Most S'pore corals hit by bleaching event have recovered

Mortality rate in 2024 incident less severe than in previous mass bleaching events

- Zachary Lim

Singapore's corals, which had been gripped by a mass bleaching event between May and October 2024, have mostly recovered, with an estimated 5 per cent of corals left dead after the incident.

This mortality rate is less severe compared with earlier bleaching events. In the aftermath of the 2016 bleaching event, for example, coral mortality rate was 10 per cent, according to a 2016 scientific report.

The Straits Times had earlier reported that mortality was about 20 per cent in 1998, and 12 per cent in 2010.

Coral scientist Jani Tanzil, the facility director at St John's Island National Marine Laboratory (SJINML), told ST: "Based on observations during reef surveys, corals tagged and also corals outplanted as part of a reef restoration research project at Kusu Island, most of the corals that had bleached have recovered fully, with mortality rates low."

Corals get their vibrant colours from microscopic algae called zooxanthellae that live in their tissues. When they get stressed from rising sea surface temperatures, the corals expel the algae and turn ashen white in a phenomenon known as coral bleaching.

These algae supply the corals with nutrients to live, so when bleaching occurs, the coral becomes vulnerable to diseases and may eventually succumb to death.