A study is being conducted by a researcher to investigate the impact of an invasive insect and the chemicals used to combat it on various species residing in aged hemlock forests.
The hemlock woolly adelgid (HWA) has been causing significant damage to forests in southwestern Nova Scotia for nearly ten years. To control its spread, insecticides like imidacloprid and dinotefuran have been employed by Parks Canada, the province, local groups, and private landowners.
Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the limited knowledge regarding the effects of woolly adelgid and the insecticides on other species. She expressed concerns about the potential impact of imidacloprid on the nervous systems of various animals, citing its presence in the brains of fish and tadpoles.
Instead of individually studying all species in every hemlock forest, Christjansen’s team is focusing on using the eastern red-backed salamander as a bioindicator species to provide insights into the overall ecosystem health.
The researchers placed coverboards in the forests last year to observe salamanders, periodically monitoring and tagging them. Some forests are treated with imidacloprid, dinotefuran, or both, while others remain untreated.
Behavioral tests were conducted on the salamanders, such as gentle prodding to assess their response to predation and flipping them over to observe their agility. Christjansen emphasized that the salamanders’ well-being and characteristics can indicate broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, noted the significance of salamanders as forest health indicators due to their abundance and biomass compared to other species like deer.
The research also examines how dying hemlocks affect salamanders, as these trees provide essential habitat features. Chris Edge, a scientist with the Canadian Forest Service, emphasized the importance of hemlocks in maintaining cool and moist microclimates in forests.
Salamanders, with their moisture-dependent skin, are sensitive to changes in forest conditions caused by declining hemlocks. The study involves collaboration between various institutions and forms part of a broader investigation into forest health in Eastern Canada.
Christjansen plans to continue her research until the following year, analyzing data collected during the summer to gain further insights into the impacts of HWA and insecticides on salamanders and forest ecosystems.
