A computational model of guiana dolphin (Sotalia guianensis) responses to the sound fields produced by noise sources

Abstract

There has been an increasing concern on the consequences of continuous exposure of marine mammals to noise. Relatively little is known about how they adjust their movements and behavior to deal with the variability of noise fields. Therefore, modeling the sound propagation of noise sources is essential to assess their potential risk on marine mammal survival. Guiana dolphins Sotalia guianensis were used as biological models of interaction with noise from boat engines integrated with environmental data. Simulations were performed at ESME, a computational modeling environment developed by the Office of Naval Research and Boston University. ESME brings together into a single framework advanced models of sound propagation from selected noise sources running against simulated individual animals, whose behavioral state transitions were retrieved from peer-reviewed sources and converted in Marine Mammal Movement and Behavior algorithms. The target study area was an estuarine coastal system in Southeastern Brazil. A generic small odontocete model was employed, as there was no available specific model for guiana dolphins. Transmission loss profiles demonstrated that the noise attenuation was relatively fast in the area and their effects on the movement and distribution of the target species seemed limited. The simulations indicated that the dolphins did not suffer significant behavioral stress from being exposed to boat sound sources.