A influência de variáveis ambientais na comunidade zooplanctônica em duas zonas climáticas distintas

Abstract

Climate change can directly impact aquatic ecosystems, promoting changes in biological communities, especially zooplankton. Therefore, the purpose of the present study was to evaluate the variation of species richness and total zooplankton density over time in water bodies of two regions with different climates, and the role of environmental variables in this variation. The gathering of zooplankton and environmental variables were carried out between 2011 and 2017, in the Gargalheiras reservoir, located in the state of Rio Grande do Norte (tropical region) and in Lagoa das Garças, located in the of state Paraná (subtropical region). Zooplankton was identified and quantified in the laboratory. A PCA was carried out to characterize the two regions through environmental variables over time, with chlorophyll-a and total phosphorus being the main contributors to the separation of environments. The temporal variation of zooplankton richness and density was evaluated using a linear regression and the effect of environmental variables on these indices was verified through a multiple regression analysis. During the study period, the tropical region presented a higher total density of zooplankton and the subtropical region a higher species richness. Multiple regression analysis indicate a negative effect of chlorophyll-a and transparency on zooplankton density for tropical region. While in subtropical region, density was positively influenced by temperature and pH and negatively by chlorophyll-a. Regarding richness, there was no effect of the variables on this attribute in the tropical region, however, the variation of this attribute for subtropical region was explained negatively by chlorophyll-a and dissolved oxygen. The negative relationship between zooplankton indices and chlorophyll-a concentration and water transparency can be explained by the increase in eutrophication in continental water bodies due to changes in precipitation and temperature patterns, as well as anthropic actions.