JPR Advance Access originally published online on September 30, 2004
Journal of Plankton Research 2005 27(1):19-26; doi:10.1093/plankt/fbh144
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Journal of Plankton Research Vol. 27 No. 1 © Oxford University Press 2004; all rights reserved
State-dependent vertical distribution of the carnivore copepod Pareuchaeta norvegica
University of Oslo, Department of Biology, Po Box 1066, Blindern, 0316 Oslo, Norway
* Corresponding Author: stein.kaartvedt{at}bio.uio.no
Received July 8, 2004; accepted in principle August 11, 2004; accepted for publication September 14, 2004; published online September 30, 2004
We explored the impact of body condition on vertical distribution of the carnivore copepod Pareuchaeta norvegica. Individuals sampled in the upper part of the water column had lower dry weight and slightly shorter prosome than individuals sampled deeper. Non-ovigerous females occurred higher in the water column than ovigerous females. Our results suggest that ovigerous females and individuals with large energy reserves to a large extent prioritize predator avoidance in deep water versus feeding in the upper part of the water column compared to non-ovigerous females and individuals with low energy reserves. Adult females collected closest to the surface were less pigmented than those found deeper. This, however, proved to be a quickly adjustable trait depending on prevailing light conditions.