Temporal variation of phytophilous Chironomidae over a 11-year period in a shallow Neotropical lake in southern Brazil

Abstract

Small and shallow lakes make up most of the lake-covered area in the world, and immature Chironomidae generally constitute the dominant group among invertebrates in these systems, exhibiting a wide distribution and tolerance to various levels of water quality. The changes in trophic features associated with the dominance of different major primary producers (macrophyte and phytoplankton) are reflected in the functioning of these ecosystems and likely in their phytophilous Chironomidae species richness and abundance. These were thus studied in a Brazilian shallow lake over a 11-year period characterized by both clear and turbid water conditions in relation to water quality and dominant macrophytes. The results revealed differences in Chironomidae composition but not in richness associated with clear and turbid waters. The Goeldichironomus genera predominated during all years and for different macrophyte types (freefloating, floating leaf, and submerged). We attribute the variability of Chironomidae assemblages to changes in macrophyte dominance and water trophic status, such as the concentration of nutrients and chlorophyll-a, during the 11-year period. Submerged macrophytes were associated with clear waters and harbored the highest diversity, which emphasized the importance of these environmental conditions for preserving the biodiversity of Chironomidae in shallow lakes.