World Wildlife Fund

WWF marine conservation biologist Dr. Helen Fox is your underwater guide through the remarkably varied and valuable world of coral reefs.

Every few years, news surfaces telling us of the amazing discovery of some underwater city lost into the world’s seas thousands of years ago by the action of earthquakes, tsunamis or other natural disasters. But long before people began building these and other structures for human communities, nature was at work building coral reefs – equally complex environments characterized by well-established structures and intricate interdependencies among inhabitants.

These natural cities under the sea are shallow ocean habitats with a wild profusion of large, stone-like corals and an extensive community of species growing or moving among them. The profile of a coral reef stretches from shore to sea in different structures, all created from growths of calcium carbonate that build upwards in the warm lightfilled waters of the tropics.

The Richest “Cities” in the World Coral reefs are remarkably rich in diversity, with a wider range of species than any other ecosystem on the planet – tropical rain forests included. Globally they cover a collective area of some 110,000 square miles, about the size of Nevada. And they are also incredibly valuable, providing us with food, medicines and livelihoods, and protecting shorelines around the world.

There are thousands of different species of fish darting around the reefs, yet these fish and other vertebrates make up only about 7 percent of the animal species. The spectacular invertebrate biodiversity makes up the other 93 percent, from giant corals to tiny, colorful nudibranchs or sea slugs. Much of this biodiversity remains unexplored, with estimates of literally millions of undiscovered marine species. This biological wealth is not only beautiful to behold, it also holds within it substances that may be the source of new medicines for bacterial infections, viruses, arthritis and cancer.

I have a childhood memory of snorkeling on a coral reef in Puerto Rico, floating in warm water, watching waving sea fans and soft corals. As an adult my first time snorkeling in the water in Bunaken National Park, Indonesia, on a WWF site visit, just about knocked my dive booties off. I was overwhelmed by the profusion of corals and fish and other plants and animals making their living on the reef. I have logged nearly 1,000 dives doing research on reefs, and almost every time I have seen something worth a closer look.

Thousands of species of fish live in the waters around coral reefs, from the tiny 3-inch damselfish to the parrotfish, to the shimmering schoolmaster napper, which is among the food fish popular in the U.S.
© Brandon D. Cole

Worth Their Weight in Gold Coral reefs cover only 0.2 percent of the ocean floor yet contain about 25 percent of all marine species. Millions of people depend on the coastal fisheries and tourism enterprises made possible by these highly productive ecosystems. Coastal tourism – driven significantly by coral reefs – is worth about US$385 billion annually. Coral reefs also play an essential role in maintaining shorelines, buffering them from the full power of ocean waves, preventing erosion, protecting wetlands along our coasts, and harboring ports and the economic activity they provide to local communities. Globally, half a billion people are estimated to live within 65 miles of a coral reef and benefit from its production and protection.

The Backbone of Coral Reefs There are more than 2,000 species of corals across the four main categories of coral types: hydrocorals (which include the stinging fire corals), black corals, octocorals (so-called because of the eight tentacles around each polyp mouth), and the scleractinian, or hard/stony corals. The stony corals are the ones that build coral reefs, structures – like cities under the sea – that provide habitat for thousands of species in communities of almost unimaginable numbers.

The hard corals themselves can contain anywhere from several hundred to hundreds of thousands of individual animals, or polyps, living together in colonies. The coral harvests the energy of the sun through a symbiotic relationship with tiny photosynthetic algae, or zooxanthellae, that live in its tissues. These algae provide the polyps with oxygen and the building blocks they need to make proteins, fats and carbohydrates to supplement their diet of tiny floating animals known as zooplankton; the algae also give the coral its frequently spectacular color.

As a coral animal grows, it deposits layers of calcium carbonate, a limestone-like substance, in a cup shape around itself. This layering – which looks remarkably like a human skeleton – becomes the structure of the reef. Although an individual coral animal is small, the collective power of so many of them growing together in colonies is astonishing: The world’s largest coral reef system, the Great Barrier Reef off Queensland, Australia, is visible from outer space. The second largest, the Belize Barrier Reef, stretches 90 miles through the Mesoamerican Reef, from southern Quintana Roo, Mexico, all along the coast of Belize and down to the Bay Islands of Honduras.

