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Y. Gratton

ArcticNet Annual Research Compendium (2011-12)

Marine Observatories

3.5 Long-Term Observatories in Canadian Arctic Waters (Marine Observatories)

Project LeaderYves Gratton (Institut national de la recherche scientifi que - Eau, Terre et Environnement)

Project Team

Network InvestigatorsAlfonso Mucci, Bruno Tremblay (McGill University); Yvan Simard (Université du Québec à Rimouski); Louis Fortier, Jean-Eric Tremblay (Université Laval)

Collaborators and Research AssociatesPeter Galbraith (Fisheries and Oceans Canada - Maurice Lamontagne Institute); Daniel Bourgault, Dany Du-mont, Magalie Lasne (Institut des sciences de la mer de Rimouski); Dominique Boisvert, Marie-Emmanuelle Rail (Institut national de la recherche scientifi que - Eau, Terre et Environnement); Michel Gosselin (Université du Québec à Rimouski); David G. Barber, Simon Prinsenberg, Gary A. Stern (University of Manitoba); Ronald Benner (University of South Carolina); Fiamma Straneo (Woods Hole Oceanographic Institute (WHOI))

Postdoctoral FellowsPierre St-Laurent (Institut des sciences de la mer de Rimouski); Alexandre Forest, Catherine Lalande, Makoto Sampei (Université Laval)

PhD StudentsBazile Kinda (GIPSA-Lab); Somayeh Nahavandian, Caroline Sévigny (Institut national de la recherche scien-tifi que - Eau, Terre et Environnement); Gerald Darnis (Université Laval)

MSc StudentsJessy Barette, Charles Brouard (Institut national de la recherche scientifi que - Eau, Terre et Environnement); Amélie Bulteau (Institut des sciences de la mer de Rimouski)

Technical and Project Staff Sylvain Blondeau, Pascal Guillot (Québec-Océan); Pascal Massot, Luc Michaud (Université Laval)

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ABSTRACT

In the past decade, we have witnessed records of Arc-tic sea ice minimal extent (Maslanik et al. 2011) and it appears that 2011 will be another record low. The ice cover is the insulation between the atmosphere and the ocean. A shrinking ice cover means that more light and more heat are going to penetrate in the Arctic Ocean and totally change the Arctic environment. The objective of this project is to monitor these changes in physical, biological and geochemical properties of the Canadian Arctic waters. In the past, we have deployed ocean ob-servatories in Hudson Bay, Hudson Strait, Baffi n Bay, Beaufort Sea and the Eastern Arctic Ocean. These ob-servatories are the oceanic equivalent of atmospheric meteorological stations. They are deployed every fall and recuperated one year later. While in the water, they record temperature, salinity, water velocity, dissolved oxygen, nutrients, light intensity, fl uorescence (an indi-cator of micro-algae biomass) and ice motion. Hydro-phones also record the vocalization of whales and other marine mammals. The data is used to describe the sea-sonal and annual variations in the Arctic environment and its local ecosystems. This, in turn, enables us to un-derstand how global warming is affecting the Arctic and how fast.

KEY MESSAGES

• The water under the ice is very active in southern Beaufort Sea: there are numerous eddies and cur-rent pulses with velocities up to 0.90 m s-1, com-pared to a background mean current of 0.05 m s-1.

• Passive Acoustic Monitoring is helping to com-plete the whole picture of marine mammal chang-ing occupation of the Arctic under fast changing ice conditions, and assess the pristine ambient noise in these habitats before the expected im-portant modifi cations in response to increasing anthropogenic activities.

• Sediment traps data confi rm that the ongoing decline in Arctic sea ice promotes the growth

of pelagic communities in the Amundsen Gulf. However, it is unlikely that the increase in the productivity of lower food web could support new harvestable fi shery resources in the offshore Beaufort Sea domain.

• Climate change will strongly affect the pattern of the underwater ambient noise levels of the sound-scape marine life such as whales, seals and fi sh are exposed to over the annual cycle. The recent analysis of a 13-month broadband acoustic record-ings from the ArcticNet observatory in the middle of Amundsen Gulf evidences the large changes in soundscape characteristics during the open water season compared to the ice-covered season. The melting of the ice will result in a longer infl uence of wind forcing on ambient noise, increasing the levels by several dB over a large frequency band-width compared to under-ice levels.

OBJECTIVES

The overall objective of this project is to monitor and document areas that could gradually see a signifi cant shipping increase in the Canadian Arctic.

