LAKE COUNTY – “No news is good news,” said county Deputy Director of Public Works Pam Francis. She heads up the department”s Water Resources division, and was referring to the fact that lab experts are telling her that so far no evidence has been found in samples from Clear Lake taken to determine whether the county”s prized lake is infested with the costly and invasive zebra mussel, or its cousin the quagga mussel.
But the verdict isn”t in yet on Clear Lake. Those tasked with sifting through the sludge collected using a special 60-micron net several weeks ago are still doing just that – sorting through the mire. A micron is one millionth of a meter, meaning a 60-micron net has a very small mesh that, when dragged through the water, collects a lot more than plankton.
“(The net) collects everything in the water,” said Francis, which includes silt, plankton and aquatic plants. “They”re looking for a needle in a haystack.”
That may explain why conclusive results aren”t back after the county”s Water Resources Division sent off seven sets of samples to the Bureau of Reclamation laboratory in Colorado several weeks ago.
The California Department of Fish and Game (DFG) collected and sent a set of surface samples just a few weeks ago as well to Portland State University”s Center for Lakes and Reservoirs.
The tests were ordered after a presentation to the county Board of Supervisors near the end of May that detailed just why the little creatures are such a threat. The board took immediate action, dedicating $10,000 from Transient Occupancy Tax dollars to educate the public and test for the mussel.
The zebra and quagga are mussels of the genus dreissena, which originated in eastern Europe, according to DFG spokesperson Alexia Retallack. They invaded the U.S. In 1988, arriving in the ballast water of seafaring ships at dock on the Great Lakes when the water was release to take on cargo.
The tiny mussels start out microscopic as a veligers, as they are known in their larval stage, and are detectable only as a sandpapery texture on a normally smooth surface.
The problem is that they reproduce at almost unfathomable rates. One mussel lays up to one million eggs at a time. At a three percent survival rate, that one mussel could spawn 30,000, and when those lay eggs, it”s easy to see how such a tiny creature could cause big problems.
The price tag just to maintain the quagga and zebra mussel populations in the Great Lakes region is $36 billion.
The mussels filter out photo plankton in fresh water, making the water very clear, explained Retallack. Smaller invertebrates, fish and zooplankton feed on the photoplankton and cannot thrive without it, leaving bigger fish nothing to eat, and so-on.
Quaggas are actually the worse of the two species, according to Retallack, because they attach to both soft and hard surfaces and at deeper, cooler depths, where they are harder to find. Both need calcium to form their shells, meaning that high-nutrient watercourses are considered “at risk” of infestation. Clear Lake is on a list of 160 such high risk areas in California because of its calcium content. Those water bodies have yet to be prioritized, pending solid scientific evidence.
Contact Tiffany Revelle at trevelle@record-bee.com.
