Bacteria (tot, <3µm), picoplankton, POC ( t inv. , bot), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3). CPA team Temp inv and bottom: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm).

All depths: Chla (total), Flow cytometry, Nanoflagellates, Ciliates.


3m, 10m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3), lignin. CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Ciliates, Flow cytometry, Nanoflagellates, Chla (total, <50µm, <3µm), Bacterivory-11. 10 m: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates, Ciliates.

5/3/2004 Angaguk 3 m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3).



WFV team Bacteria (tot, <3µm), picoplankton, POC ( t inv. , bot), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3). CPA team Temp inv and bottom: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, Chla (total, <50µm, <3µm). All depths: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates,.


3m, 10m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3). CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, DMS/DMSP, MARFISH. 10 m: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates.

12/3/2004 Takatuk, Dukuduku, Titicaca and Angaguk Ice

Synoptic Water sampling 3m

WFV team 3H-Leu, Bacteria (tot), picoplankton CPA team Chla (total, <3µm), Flow cytometry, Nanoflagellates , DMS/DMSP



WFV team Bacteria (tot, <3µm), picoplankton, POC ( t inv. , bot), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3). CPA team Temp inv and bottom: DNA(molecular studies),

POC/PON, POP, DNA/RNA (bulk), Chla (total, <50µm, <3µm). Conversion Factor-5 (T inv only). All depths: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates.


3m, 10m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3). CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, DMS/DMSP, Conversion Factor-6. 10 m: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates.

19/3/2004 Winter 1 50 m WFV team 24h Bacteria (tot), 3H-Leu, nanoflagellates, picoplankton, chla (tot, < 3µm)


t.inv (35m), 60m (Neph), 100m, 150m, bottom (224m)

WFV team Bacteria (tot, <3µm), picoplankton, POC ( 60 m , bot), nanoflagellates, FISH bacteria and nanoflagellates (60 m and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (60 m, bot), HPLC (60 m, tot and <3). CPA team Temp inv and bottom: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), Chla (total, <50µm, <3µm), BIOLOG. All depths: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates, Ciliates.


3m, 10m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3), stable isotopes (surface). CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, DMS/DMSP, Bacterivory-12, MARFISH, Ciliates. 10 m: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates, Ciliates.

26/3/2004 Angaguk 3 m WFV team Bacteria (tot, <3µm), picoplankton, POC, nanoflagellates, FISH bacteria and nanoflagellates, chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists, HPLC (tot and <3), stable isotopes (surface), lignin.

27/3/2004 Winter 1 Rosette 81 and 82

20 m, t.inv (45m), 100m, 150m, bottom (224m)

WFV team Bacteria (tot, <3µm), picoplankton, POC ( t inv. , bot), nanoflagellates, FISH bacteria and nanoflagellates (t inv and bottom), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (t.inv, bot), HPLC (t inv., tot and <3).

CPA team Temp inv and bottom: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), Chla (total, <50µm, <3µm). All depths: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates.


3m, 10m WFV team Bacteria (tot, <3µm), picoplankton, POC ( Surface), nanoflagellates, FISH bacteria and nanoflagellates (Surface), chla (tot, < 3µm, <50µm), 3H-Leu, 3H-TdR, CDOM, DOC, protists (Surface), HPLC (Surface, tot and <3). CPA team 3 m: DNA(molecular studies), POC/PON, POP, DNA/RNA (bulk), BIOLOG, FISH bacteria and flagellates, Chla (total, <50µm, <3µm), Flow cytometry, Nanoflagellates, DMS/DMSP. 10 m: Chla (total), Flow cytometry, Nanoflagellates, FISH bacteria and flagellates.

4.2 Reports from Deming team

Cruise participants:

Jody Deming, School of Oceanography, University of Washington, Seattle, WA, USA

Shelly Carpenter, School of Oceanography, University of Washington, Seattle, WA, USA

Llyd Wells, School of Oceanography, University of Washington, Seattle, WA, USA Llyd Wells The major focus of my work has been to test the hypothesis that particle-associated bacteria are disproportionately responsible for viral production in the water column during the oligotrophic Arctic winter. Toward that end, I collected near-bottom waters (principally from the Moon Pool) to measure size-fractionated viral production (using Wilhelm et al.`s dilution method) as a function of SPM concentration and composition (analyses to be performed by Pascale Collin and Al Mucci`s laboratory). For most of my work, I also measured the protistan grazing rate on bacteria (by the dilution technique), viral-induced mortality (as opposed to viral production, using yet-another dilution technique), the frequency of actively-respiring bacteria (in some cases, with size-fractionated samples), and lysogenic induction (using Mitomycin C under most circumstances, as well as novel inducing agents). Samples were taken for analysis of DOC (by Lisa Miller`s group) and POM. In total, 8 experiments were performed with near-bottom water: 4 using the Moon Pool rosette, 2 with a bottom-tripping Niskin (thanks to Tara Businski and Sylvain Blondeau, and including one at Angaguk, with additional thanks to Louis Létourneau’s team) and 2 from sediment traps deployed off the bottom for 1 day at Takatuk (thanks to Marek Zajaczkowski, Wojtek Moskal, Noel Green, Bernard Leblanc and Christine Michel`s team).

