Zooplanktonic communities in a lentic environment of northern Corrientes Province, Argentina.

Introduction: Zooplanktonic communities can be found in a wide variety of freshwater bodies. Often, the main groups represented are rotifers, cladocerans, copepods, protozoa, and fish larvae. Other groups of animals may also occur and are collectively referred to as tychoplankton or neuston. Records on planktonic communities in aquatic environments of Corrientes, Argentina, are scarce so far. The objective of this research is to study the zooplankton communities in a lentic environment of the northern Corrientes to elucidate their diversity in this ecosystem. Methodology: Sampling was carried out in April 2024 (autumn) at the Totorá Lagoon (27° 22' S, 58° 30' W), San Cosme (Corrientes, Argentina). Water samples were taken with plastic buckets from the littoral zone. Floating and submerged macrophyte plants were extracted. In situ measurements of physicochemical water parameters were recorded. In vivo samples were observed by examining macrophyte leaves and roots using a stereoscopic binocular loupe and a compound microscope. Results: Oxygen levels were 7 mg/L, conductivity was 91 µS/cm, and pH was 7.6. The water temperature reached 27.1 °C, with 46 ppm of dissolved solids. A total of 14 phyla and 46 genera were identified. The most diverse groups wereciliophora, rotifers, and amoebozoa. Conclusion: These results demonstrate the presence of a remarkable diversity of species in the Totorá lagoon. Additionally, indicator species for specific environmental conditions were identified. This study represents the first record of planktonic communities in a lentic environment in Corrientes, Argentina, contributing to regional diversity. These findings could prove valuable for future research in the fields of ecology, biogeography, and biology.