State on lookout for zebra mussels

Colorado isn’t taking chances this summer with Dreissena polymorpha, a 1- to 2-inch striped bivalve that has invaded the state and has no natural enemies.

Mandatory boat inspections are under way at 58 lakes and reservoirs throughout Colorado, including Rampart Reservoir in El Paso County, to prevent the spread of zebra and quagga mussels.

Zebra mussel larvae, called veligers, were first discovered in Lake Pueblo in fall 2007, and have since been found in seven more Colorado lakes and reservoirs.

If the mussels spread, officials worry they could clog pipes to water treatment plants and damage ecosystems.

The mussels are a non-native invasive species that have been spreading west from the Great Lakes, where they are responsible for millions of dollars of damage to city power and water treatment plants.

Boat inspections — mandatory for boats carried on a trailer — are an attempt to curb the mussels’ spread by cleaning and drying out boats. The larvae can only live in the water, so a dry boat means no critters are transported from lake to lake.
The recent spread of zebra mussels and other invasive creatures is partly due to the popularity of the Internet, said Michael Seraphin, a Colorado Division of Wildlife spokesman.

Bargain shoppers who find online deals on boats from other parts of the country can unknowingly transport nonnative plants and animals around the country.

In Colorado, even small bodies of water like Prospect Lake have signs asking boaters to make sure their craft is dry and clean before entering the lake, Seraphin said.

“We’re in an all-out prevention mode right now to prevent spread,” Seraphin said. “Once they get established, as far as we know there are no known ways to get rid of them.”

Although no one has identified adult mussels yet in any Colorado lakes, experts say they’re just staying hidden.

The adult mussels live between 150 and 300 feet underwater, where biologists generally do not search, said Elizabeth Brown, state invasive species coordinator for DOW.

Adult mussels typically begin washing to the surface of lakes three to five years into an infestation, so scientists look for the larvae as an early sign of infestation.

Water facilities can run up huge repair bills when the mussels build up shell deposits in pipes.

The mussels feed by filtering nutrients out of the water, which kills resident algae, said Doug Krieger, senior aquatic biologist with the Division of Wildlife.

“If you want the place to look like a swimming pool, that’s fine, but it destroys phytoplankton, which is the base of the food chain,” he said. “It affects the whole food chain, from phytoplankton to zooplankton to bugs to fish.”

Colorado Springs Utilities is paying a total of $64,000 this summer to fund boat inspections at Rampart, Turquoise and Twin Lakes reservoirs, spokeswoman Patrice Quintero said in an e-mail.

In the worst-case scenario, mussels would attach to the water pipe out of Rampart Reservoir and the reservoir might be shut down, Quintero said.

“We’re going to make sure every step is taken to ensure no mussels get in there,” she said. “We have contingency plans if something happens, but we feel like we’re in a pretty good place.”

ZEBRA MUSSELS 101

What are they?

The zebra mussel is a type of bivalve that gets its name from the dark striped pattern on each shell. Generally, zebra mussels are small, averaging about an inch long.

Where are they from?

Zebra mussels are native to freshwater rivers and lakes in Eastern Europe and western Asia.

When were they first found in the United States?

Zebra mussels were discovered in Lake St. Clair in 1988. Lake St. Clair is east of Detroit, between Lake Huron and Lake Erie.

How did they get here?

Scientists generally agree that zebra mussels entered the Great Lakes as the result of ballast water being dumped by large ocean-going vessels from Europe.

Why should we care about the zebra mussel?

The zebra mussel has the potential to inhabit most of the fresh waters of the U.S. and could affect a variety of native aquatic species and eventually entire ecosystems. The mussels have had a large economic impact already. Many power plants and water users have had to spend millions of dollars cleaning out zebra mussels from their facilities, as well as retrofitting facilities with devices to keep the mussels out and to monitor for them. These costs get passed along to consumers.

 -- U.S. Geological Survey