By EMILY SCHABACKER and SAMANTHA SUNDLY/Montana State News
On the shores of Tiber and Canyon Ferry reservoirs in northern Montana, adult zebra mussels threaten indigenous aquatic life as of Fall of 2016. Without any natural predators in the region, zebra mussels threaten aquatic ecosystems and cause damage to man made hydropower systems.
After the discovery of invasive mussel larvae, known as veligers, in Tiber and Canyon Ferry Reservoirs in November, Gov. Steve Bullock declared a natural resources emergency, according to the Billings Gazette. This order provides state access to $750,000 in emergency funds to begin the eradication process.
Zebra mussels found in North America, typically indigenous to European regions, survive in waters with unusually low calcium levels, according to the United States Geological Survey. The mussels require calcium in order to transform from veligers to shellfish.
Calcium concentration is a key factor in mussel distribution, according to Andrew N. Cohen and Anne Weinstein, authors of Zebra Mussel’s Calcium Threshold and Implications for its Potential Distribution in North America. Zebra mussels in North America have been known to initiate shell growth in 10 milligrams of calcium per liter.
The figure below, taken from Mineral and Water Resources of Montana, depicts the types of dissolved solids throughout the water systems in the state. According to the figure, more than half of the state is susceptible to zebra mussel infestation.
The figure shows the regions of the state that contain certain sediments in the waterways.
A 2015 annual watercraft inspection report listed five cases of zebra mussel contamination, three of which were found in Hardin, Montana. According to the report, about 27 percent of the inspected boats came from out of state.
The most recent discovery of zebra mussels at Fort Peck Reservoir in August 2016 were transported to Montana in a boat purchased in Michigan and taken for a test run in an infested lake, according to Montana Fish, Wildlife and Parks. Michigan reported the first infestation of zebra mussels in North America in 1988 and have struggled to manage the population ever since. The species is often transported to surrounding bodies of water on nonresident watercrafts.
With the detection of mussel veligers, scientists predict that the mussels have been present for greater than one year in Tiber Reservoir, according to Adam Sepulveda with the USGS. However, researchers are unable to predict the population of zebra mussels in Tiber Reservoir.
In 2015, just before inspectors discovered veligers in Tiber Reservoir, central Montana made $130 million in gas and diesel costs by nonresident visitors, according to University of Montana’s Institution for Tourism and Recreation Research and about $55 million in hospitality.
Central Montana, where Tiber Reservoir is located, made $130 millions on gas and diesel from nonresident visitors, indicating heavy tourism in the area.
The University of Montana’s Institution for Tourism and Recreation Research also surveyed over 300 nonresident Montana visitors in 2015 and 2016 that visited Chester, Montana, one of the closest towns to Tiber Reservoir. In 2015, 15 percent of the 170 non-resident visitors who took the survey participated in water-related activities, including river rafting, floating, canoeing, kayaking, and fishing.
In addition to the ecological problems, zebra mussels have a significant impact on the socioeconomic state of Montana. With evidence of mussels in one reservoir and suspect in two other bodies of water, the state already faces eradication and prevention costs of up to $10 million, according to the Montana Mussel Response.
Mussels attach to and damage hydropower structures and irrigation power structures, according to Sepulveda.
“The biggest fear is that mussels will get into the Columbia River Basin…that is chock full of hydropower dams,” said Sepulveda.
According to the Billings Gazette, Montana’s invasive mussel response team is asking the Legislature for $5.1 million in 2017 to increase the number of boat inspection stations and decontamination stations in Montana, specifically around the Tiber and Canyon Ferry reservoir areas.
Thus far, the state is focusing funding on early detection programs. With early detection of invasive species, eradication costs will likely be cheaper and will add preventative measures to the spreading of the species.
The Montana Mussel Response team has proposed several recommendations for how to handle the contamination, including a watercraft inspection program expansion, increasing the number of inspection stations in Montana from 17 to 34 by June 30, 2019.
Researchers are still looking for a means of effective and safe eradication of the species, but very few eradication methods exist at the moment, according to John Grassy, the acting public information officer for the Montana Mussel Response.
“It’s more of a behavioral change that needs to happen. We need to get people proactive. Boaters need to clean their boats and have them inspected regularly,” said Grassy. This will prevent the spread of invasive aquatic species throughout the state.