Spatial asynchrony in the western basin of Lake Erie derived from high frequency buoy data

Background/Question/Methods

The western basin of Lake Erie experiences recurring, dense, and spatially expansive harmful algal blooms (HABs), which can sometimes be so severe that intakes for municipal drinking water systems must be temporarily shut down. Funded by an Alliance grant from Canada’s Natural Sciences and Engineering Research Council, our goal is to develop an early-warning system for HABs in Lake Erie using real-time high frequency sensor data collected from a network of monitoring buoys. Our first objective is to identify any spatial variation in the underlying processes that govern HAB formation and movement to refine the placement of monitoring buoys for this early-warning system. The western basin of Lake Erie receives water from both the Detroit and Maumee Rivers, creating a complex system of two hydrochemically distinct inflows with variable circulation patterns. In 2021, a network of seven monitoring buoys were deployed in the western basin that captured these distinct water circulation patterns, major tributary inputs, and nearshore/offshore environments. We used mean Pearson correlation and correlation matrices to tabulate spatial synchrony of surface and bottom water chlorophyll, temperature, and dissolved oxygen, as well as thermal stratification and water circulation indices, collected from the buoy array.

Results/Conclusions

Our preliminary analysis suggests that spatial asynchrony is present. Asynchrony in dissolved oxygen was present in epilimnion and hypolimnion, and in chlorophyll in the epilimnion. In contrast, we found that water temperature was synchronous. This asynchrony implies that an effective early-warning system will require data collected from many locations. Additionally, asynchrony indicates that HAB formation in Lake Erie is largely driven by internal factors and dynamics.