Spatial behavioural response of coastal bottlenose dolphins to habitat disturbance in southern Brazil

TitleSpatial behavioural response of coastal bottlenose dolphins to habitat disturbance in southern Brazil
Publication TypeJournal Article
Year of PublicationSubmitted
AuthorsAgrelo, Macarena, Daura-Jorge Fábio G., Bezamat Carolina, Silveira Thiago C. L., de Castilho Pedro Volkmer, Pires José Salatiel R., and Simões-Lopes Paulo C.
JournalAquatic Conservation: Marine and Freshwater Ecosystems
ISBN Number1052-7613
EndNote Rec Number12615
Abstract

Abstract A small population of coastal bottlenose dolphins (Tursiops truncatus gephyreus) inhabits the inland waters of Laguna, southern Brazil. A subset of this population interacts with artisanal fishermen. This specialized foraging tactic structures dolphin society into ‘cooperatives’ (participants of the interaction) and ‘non-cooperatives’ (non-participants). Between 2012 and 2015, a bridge was constructed in Laguna over an important core area for dolphins. Photo-identification and georeferenced data collected on boat surveys, conducted both before and during bridge construction, were used to evaluate changes in both ‘cooperative’ and ‘non-cooperative’ dolphin distribution. Changes in dolphin distribution were analysed with kernel densities and hurdle models. A grid of 120 cells of area 1 km2 was used to model dolphin distribution, and the minimum distance from the grid cell centre to the bridge and to the area of gillnet use were defined as explanatory variables of human activities. Habitat descriptors (depth and distance) from the lagoon margin were also considered in the model procedure. Dolphin distribution patterns shifted between periods. A core area used by ‘non-cooperative’ dolphins near the bridge construction works disappeared. The effects of habitat descriptor and anthropogenic activity on dolphin distribution also differed between periods. Before bridge construction, the abundance of ‘non-cooperative’ dolphin was higher close to the bridge area (p