Benthic invertebrates nestedness in flood and drought periods in a Neotropical floodplain: looking for the richest environments

Abstract

Aim Floodplains are among the most biologically diverse systems in the world, where hydrological regime is recognized as crucial to structure aquatic communities. We predicted that i) structure of benthic metacommunity is nested in the drought and random in the flood season in a Neotropical floodplain. We expected to find ii) environmental homogenization during the flood season which may disrupt the nested pattern. Moreover, we identified habitats of high taxa richness of benthic invertebrates and characterized them by habitat type and fluvial systems. Methods We sampled benthic invertebrates from 36 habitats in the Upper Paraná River floodplain. We tested nestedness using NODF index and evaluated the environmental variability using the multivariate homogeneity of group dispersions (PERMDISP), separately for flood and drought periods. Results The environmental variability was lower during the flood. We found a nested distribution among benthic invertebrates in both flood and drought periods. The highest species richness values were recorded in small and unconnected lakes from Paraná fluvial system and some rivers and secondary channels, independent of the fluvial system. Chironomidae, Oligochaeta and Ostracoda were the most frequent taxa and were recorded in all habitats. Conclusion The nested distribution of benthic invertebrates is a consistent pattern for this metacommunity because its distribution was not disrupted by floods that homogenize limnological conditions and increase the connectivity among habitats. We also found that habitats with high taxa richness were both lotic and lentic in the three fluvial systems. Our findings emphasize that different habitats in different subsystems sustains the richness of the benthic invertebrates metacommunity in the Upper Paraná River floodplain over time.

Nestedness of stream insects in Subtropical region: importance of inter-annual temporal scale

“…We detach that in the year were precipitation were the lowest, the richness were high, this precipitation pattern probably homogenize the habitat increasing species co-existence (Restello et al, 2014). Pinha et al (2016) registered nestedness on Chironomidae assemblage during the flood period justifying the result saying that inundations can homogenize limnological conditions.…”

The drift effect on nestedness of ephemeroptera, trichoptera and plecoptera orders in the Xingu River

“…However, if the previous line has higher number of genera than the posterior one, the index uses the common occurrence in both lines to generated the value of the NODF. This calculation is performed for both rows and columns and at the end the overall mean will be achieved resulting in the general NODF (Milesi & Melo 2014, Pinha et al 2016.…”

Differences in environmental heterogeneity promote the nestedness of Chironomidae metacommunity in Neotropical floodplain lakes

“…According to Pinha et al (2016), periods with high environmental heterogeneity (i.e., drought periods represented by September) can support more taxa in relation to sites or periods with low environmental heterogeneity (i.e., flood periods represented by March) and facilitate the formation of a nested distribution.…”