Daniel showed the pet store manager how to kill the freshwater intruder by soaking it in super salt water, and they removed the moss balls from the shelves. Yet on March 8, the USGS reported mussel sightings in foam balls in Alaska, California, Colorado, Florida, Georgia, Iowa, Massachusetts, Michigan, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, Tennessee, Vermont, Virginia, Wisconsin, Washington and Wyoming – with more states added since. Officials are investigating what Daniel calls the “chain of custody,” trying to determine whether the moss balls all came from a single producer, possibly a Ukraine-based wholesaler, or from multiple sources. Meanwhile, along with the US Fish and Wildlife Service and other partners, the USGS issued guidelines to put ham on the foam balls to crush the new invasion – this is where all the blanching, boiling, freezing and other punches come in. Then the brutalized ball should end up in the trash, in a sealed bag.
Introductions from home aquariums are not the most common vector for species that enter streams such as the Great Lakes, but “they do occur,” says Christine Mayer, an aquatic ecologist at the University of Toledo. “Especially with fish – people don’t want to kill them. People don’t feel so bad about putting a plant in the compost, but they’re not sure how to humanely euthanize a fish. Mayer says environmentalists who sample in the Great Lakes sometimes encounter a goldfish, either released from a fish bowl or descended from other fish that have gone wild.
A preemptive strike is the best way to maintain small populations of zebra mussels, as established communities are incredibly difficult to eradicate. “Everyone who works with invasive species says prevention is better than cure,” Mayer says. “It’s cheaper, easier, and better to keep things out of the way than trying to kill them once they’re there.”
Large vessel introductions are no longer a major problem, as there are now procedures for how, where and when ballast water can be dumped, says Eva Enders, a research scientist at Fisheries and Oceans Canada who studied the musculature of mussels in Lake Winnipeg, in Manitoba. Now, says Enders, “the remaining risk is inland – the transport by small pleasure craft or craft from lake to lake, river to river.” To help with prevention, conservationists, naturalists and others around the Great Lakes region have encouraged boaters to inspect their hulls and engines and empty and dry the compartments containing water between outings.
It’s hard to imagine a future in which mussel-steeped waterways will ever be completely free from them. “The Great Lakes are kind of… they’re already a thing,” Mayer says. This is not the case everywhere, however, and more recent efforts have focused on smothering invasive zebra mussels in the western United States, where they have not yet claimed so much land. Groups such as the Collaboration on invasive mussels, which works in partnership with the Great Lakes Commission, USGS, National Oceanic and Atmospheric Administration, and others, share tactics to smother small populations. In Lake George in New York, for example, a team successfully expelled a young population of mussels by quarantining the entire lake and sending divers to remove them manually.
Other strategies include pumping carbon dioxide into the water column, which suffocates the mussels inside, and lays tarpaulin-like benthic mats over mussel-strewn bottoms, barricading the creatures of oxygen, light and the food. Several states have “decontamination stations,” where boats are inspected and cleaned, Weibert says. In Alberta, Canada, mussel sniffer dogs are trotted at highway checkpoints, Enders notes. USGS staff are adapting a test, originally developed for invasive carp, to determine the genetic evidence of zebra mussels in water; Daniel thinks he could be up and running in the next few months.
But for now, environmentalists really need your help to prevent further spread – and that means unleashing hellish fury on mossballs.
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