Mussels Infest Milwaukee

From September 10, 1991 (update #10)

MILWAUKEE -- By mid-August, zebra mussels were being found in every water sample from and on all substrate samplers in the Milwaukee area examined as part of the Wisconsin Sea Grant Zebra Mussel Watch. Representative observations included:

* Veligers were found Aug. 2 in plankton tows taken near the southern gap in the outer harbor.

* Recently settled post-veligers were first found Aug. 5 on samplers placed at Admiral's Wharf marina at densities of 312 per square foot (29/m2). Plankton samples taken at the same time contained veligers at densities of 79 per gallon (300/L). Two weeks later, water sample densities were about the same, but post-veliger substrate densities had jumped to more than 19,376 per square foot (1,800/m2). Similarly, in just 18 days substrate densities increased from 1,044 to 53,821 per square foot (97-5,000/m2) at the Milwaukee Harbor Liquid Cargo Pier between Aug. 12 and 29.

* One post-veliger was found Aug. 5 on a substrate sampler at Milwaukee's McKinley marina, and marina water samples taken at the same time also contained veligers.

* Veligers were found in water samples taken in August at the Northshore Water Utility, Milwaukee Water Works Linwood Intake, Cudahy Water Utility, Oak Creek Water Utility, South Milwaukee Water Utility, Wisconsin Electric Power Company (WEPCO) Valley power plant, Liquid Cargo Pier and UW- Milwaukee Center for Great Lakes Studies dock. Substrate samples taken at the CGLS dock and Liquid Cargo Pier also contained settled post-veligers.

* Diver Paul Wagner reported finding 11 zebra mussels Aug. 13 on the wreck of the SEBASTOPOL, located at a depth of 10 feet (3 m) in the southern part of Milwaukee harbor. The next day, Wagner found 20 mussels at the same depth near the south harbor breakwater.

ID: 19910910-2.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.