AIS Sampling Ends for the Season - No Mussels Detected

With snow coming early this year, the 2017 aquatic invasive species sampling wrapped up at the end of October. Clearwater Resource Council AIS Specialist Joann Wallenburn, field technician Swan Valley Connections' Caitlin Mitchell and Blackfoot Challenge project leader Jennifer Schonnen led the sampling efforts this year with the help of volunteers from the Blackfoot, Clearwater and Swan Valleys. To date, there has been no evidence of zebra mussels, Eurasian milfoil or Curly Leaf Pond Weed in area waters.

Since 2009, six lakes in the Clearwater were monitored: Lake Alva, Lake Inez, Seeley Lake, Salmon Lake, Placid Lake and Big Sky Lake. Initially the only sampling method was microscopy where the lab looked for mussel larvae called veligers under a microscope.

The technology was developed to allow scientists to use eDNA detection for mussels. CRC started sending samples for eDNA analysis of the six lakes in 2013.

After Canyon Ferry and Tiber Reservoir tested positive for veligers last fall, the Blackfoot Challenge and Swan Valley Connections wanted to employ the same sampling program in the Blackfoot and Swan Valleys. They joined with CRC and submitted a joint grant request through the Missoula County Weed District to Montana Department of Natural Resources and Conservation to expand microscopy sampling to the middle Blackfoot, the Clearwater and Swan Valley. Lindbergh, Holland, Swan, Van, Coopers, Browns and Upsata Lakes were sampled once a month from May through October.

Most of the lakes were also sampled for mussel eDNA in May, August and October. The Swan Valley lakes and Big Sky Lake were only processed for eDNA in August. The August samples also included the eDNA testing for Eurasian milfoil and Curly Leaf Pond Weed.

The Lolo and Flathead National Forests, US Fish and Wildlife Service and the Placid Lake and Big Sky Lake homeowners associations funded the eDNA sampling efforts depending on the landownership surrounding the body of water.

When sampling for eDNA all the equipment was bleached prior to sampling to ensure elimination (killing) of everything to which the equipment had been exposed. Those doing the sampling also wear surgical gloves while taking and processing the sample to prevent contamination of the sample.

Wallenburn said the strongest eDNA signal is observed in the late fall which is why samples were taken as late in October as possible with the pending snow.

"eDNA analysis technology is currently being developed at the Flathead BioStation to increase our ability for early detection of the mussels," wrote Mitchell in an email. "The earlier we can detect them, the better chances of containment, we hope."

Mitchell was the shared field technician with CRC, the Blackfoot Challenge and SVC that helped ensure consistency across the watersheds and increased efficiency in getting the samples processed and gathered for delivery to Montana Fish, Wildlife & Parks lab in Helena and the Environmental Genetics Lab in Missoula.

Since none of the organizations own motorboats to take the samples, all three organizations relied heavily on boater volunteers. Wallenburn continued to utilize her trained citizen scientists on Big Sky Lake, Placid Lake, Lake Inez and Lake Alva.

"We were able to recruit very dedicated and enthusiastic volunteers that took us out once a month," wrote Mitchell.

Wallenburn said she was able to get special permission from the Rice Ridge Fire Incident Management Team with the help of Game Warden Bill Koppen to do the August sampling on Seeley Lake even when the waters were closed due to fire suppression activities. The August sampling was critical because it was the only time they did the eDNA samples for the AIS plant species.

"The agencies still worked to cooperate to make things happen that needed to happen even though this fire was going on," said Wallenburn.

The Potomac School Explorers Club with students from first through seventh grade was able to help with the October sampling on Holland Lake. This fulfilled the outreach component of the DNRC grant. Four students helped with the sampling from Bill Beers' boat.

The students also walked Holland Creek learning about the animals and plants that inhabit it, learned about the native microfauna in the water and how the samples are processed in the water and participated in activities focused on food webs and food chains and how AIS will affect that.

"I think it would be great to get the schools involved and students out on the water," wrote Mitchell. "The constraints to doing that will be in whether our volunteers are comfortable with it, if there's enough room on the boat for the number of kids and if schedules can work out. The key there would be keeping [the students] engaged while making sure they help get a good, accurate sample."

Mitchell wrote there have been no signs of mussels to date in the Blackfoot, Clearwater or Swan Valleys. Samples are being processed as quickly as possibly but the analysis likely won't be complete for the area lakes until the winter months.

Sampling will continue as long as there is funding.

"We have to be vigilant. Until there is new methodology to detect them or we come up with the silver bullet cure, we will need to continue AIS monitoring," said Wallenburn.

Wallenburn said the sampling strategy that they have developed is focusing on hot spots for introduction including the lake inlets, outlets, boat launches and marinas. They also target areas for AIS plant sampling in the lakes where native vegetation thrives.

However the sampling protocol is still evolving for the microscopy and eDNA. Questions that are still unanswered are how often do lakes need to be sampled for early detection and how many sites are needed to be confident that if mussels exist they would be detected.

"Not only do you need to have the introduction of the organism but you also have to have suitable growing conditions for a colony to establish," said Wallenburn. "Our rocky bottoms are ideal."