What is the most likely cause of the coral bleaching shown below?

• A. Overfishing of herbivorous fish
• B. Increased sea surface temperatures due to climate change
• C. Decreased salinity from excessive rainfall
• D. Increased sedimentation from coastal erosion

Answer: (B)

Verified step by step guidance

1. Understand the concept of coral bleaching: Coral bleaching occurs when corals expel the symbiotic algae (zooxanthellae) living in their tissues due to stress, causing them to lose their color and become white. This stress is often linked to environmental changes.
2. Analyze the options provided: Each option represents a potential environmental stressor that could lead to coral bleaching. Evaluate how each factor impacts coral health and the likelihood of it being the primary cause.
3. Option 1: Overfishing of herbivorous fish - Herbivorous fish help control algae growth on coral reefs. Overfishing can lead to algae overgrowth, but this is not directly linked to coral bleaching, which is primarily caused by stress affecting the coral-algae symbiosis.
4. Option 2: Increased sea surface temperatures due to climate change - Elevated temperatures disrupt the coral-algae relationship, causing the algae to be expelled. This is the most common and well-documented cause of coral bleaching globally.
5. Option 3: Decreased salinity from excessive rainfall and Option 4: Increased sedimentation from coastal erosion - Both can stress corals, but they are less likely to be the primary cause compared to temperature changes. Increased sedimentation can block sunlight, and decreased salinity can affect coral physiology, but neither is as impactful as temperature changes in causing widespread bleaching.