Although most of my effort was focused on the water column, I worked on some ice samples as well. I undertook measurements of viral production in winter-time sea-ice on one occasion, trying to mimic in situ conditions of salinity and temperature as closely as possible. I also designed an experiment to measure how viral production is affected by the freezing of water, a process expected to increase contact rates (and presumably, therefore, infection) between bacteria and viruses (e.g., by brine exclusion; thanks to Takashi Ota, Shinya Yamamoto and Noel Green). For comparative purposes, Andrea Riedel and I made parallel grazing measurements (using the FLB and dilution methods, respectively) of bottom ice samples collected as part of Andrea`s work (and Christine Michel`s program). Last, sporadic samples were taken of specific ice horizons and, in one case, a depth profile was made to examine virus concentrations in the ice (and, for the depth profile, in coordination with bacterial and protistan measurements by Shelly Carpenter and Takashi Ota, respectively). Finally, I made several attempts to cultivate heterotrophic bacteria, using unusual methods, incubation conditions (e.g., subzero temperatures of –5 to –20 C, hydrostatic pressure of 600 atm), and diverse sample types. The latter included particle-rich water, thin sections of ice from the anomalous frazil layer, usually in the upper 30 cm (thanks to C.J. Mundy), and brinecycles from ridge formations (thanks to Carrie Breneman and Christina Blouw). Shelly Carpenter

Sea-ice cores were collected weekly at the Takatuk site throughout Leg 5 to assay specific ice horizons through the wintertime (Legs 3-5) for various bacterial parameters. CJ Mundy assisted with the coring, which was done with the coring equipment of Dave Barber. Three ice horizons, each 10 cm thick, in the upper portion of the ice cores were selected for study in order to track the microbial populations encased within them through the winter season and increasingly extreme conditions: the 20-30, 40-50 and 60-70 cm sections as measured from the ice surface. These sections were taken in triplicate (from three separate ice cores in the same coring plot) and processed for a standard set of measurements: total bacterial counts, specific sub-community counts by fluorescent in situ hybridization (FISH ), DNA analyses by tRFLP, and concentration of extracellular polysaccharide substances (EPS) using two methods (to get both dissolved and particulate EPS). All samples were processed shipboard in the Aft Labs, taking full advantage of the Cold Lab (set at 2°C ± 2°C) and Freezer Lab (set at -18°C ± 2°C), to the stage of sample-freezing for shipment and further analysis in the home laboratory. Several of the sections were subdivided for assays of extracellular enzyme activity (EEA) and the fraction of respiring bacteria (CTC-staining cells in 24-h incubation at simluated in situ conditions) by Jody Deming.

A comparison of EPS methods used shipboard was made with Andrea Riedel. EPS controls (shipboard vs freezing) and some brine testing (on ice sections melted into seawater vs brine) were included when ice was available. One full ice-core profile was obtained in the last week and sampled for total bacterial count and DNA analysis at every other 10-cm horizon. Llyd Wells processed subsamples for viral abundances, Jody Deming incubated other subsamples for respiration assessment using CTC, and Takashi Ota was given melted subsamples for analysis of protist presence and abundance.

All of the ice sections above were melted in a concentrated brine solution, made from Instant Ocean (a commercially available mix of sea-salts). For ice sections with in situ temperatures above –15°C, the salinity of the melting solution was adjusted so that the final salinity of the melted sample was equivalent to the salinity of the in situ brine inclusions for that section. Due to a limited supply of Instant Ocean on board, ice sections with in situ temperatures below –15°C were treated as if they were –15°C sections. The full profile during the last ice sampling was melted in recycled 0.2 um-filtered brine solution (bacteria-free, but not organic-free). Appropriate brine salinities for the ice melts were

calculated from measured in situ temperatures and bulk salinities of the ice sections collected. A full profile of temperature and salinity was obtained on a separate ice core from each weekly ice-coring outting to enable these calaculations. CJ Mundy, with help from Lisa Miller acquired the termpature readings for us, while accurate salinities were determined from CJ’s hand-held salinometer. Temperature data from the Takatuk meteorological site were also taken to correlate with the temperature measurements made at the ice-coring plot. 4.3 Cruise report of Japanese CASES (Microzooplankton group) Participants: Takashi Ota (Ishinomaki Senshu University, JAPAN: [email protected]), Shinya Yamamoto (Soka University, JAPAN: [email protected])

General objectives:

Microzooplankton are recognized to be one of the conspicuous components of planktonic assemblages in marine habitats. They play the roles of primary consumer of pico- and nano-sized producers. In addition, it has been understood that they release a significant fraction of nutrients.

Pelagic microzooplankton are known to be essential components of the Arctic pelagic food web during summer period and they are considered to be pivotal members of polar marine food webs as in low latitudes. Their winter dynamics and activities, however, are poorly understood. In the winter cruise of the CASES 03/04 program we are focusing on (1) how microzooplankton overwinter when phytoplankton production is negligible and (2) how they function in the Arctic winter ecosystem. For this purpose the following samplings and experiments were carried out during Leg 5.

1. Water sampling for Microzooplankton succession of and community structure Surface water samples were collected every 6 days from three depths (3, 5, 10m) at the Titicaca site using a 5L Go-Flo bottle. For enumeration of micro-sized plankton (ca. >10 µm), 1000 ml of sea water was fixed with acid Lugol’s solution (2% final concentration). To distinguish plastidic and non-plastidic cells under the epifluorescence microscope, another 100 ml of sample was fixed with glutaraldehyde (2% final concentration) and was filtered onto black Nuclepore filter with pore size of 0.8 µm after staining with 4’,6-diamidino-2-phenylindole dihydrochloride (DAPI). Water samples from six additional depths (10, 25, 50, 100, 150, 200m) were also collected monthly at the moonpool with a RMS (Rosette Multi Sampler). In preliminary observation on board, the sample obtained on 12 March from Titicaca site revealed that the autotrophic ciliate Mesodinium rubrum was the most abundant protist (more than 1,000 cells/L; Fig. 1) among not only the ciliate community but also total micro-sized organisms in the top10 m of the water column under the sea ice. These values are comparable to those reported in temperate oceanic waters. Fluorescent microscopy indicated that the cells retained chlorophyll and therefore the capacity for photosynthesis (Fig. 2). These results suggest that Mesodinium rubrum may contribute significantly to primary production under the very low light conditions in the Arctic winter. On the other hand, heterotrophic ciliates were present only in very low abundance, less than 100 cells/L.

