A researcher is investigating the impact of an invasive bug and the chemicals used to eradicate it on the species residing in ancient hemlock forests in southwestern Nova Scotia.
For close to ten years, hemlock woolly adelgid (HWA) has been causing significant damage to forests in the region. Various entities, including Parks Canada, the province, local organizations, and private landowners, have been combatting the spread of HWA using insecticides such as imidacloprid and dinotefuran.
However, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the lack of knowledge regarding the effects of woolly adelgid and the insecticides on other species. She pointed out that while imidacloprid is designed to impact insect nervous systems, it has been detected in the brains of other animals like fish and tadpoles.
To streamline their study, Christjansen and her team are focusing on the eastern red-backed salamander as a bioindicator species to provide insights into the overall forest ecosystem. These salamanders are sensitive to environmental changes and pollutants, making them ideal indicators of forest health.
The researchers placed coverboards in the forests last year to serve as habitats for salamanders. They monitored the salamanders living beneath these coverboards, conducting surveys, measuring, and tagging them in the process. Some forests under study are treated with either or both insecticides to combat HWA, while others remain untreated.
In addition to population surveys, the team conducted behavioral tests on the salamanders, observing their responses to stimuli like light poking and being flipped upside down. These tests aim to gauge the salamanders’ well-being and compare their conditions across treated and untreated forests.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, emphasized the importance of salamanders as forest health indicators due to their abundance and ecological significance.
Chris Edge, a supervisor and scientist with the Canadian Forest Service, highlighted how dying hemlock trees impact salamanders by altering their habitat conditions. The loss of hemlocks disrupts the unique microclimates these trees create, affecting the moisture levels crucial for salamander survival.
The project, a collaborative effort involving several institutions including Mount Allison University, Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, forms part of a comprehensive study on forest health in Eastern Canada.
Christjansen plans to continue her research until next year, analyzing the data and videos collected during the summer fieldwork. The study aims to shed light on the intricate relationships between invasive species, insecticides, and forest ecosystems, particularly focusing on the well-being of salamander populations.