• The fi rst objective of this Arctic monitoring pro-gram is to follow the penetration of Atlantic water through the Greenland and Norwegian Seas and circulating around and across the Arctic Ocean. We will also quantify the Pacifi c water trans-port, variability and water masses transformation mechanism as it reaches the Mackenzie shelf and then bifurcates into the Amundsen Gulf. Knowing what is coming will help us understand how (and when) this water is fl owing through the different straits in the Canadian Archipelago. This data is also essential to validate the large scale Arctic models that are producing the boundary condi-tions for our IRIS regional models.

• A second objective is to develop, adapt to the Arctic and exploit the new PAM (passive acoustic monitoring) technologies to monitor the frequen-tation of the hot spots by marine mammals groups

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and species over their annual migration cycle to feeding and breeding grounds. We hope to relate the changes in their use of the habitat to changes occurring in ecosystem productivity and commu-nity composition and spatial organization in re-sponse to climatic change. The characterization of the underwater noise patterns of this pristine environment of the global ocean compared to the lower latitude belt that is strongly affected by an-thropogenic activities is another secondary objec-tive, which is presently among the research priori-ties of international programs on ocean noise.

• A third objective is to investigate the seasonal and interannual variability in the productivity of the biological hotspots and their exploitation by top predators. In particular, we want to monitor the changes in nutrients availability and biological production, in relation with the reduction in sea ice cover and increasing sea water temperature.

• Our fourth and fi nal objective is to monitor the seasonal variability in the timing and magnitude of vertical carbon fl uxes. In the past, it was ob-served that the sedimentation rates (from sedi-ment traps) are highly seasonal and sometimes infl uenced by current pulses. We plan to relate the changes in vertical carbon fl uxes to the reduction in sea ice cover and increasing sea water tempera-ture, and, in turn, to the changing biological pri-mary and secondary productions.

INTRODUCTION

In the past decade, we have witnessed records of Arc-tic sea ice minimal extent (Maslanik et al. 2011) and it appears that 2011 will be another record low. The Arctic Ocean is the world largest source of freshwater. The Canadian Arctic Straits (plus Fram Strait) connect the waters of the Arctic Ocean to those of the Atlantic. Arctic surface water moves via these straits into the Labrador Sea, thereby stabilizing a global imbalance in precipitation minus evaporation between the Pacifi c and Atlantic Oceans (Wijffels et al.1992). Fluctuations

in the fl uxes of freshwater through the Archipelago may have global signifi cance for climate through their infl uence on deep convection in the Atlantic sector (Melling 2000). The Arctic is changing more rapidly that the predictions of the most pessimistic models. The ice cover, i.e. the insulation between the atmos-phere and the ocean, is shrinking and modifying the heat and momentum fl uxes between the two. This freshwater will ultimately conditioned the surface wa-ters of the Labrador Sea and, in the worst case scenar-io, it will contribute to slow down the global conveyor belt circulation (Dickson et Visbeck 2002). In the best case scenario it will modify the oceanographic condi-tions on the Grand Banks (Myers 2005). Another ma-jor change is the increase in the heat transported into the Arctic Ocean by the Atlantic waters (Walczowski and Piechura 2006). Observations from the NABOS program have also shown that the temperature of North Atlantic water entering the Arctic has increased in recent years and that pulses of ocean heat are also present (Polyakov et al. 2005). All these changes are linked to the global climate system and the scarcity of observations is impeding our ability to understand the linkages.

We also critically need to better understand the connec-tions between the ecosystems and their environments in ice-covered regions to be able to minimize the im-pacts of global warming. The increase in the duration of the ice-free season will have major consequences for the marine environment. First, marine mammals relying on presence of ice to complete their annual life cycle, such as seals, belugas, narwhals, bowheads and polar bears will be directly affected by the changes in timing and duration of the ice period and indirectly by the associated ecosystem changes. Secondly, this region could become as productive as the Norwegian Sea and see the emergence of new fi sheries.

Thirdly, these waters could contribute more and more signifi cantly to the sequestration of atmospheric car-bon by the biological pump.

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ACTIVITIES

The climate mooring array along the southern shore of Lancaster Sound was successfully recovered and a real-time mooring delivery system along the northern shore was successfully deployed during summer of 2011 by DFO-BIO personnel using a CCCG icebreaker. An un-derwater cable was successfully deployed through the ice resistant shore “tube” by DND personnel and a com-munication link between an offshore mooring to shore via Iridium transmitter. The delivery system is now pro-viding real-time CTD data to southern locations via the Iridium satellite.

