A satellite orbiting high above Earth is providing scientists with valuable information on the health of a Nova Scotia river that provides important habitat for endangered species and is beloved by kayakers, fishermen and birdwatchers.
Imagery from the European Space Agency’s Sentinel-2 satellite underpins a new Canadian study that shows where conservation efforts on the St. Marys River and its lush waterfront have proven effective.
This is the first time that scientists from the Department of Fisheries and Oceans have used a satellite that can provide images with enough detail to determine whether environmental changes are natural or human-induced.
“We used higher-quality imagery that would better capture small-scale changes than other satellites used nationally,” said Caelin Murray, aquatic biologist at DFO and lead researcher on the study.
Most of the catchment area remains intact
The study found that the St. Marys River Basin is “relatively intact,” with 75 percent unaffected by human activity or natural disasters. Of the remaining 25 percent of land, which has been disturbed primarily by historical logging and agricultural practices, very little is regenerating.
Scientists focused particularly on a strip of land along the riverbank, known as the riparian zone, because of its importance to terrestrial and aquatic species, said Aimee Gromack, a senior biologist at DFO and a member of the research team.
The team paid attention to chemical runoff and vegetation loss, as well as other factors that could negatively impact the environment.
The study showed that 19 percent of the riverside zone has been disturbed and nine percent of this habitat showing signs of regeneration.
Gromack said the vegetation in this zone provides shade, filters chemicals from the water and serves as shelter for other species, so any disturbance could impact the entire ecosystem.
Nearby trees, which provide shade and cool the river water, play a vital role in the survival of endangered Atlantic salmon, which are very sensitive to higher temperatures.
Clearer satellite images
Murray said the team chose the St. Marys River for the study because compared to other watersheds, it has “very low environmental impacts,” which allows scientists to better understand what conservation methods have worked in the area, including initiatives by local organizations and land foundations.
The Sentinel-2 mission was the best option for this work because it offers images that are twice as sharp as NASA’s Landsat 9 satellite. In addition, the European satellite provides more up-to-date data because it visits the same location every five days, much shorter than Landsat 9’s 16-day interval, Murray said.
Jaimee Morozoff, director of conservation at the Nova Scotia Land Trust, said the DFO study will help the organization evaluate its conservation strategies. The trust already protects about 902 hectares of land on the St. Marys River.
“Was [a] science-based organization. We want to make the best decisions for biodiversity, using the latest information,” Morozoff said. “It’s a great tool to help inform some of our decisions.”
Morozoff said she hopes the study will help encourage similar studies to be conducted in areas that are not as well preserved as the St. Marys River.
Gromack agreed, saying this type of research could provide a baseline for conservation efforts beyond the St. Marys River in the years to come.
“This type of analysis could be done in other watersheds to better identify where conservation opportunities exist, look at those areas in more detail and consider available options,” Gromack said.
