Rotifers (Rotifera: Monogononta) Associated with Littoral Macrophyte Habitats in Flooded Neotropical Ponds: A Qualitative Study

Abstract

Rotifers represent an important component of freshwater zooplankton. The high richness of taxa, particularly in littoral macrophyte zones of water bodies in tropical and subtropical flood-prone areas, is a repeatedly reported fact. However, studies on the composition of periphytic rotifers in the Neotropics are reduced and almost non-existent in some regions. A qualitative study on rotifers (Monogononta) associated with littoral aquatic vegetation and their seasonal variation was carried out in three flood-prone ponds in the “Esteros de Camaguán Fauna Reserve” in the Venezuelan plains. For the selection of the collection sites, the two-stage stratified method with proportional affixation was used. Samples of macrophytes and the water associated with them were taken in littoral zones. The percentages of occurrence and numerical frequency were calculated for each rotifer taxa. The faunal similarities and correlations within and between ponds in the same and different climatic seasons were estimated using the Jaccard and Spearman coefficients (α = 0.05), respectively. In total, 102 rotifer taxa associated with 11 species of aquatic macrophytes were identified. The genus Taphrocampa with two taxa plus ten other taxa, are new records for Venezuela and one of them for South America. The taxocenosis and the geographic distribution of the reported taxa reflect a typical composition of the littoral zones of tropical regions. The total richness of both planktonic associated with aquatic vegetation and periphytic assemblages were similar. The highest richness of rotifer taxa coincided with the rainy season and the lowest with the early rainy season. The rotifer fauna presented low similarity values within and between ponds according to seasonality and, with some exceptions, between planktonic and periphytic environments. The importance of sampling periphytic rotifers and the influence of the flood cycle, and the degree of macrophyte development in the structuring of periphytic rotifer communities, were confirmed.