BY SHERI McWHIRTER
SUTTONS BAY -- Far more plants have taken root in Grand Traverse Bay compared with a decade ago, a possible sign of ecosystem changes.
Local scientists spent hours crisscrossing both West and East bays last summer, where they counted and measured aquatic plant beds along the bottom. Researchers now point to the study's results as a sign the bay's makeup needs constant surveillance.
The study is intended to provide baseline data to help determine any link between aquatic plant growth, phosphorous cycling, invasive species and avian botulism outbreaks. Aquatic plant growth could be an indicator of shifts in the bay ecosystem.
"We found that the number of macrophyte beds in the bay more than tripled," said Sarah U'Ren, program director at the Watershed Center Grand Traverse Bay.
Macrophytes include rooted aquatic plants such as cladophora, water milfoil and chara.
Researchers found more than 400 such plant beds in the bay, up from approximately 120 found in 1998. Additionally, plant beds are much larger.
"Some are about 10-by-10 feet while others stretch for a quarter mile," U'Ren said.
One theory is invasive zebra mussels filter the water, a process that increases clarity and allows more sunlight to penetrate the surface. That increased sunlight in turn allows more plants to grow.
Nutrient runoff from shoreline residential areas or tributaries that feed Lake Michigan also could explain increased aquatic plant growth, U'Ren said.
Researchers used both aerial photography and the Bay Monitor tugboat to complete the survey.
"We did find more in West Bay than in East Bay and more along the western side of West Bay. I think a factor is that side of the bay has more embayments, like Suttons Bay, Omena Bay and Northport Bay, and we found a lot of macrophyte beds in those areas," U'Ren said.
No cladophora was found, though water milfoil and chara dominated the plant beds, she said.
Researchers also studied sediment samples and learned areas with aquatic plant beds had higher phosphorous levels in the sediment, though water samples didn't show much difference, U'Ren said.
U'Ren will present the study's results at a seminar at 7 p.m. Tuesday at the Inland Seas Education Center, 100 Dame St. in Suttons Bay.
"The aquatic plants have been such a big issue not only in the Great Lakes but also in the inland lakes," said Christine Crissman, education director for the Inland Seas Education Association. "It's important for people to realize what is happening in the Great Lakes."
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