Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975-2015.

Luis Felipe S P Mayorga,Luciano W D Reis,Wilson Luiz Chevitarese Meirelles,Ralph E T Vanstreels,Salvatore Siciliano,Flavia C F Pinheiro,Luiz M B Costa,Renata C C Bhering,Natália Mamede,Alessandro Trazzi,Alan Marques Ribeiro

doi:10.3897/zookeys.948.50468

Abstract

Espírito Santo state is located on the eastern margin of Brazil, in a transitional tropical-subtropical area (18°S–21°S) dominated by oligotrophic waters. With the exception of humpback whales (Megaptera novaeangliae), the cetacean community of Espírito Santo has been understudied. In addition to the chronic impacts from fisheries, marine pollution, urban development, and coastal habitat degradation, in November 2015 the cetacean communities of Espírito Santo were challenged by the greatest environmental disaster in Brazil’s history. The Mariana dam disaster caused 60 million cubic meters of mining waste to be washed into the Doce River, which ultimately flowed to the coastal waters of Espírito Santo, with a high concentration of heavy metals. This study reviews and updates information on cetacean strandings in the state of Espírito Santo (excluding humpback whales) prior to this disaster. From 1975 to September 2015, there were 461 recorded cetacean strandings, representing 20 species. An average 1.18 strandings per 100 km per month were recorded since a state-wide daily beach survey program was implemented in October 2010, contrasting with the 0.14 strandings per 100 km per month in previous years. Six species comprised the majority (94.7%) of stranding events: Guiana dolphin (Sotalia guianensis), Franciscana (Pontoporia blainvillei), rough-toothed dolphin (Steno bredanensis), bottlenose dolphin (Tursiops truncatus), sperm whale (Physeter macrocephalus), and melon-headed whale (Peponocephala electra). Oceanic cetaceans stranded most frequently on the southern portion of Espírito Santo, where the continental platform is narrower, whereas the strandings of coastal cetaceans such as Guiana dolphins and Franciscanas were concentrated near estuaries, especially the Doce River. This is particularly concerning in face of the Mariana dam disaster, which drastically altered the estuarine and coastal environment associated with the Doce River.

Highlights

Records of cetacean strandings provide reliable data on the occurrence of species and are good indicators of species richness, relative abundance and spatial distribution (Maldini et al 2005, Pyenson 2010, 2011), and can be used to inform the management of marine resources (Leeney et al 2008, Peltier et al 2014)
While studies are still under way in Cetacean stranding baselines for Espírito Santo, Brazil order to evaluate the impacts of the Mariana dam disaster on the marine environment of Espírito Santo, this study provides a compilation of the data on cetaceans strandings in the 40 years preceding the disaster, providing a historical baseline for the region
Odontoceti corresponded to 456 individuals (98.9%) and 17 species (85%), and Mysticeti corresponded to 5 individuals (1.1%) and 3 species (15%)

Summary

Introduction

Records of cetacean strandings provide reliable data on the occurrence of species and are good indicators of species richness, relative abundance and spatial distribution (Maldini et al 2005, Pyenson 2010, 2011), and can be used to inform the management of marine resources (Leeney et al 2008, Peltier et al 2014). Cetaceans may be impacted by artisanal fisheries (de Freitas Netto and Di Beneditto 2007, 2008, de Freitas Netto and Siciliano 2007), marine traffic (e.g., acoustic pollution, collisions) (Pinheiro et al 2019) and changes in geomorphology waves due to urban occupation of coastal areas (Albino et al 2001, Ribeiro and Siqueira 2012). In November 2015, the marine environment of Espírito Santo suffered drastic impacts from the greatest environmental disaster in Brazil’s history, the Mariana dam disaster. While studies are still under way in Cetacean stranding baselines for Espírito Santo, Brazil order to evaluate the impacts of the Mariana dam disaster on the marine environment of Espírito Santo, this study provides a compilation of the data on cetaceans strandings in the 40 years preceding the disaster, providing a historical baseline for the region

Methods

Results

Conclusion