Coral reefs are extremely important to the health of the oceans. They are hotspots for biodiversity, and while they cover less than one percent of the oceans, it is estimated that at least a quarter of all marine life spends at least part of their life on a coral reef. If we lose reefs, then we are losing not just the organisms that inhabit reefs but also those that indirectly depend on reefs for survival.
Direct pollution, runoff from land-based sources of pollution, sedimentation from land development that can smother corals and other reef inhabitants, destructive fishing and over-fishing the oceans, and global climate change are probably the biggest threats right now.
Climate change will continue to negatively affect coral reefs, resulting in more mass bleaching episodes (loss or expulsion of the endosymbiotic algae that provide the coral with much of its food). And ocean acidification—the lowering of the pH of the ocean as more and more carbon dioxide is sequestered by the oceans—has the potential to be extremely detrimental not only to corals and reefs, but possibly every organism in the oceans, all the way down to the phytoplankton.
Unfortunately, the closer a coral reef is to human development and disturbance, the less healthy it often is, and there are often more cases of coral disease in these locations. As the human population continues to exponentially grow, the oceans will be taxed with more and more resources to provide, and they are running out.
We have to separate the stressors into local and global stressors and try to mitigate the local stressors so these ecosystems can have a better fighting chance at adapting to the global changes.
Educating yourself about and choosing sustainable seafood choices for healthy oceans, using reusable shopping bags instead of plastic bags, and supporting organizations and projects that are directly involved in coral reef conservation are just some of the things a person can do to help coral reefs.
I am involved in trying to help establish a captive population of corals that are declining throughout their Caribbean range, while my mentor, Mary Hagedorn, is working to cryopreserve the genetic material of these same corals. If these species go extinct in the wild, then we will not have lost them forever with our live banks in zoos and aquariums and the cryopreserved (frozen but alive) banks. In addition, we can potentially help with restoring these animals to the wild reefs using sexually reproduced colonies, as well as asexual fragments, if the conditions prove favorable. We will have learned how to grow them in a captive setting and can then transfer that knowledge to growing them up near their natal reef.
Corals themselves have been used in osteoporosis treatments and can replace human bone in surgery. However, there are millions of other animals that inhabit reefs as well, and many of them might very well be useful in bioprospecting. One of the drugs in the AZT cocktail that is used to help fight HIV-AIDS comes from a Caribbean sponge, while many snails have venom that can be used as pain relievers. With almost 95 percent of the oceans having yet to be explored, the potential for even more pharmaceuticals is extremely encouraging.
This is the apex of marine biodiversity, and it supplies much of the rest of the Indian and Pacific Oceans with genetic biodiversity, delivered by the ocean's genetic highways—currents. If we lose the Coral Triangle, we lose the most marine biodiversity the world has to offer.
Many corals sexually reproduce only once a year, though there are exceptions. Even then, if a coral larva (baby coral) defies the odds and settles as a new, primary polyp, it is probably only a few millimeters in diameter. The fastest growing corals grow only seven to ten centimeters a year, others grow only a few millimeters a year. If a coral gets hit with bleaching and a resulting disease, it can potentially lose that much living tissue in a day. It is possible to lose a 300-year-old coral colony in less than a month.
When water temperatures are elevated beyond the upper thermal limit for coral, it will bleach—expelling its endosymbiotic, nutrient-giving algae. This leaves the coral alive but starving. If the coral can recover, it may then put energy back into healing and growth rather than sexual reproduction. In addition, elevated temperatures have been shown to negatively affect coral larvae survival and also inhibit coral larvae settlement. This means that, as temperatures continue to rise, there are fewer and fewer baby corals replacing the ones that have already died.
They can be extremely useful in marine conservation. MPAs and no-take zones can be very useful in replenishing stocks of fish that have been overharvested. These can then seed other areas of the oceans (or reefs) that have been fished out. Often, the coral is more healthy in these zones, and they can reseed other reefs where the coral has declined. For many people in the world, their major source of income and their only source of protein is their reef. If they can protect their reef with a well-designed and protected MPA, then it can become a renewable resource for them.
I would explain that if he treats his reef as a delicate ecosystem that can be managed as a renewable, sustainable source, then the food and income he could receive from it will be much more bountiful in the long run—not only to him but his children and their children—than if he fishes with dynamite for just a day. It will take decades for that reef to recover from just one day of dynamite fishing. Where will he fish once all his local reefs have been destroyed?