Effects of land use on macroinvertebrate food webs in lowland riverine wetlands

ALTIERI, P.; RODRIGUES CAPÍTULO, A.; OCON, C.

Grand Rapids, Michigan

Congreso; Joint Aquatic Sciences Meeting 2022; 2022

American Fisheries Society

Food webs describe the structural organization of biota across trophic levels through their feeding links, and thereby crucial in understanding the stability and persistence of a given ecosystem. Within the aquatic biota, macroinvertebrates play an important role in wetlands functioning, so recognizing how their food-web structure responds to anthropogenic disturbance might be useful in management strategies. With this aim, we investigated macroinvertebrate food webs structure in pampean riverine wetlands of Argentina with different land uses. We selected two periurban wetlands with intensive agricultural land use and two with extensive livestock, considered references for the region. Through gut content analysis of 1176 organisms belonging to 59 taxa and available literature we estimated the trophic networks of each wetland and their parameters using the Cheddar package from the R software. Detritus was the main resource in gut contents of both land uses, highlighting the importance of this resource in lowland ecosystems. Agriculture riverine wetlands, characterized by higher nutrient concentration and lower macroinvertebrate richness and density, showed the simplest food webs represented by a smaller network size and lower number, density and complexity of links. This simplification was given by the loss of top predators sensitive to water quality degradation also reflected in the lowest resource: consumer ratio. In contrast, livestock wetlands showed higher proportion of top nodes and omnivores degree and a lower connectance due to the higher taxonomic richness. We found that the analysis of macroinvertebrate trophic relationships provide an overview of the environmental status of the riverine wetlands studied.