Spatial marine meiofauna variations in areas undergoing different disturbance levels on the Amazon coast

The Brazilian coastal zone comprises several types of environments, including lagoons and beaches, chosen for this study, which evaluate benthic meiofauna spatial distribution patterns in three areas, suffering different disturbance levels, throughout the Brazilian Amazon coast. Sediments from three areas (São Marcos Beach – Low level of disturbance; Calhau Beach – Medium level of disturbance; and Jansen Lagoon – High level of disturbance), in São Luís city (Maranhão, Brazil), were sampled for meiofauna assessments, granulometry and organic matter analyses. A total of 7,254 meiofaunal organisms were identified, 4,371 at São Marcos Beach, 1,856 at Jansen Lagoon, and 1,027 at Calhau Beach. The findings indicate that richness, density, and community structures differed significantly among the sampled areas. Nematoda and Copepoda were the most abundant groups. Copepoda stood out in São Marcos Beach compared to other taxa. Nematoda dominated in Jansen Lagoon. Calhau Beach presented the lowest density and richness values, with Tardigrada as the predominant meiofaunal group. Additionally, the composition of meiofauna was influenced by environmental variables, such as salinity, OM, sediment grain size and nitrate concentration, as well as anthropogenic activities taking place in the sampled areas. Considering the lack of studies in the region with this focus, it is expected that the results presented will contribute to public policies development aimed to conservation of the coastal zone in São Luís.