This week is Coral Reef Awareness Week, a time to educate people about these amazing and diverse marine ecosystems and the threats they are currently facing. So let’s take some time to learn a bit more about coral reefs and how to protect them!
What’s a Coral Reef?
To answer this question, you first have to know what coral is. Coral are tiny invertebrate animals, related to sea anemones and jellyfish, that live together in colonies. Over time, these organisms create a single unified skeleton that serves as a kind of home for coral colonies. These skeletons can vary greatly in terms of shape and size depending on the type of coral. Some are large and round, others are shaped like the antlers of a deer, some look like large flat fans, and others look like human brains!
As many corals in an area congregate and create their exoskeletons, they form a large ecosystem called a reef. These reefs become home to an incredible amount of diverse marine species, attracting fish, invertebrates, algae and even seabirds. Though the total surface area of coral reefs is a very tiny amount of the ocean, about one tenth of one percent, these reefs are home to one quarter of ocean species. Coral reefs are full of diverse and brightly colored organisms, earning them the nickname “the rainforests of the sea”.
|An assortment of coral reef creatures (and a treasure chest!) from our Coral Reef TOOB|
Where Are Coral Reefs Found?
Coral reefs are actually not that old, in the grand scheme of life on Earth. Many of them were formed after the last Ice Age ended, a little over ten thousand years ago. As the ice melted and sea levels rose, reefs were able to form in places that previously did not have enough water to form them. Reefs are usually found near shores or around islands, or on the continental shelf, which is the offshore area around continents where the shallow water drops off into the deep sea. Sometimes, coral reefs form around an island that eventually sinks below the surface. The reef then remains and becomes what is known as an atoll.
Common Coral Reef Dwellers:
|Spiny Lobster||Pufferfish||Moray Eel|
Coral reefs are fragile ecosystems that depend on many ideal conditions, including proper temperature and sunlight. This is why most coral reefs are found in shallow, tropical waters. There are some coral reefs in deep, colder waters, but they are much rarer. The largest coral reef of all time is the Great Barrier Reef, which is found off the coast of Australia and stretches over 1,400 miles long. About 90% of coral reefs are found in the Indo-Pacific Ocean, while the Atlantic and Caribbean contain about 7% of the world’s coral reefs. The rest are spread across islands and shallow waters throughout the world.
What Creatures Live on Coral Reefs?
While they are very fragile, reef systems home to an incredible array of marine life. About 4,000 different types of fish are found in coral reefs, including sharks, moray eels, pufferfish, stingrays, clown anemone fish, and much, much more.
|Whitetip Reef Shark||Clown Anemone Fish||Reef Squid|
Coral reefs also attract many invertebrates, including reef squids, spiny lobsters, nudibranchs, octopuses, clams, sea anemones and many others. Reptiles such as sea turtles and sea snakes also call the reef home, and even saltwater crocodiles have been known to visit reefs from time to time. Seabirds including pelicans, blue-footed boobies and several species of albatross also frequent coral reefs in search of fish to eat.
What Threats Do Coral Reefs Face?
As we’ve mentioned, despite housing some of the richest biodiversity in the world, coral reefs are fragile, and throughout the world many coral reefs are dying off. They face many threats both local and global, and urgent action is needed to ensure that coral reefs will be around for future generations to enjoy and appreciate.
Chemical pollution, overfishing and canal digging are all localized threats that harm reefs and the life forms that depend on them. Anchors from ships can also damage coral, as can marine debris, especially plastics like fishing nets and other garbage. Invasive, non-native predators can also damage corals.
|An assortment of coral reef creatures from our Coral Reef Good Luck Minis Fun Pack|
Coral bleaching is a another serious issue that many reefs face. Bleaching happens when corals push out the algae that lives within their exoskeletons. The corals turn white and, if the process is not reversed, the corals will die. Many factors are responsible for coral bleaching.
- Sunscreen with oxybenzone, a common ingredient in many sun-blocking lotions, harms many types of animals and can cause coral bleaching. In addition to entering the ocean water from the skin of humans, it is also flushed out to sea in waste water after humans wash it off.
- Sea level rise due to climate change can also lead to coral bleaching. Many coral reefs are positioned in a “sweet spot” where the temperature and access to sunlight is ideal for coral growth. Rising sea levels put existing reefs further from necessary sunlight, and can also caught temperature changes, both of which puts a lot of stress on coral.
- Warming waters due to climate change can also lead to coral weakening that makes them more susceptible to diseases. Bacterial infections can lead to coral bleaching.
- Increases in carbon dioxide gas emissions, much of which gets absorbed by the sea, causes what is known as “ocean acidification”. As the ocean acidifies, coral bleaching can occur.
- Overfishing can lead to explosions of plankton, which fish normally eat. Without the fish to eat them, the plankton can use up all the oxygen in large areas of water, and without enough oxygen, coral can undergo bleaching.
Though coral can recover from bleaching, it can be deadly if not addressed quickly. Due to rising temperatures, global bleaching has been occurring at high levels since 2014, majorly effecting reefs all over. Reefs off of South Florida have shown about two thirds of their corals dead or dying, and as of 2017, it is estimated that 75% of Japan’s largest coral reef has been killed off by bleaching.
More Common Reef Dwellers
How Can We Save Coral Reefs?
All is not lost! There are many people out there today working hard to halt and reverse the damage being done to coral reefs. But it’s a group effort, and more people will need to change their behaviors for coral reefs to truly be safe.
You can start by switching to a sunscreen that doesn’t use oxybenzone. Mineral based sunscreens are less harmful to coral. Check out this list for a good selection of sunscreens without oxybenzone. States such as Hawaii are already starting to outlaw lotions with oxybenzone due to the damage it is causing to their essential reef systems.
The establishment of Marine Protected Areas (MPAs) is another way that damage to reefs can be lessened. By limiting or prohibiting fishing and other harmful activities in these areas, reefs can be given time to recover and grow.
Coral nurseries can also help reefs bounce back. Introducing coral grown in “nurseries” back into the wild reef system helps coral spread, grow and recover. The MOTE Marine Lab is just one of the organizations working on different restoration techniques, including a method of growing new corals from damaged coral fragments.
Above all though, halting the progression of climate change is essential to halting the decline of coral reefs. Climate change causes both sea level rise and ocean warming, both of which severely damage reef systems and lead to bleaching. Carbon dioxide gas, which speeds up climate change, also acidifies the ocean and harms reefs. Ultimately, taking steps to reverse or slow climate change would likely have a huge positive effect on reefs throughout the world.