Golden Mussels Threaten the Amazon, What's to be Done?

The Amazon River has long been a symbol of nature's pristine balance - a powerful rush of water carving its way through dense forests full of live. However, these days that river is in danger, but not by man or machine. Instead, its biggest threat is a tiny freshwater mussel.

Since hitching its way from Chinese waters in the early 1990s, the golden mussel (Limnoperna fortunei) has earned a great deal of infamy as a hardy and fast-spreading invasive species. And while many invasive species will simply compete for resources and disrupt ecosystems, this mussel does something far more destructive.

Experts are quick to classify the golden mussel as an "ecosystem engineer" because it alters the nature of the sediment it sits in, filtering key nutrients out of the water while simultaneously making surrounding sediment richer with it feces. The result is a tip in ecosystem balance, in which local gastropods, leeches, and aquatic insects explode in number even while the invaded waters are sapped of their oxygen.

Much like the aggressively invasive zebra mussel in the United States and the menacing quagga in the United Kingdom, these mussels also can also clog pipes in hydroelectric plants. They also piggyback onto large local clam species, sealing these mollusks shut and starving them to death.

According to a report published back in May, the golden mussel is already costing South American communities an estimated $20,000 (USD) a day in various ecological and industrial losses.

And these invaders, The Associated Press (AP) explains, have made their way into the Pantanal wetlands system in western Brazil. This region is a mere 1,200 miles from waterways that lead to the Amazon River directly, which is worrying experts.

"You clearly want to keep these out of the Amazon because if they were to get in, the potential consequences are very significant," Hugh MacIsaac, an invasive aquatic species expert at the University of Windsor, in Ontario, Canada, explained to the AP. (Scroll to read on...)

But how do you keep them out? Marcela Uliano da Silva, a 27-year-old Brazilian biologist, is arguing that the easiest and most effective way is to utterly eradicate the species from the continent. And the best way to do that, she recently told National Geographic, is to turn off the genes that make it hardy.

As seen in some experimental mosquito control programs, Uliano da Silva's approach would require the introduction of genetically modified mussels that have had certain genes silenced that are key to long term survival or reproduction. These modified mussels would then breed into the invasive population, ensuring that more of the population in each generation also boasts genes for a lower survival rate.

And while researchers working with modified mosquitoes have struggled with ways to ensure that they do not eradicate the insects entirely, the golden mussel is no essential local.

Current strategies for keeping the mussel out of the Amazon include widespread education, inspections, and regulation - such as requiring fishermen and other ships to empty their ballast before heading onto the river. In this way, the chance of an unwelcome hitchhiker making it to the Amazon is reduced.

However, if the golden mussel could be weakened over the course of a few generations, then, Uliano da Silva argues, local ecosystems could take care of the rest by bullying the invader straight out of South America.

But while that sounds like a great idea, other experts are hesitant to agree.

"We know that evolution does not stop," James Collins, an evolutionary biologist at Arizona State University, who has also been investigating genetic approaches to invasive control, explained to National Geographic last year.

He expressed concern that too much manipulation could lead to unforeseen consequences, and thus, the species should be carefully and extensively studied before action is taken.

"We haven't drawn the lines through the dots," Collins said. "But it looks like you can draw the lines through the dots, so now is the time to think about the implications of this technology."

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