A highly invasive, exceptionally adaptable threat, typically measuring a single inch in length, is heading to the Amazon River Basin — if, indeed, it hasn't already arrived.
Native to China, the golden mussel made its remarkable journey to Argentina in the early 1990s, surviving in the ballast water that ships carry to help remain steady. The bivalve quickly populated the rocks of the La Plata River in Argentina, ballooning from five organisms per square meter in 1991 to 30,000 a year later, nearly tripling to 82,000 in 1993, and reaching an incredible 150,000 by 2002.
Soon, Limnoperna fortunei was detected in Uruguay, Paraguay, Bolivia, and Brazil, and has now crept within 1,200 miles of the Amazon River Basin, home to the world's largest number of freshwater fish species.
According to the University of Buenos Aires' Demetrio Boltovskoy, who has studied the golden mussel for 20 years, it's only a matter of time before it's spotted in the basin.
"We've been expecting it to be there for quite a few years now. It hasn't been reported yet, but that doesn't mean it's not there," Boltovskoy told VICE News, stressing how huge and, in some parts, largely unmonitored the area is. "It's inevitable."
The mussel's flexibility is the key to its prowess for inhabiting ecosystems far from its home. Capable of withstanding a high degree of variability in water temperature, salinity levels, and acidity, their numbers can quickly explode, causing toxic algal blooms, which can lead to widespread aquatic die-offs.
It's not only the environment that's at risk. The bivalve can also cause big problems for aquatic industry — of particular concern to a country that gets more than 80 percent of its electricity from dams. The mussels clog pipes at power plants, industrial facilities, and water treatment centers, resulting in annual, million-dollar cleaning bills. Don't expect strainers or screens to do the job; while they can filter out adult mussels, the larvae pass right through.
Mauro Rebelo, a scientist and professor at the Federal University of Rio de Janeiro, said the basin is lucky to have held off invasion this long.
"There is a huge risk to the Amazon Basin and, in a way, I'm surprised it's not there yet," Rebelo told VICE News. "The flexibility is related to the genes the mussel has, and which genes governs this flexibility is one of the questions we're trying to answer."
He's hinting at a promising solution underway, spearheaded by Marcela Uliano da Silva of Federal University. Da Silva crowd funded $20,000 to map the mussel's genome, in the hopes of discovering how to switch off the mussel's survival genes.
'They mate much more than they sleep and they eat even more.'
"The mussels took the saying 'grow and reproduce' too seriously. They grow side-by-side, one under the other, they grow, grow, grow," she explains in an animated short for her crowd funding campaign. "Without natural predators, they're well-adapted to the tropical climate. Now, they only do three things: eat, sleep, and mate — not necessarily in that order. They mate much more than they sleep and they eat even more."
According to Silva, genome sequencing could take four years, which Rebelo, who is da Silva's academic advisor, said was "very optimistic." But, he told VICE News: "I strongly believe that gene silencing is the way to go, not to just put more poison in the water."
Success sequencing the golden mussel could mean relief from other invaders, too, first and foremost the zebra mussel — a pest which costs the United States power industry up to $60 million a year.
Efforts to control the mussel in Brazil have focused on public awareness, like Brazilian power company Furnas's campaign "Don't Let The Golden Mussel Hitchhike." It warns fishermen of the high risk of unintentionally transporting the resilient bivalve to new areas. The government has also imposed regulations controlling the disposal of ballast water.
Attempts to kill the mussel with chemicals carry environmental risks and aren't guaranteed to solve the problem. The mussels can sense the toxicants in the water and slam their valves shut, remaining in a high-stakes game of hide-and-seek for weeks at a time. Completely outside of the water, the mussels have lived for more than two weeks in a researcher's bucket, perhaps unsurprising for a creature that can even handle being gobbled up, surviving in the digestive tract of fishes.
"I think the solution is to learn to live with the mussel, and get used to it and try to fight it in plants, in industrial plants, in power plants, where it's truly powerful," Boltovskoy told VICE News. "In the wild, we have lost the battle."
Follow Darren Ankrom on Twitter: @darrenankrom