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.
Back2Basics: Coral Reefs and Coral Bleaching
- 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.
Understanding Coral Bleaching
- 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.
Climate Change’s Impact on Coral Reefs
- 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.
Significance of Coral Reefs
- 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.
