Zooplankton of the Ocean: patterns of diversity and productivity

Ksenia Kosobokova P.P. Shirshov Institute of Oceanology Russian Academy of Sciences, Moscow,

in collaboration with H-J. Hirche and R.R. Hopcroft The Arctic Mediterranean Sea Bering Strait =

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Water exchange with the North Atlantic via deep (2000m) Strait

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Atlantic water: 200-900 m depth, positive temperature, salinity 34-34.9

Arctic Bottom water: below 1000 m, negative temperature, higher salinity 34.93-34.99 First zooplankton collections were obtained during the “Fram” drift in 1893-1896

G.O. Sars, 1900. The Norwegian Expedition 1893- 1896. Scientific results. F. Nansen (ed.). V.1, No. 5. 141 pp.

The first list of AO crustacean zooplankton with description of new species Russian ”North Pole” (NP1) 1937-1938 9 months of drift, zooplankton collected at 14 locations down to 1500m using a hand winch ColoredMost linesdrifting - routes ice stations of the started drifting their stations drift in NP the-2 – NP-Canadian37, 1950 Basin-1978,, where green the linestrongest - the and ice thickestisland T ice-3 platforms were chosen to build the ice camps, and they drifted mostly within this basin

Canadian Basin Period of sporadic semi-quantitative sampling, For a long Different sampling methods and gears,time almost no data Different sampling layers (predominantlyexisted surface from layers 0-100, 0-500 m),the Eurasian Basin Difficult to drawEurasian any inter-regional and quantitativeBasin comparison… New Age since 1980-es: «Breaking the ice…»

“Academician Fedorov”, Russia

Icebreaker “Polarstern”, Germany

USCGC “Healy”, USA Modern gears and standard sampling methods

Multinet: Bongo net: ROV: Quantitative vertical sampling Oblique or In situ (5 to 9 layers) vertical sampling observations and collection of fragile organisms

Scuba divers „Polarstern“ zooplankton sampling programs in the central Arctic, 1993-2015 Stations in 1993-1998, 2007, 2011 were located along sections crossing the core of the Atlantic Boundary current

Siberia Siberia

Greenland Zooplankton station locations, 1993-

2015 Stratified sampling of the water column with MN at 202 locations; 153 sts. at bottom depth >1000 m Expeditions: 1) RV “Polarstern”: ARK IX/4, 1993 ARK XI/1, 1995 ARK XII, 1996 ARK XIII, 1997 ARK XIV, 1998 ARK XXII/2, 2007 ARK XXVI/3, 2011 PS94, 2015

2) USCGC “Healy”, 2005

3) “North Pole” stations: NP-22: 1975-76 NP-23: 1976-77 Research objectives: • Study of the zooplankton diversity throughout the entire depth range to produce detailed inventory and to document any ongoing changes in the species composition;

• Biomass and abundance assessment: how much and where? • Study of regional biomass variability: what factors shape it? • Polar zooplankton ecology: - study of life strategies and reproductive biology of epi- and mesopelagic zooplankton to better understand their life traits; - study of lipid contebt and starvation potential of lipid accumulating key copepod species; - organic carbon content analysis, C/N ratio, stable isotopes ratio, dry mass, and lipid composition in dominant plankton taxa Species composition and diversity

Sub-project of the CoML ‘Arctic Ocean Diversity’ (ArcOD) program, 2007-2010

• Detailed inventory of the zooplankton fauna of the deep Arctic Ocean • Comparison of the zooplankton composition in the four major deep basins of the Arctic Ocean separated by underwater ridges (Nansen, Amundsen, Makarov, Canada basins) • Analysis of patterns of zooplankton diversity vs. water depth

Kosobokova et al., 1998; Kosobokova & Hirche, 2000; Markhaseva & Kosobokova, 1998, 2001; Stepanjants & Kosobokova, 2006; Kosobokova & Hopcroft, 2010, Kosobokova et al., 2011; Andronov & Kosobokova, 2011; Zasko & Kosobokova 2014 Zooplankton diversity and taxonomical composition No. of Taxon A total of 175 species metazoan species • Arthropoda (Crustacea): 122 Copepoda 91 Ostracoda 5 Hyperiidea 6 Other taxa, Gammarideа 11 12% Mysidacea 4 Euphausiacea 4 Cnidaria 23 Decapoda 1 • Cnidaria: 25 15% 25 Scyphozoa (Scyphomedusae) 3 Hydrozoa (Hydromedusae) 15 Siphonophora 7 30 91 • Ctenophora 7 • Gastropoda (Pteropoda) 2 Other • Annelida (Polychaeta) 5 Crustacea • Nemertea 1 18% Copepoda, • Chordata (Larvacea) 4 54% • Chaetognatha 4 Kosobokova et al. 2011, Kosobokova 2012 Biogeography of AO zooplankton: 85% resident species (locally reproducing), and 15% expatriates (not reproducing)

- High rank of endemism due to isolation of the Arctic Ocean deep basin; - Large portion of species shared with North Atlantic due to permanent advection of fauna with Atlantic water and similar conditions at depths; - Small portion of species shared with the Pacific Benthopelagic due to isolation by the shallow Bering Strait and wide shallow Chukchi Sea shelf

Kosobokova 2012 Oceanic expatriates: Advection and distribution of Atlantic vs. Pacific species

