ocean optics meets taxonomy: case study in southern ......ocean optics meets taxonomy: case study in...
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Ocean optics meets taxonomy: case study in Southern Adriatic Pit1 2 3 1 1 1 4 5 5 1Bošnjak I. , Petrić I , Cetinić I. , Bosak S. , Mejdandžić M. , Kružić P. , Mihanović H. , Miloslavić M. , Lučić D. , Ljubešić Z.
1Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia; 2Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia;
3 NASA Goddard Space Flight Center/USRA, Ocean Ecology Laboratory, Greenbelt, MD, United States; 4Physical Oceanography Laboratory, Institute of Oceanography and Fisheries, Split, Croatia;
5Institute for Marine and Coastal Research, University of Dubrovnik, Dubrovnik, Croatia
The immense diversity of oceanic plankton and its distribution is hard to access with a single method only. Discrete samples, analysed through imaging, pigments or molecular methods, offer a great view of the composition, but offer only a limited resolution of plankton over space and time. Optical tools, deployed on in situ and from remote sensing platforms, allow high spatial and temporal view, but tell very little about plankton composition. However, combination of these techniques offers an all-inclusive view of plankton diversity in the ocean.
WHERE?BIOTA [Bio-tracing Adriatic water masses] Winter Cruise was conducted in oligotrophic waters of the Southern Adriatic Pit (Figure 1.)
WHYAim: specific winter circulation &
distribution of phytoplankton
Two major transects: 1. Dubrovnik to 1000 m isobath (in direction 210º)2. 1000 m isobath to Lastovo
Influence of: - Levantine Intermediate Water (LIW) - East Adriatic Current (EAC)
HOWPhysicsCTD casts - temperature, salinity, oxygen, light (PAR) Optical analysis (biology): CTD casts - chlorophyll fluorescence, particulate backscattering and beam attenuation derived data- particulate organic and phytoplankton carbon, optical indices (optical community index and backscattering ratio)Phytoplankton and zooplankton abundances: microscopy, flow cytometry and molecular identification methods
CONCLUSIONEncountered distribution of the plankton in the water column reflects an intricate play of the water masses in the studied area. Overall, our results suggest that different portions of plankton community, here separated by their size, respond to different environmental cues in this oligotrophic oceanic ecosystem.
1.2.
J. Godrijan
ACKNOWLEDGMENTSThis work was fully supported by Croatian Science Foundation under the project 6433.
A New Age of Discovery for Aquatic MicroeukaryotesEMBL Heidelberg, Germany
26 January - 29 January 2016
Figure 1. Map of investigated area with satelite photographs taken February 18 2015., a week before the BIOTA cruise showing Chl a concentrations and two investigated transects with stations as red dots.
OVERVIEW
WHENth rdFebruary 28 - March 3 2015
Combination of techniques!
1% PAR
Station P100 (28/2/2015)(»control station» for optical parameters - no surprises there)
Physics Biology Biology
Figure 2. Vertical profiles at P100 station of a - temperature, salinity and oxygen concentration; b - Chl a values from CTD cast and derived particulate organic carbon and phytoplankton carbon; c - optical community index and backscattering ratio; d - phytoplankton groups
Optics
a b c d
Dominance of DIATOMS
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0
0 4000 8000 12000 16000diatoms (cells L-1)
0 4000 8000 12000 16000coccolithophorids (cells L-1)
P100diatoms
cocco
Average zooplankton densities showed graduate decrease with dep th . Unexpec ted ly, h igh numbers of microzooplankton were recorded at all stations, with average densities greater than 10
-3000 ind. m in the upper 300 m of the water column., while lowest abundances were recorded at P600 station.
1% PAR
1% PAR
P600 (1/3/2015)Picophytoplankton (picoeukaryotes) and zooplankton
Physics Biology
ھ 4000 8000 12000 16000Abundance (cells L-1)
500
450
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0
P600
picoeukaryotes
Prochlorococcus
Synechococcus
280 m
200 m
Figure 10. Light micrographs of Picochlorum sp. clone isolated at station P600. Vegetative cells and cells in autosporulation. White arrows indicate cell division and mother cell wall; black arrows indicate large lobbed chloroplast.
Figure 9. Vertical profile of picophytoplankton groups. yellow arrow: layer with min oxygen & chl values, green arrow: picoeukaryote abundance maximum.
Figure 8. Vertical profiles at P600 station of a - temperature, salinity and oxygen concentration; b - Chl a values from CTD cast and derived particulate organic carbon and phytoplankton carbon; c - optical community index and backscattering ratio; yellow arrow: layer with minimal oxygen & Chl a values, green arrow: picoeukaryote abundance maximum
Optics
Figure 11. Microzooplankton abundance at P600 station -3(no. ind.m )
5µm 10µm
5µm
a b c
Figure 4. Some of the coccolithophore species recorded at P150A station. a - Emiliania huxleyi; b - Umbilicosphaera sibogae; c - Helicosphaera HOL dalmaticus type d - Calcidiscus leptoporus. Photographs by J. Godrijan.
1% PAR
P150A (3/3/2015)picophytoplankton (cyanobacteria) and coccolithophores
Physics Biology Biology
0 4000 8000 12000 16000Abundance (cells L-1)
140
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0
P150 A
picoeukaryotes
Prochlorococcus
Synechococcus
0 10000 20000 30000Abundance (cells L-1)
140
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P150A
diatoms
dino
cocco
crypto
chloro
Figure 3. Vertical profiles at P150A station of a - temperature, salinity and oxygen concentration; b - Chl a values from CTD cast and derived particulate organic carbon and phytoplankton carbon; c - optical community index and backscattering ratio; d - phytoplankton groups
Optics
a
a b
c d
b c
a - 20m
b - 80m
c - 140m
d
Dominance of COCCOLITHOPHORES
160
120
80
40
0
0 4000 8000 12000 16000 20000diatoms (cells L-1)
0 4000 8000 12000 16000 20000coccolithophorids cells L-1
P150A
diatoms
cocco
Figure 5. Vertical profile of nanophytoplankton groups. Figure 6. Vertical profile of picophytoplankton groups.
Figure 7. ITS-based neighbour-joining phylogenetic trees showing the inferred evo lu t i ona ry re la t i onsh ips among Prochlorococcus sequences retrieved from the Adriatic sea (station P150A) collected at depths 20 m (a), 80 m (b) and 140 m (c) in r e l a t i on t o p rev i ous l y sequenced Prochlorococcus. Phylogenetic clade affiliation is indicated at right: HL—High light adapted, LL—Low light adapted, as determined by physiological studies of isolates.