A researcher is investigating the impact of an invasive insect and the chemicals used to combat it on the wildlife in ancient hemlock forests.
Hemlock woolly adelgid (HWA) has been causing extensive damage to forests in southwestern Nova Scotia for nearly ten years. To control its spread, various entities including Parks Canada, the province, local groups, and private landowners have been employing insecticides such as imidacloprid and dinotefuran.
Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the lack of knowledge regarding how woolly adelgid and the insecticides are affecting other species. She mentioned that imidacloprid, designed to impact insect nervous systems, has also been detected in the brains of animals like fish and tadpoles.
Instead of studying all species across all hemlock forests individually, Christjansen’s team is focusing on a single amphibian species to gain insights into the ecosystem. The eastern red-backed salamander is considered a reliable bioindicator due to its sensitivity to environmental changes and pollutants.
Last year, scientists placed coverboards in forests to serve as habitats for salamanders, which were then monitored periodically to count and measure the salamanders living beneath. Some forests under investigation are treated with either or both insecticides, while others remain untreated.
Behavioral tests were conducted on the salamanders, including gentle prodding to observe their responses to predation and flipping them upside down to assess their recovery speed. Christjansen emphasized that the salamanders’ condition and behavior could provide clues about broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, noted that salamanders are not only responsive to environmental changes but also serve as a significant indicator of forest health due to their population density.
The study also examines how dying hemlock trees affect salamanders. Chris Edge, a supervisor and scientist with the Canadian Forest Service, explained that the loss of hemlocks disrupts the unique habitat conditions they create, such as cool and moist microclimates essential for the salamanders.
Given the salamanders’ sensitive skin and moisture requirements, any reduction in forest moisture resulting from decreased foliage coverage due to dying hemlocks could impact salamander populations and behaviors.
The project involves collaboration among Mount Allison University, Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, as part of a broader investigation into forest health in Eastern Canada.
Christjansen plans to continue her study until the following year, analyzing the data and videos collected during the summer months.