• Increase font size
  • Default font size
  • Decrease font size
  • default color
  • green color
  • red color

California Special Districts Association

Wednesday
Sep 08th
Scientists Share Wonders of Life in Clear Lake
Written by Elizabeth Larson   
Chironomids, Chaoburus astictopus, bryozoans, daphnia, zooplankton and phytoplankton.

Some of those terms may be familiar or they may be something many Lake County residents haven't heard before, but they are part of the vibrant life and language of Clear Lake.

Understanding what those creatures do and how they impact life in the lake gives both a greater appreciation of the unique ecosystem and a better idea of what's needed to protect it.

A Thursday night educational presentation looking at those strange and wonderful – and sometimes infuriating – creatures that live in Clear Lake and make up its intricate food web drew dozens of people.

The Lake County Fish and Wildlife Advisory Committee held the presentation during its regular meeting at the Board of Supervisors chambers in the Lake County Courthouse in Lakeport.

The committee's chair, Greg Giusti, said the goal was that people would walk out of the presentation with a better understanding of Clear Lake than they had when they arrived.

So many people wanted to attend that extra chairs had to be brought in, with people spilling out into the courthouse foyer. More than 100 people crowded into the chambers for the nearly two and a half hour meeting.

Looking out over the crowd, Giusti said, "Admittedly, we don't have quite this many people at our other meetings."

One of the county's best kept secrets is the Lake County Vector Control District, Giusti said, and its staff gave a presentation about the work they do and shared information about the lake.

"Wow! It's a few more people than I was expecting," said Dr. Jamie Scott, vector control's district manager and research director.

"There's a lot of neat stuff" that's in the lake, she said.

Scott gave a brief description of the district's duties, explaining that vector control is a special district and not a part of the county government. It serves the entire county and answers to a separate board.

She said vector control's mission is to provide citizens with the highest practical level of protection from vectors and vector-borne diseases.

Funded through property tax, "We are a public health agency and we provide a public service," she said.

For the district's first 30 years the Clear Lake gnat was "really the most important thing that we did," Scott said, showing pictures of resort signs coated with the critter, which also covered windshields and headlights.

Vector control was established in 1948 specifically to deal with the gnat – known as Chaoburus astictopus – a nonbiting midge that reached "extraordinary nuisance densities" in the 1950s and 1960s, Scott explained.

Today, the district focuses more on mosquito control and preventing the transmission of West Nile Virus, but Scott said they also conduct disease surveillance, work with the public health department on West Nile Virus outreach, work to prevent tick-borne disease and do arthropod identifications.

Scott said the two most common mosquitoes in Lake County are the treehole, Aedes sierrensis, and the snow melt mosquito, Aedes increpitus. The wet, windy spring limited how much spray vector control could put out this year.

Exploring life in the lake

Vector control biologist Bonnie Ryan gave the bulk of the presentation, which she called "Life in Clear Lake (It's the little things that count)."

The young biologist, who grew up in Lake County and received her degree from Long Beach State, said this is her 10th season working with mosquitoes, and she really enjoys the lake work that the district does.

Ryan explained the three sections of the lake: the littoral zone, including the shoreline and shallow wading areas; the limnetic zone, or open water area; and the benthic zone, which covers the bottom of the lake.

She showed a diagram of a "simplified" food web which resulted in laughter because the diagram had dozens of arrows and lines and balloons, and looked far from simple.

"It's extremely complex and on top of that it's what we consider a dynamic system," she said.

The system changes if nutrient loading or population densities are altered, and according to seasonal changes, she said.

Ryan's simplified version of the food web was: big things eat littler things.

Fish like the large-mouth bass are at the top of the food chain, Ryan said. The fish eat invertebrates like Clear Lake gnat larvae, which in turn eat zooplankton, which eats phytoplankton.

Vector control staff showed different kinds of equipment they use for lake monitoring, including a fine mesh net called a vertical tow that allows them to collect plankton from each of the lake's arms nearly every month. A Secchi disk measures for water clarity.

Ryan explained a number of the organisms in the lake, from phytoplankton – "the true algae" – to blue green algae, which more appropriately is cyanobacteria.

Among the blue greens, the genus lyngbya was the most troublesome last year. Blue greens are able to outlast their true algae relatives because they have gas vesicles that regulate buoyancy and allow them to get to the surface quicker, she said.

