Caracterização dos assovios e modelagem de nicho ecológico do golfinho-rotador (Stenella longirostris Gray, 1828) na Região da Bacia de Santos, Brasil, Oceano Atlântico Sul

Abstract

The spinner dolphin (Stenella longirostris) is a marine mammal, which belongs to the order Cetacea. Due to the influence of human activity on the aquatic environment, it is necessary to increase the range of knowledge about cetaceans. This study aimed to describe the acoustic signal and estimate the potential distribution of the spinner dolphin in the Bacia de santos region. For this, the data collected during the Cetacean Monitoring Project (PMC) was used, based on an arrangement of APC 42-1021 hydrophones towed by a vessel, associated with the visual confirmation of the species. 836 whistles, 12 hours and 49 minutes of acoustic records were identified, from which 9 acoustic parameters were extracted: initial and final, minimum and maximum frequencies (kHz), frequency amplitude (kHz), duration (s), number of inflection, number of steps, presence / absence of harmonics. 46 occurrence points were also used to create the niche model based on five environmental variables: i) Bathymetry; ii) Inclination of the bathymetry; iii) Annual amplitude of salinity; iv) Annual temperature range; and v) Average annual chlorophyll-a concentration, collected through the public database Bio-Oracle and MARSPEC. It was observed that the parameters of duration and amplitude showed higher values, when compared with other studies, thus occurring geographic variation of the signals. The continental slope proved to be more environmentally friendly for the spinner dolphin population in BS and the amplitude of the whistles was significantly related to the environmental suitability model.