Meroplanktonic larvae in the marine food web - a combination of grazing experiments and stable isotope analyses at Helgoland Roads, North Sea


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Eike.Gentsch [ at ] awi.de

Abstract

Knowledge about the feeding behavior and the importance of meroplanktonic larvae in the marine food web is rare, even though these larvae are, at times, even more abundant than holoplanktonic organisms such as copepods. The aim of this study was to better understand the role of the meroplanktonic larvae as potential grazers in the food web of the North Sea at Helgoland Roads. Here, we present results from a combination of feeding experiments and δ15N and δ13C stable isotope analyses of abundant meroplanktonic larvae, i.e. Liocarcinus sp. and Lanice conchilega. Experiments and stable isotope sampling were conducted weekly from late April to August 2006. In the feeding experiments, the larvae were incubated for 7h in natural, 70µm pre-screened seawater at ambient water temperature. Feeding rates were determined by measuring pigment concentrations in the incubation-water before and after the incubation. Stable isotope signatures were determined in abundant zooplankton groups and in the seston to monitor the long term feeding history. The experiments show that larvae fed upon phytoplankton at various rates. Also the results from stable isotope analysis point to feeding on lower trophic levels. In general, the stable isotope signatures in the larvae were approximately one trophic level above the signatures found in the seston throughout the time series. The trophic position of larvae of a single species did not change significantly with growth in summer. Differences in trophic levels were only found between taxa. Meroplanktonic larvae can play a major role as grazers in marine food webs.



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Conference (Poster)
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Not peer-reviewed
Publication Status
Published
Event Details
4th ICES International Zooplankton Production Symposium, May 28 - June 1 2007, Hiroshima, Japan..
Eprint ID
17244
Cite as
Gentsch, E. , Wiltshire, K. H. and Niehoff, B. (2007): Meroplanktonic larvae in the marine food web - a combination of grazing experiments and stable isotope analyses at Helgoland Roads, North Sea , 4th ICES International Zooplankton Production Symposium, May 28 - June 1 2007, Hiroshima, Japan. .


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