Martin T. Auer and Lisa M. Tomlinson Michigan Technological UniversityScott N. Higgins and Sairah Y. Malkin University of WaterlooE. Todd Howell Ontario Ministry of the EnvironmentHarvey A. Bootsma University of Wisconsin – Milwaukee

Image by Jason Oyadomari, available at http://www.keweenawalgae.mtu.edu/ALGAL_PAGES/ulvophyceae.htm

Great Lakes CladophoraInto the 21st 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.htm

Cladophora in the Great Lakes

Image from Taft and Kishler (1973)

Windrows of sloughed Cladophora were known from Lake Erie in the 19th 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 BoardInternational Joint Commission, 1975

InternationalJoint

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

monitoringmonitoringexperimentexperimentationationmodelingmodelingmanagememanagementnt

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 testingour understanding of factors mediating Cladophora growth dynamics.

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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.

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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

outfalllength

Cladophora in the Great Lakes

Image from http://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 MichiganImage 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.

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Response to P Loading Reductions

Lake Ontario

Model output generally consistent with the observations of Painter and Kamaitis (1985).

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Not Your Grandmother’s Ecosystem

Image by Sairah Malkin

What changed?

Annual Secchi Disk Data For Outer Harbor Site 13

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Data for Milwaukee Harbor monitoring site provided by Harvey Bootsma.

Lake MichiganMilwaukee 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.

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Pre- and Post-Dreissenid Transparency

19867m depth, off Chicago

200113m depth, off Milwaukee

Images from 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.

Effect of Extinction Coefficient

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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.

Combined Effect

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And if that’s not enough …

Image from 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= and

http://focus.nigz.nl/index.cfm?act=info.summary&varrub=7

In the 1960sIn the 1980sIn the Dark Age of Cladophora

20 Years of Footprints in the Cladophora

Image at right courtesy of Harvey Bootsma

20051985The 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=

This will require an Integrated Approach