Distribution of microzooplankton and their possible prey in sea-ice Sea-ice cores were collected every week at the Takatuk site to measure vertical distribution of microzooplankton, mainly protozoa in sea ice. The bottom 60 cm of the ice core were cut into 7 sections (bottom-5, 5-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm) and then melted in acid Lugol’s solution (ca. 2% final concentration) after crushing into small pieces. In some occasions, a depth profile of their prey abundance (bacterial and nanoflagellates) of the whole ice core was determined by melting samples at around 10 degrees temperature (without brine water added). Preliminary results of bacterial abundance and percentage of dividing cells on 21 March are shown in Fig. 3a, b.

In addition, some ciliates containing several cells (15 -25 cells) of small algae (3-5 µm), probably in their food vacuoles, were found in the samples from the bottom−10 cm and 10−20 cm of the ice core collected on 14 March (Fig. 4). These ciliates should therefore be herbivorous or mixotrophic. These facts indicate that herbivorous activity of the microzooplankton has already begun in the lower part of the sea ice at this time.

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3. Dilution Experiment (Measurement of grazing rates of microzooplankton) In order to examine microzooplankton grazing rates, dilution experiments were carried out every 6 days from 27 Feb to 25 Mar. Forty liters of water were collected from 3 m depth in Titicaca using 5L Go-Flow bottles. Duplicate dilution treatments of 0.25, 0.5, 0.75 and 1.0 x natural seawater were prepared in 2.4-liter polycarbonate bottles with filtered sea water (FSW). FSW was obtained by gravity filtration with the in-line filter holder equipped with GF/F filter. Incubations for the dilution experiment were performed for 24 hours in a dark room where temperature was kept at around 0 oC. Microzooplankton grazing rates were calculated by fluorometric analysis for chlorophyll a. For determination of chlorophyll a concentration, water samples (300-500 ml) were filtered through 25-mm GF/F filters and Nuclepore filter with pore size of 2.0 and 10 µm with low vacuum pressure (<100 mm Hg). The filters were immediately soaked in 7 ml of 90% acetone, with pigments extracted in the dark for 24 hrs. Chlorophyll a concentration was determined with a Turner Design fluorometer on board. Grazing rates of microzooplankton on total phytoplankton were near-zero or negligible (-0.34−0.05 d-1) from the end of February to mid-March. Toward the end of March, rates increased from 0.25 d-1 to 0.5 d-1 with increasing chlorophyll a concentration (Fig. 5). These results may show that micrograzers responded to the phytoplankton increase with a time lag of only a few weeks.

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4. Measurement of in situ growth by the cell cycle method The time-serial samplings were conducted on 2-3 March and 19-20 March from the 10- and 20-m depths at the Moonpool, where 12 liters of seawater were collected with a Rosette sampler or Go-Flo bottle at 4-h intervals over 24 h. A 2-liter subsample was fixed in 2% acid Lugol’s solution and then concentrated to < 100 ml by reverse filtration. The rest of the seawater (ca. 10 liters) was concentrated to < 100 ml by using 100-µm nylon netting and then fixed with modified Bouin’s solution (final concentration of 10%). Fixed samples will be stained on filters by the quantitative protargol staining

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(QPS) method. In situ growth activity will be determined by the principle of the cell cycle method on the basis of the fraction of cells in each cycle phase. 5. Continuing routine sampling 5-1. Hydrobios net tow for Zooplankton

(1) Live tow: We continued the weekly net tow sampling using the Hydrobios net (220-100m, 100-10m) for comparison to swimmers with particulate matter in the long-term sediment traps. Each sample was divided into two parts after concentration on a 330-µm nylon mesh: one was fixed with 5 % buffered formaldehyde immediately and the other was frozen at -80oC. (2) 24 hrs time series sampling: We also conducted sampling every 4 hours throughout 24 hours by using the Hydrobios net (220-10m) to investigate the diel changes in gut contents of chaetognaths. The samples were fixed immediately with 5 % buffered formaldehyde. 5-2. Suspended POC (d13C), PON (d15N) analyses To determine seasonal changes in sinking processes of particulate organic carbon and nitrogen, twenty liters of seawater were collected from 6 depths (10, 25, 50, 75, 200 and 220 m with a Rosette Multi Sampler) at the moonpool and fifteen liters each from 2 depths (3 and 10 m) at the Titicaca site. Particles in the collected waters were filtered onto pre-combusted Whatman GF/F glass fiber filters and stored in a deep freezer (-80oC). Acknowledgments We are grateful to the following colleagues for collaboration in sampling during Leg 5: Christopher (CJ) Mundy, Eric Braekevelt, Dan Leitch, Lisa Miller, Shelly Carpenter and Chris Konig for ice-core samping at Takatuk, Eric Braekevelt, Dan Leitch, Sebastien Roy, Carlos Pedros-Alio, Lisa Miller, Llyd Wells and Noel Green for Go-Flo sampling at Titicaca, Louis Letourneau, Alexandre Forest, Gerald Darnis, Catherine Lalancette and Tara Businski for Hydrobios net sampling in the Moonpool, and Nikolay Vysotsky and Sylvain Blondeau for CTD-RMS operation in the Moonpool. We are also grateful for the highly professional assistance provided by the captain, officers and crew of the Canadian Coast Guard Amundsen during Leg 5. We also specially thank the chief scientist for her kind coordination of our sampling schedule. We also thank Dr. Carlos Pedros-Alio for his correcting of our English.

