-
Coral Bleaching
What causes coral bleaching?
-
1 Reply
-
Coral bleaching is primarily caused by environmental stressors, particularly increased water temperatures. When corals are exposed to prolonged periods of unusually high water temperatures, they become stressed and expel the symbiotic algae called zooxanthellae that live within their tissues. These algae provide corals with nutrients through photosynthesis and give them their vibrant colors.
When corals expel the zooxanthellae, the corals appear white or “bleached” because the underlying white calcium carbonate skeleton becomes visible. While corals can recover from mild bleaching events, severe or prolonged bleaching can lead to coral death and the subsequent decline of entire coral reef ecosystems.
Apart from high water temperatures, other factors that can contribute to coral bleaching include:
Increased solar radiation: Excessive exposure to sunlight, particularly ultraviolet (UV) radiation, can stress corals and exacerbate bleaching.
Pollution and poor water quality: High levels of pollutants such as sediment, nutrients (from fertilizers), and chemicals can weaken corals and increase their susceptibility to bleaching.
Ocean acidification: The absorption of excess carbon dioxide by the oceans leads to a decrease in pH, making the water more acidic. Acidic waters can hinder the ability of corals to build and maintain their calcium carbonate skeletons, making them more vulnerable to bleaching.
Extreme low tides: During low tide events, corals can be exposed to air for extended periods, causing them stress and leading to bleaching.
It’s important to note that climate change plays a significant role in the frequency and severity of coral bleaching events. The warming of the planet due to greenhouse gas emissions contributes to rising sea temperatures, making mass bleaching events more common and devastating for coral reefs around the world.
Log in to reply.