Regional patterns of nematode assemblages in the Arctic deep seas |
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Authors: | Gustavo Fonseca Thomas Soltwedel |
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Institution: | (1) Deep-Sea Research Group, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany |
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Abstract: | Surface primary productivity and carbon flux in the Arctic Seas are higher along the warm Spitsbergen Water Current than along
the ice-infested East Greenland Current. These contrasting oceanographic conditions are reflected in the deep-sea environment
and may shape nematode assemblages. However, the paucity of samples in the Arctic deep seas precludes any regional scale assessment.
In the present study, nematode assemblages were investigated in relation to a range of environmental variables along the 2,000 m
isobath between latitudes 72°N and 79°N for both East and Western margins of the northern North Atlantic. Results showed that
both margins had distinct environmental characteristics, with respect to chloroplastic pigments, sediment water content, sediment-bound
organic matter, phospholipids and particulate proteins. Nematode assemblages varied according to these environmental changes.
Along the more oligotrophic western margin, chloroplastic pigments increased towards the North, while the other environmental
variables, nematode abundances and species richness decreased. In contrast, along the eastern margin, we observed higher quantities
of organic matter and particulate protein, which supported higher abundance and species richness. Nematode assemblages along
both margins varied according to food availability with species composition more variable in areas with lower amounts. Seventy
percent of the species occurred in both margins indicating a low turnover of species. The present results support the hypothesis
of a positive latitudinal gradient across the North Atlantic and further suggest that contemporary climate and recent ecological
processes may predict nematode diversity patterns at larger scales. |
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