5. Pelagic food web: structure, function and contaminants 5. 1 Contaminants Research objectives: The overriding question this project hopes to answer is how climate variability in physical forcing and the biogeochemical response to this primary forcing will affect organohalogen and trace metal contaminant cycling. Ultimately, we propose to relate changes in delivery and biogeochemical cycling of these contaminants to their levels in fish, marine mammals and the people who consume these tissues as part of their traditional diets. Mercury, which cycles globally in the atmosphere, is deposited uniquely in polar regions through mercury depletion events (MDEs; oxidation of Hg (0) to Hg (II)), and these appear highly sensitive to ice and ocean climate variables. Detailed mass balance and fate studies will be conducted to formulate a mass balance model for mercury in the Beaufort Sea marine system. In conjunction with the work being done to quantify vertical and organic material fluxes, such a model will form an interpretive basis for monitoring

components of the system and interpreting proxy records. To conduct these mass balance studies we envision making the following measurements for mercury and organohalogen contaminants in ocean water: water and suspended sediment from the Mackenzie and other smaller rivers, near surface air, snow and ice cores, permafrost, and lake and marine sediment cores. Areas frequented by Beaufort Sea beluga will be specifically targeted for benthic and pelagic food web (stable isotopes and fatty acids) and contaminant studies. Water δ18O and salinity measurements will also be made to distinguish between freshwater sources (runoff and sea-ice melt) such that the relative roles of import of Hg from the drainage basin versus Hg cycling through ice formation and melting can be evaluated. We have no results to report at this time, as the laboratory required for trace contaminants analysis is not compatible with a marine vessel. All samples will be transported to Winnipeg for analysis. Water was collected from the rosette twice per week, for a total of 12 collections. Total mercury samples were collected in duplicate at eight depths (total of 216 samples, including 24 blanks), along with samples for salinity and δ18O (total of 96 samples). Methyl mercury (MeHg) samples were also collected in duplicate every fourth sampling (51 samples, including 3 blanks). Surface water was collected from an outdoor site eight times during Leg 5. A total of 52 total mercury samples (including 12 blanks), 21 MeHg samples (including 3 blanks) and 20 salinity and δ18O samples were collected. Ice cores and snow were collected once per week. Samples were melted and bottled for salinity and δ18O (total of 19 samples), and total mercury (total of 50 samples, including 12 blanks). Duplicate MeHg samples were collected every second sampling (total of 18 samples, including 2 blanks). A high-volume air sampler was set up at the meteorological site about halfway through Leg 5. A total of three air samples were collected (1 per week). High-volume water pumps were deployed under the ice approximately once per week at four depths. Two of the pumps were new and untested in the field. One of the new pumps leaked on its first deployment, but worked well once the leak was repaired. The other new pump appears to have some software problems, as it shuts down before pumping the programmed volume. Nonetheless, 13 samples were collected (including 2 blanks). Biotic sampling included zooplankton and fish. We had no success deploying fish and amphipod traps under the ice, but the zooplankton groups often caught arctic cod in their plankton nets, which they donated to us. A total of 16 arctic cod were collected. In addition, 11 zooplankton samples were collected. These were sorted into groups (Calanus, Euchaeta, etc.) and frozen for transport back to Winnipeg. Some things that could be improved for subsequent legs or other overwintering projects include the choice of snowmobiles and the availability of refrigerator space. The smaller snowmobiles (Bombardier Tundra) did not perform well in very cold temperatures (< -−30ºC). The larger snowmobiles performed better under the conditions experienced on this leg. In addition, we had a lot of trouble finding adequate room to store our samples. There was adequate room during this leg to store frozen samples (they can even be stored outside), but there was little space available to keep samples cool but not frozen (5-10ºC). Space of any kind is very limited on the ship, but it would be nice to see a refrigerated container or walk-in cooler. The existing refrigerated lab space is heavily used as a lab, leaving minimal storage space within it. 5.2 Food web structure Cruise Participant: Tara Businski

Introduction

The goals on this leg were (1) to determine the source (i.e. terrestrial-based or marine-based) of food material in the diets of zooplankton, including the composition of the suspended particulate matter (SPM) to obtain biomarker end-member values for available food particles, (2) to determine the food sources and feeding relationships between hyperbenthic zooplankton using fatty acid biomarkers, CNP ratios, and stable isotopes, and (3) to examine small-scale spatial distribution of zooplankton using Video Plankton Recorders (VPR) and to calibrate video data with quantitative net tows.

Based upon a sparse existing literature for the Beaufort Sea Shelf (BSS) and preliminaray data from the CASES02 cruise, I predict that herbivorous copepods feed selectively on marine phytoplankton, whereas appendicularians and other non-selective feeders consume particles in proportion to their availability in the water column and therefore feed proportionally on more terrestrial source material than do copepods. Feeding on SPM by zooplankton affects the fate of those particles because zooplankton repackage small, slowly-sinking particles into large, fast-sinking faecal pellets and soma. Pellets and diatoms sink at from 10's to 100's of m d-1, while small (i.e. < 0.2 µm diameter) lithogenic particles sink at < 1 m d-1. This means that food particles that would otherwise be remineralized in the water column may be repackaged into faecal pellets that sink rapidly to the bottom. Hyperbenthic zooplankton live just above the sediment surface and are not adequately sampled either by nets or benthic samplers so their food webs are poorly understood. This community has a potentially large impact on the fate of organic matter reaching the benthos, but it is largely unstudied.

Video plankton recorders can resolve objects ranging in size from diatom chains to adult copepods. These images will be used to determine the fine scale vertical distribution of mesozooplankton and their prey. The VPR package includes a SeaBird CTD and in situ fluorometer, so that zooplankton distribution can be related to hydrographic and phytoplankton vertical structure.

Samples Collected (all samples will be analyzed at Memorial University) Samples were collected every 6 days from 20 Feb 2004 through 29 Mar 2004.

Goal 1 SPM: Water was collected from the rosette at 2-3 depths (bottom, temperature inversion or nephaloid layer, and 100m) and up to 15 L from each depth was filtered onto an ashed GF/F filter. Surface water was also collected from a hole in the ice at Titicaca. These samples will be analyzed for lipid classes and fatty acids to distinguish terrestrial and marine food sources available to zooplankton.