Unfortunately, most of the other observatories could not be recuperated in 2011 and no instruments have been moored in the summer of 2011. The only observatory that was recuperated is the one in McClure Sound. It is a world premiere: no instrument had been moored in that region before. This year was a consolidating year. Most students are in their fi rst or last year of their degree. The students in their fi rst year are still organizing their research project. The ones in their last year are writing-up. Ms. Somayeh Nahavandian (PhD student, INRS-ETE) is completing the fi rst draft of her manuscript and the seasonal evolution of the surface mixed layer in southern Beaufort Sea. Mr. Jessy Barette (MSc student, INRS-ETE) has complete his manuscript on the obser-vation and analysis of eddies in Amundsen Gulf. His manuscript will be submitted in February.

Each year since 2007, Prof. Tremblay has deployed three ice buoys south of the Byam Channel and north of the M ‘Clintock Channel at the entrance of the Vis-count Melville Sound. The Ice Mass Balance Buoy (IMB) measures sea ice thickness, internal temperature, buoy position, air temperature and pressure; the Ice Stress Buoy (ISB) measures internal sea-ice stresses, position and air temperature; the Spherical Drifter (SD) measures position, and air temperature. The purpose of this effort is to collect data to investigate sea ice melt/growth history of multi-year sea ice fl oes in the Cana-dian Arctic Archipelago (CAA), to derive geophysical mechanical strength properties of sea ice, and to use the

data to calibrate a sea ice model of the CAA to study the future sea ice conditions in the Canadian Arctic. The buoys are deployed in the fi eld by the helicopter from the Amundsen icebreaker (ArcticNet activity), and/or using a Twin Otter operated by the Polar Continental Shelf Program. The results are made public through the web on the International Arctic Buoy Program or upon request. Véronique Dansereau (MSc student, McGill) will complete shortly her work on “The calibration of a viscous plastic sea ice model”. Melissa Gervais (PhD student, McGill) is working on her thesis entitled “Arc-tic Climate Change and Precipitation”.

RESULTS

Data from the previous years up to 2011 were processed by DFO personnel and are used to estimate the volume, freshwater and heat transports through the Sound. The yearly mean transports do show a decadal variability and have been relatively low during the late 2000s. Regression analysis were performed between the transport anomalies and the NCEP/NCAR Reanalysis wind anomalies to understand the driving mechanism responsible for the transport variability of the Arctic surface water passing through the Sound. Results were presented at the international IPY, Arctic Sub-Arctic Ocean Flux (ASOF) and the Arctic Ocean Modelling Inter-comparison Program (AOMIP) meetings.

The only observatory that was recuperated in 2011 is the one in McClure Sound and the data will hopefully be analyzed in the next months. We are currently con-centrating on the analysis of the data from three moor-ings: CA04 (offshore from the Mackenzie), CA05 and CA16 from the Amundsen Gulf. Jessy Barette has writ-ten a manuscript on the distribution and origins of the eddies observed by these moorings between 2004 and 2010. His MSc thesis will be deposited before March 31.

We pursued our collaboration with Simon Prinsenberg at the Bedford Institute of Oceanography. The climate mooring work in Lancaster Sound has been stopped

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during the summer of 2011 having procured a 13yr data. The real-time mooring development is continuing along the northern coast of Lancaster Sound. Both climate and real-time datasets are used to validate and assimi-late ice-ocean mooring data into the forecast model, determine the variability of the timing and strength of biological production, narrow the range of ocean and ice parameters for offshore design, exploration and off-shore regulation codes.

The passive acoustic monitoring (PAM) part of the ocean observatory for recording the presence of marine mam-mals from their specifi c sounds and assessing ambient noise measurements in relation with global warming and ice melting was pursued in 2011-12. Recordings in 2010-11 were successful at one station in Hudson Bay (AN01). The results are reported in Prof. Barber’s Hud-son Bay project. Another time series was obtained for 2009-10 from the instrument of station AN02 that was recuperated ashore in 2011. A 1-month series for 2009 was obtained from Beaufort Sea station CA05 that was serviced in 2011. All the other mooring stations having an autonomous hydrophone were not successful and it was decided to not redeploy in 2011. The PAM series collected since 2004 now include several month time-series for CA04, CA08, AN01, AN02 and AN03, and a few week series for CA05 and BA03 (Figure 1).

