Significance of lipid storage levels for reproductive output in the Arctic copepod Calanus hyperboreus

Abstract

The Arctic marine copepod Calanus hyperboreus reproduces at depth during winter, with egg production fuelled entirely by internal energy reserves in the form of lipids. The present study addresses the question of whether reproductive output, in the form of total egg production or hatching success, is dependent on female size (prosome length) or lipid content at the onset of spawning in this species. Egg production of individual females and the hatching of nauplii were observed under controlled temperature and light conditions in the laboratory throughout the spawning period from December to March. There was a positive relationship between female size and total egg production, and an even stronger positive relationship between initial lipid content and total egg production. No relationship was found between hatching success and either female size or lipid content. One implication of these findings is that increased water temperatures in the Arctic might have a direct negative impact on an important life history trait such as size at maturity, resulting in reduced fecundity in this species.