Newswise — VANCOUVER, Wash. –According to a study on the clam's prevalence in the river, the Asian clam, which is invasive, is found in greater numbers in the lower Columbia River compared to its original habitat in southeast Asia.
The outcomes do not augur favorably for prospective future incursions from the even more damaging quagga and zebra mussels. Up until now, the Columbia River stands as one of the sole significant rivers in the United States that has managed to evade these notorious bivalves, which wreak havoc on ecosystems and obstruct equipment.
In an attempt to comprehend the potential spread of new invaders, a team led by Washington State University conducted a study on the prevailing invasive Asian clams, with the hope of identifying potential constraints. Regrettably, the findings revealed that there were few limiting factors observed.
"The aspect that left a profound impression on me was the astonishing range of habitats in which the Asian clams were capable of establishing themselves and thriving," remarked Salvador Robb-Chavez, the lead author of the study and a recent graduate with a master's degree from WSU. "We discovered signs of their existence practically everywhere in the lower Columbia River."
In the study, which was published in the International Review of Hydrobiology, the researchers conducted sampling at 27 locations spanning a distance of 481 kilometers (approximately 299 miles) along the river, extending from the ocean to Richland, Washington. The findings revealed that Asian clams exhibited the ability to thrive across a diverse range of conditions, including different temperatures, water quality, and substrates such as silt, sand, or rock.
The team observed a higher density of Asian clams below the Bonneville Dam compared to above it. The highest concentration of these clams, with approximately 430 individuals per meter, was discovered at the confluence of the Sandy River in Gresham, Oregon. The clams displayed a greater prevalence in warmer water and in areas where the slope of the bank or stream bed was less steep or more sandy. However, it was rare to find habitats completely devoid of Asian clams, as they were present in varying degrees across the studied locations.
Recognized as global invaders, Asian clams have been discovered on nearly every continent. The Pacific Northwest emerged as one of their initial destinations in the United States, as they were introduced to the Columbia River around 1938, likely through the release of ballast water by a ship.
The ability of Asian clams to self-fertilize means that just one individual is enough to initiate an invasion. These clams have caused significant disruption to the food webs of the Columbia River by consuming plankton that are crucial for native mussels and salmon, which rely on them as a food source. In addition to ecological impacts, Asian clams also pose economic challenges. They release larvae along with mucus secretions, forming plumes that can obstruct aquatic infrastructure, leading to potential damage and maintenance costs.
According to Robb-Chavez, although the Asian clam population in the Columbia River is a cause for concern, there are other locations where their abundance is even higher. This includes various rivers along the East Coast and Lake Tahoe in California, where the presence of Asian clams is more pronounced.
Indeed, quagga and zebra mussels pose an even greater threat compared to Asian clams. Although they do not possess the ability to self-fertilize, these bivalves reproduce at an alarming rate. A female zebra mussel, for instance, can release up to 40,000 eggs as many as four times in a year. Their reproductive capacity contributes to their rapid population growth. These mussels have already inflicted extensive economic damage in the Great Lakes region, where they have clogged water intakes and posed a significant risk to native ecosystems. The financial costs associated with mitigating their impact amount to millions of dollars.
Up until now, the Columbia River has managed to evade an infiltration by these mollusks, originally originating from Russia and Ukraine. However, a recent alarm caused by zebra mussel-infested moss balls being sold for fish tanks indicates that maintaining a clear river will demand constant watchfulness.
According to Robb-Chavez, humans frequently play a role in the dissemination of invasive species. He advises boaters to diligently follow the Department of Fish and Wildlife guidelines by thoroughly cleaning their hulls, holds, and trailers. For individuals who keep fish as pets, he urges caution to prevent inadvertently introducing species through tank-related items. Additionally, he emphasizes the importance of being mindful when disposing of objects to avoid unintended consequences.
The study cited in the previous statement was conducted by a team of researchers that included Robb-Chavez, his advising professor Stephen Bollens, Gretchen Rollwagen-Bollens from WSU Vancouver, and Timothy Counihan from the U.S. Geological Survey (USGS). The research received backing from the Washington State Lake Protection Association.
RSS