DISCUSSION

Seventeen coherent structures (most of them eddies) were captured in 2007-2008 by the observatories and the ship-based sampling. Since only two McLane Moored Profi lers were moored, we can assume that a lot more of these eddies are drifting around the Amund-sen Gulf (and Southern Beaufort Sea). These eddies are lens-shaped and drift at approximately 3 km day-1. They are believed to last many months (Timmerman et al. 2008) and they can carry whole ecosystems with them.

In 2011-12 signal processing methods for systematic and uniform hierarchical analyses of the data series in the different IRIS regions are being developed and exploited. Analyses focused in 2011 to the extraction of the annual cycle of ambient noise and soundscape characterization from CA04 and CA08 series. Similar processing is planned for the 3-y time-series of AN03 in 2012.

Change of the pristine underwater soundscape in re-sponse to increasing exposure of the ocean surface to natural sound sources, such as wind and waves, and eventually to new anthropogenic sources arising with the acceleration of the economic development, espe-cially shipping and oil and gas activities, is one of these elusive impacts of global warming on marine ecosys-tems. The underwater sounds capes of the Arctic are largely unknown. Short-term, dedicated and partial acoustic studies have indeed been undertaken in the Arctic, but a thorough characterisation of soundscapes over a complete annual cycle in relation with the ice cover has is still missing. This fi rst work contributes to fi ll this knowledge gap by the analysis of a 13-month acoustic dataset recorded from a moored autonomous hydrophone in Beaufort Sea, Canada, in 2005-2006. An ambient noise extraction algorithm was developed to obtain the annual time-series of the natural soundscape over a 4-kHz bandwidth, exclusive of transient sounds due to biological or physical sources. Under-ice ambi-ent noise spectra clearly differed from open-water ones, as evidenced from unsupervised classifi cation analysis. Sound levels in open water conditions increase by 10-

Figure 1. Broadband passive acoustics time-series recorded by the observatory since 2004. Black = [0-4 kHz] bandwidth. Red = [0-16 kHz] bandwidth. Bold = preliminary analyses. Dotted line = low duty cycle.

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30 dB depending on frequency. The effect of the grad-ual lengthening of the open-water season in response to global warming is estimated from the observed seasonal change. The effects of such a large increase of ambient noise in the frequency bandwidth used by fi sh and ma-rine mammal for their communication and sensing of the environment require specifi c research.

CONCLUSION

We have reached a major turning point in this project. We have now obtained our fi rst medium range (six years) validated physical and sediment traps data time series and over 20 manuscripts using observatory data were published in the past three years. A synthesis of all the currently available physical, biological and chemi-cal data has been completed (Forest et al. 2011) in the form of a carbon fl ux, inverse model. Next year we will concentrate on the interpretation of the Passive Acous-tic Monitoring data and on publishing the numerous physical oceanography studies on currents, pulses and eddies. Lancaster Sound Climate mooring has been re-moved after providing 13 years of data which may be long enough to see the decadal cycle and possible trends due to global warming. Work is continuing to develop a real-time mooring data delivery system. Datasets from both projects will contribute to provide real-time ice-ocean mooring data for increasing the accuracy of forecast models for the safety of developments, trans-portation and Search and rescue work and provide the temporal and spatial variability of the biological pro-duction.

We should consider splitting the long-term observa-tories project into a technical sub-project (sea-going technicians, moorings, CTD operations and data quality control) and a scientifi c sub-project (students, post-docs and scientifi c analysis). We now have the bare minimum long-term dataset needed to undertake and publish more scientifi c analysis. However, theses time series, except for the Lancaster Sound one, are still not long enough to look at decadal and longer cycles.

ACKNOWLEDGEMENTS

We would like to thank the offi cers and crew of the CCGS Amundsen for their help and dedication to the success of ArcticNet. We also want to thank all the Québec-Océan technicians (Luc Michaud, Pascal Mas-sot, Sylvain Blondeau, Steve Levesque, Jean Ouellet, Frédéric St-Germain, Alain Létourneau and many others over he years) that are working hard all year round and especially aboard the Amundsen where a 18 h working day is frequent. We also want to thank all the rosette op-erators, graduate students and research assistant (Marie-Emmanuelle Rail, Pascal Guillot, Dominique Boisvert, Claude Bélanger, Dominique Robert and Jessy Barette) who acquired, quality-controlled, processed and inter-preted the rosette and mooring data over the years. This work was also funded by NSERC Discovery grants to each NIs and by Government of Quebec infrastructure (to Québec-Océan) and team grants.

REFERENCES

Dickson R.W., Visbeck, M.H. 2002. Journal of Physical Oceanography 32: 687–701.

