Aninhamento de insetos aquáticos associados ao substrato rochoso em corredeiras

Abstract

Streams harbor heterogeneous ecosystems, resulting in a diversity of microhabitats that provide sources of shelter and food. In streams, environmental variations exert an adaptive selection on benthic habits, with organisms nesting according to their habitat preferences. In this context, the study aimed to characterize the structure of the aquatic insect assemblage associated with rocky substrates in a stream mesohabitat, with the objective of verifying whether substrate size influences the community's nested pattern. Therefore, 30 rock samples were collected, and the height, width, and length of each were measured. The rocks were washed using wash bottles to remove insects adhered to their surfaces. Subsequently, the insects were stored in 70% alcohol and, in the laboratory, identified to the lowest possible taxonomic level. Ecological descriptors were used to characterize the structure of the aquatic insect community. The NODF (Nestedness metric based on Overlapping and Decreasing Fill) was tested to assess the presence of a nesting pattern. To check correlations between the abundance and richness of aquatic insects based on rock measurements, the non-parametric Spearman correlation test was applied. A total of 603 aquatic insects were sampled, including 595 larvae and 8 adults, distributed across eight orders, 18 families, and 31 genera. The results indicate that the distribution of aquatic insects varied and showed a significant nested pattern as a function of substrate dimensions, corroborating with the assumption that granulometry influences the richness and abundance of individuals contained within the substrate.