Ichthyofauna of Marinheiros Island, Patos Lagoon estuary, southern Brazil
Abstract Marinheiros is the largest island of the estuarine archipelago of Patos lagoon and is considered an area of biological relevance in the coastal region of the extreme south of Brazil. Aiming to contribute to the knowledge on the biodiversity of this important area, we conducted an ichthyofaunistic inventory in the limnic environments of the island. Twenty-seven field trips were performed between April 2015 and May 2017. A total of 12 sites representative of habitats of an intermittent shallow lagoon, intermittent pools and a perennial artificial channel were sampled. Sampling of 2,436 specimens revealed the occurrence of 30 species, including the non-native piscivorous Acestrorhynchus pantaneiro. Characiformes was the most diverse order (18 species), followed by Cichliformes (four species) and Cyprinodontiformes (three species). Characiformes was also the most numerically abundant order (77%) followed by Cichliformes (17.6%) and Cyprinodontiformes (5.1%). The species richness recorded in Marinheiros Island is is comparable to the richness observed for lotic systems of southernmost Brazilian coastal plain. The fish assemblage is composed mainly of species of limnic habits whereas few taxa of estuarine-marine-limnic and estuarine-limnic habits were recorded. In view of the presence of allochtonous A. pantaneiro and its potential to impact native species, monitoring is recommended to the ichthyofauna of Marinheiros Island and the other estuarine islands, as well as peninsular systems connected to Patos lagoon estuary.