The effects of mercury on the dynamics of the peracarida community in a temperate coastal lagoon (Ria de Aveiro, Portugal)

•Suprabenthos was negatively affected in terms of biomass, diversity and production.•Mysids and isopods dominated the suprabenthic community.•Amphipods were more sensitive to higher Hg concentrations.•Isopods and amphipods were the taxa with higher mercury body burden.•Suprabenthos is a vehicle of mercury transference through the estuarine trophic web. This study focuses on the impact of mercury on the dynamics and bioaccumulation patterns of suprabenthic peracarida community along a mercury gradient. Suprabenthic peracarida was negatively affected in terms of biomass, diversity and productivity. Mysids including Mesopodopsis slabberi dominated the community, presenting a regular distribution along the Hg gradient, so are considered tolerant species to mercury. Then, isopods, the second most abundant group, dominated in the most contaminated areas being considered also a tolerant group. Contrarily, amphipods were negatively correlated with higher Hg concentrations, dominating in the intermediate areas, thus are considered more sensitive species. In addition, isopods and amphipods were the taxa with higher mercury body burden, followed by mysids. This paper highlights the importance of suprabenthic peracarida as a vehicle of mercury transference through the estuarine trophic web since it is a main link between benthic and pelagic levels and an essential food resource for numerous fish species.