Publication Date:
2019-07-17
Description:
Carbon (δ13C) and nitrogen (δ15N) stable isotope values of deep-sea benthic copepods,
nematodes, and sediments were determined along a latitudinal transect covering bathyal and abyssal
depths in the Southern Ocean and the Weddell Sea (49° S to 70° S). This is the first time geographically
interpretable stable isotope data including δ15N are presented for deep-sea meiofauna. In agreement
with previous findings on isotopic patterns of sea-surface organic matter, the deep-sea meiofauna
δ13C and δ15N values gradually declined with latitude. The southernmost Lazarev Sea station was an
exception to this trend. A long-lasting sea-ice cover and a primary production dominated by 13Cenriched
ice algae lead to isotopic signals that were heavier than expected for this latitude. The
greatest 13C depletions were found in the communities of Maud Rise. Compared to the Weddell Sea
and the Lazarev Sea, this seamount region is first free of ice and thus earlier and longer under influence
of the isotopically lighter water column diatoms. The prevailing oceanographic conditions additionally
favor an enhanced transportation velocity of surface POM to the seafloor at Maud Rise. Generally small
offsets between calculated surface δ13CPOM values and the deep-sea organisms suggested a strong
bentho-pelagic coupling. Benthic copepods and nematodes seem to be primary or secondary
consumers of planktonic detritus. Meiofauna individual numbers and community composition did not
differ distinctly along the transect spanning a distance of 2400 km and covering a range of 3400 m
water depth. This observation can be attributed to the overall low and patchy organic C fluxes to the
seafloor
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev
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