What is a major consequence of coral bleaching?

Coral bleaching occurs when corals lose their vibrant colors, often due to stress factors such as rising sea temperatures, pollution, or changes in water quality. This loss of color happens when the symbiotic algae, known as zooxanthellae, that live within the coral tissues are expelled. These algae provide essential nutrients and energy to the coral through photosynthesis.

When bleaching occurs, it leads to a severe decline in coral health. Without the algae, the coral struggles to survive, and this often leads to the death of the coral. Healthy coral reefs provide critical habitats and food sources for a diverse array of marine life, including fish. Therefore, when the coral dies, it ultimately results in a lack of food and habitat for these fish populations, which can lead to declines in their numbers or even local extinction.

This situation contrasts starkly with the other options, which suggest positive changes such as increased fish populations, expansion of coral species, or improved water quality—outcomes that are unlikely in the face of widespread coral die-offs.