How to characterize human influence on coastal benthic ecosystems?

Abstract

With the development of coastal human activities comes the growing need to develop methods to describe and predict their cumulative impacts on marine benthic communities locally, which rank among the most vulnerable communities in marine ecosystems. Local assessments facilitate dialogue between multiple users of the ecosystem (industries, individuals) and allow a better understanding of ecosystem components variability (e.g. benthic species, habitats) in a given region. Our objective was to evaluate the local effects (~0.01 km2 resolution) of the cumulative exposure of anthropogenic drivers on benthic species composition and diversity. Our study was conducted in the Sept-Îles region in Québec, where numerous human activities vary in local intensity (e.g. international shipping, fisheries or domestic and industrial wastes). Macro-infaunal diversity and abiotic parameters of the sediments were characterized in situ, and cumulative exposure scores were computed for each activity as a function of distance from the source, intensity and physical constraints (e.g. bathymetry). Community composition and diversity were then modelled as a function of abiotic parameters and cumulative exposure scores using Hierarchical Bayesian modelling (HMSC). We will use outcomes of these models to predict community compositions under different scenarios of human activity exposure in the bay, and to support the development of indicators of environmental status considering multiple anthropogenic drivers.