Diet and Reproductive Output in Arctic Molluscs: the Importance of Ice Algae and Phytoplankton (DREAM)

Algae that are associated with the arctic sea ice (ice algae) can constitute a significant fraction of total primary production, and play a fundamental role in polar ecosystems. The recently documented reduction of ice coverage may result in a significant shift in the relative contributions of ice algae versus phytoplankton as food sources for benthic communities. There are biochemical differences between ice algae and phytoplankton, in particular a higher concentration of polyunsaturated fatty acids (PUF As) in ice algae. Since the reproductive process is energetically costly, and eggs and larvae are rich in fatty acids, we expect that the loss of such a high-quality food source will be observable in the reproductive development. We examine the potentia l consequences of this reduction in ice algae as a food source to the reproduction of a common benthic bivalve, Macoma calcarea, in the field and a laboratory experiment. We will trace the reproductive development of bivalves in the field in relation to s easonal inputs of ice algae in Kongsfjorden (Ny Ålesund, Svalbard), and then experimentally determine differences in reproduction in bivalves fed different diets in controlled laboratory conditions.