A scientist is conducting research to explore 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 mitigate its spread, insecticides such as imidacloprid and dinotefuran have been employed by Parks Canada, the province, local groups, and private landowners.
However, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the lack of understanding regarding the effects of woolly adelgid and insecticides on other species. She emphasized that while imidacloprid is designed to impact insect nervous systems, it has been detected in the brains of non-target animals like fish and tadpoles.
Rather than individually studying all species across hemlock forests, Christjansen’s team is utilizing the eastern red-backed salamander as a bioindicator to gauge the overall ecosystem health. This species is sensitive to environmental changes and pollutants, making it a valuable indicator for assessing forest well-being.
In the study, researchers placed coverboards in forests last year to serve as salamander habitats. They conducted periodic surveys to count and measure the salamanders underneath, tagging them for identification. Some forests under investigation are treated with either or both insecticides for HWA, while others remain untreated.
Behavioral tests were also conducted on the salamanders, including gentle prodding to observe their reaction to predation and flipping them over to assess their agility. Christjansen noted that the salamander’s population size, health status, and comparative size across different forest types could provide insights into broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a supervisor of the study, emphasized the salamander’s significance as a forest health indicator due to its responsiveness to environmental changes and substantial presence in forest ecosystems.
The research also examines the repercussions of dying hemlock trees on the salamander population. Chris Edge, another project supervisor and scientist with the Canadian Forest Service, highlighted that the demise of hemlocks disrupts the unique forest habitats they create, impacting salamanders reliant on moist environments.
Salamanders possess highly sensitive skin that necessitates ample moisture. The reduction in forest foliage due to dying hemlocks can lead to drier conditions, potentially affecting salamander populations and behaviors.
The study is a collaborative effort involving Mount Allison University, the Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, focusing on forest health in Eastern Canada. Christjansen plans to continue her research until next year, analyzing the data and videos gathered during the summer fieldwork.
Photo captions: Mathilde Christjansen, a master’s student at Mount Allison University, leads the research project. Chris Edge, Julia Riley, Emily Doherty, and Mathilde Christjansen are part of the research team studying the impacts of HWA and insecticides.
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