On July 20th 2016, graduate student Anthony Weinke successfully defended his Master’s thesis titled “Green and Choking: Exploring the Dynamics of Seasonal Productivity and Hypoxia in a Great Lakes Area of Concern and Habitat Blueprint Estuary Using Time-Series Measurements”. His thesis committee members included GVSU faculty members Bopaiah Biddanda, Mark Luttenton, Richard Rediske, Carl Ruetz, and James McNair, as well as Steven Ruberg from NOAA’s Great Lakes Environmental Research Laboratory.
In his thesis, Anthony reports that episodic wind events and hypoxia have many effects on the Muskegon Lake ecosystem. The low wind speeds and heat of the summer causes the lake to stratify, which allows bacteria to draw down dissolved oxygen in the bottom waters to low, hypoxic, levels. Especially strong wind events have the ability to relieve hypoxia in the shallow areas of the lake; however, hypoxia persists in the deep locations. In this study, hypoxia was found to lead to release of bioavailable nutrients such as soluble reactive phosphorus from the lake sediment, which algae need to form blooms. Once released into the bottom waters, nutrients can be brought to the surface via episodic wind events. Additionally, fish need dissolved oxygen to “breathe”, but the low dissolved oxygen concentrations in the bottom waters forces most of the fish to leave the lake bottom during the summer. Indeed, Anthony found a strong inverse correlation between fish caught in bottom waters (both abundance and diversity) and the level of hypoxia.
After formally completing his thesis submission to the Graduate School, Anthony plans to pursue a career in marine fisheries conservation.