Saginaw Bay's algae problems could get worse before improving
Written by Bay City Times   
Friday, 10 April 2009 14:11

Scientists believe they're dealing with a new beast in Saginaw Bay, or at least one they didn't think was there.
A species of algae called spirogyra may be more prevalent in the bay than has been thought, said Craig Stow, a researcher with the Great Lakes Environmental Research Lab in Ann Arbor, part of the National Oceanic and Atmospheric Administration.

''This summer, we hope to get a better handle on what's really happening out there,'' Stow told about 25 people during a presentation Tuesday at the Bay City State Recreation Area's Visitor Center in Bangor Township.

For years, researchers have thought cladophora, another species of algae widespread throughout the Great Lakes, was also the predominant form of the plant in the bay. But Stow said the first year of a five-year federal research project suggests that spirogyra may be more prevalent.
''The dominance may have shifted,'' he said.

And that's a potentially bad sign, since spirogyra responds to lower levels of phosphorus, a nutrient that's been helping fuel problems with dead algae, or muck, in the bay in recent years.

What's also different about spirogyra is that it floats, rather than attaching itself to rocks or the backs of zebra and quagga mussels on the bottom of the bay, Stow said. That means the source of muck problems may be harder to pinpoint.

Mike Evanoff, unit supervisor at the Bay City state park, said he's hoping for a better year than normal for muck at the park beach. Forecasters have called for higher water levels in Lake Huron this year, and the shallow Saginaw Bay could benefit from that, he said.

This year's springtime cleanup of muck on the park beach, using beach grooming machines, is due to begin in a few weeks, Evanoff said.
Stow said excess algae and muck in the Great Lakes, and Saginaw Bay, has been a problem dating back to the 1920s. An international Great Lakes Water Quality Agreement signed in 1978 set goals for reducing phosphorus loading from detergents and point sources like wastewater treatment plants.

Those measures seemed to work, and by the late 1980s, victory had been declared against algal blooms, which turn into muck when they die off and wash up on beaches.
But muck began to return to Saginaw Bay in particular in the early 1990s, possibly due to a dip in water levels, along with warmer waters due to climate change and an influx of aquatic invasive species like the zebra and quagga mussel.

There's also a chance that Saginaw Bay has tipped beyond the point of a typical recovery, Stow said.

Bay County officials have instituted restrictions on most residential lawn fertilizers this year in hopes of helping the bay recover from years of phosphorus loading.
Stow said scientists used to think algae increased proportionately with the level of phosphorus. But water bodies can change quickly from bad to good when it comes to excess algae.

So returning the bay to a level of phosphorus below that which triggered algal blooms may not be enough; an even lower level of phosphorus may need to be achieved, he said.

That's partially due to phosphorus trapped in sediments from earlier loading that can be stirred up and reintroduced to the ecosystem, Stow said.
''We could be in a state that no levels of reduction may have an effect,'' he said.

He and other researchers hope to discover more during research this summer and in 2010.

''So far, we've identified more questions than answers,'' he said.

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