Killer Shrimp Hitching Rides Across UK by Canoe
National Park Service
Jan. 17, 2013 -- The invasion of Burmese pythons in Florida's wetlands poses an existential challenge to the state's native wildlife as these apex predators have been known to prey on everything from small animals like raccoons and opossums to larger ones like white-tail deer and even alligators.
How has the state faced the challenge of dealing with 150,000 non-native snake threatening its biodiversity? The answer is a good old-fashioned hunting contest, of course. Florida's "Python Challenge" has drawn some 800 snake hunters, according to a report by the Associated Press. Most of the snake hunters are amateurs, so they're given some instruction: "Drink water, wear sunscreen, don’t get bitten by anything and don’t shoot anyone."
Good advice. But can the state of Florida really shoot itself out of this mess?
State of Louisiana Department of Wildlife and Fisheries
Invasive species might be bad for the environment, but many of them are good enough to eat.
Tiger prawns in the Gulf, Asian carp in the Great Lakes and many other species have been put on the menu in their respective locales in an attempt to thin their numbers.
In fact, there are even books devoted to taking advantage of the potential of using invasive species as a potential food source.
Sometimes, nature will take care of a problem all on its own.
A study published in 2010 in the Journal of Arid Environments sought to document invasive bullfrog populations in the mountains of Mexico's Baja California. To their surprise, the invaders were actually put under severe pressure due to flash floods that occurred periodically in the region that they simply weren't adapted to cope with.
The bullfrogs happen to breed during the hurricane season, making them vulnerable to population swings. Native frogs, on the other hand, fared just fine circumstances they were adapted for.
Just as the environment can help push out an invasive species, so too can a well adapted native on rare occasions.
A University of Georgia study conducted in 2012 found that some native clearweed plants in the Peach State have evolved resistance to garlic mustard, an invasive plant first introduced 150 years ago to the United States from Europe.
The garlic mustard, a noxious plant that spreads rapidly, is evolving a counter-resistance, setting off a kind of chemical warfare among the native and invasive species.
David Pattermore/Princeton University
In some cases, the best policy for dealing with invasive species is just to leave them alone, particularly if they occupy a crucial ecological niche that they or other invasive plants and animals forced another species to vacate.
A study by Princeton researchers in 2011 found that invasive ship rats brought to New Zealand's North Island when Europeans first arrived devastated local populations of birds and bats. As pollinators, the native species were an important part of the ecosystem, but the ship rats have filled that role. As one of the researchers explained in a press release, "the killer stepped in to do the job of its victim."
Furthermore, efforts to eradicate the invader could come at a cost to native species.
Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA SCS
One common tactic for reducing populations of invasive species is simply to make their importing them from their native habitat illegal.
State fish and wildlife departments monitor the potential introduction of invasive plants and animals from outside their jurisdictions. Alligatorweed, for example, is an invasive aquatic plant that originated in South America and can not only endanger native species, but also put humans at risk by reducing water quality.
Unfortunately, that tactic doesn't seem to have its limitations. Florida, after all, eventually made it illegal to import Burmese pythons, but that hasn't stopped in the increasing numbers of these snakes in the Sunshine State.
Invasive species such as the killer shrimp, zebra mussel and American signal crayfish may be traveling from waterway to waterway throughout Britain in canoes and fishermen's waders.
A survey of 1,500 outdoor enthusiasts published in PLoS ONE shows that most aren't taking precautions to avoid transporting invasive species.
More than half of anglers and nearly 80 percent of canoeists surveyed visited more than one waterway within two weeks. If their equipment isn't properly cleaned and dried between water activities, invasive species can easily hitch a ride. Killer shrimp can survive in damp gear, even in a fold of a wetsuit, for up to 15 days, said study co-author Alison Dunn of the University of Leeds in a release.
“Once it gets into the new water system, it is voracious,” she said of the shrimp species. “It will take bites out of things and leave them uneaten, killing when it doesn't need to eat.”
Attempting to curb the spread of invasive species, the British government launched a “Check, Clean, Dry” campaign in 2011 to encourage water sports enthusiasts to examine and thoroughly dry their equipment.
Prevention is the best way to contain these destructive animals, said study lead author Lucy Anderson, also of the University of Leeds, in a release: “Once invasive species establish in rivers and lakes, they're almost impossible to eradicate.”
But Anderson and her colleagues show that many of Britain’s more than 4 million anglers and 400,000 boat owners aren't following that advice. Half of the canoeists and 12 percent of the anglers surveyed do not clean or dry their equipment between trips.
When traveling outside the United Kingdom, 8 percent of anglers and 28 percent of canoeists surveyed failed to clean or dry their gear after international trips, potentially transporting invasive species across borders.
Photo: Killer shrimp (Dikerogammarus villosus) travel from waterway to waterway throughout Britain. Credit: The Environment Agency