Life on the edge: Two dissimilar extreme events alter food webs through modification of top-down control

Abstract

Climate change is causing rapid, unexpected changes to ecosystems through alteration to environmental regimes, modification of species interactions, and increased frequency and magnitude of disturbances. Yet, how the type of disturbance affects food webs remains ambiguous. Long-term studies capturing ecosystem responses to extreme events are necessary to understand climate effects on species interactions and ecosystem resilience but remain rare. In the Gulf of Mexico, our 8-year study captured two disturbances that had contrasting effects on predator abundance and cascading effects on estuarine food webs. In 2017, Hurricane Harvey destroyed fishing infrastructure, fishing activity declined, and sportfish populations increased ~40% while intermediate trophic levels that sportfish prey upon declined ~50%. Then, in 2021, a fish kill caused by freezing temperatures during Winter Storm Uri reduced sportfish populations by ~60% and intermediate trophic levels increased by over 250%. Sportfish abundance affected the abundance and size of oyster reef mesopredators. Excluding fish predators significantly altered oyster reef community structure. These results demonstrate how extreme events shape communities and influence their resilience based on their effects on top predators. Moreover, top-down forces from sportfish are important in estuaries, persist through disturbances, and influence community resilience, highlighting the necessity of proper recreational fisheries management through extreme events.