A researcher is investigating the impact of an invasive bug and the chemicals used to combat it on the wildlife in ancient hemlock forests in southwestern Nova Scotia. Hemlock woolly adelgid (HWA) has been causing significant damage to the forests in the region for nearly ten years. To control its spread, various entities such as Parks Canada, the provincial government, local groups, and private landowners have been employing insecticides like imidacloprid and dinotefuran.
Nevertheless, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., pointed out the lack of knowledge regarding the effects of woolly adelgid and the insecticides on other species. Christjansen emphasized that while imidacloprid is designed to impact insect nervous systems, it can also affect the nervous systems of other creatures, as evidenced by its presence in the brains of animals like fish and tadpoles.
Instead of studying all species across various hemlock forests individually, Christjansen’s team is focusing on a single small amphibian as a representative of the ecosystem. The eastern red-backed salamander was chosen as it is a sensitive bioindicator species, responsive to both environmental conditions and pollutants. Monitoring involves placing coverboards in the forests to serve as salamander habitats, followed by periodic surveys to assess salamander populations, measure them, and tag them for identification.
Behavioral experiments were also conducted on the salamanders to observe their reactions to stimuli like light prodding and being turned upside down. According to Christjansen, the salamanders’ well-being and behaviors can offer insights into potential impacts on other parts of the ecosystem.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, highlighted the salamanders’ importance as indicators of forest health due to their abundance in Eastern Canadian woodlands, surpassing even deer in biomass.
The study is also examining how dying hemlock trees influence salamanders. Chris Edge, a scientist with the Canadian Forest Service and another supervisor of the project, explained that the demise of hemlocks disrupts the unique habitats they provide due to their dense canopies, leading to changes in moisture levels that could affect salamander populations.
The collaborative project involves 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 collected data and field videos from this summer.