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Multiple Stressors, Multiple Consequences
Muck, harmful algal blooms and changing fisheries plague Saginaw Bay; researchers look into why
Photo Credit: Juli Dyble Bressie |
"The smell sensation you get is like you are standing in a barnyard," longtime resident Warner Price, 74, said describing the "dark, black, decaying mess" that has been caking his beachfront property for the last decade.
Price a resident of Port Austin – at the top of Michigan’s thumb – for 63 years, said throughout this time the quality of fisheries and water went in waves. As the lake area first began to deteriorate in the 1970s, he saw government regulations which helped solve problems. Now, the problems with algae, muck, fisheries and poor public perception of water quality have returned.
The Great Lakes Environmental Research Laboratory is in the middle of a research project – Managing Multiple Stressors in Saginaw Bay – which seeks to understand the effects of factors such as invasive species, water levels and phosphorus on water quality and fisheries in the bay. The project uses an Adaptive Integrative Framework (AIF) approach, which facilitates continuous feedback between researchers and managers to identify effective management solutions. For Saginaw Bay, stakeholders identified water quality concerns including muck, pathogens, and nutrient loading and fisheries concerns including yellow perch and walleye recruitment, and feasibility of reestablishing lake herring in Saginaw Bay.
 Photo Credit: Juli Dyble Bressie |
The study is now in its second year (a major field research year) and project lead Craig Stow (GLERL scientist) said they are in the process of identifying a lot of unknowns.
"You have to sort out cause and effect relationships in the ecosystem when you have so many variables at once," Stow said.
For example, invasive zebra and quagga mussels, which entered the Great Lakes in late 1980s, may increase phosphorus availability near lake bottoms. As filter-feeders, they also clear the water allowing more light to reach the bottom of the lake. These two actions increase the likelihood that bottom-dwelling algae will grow to nuisance levels. These mussels have also been shown to spit out toxin-producing algae during filtration, returning them to the water, possibility promoting more extensive harmful algal blooms. The mussels may also impact native fish populations (walleye and perch specifically) by competing with invertebrate prey and altering water clarity.
 Photo Credit: Juli Dyble Bressie |
"Everything is so interrelated," said Juli Dyble Bressie, a GLERL researcher focusing on water quality issues. "That’s the cool part, but it’s also the hard part."
Tomas Hook, a Purdue researcher co-leading fisheries research with Steven Pothoven (GLERL scientist), said he hopes this project will lead to a better understanding of the system, and thereby improve management of important Saginaw Bay resources.
Stow said he hopes other coastal areas experiencing problems with multiple stressors can use some of the methods employed at Saginaw Bay.
"Saginaw Bay is sort of a microcosm of problems that are occurring in a lot of coastal areas," Stow said. "Learning what we can here will affect decisions made specifically for the bay area, but it should also have more general application in other coastal ecosystems."
7/6/2009
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