If you’ve experienced prolonged stress, you know the toll it can take on your mind and your body. It can even cause your hair to lose its pigment, as the stem cells which produce melanin are damaged and lost. Believe it or not, something similar happens to corals under stress – coral bleaching. It causes coral reefs to go from the vibrant ecosystems teeming with life. Typically what we envision, to pale, white skeletons of themselves. Bleached corals are not dead, but they are more vulnerable to disease and if conditions don’t improve. The are at a greater risk of mortality.
Plant or animal?
There are many species of coral, but they can generally be classified as hard or soft. Hard corals or stony corals, produce a calcium carbonate skeleton, whereas soft corals look more like grasses or bushes. You may think corals are plants, or even rocks, but they’re actually sessile animals!
Each coral is actually a colony of many thousands of tiny animals called polyps. These polyps have a mutualistic relationship with a type of single cell algae called zooxanthellae that live inside of their tissues. These microscopic algae capture sunlight and convert it into energy, just like plants, to provide essential nutrients to the corals. In exchange, they have a place to live inside the animal’s body. But when the zooxanthellae are under stress, such as high temperatures, they will die or leave their host—a process known as bleaching.
Climate change is causing warming ocean temperatures. It is one of the leading causes of coral bleaching. Others include, changes in sunlight exposure, over-exposure to air during unusually low tides, over-fishing and the presence of pollutants such as run-off.
Plastic waste – What’s the problem?
Plastic waste is another culprit. Plastic debris is a growing threat to coral reef ecosystems, since it can accumulate throughout food chains, damage reef structures, and increase disease transmission. A recent study found human-derived debris was present in nearly all locations (77 reefs out of 84), including some of the planet’s most remote and pristine coral reefs, such as those adjacent to uninhabited islands in the central Pacific.
Scientists have found that once a coral has had contact with plastic debris, their risk of disease is multiplied by 20. Plastic pollution can block light for corals causing structural damage, increasing the chance of disease transmission throughout reef ecosystems. Moreover, once corals have lost their relationship with the zooxanthellae, they start to rely on consuming zooplankton for their nutrition. These are microscopic animals which float in the water. Similar in shape and size to microplastics, they can be mistaken by coral as tiny pieces of food. Also, microplastics, which are already made of chemicals, can pick up pollutants and harmful microorganisms from the seawater and transfer them to the coral.
Do coral reefs matter?
Coral reefs are immensely important for marine ecosystems and human livelihoods. More than 25% of marine wildlife depends on coral reefs during their life cycle, making them major hubs for biodiversity. Additionally, coral reefs protect coastal areas from storms and erosion, as well as provide local communities with food, jobs and incomes from tourism and fisheries. Even drugs are now being developed from coral reef animals and plants as possible cures for cancer, arthritis, human bacterial infections, viruses, and other diseases.
How can YOU protect coral reefs?
Regardless of where you are, you can help protect our remaining coral reefs through eco-conscious lifestyle choices. Properly disposing of rubbish helps to keep litter out of the ocean.
Avoid touching coral.
Check the ingredients of your sunscreen and ensure it does not contain oxybenzone and octinoxate. Even better, wear a long-sleeved shirt or rash guard to prevent sunburn.
Reducing your environmental impact, whether it’s by cutting down on your personal plastic consumption. Or, by choosing sustainable travel all helps to cut greenhouse gas emissions. Collectively, it would make a huge positive change to the health of coral reefs.