COLUMBUS, OH - Continuing Ohio Sea Grant research by Robert Heath at Kent State University and 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.
Add'l contact: Jill Jentes, Editor, Ohio Sea Grant, (O) 614-292-8949, Email: jentes.1@osu.edu