Why can freshwater floods damage inshore coral reefs?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

coral reef The Great Barrier Reef, off the coast of Queensland, Australia, is the world's largest coral reef.

Freshwater floods can damage inshore coral reefs because corals are restricted to environments with normal oceanic salinity, typically ranging between 30 and 40 parts per thousand.1

When heavy rainfall or flooding introduces large volumes of fresh water into these coastal areas, it disrupts the necessary saline balance of the marine environment. This sudden drop in salinity can be lethal to the coral colonies, as demonstrated by historical events where prolonged cyclonic rains resulted in the widespread death of reef life to a depth of several metres below the mean tide level.1