Taxonomic Attributes and Functional Feeding Groups (FFG) of Chironomidae to Assess the Ecological Status of Floodplain Lakes in the Trombetas and Tapajós River Basins, Brazilian Amazon

Abstract

Chironomidae is a group of insects widely distributed in aquatic ecosystems, where they are generally abundant and highly diverse, performing important ecosystem functions. These insects can serve as biomonitoring tools because they respond readily to environmental changes, especially those of human origin. In this study, we tested whether changes in land use and land cover (LULC), as well as environmental variables, would affect the functional feeding groups (FFG) and the Chironomidae community in floodplain lakes within the Trombetas and Tapajós river basins. Nine lakes were sampled in these areas. The collected material was sorted in the laboratory and mounted on semi-permanent slides for identification and classification into functional feeding groups. A total of 3536 individuals, distributed across 33 genera, were identified. Generally, environments characterised by non-forest natural formations, forested areas, and temperature were positively correlated with the Chironomidae community. Conversely, the variables electrical conductivity, urban area, and conductivity showed negative correlations with the community. Regarding the FFG, collector-gatherers were the most abundant, followed by predators, shredder-herbivores, and collector-filterers. When evaluating the influence of environmental variables and land use and cover on the FFG, we found that urban areas and non-forest natural formations negatively impacted predators and shredder-herbivores, while also increasing electrical conductivity. Additionally, low dissolved oxygen concentrations negatively affected collector-filterers, and collector-gatherers were negatively influenced by forested areas. Thus, our results corroborate the importance of environmental variables and changes in land use on the Chironomidae community, providing information that can contribute to the conservation of floodplain lakes, with biomonitoring of these lakes and information for public policies.