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Biologists on Alaska’s national forests work to learn more about deadly amphibian fungus

April 27, 2021

Employees taking eDNA samples on Tongass National Forest.
Forest Service employees take eDNA samples throughout the Tongass National Forest. USDA Forest Service photo by Nate Catterson.

Biologists on the Tongass National Forest plan to use the 2021 field season to learn as much information as they can on the amphibian chytrid fungus, or Batrachochytrium dendrobatidis (Bd). While some frog species (e.g., bullfrogs) appear resistant to the disease, Bd has caused the decline of more than 500 species of amphibians worldwide, including 90 possible extinctions.

A wood frog on the grass in Tongass National Forest.
The wood frog is just one of the species found on the Tongass National Forest. USDA Forest Service photo by Nate Catterson.

The hope is that spending this field season collecting samples will help refine the distribution of the fungus across the forests. This follows a study last year by the Tongass Wildlife and Fisheries program where eDNA was used to survey the presence of Bd in waterbodies at several locations across the forest. The pathogen was found at multiple sites on Prince of Wales Island, Wrangell Island and at one of 10 sites in the Yakutat area.

While describing its distribution is an important step in managing the disease, regional biologists recognize that this alone is insufficient to protect Alaska's native amphibians. To better manage this and other amphibian diseases, the Alaska Region is working with its forests and interagency partners to spearhead the development of an amphibian disease working group.

The group will focus on developing strategies and protocols to understand and address the factors facilitating the spread of amphibian pathogens, to limit further spread of the pathogens and to minimize the impact of these diseases on Alaska's frogs and salamanders.

A western toad on the ground, Tongass National Forest.
The Western toad is one of the species found on the Tongass National Forest. USDA Forest Service photo by Ben Limley.

While two frog species have been accidentally introduced to the Tongass, Alaska's two national forests also host native species: three salamander and three frog species native to the Tongass. Two of those frog species extend their range into the Chugach. These native amphibians are vital components of the forests, consuming a suite of invertebrates and being prey for many fish, birds and small carnivores.

The frog is also an important cultural symbol for some Alaska Native peoples, depicted in their art and stories.