Coral bleaching

Definition

Coral bleaching is the process where corals lose their vibrant colors and become white due to the expulsion of the symbiotic algae, known as zooxanthellae, that live in their tissues. This phenomenon occurs when corals are stressed by environmental factors like increased sea temperatures, pollution, or changes in water quality, which can lead to a decline in coral health and biodiversity.

5 Must Know Facts For Your Next Test

1. Coral bleaching can occur when sea temperatures rise just 1-2 degrees Celsius above normal for an extended period.
2. If conditions improve, some corals can recover and regain their zooxanthellae, but prolonged bleaching can lead to coral mortality.
3. Bleached corals are more susceptible to disease and can experience reduced reproductive success and growth rates.
4. Global warming and climate change are significant factors driving the frequency and severity of coral bleaching events worldwide.
5. Coral reefs support about 25% of all marine species despite covering only 1% of the ocean floor, making their health crucial for marine biodiversity.

Review Questions

• How does coral bleaching affect the overall health of coral reefs and their associated marine life?
  • Coral bleaching negatively impacts the health of coral reefs by reducing the energy supply that corals receive from zooxanthellae, leading to weakened coral structures. This decline affects the entire reef ecosystem since many marine species rely on coral reefs for habitat, food, and protection. As corals become more susceptible to disease and mortality, the loss of biodiversity can lead to further imbalances in the marine environment.
• Discuss the connection between ocean warming and coral bleaching, highlighting specific environmental stressors that contribute to this phenomenon.
  • Ocean warming is a key driver of coral bleaching because even slight increases in water temperature can stress corals, causing them to expel their zooxanthellae. Other environmental stressors such as pollution, sedimentation, and changes in salinity also contribute to this process by compromising coral health. These stressors often work in combination, exacerbating the effects of temperature rise and leading to more frequent and severe bleaching events across various regions.
• Evaluate the potential long-term consequences of widespread coral bleaching on marine ecosystems and human communities dependent on them.
  • Widespread coral bleaching can have severe long-term consequences for marine ecosystems, leading to decreased biodiversity as fish populations that rely on healthy reefs decline. The loss of coral reefs can disrupt fishing industries and tourism economies in coastal communities that depend on these ecosystems for livelihood. Additionally, degraded reefs may lead to increased coastal erosion and diminished protection against storm surges, further impacting human safety and economic stability in these areas.

Related terms

Zooxanthellae: Photosynthetic algae that live in symbiosis with corals, providing them with energy through photosynthesis and contributing to their color.

Ocean acidification: The decrease in pH levels of ocean water caused by increased absorption of carbon dioxide, which can negatively affect coral growth and health.

Ecosystem resilience: The ability of an ecosystem to recover from disturbances or stressors, such as coral bleaching, and maintain its functions and biodiversity.