‘Imminent threat’: Mussels invade California Delta for first time in North America

Based on its brilliant name, the golden mussel sounds like it might be California’s state clam.

Unfortunately, this creature’s only connection to the Golden State is the fact that it is the last invasive species found in California, and it is a bad species that can clog major water pipes.

On October 17, tiny freshwater clams that were already besieging the waterways of southern South America were discovered on Rough and Reedy Island, near Stockton. Since then, state officials say he has been in at least one other location, O’Neill-Forebay, in Merced County.

The sighting of the mussels in the Sacramento-San Joaquin Delta is the first confirmed sighting of the mussels in North America, according to a news release from the California Department of Fish and Wildlife.

It is possible that this is just the beginning of a long battle to slow its spread. Major concerns now include potential impacts on the environment and the Delta’s pumping stations, which supply water to 30 million people and millions of acres of farmland.

Unless it is contained and eradicated immediately, it may not be eradicated, according to UC Davis biologist Peter Moyle.

“If we’re lucky enough to make a real attempt to eradicate the virus in the area where it’s now found, it might not be too costly and it might be worth it,” he said.

But if such efforts fail, it could be a serious problem for native species that the mussels outcompete them for food.

The Department of Fish and Wildlife is already considering these worst-case scenarios.

“This species poses a serious, immediate threat to the ecological health of the Delta and all state waters, water transportation systems, infrastructure, and water quality,” the campaign wrote.

The Department of Water Resources is already inspecting vessels in hopes of preventing the spread of mussels. At the San Luis State Recreation Area, officials are checking watercraft coming out of O’Neill Forebay, San Luis Reservoir and Los Banos Creek, said Tanya Veldhuizen, manager of the department’s special projects division. The inspections are intended to “ensure that all water is drained from wells and holds to prevent the spread of invasive species to other bodies of water.”

The department is also taking enhanced measures to protect the State Water Project, a system of pumps, pipes and canals that export water south from the Delta, she said. Increased vigilance to prevent “mussel biofouling” requires more frequent inspections, as well as cleaning and flushing, she said. She said mussels are likely to accumulate in grates, strainers and trash cans.

Native to China and Southeast Asia, golden mussel – taxonomically Limnoperna fortune – attaches to underwater surfaces, forming thick “reefs” made up of millions of animals. They feed by filtering nutrients and plankton from the water, and through this passive action they can have devastating effects. Essentially, they filter nutrients from the local food web. In Argentina and southern Brazil, where golden mussels arrived in the 1990s, they have crowded out other species and smothered river beaches and native vegetation. Scientists have watched them spread north at a rate of 150 miles a year, and they fear the invaders will find their way into the world’s largest river system and Earth’s hottest biodiversity hotspot – the Amazon Basin.

They also wreaked havoc on underwater infrastructure, from hydroelectric dams to water supply systems. For example, mussels have reportedly clogged the intake pipes of the municipal water supply system on Brazil’s Lake Guaiba.

No one can be sure how the mussels got to California, but sources suspect they arrived the same way they are believed to have arrived in South America – in the bowels of commercial ships, where ballast water used to stabilize ships is often dumped. sea. port of arrival.

Not everyone is particularly surprised either. Moyle, for example, said he has been waiting for the golden mussel to arrive in the state for years. The California Delta, he noted, is considered one of the most populated estuaries in the world. It was colonized at least 185 foreign species, from Himalayan blackberries and fig trees to black bass, striped bass and water hyacinth. One estimate is that invasive species are responsible for astonishing 95% or more of the total biomass of the estuary.. Nutria, a large, water-loving rodent native to South America, has spread across the estuary in recent years amid concerns that it could, among other things, damage dams with its burrows.

Even Asian bivalves already live in the bay and delta. Eurasian clamfor example, spread along a waterway in the 1980s. Biologists say the species likely played a role in the demise of native fish by consuming the tiny food particles on which they depend. For example, the failed discovery of Delta smelt was associated with the spread of these shellfish.

Now scientists fear that golden mussels may be exacerbating this pressure.

But not necessarily. Moyle said the Delta has already been so badly damaged and its food resources already in demand by other species, especially filter-feeding clams, that golden mussels may not have room to move.

“Aggressive clams occupy a lot of niche,” he said.

On the other hand, Moyle said, “it could be a super-invader”—an invasive species so adaptive and resilient that it replaces other invaders that came before it. The delta’s average temperature and salinity range is ideal for golden mussels, he said.

But in this ecologically plundered In a place like the Delta, not everyone is worried about the next bump in the road. Brett Baker, a water resources attorney for the Central Delta Water Agency, a sixth-generation Sutter Island resident and former Moyle biology student, isn’t concerned about the golden mussel’s appearance.

“All my life I’ve heard concerns about quagga mussels, zebra mussels, mitten crabs and nutria,” he said. “I just don’t think there’s enough slack in the system or enough room for niches, especially for a species that hasn’t adapted to live here… I’m pretty sure in 20 years we won’t be talking about the golden mussel. , but I could be wrong.”