This free public video seminar is delivered as a large-screen presentation in room 202 at the UA Kachemak Bay campus in Homer; a short question and answer session is provided at the end of the presentation.

Friday, November 10, 2023, 4:00 pm

Understanding food web structure and stability in a changing world
Marie Gutgesell, USFS Pacific Northwest Research Station

Global change is threatening the stability and function of ecosystems by shifting underlying food web structures (i.e., rewiring food webs). The stability of ecosystems, in other words the ability of ecosystems to persist and thus maintain function in the face of environmental perturbations, is driven by food web structure. Food web structures are being rewired through alterations in spatial and temporal resource availability and consumer responses to changing conditions, such as climate change and landscape modification. Examining how changes in spatial and temporal resource availability and consumer responses shift in response to changing conditions can elucidate how they are altering food web structure, and ultimately influencing ecosystem stability and function. As an example, I identify and discuss a previously unconsidered aspect of subsidies, subsidy accessibility (ability of recipient species to access and thus forage on subsidies) that influence recipient food web dynamics. Using a combined bio-tracer approach I demonstrate how net-pen aquacultures can redistribute available resources by introducing a high-quality point-source subsidy, and how accessibility to this subsidy is a strong driver of recipient food web responses (trophic structure and biomass distribution). I then discuss how such food web concepts can be more broadly applied to understand human-centric subsistence food webs in Southeast Alaska.

Dr. Marie Gutgesell is a ORISE Postdoctoral Fellow with the USFS Pacific Northwest Research Station.