Seasonal changes in diet and lipid content of northern sand lance Ammodytes dubius on Fyllas Bank, West Greenland

摘要

ABSTRACT: Sandeel (Ammodytes spp.) are forage fishes and form a crucial link in the flow of energy from phytoplankton to marine top predators in the North Atlantic. The nutritional value of the sandeel is linked to the presence of lipid-rich zooplankton species, which makes their trophic role vulnerable to climate-induced changes in the zooplankton community. We provide the first description of diet and lipid accumulation of the northern sand lance Ammodytes dubius Reinhardt, 1837 in southwest Greenland (64°N) during a growing season. Sampling occurred in May, August and September 2013, and differences in diet and lipid content were found in relation to season, gender and ontogeny. In terms of numbers and biomass, nauplii constituted the vast majority of prey in May, whereas copepods (primarily large Calanus spp.) dominated in August and September. Groups of larger prey (euphausiids and amphipods) were only found late in the season and primarily in sandeel larger than 16 cm. Mean lipid content (% DW) was at a minimum in May for both mature (males: 5.6%, females: 6.4%) and immature sandeel (3.9%), and peaked in August for mature individuals (males: 21.7%, females: 24.2%) and in September for juveniles (19.8%). Sandeel condition responds quickly to changes in prey availability and can be used as an indicator sensitive to of productivity and environmental change on the banks in West Greenland. In the light of rapid climate changes in Arctic marine ecosystems, the present findings may serve as a baseline for future monitoring of the productivity of pelagic ecosystems in West Greenland.