Synopsis and insight into the harmful algal blooms that hit Grand Lake St. Marys in 2010.

1. William E. Lynch Jr. Aquatic Ecosystem Management Specialist Ohio State University Extension Program

2. Winter (ice – 39 F) Low biomasses of all types Early Spring (40 – 50 F) Diatom bloom Spring – Early Summer (50 – 72 F) Green algae bloom P Limited Systems N Limited Systems Mid - Late Summer (72 – 80+ F) Green algae Mid - Late Summer (72 – 80+ F) Cyanobacteria bloom Fall (80+ – 50 F) Green algae or cyanobacteria early Diatom bloom late

3. Large Lakes and Reservoirs 2009

4. Large Lakes and Reservoirs 2010 2009

5. Those Where Microcystin > 20ppb ( WHO Recreational Standard ) 2010: Microcystin > 20 ppb Note: Nearly all were less than 1 ppb; WHO’s drinking water standard 2010

7. Ponds & Small Lakes Suspected based on provided description Confirmed based on site visit or provided sample

12. 0 25 30 20 15 10 5 Summer N:P Ratio Cyanobacteria Abundance (%) of Algal Community 0 25 50 75 100 oligotrophic mesotrophic eutrophic hypereutrophic Adapted from: United Nations Environment Program Div. Of Technology, Industry, & Economics

13. N:P Ratio 4/15 5/10 6/9 acceptable desirable No HAB’s

14. N:P Ratio – Grand Lake St. Mary's Example N:P Ratio 4/15 5/10 6/9 acceptable desirable 7/14 No HAB’s *** Toxins first detected in late June

15. N:P Ratio – Grand Lake St. Mary's Example N:P Ratio 4/15 5/10 6/9 acceptable desirable 7/14 No HAB’s *** Toxins first detected in late June 8/19 9/15 10/7 HAB’s Widespread

16. Grand Lake St. Mary's 2010 P Levels Phosphorus 4/15 5/10 6/9 Target (<34 ppb) 7/14 8/19 9/15 10/7 ppb

17. Grand Lake St. Mary's 2010 N Levels Nitrogen 4/15 5/10 6/9 Target (<930 ppb) 7/14 8/19 9/15 10/7 ppb