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GLIN==> New release: Zebra Mussels Effect on Lake Erie's Microbenthic Community

For Immediate Release

August 4, 2000

New Research Suggests Zebra Mussels have Minor Effect on Lake Erie's
Microbenthic Community

For more information contact:
Dr. Robert Heath
Kent State University

or Jill Jentes, Editor
Ohio Sea Grant

Continuing Ohio Sea Grant research by Dr. Robert Heath at Kent State
University and Dr. Joseph Balczon of Westminster College, has found that
unlike other aquatic nuisance species, zebra mussels may have little effect
on microbenthic organisms in Lake Erie.

The microbenthic community, composed of non-harmful bacteria and benthic
fungi, is one of the least studied communities of the Great Lakes. These
organisms, many of which reach 10 to 100 million cells per gram of
sediment, are responsible for many of the lake's key ecosystem functions.
Significant components of the phosphorus, nitrogen, and carbon
biogeochemical cycles, for example, are all performed by these organisms. 

Because zebra mussels eat at the lake's bottom, it is possible that their
feeding activities could disrupt normal processes of the microbenthic
community. Current research suggests that zebra mussels alter the structure
of planktonic communities by efficiently removing small particles from the
water column. 

"When zebra mussels ingest small particles, they either digest and excrete
the particles as fecal pellets or transfer them as pseudofecal pellets
through the mussels' inhalent siphons, " states Heath. What once was
suspended in the water column is now a new energy source available to the
benthic community.

To test whether these increases in particulate organic carbon and nutrients
affect the community, the researchers used controlled laboratory
experiments to replicate microbenthic communities. Their research found
that the particulate releases from zebra mussels stimulated bacterial
production and significantly increased bacterial numbers in the sediment.
These organic alterations to the sediments also extended protozoan
abundance and influenced the protistan species that grew best. Although
zebra mussels' influence on microbenthic communities was greatest in
sediments with very low natural organic content, the study showed that
their effect appears to be minor. 

"Our most reliable observations to date indicate that zebra mussels have a
limited effect on the microbenthic community and are not likely to have
drastic results," states Heath. 

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