Coral bleaching

Definition

Coral bleaching occurs when corals lose their vibrant colors and become pale or white, typically due to stress factors like increased water temperatures, pollution, or changes in sunlight. This phenomenon affects the symbiotic relationship between corals and the algae (zooxanthellae) that live within them, providing essential nutrients and color to the coral. When stressed, corals expel these algae, leading to bleaching and making them more vulnerable to disease and mortality.

5 Must Know Facts For Your Next Test

1. Coral bleaching is often triggered by prolonged exposure to temperatures just 1-2 degrees Celsius above normal levels, typically during heatwaves.
2. Bleached corals can recover if the stressor is removed in time; however, prolonged bleaching can lead to coral death and loss of biodiversity.
3. Coral reefs support about 25% of all marine species despite covering less than 1% of the ocean floor, making them vital to marine ecosystems.
4. Pollution from agricultural runoff and plastic waste can exacerbate coral bleaching by introducing harmful substances into coastal waters.
5. The frequency and intensity of coral bleaching events are increasing due to climate change, leading to heightened concern for the future of coral reefs globally.

Review Questions

• What are the main causes of coral bleaching and how do they impact coral health?
  • Coral bleaching is primarily caused by factors like increased water temperatures, pollution, and changes in sunlight. Elevated temperatures lead corals to expel their symbiotic zooxanthellae algae, which are essential for their color and nutrient supply. Without these algae, corals become more susceptible to diseases and starvation, severely impacting their health and survival.
• Discuss the potential ecological consequences of widespread coral bleaching on marine ecosystems.
  • Widespread coral bleaching can lead to significant ecological consequences for marine ecosystems. Coral reefs are home to a diverse array of marine life; their degradation results in habitat loss for many species. As coral health declines, fish populations may also suffer due to reduced shelter and food sources. This cascading effect can disrupt entire food webs and diminish biodiversity in ocean environments.
• Evaluate the effectiveness of conservation strategies aimed at mitigating coral bleaching effects in the context of climate change.
  • Conservation strategies aimed at mitigating coral bleaching effects include establishing marine protected areas, restoring damaged reefs, and reducing local stressors such as pollution. While these measures can help improve resilience against bleaching events, their effectiveness is limited if global climate change continues unchecked. A comprehensive approach that includes reducing greenhouse gas emissions is crucial for long-term coral health; otherwise, even well-managed reefs may still be vulnerable to increasing ocean temperatures and acidification.

Related terms

zooxanthellae: Tiny algae that live inside coral tissues and provide energy through photosynthesis, playing a crucial role in the health and color of corals.

ocean acidification: The process by which the ocean becomes more acidic due to increased carbon dioxide absorption, negatively affecting marine organisms like corals.

marine ecosystem: A community of living organisms, including plants, animals, and microorganisms, that interact with each other and their environment in ocean habitats.