About fifty miles (eighty kilometers) off the coast of Venezuela lies Bonaire, the “B,” in The ABC islands (Aruba, Bonaire, and Curaçao).

There isn’t much to see on Bonaire, the capital Kralendijk is about three blocks long. The island is flat, warm, dry, and humid. The only notable wildlife are flamingos. In the evenings they can sometimes be seen gliding through the sky like fast-moving sunset-pink clouds, winging to Venezuela for a late supper. There are also a few anoles, giant iguanas, donkeys, and goats, most of whom will eagerly accept handouts from tourists.

Bonaire is fringed by coral reefs, which are easily accessible from the shore. Unlike most dive destinations, where divers require a boat and a dive master, in Bonaire all they need is a tank and a truck. Divers can suit up, with their buddy, and dive almost whenever and wherever they want to. Minimal currents and shallow depths make for very safe conditions.

Bonaire is famous, not just for its reefs, but for its protection of them. In 1979, the entire coastline of the island was designated a marine sanctuary, from the high-water mark down to a depth of two hundred feet (sixty-one meters), including a large mangrove forest.

Still, Bonaire is not impervious to the inevitable desire for more tourist dollars and more money. At least one cruise ship is usually at the port and expanded growth, if not properly monitored, is a very real danger.

In November 2021, Chogogo Resort Bonaire, a TUI franchise project, was fined $1.2 million, and construction was temporarily halted. Chogogo had illegally imported and dumped three thousand five hundred tons of sand from French Guiana without obtaining permits, testing the sand for diseases, parasites, or bacteria, or constructing a protective seawall. As a result, sand washed onto the nearby reefs, smothering many corals.

In addition, numerous diseases have proliferated over the last ten years, causing widespread mortality among reef-building corals. This is probably related to deteriorating water quality, pollutants, and increased ocean temperatures, which may allow for an increase of disease-causing microbes. However, the exact causes for most coral diseases remain elusive.

Coral reefs cover only about one percent of the ocean, yet they are home to more than twenty-five percent of ocean life, a large fraction of Earth’s biodiversity. Miles and miles of uninhabited salty, blue waters stretch into seeming infinity without many visible signs of life, except for small patches of coral reef. On a reef, everything is alive. Things that look like rocks or plants turn out not only to be animals, but massive colonies of animals that photosynthesize and build rock houses. Hard corals that make up the substructure of the reef may look like beautiful, soft, colorful rocks, but they are animals.

Why do we need coral reefs?

Besides the fact that they are beautiful, biodiverse hot spots?

• Hard corals, such as staghorn and elkhorn, provide a bulwark against hurricane and tidal damage, and these threats are increasing due to climate change.
• Reefs generate jobs for many small island states that have few alternative sources of income.
• Corals are often called the rainforests of the ocean. They are unexplored panoplies of medical compounds.
• Perhaps most importantly, coral reef are nurseries, without which juvenile fish will have no place to mature.

Once ensconced in their bungalows on the reef, corals ingest a tiny free-floating alga called zooxanthellae (Zoo-Zan-Thella) that lives inside them and supplies ninety percent of their food, as well as their brilliant coloring. It’s as though when we ate brussels sprouts, instead of digesting all of it, we incorporated its chloroplasts into our cells to photosynthesize food, and it tinted our hair and hands green. (Chloroplasts are the cells that carry out photosynthesis, converting light to sugar.)

In a kind of symbiosis called mutualism, the corals provide the zooxanthellae a home and a constant supply of the carbon dioxide needed for photosynthesis. This mutualistic relationship is strongly dependent on temperature. When the water grows too warm or polluted, zooxanthellae are expelled from a coral’s tissue, causing it to lose its color, and a major source of food. This is known as “coral bleaching.”

Coral bleaching does not always mean the death of a reef. Corals can recover their zooxanthellae, but the process requires cool temperatures and clean waters. Warming temperatures and bleaching are only a few of the threats to reefs. Bonaire is a protected island, so it doesn’t have to face issues like cyanide fishing, overfishing, net trawling, and coral mining that many places do. Nonetheless, Bonaire is not without problems.

In 1977, white band disease decimated populations of staghorn (Acropora cervicornis) and elkhorn coral (Acropora palmata) throughout the Caribbean.

Damaged staghorn reef at Margate Bay. Photo: Dan Bender

In 1983, a mysterious epidemic spread through the Panama Canal, into the Caribbean, killing off ninety-eight percent of all sea urchins (Diadema antillarum). Sea urchins are critical to coral reefs because they eat coral-smothering algae. And yet, algae too are needed. The ocean and earth are made of interlocking, interdependent pieces, damage one and the puzzle collapses.

In addition, warmer oceans are more acidic, making it difficult for corals to build their hard exoskeletons. And climate change doesn’t just mean warmer, more acidic waters, it also means bigger storms and worse hurricanes, that break and destroy more reefs.

Once thought of as a boundless resource, these coral species face near extinction, due to many and varied anthropogenic impacts. Between eighty to ninety-eight percent of elkhorn and staghorn coral are gone. Staghorn and elkhorn corals are listed as critically endangered by the IUCN Red List of Threatened Species, and this year twenty more species of coral joined the threatened list. But don’t despair. Reef Renewal Foundation Bonaire (RRFB) offers hope!

