Abstract

Mortality rates of the copepods Calanus hyperboreus, C. glacialis, C. finmarchicus, Pseudocalanus sp. and Oithona similis were investigated during June 2001 in Disko Bay, western Greenland. These 5 species dominated the zooplankton community in the upper 75 m, contributing 89 % of the total copepod biomass. Instantaneous mortality rates of copepodites of all 5 species and nauplii of Pseudocalanus sp. and O. similis were calculated using vertical life tables on abundances and published information on stage duration times. Compared with those covering a range of boreal habitats, the mortality rates were higher, with highest rates occurring in C. finmarchicus and C. glacialis copepodite stages I to III and Pseudocalanus spp. stage III (maximum = 0.18 d(-1)). Mortality rates remained lower in all stages of O. similis, When superimposing mortality rates for all species and stages on copepod size a significant peak at 1.3 mm prosome length was evident. This peak fitted a prey size dependent functional response of predation and the high mortality rates were, therefore, most probably attributable to size-specific predation.

Keywords

arctic copepods; mortality rates; Calanus; Pseudocalanus; Oithona

Published in

Marine Ecology Progress Series
2008, volume: 359, pages: 151-160
Publisher: INTER-RESEARCH

Authors' information