Central Idea

A notable example of colony resilience during a bleaching event is found near Japan’s Iriomote Island, where a colony bleached in 2016 exhibited signs of recovery by 2020.

About Iriomote Island

Iriomote Island is a picturesque island located in the Yaeyama Islands, part of Okinawa Prefecture in Japan.
It is the largest and southernmost inhabited island in the Yaeyama archipelago.
With its lush jungles, mangrove forests, and diverse wildlife, Iriomote Island is often referred to as the “Galapagos of the East.”
It is home to the Iriomote Yamaneko, or Iriomote cat, which is a critically endangered species of wildcat found only on this island.
The dense mangrove forests along the island’s rivers and estuaries serve as an important habitat for numerous species of birds, fish, and other wildlife.
To preserve the island’s unique ecosystem and cultural heritage, Iriomote Island is part of the Iriomote-Ishigaki National Park.

Corals are marine invertebrates that form colonies of polyps, which multiply and create reef structures.
Hard corals extract calcium carbonate to build hard exoskeletons, while soft corals add their skeletons to create coral reefs.
Corals have a mutually beneficial relationship with single-celled algae called zooxanthellae.
The zooxanthellae provide food and nutrients through photosynthesis, while corals provide a home and essential nutrients.
The zooxanthellae give corals their vibrant colors.

Causes of Bleaching: Environmental stressors like temperature changes, pollution, and high ocean acidity lead to coral bleaching.
Bleaching Process: Stressed corals expel the zooxanthellae, revealing their pale exoskeletons and disrupting the symbiotic relationship.
Impacts of Bleaching: Severe and prolonged bleaching events can result in coral death and the loss of biodiversity.

Warming Seas: Rising carbon emissions and greenhouse gases have caused increased global warming, resulting in warmer ocean temperatures.
Mass Bleaching: The frequency and intensity of mass bleaching events have risen in recent decades due to climate change.
Projections: Even with greenhouse gas reduction efforts, temperatures are expected to rise by 1.5°C to 2°C by the end of the century.

Biodiversity Hotspots: Coral reefs support over 25% of marine biodiversity despite covering only 1% of the seafloor.
Economic Value: Reefs contribute $2.7 trillion annually through trade, tourism, and employment opportunities.
Environmental Protection: Coral reefs provide habitat and serve as a natural defense against storm waves.
Regeneration Potential: Dead reefs can recover if sufficient fish species graze on the weeds that settle on dead corals, although the process takes several years.