Green algae, or chlorophyta, has 7,000 species and is in nearly every fresh water body. "This is an extremely important food group for zooplankton," she said.

Other food sources for zooplankton include the yellowish-green bacillariophyceae, which have cell walls composed of silica, and dinophyceae, which are motile and use a big long hair to swim around.

She showed several live slides, including one of algae that looked like little fuzzy balls.

Another slide showed zooplankton, including tiny critters moving around the slide. "If you fall over wakeboarding, you get at least a couple dozen of these up your nose," Ryan said.

Showing a tiny daphnia, or water flea, Ryan explained its rudimentary circulatory system. The creature is a planktonic crustacean in the order cladocera.

Zooplankton, she said, are very small animals that don't photosynthesize and which eat phytoplankton.

She also went over a number of other little creatures, from the rotifera, crustacea, ostracoda and porifera – which are sponges. Then there are bryozoans, a moss creature similar to coral and what Ryan said was one of the oddest looking things in the lake, resembling brains.

Also in the lake, Ryan said, are native mollusks – clams, mussels and snails – oligochaetes, or aquatic earthworms, hirudinea or leeches – none of those found in Clear Lake parasitize people – diptera, or flies, and charoboridae, or the phantom midge like the Clear Lake gnat.

The nonbiting gnat, she explained, is very small, and has specialized antennae to capture prey. It lives in the muck during the day and hunts in the water column. Ryan said fish are attuned to its lifecycle and use it as a food source.

The Clear Lake gnat only lives for a few days when in its adult life stage, with most of its life spent as larvae in the mud, she said.

Ryan said vector control does counts of Clear Lake gnat larvae. Over the last 10 years the greatest number of immatures gnats found per dredge is less than two and a half, compared to a high of 115 in 1959. The highest numbers are found during the winter.

Chironomidae, nonbiting midges – or rice flies – are more abundant, about 80 per dredge, she said. She said the midges are part of a huge family, with 2,000 species in just North America. They're found in almost every freshwater body.

"It's a very, very prolific family," he said, noting that the midges spend most of their lifecycle in the mud.

Explaining the difference between midges and mosquitoes, Ryan said a midge doesn't bite and only lasts a few days, while mosquitoes can last up to a few months and do bite.

Chironomids usually are found in huge groups, different from mosquitoes. Ryan said mosquitoes have a large proboscis used for biting, and chironomids like to hold their legs over their head, while mosquitoes put their legs down when landing.

Showing more live slides, Ryan showed an aquatic earthworm, a Clear Lake gnat and a bright red chironomid, red because it contains hemoglobin which is used to transport oxygen.

Ryan next discussed fish, explaining that they are visual feeders – meaning they need to see to eat.

She said there are four native fish species in Clear Lake – the tule perch, hitch, Clear Lake splittail and the prickly sculpin.

Silverside and threadfin shad, which are schooling fish, eat zooplankton and compete with the Clear Lake gnat for that food source, which Ryan suggested may have helped keep the gnat's numbers down.

But numbers for both kinds of shad last year appeared lower than they have been, Ryan said.

Anderson offers longterm perspective on lake issues

Retired vector control biologist Norm Anderson followed Ryan in the presentation.

He came to Lake County in the mid 1970s, when phytoplankton dominated the lake. At the time, there were nuisance blue green algae blooms.

Attempts in the early 1980s to get rid of some of the algae included a skimming effort conceived by Ed Headrick – known as the "Father of Frisbee" and disc golf. Anderson said a vector control barge was used in the effort, but it didn't prove successful.

They also tried skimming and spraying, with the latter yielding only short-term results. Using a boundary technique composed of fire hoses provided to be too much of navigational hazard, he said.

One thing that did help – installing a sewer system around the lake to replace septic systems meant less problems with nutrient-rich problems, Anderson said.

In the spring of 1990 a "clear water episode" resulted, with the lake so clear that even Soda Bay was clear to the bottom. Anderson said aquatic macrophytes – or plants – got a foothold and have been growing ever since. That includes creeping water primrose.

Since then, there has been a proliferation of organisms in the littoral zones, said Anderson. In the early 1990s the invasive water plant hydrilla was discovered. The California Department of Food and Agriculture took the lead on trying to eradicate hydrilla.

