Zebra mussels likely contributing to
Great Lakes algae ills
The Star Tribune
Published January 28th, 2005
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 Institute.
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 said.
``Because it smells very similar to sewage, people mistakenly
suspect that the decaying algae is caused by sewer overflows,''
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 last summer.
``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
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.