Meaning of Coral Bleaching:
Coral bleaching refers to the paling of coral color or the decline in zooxanthellae, which are microscopic algae that live inside the coral tissues. The primary cause of coral bleaching is climate change, specifically the increase in ocean temperatures.

Causes of Coral Bleaching:
1. Climate Change: The main driver of coral bleaching is the rising temperature of the ocean. When water temperatures are too high, corals become stressed and expel the symbiotic algae living in their tissues. Without these algae, corals lose their vibrant colors and appear bleached.

2. Ocean Acidification: Another consequence of climate change is ocean acidification, which occurs when the ocean absorbs excess carbon dioxide from the atmosphere. Acidic waters make it difficult for corals to build their calcium carbonate skeletons, weakening their overall resilience and making them more susceptible to bleaching.

3. Pollution: Human activities such as pollution, including runoff from agricultural practices and coastal development, can contribute to coral bleaching. Excessive nutrient levels in the water can lead to increased algae growth, which can smother corals and prevent them from receiving sufficient light for photosynthesis.

4. Overfishing: Overfishing can disrupt the delicate balance of coral reef ecosystems. Removing predators such as fish can lead to an increase in the population of herbivorous species, which can overgraze on algae that compete with corals for space. Without this natural control, algae can outcompete corals and contribute to their decline.

Impacts of Coral Bleaching:
1. Biodiversity Loss: Coral reefs are among the most diverse ecosystems on the planet, supporting a vast array of marine species. When corals bleach and eventually die, it disrupts the entire reef ecosystem, leading to a loss of biodiversity and species extinction.

2. Economic Consequences: Coral reefs provide essential ecosystem services, such as fisheries, tourism, and coastal protection. Coral bleaching can devastate these industries, affecting the livelihoods of communities that rely on reef ecosystems for income and food security.

3. Breakdown of Ecosystem Functioning: Coral reefs play a crucial role in maintaining the health and functioning of the oceans. They act as nurseries for many fish species, provide habitats for numerous marine organisms, and protect coastlines from erosion. The loss of coral reefs due to bleaching can have far-reaching ecological consequences.

In conclusion, coral bleaching refers to the paling of coral color or decline in zooxanthellae due to climate change, primarily caused by rising ocean temperatures. It is a significant threat to coral reefs and the ecosystems and communities that depend on them. Efforts to mitigate climate change and reduce local stressors are crucial for the long-term survival and conservation of coral reefs.