Restauração de um lago temperado: efeitos sobre a diversidade taxonômica e funcional de protistas ciliados.

Abstract

Aquatic ecosystem restoration has proven to be an essential strategy for recovering biodiversity and ecological functionality in degraded environments. Thompson Lake (Illinois, USA) was previously used as agricultural land for 80 years before being restored through vegetation removal followed by reflooding. This study evaluated the effects of the restoration process on the taxonomic and functional diversity of planktonic ciliate protists between 2011 and 2016. Samples were collected from different points in the lake, considering both biotic data (composition, richness, and abundance of morphospecies) and abiotic parameters (physicochemical characteristics of the water), as well as functional traits such as morphology, feeding habits, and defense mechanisms. A total of 71 ciliate morphospecies were identified, with Oligotrichida, Gymnostomatida, and Hymenostomata being the dominant groups. Temporal analyses revealed significant variations in abiotic conditions and in the taxonomic and functional attributes of the community. Species richness gradually increased over the study period, while abundance was higher in the initial years of restoration. Species turnover was the main driver of changes in taxonomic and functional composition, suggesting an ecological succession process. Functional diversity, particularly divergence (FDiv) and evenness (FEve) indices, remained high, although functional richness (FRic) showed temporal fluctuations. The results indicate that its restoring the lake to original state promoted the structural and functional reorganization of the ciliate protist community, reflecting progress in the lake's ecological recovery. These findings reinforce the potential of ciliates as environmental bioindicators and highlight the importance of integrating taxonomic and functional diversity approaches in monitoring ecosystems under restoration.