Redundância funcional e vulnerabilidade funcional de macroinvertebrados ao longo do gradiente de precipitação pluviométrica em reservatórios do semiárido

Abstract

The marked loss of biological diversity in ecosystems has raised discussions about its impact on the functioning of ecological systems. Because the homogenization of species results in loss of functions that influence the processes in which they are involved. However, it is expected that functional redundancy, ie species that have similar functional attributes, guarantees the permanence of functions within ecological systems. The study was carried out in eight reservoirs inserted in a rainfall gradient established from historical information from Wordclim 2 and AESA databases. With the objective of evaluating the functional redundancy and functional vulnerability of macroinvertebrates along the environmental gradient of rainfall. Testing the hypothesis that the reduction in rainfall will increase the functional redundancy and functional vulnerability of macroinvertebrates. The collections were carried out in May 2018, at the end of the rainy season, sampling aliquots of the macroinvertebrate community at seven points in the coastal region of each reservoir. The rainfall of the month of collection was used, as well as the macroinvertebrate abundance matrix for statistical analyses. Seven functional attributes linked to water scarcity were chosen: Body Size, Habit, Feeding Strategy, Hemoglobin, Dispersion, Reproduction and Larval Stage. Functional indices were calculated: Functional Redundancy (FR), Excessive Functional Redundancy (FOR), Functional Vulnerability (FV). The functional attributes of the community allowed the combination of 128 Functional Entities (FEs), however the 2,689 organisms were distributed in only 15 functional entities, regardless of the functional richness, with the highest predominance of FEs representing 25% of the general pool of reservoirs. We observed high values of functional redundancy and functional vulnerability in all reservoirs, where about 60% of the EFs had only one taxa. However, the environmental gradient did not exert a significant influence on the functional indices analyzed. However, the fragility in the diversity of attributes presented by the macroinvertebrate community of semi-arid reservoirs was evidenced. Reinforcing the importance of a clear and cautious interpretation of the role of functional redundancy in ecosystem functioning