The Daily Bulletin Archive

Please join us for the seminar "Long-Term Change in the Great Lakes Lower Food Web: The Importance of Deep Chlorophyll Maxima," presented by Annie Scofield, postdoctoral research associate in the Department of Forestry and Natural Resources at Purdue University, on Monday, November 5, from 3:00 to 4:15 p.m. in Bulger Communication Center 424. Dr. Scofield's talk is part of the Biology-Great Lakes Center Seminar Series.

Abstract
The Laurentian Great Lakes have undergone oligotrophication in recent decades, leading to changes in the lower food web. Epilimnetic production has declined in some lakes, but increased production in deep chlorophyll maxima (DCM) may partially compensate for these losses. For example, the DCM in Lake Ontario now has chlorophyll concentrations two to three times that of the epilimnion, and it is a productive layer during summer stratification. Understanding the dynamics of DCM is thus essential to assess the bottom-up effects of changing lake productivity. For instance, the vertical redistribution of phytoplankton may cause selection pressure toward cold-adapted zooplankton that can effectively utilize the DCM as a food resource. Along with changes to lake productivity, zooplankton communities in the Great Lakes have shifted toward dominance by deeper-dwelling species, such as calanoid copepods. In this research, I explore the potential bottom-up food web effects of DCM dynamics using evidence from long-term monitoring data, zooplankton feeding experiments, and stable isotopes.