A deadly fungus could threaten several species of amphibians in the Tongass National Forest. On Mitkof Island, the US Forest Service uses a mix of old and new methods to find him.
About 3 miles inland, the Twin Creek Ski Hut overlooks a pond in the middle of the muskeg. Just a few weeks ago this part of the island was still covered in snow. Members of the Forest Service are there to look for frogs.
They draw buckets of water from different parts of the pond. Next, Marcee Meinhardt pours the water into a pump that transports it through a filter.
“This filter collects all of the environmental DNA,” Meinhardt said. “Then we’ll take a sanitary tweezer and collect the filter from the inside here, put it in a sanitary bag, label it with where we are and how much water was sent there, and then we will send it back to the lab. . “
The filters look like round cottons. They send about three dozen of them to a lab for DNA testing.
The results will tell them two things. First, if there are amphibians at the sites. And second, if pathogens like chytrid fungus are also present.
Chytrid is a skin fungus. Frogs and salamanders absorb oxygen through their skin, and the fungus hinders their ability to do so. This lowers their energy level and often kills them.
Last year, the Tongass Wildlife and Fisheries Program detected chytrid in Wrangell, Prince of Wales Island and Yakutat.
“It keeps them from reproducing or if they do, if they are able to reproduce, then generally this youngster will not be able to reproduce,” Meinhardt said. “It kind of cuts their genetic timeline in the bud.”
One in 16 amphibian species has become extirpated or endangered due to the chytrid fungus, according to a 2019 study. Global trade is believed to have brought it to Alaska from other parts of the world.
There are three species of frogs and three species of salamanders native to the Tongass. The forest service says they are an essential part of the food chain. They eat a range of insects and other invertebrates. And they are the prey of many fish, birds and small mammals.
Eric Castro is the fish biologist for the Petersburg Ranger District and is leading chytrid research efforts on Mitkof Island. He says the agency has very little basic information on the size and location of existing amphibian populations.
“If we don’t know how many there are, all we have is anecdotal evidence,” Castro said. “People say they saw more frogs in this area when they were young, but there is no data. So right now we are collecting data so that we can actually see what the impacts are and then assess the future of the species.
To collect this data, Castro and his team visited twelve different sites, twice each. While Castro and Meinhardt collect and filter the water, Sam Wynsma uses another tool: his eyes. At each site, a team member always looks around the old-fashioned way.
“This is basically what you do when you’re 12: go look by ponds and streams and flip logs, looking for frogs, toads and newts,” Wynsma said.
Castro believes he saw salamander eggs on a previous site visit. Thanks to DNA tests, he will soon know for sure.
“That’s the power of this environmental DNA,” he said. “They are elusive, microscopic creatures and pathogens, even more so. With environmental DNA, it really allows us to see what we can’t actually see.
The Petersburg Ranger District will have to wait one to three months for test results. But they’re already thinking about ways the public can help stop the spread of the fungus. One idea is to set up shoe washing stations at sites where chytrid is detected. Castro, Meinhardt, and Wynsma clean their boots with a solution of bleach and water after visiting each site to avoid contaminating other parts of the forest.
Castro hopes the project will draw more attention to amphibians that often go unnoticed.
“They are out of sight, out of mind,” he said. “You often consider fishery resources first. And while they aren’t the charismatic species we see climbing trees and howling at the moon, they are part of the natural environment.
A part of the environment that is hopefully here to stay.