Forest A., Tremblay, J.E., Gratton, Y., Martin, J. Gag-non, J., Darnis, G., Sampei, M., Fortier, L., Ardyma, M., Gosselin, M., Hattori, H., Nguyen, D., Maranger, R., Vaqué, D., Marassé, C., Pedros-Alio, C., Sallon, A. Michel, C., Kellogg, C., Deming, J., Shadwick, E., Thomas, H. Link, H. Archambault, P., Piepenburg. D. 2011. Biogenic carbon fl ows through the planktonic food web of the Amundsen Gulf (Arctic Ocean): A synthesis of fi eld measurements and inverse modeling analyses. Progress in Oceanography, 91, 410-436.

Maslanik, J., Stroeve, J., Fowler, C., Emery, W. 2011. Distribution and trends in Arctic sea ice through spring 2011. Geophysical Research Letters, doi:10.1029/2011GL047735.

Melling, H. 2000. Exchange of freshwater through the shallow straits of the North American Arctic. In

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Lewis, E.L. et al. (Eds.). The Freshwater Budget of the Arctic Ocean, Kluwer Academic, 479–502.

Myers, P.G. 2005, Impact of freshwater from the Ca-nadian Arctic Archipelago on Labrador Sea Water formation Geophysical Research Letters 32 L06605, doi:10.1029/2004GL022082.

Polyakov, I., Beszczynska, A., Carmack, E., Dmitren-ko, I., Fahrbach, E., Frolov, I., Gerdes, R., Hansen, E., Hol- fort, J., Ivanov, V., Johnson, M., Karcher, M., Kauker, F., Morison, J., Orvik, K., Schauer, U., Sim-mons, H., Skagseth, Sokolov, V., Steell, M., Timokhov, L., Walsh, D., Walsh, J. 2005. One more step toward a warmer Arctic. Geophysical Research Letters 32, L17605, doi:10.1029/2005GL023740.

Timmerman, M.-L., Toole, J., Proshutinsky, A., Krish-fi eld, R., Plueddemann, A. 2008. Eddies in the Canada Basin, Arctic Ocean, observed Ice-tethered profi lers. Journal of Physical Oceanography 38:133-145.

2011-12 PUBLICATIONS

All ArcticNet refereed publications are available on the ASTIS website (http://www.aina.ucalgary.ca/arcticnet/).

Forest, A., J.-É. Tremblay, Y. Gratton, J. Martin, J. Gagnon, G. Darnis, M. Sampei, L. Fortier, M. Ardyna, M. Gosselin, H. Hattori, D. Nguyen, R. Maranger,D. Vaquié, C. Marrasé, C. Pedros-Alio, A. Sallon, C. Michel, C. Kellog, J. Deming, E. Shadwick, H. Thomas, H. Link, P. Archambault, D. Piepenberg,, 2011, Biogen-ic carbon fl ow pathways in the planktonic food web of the Amundsen Gulf: a synthesis of fi eld measurements and inverse modeling analysis. Progress in Oceanogra-phy, Progress in Oceanography., 410-436.

Gratton, Y., D. Bourgault, P.S. Galbraith, L. Prieur, V. Tsarev et al., 2012, Physical Oceanography during CFL., In D. Barber and J. Deming eds, The Circumpo-lar Flaw Lead Study., 250 p.

Kinda, B., Simard, Y., Gervaise, C. et Fortier, L., 2011, Ambiance sonore de l’Arctique: extraction et caractérisation du cycle annuel en Mer de Beau-fort, Québec-Océan, AGA-2011. Québec. 17-18 nov, 1.

Rail, M.-E. and Gratton, Y., 2011, Distribution of tem-perature and salinity in the Canadian Arctic Archipel-ago during the 2007 and 2008 ARCTICNET sampling expeditions., INSR-ETE, Report R0001243, 65 p.

Rail, M.-E. and Gratton, Y., 2011, Distribution of tem-perature and salinity in the Canadian Arctic Archipel-ago during the 2009 ARCTICNET sampling expedi-tion., INRS-ETE, Report R1248, 69 p.

Sampei, M., H. Sasaki, R. Makabe, A. Forest, H.Hattopri, J.-É. Tremblay, Y. Gratton, M. Fukuchi and L. Fortier., 2011, Production and retention of biogenic-matter in the southeast Beaufort Sea during 2003-2004 insights from annual vertical particle fl uxes of organic carbon and biogenic silica., Polar Biology, 502-511.

project leader - | arcticnetarctic ocean is the world largest source of freshwater. the canadian...

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