Grant: Discovery Grants Program - Individual

Freshwater ecosystems (such as rivers, streams, and lakes) are necessary components for the functioning of many ecosystems and provide multiple ecosystem services to human society, including climate regulation, water quality regulation, and food stocking. These services depend on the biological components of the ecosystem that shape the short and long-term nutrient cycling and energy flow through their food webs. Freshwater food webs provide a convenient and effective tool to measure the health of an ecosystem since it can capture both the feeding interactions and the species in a network, allowing the measurement of ecosystem services and the whole community's resistances to disturbances. Some studies suggest a fundamental organization of food webs depending on the number of components, and others indicate that their structure and functioning depend to some extent on the habitat type, regional climate, biological composition, and anthropogenic stressors. Therefore, understanding how these factors regulate food web structure and functioning improves our capacity to predict and mitigate how future environmental changes will affect the ecosystem functions related to the food webs. In this program, I will merge a global synthesis approach with network theory and advanced statistical analyses to disentangle the relative importance of abiotic and biotic controls of food-web structure and functioning in freshwaters. Specifically, I will explore the regulatory effects of fishes on different freshwater ecosystems around the globe by analyzing how the food-webs composed by fishes and their trophic interactions change in face of environmental variation. Fish are well studied with abundant published information from diverse sources that allow the development of a global dataset on predator-prey interactions whick constitute the food webs. Fishes also display a myriad of ecological traits, are key members of food webs in a wide range of habitats and ecosystems, and provide fundamental ecosystem services. This program will address four objectives: 1) develop a global, collaboratively-designed dataset on trophic interactions of fish and their prey in freshwater ecosystems; 2) map knowledge pitfalls on the trophic interactions of freshwater fishes; 3) analyze the geophysical determinants (climate, ecosystem type, size, land use) of prey-predator networks of freshwater fish assemblages; and 4) quantify the relationship between taxonomic, functional, and phylogenetic diversity and food web properties. Together, these projects will create a novel framework to evaluate how food-web structure will vary in response to changes in environmental conditions and biodiversity composition.