Coral bleaching

Definition

Coral bleaching is a phenomenon where corals lose their vibrant colors and turn white due to stress factors, primarily elevated sea temperatures, which cause them to expel the symbiotic algae living in their tissues. This loss of algae not only affects the corals’ appearance but also their ability to obtain nutrients and energy, leading to weakened ecosystems. The occurrence of coral bleaching has significant implications for marine biodiversity and the health of ocean ecosystems as it is closely linked to climate change.

5 Must Know Facts For Your Next Test

1. Coral bleaching can occur when sea surface temperatures rise just 1-2 degrees Celsius above normal levels for extended periods.
2. Corals are more susceptible to bleaching during events like El Niño, which leads to significant temperature increases in ocean waters.
3. Once bleached, corals can recover if conditions improve; however, repeated bleaching events can lead to permanent damage and coral death.
4. Coral reefs support approximately 25% of all marine species, making their health crucial for overall marine biodiversity.
5. Restoration efforts for damaged coral reefs often include techniques like coral gardening or breeding heat-resistant coral species to combat the effects of climate change.

Review Questions

• What factors contribute to coral bleaching, and how do they impact the surrounding marine ecosystem?
  • Coral bleaching is mainly driven by stressors like elevated sea temperatures and pollution, which cause corals to expel their symbiotic algae. This impacts the marine ecosystem significantly because these algae provide essential nutrients and energy for corals. Without them, corals become weak and vulnerable, disrupting the entire food web that relies on healthy coral reefs as a habitat and feeding ground.
• Discuss the potential long-term consequences of coral bleaching on marine biodiversity and ocean health.
  • Long-term consequences of coral bleaching include reduced marine biodiversity, as many species rely on coral reefs for shelter and food. As corals die off, fish populations decline, affecting fisheries and human communities that depend on these resources. Furthermore, with less healthy reef structures, coastal protection from storms diminishes, increasing vulnerability for shorelines. Overall, the loss of coral reefs can lead to a cascade of ecological changes that compromise ocean health.
• Evaluate the effectiveness of current conservation strategies aimed at combating coral bleaching in the context of climate change.
  • Current conservation strategies include establishing marine protected areas (MPAs), promoting sustainable fishing practices, and enhancing coral resilience through selective breeding programs. While these approaches can provide some immediate benefits by reducing local stressors on reefs, their effectiveness is limited by the overarching threat of climate change. Without global efforts to mitigate greenhouse gas emissions and reduce sea temperature rise, even the best local strategies may struggle to keep pace with the rapid changes threatening coral ecosystems.

Related terms

Symbiotic Relationship: A close and often long-term interaction between two different biological species, such as corals and zooxanthellae algae, where both parties benefit.

Ocean Acidification: The decrease in pH levels of the ocean caused by increased carbon dioxide absorption, which can further stress coral reefs and impact their growth and survival.

Marine Biodiversity: The variety of life forms in ocean ecosystems, including the diversity of species within coral reefs that are affected by coral bleaching.