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 Image at left from

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

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 of 1972 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 “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

Project Objectives identify growth-mediating environmental factors develop algorithms describing those relationships incorporate algorithms in a mechanistic model test model in a demonstration program apply model to determine limiting nutrient levels

Study Site Harbor Beach, Lake Huron regional nearshore has little or no Cladophora severe local impact due to P point source Lekan and Coney 1982

Local Conditions point source of nutrients

Local Conditions gradients in light, phosphorus and biomass Distance From Nutrient Source (km) Biomass (gDWm -2 ) Dissolved P (  gPL -1 ) Stored P (%DW) 145

The Model mass balance approach three state variables - dissolved phosphorus, P - stored phosphorus, Q - Cladophora biomass, X Rock Creek Spring Creek WWTP Effluent

Conceptual Framework Dissolved Phosphorus Stored Phosphorus Cladophora Biomass Loading Exchange Uptake Saturation Feedback Loss to Sloughing Loss to Respiration Carrying Capacity Feedback Light and Temperature Mediation

Modeling P (dissolved P) source/sink terms: - loading, W - uptake by Cladophora,  X A - mass transport, a ij

Modeling Q (stored P) source/sink terms: - gain through uptake,  - loss to growth partitioning,  Q Stored Phosphorus Uptake Saturation Feedback Demand for Growth

Modeling  (P uptake) uptake as mediated by: - dissolved P - stored P - temperature,  P uptake (% P per day) Q = 0.12% Q = 0.23% Dissolved Phosphorus (  gP  L -1 ) Maximum P uptake (% P  d -1 ) Stored Phosphorus (%P)  max * = 4.5 %Pd -1 K q = 0.07 %P 4.0

Modeling X (biomass) source/sink terms: - gain through growth,  - loss to respiration, R - loss to sloughing, L

Modeling  (growth) growth mediating functions: - light and temperature, f (I,T) - stored P, f (Q) - carrying capacity, f (X)

Modeling  (growth) growth mediating functions: - light and temperature, f (I,T) - stored P, f (Q) - carrying capacity, f (X)

Modeling  (growth) growth mediating functions: - light and temperature, f (I,T) - stored P, f (Q) - carrying capacity, f (X) Net Specific Growth Rate (d -1 ) Stored Phosphorus (%P) 0.8

Modeling  (growth) growth mediating functions: - light and temperature, f (I,T) - stored P, f (Q) - carrying capacity, f (X)

Modeling R (respiration) basal (dark) and light-enhanced - basal, f (,T) - light-enhanced, f (I,T)

Modeling L (sloughing) varies with wind and biomass, f (w,X) Biomass (gDWm -2 ) M J J A S O 400 = wind event

Demonstration Program (nutrient management) supporting model calibration and verification - calibration: conditions prior to treatment - verification: conditions following treatment

Model Calibration and Verification (147) Phosphorus (µgP∙L -1 ) Distance from nutrient source (km) Phosphorus (µgP∙L -1 ) Distance from nutrient source (km) Stored P (%DW) Distance from nutrient source (km) Stored P (%DW) Distance from nutrient source (km) Q0Q0 Q0Q Biomass (gDW∙m -2 ) Distance from nutrient source (km) Biomass (gDW∙m -2 ) Distance from nutrient source (km) Before P-removal After P-removal

System Response (to nutrient management) BEFORE P-removal AFTER P-removal

System Response (to nutrient management) BEFORE P-removal growth rate stored phosphorus sensitive insensitive

System Response (to nutrient management) AFTER P-removal growth rate stored phosphorus sensitive insensitive

System Response (to nutrient management) seasonal production standing crop Cladophora (gDWm -2 )

Use In Design (nutrient management and offshore discharge) Shoreline outfall length 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

Cladophora in the Great Lakes Image from – 2005 The “Dark Age of Cladophora”

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

one million gallons of lake water pass through the plant every 3 minutes, sucked in by 3 giant pumps, and filtered on moving, fence-like screens that rotate inside minivan-sized structures. the plant was shut down 3 times in September and October 2007 as Cladophora clogged filters; the shutdown costs the plant between $1.5 million and $2 million a day in lost revenue. James A. FitzPatrick Nuclear Power Plant, Lake Ontario

Growth Mediating Conditions: 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

Go down Moses Go down to Egypt land Tell old Pharaoh Set my people free. African-American Spiritual Moses? Same Lakes – Different Ecosystem

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 Conditions: Light Changes in the underwater light environment impact the depth of colonization.

Pre- and Post-Dreissenid Transparency m depth, off Chicago m depth, off Milwaukee Images from 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 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? In the 1960s In the 1980s In the Dark Age of Cladophora Images from andhttp://

20 Years of Footprints in the Cladophora 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