Oceans And Seas Questions Long
Coral bleaching is a phenomenon that occurs when coral reefs lose their vibrant colors and turn pale or white. It is primarily caused by a combination of environmental stressors, with the major factors contributing to coral bleaching being:
1. Elevated water temperatures: One of the primary causes of coral bleaching is the increase in water temperatures. When the water gets too warm, corals expel the symbiotic algae called zooxanthellae, which provide them with essential nutrients through photosynthesis. Without these algae, corals lose their main source of food and energy, leading to bleaching.
2. Ocean acidification: Another significant factor contributing to coral bleaching is ocean acidification. As carbon dioxide (CO2) levels increase in the atmosphere, a portion of it is absorbed by the oceans, leading to a decrease in pH levels. Acidic waters make it difficult for corals to build their calcium carbonate skeletons, weakening their structure and making them more susceptible to bleaching.
3. Pollution and nutrient runoff: Excessive pollution and nutrient runoff from human activities, such as agriculture and coastal development, can also contribute to coral bleaching. These pollutants can lead to an overgrowth of algae, which competes with corals for space and resources. Additionally, nutrient-rich waters can promote the growth of harmful bacteria and viruses that can further stress corals and contribute to bleaching.
4. UV radiation: Ultraviolet (UV) radiation from the sun can also play a role in coral bleaching. When corals are exposed to high levels of UV radiation, it can cause damage to their tissues and increase their susceptibility to bleaching. This factor is often exacerbated by other stressors, such as elevated water temperatures.
5. Coral disease and predation: Coral bleaching can also be influenced by the presence of diseases and predation. When corals are already stressed due to environmental factors, they become more vulnerable to diseases caused by bacteria, fungi, or viruses. Additionally, certain organisms like crown-of-thorns starfish can prey on corals, further weakening them and increasing the likelihood of bleaching.
It is important to note that these factors often interact and compound each other, making coral bleaching a complex issue. Climate change, in particular, plays a significant role in exacerbating these stressors, as rising temperatures and ocean acidification are largely driven by human-induced greenhouse gas emissions. Efforts to mitigate these factors and protect coral reefs are crucial for their long-term survival and the preservation of marine biodiversity.