Effects of landscape factors and hydroperiod on aquatic macroinvertebrates with different dispersal strategies in southern Brazil ponds

Abstract

Ponds represent discrete sites surrounded by a terrestrial landscape that is inhospitable for aquatic macroinvertebrates. Such ecosystems are appropriate for testing the influence of area, isolation, and correlated variables such as habitat diversity and hydroperiod, on aquatic macroinvertebrate communities. We tested three hypotheses in natural and non-impacted ponds located in a matrix of coastal dunes without human interference in southern Brazil: (1) area, habitat diversity, and hydroperiod increase the total macroinvertebrate richness and density, while isolation among ponds decreases the total macroinvertebrate richness and density; (2) the influence of environmental factors depends on the dispersal strategies of macroinvertebrates; and (3) macroinvertebrate composition is determined by the interaction of area, habitat diversity, hydroperiod, and isolation and differs among macroinvertebrates with different dispersal strategies. Fourteen ponds were sampled four times from October 2007 to August 2008 in the Lagoa do Peixe National Park coastline. Our results indicated that the pond area influenced only flying macroinvertebrate richness. The isolation and habitat diversity did not determine the richness, density, and composition of macroinvertebrates (total, flying, and non-flying). The richness, density, and composition of pond macroinvertebrates were determined mainly by hydroperiod. The mosaic created by the variation in pond hydroperiod would provide for a greater number of taxa with distinct dispersal capacities within the landscape. However, temporary ponds have disappeared at an alarming rate and there is a need to promote conservation of wetlands with different hydroperiods in southern Brazil.