Variação espacial e sazonal das assembleias de macroinvertebrados bentônicos em um reservatório da região semiárida

Abstract

Reservoirs are artificial aquatic ecosystems built for various purposes, such as water storage, psychoculture, electricity generation and leisure. These systems can be considered a solution to the problems faced by regions with irregular rainfall regimes and water scarcity, such as the Brazilian semi-arid region. Seasonal and spatial variation can influence the biotic community. The objective of this study was to understand the effects of spatial and seasonal variation on benthic macroinvertebrate assemblages in a reservoir in the Brazilian semi-arid region. Collections were carried out in three months of each study phase, dry (september, october and november 2022) and wet (april, may and june 2023). Substrate samples (macroinvertebrates) and measurements of the physical-chemical variables of the water were carried out at ten points systematically distributed in the coastal zone of the reservoir. The collected individuals were separated from the substrate, sorted and identified to the lowest taxonomic level possible. In total, 16,099 individuals were sampled in the two phases of the study. The assemblages were different between the phases studied (p<0.05), however, spatially there was no difference (p>0.05). There was no variation between dry months, but seasonal variation was observed between full months. Individuals of the species Melanoides tuberculata (Müller 1774) were the most frequent and abundant, followed by the Lymnaea mollusk. The physical-chemical parameters of the water varied between months, however, between phases, only temperature, dissolved oxygen and ammonia varied. In this way, it was possible to observe that there was variation seasonally, but not spatially. Therefore, more studies are needed to truly understand these variations.