Biologist, volunteers work on mussel relocation project

Only his hat, part of his back and a snorkeling tube appeared above the cold water as Mason Bindl of the Lake Tahoe Basin Management Unit searched for mussels that would be used as part of a pilot project that will relocate roughly 900 mussels.

The mussels gathered were then sized, weighed, and numbered.

Bindl’s cold dive came as part of an effort to find a suitable home for a native species of mussels called western pearlshell mussel found in the Upper Truckee river, not to be confused with notoriously considered invasive and non-native mussels such as the quagga mussel and the zebra mussel.

The project, conducted by biologists and volunteers, aims to save the western pearlshell mussel from a channeling project that is set to improve the local ecosystem but will dry out the area the mussels currently live on.

If the pilot project is successful, the group will eventually relocate between 10,000 and 12,000 mussels once an ideal location -- or several ideal locations -- is found.

“Habitat is kind of limited, especially for that amount of mussels,” Sarah Muskopf said, an aquatic biologist with the LTBMU.

The project comes in preparation for the 2016 re-channeling project that will dewater the area where the mussels currently live.

“We’re lucky that we get to have that adaptive management opportunity because some people who don’t get this amount of time would have to move all 12,000 and then you could still have 90 percent failure,” Muskopf said.

The re-channeling project aims to deviate from certain areas of the river where it has gotten too wide and shallow after erosion occurred, LTBMU hydrologist Theresa Cody said. The erosion and other factors affecting the current river path have affected the ecosystem and are also increasing the amount of sediment flowing into Lake Tahoe.

If left where they are, the mussels would die, but it is unclear whether the mussels, which have a roughly 100-year life span, would be able to live much longer even if the rechanneling project did not take place and they were left where they are.

“It could turn out that this population is not reproducing, and it could have been a bad situation either way,” Bindl said. “This mussel may have been endangered with the way that this channel is now.”

One major factor that could affect the mussels, LTBMU biological science technician Erin Miller said, is the decrease in population of cutthroat trout in the river, presumably caused by the lack of gravel crucial to their environment as part of the effects of erosion. The trout, Miller said, are crucial to the mussel’s reproduction, as they serve as a transportation agent for DNA.

The western pearshell mussel is a filter feeder, Miller said. They filter out nutrients, contaminants and suspended matter in the water and can help clean water bodies.

“There actually have been some studies lately on this specific species in using them to clean up and improve water quality,” Miller said.

As part of the project, which is a collaborated effort with the Nature Conservancy, the Tahoe Regional Planning Agency, California Department of Fish and Wildlife and the University of Reno, the biologists and volunteers are collecting, sizing, weighing and numbering individual mussels before they are introduced to a new environment. The group will then monitor the mussels individually and determine whether they are growing and gaining weight, which may indicate if a given environment is suitable for the species.

“We’re hoping, because we’re looking at so much in the study pots, that if there’s something that is triggering lack of success, we’ll be able to identify it. We’re moving them to such different type habitats that we can really eliminate some things,” Muskopf said.

The group is testing a varied sample of mussels that includes different weights and sizes, as well as several different environments.

“Some sites we are moving them to areas a little bit down stream. Some sites we are moving them to are in Christmas Valley. We’re also moving them into Trout Creek. Trout Creek is a different system in that the water is a little bit colder, it’s a little bit smaller stream and a little bit more shaded, and so, we’re going to evaluate whether that is a viable relocation site,” Miller said.

“We’re testing out different environmental variables in what we call a micro-habitat scale. So, (we’re testing) stream shade, substrate, velocity, temperature, algae and food sources, a ton of different variables go into where these mussels live,” she added.

Because of the amount of time the group has, and because of the way the project is progressing, Miller said there is a good chance the project will find success.

“I think with the way that this study is set up, in that we are actually doing research to figure out what the best place is to put them, I’m pretty optimistic we’ll find a really suitable habitat for the 10,000. We may lose a few here and there in the beginning of the process, but I think that overall we’re going to have success,” Miller said.