Zooplankton: Water column zooplankton were collected from a 220m to surface tow using a tucker net on the same day as rosette water was collected. I picked up to 40 Calanus hyperboreous C6 females, C. hyperboreous C4, C. glacialis C4-6, Eukrohnia hamata, Oikopleura sp., Euchaeta sp. and Metridia sp. when abundant. The first 20 animals of each taxon were measured and staged. These samples will be analyzed for lipid classes and fatty acids to distinguish terrestrial and marine food sources. If abundant, up to 20 additional animals were picked for CHN analysis.

Faecal pellets: Faecal pellets from water column zooplankton were collected every 6 days using a 50µm-mesh phytoplankton net towed 220m to 0m and sediment traps deployed every 8 days at 50m. Codend contents were sieved onto a 50µm-mesh disc and frozen for lipid class and fatty acid analyses.

Goal 2 Near bottom water: A specially designed bottom-tripping Niskin bottle was used to collect near bottom water. This water was filtered and will be used for analysis of elemental stoichiometry, specifically for POC, PON, and POP. These ratios will be compared to those of the hyperbenthic zooplankton. This water will also be analyzed for lipid classes and fatty acids to distinguish marine food sources (namely diatom vs. flagellate/bacteria) and terrestrial food sources available to hyperbenthic zooplankton.

Inorganic nutrient samples and pigment samples were taken by Karine Lacoste and bacterial abundances were measured by Sebastian Roy.

Animals: Hyperbenthic zooplankton were collected in traps baited with meat scraps the same day the bottom-tripping Niskin was deployed. These animals, like the near bottom water, will be analyzed for lipid classes, fatty acids, stable isotopes, organic carbon, organic nitrogen and organic phosphorus.

Goal 3 Two video plankton recorders (the autoVPR and VPR) were deployed. Zooplankton in these videos will be identified and fine-scale vertical distribution of mesozooplankton examined. One 24-hour zooplankton sampling was conducted on 13-14 Mar 2004 which included an autoVPR tow every 4 hours and 2 VPR tows spaced 12 hours apart.

5.3 Laval University Zooplankton Team Cruise report Cruise participants : Louis Létourneau, Alexandre Forest, Gérald Darnis, Catherine Lalancette General objectives :

As the Arctic winter progress, the main interest of our group is how evolve the marine biota in a complete frozen environment. We focus on the global structure of mesozooplancton community and on Arctic cod (total biomass and spatial scale comparison). The sampling of this biota is traditionnaly hard to be done in winter, first because of the harsh conditions that prevail in the Arctic at this time of the year, but also because the water is almost inaccessible under the ice that acts as barrier. That’s why our knowledge of zooplankton overwintering strategies is also very limited, even for well known species like Calanus sp. Thus, the goal, in addition to the total biomass study, is the understanding of annual cycle processes by maintaining the continuity in the measurements of copepods reproduction, faecal pellets production, lipid content and respiration rates; and feeding and physiological state of Themisto libellula and Arctic cod. The overwintering position of the NGCC Amundsen within CASES 03/04 expedition offers under-ice sampling opportunities like never before. As it will be explained, our marine biological group could work from 3 different positions during this wintertime of CASES 03/04: the moonpool station within the ship, the ice station Dukuduku (just outside the ship), and the ice station Angaguk (near the Horton River).

Moonpool sampling :

The moonpool aboard the ship is a unique equipment that allows us a continuous sampling schedule during winter. During leg 5, our team continued the weekly moonpool sampling (stratified, stock assessment and live tows) using both the Hydrobios (200µm mesh) and the single Tucker square net (200µm mesh). We also sampled once at 4 hour intervals for a period of 24 hours to evaluate variation in mesozooplankton diel vertical migration. We didn’t experiment technical problems with the Hydrobios in leg 5 instead of leg 4. A additionnal point that can be mentionned with the Hydrobios description is how efficient it became to catch fish in mid-march. As it will be explained further, the single use of the Hydrobios caused 81% of the total fish caught during leg 5. This surprising number demonstrate the very poor efficiency of traditionnal fish net or trap when they are used in an frozen environment. Moreover, the other 19% were caught either with single square or ring net and even with amhipods traps. (Figure 1 : Retrieval of the Hydrobios by Gérald, Catherine and Shinya)

Dukuduku ice station sampling : We continued at Dukuduku ice Station the weekly zooplankton sampling by the deployment of a 0.5 m diameter ring net with 250µm-mesh net coupled with a 10 cm diameter sock, 50µm-mesh. A CTD cast using a SBE 19 was also done at the same time. We also continued the horizontal and oblic tows with the use of a double square Tucker net (200µm 1m2 and 500µm 1m2) equiped with a 10 cm diameter sock (50µm-mesh). We usually used Skandic Ski-Doo to perform this tow, but since we tried it and succeed with the BR last march 18th, we began to use it every time. By this way, we could go at the required speed (3 knots). Moreover, we could at least reach the bottom to do a real complete oblic tow (bottom-surface), a thing that never happened for the previous samplings (with the ski-doos, we were safer and we never drop the Tucker net more than 60-70m from the surface). In addition to net tows and CTD casts, the Dukuduku ice station served at multiple occasions to test the use of a hoop net to catch fish. As previously mentionned in the zooplankton leg 3&4 cruise report, the single use of vertical tows in the moonpool was not enought to catch fish for our studies. That’s why we tried to improve the fish sampling method with the deployment of this hoop net acting as a fish trap. A first fish trap was lost with the sudden break of the rope that was installed at Dukuduku since last December, but after we had another one thatwe used several times after (without any success). As you now know, almost all the fish that we caught during leg 5, were caught within the Hydrobios deployment as it was mentionned. (Figure 2 : BR is pulling the net from one hole to another at Dukuduku) Angaguk ice station sampling : The beginning of leg 5 reserved us a terrible surprise when the first time in this leg we tried to do an under-ice sampling, we realized that our rope was frozen again (for more details about how hard it was to install this rope, read leg 4 cruise report). On the other hand, because we didn’t want to do a special emphasis on Angaguk ice station like we did in leg 4, we chose instead of that to fit the re-installation

