INVENTÁRIO DA ICTIOFAUNA DA BACIA DO RIO TIBIRI, SÃO LUÍS, AMAZÔNIA MARANHENSE

Abstract

Brazil's rich aquatic biodiversity has been the target of several studies with the description and new records of fish species, although Neotropical aquatic ecosystems have been the target of intensified anthropic actions with a potential increase in habitat loss. The objective of this work was to inventory the fish species that occur in the Tibiri river basin, in the municipality of São Luís, Maranhão Amazon. The study was carried out based on scientific collections along the Tibiri River basin on São Luís Island, also known as Ilha Grande, Ilha do UpaonAçu and Ilha do Maranhão, from August 2021 to July 2024. fish traps, trawl nets, seine nets, sieves and fishing nets of various mesh sizes are used with fishing gear. The collected fish were euthanized with a solution of water and tricaine methanesulfonate (TMS), fixed in 10% formaldehyde and subsequently transferred to the Ichthyofauna and Integrated Pisciculture Laboratory of the State University of Maranhão (LABIPI-UEMA) for preservation in alcohol. diluted to 70% and identification to the lowest possible taxonomic level based on specific literature. Taxonomic classification, taxa, names, In this study, 7,465 fish specimens were collected in the Tibiri River basin, representing 65 species included in 17 orders and 37 families. The order Acanthuriformes presented the greatest species richness, followed by Carangiformes, Clupeiformes and Gobiiformes. Of the 65 species recorded, three are nonnative to the region: Megaleporinus macrocephalus, Butis koilomatodon and Poecilia reticulata, documenting one of the most worrying human actions for natural ecosystems: the introduction of exotic species. The most abundant species was Rhinosardinia amazonica, while species such as Megalops atlanticus, Scomberomorus cavalla and Bagre bagre were rarely collected, in addition to being categorized by ICMBio as Vulnerable (VU) and Near Threatened (NT), respectively. Additionally, a potentially undescribed species, Hemigrammus sp., was recorded. The study emphasizes that the Tibiri River basin is home to a high richness of fish species, however, it is harmed by serious human activities, facing problems in conserving its species and maintaining the natural characteristics of its landscape. Our results suggest the need for additional studies that integrate taxonomic, molecular and ecological approaches to improve the conservation of the Tibiri River basin, as well as to mitigate human pressures that influence this ecosystem.