Coral bleaching

Definition

Coral bleaching is a phenomenon where corals lose their vibrant colors and turn white, primarily due to stress factors like increased water temperature, pollution, or changes in salinity. This process occurs when corals expel the symbiotic algae (zooxanthellae) that live in their tissues and provide them with essential nutrients and color. As a significant threat to biodiversity, coral bleaching can lead to the degradation of coral reefs, which serve as critical habitats for numerous marine species.

5 Must Know Facts For Your Next Test

1. Coral reefs are among the most diverse ecosystems on Earth, supporting around 25% of all marine species despite covering less than 1% of the ocean floor.
2. Increased sea temperatures by just 1-2°C above normal can trigger coral bleaching events, making climate change a primary driver of this phenomenon.
3. Coral bleaching is often exacerbated by human activities such as coastal development, pollution, and overfishing, further stressing coral ecosystems.
4. When corals experience bleaching, they may recover if conditions improve, but repeated bleaching events can lead to long-term damage or death.
5. Healthy coral reefs provide essential ecosystem services like coastal protection, tourism opportunities, and sources of food for millions of people worldwide.

Review Questions

• What are the main environmental stressors that lead to coral bleaching, and how do they affect coral health?
  • The primary environmental stressors leading to coral bleaching include increased water temperature, pollution, and changes in salinity. When water temperatures rise even slightly above normal levels, corals expel their symbiotic zooxanthellae algae, leading to a loss of color and essential nutrients. Pollution can introduce harmful substances into the marine environment, further stressing corals and disrupting their ability to thrive. These factors together create conditions that significantly compromise coral health and resilience.
• Discuss the potential ecological consequences of widespread coral bleaching on marine biodiversity.
  • Widespread coral bleaching can have severe ecological consequences for marine biodiversity. Coral reefs provide habitat for countless marine species; when reefs degrade due to bleaching, the complex ecosystems they support can collapse. This loss of habitat can lead to declines in fish populations and other marine organisms that rely on healthy reefs for shelter, feeding, and breeding. The decline in biodiversity can create a cascading effect throughout the entire marine food web and disrupt important ecosystem services.
• Evaluate the long-term implications of climate change on coral reef ecosystems and global biodiversity as a whole.
  • The long-term implications of climate change on coral reef ecosystems are dire and extend to global biodiversity. As sea temperatures continue to rise due to climate change, the frequency and severity of coral bleaching events will likely increase. This could result in widespread reef degradation and loss of habitat for many marine species, leading to decreased biodiversity. Furthermore, as coral reefs play a crucial role in coastal protection and supporting fisheries, their decline could have economic impacts on communities reliant on these resources. Overall, the health of coral reefs is intricately linked to the broader health of marine ecosystems and global biodiversity.

Related terms

zooxanthellae: Microscopic algae that live in the tissues of corals and provide them with energy through photosynthesis.

ocean acidification: The reduction in pH levels of ocean water due to increased carbon dioxide absorption, which negatively affects coral growth and health.

marine biodiversity: The variety of life forms in ocean ecosystems, including the different species of plants, animals, and microorganisms, all of which can be impacted by coral bleaching.