of the rope witin the time that was hebdomary allowed to Angaguk ice station (not more). Thats why, with another succession of weather difficulties & mechanical failures, the first under-ice horizontal tow for leg 5 was performed only on march 16th. As problems we experimented in leg 5 with this Angaguk station, we can mention briefly the blizzard and the broken BR that forced us to stay 3 days off at Angaguk; and the so frequent Jiffy failures that caused again a lot of lost time. But at least, we could continue the time-series sampling at Angaguk like the vertical tow schedule (0.5 m diameter ring net with 250µm-mesh net coupled with a 10 cm diameter, 50µm-mesh) and the CTD (SBE 19) cast schedule. The under-ice horizontal and oblic tows were done again with the use of the double square Tucker net (200µm 1m2 and 500µm 1m2) equiped with a 10 cm diameter (50µm-mesh). Those tows were performed with Ski-Doos even if we couldn’t reach the optimal speed of 3 knots. (The BR was not sent away the ship since the problems it experimented away.) At least, we could continue the sampling serie at Angaguk. Finally, in addition to zooplankton nets, we deployed one time the fish trap at Angaguk, but with the lost of the first one at Dukuduku in the first week, we bring back the Angaguk fish trap to install it at Dukuduku. (Figure 3 : Catherine fixing the fish trap that never caught fish.) LabWork and experiments : Instead of leg 4, a real emphasis was given to labwork and experiments in leg 5. We fastly began eggs production, lipid content and respiration rates on copepods at the beginning of this leg. At this time, the key specie C. hyperboreus was clearly on a spawning curve, but the question mark was if it was ascending or descending. More measurements from leg 6&7 are needed to confirm the tendency, but preliminary results reveal that this specie is actually on it’s peak of spawning, because we can see a high density of eggs (probably from C. hyperboreus) in our samples from horizontal under-ice tows. Another surprise that we had during leg 5, was the beginning of the spawning of the key omnivorous specie Metridia longa in early march. This spawning event is a great thing because the annual cycle of this specie is a big question mark in oceanographic biology. But, visual inspection shown us that these first eggs were not viable and degenerated rapidly in our incubator. Therefore, the continuity of eggs production experiments in the next weeks are cucial to monitor the apparition of viable M. longa eggs. Finally, the third key specie of Arctic zoopankton, Calanus glacialis, did not spawn yet, but will probably do it soon when the food availability will increase enough near the surface. (An actual hypothesis wants that C. glacialis feed on C. hyperboreus eggs that accumulate at sea-ice interface.) Morevover, we began to see since two week some C. glacialis in a ‘ready-to-spawn’ gonadic stage (stage 4). (Figure 4 : Gérald setting up respirometry chambers) Concerning the lipid content & dry weight measurements of copepods, those procedures were done on the required schedule in leg 5 (once for dry weight & twice for lipid contents). Furthermore, specie-specific faecal pellets production were performed several times this leg in coooperation with the eggs production. These first experiments shown us prelimiray results on the 3 key species mentionned above. The two Calanus didn’t produce faecal pellets yet and demonstrate thus that they are still in a

diapause mode (living on their lipids reserve). On the other hand, the omnivorous M. longa is feeding all year long and shown feacal pellets production even in winter. But, the defecation rate of this specie was very low in mid-february/march with around production of only 1 pellet.ind-1.d-1. The specie-specific faecal pellets production experiments that were realized this leg are really trials experiments. Thus, it was achieved only on adult stades of mentionned species and depending on the feasability of extanding this experiment to copepodites stades and even small species (Pseudocalanus spp., Oithona sp. & Oncea sp.), maybe it will become a standard protocol included with the other ones in our team. Finally, we can provide here (before the Arctic cod ‘subject’), a resume of the amphipod specie Themisto Libellula that were caught and preserved for later analysis. All of the Themisto caught during this leg were caught within live tows in the Moonpool either with Hydrobios or Square Tucker net. Table 1 : Analysis on Themisto Libellula during leg 5

The Arctic Cod ‘enigma’ On previous legs, 42 Arctic cods were caught in leg 2, 15 in leg 3 and only 3 in leg 4. But, in leg 5, we caught the incredible number of 161. Only 4 of these all 161 cods were juvenile stages around 70mm. All the other cods seam to be first-year (YOY) between 120 and 180mm. Further analysis (otholimetry) must be conducted to confirm this affirmation. The Hydrobios caused the catch of 131 cods (81%), 2 cods were caught in a vertical tow at Dukuduku (February 29th); and the 28 other cods were caught by Tara Businski from Memorial University within Tucker net or amphipods traps in the moonpool. The details of the exact dates for the fish caught by Tara was unfortunately not compiled. On the other hand, we present here the details of how the fish were caught within the Hydrobios. You can see clearly the abundance peak around march 18th. This graph DO NOT confirm that more cods were in the water at this time, but only outlook how we observed a kind of tendancy in the fish ditribution under the ship. Further analysis must be conducted by EK60 (echosoundar) experts to confirm the horizontal&vertical migration of fish that could occur within leg 5 and that resulted in this pattern. Preliminary results shown that the fish can be between the 140&160m depht. (Figure 5 : Louis is proud of the St-Patrick’s catch of Arctic Cod)

