Presentation on theme: "Martin T. Auer and Lisa M. Tomlinson Michigan Technological University Scott N. Higgins and Sairah Y. Malkin University of Waterloo E. Todd Howell Ontario."— Presentation transcript:
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 Image by Jason Oyadomari, available at http://www.keweenawalgae.mtu.edu/ALGAL_PAGES/ulvophyceae.htmhttp://www.keweenawalgae.mtu.edu/ALGAL_PAGES/ulvophyceae.htm Great Lakes Cladophora Into the 21 st Century: Same Alga – Different Ecosystem
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.htmhttp://www.mlswa.org/UnderWaterPlantGuide/cladophora.htm
Cladophora in the Great Lakes Image from Taft and Kishler (1973) Windrows of sloughed Cladophora were known from Lake Erie in the 19 th century.
Cladophora in the Great Lakes Nuisance growth of Cladophora was prevalent in Lake Ontario by the late 1950s.
Cladophora in the Great Lakes Problems were also encountered in Lake Michigan.
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
Cladophora in the Great Lakes Awakening “Cladophora in the Great Lakes” H. Shear and D.E. Konasewich Great Lakes Research Advisory Board International Joint Commission, 1975 International Joint Commission “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
Cladophora in the Great Lakes Research Initiatives monitoringexperimentationmodelingmanagement
Models: Great Friend or Greatest Friend? Does modeling generate solutions or just more questions of interest to modelers? Linking monitoring and experimentation by providing a means for testing our understanding of factors mediating Cladophora growth dynamics. Phosphorus Growth MODEL
Models: Great Friend or Greatest Friend? Does modeling generate solutions or just more questions of interest to modelers? Linking monitoring and management by providing a means of evaluating the potential impact of phosphorus control strategies. MODEL
Cladophora in the Great Lakes 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 Management Applications BEFORE P-removal AFTER P-removal Shoreline outfall length
Cladophora in the Great Lakes Image from http://www.coam.org.uk/Events/may.htmhttp://www.coam.org.uk/Events/may.htm The “Dark Age of Cladophora” – 1985-2005
Why Cladophora? Why now? Rock Point Provincial Park, Lake Erie. Image by Scott Higgins. Public perception of Great Lakes water quality is based, in large part, on the experience at the land-water interface. Bradford Beach, Lake Michigan Image provided by Harvey Bootsma. Coronation Beach, Lake Ontario. Image by Sairah Malkin
Growth Mediating Condition: Phosphorus Changes in phosphorus change standing crop but have a lesser impact on depth of colonization.
Response to P Loading Reductions Lake Ontario Model output generally consistent with the observations of Painter and Kamaitis (1985).
Not Your Grandmother’s Ecosystem Image by Sairah Malkin
What changed? Data for Milwaukee Harbor monitoring site provided by Harvey Bootsma. 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.
Growth Mediating Condition: Light Changes in the underwater light environment impact the depth of colonization. increasing transparency
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/http://www.glwi.uwm.edu/research/aquaticecology/cladophora/ Courtesy of John Janssen
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.
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.
And if that’s not enough … Image from http://www.glwi.uwm.edu/research/aquaticecology/cladophora/http://www.glwi.uwm.edu/research/aquaticecology/cladophora/ Hecky et al. (2004) describe the role of zebra mussels as ‘ecosystem engineers’, creating a nearshore phosphorus shunt that can stimulate Cladophora growth.
So … what to do? Images from http://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb= andhttp://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb= http://focus.nigz.nl/index.cfm?act=info.summary&varrub=7 In the 1960s In the 1980s In the Dark Age of Cladophora
20 Years of Footprints in the Cladophora Image at right courtesy of Harvey Bootsma 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
Reductions in nuisance growth of Cladophora will require reductions in P loadings to the nearshore. 1.Institute monitoring programs. 2.Research nearshore P dynamics. 3.Upgrade models to reflect ecosystem changes. 4.Apply models to test management strategies. Cladophora: Recommendations Image from http://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb=http://www.azote.se/index.asp?sa=30&str=Camilla%20Bollner&t=71&b=1&lb= This will require an Integrated Approach