What is a major contributing factor to coral bleaching?

Increased water temperature is a major contributing factor to coral bleaching. When water temperatures rise beyond the normal range for coral species, often due to climate change or localized events, corals become stressed. In response to this stress, corals expel the symbiotic algae (zooxanthellae) living within their tissues. These algae are crucial for the coral's nutrition through photosynthesis and provide the vibrant colors that corals are known for. Without them, the corals turn white, indicating bleaching. Prolonged exposure to elevated temperatures can lead to coral death and degradation of the coral reef ecosystem.

While decreased salinity levels, excessive nutrient runoff, and overfishing of herbivores also impact coral health, they are not the primary factors associated with the immediate phenomenon of coral bleaching as directly and significantly as increased water temperature.