Number of animals 19 3 6 Analysis performed Lipid content Dry weight Full gut

Figure 1 : Catch of Arctic cod with the Hydrobios during leg 5

Conclusions and recommendations for leg 6: Leg 5 was again a true experimentation of the Arctic winter for the Laval zooplankton team. On the other hand, we could benefit of the winter experience of two members from our team that were here in leg 4. This experience provided us a basis of how feasable was the sampling & experiments schedule with a team of 4 people facing two ice stations ‘not so easy’ samplings, moonpool sampling and continuous labwork. We did not have it easy again and we realized soon how much energy we will have to inject to continue our activities. But we’ve been really realistic during leg 5, and we decided fastly to keep a balance between the outdoor & indoor activities. That’s why we decided to forget about the fish nets under-ice deployments (gill net & fish trap). First, because of the very very poor efficiency they gave us when we deployed them (0 catch); and secondly because of the time (especially the gill net) they require for deployment & retrieval. Moreover, the Hydrobios was more efficient to point out both the layer and fish abundance compared to traditionnal fish nets. Thus, in addition to the great sunlight increase we had since 3 weeks, we decided to do only one-day trip at Angaguk after we passed there another rope. Concerning the outdoor zooplankton samplings, the use of the BR proved it’s efficiency for the horizontal and oblic tows. Unfortunately, the BR was not driven away the ship since mid-march and therefore, we had to use Ski-doos again at Angaguk for those tows. Finally, about the experiments and labwork, we can be proud of how we managed it during leg 5 compared to leg 4, but we still miss time to do everything on a perfect schedule, especially for the Themisto analysis. Thus, here are some recommendations for leg 6. The Angaguk Ice station must be maintained, but visited only twice a week for a one-day-trip. One time for the horizontal & oblic tow (with the BR); and a second time to perform a ring net/CTD cast. The Dukuduku Ice station must received the same treatment. Therefore, the holes will be kept opened regularly and no time will be wasted in overnighting. The deployment of gill nets or fish traps can be done only if extra-time is available. No priority must be assigned to those activities. Also, we do not recommend the extension of the distance between the two holes at Dukuduku, because the ship is supposed to leave it’s overwinter position at the beginning of leg 7, and thus, less than 6 weeks does not justify this action. A first priority in leg 6

can be instead of those activities the beginning of a bi-weekly sampling of the Hydrobios (one during the night, and one during the day). The prority must also be put on experiments. With the increase of biological activity (chl a) we saw since a couple of weeks, it will be very interesting to monitor correctly the response & dynamic of mesozooplankton community to this situation. Therefore, Gérald Darnis and Anna Prokopowicz will need extra help to conduct there experiments on copepods and amphipods. Finally, concerning the Arctic Cod, the continuous monitoring of the EK60 can be very useful to see the fish abundance since we matched the appearance of dark-red/brownish lines between 140&160m to fish shoals. Thus, special sampling effort in the moonpool can be done to confirm that when this echosounding pattern appears.

Keep the Spirit!

Table 2 : Summary of the activities of Laval Zooplankton Team within leg 5 of CASES 03/04

Moonpool Ice Station Dukuduku Ice Station Angaguk LabWork

Hyd

robi

os

Ver

tical

Tu

cker

Net

CTD

Rin

g N

et

Hor

izon

tal

Tu

cker

Net

Obl

ic

Tu

cker

Net

Hoo

p N

et

(Fis

h tra

p)

CTD

Rin

g N

et

Hor

izon

tal

Tuck

er N

et

Obl

ic

Tuck

er N

et

Hoo

p N

et

(Fis

h tra

p)

Eggs

pr

oduc

tion

Faec

al

pelle

ts

prod

uctio

nR

espi

ratio

n ra

tes

Lipi

d co

nten

t

Dry

Wei

ght

2004-02-21 X X X X X 2004-02-22 X X X 2004-02-23 X X 2004-02-24 X X X X 2004-02-25 X X X X X 2004-02-26 X X X X X 2004-02-27 X X 2004-02-28 X X X 2004-02-29 X X X X X 2004-03-01 X 2004-03-02 X 2004-03-03 X X

Blizzard & broken BR @ Angaguk

X 2004-03-04 X X X X 2004-03-05 X X X X X 2004-03-06 X X X X 2004-03-07 X X X X 2004-03-08 X X X X 2004-03-09 X X X X 2004-03-10 X X X 2004-03-11 X X X X 2004-03-12 X X 2004-03-13 DVM X 2004-03-14 DVM X X 2004-03-15

New rope under the ice @ Angaguk X

2004-03-16 X X X 2004-03-17 X X X 2004-03-18 X X X X X 2004-03-19 X X X 2004-03-20 X X 2004-03-21 X X X 2004-03-22 X X X 2004-03-23

2004-03-24 X X 2004-03-25 X 2004-03-26 X X 2004-03-27 X X X X 2004-03-28 X X 2004-03-29 X X X 2004-03-30 X

Blizzard = Stuck on the ship

6. Water column carbon geochemistry Cruise participants: Pascale Collin (McGill University) and Lisa Miller (Institute of Ocean Sciences) In our continuing efforts to comprehensively described the carbon fluxes through the shelf system of the eastern Beaufort sea, we collected full water column profiles of pH, dissolved inorganic carbon (DIC), alkalinity (AT), and dissolved organic carbon (DOC; filtered through combusted GF/F filteres) every six days throughout Leg 5 (cruise 0402). We also collected suspended particulate matter (SPM) samples, ice cores, and gas samples. On each moonpool Day 1, we collected water from the 08:30 chemistry cast (shortly after the 06:30 microbiology and primary production cast finished sampling) at 9 depths (20, 25, 50, 75, 100, 125, 150, 175 m, and the bottom, about 225 m) for pH, DIC, AT, and DOC. We also collected TOC (total organic carbon -- i.e. unfiltered) samples from cast 030, and methane samples from casts 017 and 082 for Fiona McLaughlin (at 20, 50, 75, 100, 150 m, and the bottom). On moonpool Day 2 surface water was also sampled from 3 m at Titicaca for pH (except on March 16th), DIC, AT, TOC, salinity, and Oxygen-18 (O-18, every two weeks, when it had also been collected from the moonpool rosette cast the day before by Nykolay). We also collected some surface water samples for C-13 from Titicaca on March 10 (organic only) and 16th (both organic and inorganic).

