This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Every summer, Québec rivers increasingly reach water temperature levels that threaten Atlantic salmon (Salmo salar). Just a few extra degrees can make the difference between a favorable and hostile habitat for this iconic species.
Because of climate change, the issue is no longer simply predicting how much rivers will warm, but determining where to take action to protect them. One possible solution is the reforestation of riparian zones, the edges of streams and rivers. Trees lining waterways provide shade, which limits sun exposure and keeps temperatures cooler.
But how can we determine what areas will actually benefit from reforestation? Our study, conducted on the Dartmouth River in the Gaspé Peninsula—a major waterway in the region known for its Atlantic salmon population and recreational fishing—provides a new tool to answer this question. A river's water temperature depends on several factors, including air temperature, flow rate and groundwater inflow.
However, solar radiation remains one of the main sources of energy responsible for rivers warming during the summer. More sunlight reaches the water's surface in areas where riparian vegetation has been degraded by human activities. The consequences of this are particularly significant for Atlantic salmon, a species adapted to cold waters.
Atlantic salmon growth and performance are generally optimal at temperatures below 20°C (68 degrees Fahrenheit), and signs of physiological stress appear when the water temperature exceeds 20–23°C (68–73 degrees Fahrenheit). Beyond these critical thresholds, this stress can affect the growth, feeding and reproduction of the species. Protecting thermal refuges has therefore become a major conservation topic.
To better understand the effect of riparian vegetation on water warming in the Dartmouth River, our research team at the INRS' Eau Terre Environnement Research Center launched a new project to assess the role of riparian vegetation in providing shade and controlling solar exposure—two key factors that determine the quality of salmon habitat. We used a remote sensing technology called LiDAR (Light Detection and Ranging), which produces a highly detailed three-dimensional representation of the terrain and surrounding vegetation. The analysis was conducted at a resolution of just one meter (3.3 feet), allowing us to identify the most exposed sections of the watercourse with high precision.
Extract — continue reading at the source.
