How to save the world‘s dying coral reefs





An article by Sebastian Rotter for Planet Rehab



Many people are aware of the important role that plants — especially trees — play in making this planet habitable for us humans. Deforestation, particularly in tropical rainforests, is one of the most prevalent topics when talking about the protection of the environment. While this topic is certainly deserving of its role in the foreground of many discussions, we must not forget another, much less visible part of the world’s ecosystem: coral reefs. Able to grow in depths of more than 300 ft, but most often found in water shallower than 230 ft, coral reefs occupy only 0.1 % of the area of the ocean while supporting 25 % of all marine species on the entire planet. Their biodiversity rivals that of tropical rainforests, such as the Amazon. Unfortunately, coral reefs are disappearing at an alarming rate everywhere in the world, both from direct destruction – like destructive fishing practices – and indirect destruction from increased ocean temperatures and changing ocean chemistry resulting from the warming of the globe. What can we do to slow the destruction of these valuable ecosystems and can we even help them recover?



Role of coral reefs – What are they doing for us?


Often called the rainforests of the sea, coral reefs provide around one quarter of all fish in our oceans with a food source, shelter from predators and a place to reproduce and rear their fry. However, it is not only the marine life that benefits from coral reefs. It is also us humans who benefit greatly from it. The most obvious aspect is that a loss of coral reefs would also result in a loss of a big portion of marine (fish) species, many of which play an important role as a food source for local communities in coastal regions. Naturally, this effect would also cascade into cities beyond the coastal regions and would greatly reduce the availability of fish as a food source for all of us in the world. Additionally, millions of people would find themselves without work, not only those people who are directly involved in the process of fishing, preparing and transporting the fish, but there is also a huge amount of recreational value in reefs, as diving and snorkeling on and near reefs can bring in a lot of revenue from tourism to otherwise poor regions and areas. The WWF reports in their Living Planet Report (2018) that the livelihoods of 10 – 12 % of the world’s population directly rely on fisheries and aquaculture, and 4.3 billion people are reliant on fish as 15 % of their animal protein intake. In fact, a report prepared by the Prince of Wales’ International Sustainability Unit (ISU) together with the United Nations Environment Programme (UN Environment) and the International Coral Reef Initiative (ICRI) published in 2018 estimates that a healthy coral reef scenario is expected to deliver additional economic benefits of around $35 billion in the Mesoamerican Reef in the Caribbean and the same amount in the Coral Triangle in SouthEast Asia, the two case study regions for the report, in the timespan of 2017 to 2030.


It is important to mention another crucial role that coral reefs play that benefits us humans: they provide a buffer zone that protects our coasts from waves, storms and floods. According to the WWF Living Planet Report, nearly 200 million people worldwide depend on coral reefs to protect them from storms and waves. Without them, many beaches and buildings would become vulnerable to incoming waves and storms, which are predicted to become even stronger in the future due to climate change. Without those reefs, we would have to build fortifications ourselves, which can have astronomically high costs, as can be seen in the example of the Maldives, where after mining away corals and sand, a protection wall needed to be built along the coastline which cost $10 million per kilometer to build.



Threats to coral reefs – Why are they disappearing?


Coral reefs are subject to a plethora of different threats coming from both natural as well as human origins. Natural threats mostly come from weather-related phenomena such as hurricanes and cyclones, which result in large and powerful waves that can devastate whole reefs at once. Furthermore, increased sea temperatures, changes in the sea level and changes in salinity can be the result of weather patterns such as El Niño. Lastly, if certain predator populations become too high, such as those of certain fish, marine worms, crabs and snails, the riffs can also be gravely damaged. However, coral reefs may recover from periodic damage caused by these natural occurrences if given enough time to recuperate. If they are subjected to sustained stress, for example because of human influence, their natural ability to recover can be disrupted.


