The ecological role of species can vary among populations depending on local and regional differences in diet. This is particularly true for top predators such as the bottlenose dolphin, which exhibits a highly varied diet. Local dietary assessments are therefore critical to fully understand the role of this species within marine ecosystems. Here, stomach content analyses and stable isotope analyses were combined to describe bottlenose dolphins diet in the Gulf of Cadiz.

Organochlorine (OC) pesticides and the more persistent polychlorinated biphenyls (PCBs) have well-established dose-dependent toxicities to birds, fish and mammals in experimental studies, but the actual impact of OC pollutants on European marine top predators remains unknown. Here we show that several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery.