Contamination Profile and Health Status of Mya arenaria in the Saint-Lawrence River-Saguenay Fjord Marine Park

Clams represent an important part of the marine benthic community and as food sources for invertebrates (worms, amphipods), fish, and marine mammals. The purpose of this study was to examine the contamination and health status of feral Mya arenaria clam populations at sites of anthropogenic pollution (harbors), high residency Beluga whale area and a reference under no direct contact of pollution. Intertidal clams were collected for nanoplastics (NPs), dibutylphthalate (DBP), metal contamination and health status assessment. Health status consisted in the evaluation of oxidative stress, protein aggregation, esterase, carbonic anhydrase at the molecular level followed by morphological assessments (shell mass, condition factor, growth index) and resistance to air emersion. The data revealed that clams collected from polluted sites (marina and downstream urban cities) had elevated levels of NPs, DBP, Cd, Ce, Fe, Cu, Sn and Zn compared to a reference site. Surprisingly, the Beluga high residency area site was also contaminated by these contaminants (with the exception of Cd) especially for Sn, NPs and DBP. These clams contained elevated levels of peroxidase activity, protein aggregation, esterase, (mantle) carbonic anhydrase and accumulated lipids. The clams displayed at least at one polluted or whale residency site, decreased CF, shell mass ratio, air survival time and increased growth index. Cluster analysis revealed that the above contaminants were strongly associated with carbonic anhydrase, esterase, peroxidase and protein aggregation changes but less so towards morphological changes. In conclusion, feral clam populations are contaminated by plastics compounds including and shows signs of physiological stress as shown with reduced shell mass.