Piscivorous fishes as connectors in ecological networks of a neotropical floodplain

BORZONE MAS, DALMIRO; SCARABOTTI, PABLO A.; ARIM, MATIAS

Dublin

Simposio; SEFS 12 Symposium for European Freshwater Sciences; 2021

The compartmentalization of interactions in the ecological networks and the role of species connecting these compartments determine the stability and dynamic of the ecosystems. Species traits as body size or those related to environmental and trophic niche may determine species role in different ecological networks as food web and occurrence networks. In this work, we analyzed the topological roles of 16 piscivorous fishes of the Middle Paraná River in occurrence networks and food webs and the traits that determine them along different hydrologic and climatic conditions. We sampled 20 aquatic environments, during 20 samplings over five years analyzing the spatial distribution and trophic interactions of 3048 individuals. A modular structure was observed in both networks persistent over time, despite the species change their roles in the different hydro-seasonal situations. The body size and ecomorphology were determinants for the topological role in the occurrence networks and the food webs. Large-bodied species connected the modules of the food web, whereas the small-sized species connected spatial aggregations of occurrence networks. Morphologies associated with swimming and predation behaviours were consistently related to the connector role in both networks. Among the species with the highest degree of connection, there was a positive correlation in the intermodular connection in both networks, ustaining the idea of the large mobile predator as network integrators. The relationship between species traits and topological roles supports the idea of a no-neutral assembly of ecological networks, and the dynamic role of species may foster the stable modular structure along the time.