Rebuilding more Resilient Coral Reefs

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Florida Fish and Wildlife
A Mote team prepares corals for outplanting.

Our oceans are vast, mysterious, full of natural beauty, and vital to life on earth. The oceans drive our weather patterns, keep our air clean, and provide the foundation of a complex food web that sustains life as we know it. With so much depending upon the oceans, it is hard to believe that we know more about the surface of the Earth’s moon than we do about what lies beneath the surface in this amazing marine ecosystem. Partly, what makes our oceans such incredible places are the animals and organisms that inhabit them. Some of the most complex and interesting of these are corals.

Hard corals live in dense colonies made up of hundreds or thousands of individual polyps connected by living tissue. A coral polyp has one of the most interesting symbiotic relationships we know of in our oceans because it’s comprised of a plant, algae which is what gives it color, an animal, the coral itself, and a bacteria which serves as an antibiotic coating that protects the coral from disease and certain types of predation. The algae create a photosynthetic reaction to sunlight which creates energy that feeds the bacteria, while the coral itself feeds on microorganisms floating by in the currents and tides. The result is the production of calcium carbonate, which gives corals their shape and creates the hard surfaces and structure that we know as a coral reef.

Coral reefs make up less than one percent of our oceans and yet, despite their small size and sea floor coverage, more than 4,000 species of fish, and as much as 40 percent of marine life worldwide depend on coral reefs at some point in their life cycle.1 Whether for spawning, nursery grounds, refuge, or forage, coral reefs play a key role in the health of our oceans and of the planet as a whole.

Sadly, in the past 30 years, 25-40 percent of all corals worldwide and 92 percent of the branching corals indigenous to Florida and the American Caribbean have perished due to climate change, pollution, ocean acidification, and disease.2 With such disturbingly low numbers remaining, recovery without help from humans is extremely unlikely and probably would not occur in our lifetime.

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Mote POR 2014
Outplantings of staghorn corals.

However, there is hope. Scientists and researchers at Mote Marine Laboratory in Florida in the US have made some exciting discoveries and breakthroughs over the last seven years that appear to be a potential answer to save our dying coral reefs. Through processes called coral fragmentation and micro-fragmentation, researchers have found that corals, which grow very slowly and only reproduce roughly once per year, can actually grow very quickly when cut down into small pieces. Branching corals, such as staghorn and elkhorn, when fragmented into one- to two-inch pieces will grow very rapidly and will nearly double in size over just a couple of months. In only 6 to 12 months, reef building corals, such as brain, boulder, and star corals, when cut down into fragments of just two to three polyps, respond with growth rates of 25 to 40 times what occurs in a mature colony. When these corals are outplanted back to reef areas where their ancestors once thrived, the corals quickly stabilize, affix themselves permanently to the hard substrate, and begin to grow rapidly to a mature size. The results have been nothing short of amazing and the survival rate of these outplanted corals is more than 92 percent after three years in the wild.

Human skin grows relatively slowly, however, when cut or injured, it grows extremely quickly as a healing response and overall physiological survival instinct. Corals, when cut into smaller fragments, have demonstrated a similar response by growing as fast as they can in order to both heal and compete for space to survive in the marine ecosystem.

The outplanted branching corals grow upwards and outwards into dense thickets, and immediately begin to attract fish and a wide variety of marine life. Juvenile fish, fingerlings, crabs, shrimp, and a whole host of critically important marine animals now have some cover from predators once again and this helps to bolster overall fish populations and biomass. The food web begins to expand and the ecosystem once again comes alive with diversity and volume that we have not seen in many decades.

The reef building corals are planted just a few inches apart in an array of between 10-20 pieces. As long as they are fragmented from the same genetic parent, once they get close enough to touch, they recognize each other as a member of the family and merge together. This tissue merge, now called coral “reskinning,” makes it possible to restore what might have taken 50-100 or 1,000 years to occur naturally, achieving that same growth within two to three years.

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Florida Fish and Wildlife
The Mote team works to outplant corals, which are arranged in close arrays of 10-20 corals. Once close enough to touch, they will then merge together.

The question most often asked is: why won’t these newly restored corals simply perish like the rest of them have done over the last 30 years? It is a valid concern that the researchers at Mote have taken on in a very innovative way. The corals that still exist in the wild today appear to have survived the changing sea conditions that have been responsible for wiping out more than 90 percent of their species to this point. From this, it is now understood that corals are similar to humans and other organisms which have varying tolerances to disease, habitat change, temperature, etc., and corals, just like humans, have varying genetic qualities and traits within the same species that allow some of them to survive in today’s changing oceans.

It is because of this varying genetic tolerance, and what is hoped to be continued adaptation, that the scientists at Mote feel they have a potential answer to restoring our precious reefs. To take this a step further, the Mote team, addressing the fact that our oceans are becoming more acidic as the CO2 levels in our atmosphere rise, is looking at how corals might adapt and survive ocean acidification in the future by creating those future sea conditions in a lab setting and subjecting the currently living corals to tests in these conditions. The findings have been encouraging as they have found that certain genetic subsets are much more tolerant than others in warmer and more acidic seawater. Naturally, the more tolerant corals are the ones being used, at this point, for replication through fragmentation. Additionally, to avoid the chance of in-breeding, this restoration program uses more than 45 different genetic subsets of the same species, putting them in close proximity to similar reef areas. This means that when these newly outplanted corals mature and begin to reproduce, they are enhancing the likelihood of carrying on some of the genetic material that has allowed them to survive in more acidic and warming waters.

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Mote POR 2014
A nursery of staghorn coral posts and trees, planted by the Mote team.

Today, conservation of our oceans is a top-tier concern for the health of our planet as the state of our oceans affects each and every human in some way. Our corals and coral reefs are keystone elements of our marine ecosystem, helping it thrive, and the decline in their health is a warning sign that something needs to be done. Corals and coral reefs are also critical in maintaining a strong domestic economy. According to the NOAA (National Oceanic and Atmospheric Administration) and the US Department of Commerce, reef-related activities generate approximately US $6 billion in revenue in South Florida and more than US $15 billion statewide annually, with both the commercial and recreational value of the fisheries supported by coral reefs amounting to more than US $750 million annually in the Florida Keys alone.3