Stable isotopes of carbon, nitrogen, sulphur, and chemical contaminants in common dolphins Delphinus delphis from European Atlantic waters sampled between 2017 and 2023

Whenever possible, tissue samples of skin, muscle, kidney, liver and blubber were collected on a total of 227 individuals between 2017 and 2023. These individuals encompass 117 stranded animals recovered by local stranding networks and 3 bycaught individuals directly observed on board (dead animals), likely living and feeding on the continental shelves of four European countries (France: English Channel and Bay of Biscay, Spain and Portugal: Atlantic coast, and Ireland).

In addition, 107 remote biopsies (skin and bubbler samples only) were collected on living individuals from offshore waters (i.e. beyond the continental slope) in the Bay of Biscay and around the Madeira archipelago. Stable isotope ratios of carbon, nitrogen and sulphur were measured in the skin and/or in the muscle tissue. Concentrations in 16 essentials and non-essentials elements including mercury (Hg) were measured in skin (Hg only), liver and/or kidney.