Red Sea coral reefs under threat

Problems

• The Red Sea coral reef is one of the world's most diverse and resilient ecosystems. It stretches about 4,000 km along Egypt, Sudan, Eritrea, Saudi Arabia, Yemen, Israel, Jordan, and Djibouti coasts. It hosts more than 1,200 species of fish, 250 species of coral, and many other marine organisms. It also provides significant benefits for human well-being, such as food security, tourism revenue, coastal protection, and cultural heritage.
  

• Major threats to the Red Sea coral reef

  The Red Sea coral reef is facing multiple threats from human activities and environmental factors. Some of the threats include mass tourism, overfishing, pollution, sedimentation, oil spills, coastal development, ocean acidification, seawater warming, tropical storms, disease outbreaks, vessel damage, marine debris, and invasive species. These threats can damage or destroy the coral reef and its biodiversity.
  
  Overfishing is one of the most serious threats, which reduces the abundance and diversity of fish and other reef animals. Overfishing also disrupts the ecological balance and function of the reef, making it more vulnerable to other stressors. For example, overfishing can reduce the number of herbivorous fish that graze on algae and keep them from overgrowing on the coral surface. This can lead to a phase shift from a coral-dominated to an algae-dominated reef.
  
  Another major threat is climate change, which affects the physical and chemical conditions of the ocean. Climate change can cause seawater temperatures to rise above the optimal coral growth and survival range. This can trigger coral bleaching, which occurs when corals expel the symbiotic algae that provide them with food and color. Bleached corals are weakened and more susceptible to diseases and mortality5. Climate change can also increase seawater acidity due to higher carbon dioxide levels.
  
  While mass bleaching and death occur when corals are exposed to temperatures that are 1-2° Celsius (1.8-3.6° Fahrenheit) above their average summer maximum, scientists found that the reefs in the Gulf of Aqaba, at the northern tip of the Red Sea, can survive a rise of 5-6°C (9-10.8°F).
  
  This resilience is a product of how the corals migrated from warmer waters. During the last ice age, some 20,000 years ago, sea levels fell, and the Red Sea was cut off from the Indian Ocean. When the ice caps melted, the region was flooded again, the Red Sea reconnected, and new life forms made their way up to the northern part of the Red Sea, where water temperatures dropped significantly. Only the species adapted to the south’s warm waters could send their larvae north to populate the Gulf of Aqaba.
  
  Researchers found the corals in the north of the Red Sea are still adapted to waters much warmer than their average temperatures. In contrast to most corals elsewhere that live close to their thermal maximum, coral reefs in the Gulf of Aqaba have a much wider gap between the bleaching threshold and maximum temperature.