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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dPV a P X A Wdt
PhosphorusG
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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.
ij ij i i i i
dPV a P X A Wdt
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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Median 25%-75% Non-Outlier Range
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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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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.
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