It seems like corals should have everything sorted then, right?  They’ve got a nice stony shell in a lot of cases, they can breed in a way that spreads their genetic material across the ocean, and they have plenty of friendly species hanging around looking out for them.  The problems arise from issues that all the snails in the ocean can’t defend against, mainly rising water temperatures and ocean acidification linked to rising carbon dioxide levels.

The Heat is On

High water temperature can cause corals to lose the important algae that corals use for food, a process you might have heard of called “coral bleaching,” which when left unchecked can kill a colony, and even break down the reef. In addition to the threats posed by climate change, coral reefs face dangers from over-fishing, over-harvesting of coral itself, boat anchors or fishing gear dragged through delicate reefs, and pollution of the oceans by both industries and individuals, to name a few.

Too Much Acid

Ocean acidification is the process by which carbon dioxide uptake changes the pH of the earth’s oceans.  If you didn’t already know from your science classes, pH stands for “potential of Hydrogen”, and it represents the level of acidity or basicity of a given solution (whether something is acidic or not). Normally, seawater is considered slightly “basic,” which means it’s pretty neutral on the pH scale.

However, as the oceans absorb more carbon dioxide from the environment, it changes how the oceans chemical balance and causes the formation of carbonic acid.  This is bad news for everything living in the water because it damages immune systems, depresses metabolisms, and causes the coral bleaching mentioned above. This is a real problem, because it’s bad enough when a single group of animals is harmed, but as we’ve been discussing, when you kill a coral reef, you kill an entire ecosystem – everything that relies on that reef system!

Local Threats

In addition to the threats that face coral all over the world, specific reefs have troubles of their own. Tremendous damage can be done locally by pollution, which can take the form of fertilizer or pesticide runoff, sewage, and various chemicals, to say nothing of trash and micro-plastics. Reefs can be physically damaged by boat anchors, coastal development, and destructive fishing practices. Similarly, sometimes tourists touch or even remove parts of coral, which is obviously detrimental.  Overfishing can upset the balance of the ecosystem, which has a cascading effect. 

Conservation

Coral reefs face all these terrible threats.  Is there any good news? As a matter of fact, yes. Many countries have taken steps to protect their coral reefs. More than 150 operations are growing nursery-raised corals and transplanting them to degraded reefs just in the Caribbean.  

One inspiring success story comes from a remote Pacific island in the American Samoa chain. In 1978, almost 90% of the coral on Tutuila was killed by a crown-of-thorns starfish outbreak. The islanders took multiple steps to prevent further decline and to encourage the coral to regenerate. They established a marine sanctuary and put strict restrictions on fishing and the dumping of pollutants in the area. They banned spearfishing on the reef, leading to an increase in parrotfish, which eat harmful algae. As a result of these steps, the coverage of living coral has been steadily increasing since the eighties, with a jump from 25% to 36% between 2009 and 2018 alone.

In addition to big projects, there are things that all of us as individuals can do as well. Conserve water. The less water you use, the less runoff and wastewater that will eventually find its way back into the ocean. Volunteer in local beach or reef cleanups. If you don’t live near the coast, get involved in protecting your watershed. Become an informed consumer and learn how your daily choices such as water use, recycling, seafood, vacation spots, fertilizer use, and driving times can positively (or negatively) impact the health of coral reefs.

Reefs are more than just beautiful places for us to visit. They are necessary ecosystems for our entire world. It’s up to us to take care of them.