Which variables influence the structure and abundance of aquatic herbivorous assemblages in small forested Patagonian wetlands?

Abstract

Herbivores in wetlands are key organisms that shape the structure and composition of wetland plant communities (algae and vascular plants). The detritus produced by herbivory contributes to nutrient cycling and provides important resources for other organisms in the ecosystem. Due to their importance we decided to survey a set of 12 seasonal wetlands located in Andean Patagonian forests. We registered biotic and abiotic variables of each wetland and the diversity and abundance of herbivores. We found two groups of wetlands: short and long hydroperiod. Despite this, the structure of the communities was not related with hydroperiod length as well as the abundance and species composition. In particular, the abundance of herbivores was explained by chlorophyll, pH, dissolved oxygen, among others. Their diversity and abundance was (in decreasing order): rotifers, copepods, cladocerans, caddisflies, and amphibians. Probably the species found in these wetlands are well adapted to different hydroperiod regimens and even in short hydroperiods can complete their life cycle. The results found here do not match with the model of hydroperiod gradient, however other variables not measured here such as diversity and abundance of aquatic plants or predation by invertebrates could impact the composition and abundance of herbivores in these wetlands.