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| Titel |
Structural and functional responses of harpacticoid copepods to anoxia in the Northern Adriatic: an experimental approach |
| VerfasserIn |
M. Troch, M. Roelofs, B. Riedel, M. Grego |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 6 ; Nr. 10, no. 6 (2013-06-26), S.4259-4272 |
| Datensatznummer |
250018311
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| Publikation (Nr.) |
 copernicus.org/bg-10-4259-2013.pdf |
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| Zusammenfassung |
Combined in situ and laboratory studies were conducted to document the effects of
anoxia on the structure and functioning of meiobenthic communities, with
special focus on harpacticoid copepods. In a first step, anoxia was created
artificially by means of an underwater chamber at 24 m depth in the Northern
Adriatic, Gulf of Trieste (Mediterranean). Nematodes were found as the most
abundant taxon, followed by harpacticoid copepods. While nematode densities
were not affected by treatment (anoxia/normoxia) or sediment depth, these
factors had a significant impact on copepod abundances. Harpacticoid copepod
family diversity, in contrast, was not affected by anoxic conditions, only
by depth. Ectinosomatidae and Cletodidae were most abundant in both normoxic
and anoxic samples.
The functional response of harpacticoid copepods to anoxia was studied in a
laboratory tracer experiment by adding 13C pre-labelled diatoms to
sediment cores in order to test (1) if there is a difference in food uptake
by copepods under normoxic and anoxic conditions and (2) whether initial
(normoxia) feeding of harpacticoid copepods on diatoms results in a better
survival of copepods in subsequent anoxic conditions. Independent of the
addition of diatoms, there was a higher survival rate in normoxia than
anoxia. The supply of additional food did not result in a higher survival
rate of copepods in anoxia, which might be explained by the presence of a
nutritionally better food source and/or a lack of starvation before adding
the diatoms. However, there was a reduced grazing pressure by copepods on
diatoms in anoxic conditions. This resulted in a modified fatty acid
composition of the sediment. We concluded that anoxia not only impacts the
survival of consumers (direct effect) but also of primary producers
(indirect effect), with important implications for the recovery phase. |
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