Temporal change in the molluscan assemblages (bivalves and gastropods) of Frobisher Bay, Nunavut, Canada, over 50 years

Abstract

Long-term studies provide an effective way to assess the ecological impacts of decades-long environmental change in Arctic coastal benthic environments, but are rarely undertaken in the Canadian Arctic. In light of this, historical datasets can be compared with modern samples to examine temporal differences in benthic community structure. Frobisher Bay, Nunavut, provides a unique opportunity to use a historical census to examine the impacts that long-term environmental changes have had on the marine benthos. Between 1967 and 1976, and in 2016, infaunal samples were collected in inner Frobisher Bay and were compared to determine how the molluscan assemblages have changed between the two time periods. Molluscan assemblages in two regions of inner Frobisher Bay (Iqaluit and Cairn Island) were examined to minimize sampling discrepancies between the two time periods. A long-term increase in mean annual air temperature and a decline in the length of the ice cover season were observed. Both regions exhibited some change in sediment composition and quality as well as in molluscan assemblage between the two time periods, and species diversity indices also indicated some change between these time periods. Both the 1967–1976 and 2016 molluscan datasets provide a baseline for future long-term studies in a changing Arctic.