Asian clams’ unfold in Columbia River warns of worse invaders

The invasive Asian clam is extra frequent within the decrease Columbia River than its native habitat of southeast Asia, based on a examine of the clam’s abundance within the river.

The findings do not bode nicely for potential future invasions by the much more harmful quagga and zebra mussels. To this point, the Columbia is among the solely main U.S. rivers to stay free of those infamous ecology-destroying, equipment-clogging bivalves.

To grasp how new invaders would possibly unfold, a Washington State College-led workforce studied the present invasive Asian clams hoping to see what would possibly restrict them. Sadly, the reply was—not a lot.

“What struck me was simply the sheer number of habitats that Asian clams had been in a position to quiet down in and survive,” stated Salvador Robb-Chavez, a current WSU grasp’s diploma graduate and the examine’s lead writer. “We discovered proof of their presence nearly all over the place within the decrease Columbia River.”

For this examine, printed in journal Worldwide Evaluate of Hydrobiology, the researchers sampled 27 websites alongside 481 kilometers (about 299 miles) of the river, stretching from the ocean to Richland, Washington. They discovered Asian clams had been in a position to stay at a wide range of temperatures, water high quality and substrates, equivalent to silt, sand or rock.

The workforce did discover higher abundance of Asian clams beneath the Bonneville Dam than above it, and their best focus, about 430 particular person clams per meter, was discovered on the Sandy River confluence in Gresham, Oregon. The clams tended to be extra prevalent in hotter waters and the place slope of the financial institution or stream mattress was much less steep or extra sandy, however few habitats had been solely devoid of Asian clams.

Thought of world invaders, Asian clams have been discovered on nearly each continent. The Pacific Northwest was one of many first locations they landed within the U.S., arriving within the Columbia River round 1938, presumably launched when a ship dumped its ballast water.

It takes only one Asian clam to begin an invasion, since they self-fertilize. The Asian clams have disrupted the Columbia River meals webs by consuming up plankton that native mussels and salmon prey additionally want. They trigger not solely ecological however financial injury as nicely since they ship plumes of larvae with mucus secretions that may clog up aquatic infrastructure.

Whereas presently the Columbia River has a regarding Asian clam inhabitants, different locations have much more, together with East Coast rivers and Lake Tahoe in California, Robb-Chavez stated.

And as dangerous as Asian clams may be, quagga and zebra mussels are worse. Whereas they do not self-fertilize, these bivalves nonetheless reproduce extraordinarily quickly. For instance, a feminine zebra mussel can launch as many as 40,000 eggs as much as 4 instances a 12 months. They’ve already prompted hundreds of thousands of {dollars} in injury within the Nice Lakes, by clogging water intakes and threatening native ecosystems.

The Columbia River has thus far averted an invasion from these mollusks which initially hail from Russia and Ukraine, however as a current scare of zebra mussel-infested moss balls offered for fish tanks reveals, it would require vigilance to maintain the river away from them.

“People are sometimes liable for spreading invasive species,” stated Robb-Chavez. “When you’re a boater, just remember to clear out your hull, maintain and trailer, based on Division of Fish and Wildlife tips. When you maintain fish as pets, watch out you are not by accident importing species with gadgets you utilize in your tank, and watch out the place you throw issues away.”

Along with Robb-Chavez, co-authors on this examine embrace his advising professor Stephen Bollens and Gretchen Rollwagen-Bollens of WSU Vancouver in addition to Timothy Counihan of the usG.S.