Coral bleaching

Definition

Coral bleaching is a phenomenon where coral polyps expel the symbiotic algae, known as zooxanthellae, that live within their tissues, causing them to lose their vibrant colors and turn white. This process often occurs due to stress factors such as increased sea temperatures, pollution, and ocean acidification, which ultimately threaten coral reef ecosystems and biodiversity.

5 Must Know Facts For Your Next Test

1. Coral bleaching can occur when water temperatures rise just 1-2 degrees Celsius above normal levels for an extended period.
2. Bleached corals are more susceptible to disease and have a lower chance of survival if normal conditions do not return.
3. Around 50% of the world's coral reefs have experienced significant bleaching events over the past few decades due to climate change.
4. Coral reefs support approximately 25% of all marine species, making their health vital for overall ocean biodiversity.
5. Efforts to reduce greenhouse gas emissions and protect marine environments are crucial to mitigate the impacts of coral bleaching.

Review Questions

• How does increased sea temperature contribute to the process of coral bleaching?
  • Increased sea temperatures lead to coral bleaching by causing stress to coral polyps, prompting them to expel their symbiotic zooxanthellae. These algae are critical for the corals' nutrition and vibrant coloration; without them, corals lose their color and become white. Prolonged exposure to high temperatures can ultimately result in coral death if conditions do not normalize.
• Evaluate the long-term ecological implications of coral bleaching on marine ecosystems.
  • Coral bleaching has severe long-term implications for marine ecosystems. As corals die off due to repeated bleaching events, the entire ecosystem suffers because many marine species depend on healthy reefs for habitat and food. The decline in biodiversity can disrupt food webs and lead to the collapse of local fisheries, impacting human communities that rely on these resources for livelihood.
• Propose potential strategies to mitigate coral bleaching in the context of climate change and environmental policy.
  • To mitigate coral bleaching in the face of climate change, strategies could include implementing stronger regulations on carbon emissions to limit global warming. Establishing marine protected areas can help shield vulnerable reefs from pollution and overfishing. Additionally, restoring damaged reefs through active restoration projects and promoting public awareness about sustainable practices are critical. These strategies must be supported by international cooperation, as oceanic changes do not respect national boundaries.

Related terms

zooxanthellae: Microscopic algae that live in symbiosis with coral polyps, providing them with essential nutrients through photosynthesis and contributing to the corals' coloration.

ocean acidification: The process by which the ocean becomes more acidic due to increased carbon dioxide (CO2) levels in the atmosphere, affecting marine life, particularly organisms with calcium carbonate structures, like corals.

marine ecosystems: Complex communities of organisms that live in ocean environments, including coral reefs, which support diverse marine life and provide crucial ecosystem services.