Our environment is changing too quickly for coral reefs to survive without our help. There are solutions to these problems, but we need a global network to put these solutions into practice. Reef Renewal Foundation International is growing such a network, providing the link between science and global action. Their projects vary in size and capacity but are all united by one common goal—to restore coral reefs using simple, easily reproducible techniques supported by science, demonstrating that there is still hope for the coral reef community.

It started in February 2012, when Ken Nedimyer, Founder of Coral Restoration Foundation and “the father of coral restoration,” helped one local dive shop on Bonaire start a reef restoration project. It was just a few corals, dangling from a PVC pipe tree in a dying sea.

Today, over fifteen thousand corals are grown in RRFB’s ten nurseries and over forty thousand corals from seventy-six different genetic strains have been outplanted back to Bonaire’s reefs.

RRFB is mostly focused on staghorn and elkhorn coral. These can be grown by fragmentation. This method is based on the asexual reproduction of corals and allows them to propagate large numbers of corals without harming the wild populations.

The teams use low-cost, easily available materials and techniques that are simple to repeat and replicate. They hang corals on “trees” of PVC pipe with fiberglass rods running through the trunk. These rods are tethered to the bottom with anchors and buoyed with floats. This allows free movement within the water column, allowing the trees to weather storms.

Each coral morphology is different and therefore there is no “one size fits all” approach. Depending on the species, corals are either hung from the branches of the trees or secured on trays.

Staghorn hanging from a coral nursery. Photo: Beth Watson

The coral nursery trees need constant cleaning to remove algae and fire coral. When they get big enough, they are outplanted, once again, using different methods for different corals. Staghorns are wedged together and elkhorns are glued to rocks.

The author & author’s husband, Kevan, cleaning elk and staghorn coral. Photo Dan Bender

Like most scientific work, the nuts and bolts are simple and repetitive, cleaning algae and scraping fire coral off the coral trees. But as one scrapes, large Spanish hogfish (Bodianus rufus), surgeonfish, puffers, and wrasses keep the workers company, hanging out and eating the debris. When the corals are ready to be planted, damselfish and a variety of other creatures eagerly await the fitting together of staghorn corals. They move in as soon as the corals are placed.

In addition, RRFB is involved in larval propagation—using coral sexual reproduction as a restoration method. This increases the genetic diversity of corals on reefs. Genetic diversity increases the chances of producing corals capable of coping with rapidly changing conditions. Although Bonaire’s coral reefs feature significant populations of coral species, the healthy colonies may be too far apart to reproduce successfully sexually, limiting the formation of new genetic strains. For this reason, assisting the sexual reproduction of coral through larval propagation is critical to aid the recovery of degraded populations.

Every year, colonies of coral simultaneously release their tiny eggs and sperm, called gametes, into the ocean. Billions of tiny pink eggs rise through the night sea. Mature corals all release their gametes at the same time. The gametes rise slowly to the ocean surface, where fertilization begins. This synchrony is crucial because most of the gametes are viable for only a few hours. It also increases the chances of fertilization and helps combat predation. Using nets placed above the spawning colonies, divers collect the gametes and bring them to RRFB’s on-land lab facility. Once on land, the team mixes gametes of genetically different coral colonies of the same species to assist the cross-fertilization. Coral larva, called planula, are carefully monitored as they develop.

Fragmentation allows RRFB to outplant bigger colonies and quickly restore reefs with corals that will reach maturity and begin spawning in just a couple of years. However, through larval propagation, they can select or randomly mix gametes, producing genetically unique individuals that might be better able to withstand ocean warming. These new, genetically unique corals, if vigorous, can then be grown in large numbers by fragmentation.

The planula are either kept in the lab or transferred back to the ocean in special rearing pools, called Coral Rearing In Situ Basins (CRIBs). These floating CRIBs allow seawater to flow through the enclosure while keeping the larvae contained as they grow.

After few days to a few weeks, depending on the species, the planula start scouting the bottom for a home. They are very picky. In the CRIBs, RRFB places thousands of substrates, called seeding units, designed for easy outplanting and to provide the planula an attractive place to settle. Once the planula have firmly attached onto the seeding units, they are outplanted to degraded reef areas. Now they must face the reef life on their own, however RRFB monitors their health.

This essential and ongoing effort is led by marine biologist, Francesca Virdis, her assistant and marine biologist, Sanne Tuijten, and reef restoration technician, Ernst Noyons. Together, they rely on the dedication of dozens of volunteers, divers from all around the world, of all ages and walks of life, who want to give back a bit of the joy they’ve experienced from the reef. They also welcome interns interested in nonprofit marine conservation with a focus on the restoration of tropical coral reef systems and are always looking for more volunteers, donations, and supplies.

While we need to reduce the amount of CO2 in the atmosphere that is causing increased bleaching and acidification over the long term, there are simple, more immediate ways to help—and the results have been phenomenal! These restoration efforts offer tangible proof that we can reverse the damage and save not only the reefs and the myriad life that they contain, but ourselves and this little blue marble that is our home.

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