A bleaching event refers to a significant loss or reduction in the population size of coral reefs due to stress from environmental factors such as rising ocean temperatures, pollution and other human activities. During these events, corals lose their symbiotic algae (zooxanthellae) which provide them with essential nutrients through photosynthesis. Without this relationship, the corals become weakened and may eventually die if conditions do not improve. Bleaching events have been increasing in frequency and severity due to climate change, making it a major threat to the survival of coral reefs worldwide.