Swirls of green are visible in the waters of the central and northern Adriatic Sea in this Copernicus Sentinel-3 satellite image from 2 May 2025. The vibrant coloration reveals the presence of an algal bloom that developed earlier in the month, likely triggered by unusually warm sea temperatures combined with recent heavy rainfall. The rainfall increased nutrient-rich river runoff into the sea, creating ideal conditions for algae to flourish.
The Copernicus Sentinel-3 image captures the extent of the bloom, with vivid green areas standing out against the deeper blues of unaffected waters. Such blooms are often seasonal, but their intensity and frequency can increase under certain environmental pressures, including climate change and pollution.
Algal blooms can have significant ecological and economic consequences. When large blooms die off, the decomposition process consumes oxygen in the water, which can lead to hypoxic conditions harmful to marine life. This disrupts local ecosystems and can impact fisheries and tourism industries. According to the Copernicus Marine Service, blooms like this one are monitored to inform environmental management strategies and help policymakers address eutrophication and related threats.
Featured image credit: European Union, Copernicus Sentinel-3 imagery
