Hot deals at sea: responses of a top predator (Bottlenose dolphin, Tursiops truncatus) to human-induced changes in the coastal ecosystem

The main response of top predators to human-induced environmental changes is often behavioral. Although human activities regularly impose a disturbance on top predators, they can also be a source of reliable and concentrated food resources for species with a high degree of behavioral plasticity. This study represents the first assessment of the influence of these resources on migratory patterns and social interaction of a marine top predator, the common bottlenose dolphin, Tursiops truncatus. Pollock's closed robust design models and association analyses were applied to data collected over 9 consecutive years of research in a coastal area subject to significant use and pressure by humans. Photo-identification data were collected year-round during 955 boat-based surveys, resulting in 1638 common bottlenose dolphin group encounters. Results of this study revealed a significant upward trend in density of bottlenose dolphins, preferences for a coastal area with higher human pressure, and a reduction of the social interactions associated to a temporal switch to the food sources provided by human activities. The observed link between human activities and changes in common bottlenose dolphin behavior aim to contribute to a better understanding of the ecology of a marine top predator and provide some of the needed baseline data, from which effective management and conservation strategies can be designed.