It’s a threat across the country including smaller coastal rivers such as California’s San Lorenzo. The river travels only 30 miles from 2500 feet in coastal mountains before emptying into the Pacific Ocean at Monterey Bay [wiki]
Mud snails gobble up the same bacteria and algae that sustain flies and river insects, reducing the food available for native fish. If they overwhelm a watershed, mud snails can displace 95 percent of the bugs and invertebrates!
In New Zealand, the snails are preyed upon by 3 kinds of fish and 14 species of worms. But in California, there’s no predator capable of extracting them from their shells. The snails snap shut to pass through ducks and fish virtually unharmed.
The snail is here.
Only changing people can rescue some rivers. People can help the remaining fish survive. For example, there’s only a few thousand fish surviving in the San Lorenzo. The overall health of streams and rivers has become critical. There’s no question we must reduce Army Corp-style flood engineering, erosion from construction, power plants, public works and road repair, plus increase control of litter and toxics.
Humans slap shut too
South along the California coast is another of America’s most endangered smaller rivers flowing into Monterey Bay. The Pajaro River is a disaster as well. Old-fashioned industrialization is killing it.
Slow as snails, lazy institutions are failing to deal with the watershed’s problems.
While many farmers are learning to support biology and the environment, the Pajaro River has been slapped with erosion and concrete over decades and there’s a new tussle with the Army Corps’ plan to spend $200million merely to chop vegetation and raise levees rather than secure the river’s health.
Before the Golden Gate appeared as a geologic exit, all the waters of the San Francisco Bay and the San Joaquin Delta flowed over this area – through the Chittenden Gap and into the Pajaro River Watershed before reaching the Pacific at Monterey Bay.