Aliens in the West - Quagga Mussels Invade Western Waters
By W.O.N. staff
Disease. War. Natural Disasters. A half-inch bivalve.
What do all these have in common? They are all the focal points of some of the largest mobilizations of money and manpower in the history of state and federal government. And while one of these may not pose a direct threat to human life, its potential economic impact in the West and the latent effect on recreational fishing and boating are ominous.
The culprit we are speaking of is Dreissena bungensis. A familiar name to fisheries biologists, but to the layman it is commonly called the Quagga mussel. A close relative of the Zebra mussel, the Quagga mussel is a non-native species with roots traced back to the Dneiper River drainage in the Ukraine. Ranging in size from microscopic to about 2 inches long, Quagga were inadvertently introduced into the Great Lakes system in the early 1980’s from the hold of a ship. Since that time, the Quagga colonies spread rapidly, overwhelming the Great Lakes and the Mississippi River drainage, St Lawrence Seaway, and are currently working their way up the Missouri and Arkansas rivers. The resulting direct economic impact for mitigation is estimated at one hundred million dollars per year. This does not include the secondary or environmental impacts the Quagga has brought to bear.
Mature Quagga Mussels
The crisis in the West came to bear on January 6th of 2007 when a diver working on some docks at Lake Mead marina found an unfamiliar mollusk attached to a steel cable. Over the next few days, subsequent dives located more of these mussels, which were later identified as Quagga in the Lake Mead Hatchery, Las Vegas boat harbor and Callville Bay. Dives at other sites along the Colorado River drainage had located Quagga in waters of Lake Mohave, Lake Havasu and the Colorado River Aqueduct system. As of early September 2007, Quagga had spread to Southern California waters including Lake San Vicente, Lower Otay lake, Lake Dixon, Lake Wohlford, Lake Matthews and Lake Skinner. As Dixon and Wohlford do not allow public boat access, it is speculated that the bivalves were introduced as “veligers” – the microscopic larval form of the Quagga - via water transfer from other infected impoundments or possibly by waterfowl. Additionally, a close cousin of the Quagga, the Zebra mussel has been discovered in San Juisto Lake in Central California; it’s introduction a likely result of transportation via boat.
Although small in size, Quagga mussels are voracious filter feeder whose prolific reproduction has grabbed the attention of every governmental agency that has anything to do with water in the West. A Quagga adult can produce over 1 million eggs a year and their petite size make them hard to detect in small numbers. Quagga live from 2 to 5 years and can be found at all depths as long as a sufficient amount of oxygen is present. Quagga mussels prefer to attach to hard surfaces such as pilings, docks, boat hulls and concrete. Mussel populations on stationary structures of these types can run as high as 750,000 Quagga adults per square meter. Colonies of this magnitude effect water intakes, pumping stations, cooling inlets, ballast intakes, locks and other manmade structures. Their obstruction of valves, screens, impellers and other moving mechanisms wreak havoc with irrigation, pumping and hydroelectric systems.
The ecological impacts of the Quagga mussel are even more horrifying to fisheries biologists and fishermen alike. Quagga mussels are filter feeders with an individual specimen capable of cycling a liter of water per day. They remove phytoplankton and other microscopic nutrients, which act as the building blocks of the aquatic food chain. When you consider a single Quagga can filter nearly 100 gallons per year, it is easy to see how colonies of millions can negatively influence a body of water.
In the Great Lakes, studies have shown that Zebra and Quagga mussels are responsible for a 90 percent reduction of phytoplankton in Lake St. Clair, a 60 to 90 percent reduction in Lake Erie, and an 85 percent reduction in the Hudson River once large colonies were established. While the Quagga did get credit for improved water clarity, the resulting blooms of bottom-dwelling algae offset this gain by creating taste and odor problems with the water supply. Additionally, nearly all fish species found in areas infiltrated by the Quagga have suffered due to the strain on the food chain. These invaders threaten even indigenous clam species. Quagga will attach to the outside of their shells and eventually smother them by preventing them from feeding.
In addition to their filtering activities, these small mussels retain up to 300,000 times the safe level of toxic contaminants in their flesh. Diving waterfowl that dine on the Quagga have subsequently experienced higher than normal levels of toxins in their tissues. They have also seen an increase in the mortality rates of their hatchlings as compared to those fowl that do not eat bivalves. The Quagga have no known natural predator and other than the occasional duck, catfish, or sunfish that may dine on Quagga, nothing in the marine environment can keep up with their rapid proliferation.
