U.S. Water News Online
CLEVELAND, Wis. -- A rising tide of stringy, smelly algae
on Great Lakes beaches in recent years likely results from zebra
mussels creating clearer water while also adding nutrients to the
lake bottom, researchers say.
The algae, called Cladophora, may get even more blame that it
deserves for the putrid smell, said Vicky Harris, a water quality and
habitat restoration specialist for University of Wisconsin Sea Grant
Zebra mussels often get tangled in the algae and washed up with
it, and the decaying mussels are more pungent than the algae alone --
although that smell is powerful enough to be highly offensive, she
"Because it smells very similar to sewage, people mistakenly
suspect that the decaying algae is caused by sewer overflows,'' she
The mussels are natives of Europe that were inadvertently
transported to the Great Lakes in the bilge water of ocean-going
ships. The algae occurs naturally in Wisconsin waters, growing on
submerged rocks, logs or other hard surfaces and then coming loose
and being washing ashore.
A midsummer die-off of algae, possibly because of warming water,
increases the amount of it that washes up and decays.
New research about the algae, options for cleaning it from beaches
and future plans for monitoring and researching it are to be
presented Feb. 18 at a public forum at Lakeshore Technical College in
Cleveland, just north of Sheboygan.
Shaili Pfeiffer, a water resources specialist with the Department
of Natural Resources, said the forum will give people a chance to
learn about research conducted by various agencies and individuals
"Cladophora is a problem in all the Great Lakes except Lake
Superior,'' Harris said. "We're not quite sure why this type of algae
has made such a comeback from the former nuisance levels in the
1960s, but we know that the water is clearer and light is able to
penetrate more deeply.''
Harris said levels of nutrients such as phosphorus that led to
algae growth in the past have dropped, but the water filtered by
zebra mussels is so clear that sunlight can penetrate far deeper,
allowing algae to grow at depths of 60 feet or more.
Also, the mussels' waste provides bottom fertilizer for algae.
The public forum is being sponsored by the DNR, the UW Sea Grant
Institute, UW Extension, and the Wisconsin Coastal Management program
in the state Department of Administration, a primary funder of
Cladophora-related research and outreach.
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