Legend 0 - 862 Neocalanus crystatus >862 - 3002 Pacific copepods Ncristatus Atlantic copepod Metridia pacifica >3002 - 5848 (ind m-2) Mpacifica Calanus finmarchicus Eucalanus bungei >5848 - 12348 Ebungii (ind m-2) >12348 - 41680 Vertical ranges of species

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A A A M M D E

H S H L P S P P S P L L S L

G C U T O 2400 0-25 2600Arctic 25-50 Water 50-100

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2800 , 100-200Canada Basin, copepods

h 3000t Atlantic 200-300Eurasian Basin, copepods p 300-500

e Water 500-750CB, all taxa

D Arctic 750-1000EB, all taxa Bottom 1000-2000 Water 2000-3000 Deep-water residents: is not a barrier for the deep-water fauna

Almost all deep-water species occur on both sides of the Lomonosov Ridge = There is an effective exchange of plankton fauna over the underwater ridges Quantitative composition: copepods dominate biomass

82ºN 86ºN Eurasian Basin

72-76ºN 86ºN

Canadian Basin % of % overall biomass

Depth, m

Eurasian Basin Canadian Basin Region Mean ± SD Mean ± SD Share of Continental slope 88.0 ± 11.4 74.4 ± 2.2 copepods Basins south of ± ± 82ºN 80.9 5.0 75.1 4.6 Basins north of ± ± 85ºN 91.4 2.8 93.4 5.4 Key copepod species Biomass (%) Body Eurasian Species length, Basin Eurasian Basin Canadian mm <82°N >85°N Basin Calanus glacialis 5.0 19.6 14.8 9.9 C. hyperboreus 8.0 21.5 46.5 29.2 C. finmarchicus 3.2 11.2 0.5 0 Metridia longa 4.5 12.1 4.4 7.4 Total 64.4 66.2 46.5

м

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C. finmarchicus C. glacialis Metridia longa C. hyperboreus А Б В Distribution patterns of the three Calanus species in AO

C. gla

C.fin C. hyp Calanus finmarchicus

Spatial distribution of CF is closely related to circulation of Atlantic water in Eurasian Basin

40% of overall biomass S. Østerhus and B. Rudels

Eurasian Basin Eurasian Basin Canadian Species <82°N >85°N Basin C. finmarchicus 11.2 0.5 0 Overall zooplankton biomass, g DW m-2, entire water column (0m – bottom)

Typical biomass values within the range: from 2 to 6 g DW m-2, with maximum up to 12-24 g DW m-2 (maximum biomass ever found in the Arctic Ocean)

Historical values: Hopkins, 1969a, b g DW m-2 AMUNDSEN BASIN 0.2-0.4 CANADA BASIN 0.2-0.4 Kosobokova, 1982 MAKAROV BASIN 1.0-3.0

Kosobokova & Hirche, 2009 Major features/gradients

Region No. of Biomass, stations g DW m-2 mean ± SD EB, all stations 44 6.2 ± 4.1 EB, south of 81ºN 38 6.9 ± 4.1 Basins north of 82ºN 8 2.7 ± 0.6

1. A belt of elevated biomass along the Eurasian slope 2. A decrease of biomass within this belt from the West to the East 3. South to north gradient: a decrease of overall biomass from the slope area to the central basins; Highest biomass is found within or close to the core of the Atlantic Boundary Current Kosobokova & Hirche, 2009 Local and advected carbon supply “Carbon Belt” around Vertical biomass distribution Eurasian Basin perimeter

Zooplankton overall biomass g DW m-2 Benthos

North of 85°N inflow

Bluhm et al. 2011 Zooplankton advection through the Pacific and Atlantic gateways

Bering Strait: Concentration of plankton advected 0.8 mln T C org through the Bering Strait is 3 times higher compared to Atlantic gateways; But The advective supply of plankton through the Atlantic gateways is 2–3 times higher because of 10 fold difference in amount of advected water;

Allochthonous carbon delivered through the Atl gateways is distributed all along the Eurasian slope E basins southern periphery, 2.57 mln T C org On Pacific side it is restricted to the Chukchi shelf only Wassmann et al. 2015 Summary: • Our knowledge on the Arctic Ocean zooplankton diversity seriously improved during two last decades; existing information can be used as a baseline for monitoring the ongoing changes in the AO plankton communities; • The Arctic Ocean hosts two major zooplankton communities: 1) An autochthonous low productive community found in the Canada Basin and in its purest form in the inner northern basins; 2) An allochthonous community consisting of advected species. It has its biomass maximum in the Atlantic boundary current; • A strong regional variability of biomass distribution in AO is structured by the circulation pattern, and the Atlantic inflow is the most important structuring feature Thank you for attention

• My deep gratitude to my AWI colleagues Dr. E. Rachor, Dr. H-J. Hirche, Dr. U. Schauer, Dr. E.-M. Noethig, Dr. H.-M. Kassens, T. Scherzinger, B. Strohscher, U. Holtz, Dr. K. Barz • Dr. H. Hanssen (IPO): • Dr. S. Timofeev (MMBI, Russia) • Dr. R. Hopcroft (University of Fairbanks, Alaska, USA) • Dr. Elena Markhaseva (ZIN RAS, Russia) • for the longstanding fruitful cooperation in the Arctic Acknowledgements:

• This work was supported by visiting scientist grants of the Alfred Wegener Institute, NOAA office of Ocean Exploration and Arctic Research Office, Russian Foundation for Basic Research, grant No. 06-05-65187. • This research represents a contribution to the Arctic Ocean Biodiversity (ArcOD) project of the Census of Marine Life.