The influence of shoreline availability on the density and richness of Chironomid larvae in Neotropical floodplain lakes

Henrique Ragonha, FlávioDaiane Pinha, GiseleGentilin Bilia, CamilaGuglielmetti da Silva, RenataPrandini Tramonte, RafaelMichiyo Takeda, Alice

The shoreline development index was created for temperate lakes. However, Neotropical lakes have different geological formations. For example, the difference between the littoral and limnetic zones in Neotropical lakes is not as sharp as those in temperate one, due to their low depths. Here, we proposed a modification of the shoreline development index for tropical lakes. We applied the modified index in 27 floodplain lakes of the Upper Paraná River. We found significant and positive relationships between the modified index and the density and richness of chironomids. These results suggest that the higher the availability of margins the higher the density and richness of larvae. The littoral zone of some lakes is complex, with submersed or emergent macrophytes, as well as branches and leaves that provide a wealth of habitats in this region. Therefore, the larger littoral zone seems to be the main factor structuring the chironomid community. Therefore, the modified index is an important statistical tool to indicate lakes in which chironomid richness is high due to the higher availability of littoral zone.Key words: Biodiversity. Invertebrates. Littoral zone. Margin region. Upper Paraná River. Zoobenthic community.