Ichthyofauna of a protected Atlantic Forest area in Northeastern Brazil: taxonomic inventory and conservation implications

Protected areas play a fundamental role in safeguarding freshwater biodiversity, particularly in highly threatened tropical ecosystems such as the Atlantic Forest. The Michelin Ecological Reserve (REM) in northeastern Brazil encompasses Atlantic Forest remnants drained by the Igrapiúna and Serinhaém river basins, within the Northeastern Mata Atlântica freshwater ecoregion. Despite several biological studies conducted in the reserve, its freshwater fish fauna has never been comprehensively assessed taxonomically. This study aimed to conduct a taxonomic assessment of the REM ichthyofauna and discuss conservation aspects of the fish fauna and sampled aquatic environments. We examined 287 specimens obtained during surveys conducted in September and November 2012 and August 2023. The 2012 samples comprised 36 specimens deposited in the ichthyological collection of the Museu de História Natural da Bahia. In 2023, 251 additional specimens were collected specifically for this study at ten localities using landing nets and a trawl. Environmental characteristics, including water depth, width, color and flow, riparian vegetation, and substrate, were recorded during field sampling. A total of 15 species belonging to 13 genera, 11 families, and six orders were recorded. Characiformes and Siluriformes were the most species-rich orders, and Characidae and Loricariidae were the most species-rich families. Astyanax was the most species-rich genus, represented by three species, while Astyanax sp. was the most abundant taxon. Characidium sp., Hyphessobrycon itaparicensis, Hypostomus unae, Leporinus bahiensis, and Sicydium punctatum represent the first records for the Igrapiúna and/or Serinhaém river basins. No native species recorded is currently listed as nationally threatened, and only one non-native species was detected. The sampled aquatic environments were generally well-preserved and maintained the characteristic riparian vegetation of Atlantic Forest remnants. These findings expand taxonomic and distributional knowledge of freshwater fishes and reinforce the conservation importance of the REM.