Bathymetric patterns in standing stock and diversity of deep-sea nematodes at the long-term ecological research observatory HAUSGARTEN (Fram Strait)


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Thomas.Soltwedel [ at ] awi.de

Abstract

Bathymetric patterns in standing stocks and diversity are a major topic of investigation in deep-sea biology. From the literature, responses of metazoanmeiofauna and nematodes to bathymetric gradients arewell studied, with a general decrease in biomass and abundance with increasing water depth, while bathymetric diversity gradients often, although it is not a rule, show a unimodal pattern. Spatial distribution patterns of nematode communities along bathymetric gradients are coupled with surface-water processes and interacting physical and biological factors within the benthic system. We studied the nematode communities at the Long-TermEcological Research (LTER) observatory HAUSGARTEN, located in the FramStrait at theMarginal Ice Zone, with respect to their standing stocks as well as structural and functional diversity.We evaluated whether nematode density, biomass and diversity indices, such asH0, Hinf, EG(50), Θ−1, are linkedwith environmental conditions along a bathymetric transect spanning from 1200mto 5500mwater depth. Nematode abundance, biomass and diversity, as well as food availability from phytodetritus sedimentation (indicated by chloroplastic pigments in the sediments), were higher at the stations located at upper bathyal depths (1200–2000 m) and tended to decrease with increasing water depth. A faunal shift was found below 3500 m water depth, where genus composition and trophic structure changed significantly and structural diversity indices markedly decreased. A strong dominance of very fewgenera and its high turnover particularly at the abyssal stations (4000–5500 m) suggests that environmental conditions were rather unfavorable for most genera. Despite the high concentrations of sediment-bound chloroplastic pigments and elevated standing stocks found at the deepest station (5500 m), nematode genus diversity remained the lowest compared to all other stations. This study provides a further insight into the knowledge of deep-sea nematodes, their diversity patterns and a deeper understanding of the environmental factors shaping nematodes communities at bathyal and abyssal depths.



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Article
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Scopus/ISI peer-reviewed
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Published
Eprint ID
40717
DOI 10.1016/j.jmarsys.2017.02.003

Cite as
Grzelak, K. , Kotwicki, L. , Hasemann, C. and Soltwedel, T. (2017): Bathymetric patterns in standing stock and diversity of deep-sea nematodes at the long-term ecological research observatory HAUSGARTEN (Fram Strait) , Journal of Marine Systems, 172 , pp. 160-177 . doi: 10.1016/j.jmarsys.2017.02.003


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