Zebra mussels seen as major threat to native species, boaters, even water systems

Rochester's Chief Water Operator Ian Rohrbacher pictured in front of Rochester Reservoir, which has seen no indication of any zebra mussel activity thus far; inset, the tiny zebra mussel. (Rochester Voice file photo) .

A tiny mollusk native to Asia is threatening the region's native aquatic plants and animals, and even its water supplies, officials in New Hampshire and Maine said this week.

And it's likely still unknowingly being sold in pet stores across the region.

Zebra mussels, a highly invasive and prolific fresh water species, have been found hitchhiking on moss balls, a popular ornamental addition to betta and other small fish tanks.

A look at Rochester Reservoir pictured on Wednesday. (Ian Rohrbacher photo)

Amy Smagula, a fresh water biologist for New Hampshire Department of Environmental Protection and coordinator of its invasive species program, said while zebra mussels have not yet been detected in any New Hampshire bodies of water, she is concerned for the potential danger they present to water supplies and to native flora and fauna.

She said at least two chain department stores, PetCo and PetSmart, have already started removing the moss balls from stores, and NH DES has begun messaging the dangers they present.

Zebra mussels can have profound impacts on recreational boating, by getting stuck in propellers and sucked into intake valves. They can also endanger fish and aquatic plants by releasing extra nitrates into the water that can result in bacteria blooms.

Smagula said next week they would be canvassing New Hampshire's 80 or so pet stores to make sure they not only take moss balls off the shelves but take great pains to destroy the balls that are home to the zebra mussels.

Ian Rohrbacher, Rochester's chief water operator, told The Rochester Voice on Wednesday they are well aware of the damage these critters can do.

"They can foul up intake structure and screens, they get in a lot of nasty places," he said. "They can also get stuck in an impeller, block the screen and run a pump dry. And they contribute to bad nutrients."

To stay ahead of the mussel menace, Rohrbacher said they have a "robust watershed management plan" that monitors bacteria levels and other indicators that would predict their presence.

"We make physical inspections, we go out on watercraft and take samples of nutrients, and if we see any buildup, we address it," Rohrbacher said.

He said they also send divers down annually to check and clean out all intakes.

"The only thing we've seen this year is what would be typical of flora and it's all natural," he said.

DEP officials say that released into the wild, these zebra mussels can quickly outcompete native species, and can clog boat motors, hydropower structures, intake pipes and other in-water structures.

They are sold as aquarium plants that have names including "Beta Buddy Marimo Balls," "Mini Marimo Moss Balls," and "Marimo Moss Ball Plant." These moss balls are sold separately but also often included in the sale of betta fish.

Environmental officials warn that if anyone bought these moss balls, it is important that they are destroyed and properly disposed of immediately, along with disinfecting water if in an aquarium. They warn against flushing the balls down the toilet or disposing of them anywhere they could get into a water system.

How to properly dispose of the moss balls

If you purchased moss balls, destroy them by using one of these methods:

• Freeze - Place the moss ball into a sealable plastic bag and freeze for at least 24 hours.

• Boil - Place the moss ball in boiling water for at least 1 full minute.

• Bleach - Submerge the moss ball in chlorine bleach for 20 minutes

If these moss balls were in a fish tank, the entire tank will need to be disinfected:

1. Remove fish

2. Dispose of all aquatic plants in the same manner as the moss ball, either by freezing or boiling

3. Add one cup of household bleach per gallon of water, mix well, and let sit for at least 10 minutes in the tank

4. Drain the tank and dispose of bleached water down the sink or toilet

5. Thoroughly disinfect (or replace) all gravel, pumps, filters, decorations and other items in the aquarium with a bleach solution (1 cup bleach/gallon of water), letting them soak for at least 10 minutes

Again, DO NOT pour tank water down sink drains or flush down the toilet without disinfecting it first. Do not dump untreated tank water anywhere near or into an outside water body, including storm drains.

A brief history of Zebra Mussels

• Zebra mussels are an invasive, fingernail-sized mollusk that is native to fresh waters in Eurasia. Their name comes from the dark, zig-zagged stripes on each shell.

• Zebra mussels probably arrived in the U.S. in the 1980s via ballast water that was discharged into the Great Lakes by large ships from Europe. They have since spread rapidly throughout many parts of the U.S but have NOT yet been found in Maine or New Hampshire

• Zebra mussels negatively impact aquatic ecosystems in many ways. Because they reproduce in very large numbers, they filter out enormous quantities of microscopic algae and other nutrients that native freshwater mussels, fish and other aquatic species need for food. They form dense beds attached to the bottom substrate and other hard surfaces, including the shells of native mussels - competing for space and even smothering native mussels and other bottom dwelling organisms by their sheer numbers.

• They also cause great economic harm by attaching to and clogging boat motors and hulls, docks, hydropower structures, intake pipes for water treatment and power generating plants, and other in-water structures, which can cost millions of dollars to remove and repair the damage. Their huge populations can also greatly reduce lakeshore property values.

• Zebra mussels are a restricted/prohibited species in Maine and New Hampshire.