The Science of Coral Reef Conservation WWF is working on many fronts to better understand and conserve coral reefs – from using satellite imagery and geographic information systems (GIS) technology to map where reefs are, to working with local partners and communities to restore mangroves so they can protect the coastline and coral reefs from climate change.

A core strategy of coral reef conservation is developing effectively managed marine protected areas (MPAs) and connecting them in viable networks. Today, less than 1 percent of the world’s oceans are protected. While the majority of these protected waters are in the tropics, it’s not enough – and not every MPA is producing lasting results. At WWF, we’re committed to building up the global system of MPAs and to creating networks among them that further their long-term viability.

We use a variety of scientific disciplines to learn how to design MPAs so that they are a “win” for both biodiversity and communities. If an MPA is a biological success at the expense of local people, or is well-liked by communities but insufficient for biodiversity protection, it’s not an effective or sustainable one.

WWF is beginning an interdisciplinary research initiative to examine the links between MPAs, biodiversity conservation and poverty alleviation. Our work focuses on three areas: measuring the conservation and poverty impacts of these protected places, explaining why some provide benefits to both people and marine biodiversity while others do not, and identifying the key elements of a fully successful marine protected area.

Not Just a Problem of Overfishing I was on-site in the Coral Triangle, surveying a lagoon in the Solomon Islands. This is a place where logging, not overfishing, is the biggest threat to the reefs, and I saw the impact firsthand. Every time it rained, the water turned to soup as sediment ran off the deforested land, blocking the sunlight and smothering the corals.

WWF experts have done similar research in and around the South Pacific Ocean island of American Samoa, where again overfishing is not the only problem. On this tiny island of 77 square miles – about the size of Washington, D.C. – there are more than 900 piggeries and close to 8,000 pigs. About 80 percent of the piggeries discharge waste directly into streams; this agricultural runoff ends up in the ocean. WWF has documented the positive relationship between water quality and the ability of coral reefs to adapt to climate change: the higher the water quality, the greater the ability. This is strong evidence to support better management of watersheds and agricultural activities.

The Greatest Threat of All: Climate Change Already, climate change is affecting our ocean environments and seriously weakening coral reefs. Elkhorn and staghorn corals are now listed as threatened under the U.S. Endangered Species Act for their whole Caribbean range, which includes the Mesoamerican Reef.

There has never been greater urgency to protect the world’s coral from the impacts of climate change. WWF has never been working harder to do so. We’re teaming our biologists, social scientists, climate scientists, field staff, and policy and business experts to tackle the causes of climate change globally, while we’re on the ground around the world strengthening ecosystem resistance (the ability to withstand change) and resilience (the ability to recover from change).

Across the Asia-Pacific region, we’re leading a program that engages local stakeholders and decision makers in developing, testing and implementing plans to increase coral reef resilience to climate change. WWF supports collaboration among the governments of major reef countries to enhance the management and networking of marine protected areas.

In Coastal East Africa we are building up coastal resilience by restoring tropical mangroves. Their underwater root systems protect shorelines by buffering against storm surges and rising tides. Healthy mangroves also protect reefs from pesticide and sediment runoff from the land.

The Greatest Place of All: The Coral Triangle According to the Status of Coral Reefs of the World: 2004, a major research report supported by WWF, 70 percent of the world’s coral reefs are threatened or destroyed, with 20 percent of those damaged beyond repair. This problem is big; the solution must be even bigger.

That’s why WWF has launched our new Network Initiative for the Coral Triangle, the richly biodiverse waters off the coasts of Indonesia, Malaysia, the Philippines, the Solomon Islands, Papua New Guinea and Timor Leste. My colleague Kate Newman has spent the last year spearheading a campaign to gain international support for this remarkable place, which contains 75 percent of all known coral species. Initial successes have included helping to bring together the six Coral Triangle countries on a joint conservation initiative. Our efforts will protect the Coral Triangle’s biological diversity and ensure the economic viability of the ecosystem.