Diversity of cetaceans as tool in monitoring environmental impacts of seismic surveys

Abstract

New information about the effects of seismic surveys on cetaceans is causing increasing concern about the impact of this type of activity on marine life. The effects described include behavioral responses and changes in vocalization patterns, diversion of migratory routes, damage to the auditory system, and an increase in strandings. Although such effects could affect the diversity of species in areas where seismic research has been carried out, there is no scientific information on this subject. This study aims to evaluate the relationship between seismic surveys, oceanographic data and diversity of cetaceans recorded in Brazil following the stepping up of seismic survey activities between 1999 and 2004. The study is based on oceanographic data from the Pilot Research Moored Array in the Tropical Atlantic (PIRATA Project), sightings made during seismic surveys, progress reports from Brazilian research projects to the International Whaling Commission, Brazilian seismic survey reports available at the Escritório de Licenciamento de Petróleo e Nuclear of the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (ELPN-Ibama) and complementary data from the webpage of the Agencia Nacional de Petróleo e Gás Natural (ANP). The results suggest a decrease in the diversity of species in the face of an increase in the number of seismic surveys during the years 2000 and 2001, even though there was no significant change in oceanographic patterns in this period, and that a relationship exists between diversity of cetaceans and intensity of seismic surveys between 1999 and 2004. It is recommended that data collection be improved in order to evaluate this hypothesis properly. The results suggest that species diversity might be used as a long-term indicator of the impact of seismic surveys on cetaceans.