Anderson said vector control scientists occasionally check other local water bodies – Lake Mendocino, Lake Pillsbury, Blue Lakes, Hidden Valley Lake – to see if there are correlations to what is happening in Clear Lake.

He showed a slide of a daphnia from Lake Mendocino that had developed a little pointed structure on its head in response to being preyed upon by other organisms in that lake.

Biologists occasionally will spot something they've not seen in the lake before. Anderson recounted his excitement over finding a leptadora, or a giant water flea, in the mid 1980s.

"Every once in a while you find something new. It's exciting," he said. "Clear Lake is a dynamic ecosystem. It's changing all the time."

He asked if anyone remembered the episode of raining jellyfish.

Anderson recounted an incident several years ago when, in late fall, chironomids were doing one of their last seasonal emergences. There was wind and a rainstorm, and the wind blew them to Lakeport, where they ended up on cars, structures and awnings at the school.

When the rain hit, "We had all this jelly goo dripping everywhere," he said, and the news from San Francisco reported it was raining jellyfish at Clear Lake.

He said Don Gatton, a teacher at the school, brought some of the goo up to the lab, and they were able to identify it as chironomids. "You know what, people preferred the raining jellyfish," Anderson said.

Scientists field questions

During a 45-minute question and answer period, people asked numerous water-quality related questions, most of them related to algae.

Dr. Harry Lyons of Yuba College, responding to a question about keeping lyngbya moving to prevent problems like there were last year, said he thought it was good advice.

He drove around the lake on Thursday and said he didn't see what he saw last year.

Moving the lyngbya helps keep it alive, he said. "It's like me – as long as it's alive it doesn't smell too bad."

The cold winter didn't kill the lyngbya as Lyons hoped it would. "The lake has changed its regime and we'll have some lyngbya," which he suggested will require tactics including traditional methods like spraying and harvesting.

Long-term projects that can help the algae issues include the Middle Creek restoration project, conservation easements along the shoreline and saving shoreline tules, he said.

While lyngbya can be a headache, Lyons pointed out that it also is part of the lake's massive process of removing carbon from the atmosphere.

He did a calculation over a beer that afternoon, considering how much carbon the 65-square-mile lake removes, and he estimated that every two hours 168 million grams of carbon is removed from atmosphere and made into carbohydrates or things like lyngbya.

He said if people ask about global warming, "Up in Clear Lake we're doing our share."

Lyons asked people to be patient and understand that the system is complicated.

"Clear Lake isn't for sissies, and that's OK because I don't see any sissies in this room," he said.

Asked about the floating islands project in Clearlake Oaks, Lyons said global problems can be addressed by local actions, and the floating islands will help. It's not a global solution but a "forceful, spirited response."

In a non-algae question, one woman asked about how quickly ticks bit their hosts.

Dr. Bob Lane, a Nobel laureate, tick expert and the man who identified Lyme disease on the West Coast, was on hand to answer the question, explaining that different kinds of ticks behave differently.

He said the American dog tick and the Pacific Coast tick are common ticks in Lake County. The Pacific Coast tick carries Rocky Mountain spotted fever, but isn't an aggressive biter.

However, the Western black-legged tick, which passes Lyme disease, will bite right away, Lane said.

"Ticks differ in their aggressiveness, in their willingness to bite humans," he said.

Giusti said he always itches after he hears Lane discuss ticks.

The presentation was broadcast live on TV8, where it will be rebroadcast. It also is available from Velocity Video Online, www.velocityvideoonline.com; call McKenzie Paine to get a DVD at 707-972-5065.
< Prev   Next >
 
HEADLINES
  • Pause
  • Previous
  • Next
1/3
 
 
Banner
Banner
Banner
Banner
Banner

CSDA Magazine

Feature Article:
Recruitment: Friend or Foe?

 

Interview

Interview:
Managing Human Capital in Local Government, Interview with Dr. Frank Benest

 

Solutions

Solutions:
New Challenges in Hiring Leadership for Special Districts

 

Innovations

Innovations:
To FISH* and Beyond . . .

 

 

What's So Special

What's So Special:
Public Service In and Out of the Office, Coachella Valley Water District (CVWD)