This image comes courtesy of Copenicus Sentinel-2A over the Kingdom of Tonga . Isn't this a super picture? It shows the island of Tongatapu and some nearby smaller islands in the archipelago of 169 islands. [Image processing of Sentinel data by ESA]
There are coral reefs north of the main island. ESA reports that
scientists are experimenting with Sentinel-2 to monitor corals and detect coral bleaching. That happens when algae living in the corals’ tissues, which are essential to coral survival, are expelled owing to higher temperature. The whitening coral may die, with subsequent effects on the reef ecosystem, and thus fisheries, regional tourism and coastal protection.
The recent El Niño weather phenomenon has caused increased bleaching across the world’s corals, and scientists are finding Sentinel-2’s coverage helpful in monitoring this at reef-wide scales.