Winter-spring feeding and metabolism of Arctic copepods: insights from faecal pellet production and respiration measurements in the southeastern Beaufort Sea

摘要

Faecal pellet production (FPP) and respiration rates of Calanus glacialis, C. hyperboreus and Met-ridia longa were measured under land-fast ice in the southeastern Beaufort Sea during the winter-spring transition (March-May 2004) prior to the phytoplank-ton spring bloom. Despite different overwintering and life cycle strategies and remaining low concentrations of suspended chlorophyll a and particulate organic matter, all species showed increasing FPP rates in spring. A corresponding increase in respiration was only observed in C. glacialis, while respiration remained constant in C. hyperboreus and M. longa. In C. glacialis and C. hyperboreus calculated ingestion covered respiratory expenditures. The constancy of the oil sac volume in M. longa suggests that the animals fed during winter-spring. Pre-bloom grazing as shown here seems to acclimate the copepod populations physiologically for the upcoming high feeding season, so that they are able to resume maximum grazing and reproduction as soon as the phytoplankton bloom is initiated.