Effects on climate change were first recognized on coral reefs. Climate change affects coral reefs in many ways. Increased intensity of tropical storms and increasing ocean acidification both have a negative effect on coral. Bleaching refers to the whitening of zooxanthellae organisms due to the loss of the symbiotic relationship between corals and zooxanthellae. Since 1964 scientists have found 7 major bleaching events affecting corals. The threat of climate induced bleaching has caused many scientists to look into associations between zooxanthellae and their host corals.
Scientists have found that coral bleaching almost always results from declines in zooxanthellae densities. They have also found there are many causes to coral bleaching such as aerial exposure, cold shock, insecticide, pollutants, sedimentation, and of course temperature changes. Researchers have found that during bleaching events corals must rely on stored energy or utilize heterotrophic feeding to stay alive.
Severe bleaching usually results in the mortality of the coral because the animal tissue that house the zooxanthellae become damaged. It looks as if more research must be conducted to account for natural variation of zooxanthellae and bleaching events that cause lower levels of zooxanthellae in coral.
There are many natural occurrences that give way to mortality of coral such as seasonal and depth related differences in zooxanthellae densities. Scientists have found it is important to distinguish between families of coral when assessing natural densities of zooxanthellae because some types of coral have naturally low levels of zooxanthellae.
It has also been found that some coral species are more susceptible to coral bleaching than others. Scientists know that coral bleaching is disturbing whole reef ecosystems and the health of coral reefs worldwide is expected to decline. From the various articles discussing coral research I have learned we as teachers should follow in the footsteps of research scientists and educate our students as they educate about our everyday behavior that is attributing to the degradation of our precious coral reefs. I will be sure to involve my students in the incredible importance of learning about our coral reefs.