We can list multiple factors under the human influence on coral reefs. Most notably, they are (i) pollution, (ii) overfishing and the use of destructive fishing practices such as using dynamite or cyanide, (iii) the collection of live corals to be used in aquariums, (iv) mining corals as a building material, (v) careless tourism where people touch and break off pieces of the reefs and stir up sediment, (vi) construction projects, e. g. the construction of harbors, tourist resorts etc., that lead to a direct destruction of coral reefs as well as to increased erosion of soils and other substances from the ground. These end up being carried away through rivers into the ocean where they can suffocate reefs.


Thus, we can clearly say that human activity is the deciding factor in the destruction of the coral reefs and their inability to recover properly. While the direct destruction of the reefs can be identified very easily as an obvious reason for their disappearance, the change in our global climate is a more hidden killer, but is ultimately the factor that poses the biggest risk to the survival of our planet’s coral reef ecosystems.





Figure 1: Illustration of 'bottom trawling' - An extremely damaging fishing practice that can destroy more than 90 percent of coral colonies in the area. Found on usa.oceana.org.



Restoring coral reefs – What can we do?


So, if we are the main reason for the destruction of the world’s coral reefs, is there also something we can do to restore them or to help them recover? Thankfully, the answer is ‘Yes, we can!”.


The main idea that has already led to great success stories in the restoration of some coral reefs revolves around one of the two ways that a coral can reproduce. They can reproduce sexually as well as asexually. Their asexual reproduction method is also called coral fragmentation. In favorable conditions or through external influence, such as strong currents, a branch can break off from a coral and fall onto the reef or get swept away by the current to another location, where it can reattach and start growing a new colony. We can use this natural process to create coral farms, where we break off parts of a healthy coral, nurture it to help it grow, and then – once it is big and strong enough to live on its own in the ocean – we can transplant it onto the ocean floor where a new coral colony will be established. These coral farms can look a little different depending on the project. It is possible to grow the corals directly in the ocean, so that they are very close to the area where they will establish new colonies, or in saltwater ponds that emulate the conditions of the ocean, or also in a laboratory setting where they are grown under very controlled conditions. Laboratories make accessing and checking on the corals much easier on the one hand, but on the other hand it will be more difficult to emulate the living conditions in the ocean.


Coral fragmentation offers another major advantage over the natural reproduction of corals: it has shown to be substantially faster to grow corals via fragmentation – up to as much as 25 times as fast. This means that corals can be grown in weeks and months, compared to years. Typically, a coral will take anywhere between 25 to 75 years to achieve sexual maturity, whereas using coral fragmentation, this time can be cut down to just three years.


Typically, the corals are given a structure to which they can cling, so that they are not swept away by currents. This can be realized in different ways. The picture below shows the use of Coral Trees which are tethered to the ocean floor and buoyed with a subsurface float. Not all coral species are equally well-suited to be grown this way, but there are many different ones that are very accepting of this approach.





There are many different organizations that have made it their missions to repopulate our destroyed coral reefs with new corals that have been grown in this manner. Planet Rehab is one of those organizations that - among many other projects - are working on saving the extremely diverse and important coral reefs in the area of Bocas del Toro in Panama, Central America. For that reason, Planet Rehab is constructing a saltwater pond that will use the above mentioned fragmentation (also fragging) process to grow small fragments of old corals into new and healthy corals that can then be transplanted into the ocean floors of the region. This project will depend on continuous research in order to identify which corals are best suited for this region and will have Planet Rehab work alongside other organizations to find the best ways to save and preserve the coral reefs that are still healthy in the region. For more information on the coral restoration project in Bocas del Toro and for means to support Planet Rehab, see also planetrehab.org.



Resources









The Prince of Wales’ International Sustainability Unit (ISU), United Nations Environment Programme (UN Environment), International Coral Reef Initiative (ICRI), S&P Trucost Limited (2018): The Coral Reef Economy - The business case for investment in the protection, preservation and enhancement of coral reef health.



WWF (2018): Living Planet Report – 2018: Aiming Higher. Grooten, M. and Almond, R.E.A.(Eds). WWF, Gland, Switzerland.









Andrew C. F. Taylor (2018): Nusa Islands Restoration Project – Bali Indonesia. Blue Corner Marine Research.