Riqueza e abundância de gastrópodes e trematódeos associados em áreas ao redor da região dos Lençóis Maranhenses, Brasil

Abstract

Mollusks constitute the second largest animal phylum, surpassing 100,000 species and ranked only below the arthropods. Among the phyla within this significant group of animals, limnic gastropods stand out, known in environmental and epidemiological contexts for their strong parasitic associations with trematode helminths. This study aimed to explore the gastropod and trematode fauna and their interactions in the Lençóis Maranhenses region. The research was conducted across 28 defined locations within the Lençóis Maranhenses, spanning the municipalities of Santo Amaro do Maranhão, Barreirinhas, and Paulino Neves. Gastropods were collected from freshwater environments, including restinga forests, fields, rivers, tributaries, and dunes. Species richness and abundance rates were analyzed. ANOVA testing was applied to assess differences in gastropod abundance among the studied areas, along with an evaluation of trematode infections and correlations between coliforms and abiotic factors with gastropods. A total of 3,483 gastropod specimens were collected, identifying three species: Biomphalaria straminea, Melanoides tuberculata, and Drepanotrema lucidum, along with Pomacea spp. and Physa spp. The species B. straminea, representing 51% of the collected specimens, was the most abundant. Trematode presence was detected in 0.34% of the mollusks, with the highest incidence in M. tuberculata. ANOVA results indicated no statistically significant difference among mollusk populations, although the dry season presented a higher number of mollusk specimens. The findings reveal the presence of total and thermotolerant coliforms, particularly in Barreirinhas and Paulino Neves, suggesting possible sewage contamination among the evaluated water bodies. This research contributes to the understanding of regional biodiversity, highlights significant taxa involved in environmental and health issues, and underscores the need for ongoing monitoring of these species' occurrence sites.