Adjacent environments contribute to the increase of zooplankton species in a neotropical river

Abstract

Aim:The distribution of the zooplankton community along the Paraná River and in adjacent environments (tributaries and lakes) was evaluated, as well as the contribution of the community present in these environments to the species composition of the Paraná River. It was expected that the ensemble of species found in the last sampling site of the Paraná River would represent the accumulation of species found in the upstream sites. Methods: The community was sampled at 25 sites, during 2013 and 2014, and the species richness and composition were determined. The similarity in the composition of the community between the environments was evaluated using cluster analysis, and the contribution of the species to the Paraná River was evaluated using nestedness analysis, using the NODF index. Results: Overall, 193 species were registered (116 rotifers, 48 cladocerans and 29 copepods), with the majority of species considered as rare (163 species). In general, the composition of the community in the river was dissimilar to the adjacent environments, although there was a relationship among communities. Rotifers presented broad distribution throughout the area. As expected, the zooplanktonic species presented a nested distribution, with the last river site representing a set of the species registered in the upstream sites. Conclusion: The results show the importance of the tributaries and lakes to the occurrence of species along the river. The distinct hydrological characteristics of the environments, as well as flow velocity, depth and connectivity, were responsible for the development of planktonic populations in the lakes that arrived in the main river through tributaries. With these results, we suggest the importance of the conservation of adjacent environments of the Paraná River for the maintenance of the zooplanktonic species in this system.

Cladocera distribution along an environmental gradient on the Cerrado-Amazon ecotone: a preliminary study

“…The species with the higher abundance were Acroperus tupinambá (Elmoor-Loureiro, 1997) with six individuals that were sampled from three sites, both from cropland and forest micro-basins. This species is known to be found both in large rivers as in their tributaries (Bomfim et al, 2017), there are even records of Acroperus tupinambá in lentic ecosystems (Debastiani-Júnior et al, 2015). We also sampled six individuals of Kisakiellus aweti, gathered from two sites, one cropland and one forest.…”