Coral reefs are sometimes referred to as the “rainforests of the sea”. They’re hotspots of biodiversity and incredibly productive ecosystems. It’s hard to believe that such gigantic reefs, like the 1,400-mile-long Great Barrier Reef began with tiny invertebrate coral polyps, organisms related to sea anemones and jellyfish. These polyps attach themselves to a rock or hard surface, clone themselves, connect to one and other, and become a colony that acts like they are a single organism. Colonies also have the ability to join other colonies, creating massive coral structures.
Coral reefs have been in the news a lot recently, most notably because large parts of the famous Great Barrier Reef are dead or dying. Hundreds of miles of the northern sector of the reef have been found to be dead because of warming ocean water. This is one of three worldwide mass bleaching events on coral reefs since 1998, and this one has been the most detrimental. Only 9% of the Great Barrier Reef has avoided any kind of bleaching since 1998. While the news may present a grim outlook for our coral reefs, they are actually very resilient. However, when faced with multiple stressors at once, coral reefs can buckle under all of that pressure, and die.
Coral reefs face numerous threats, but many of them can and should be managed because reefs are so important to both the marine and terrestrial world. Coral reefs support more species per square mile than any other marine environment. This includes about 4,000 species of fish, eight species of hard corals, and hundreds of other species. Even more incredible is the fact that they cover less than 1% of our ocean floor and support 25% of marine life. While it is clear that coral reefs are critical habitat for many marine organisms, coral reefs are also pretty critical for humans.
The commercial value of U.S. fisheries from coral reefs is more than $100 million. In addition, there are approximately half a billion people that live within 100 kilometers of a coral reef and profit from its protection and its production. Hundreds of millions of people get their protein primarily from reef fish. Coral reefs act as barriers between shorelines and waves, preventing erosion and possible property damage. They also act as a buffer for coastal wetlands, ports and harbors. Many pharmaceutical drugs are developed from multiple animals and plants living on coral reefs. These reefs also provide critical economic and environmental services totaling approximately $375 billion per year. Healthy coral reefs can be an important part of local economies because of the tourism that often takes place on and around them, including diving, fishing, hotels, and restaurants. Reefs provide millions of jobs for people all over the world.
An amount of sunscreen that is the size of a water droplet and placed within an Olympic-sized swimming pool can have toxic effects on coral reefs. Avoid any sunscreen with the ingredient oxybenzone, and look for biodegradable or eco-friendly sunscreens.
Currently, around 25% of coral reefs worldwide are damaged beyond repair, and an additional 66% of coral reefs are seriously threatened. Scientists estimate that anthropogenic factors could kill around 30% of remaining coral within the next three decades. Coral is incredibly sensitive to changes in climate, and that is only one threat that they face. Large and powerful waves and weather systems like hurricanes and cyclones can break coral, and these types of weather systems will become more frequent as climate change worsens. Increased sea surface temperatures, linked to global warming, can cause coral bleaching, stressing out the coral and the algae that live in their tissues. The algae are where coral get most of their nutrients, which come from the byproducts of the algae’s photosynthesis. There is also land-based runoff and discharge filled with pollutants. This runoff and pollution often comes from dredging, coastal development, agriculture, and sewage treatment plants. When runoff or pollutants enter the ocean, the nutrient levels of the water will increase which can cause a spike in algae growth and that surge in algae growth can smother coral. Humans can also directly affect coral by being careless or untrained divers and touching or kicking the coral, which can cause it to break and die. In addition, deep-water trawling is a type of fishing that drags a weighted net on the seafloor, and this can damage entire reefs. There is also the issue of careless boaters who can drop their anchors directly onto coral reefs. A more recent issue that has come into the light is our sunscreen. A chemical often found in sunscreen, oxybenzone, was found to contribute to coral bleaching and can disrupt reproduction and the growth of corals.
Although it may seem like everything involving coral is very doom and gloom, that may not be the case. As mentioned before, corals are resilient, and if we can limit the stressors that might overwhelm them, they will have a much better chance of survival. So, what can you do to help? First, support reducing air pollution by driving less and relying more on walking, biking, and public transportation. Decreasing air pollution will help decrease the amount of greenhouse gasses that enter the atmosphere and contribute to global warming. Second, pay attention to what you are putting on your lawn and bear in mind that it can flow into the water system and pollute the ocean, despite whether or not you live close to the ocean. Next, dispose of your trash properly and pick it up if you see it on the beach. Trash can cover the reefs, or wrap around coral and break it. It can also be ingested by many reef animals and harm them. In addition, practice responsible diving and snorkeling by not touching the reef or anchoring your boat on a reef. You can also minimize runoff by planting trees or having a garden bed around your house.
Finally, check your sunscreen. According to the National Park Service, anywhere between 4,000 and 6,000 tons of sunscreen enter coral reef areas worldwide each year. An amount of sunscreen that is the size of a water droplet and placed within an Olympic-sized swimming pool can have toxic effects on coral reefs. Avoid any sunscreen with the ingredient oxybenzone, and look for biodegradable or eco-friendly sunscreens. If there is sunscreen on your body and you are over the reef, there will be sunscreen on the reef. Reach out to your government representatives and demand that coral reefs be protected from things like sewage pollution, sunscreen (Hawaii is currently trying to pass a bill banning oxybenzone sunscreen), expanding marine protected areas, and tackling some of the causes of global warming. Many things that negatively effect reefs are preventable.
While individual efforts will go a long way in helping mitigate some of the coral’s biggest stressors, science is also doing its part to help repair damaged coral reefs and help corals survive global warming. Some researchers are growing corals in nurseries and then transporting those corals to damaged reefs. This has been successful in the past. There is also some interesting work being done with helping corals evolve in a way that will make them more likely to survive in the environment they enter. This is still something that needs more research before it is fully implemented, but the idea is that researchers help produce corals that are better prepared with traits that will help them survive ocean changes. You can expose a coral to something stressful, so that they know how to best handle it in the future. These stressors include temperature and light so that they can hopefully be less sensitive to these factors and tolerate them when they are more extreme. Additionally, researchers believe it could be possible to evolve the algae that live on coral and pick algae that are shown to have higher heat tolerances. The idea behind this is that the algae would be raised in a lab under stressful conditions, such as high heat, and those that thrive would be introduced to corals. There are still plenty of questions and concerns about some of these techniques, but they do seem promising. With that said, individually decreasing out contributions to climate change is also paramount.
Coral reefs reflect how healthy our ocean is, so we need to pay attention to them. There is plenty that we can do to help save our coral reefs, both individually in our everyday life, and by supporting or participating in scientific research. We can play a huge part in limiting the amount of stressors coral reefs face, so consider changing at least one thing today that might help coral reefs, whether that be the type of sunscreen you use, or riding your bike to work. Coral reefs need us as much as we need them.