Publikationsdatum:
2019-07-17
Beschreibung:
Carbon (d13C) and nitrogen (d15N) 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–70�S). This is the first time geographical patterns in stable
isotope composition including d15N are reported for deep-sea meiofauna. In agreement with previous
findings on isotopic patterns of sea-surface organic matter, the deep-sea meiofauna d13C values gradually
declined with latitude. In the nematodes, d15N values were depleting southwards and followed the
known gradients of increasing nitrate concentrations with decreasing d15N values available to primary
producers in the surface waters. Differences in productivity, water depth, and degradation state of the
organic matter at the seafloor along the transect did not influence the southwards declining trend
observed in the stable isotope values of the deep-sea meiofauna. The most depleted 13C values were
detected in the communities of Maud Rise. The southernmost Lazarev Sea station was an expected exception
to this trend: its long-lasting sea-ice cover and a primary production dominated by 13C-enriched ice
algae may have lead to the heavier isotopic signatures that were encountered in the organisms and sediments
at 70�S. It is suggested that the bulk of benthic meiofauna mainly feeds on degraded organic matter,
a food source that is continuously available throughout the year, because only small differences of
sediment d13C and the values for meiofauna were detected. The isotopic composition of consumers such
as copepods and nematodes are a combination of geographical conditions and the organisms’ position in
the food web. Hence, the comparison of stable isotope values of deep-sea meiofauna over a wide geographical
range yields basic information for detailed follow-up studies on Antarctic meiofauna foodwebs
Repository-Name:
EPIC Alfred Wegener Institut
Materialart:
Article
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