LAKE COUNTY — Norm Anderson, retired biologist and vector control ecologist knows Clear Lake well. Wednesday, he toured the lake with community radio programmer Carl Shaul, a UC Berkeley graduate who hosts a show on ecology.
Anderson took samples from the bottom of the lake using an Ekman dredge to recover silt containing up to 18 of the different species that line the lake bed.
Among them were tiny, squirming red Chironomidae, or what eventually become midges. Separate from the Clear Lake gnat that DDD nearly wiped out in the 1950s, the harmless bugs swarm around lights during the summer.
Few were found in the silt Wednesday, as most are swarming in the air.
“I estimate that I”ve probably dug 10,000 holes in Clear Lake,” Anderson said, as he towed the line of a box-shaped metal dredge out of the waters.
Although they”re aiming for the lake, midges sometimes drop eggs on cars, which can damage paint, or on buildings near the water. When it rains, they swell, and take on the appearance of small, slimy jellyfish, as was the case several years ago when a Clear Lake High School teacher brought the specimens to Anderson to identify.
“People thought it was raining jellyfish,” Anderson said.
Anderson worked at the county”s Vector Control for nearly 30 years, from 1975 to 2004. He trained current Vector Control biologist Bonnie Ryan, a Long Beach State University graduate.
At the lakeside, Lakeport office, Ryan explained how since 2005, there have been “positive pools” of mosquitoes carrying West Nile virus in Lake County. While people have not been affected by the disease so far in the county, there have been cases affecting chickens and horses. Part of her job is to try to determine the age of the vectors.
By cutting through a mosquitoes” ovaries, she counts “relics” or marks left when an egg is released, which helps narrow down a mosquitoes” age. “The older it is the more likely it is to be vectoring things (carrying disease),” Ryan said.
She and Anderson said this year, because it was a dry spring, the county will see less mosquitoes.
But there will be more aquatic weeds. “You can see four meters down,” Anderson said, using a Secchi disk depth measurement tool, a black-and-white disk that slowly lowers into the lake until it disappears.
“That is very unusual. The lake is very clear,” Anderson said, which forecasts tremendous weed growth for the summer.
Anderson said the Hydrilla that infests Clear Lake came from North Carolina and the Deep South, and thinks it likely was brought by a bass boat.
Anderson explained how he introduced many UC Davis, Stanford, UC Berkeley and other researchers to Clear Lake, helping with their research on the effects of DDD on the lake, as well as mercury and studies to determine the age of the lake.
He said the age is in the hundreds of thousands and possibly one million years old. It is a shallow lake, at depths of 60 feet. There is one “chimney” in the lake near Buckingham Point off of Shag Rock about 80 feet deep. Bubbles are visible in that area of the lake, coming from the chimney.
Several years ago, Anderson gave a tour of the lake to a journalist from the East Coast, who had read the reference to Clear Lake”s grebe die-off after DDD in Rachel Carson”s Silent Spring. “She was looking for doom and gloom, and she didn”t find it.”
“I think when people think of Clear Lake, they think of derogatory things. But it”s been my experience that it”s a pretty healthy lake. It has five times the organisms of Lake Tahoe,” Anderson said.
He said part of the reason why the lake is so old and hasn”t turned into a meadow is because it lies in an area between two faults that is sinking at a rate comparable to sediment build-up, meaning that the depth stays consistent. In addition, there is a lot of sediment movement both into the lake and out of it ? water molecules have a life of seven years from when they enter the lake until they leave via Cache Creek.
Contact Elizabeth Wilson at ewilson@record-bee.com
