EAGER: Stage-structured predation between fish and aquatic insects

University Of South Dakota Main Campus, Vermillion SD

Investigators

Abstract

A fundamental challenge in ecology is to predict how extinction of some species will impact other species that are left behind. It's complicated because all species interact with a large number of other species. They eat or are eaten by those species, creating what are called "food webs". Practically all studies of food webs ignore the simple fact that interactions among species are likely to change as individuals grow up. For example, a butterfly eats different things as a caterpillar than as an adult. Likewise, different animals are likely to eat it as a caterpillar than as an adult. Another problem with past studies is that food webs in one habitat are treated as totally separate from those a nearby habitat. The simple fact that animals often move between habitats is typically ignored. This project overcomes both of these problems with past studies. Researchers will test how fish in streams not only affect their prey under water but also how those prey affect animals above water. Students will help collect data, learning cutting-edge ecological techniques. All participants will share their knowledge about food webs with school children and the general public. Results from this project will be important for managing freshwater resources and preserving their benefits for all. More generally, this project is in the national interest because humans rely on properly functioning food webs for recreation, food, and water quality. Through field surveys and manipulative experiments, this project will examine stage-structured interactions between fish and their insect prey, and the consequences of those interactions for linked aquatic-terrestrial ecosystems. Aquatic insects develop as larvae on the bottom of streams and lakes. They then metamorphose and emerge as winged adults in the terrestrial ecosystem. After emerging from the water, aquatic insects become common prey for terrestrial predators. As a result, fish predation on aquatic insects can affect terrestrial food webs. However, prey life stages vary dramatically in ecological traits, which means they are differentially susceptible to predation by fishes. This combination of cross-ecosystem movement by prey and stage-structured predation means that the effects of fish predation can not only extend beyond ecosystems, but could even be stronger in the terrestrial ecosystem than in the aquatic ecosystem. Such effects of predators would not be predicted based on current species-centric food web approaches, making this a somewhat risky project with high potential for changing how food webs are viewed. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.