Tahoe's tiny bottom-dwelling invertebrates are vanishing at rates of 80 to 99 percent
Some of the tiny critters living on the bottom of Lake Tahoe's shallows are disappearing at an alarming rate and the danger could extend to newly discovered animals as well, scientists said Monday.
A week before researchers, land managers and politicians convene for the annual Lake Tahoe Summit, scientists from University of Nevada, Reno and the Desert Research Institute gathered on the shores of Incline Village to highlight recent work, including a newly discovered threat to native macro invertebrates living on the lake bottom.
These are fingernail-sized creatures such as stoneflies, worms and bottom shrimp and in places, their population is crashing. Numbers have dropped between 80 and 99 percent from levels recorded in the 1960s.
"They are disappearing. It's unprecedented. It's absolutely dramatic," said Sudeep Chandra, a fresh water science expert at UNR.
"There is a strong possibility we will lose these species in the future," Chandra said.
The dramatic drop in native invertebrate populations was discovered during routine bottom sampling and came as a complete surprise, Chandra said. He and colleagues had no reason to suspect the population crash was occurring.
Exactly why it's happening is unknown. One possibility is that the aquatic plants the animals need for habitat are declining, possibly due to a loss in water clarity experienced in recent years in Tahoe's shallow, near-shore environment. Another is that those same plants are being consumed by non-native species such as crayfish grazing on the lake bottom. Crayfish may also be eating the tiny animals.
"We think it's likely both ...