Análise do ruído antropogênico sobre uma população de boto cinza (Sotalia guianensis), (Van Benédén, 1864) na paisagem acústica da Baia de Todos os Santos - Bahia, Brasil

Abstract

Sound is linked to quality of life and through it various organisms perform essential functions for their survival, such as the Guiana dolphin (Sotalia guianensis) smaller representative of the Delphinidae family that has a preference for protected environments such as bays and estuaries. Distant behavior in relation to the approach of vessels makes it difficult to study this species in its natural environment and therefore acoustic monitoring becomes an important tool in the study of this species, so that the need to know the sound environment in which these species are inserted becomes evident. Soundscape Ecology is a line of research who has been studying these sound environments and their interference in the functioning of different populations and communities present in different media. The present study aims to understand the relationship between anthropogenic and biological sounds in the Todos os Santos Bay, located in the state of Bahia, describing the sound emitted by each source of anthropogenic noise recorded and evaluating the areas of occurrence of the guiana dolphin together. with the distribution of these noises. To this end, 19 field trips were made between October 2016 and May 2018, the recordings were made onboard a 30 ft (10 meter) Cal ocean sailboat and the recordings were made using a TASCAM recorder DR-40 connected to a HTI 90 hydrophone that was released into the water whenever the team spotted an acoustic collection point, which could be anthropogenic or biological, in the laboratory. These data were analyzed by the RAVEN 1.5 program and geographic data were generated. using the program QGIS 3.6.0-Noosa. A total of 58 acoustic points and 88 sighting points were collected, where 8 distinct anthropogenic source types were recorded, being 7 vessels and 1 underwater bomb. For the spatial analysis 3 maps were made, one indicating the places of occurrence, the other the distribution of the background noise and the third map was the result of overlapping the previous two maps. The analysis showed that the anthropogenic noises modify the environment in different ways depending on the emitting source and that most of the sightings were recorded in places that presented lower background noise rate, indicating a possible preference of these animals for less noisy areas.