BRS Adam Siepielski: The ecological dynamics of mass mortality events

host: Rachel Germain

Title talk: The ecological dynamics of mass mortality events

Abstract: Mass mortality events (MMEs) – rapid, large die-offs of animals – are increasingly recognized as emblematic disturbances of the Anthropocene. Despite their staggering scale, from billions of individuals lost to hundreds of millions of tons of dead biomass produced, we lack an understanding of their drivers, patterns, and consequences. In this seminar, I will discuss observational, theoretical and experimental studies that have addressed these issues. A global synthesis of over 700 MMEs in animal populations, shows that the magnitude of MMEs has intensified for many taxa, while declining or remaining stable in others. The most severe events were tied to multiple stressors, starvation, and disease, underscoring their links to global change. Theoretical models extend this picture by revealing that MMEs resemble, but are not equivalent to, resource pulses and disrupted trophic cascades. Instead, they produce distinct ecological signatures by simultaneously weakening top-down control and fueling bottom-up dynamics through resource release. Experimentally inducing predator MMEs in freshwater food webs demonstrated novel biomass dynamics that diverged from both simple predator removals and resource pulses, creating cryptic disturbances. Together, these findings establish MMEs as powerful yet underappreciated forces shaping ecosystems, challenging us to understand and anticipate their role in a rapidly changing world.

Short biography: University of Arkansas

I am interested in the causes, consequences, and maintenance of biological diversity. My research integrates studies on (1) how interactions between species evolve and persist, (2) what factors promote and constrain microevolutionary processes, (3) how interactions structure multispecies communities, and (4) which mechanisms promote the long-term maintenance of biological diversity. My work combines theoretical explorations of these themes with experimental and observational studies. Although I have used a variety of study systems, most of my lab's work is conducted using damselflies (a group of predatory aquatic insects closely related to dragonflies).