A scientist is investigating the impact of an invasive insect and the chemicals used to combat it on the wildlife in ancient 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, various entities including Parks Canada, the province, local groups, and private landowners have been employing insecticides such as imidacloprid and dinotefuran.
However, Mathilde Christjansen, a graduate 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. She highlighted that imidacloprid, designed to impact insect nervous systems, has been detected in the brains of other creatures like fish and tadpoles.
Rather than studying all species across all hemlock forests individually, Christjansen and her team are focusing on using the eastern red-backed salamander as a bioindicator species to provide insights into the overall ecosystem health. This sensitive amphibian can indicate environmental changes and pollution levels.
For their research, scientists deployed coverboards in forests last year to create salamander habitats. They monitored these boards regularly to count the salamanders underneath, conducting measurements and tagging operations. Some forests under study are treated with either or both insecticides, while others remain untreated.
Behavioral tests were also conducted on the salamanders found, including light prodding to observe their response to predation and turning them upside down to assess their recovery speed. Christjansen emphasized that the salamanders’ well-being, population size, and health status could provide clues about potential ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, explained that salamanders are vital forest health indicators due to their abundance and biomass, surpassing that of deer in Eastern Canadian woodlands.
The study also examines how declining hemlock trees affect salamanders. Chris Edge, a supervisor and scientist with the Canadian Forest Service, highlighted that dying hemlocks disrupt the unique forest microclimates that provide ideal salamander habitats, potentially leading to population and behavioral changes due to decreased moisture levels.
The project involves collaboration between Mount Allison University, the Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan. It forms part of a broader initiative aimed at assessing forest health in Eastern Canada.
Christjansen anticipates continuing her study until the following year after collecting data throughout the summer. She plans to analyze the collected information and field videos to draw conclusions about the research findings.