Spectrophotometric analysis of pH samples was completed within a few hours of sample collection. **With the exception of the samples collected at the last rosette and surface casts, all of the DIC and alkalinity samples collected on this leg, as well as 12 samples collected on Leg 4, were analyzed (coulometrically and potentiometrically, respectively) before we disembarked. The data have not yet been quality-controlled, but a preliminary DIC profile is shown in Figure 1. The decrease at the surface is primarily related to the lower salinity (normalizing the data to a constant salinity gives higher DIC values at the surface than at depth). The maximum at 150 m appeared consistently in most of our casts and was associated with the main halocline and the level at which zooplankton were observed to congregate. Figure 1. Preliminary DIC profile (umol/kg) showing typical trends observed throughout the leg.

Pascale collected suspended particulate matter (SPM) samples at 3 different sites (i.e. moon pool, Titcaca, and Horton River). Surface waters were sampled at Titicaca and bottom water was sampled from the moon pool. Horton river was sampled in 0.5 meter of water. The big quantity of suspended particulate matter at this site permitted 6 replicates, with 3 replicates rinsed with HCl. The water samples were filtered on pre-weighed 0.3 µm micro-fiber glass filters immediately upon recovery of the rosette or within 12 hours following storage of the water in the cold room. In most cases, duplicate filters were obtained. The filters are preserved in the –80 °C freezer and will be dried by liophilisation at the university, weighed for suspended particulate matter concentration, and used for mineral analysis and sequetial extractions for minor and major elements.

In addition to water column work, Lisa collected an ice core every week (on Sundays) in cooperation with C.J. Mundy (see section 1). Full temperature profiles (every 10 cm) were taken on the core as soon as it came up, and then the core was cut into 10-cm sections, which were individually melted back on the ship. The core melts were always subsampled for DIC, alkalinity, TOC, nutrients, and salinity. We also subsampled for C-13 from the cores taken on February 29th (total organic and inorganic C only, from every second section: 0-10 cm, 20-30 cm, etc.), March 7th (particulate, as well as total organic and inorganic; from every second section), and March 14th (particulate and total; every third section: 0-10 cm, 30-40 cm, etc.). DIC and alkalinity were measured on board (except for those melts from the last core, taken on March 28th). An example DIC profile for an ice core is shown in

Figure 2. The decrease towards bottom of the core implies that the inorganic carbon concentration in the brines increases upcore. Figure 2. Preliminary profile of inorganic carbon (as a function of ice mass, not brine volume) in an ice core collected from Takatuk on March 21. Lisa and Carrie Breneman also continued sampling initiated by Owen Owens on Legs 3 and 4 from CO2 peepers frozen into the ice at both Takatuk and Bruney Island. These peepers each have three isolated chambers with silicone membranes (which are permeable to CO2) exposed to the ice. Each chamber has an outlet port at the surface, from which we collected gas samples twice each week (Wednesdays and Saturdays, Takatuk in the morning, and Bruney Is. in the evening). Those samples were analyzed on board by gas chromatography, and an example data set is shown in Figure 3. Although we still have some serious calibration and sampling issues to resolve, the general trend of CO2 levels much, much higher in the ice than in the air is very intriguing. Figure 3. Preliminary ice peeper CO2 profiles from February 28. Air samples were taken by syringe, facing upwind.

Overall, this has been an astoundingly productive leg. The Amundsen is an excellent platform for the kind of ice work we have been doing, with its combination of strong logistical support from the crew (thanks gang!), excellent laboratories, and comfortable living conditions, and we have collected an unexpectedly large number of very high quality samples. The only glitch was that we were expecting to have a heated parcol on the ice with a hole in the floor for sampling surface water, where we would be able to experiment with high resolution vertical and temporal profiling. Nonetheless, the shed at Titicaca at least allowed us to collect routine samples to complete the low-resolution profiles collected from the moonpool (with the exception that we were not able to poison our inorganic carbon samples until we returned to the ship, because the saturated mercuric chloride solution kept freezing in the pipette tip). We also want to particularly thank the logistics crew for their patience and flexibility in feeding us, routinely extending the lunch period to allow those working on the ice to have fresh, hot lunches. OTHER Participant – Travis Wert PI – John Hughes Clarke The intent of this leg was to collect data for both the C-Nav GPS receiver, and the Knudsen K320 subbottom profiler. Initial concerns were that the C-Nav would not be functional as it is only spec’d to -20 C. Also, several modifications had been made to the wiring network and those changes had to be identified, evaluated as to their requirement, and reversed if need be. To that end, the duties carried out can then basically be separated into the following subsections. Equipment reinstallation and setup The first priority was to get the C-Nav running, and logging via the Knudsen PC in the Data Acquisition Room (DAR). Fortunately, the unit was not powered down at the end of Leg 1 as had previously been suspected. The unit was operating normally. Updates to the receiver and display unit firmware took place over days 1 and 2. In the DAR, several key pieces of serial equipment had been

‘pillaged’, to include null modems, cables, and numerous gender changers. The connections were re-established using the left over bits and pieces. As well, several important connections to be employed once the ship is again underway had been removed. For instance, the cable connecting the EK60 to the depth telegram switch box was disconnected, and left hanging in the ceiling ducts where it apparently got stuck during removal. In any case, connections were made that allowed for logging of the C-Nav NMEA strings, C-Nav raw binaries, and of course the Knudsen PC logging the depth files. Equipment Checks Once everything was connected, all units operated well. The list of equipment checked includes; the C-Nav GPS, the Knudsen K320, and the Simrad EM300. The 300 was turned on and set to logging phase to test but was not used for any actual data. Again, it should be noted that the connections for many of the individual survey components were disassembled at some point prior to Leg 5. Prior to break out, an effort should be made to return the missing serial pieces and reconfigure the rack in the DAR to its Leg 1 state. Data Logging The data logging carried on with little problems. Daily files for the GPS were made as both NMEA outputs and raw binaries, capable of RINEX conversion. The K320 files were logged as only time and depth. As the important variable in this case is the depth change due to tides, there were no attempts made to utilize moonpool CTD data for sonar calibration.

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