Coral reef bleaching occurs when corals become stressed and expel the zooxanthellae that lives inside them. Zooxanthellae is a type of phytoplakton that lives inside the coral and gives it its often bright color. When the zooxanthellae are expelled the coral turns white, hence the term “bleaching”. The Zooxanthellae is important because it gives the coral the nutrients it needs to survive (byproducts of the photosynthesis the plankton partakes in). So, when the zooxanthellae is no longer there the coral can not get the nutrients it needs to survive.
The reason this is such a pressing issue is because of what stresses the plankton. Rising sea water temperatures, ocean acidification, and pollution are some of the major stressors. Coral bleaching is happening at an alarming rate as these stressors become more prominent. There is little to do once a coral undergoes coral bleaching because it ultimately causes the death of the coral. Coral bleaching is being seen all around the world, including in much of the great barrier reef. Coral bleaching not only kills the coral but also strips countless other organisms of their homes. Coral reefs are some of the most diverse ecosystems on the plant, with numerous species taking up residency there.
However, there are some things that people are doing to help however. Artificial reefs are being created, but making structures to act as substrate and attaching coral grown in aquaculture facilities. These corals attach to the artificial substrate and begin to create new reefs. Structures like old planes, trucks, and cement shapes are also sunk to act as a substrate for young coral.
