Preserving Zebra Mussel Veligers

From September 17, 1990 (update #4)

The type of medium that should be used to preserve water column (plankton net tow) samples was a subject of scientific debate when we were setting up the Wisconsin Zebra Mussel Watch project last spring. An Ontario Ministry of Environment publication (The Zebra Mussel, Dreissena polymorpha: A Photographic Guide to the Identification of Microscopic Veligers) recommends use of a sugar-formalin solution (4% formaldehyde), warning that "veligers are very sensitive to fixatives and preservatives." However, safety considerations related to the use of formaldehyde, a suspected carcinogen, prompted us to search for an alternative. In a series of recent tests of samples collected near The Ohio State University's Stone Laboratory on western Lake Erie, University of Wisconsin- Madison biologist Charles Ramcharan used a number of different preservatives to successfully preserve zebra mussel veligers for short-term identification - that is, for examination within several days after preservation. The preservatives used were a sugar-formalin solution (4% formaldehyde), gluteraldehyde, 70% ethanol and Dufano's solution (a mixture of Lugol's solution, a commonly used zooplankton preservative, plus formaldehyde). Following these tests, Ramcharan is confident that 70% ethanol can be used for short-term preservation to identify the presence of veligers in a plankton sample. However, his experience also suggests that denatured alcohol may contain solvents that interfere with preservation and so should be avoided, or tested with known veligers, before use. NOTE: Anyone using pure ethanol will have to obtain a permit from the U.S. Bureau of Alcohol, Tobacco and Firearms.

ID: 19900917-5.

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.