Testing for Ecosystem Regime Change Inferred from the Autotrophic Pigment Signals in Lake Erie Sediments03/15/2016
Human activities (agricultural nutrient runoff, point source pollution and invasive species) coupled with local impacts of climate change have contributed to profound changes in aquatic ecosystem function in Lake Erie. Yuan et al., (2014) argued that evidence of these changes were preserved as an increasing trend in trace metal content in a core raised from the Sandusky subbasin of the central basin of Lake Erie, which signaled a shift in algal dominance toward Harmful Algae Bloom (HAB) forming cyanophytes. These algal changes have been bringing serious problems to local citizen life as well as economy, such as the HAB prevalence around the west basin of Lake Erie, which increased in the 1970s and again in the 1990s following two decades of success with nutrient abatement programs. While we have more present data for even predicting the occurrence of HAB, much less detail is known regarding the historical algal changes. Here we propose that this algal species change could be preserved in pigments signals recorded in sediments cores, and by analyzing and distinguishing pigments for several algae assemblages using Visible Derivative Spectroscopy (VDS), we can reconstruct the historical algal ecosystem change in Lake Erie. We seek to determine if the changes in the Western basin extended to the Central and Eastern Basin and to determine the natural cycles present in the lake prior to large-scale human impacts on the Lake.
Key words: Pigments, VDS, Algae Assemblages, Sediments, Ecosystems, Lake Erie.