Comparing demersal fish and large mobile decapod crustacean assemblages in nearshore marine habitats across a boreal – sub-Arctic gradient using baited cameras

Arctic and sub-Arctic ecosystems are experiencing changes in environmental conditions, altering marine biodiversity through shifts in species distributions and composition. Coastal ecosystems in northern environments are vulnerable to continued environmental change, but the remoteness of these areas and challenges associated with sampling shallow, structurally complex habitats have limited studies on nearshore communities. We compared the composition and relative abundances of nearshore assemblages in 7 coastal locations spanning 10° latitude of boreal and sub-Arctic habitats in Newfoundland and Labrador, Canada, using baited remote underwater video (BRUV). We identified 14 taxa, including 11 fish species and 3 decapod crustaceans. Species richness and diversity was generally higher in southern relative to northern locations, and spatial distributions differed across taxa. Greenland cod Gadus macrocephalus ogac and large cottids Myoxocephalus spp. were the most common taxa in northern areas and the only species observed across the entire environmental gradient. In contrast, we observed Atlantic cod G. morhua, winter flounder Pseudopleuronectes americanus, and cunner Tautogolabrus adspersus exclusively in southern locations. In addition to community variability across locations, habitat differences contributed more to variation in community-level abundances than to the abundances of most individual taxa. BRUVs provided an effective method for comparing nearshore assemblages across northern coastal habitats that are challenging to other common sampling methods. Further studies incorporating BRUVs could track variability in nearshore assemblages over longer time scales and offer an accessible method for coastal communities to monitor change across habitats.