Early summer near-shore fish assemblage and environmental correlates in an Arctic estuary

Abstract

Abstract Knowledge of reference conditions and species–environment associations is required to ascertain ongoing aquatic biodiversity changes in Arctic regions. The objective of this study was to establish a baseline of fish community structure (species composition, incidence and relative abundance) in relation to salinity, pH and temperature gradients in an Arctic estuary, the Husky Lakes, Canada. Sampling involved an early-summer, standardized, experimental netting survey around the entire perimeter of all estuary basins and peninsulas. Detrended canonical correspondence analysis (DCCA) was used to evaluate species–environment associations. The ecosystem sustains an abundant and diverse fish community, characterized by co-dominance of coregonids and a marine schooling fish, Clupea pallasii , and high abundance of freshwater/freshwater-amphidromous species in the innermost basins. Highest richness and total abundance were related to mixing conditions, warmest temperatures, connectivity to nearby ecosystems, and diversity in species life histories. Salinity determined spatial patterns of fish species abundance and distribution. The incidence of freshwater fish was limited by the availability of low salinity habitat and potential community interactions. These fish, particularly Salvelinus namaycush and Thymallus arcticus , are considered as the most vulnerable to changes in freshwater habitat availability. The fish assemblage reflects environmental information from surrounding fluvial, freshwater, coastal marine and catchment ecosystems, and is thus a prime candidate for monitoring environmental change in the region. The results provide a benchmark against which future studies of fish communities can be compared to evaluate potential effects of climate change and anthropogenic development on fish populations from Husky Lakes and similar Arctic aquatic ecosystems.