Quaggas attached to cinder block at Lake Havasu
The crisis gets multiplied here in the West with states like California. Not only is California home to some of the highest concentrations of freshwater, amphibian, and aquatic invertebrates who are on the rare or endangered species list, but the state also has a system of waterways which are highly dependant on transporting water over long distances via pumping stations, aqueducts and reservoirs. Much of the southwest including Phoenix, Las Vegas and Southern California rely on water from the Colorado River, which is already under siege from the Quagga. Add to this the fact that the composition and conditions of most western impoundments are more physiologically suitable to habitation by Quagga mussels than eastern waters, and you have the makings of a potential disaster.
Since the discovery of the Quagga in Lake Mead, a multi-agency response has been initiated aimed at curtailing the advance of this mollusk. All 16 California Agricultural stops along the highways leading into the state have been re-opened for boat inspections. Numerous lakes throughout the state require Quagga mussel paperwork be filled out by boaters prior to entry. Some lakes are even requiring on site inspections; others are contemplating boat wash-downs prior to launch. Tournament organizations are being asked to provide information on their participants to various water districts. The list of current and pending requirements grows daily as each entity decides how best to deal with the situation.
In addition to the multi-agency mobilization aimed at limiting the spread of the Quagga, a massive public information campaign has been launched, aimed at all segments of the population who use public waterways. Information flyers and brochures are distributed at border stops, lake entrances, and tackle shops. Future boating registrations, mailings and fishing license applications will likely include information on the Quagga. Public information spots are being filmed for broadcast by larger water districts. Even the local press is picking up on this story.
For those who may doubt the possible impact to anglers and recreational boaters as a result of the Quagga Mussel infestation, a paper issued in May of 2007 by the California Science Advisory Panel to the numerous agencies involved in addressing the Quagga crisis cuts right to the chase in its recommendations: “To prevent further transportation of D. bungensis out the these waters, the following actions should be taken, 1) Lakes Mead, Mohave, and Havasu should be closed to boating until eradication efforts are complete. 2) If the lakes are not fully closed, before leaving the National Recreation Area, all boats should be cleaned by the National Parks Service staff or their certified agents...” Other dire suggestions included the possible draining of already low Lake Mead by another 76 feet, denying boating access to uninfected waters, and eliminating fish stocking from hatcheries using questionable water sources to raise their fingerlings.
While the National Park Service weighs the political impact of closing public waters, municipal water agencies have no such concerns as they merely answer to their Board of Directors. As such, recreational uses of their impoundments play second fiddle to their primary job of selling water. Potential closures of major bodies of water are a possibility that is to be taken seriously. Many smaller water districts do not know how to adequately address the incursion and have limited financial resources to deal with the problem. Faced with these obstacles, closures are the most effective and economical approach to stopping the spread of the Quagga. Casitas Lake has already taken this draconian step and others are sure to follow.
In the face of this predicament, boaters are being asked to take a proactive role in stemming the further incursion of this invader. Once a boat is pulled from the water, the hull should be thoroughly washed with soapy water and a concentration of at least 5% bleach. Foreign matter such as aquatic weeds or mud should be removed from the trailer or your tow vehicle. Bilge plugs should be removed and livewells completely drained and dried. The outboard or lower unit should be flushed and completely drained of water. Buckets or coolers that contacted or may contain lake water should be completely drained and washed. Any remaining live bait should be thrown away.
It is also recommended that any boat coming out of one body of water to another remain dry and out of the water for a minimum of 5 days before being introduced to another lake or river.
Now that they have made their incursion into the west, the task of mitigating the Quagga will be an undertaking that will be ongoing for many years into the future. The clean and dry transportation and storage of boats is the wave of the future for all vessels in the Western United States. By doing your part to help contain the spread, you just might be insuring that your ability to boat on the waterways of California remain intact for years to come.
For further information on Quagga mussels, a multitude of websites whose links are shown below are available for your review. These contain information on the Quagga and Zebra mussels and methods to mitigate their spread.
Photos courtesy of the Metropolitan Water District (MWD)