Martin T. Auer and Lisa M. Tomlinson Michigan Technological University

1. Image by Jason Oyadomari, available at http://www.keweenawalgae.mtu.edu/ALGAL_PAGES/ulvophyceae.htm Great Lakes Cladophora Into the 21st Century: Same Alga – Different Ecosystem Martin T. Auer and Lisa M. Tomlinson Michigan Technological University Scott N. Higgins and Sairah Y. Malkin University of Waterloo E. Todd Howell Ontario Ministry of the Environment Harvey A. Bootsma University of Wisconsin – Milwaukee

2. Cladophora in the Great Lakes • Cladophora is a filamentous green alga, first identified in Lake Erie in 1848. Image at left from http://www.mlswa.org/UnderWaterPlantGuide/cladophora.htm

3. Cladophora in the Great Lakes • Windrows of sloughed Cladophora were known from Lake Erie in the 19th century. Image from Taft and Kishler (1973)

4. Cladophora in the Great Lakes • Nuisance growth of Cladophora was prevalent in Lake Ontario by the late 1950s.

5. Cladophora in the Great Lakes • Problems were also encountered in Lake Michigan.

6. Cladophora in the Great Lakes • Great Lakes Water Quality Agreement Five of the six goals set forth under Annex 3, Control of Phosphorus, relate to nuisance algal growth. Image by Richard Lorenz

7. Cladophora in the Great Lakes “Cladophora in the Great Lakes” H. Shear and D.E. Konasewich Great Lakes Research Advisory Board International Joint Commission, 1975 • Awakening “I wish I could inundate you with pictures … pictures of bikini-clad young lovelies standing waste deep in certain waters … ten pounds of green stringy material festooning their otherwise delightful limbs … the only stimulus needed to complete your abhorrence of the situation would be the accompanying flies and pig-pen odor which go hand-in-hand with rotting protein. Gentlemen, Cladophora is a big problem. Carlos M. Fetterolf, Jr. Executive Secretary, Great Lakes Fisheries Commission International Joint Commission

8. Cladophora in the Great Lakes • Research Initiatives monitoring experimentation modeling management

9. Growth Phosphorus Models: Great Friend or Greatest Friend? Linking monitoring and experimentation by providing a means for testing our understanding of factors mediating Cladophora growth dynamics. Does modeling generate solutions or just more questions of interest to modelers? MODEL

10. Models: Great Friend or Greatest Friend? Linking monitoring and management by providing a means of evaluating the potential impact of phosphorus control strategies. Does modeling generate solutions or just more questions of interest to modelers? MODEL

11. BEFORE P-removal outfall length AFTER P-removal Shoreline Cladophora in the Great Lakes • Management Applications Nuisance growth of Cladophora, defined as a standing crop of >50 gDW∙m-2, can be prevented if soluble reactive phosphorus concentrations are kept below 2 μgP∙L-1. Canale and Auer 1982

12. Cladophora in the Great Lakes • The “Dark Age of Cladophora” – 1985-2005 Image from http://www.coam.org.uk/Events/may.htm

13. Why Cladophora? Why now? Public perception of Great Lakes water quality is based, in large part, on the experience at the land-water interface. Coronation Beach, Lake Ontario. Image by Sairah Malkin Bradford Beach, Lake Michigan Image provided by Harvey Bootsma. Rock Point Provincial Park, Lake Erie. Image by Scott Higgins.

14. Growth Mediating Condition:Phosphorus Changes in phosphorus change standing crop but have a lesser impact on depth of colonization.

15. Response to P Loading Reductions Lake Ontario Model output generally consistent with the observations of Painter and Kamaitis (1985).

16. Not Your Grandmother’s Ecosystem Image by Sairah Malkin

17. What changed? Lake Michigan Milwaukee Harbor The depth of the photic zone, i.e. the 1% light level, has increased by 6m, on average, in Lakes Erie, Michigan and Ontario. Data for Milwaukee Harbor monitoring site provided by Harvey Bootsma.

18. Growth Mediating Condition:Light increasing transparency Changes in the underwater light environment impact the depth of colonization.

19. Pre- and Post-Dreissenid Transparency 1986 7m depth, off Chicago 2001 13m depth, off Milwaukee Images from http://www.glwi.uwm.edu/research/aquaticecology/cladophora/ Courtesy of John Janssen

20. Response to Increased Transparency The increase in growth potential is driven by an increased depth of colonization, with Cladophora occupying solid substrate at depths 3.0 – 4.5 m deeper than in the pre-dreissenid period.

21. Combined Response The net effect is that gains achieved through reductions in phosphorus loading have been offset by dreissenid-driven improvements in the underwater light environment and attendant colonization of new habitat by Cladophora.

22. And if that’s not enough … Hecky et al. (2004) describe the role of zebra mussels as ‘ecosystem engineers’, creating a nearshore phosphorus shunt that can stimulate Cladophora growth. Image from http://www.glwi.uwm.edu/research/aquaticecology/cladophora/

23. In the Dark Age of Cladophora In the 1980s In the 1960s So … what to do? Images from http://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb=and http://focus.nigz.nl/index.cfm?act=info.summary&varrub=7

24. 20 Years of Footprints in the Cladophora 2005 1985 The failure to maintain the biological integrity of the nearshore areas of four of the five Great Lakes needs to be addressed. Review Working Group [D] Draft Final Report, September 2006 Image at right courtesy of Harvey Bootsma

25. Cladophora: Recommendations • Reductions in nuisance growth of Cladophora will require reductions in P loadings to the nearshore. • Institute monitoring programs. • Research nearshore P dynamics. • Upgrade models to reflect ecosystem changes. • Apply models to test management strategies. This will require an Integrated Approach Image from http://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb=