TEMPORAL AND SPATIAL VARIATION OF ALGAL BLOOMS IN OLD WOMAN CREEK NATIONAL ESTUARY OF LAKE ERIE DURING THE SUMMER OF 2016, USING REFLECTANCE SPECTROSCOPY

Algal blooms have plagued the western basin of Lake Erie for several years. Old Woman Creek (OWC) is an estuary found along the western basin of Lake Erie. Water samples were collected from four sampling sites within the estuary: VC, WM, OL, and MO when the mouth bar controlling outflow from OWC to Lake Erie, was closed. Water (250 ml) was filtered through 0.4 μm GF/F filters by vacuum filtration. The reflectance of oven-dried filter was measured using a Minolta spectrophometer. Total suspend solids (TSS) were calculated by weighing the filters prior to filtration, then after oven drying. Varimax-rotated, Principal Component analysis of center-weighted derivatives of reflectance derived three components explaining 95% variance in the data. Comparison of these components with known minerals and pigments resulted in the following combinations: VPC 1 is diatoms, illite, kaolinite, and dinoflagellates, VPC 2 is cyanobacteria pigments, and VPC 3 is illite, peridinin, cyanobacteria, allophycocyanin, and echinenone. While all three components have some aspect of sediment in this turbid water system, the leading component represents a diatom/dinoflagellate community, component 2 is cyanobacterial community 1, and component 3 is cyano/dinoflagellate contrast. These components were compared against other variables that could provide insights on the nature of the algal blooms including: dissolved oxygen (DO), wind speed, TSS, turbidity, and conductivity. Wind speed showed a positive correlation at WM with the second cyanobacterial component. Due to MO being in the lower part of the estuary, sediments accumulate near the closed mouth bar. Wind speed correlates with diatom/dinoflagellate component at MO with a lag time of one day, suggesting that wind mixing was resuspending sediment with nutrients, which enabled subsequent growth. TSS shows a significant negative correlation with the diatom/dinoflagellate component at sites VC and OL (r=0.64, α=0.05 and r=0.84, α=0.05 respectively), suggesting turbidity inhibits growth. TSS shows a strong correlation at MO with the second cyanobacterial component (r=0.90, α=0.001). DO correlates positively with the second cyanobacterial component with a lag time of one day at all sites, possibly due to contribution of photosynthetic productivity.