Investigating inter-annual variation in cobble-bottom assemblages of fish and decapod crustaceans in the Beaver Harbour region of the Bay of Fundy over the last 17 years

Abstract

Gradual or sudden changes in biotic or abiotic factors can drive inter-annual variation in benthic communities. Despite their role as important nurseries, subtidal cobble ecosystems are understudied because of their interstitial nature, making monitoring difficult. This study quantifies changes in a community of fish and decapod crustaceans colonizing cobble-filled bio-collectors deployed from 2007-2024 at four sites in the Beaver Harbour region of the Bay of Fundy. Fish + large decapods at all sites, and fish + large decapods + small shrimp at both Beaver Harbour Lighthouse and Beaver Harbour East sites, showed significant seriation, progressively becoming dissimilar from the initial community. These two sites also showed two more pronounced sudden community shifts during this time. Community trends were mainly driven by changes in abundances of three fish (Cunner, Radiated Shanny, Shorthorn Sculpin) and two crab (Jonah, Atlantic Rock) species. These findings provide information on inter-annual changes of an understudied cobble bottom community potentially linked to condition changes in the Bay of Fundy.