Zooplankton trait variation along environmental gradients in shallow lakes from the Lower Paraná River floodplain (Argentina)

CHAPARRO, GRISELDA; GAYOL, MAIRA PATRICIA; MORANDEIRA, NATALIA SOLEDAD; KANDUS, PATRICIA; O´FARRELL, INÉS

Natal

Conferencia; 10th International Shallow Lakes Conference; 2021

Universidade Federal do Rio Grande do Norte

The floodplain of the Lower Paraná River is a mosaic of wetlands that includes numerous shallow lakes and hosts an exceptional high biodiversity. The local environmental conditions of the shallow lakes change constantly according to the discharge regime of the river, thus constituting a major challenge in understanding the distribution of biodiversity. We studied zooplankton (rotifers) communities in shallow lakes that differed in their connectivity to watercourses (connected/isolated) during different hydrological conditions (potamophase and limnophase). We used a trait-based approach to explore changes in community composition and functional diversity along environmental gradients in each phase and between them. Our results revealed a gradient of environmental conditions associated with the connectivity, which persisted at limnophase and potamophase conditions. Connected lakes presented high turbidity, suspended solid and nutrient concentrations, while disconnected lakes showed opposed features and could develop either low or high phytoplanktonic chlorophyll a concentration (representing clear or organic turbid conditions, respectively). The environmental heterogeneity of the lakes was similar between hydrological phases and connectivity of the lakes. Our first results regarding the zooplankton community indicate that functional diversity tended to increase during limnophase and in isolated lakes, and that individual community trait values were similar between phases and lakes connectivity. The community traitenvironment relationship was overall weak and stronger during limnophase, and turbidity resulted in the most important variable in both conditions. Our results show that the connectivity of the shallow lakes determines their local environmental conditions and seems to have a weak influence on rotifers trait composition and functional diversity.