Coral Bleaching

There are many stressors that are currently contributing to the decline and degradation of coral reef species worldwide, but the major driver is climate change, and more specifically, ocean warming. Climate change is defined as the change in weather conditions and patterns caused by biotic processes, variations in solar radiation, and increasing anthropogenic impacts.

One of the main factors affecting coral reefs currently is increasing sea surface temperatures. As we increase the amount of CO2 in our atmosphere, we're also increasing the amount of CO2 in our oceans. The ocean is a huge sink for CO2 which has caused sea surface temperatures to increase dramatically. 

Coral reefs are particularly sensitive to increasing temperatures because the symbiosis between corals and their marine algal symbionts begins to break down when water temperatures are high. As temperatures increase, the symbionts start producing toxins that are harmful to the coral species, which causes the coral to expel them from their tissue. This "coral bleaching" event, termed because coral species become white as the symbionts are lost, reduces the overall structure and function of the coral host. 

 

 

Bleached corals no longer receive the sugars and organic carbon the symbiont once provided and if corals live without their symbionts for extended periods of time, corals can die. Global mass bleaching events have become more frequent and widespread in the past few decades and are often associated with reduced colony growth, decreased reproductive capacity, and high mortality. Studies have shown that if these events continue to increase in frequency and severity, more than 90% of coral reefs worldwide will be degraded by 2050. 

 

Scientists have projected that carbon dioxide and temperatures are going to continue to increase over the next 50 years, up to levels that coral reef ecosystems have never seen before. If these levels are reached, coral reef ecosystems will become increasingly threatened and in danger of rapid decline. However, scientists believe that corals will begin to change and adapt rather than disappear. Some coral species are already showing signs of tolerance to increasing temperatures, providing some hope for the future of these ecosystems. 

However, we still need to understand just how corals are going to be able to adapt and therefore, researchers around the world are trying to find the answers - including myself! We all want to know how these various stressors are impacting corals, if corals can become resilient, and whether or not this resilience can lead to adaptation and evolution. Funding research like my own can help us understand and predict how corals are going to respond. In addition, my research will have the ability to pinpoint more at risk coral species for conservation and restoration programs as well as management plans.