Inventário das espécies de anfíbios da Região dos Cocais em áreas semi-urbanizadas do município de Bacabal, Maranhão

Abstract

Amphibians represent the third-largest group of vertebrates worldwide, comprising over 9,000 species, with approximately 40% found in the Americas. In Brazil, the amphibian fauna consists of 1,251 species grouped into 121 genera and 25 families across three orders: Anura, Caudata, and Gymnophiona. The *Mata dos Cocais* (Babassu Palm Forest) region features a unique landscape characteristic of the state of Maranhão, defined by the prominent presence of babassu palm groves; as a transition zone situated between two biomes, it shares elements of their flora and fauna, making it a major biodiversity hotspot. Amphibians play an indispensable ecological role in maintaining ecosystem balance; they are crucial for insect population control, nutrient cycling, and food web dynamics, while also serving as excellent bioindicators. They maintain a direct relationship with aquatic environments throughout their life cycle—from reproduction to adulthood—with population dynamics strictly tied to water. The degradation of forest areas due to human activity primarily impacts the quality of aquatic environments in peri-urban areas. This study aimed to catalog amphibian species in the Cocais forest within the municipality of Bacabal, Maranhão, across various semi-urban sites. Methodologies included TimeConstrained Searches (TCS) and pitfall traps (with drift fences), supplemented by records from "third-party encounters" and "incidental encounters" throughout the municipality's peri-urban zone. Additionally, the study sought to correlate species distribution with the level of human alteration (anthropization) at each sampled site. The inventory recorded 272 individuals representing 21 species, 12 genera, and five families. The most frequently sampled families were Hylidae, Leptodactylidae, and Bufonidae. The species exhibiting the highest abundance were Leptodactylus macrosternum, Boana raniceps, and Dendropsophus minusculus. Area 3 showed the highest diversity and evenness indices. The greatest similarity was observed in the clustering of Areas 1 and 2, whereas the most distant grouping involved Areas 1 and 3. TimeLimited Search (TLS) was the most effective sampling method for recording species. The results revealed a significant variety of species at the target sites; however, these were primarily synanthropic or potentially resistant to environmental alteration. This survey represents a pioneering initiative regarding the sampling of amphibian species in the Cocais Forest of Bacabal, Maranhão, filling an important gap, contributing relevant data to the scientific literature, and serving as a starting point for future research.