An overview of seabirds in the Santos Basin, Brazil: species, threats, and current trends in studies

Abstract

The Santos Basin in eastern Brazil is adjacent to the largest human populations in the southwestern Atlantic Ocean, with several potential threats to marine vertebrates. In this study, we provided a systematic bibliographic review and integrated unpublished primary datasets to provide an overview on species, research topics and gaps, and threats to seabirds in the Santos Basin. Bibliographical sources were used for species recorded within the limits of the basin, while species census data were obtained through research and monitoring projects. We analyzed 156 studies from 1914 to 2021. An increase in the number of publications was observed from the 2000s onward (> 80%), with the state of Santa Catarina showing the highest number of publications (56%) on seabirds. Notes and Records (27%), Population and Community Structure (22%), and Fishing (11%) were the main subjects studied. Among the 76 seabird species reported in the Santos Basin (~2/3 of the species reported in Brazil), Procellariiformes was the most prevalent order (51%), including 14 species listed as threatened, either globally or nationally. Resident (28%) and long-distance migratory species, such as visitors from the Southern (39%) and Northern (17%) Hemispheres and Europe (12%), were widely recorded in the region, as well as vagrant species. The inclusion of different data sources allowed broadening the geographic cover used by species to consider both coastal (predominating in previous studies) and offshore areas. The association of seabird distribution with oceanographic and meteorological features should be addressed in future studies, as should studies on the impact of fishing and pollution on a range of common species.