On 26 April 2022, a report published by Scotland’s Centre of Expertise for Waters (CREW) found that 97% of the 142 monitored Scottish lochs and reservoirs recorded an increase in temperature between 2015 and 2019. While most warmed by up to 1.0°C per year over this period, 9% recorded a greater increase, with rises of up to 1.3°C per year noted.
Researchers warn that these changes increase the risk of harmful algal blooms developing, which could impact on the use of lochs and reservoirs for recreation, water supply, and as a safe habitat for wildlife.
The report suggests that waters in the south and east of Scotland are expected to warm the most at first, but the climate-related impact will reach all parts of the country by 2040.
The report makes a number of recommendations to address these impacts in the immediate term, such as reducing the amount of phosphorus and nitrogen, the main driver of algal blooms, entering lochs and reservoirs from their catchments. Sources of these plant nutrients, which are present in synthetic fertilisers as well as human and animal waste, include farm runoff and wastewater discharges. Actions, such as the creation of buffer strips and constructed wetlands aimed at reducing nutrient inputs, have started in many catchments across Scotland. Further recommendations, as well as further research to improve understanding of climate impacts on the complex functioning of lochs and reservoirs, are also included in the report.
Source: Scottish Government, 26 April 2022