What coral reefs need
We know what is putting the world’s coral reefs in peril today, but what ideal conditions created them in the first place and how can they be maintained?
Discover the origins of colourful coral reefs and the conditions required to sustain them for the future
Aragged crescent of land ringed by the sharp peaks of relatively young volcanoes encloses Kimbe Bay on the north coast of the island of New Britain in the southern Pacific. Part of Papua New Guinea, this island, and in particular that bay, is known by marine scientists for its astonishing biodiversity.
Within the shelter of a geologically turbulent land mass, awe-inspiring coral reefs teem with oceanic life. This is thought to be the evolutionary birthplace of the world’s coral reefs. What gave rise to this theory is the particular set of topographical features around the bay and the actions of the area’s ocean currents.
New Britain lies north of the Solomon Sea and cups the Bismarck Sea. South of the island, and parallel to it, is the Bougainville Trench, one of the deepest in the region, dropping to more than 9,000m (30,000ft) – deeper than Everest is high. The trench is a long narrow depression in the seabed, marking where a plate in the Earth’s crust is sliding under another, like a wrinkle in a piece of cloth.
Perfect conditions
Trenches gather detritus containing organic matter, nitrogen and phosphorous. Powerful ocean currents stir up that nutrient-rich sediment and carry it to shallower areas. In New Britain and Kimbe Bay, the nutrients from the Bougainville Trench are carried upwards by the South Equatorial Current and northwards around the island.
As the current follows the land’s contours, it swirls around the shallow shelf that forms Kimbe Bay and nutrients gather there at a time of year when the waters are at the optimum temperature to promote life. Blown by the trade winds from across the Pacific, the current is also oxygen-rich. Together, these conditions promote coral growth. And with coral comes a plethora
of marine life, from the microscopic to the mega. Surveys in Kimbe have recorded 400 types of coral, 860 varieties of fish and at least 10 cetacean species.
This abundance of life was first drawn to the attention of the scientific community in the 1970s, when Australians Max and Cecilie Benjamin, working as agricultural officers for New Britain Palm Oil Development and the Papua New Guinea Department of Agriculture alternately, began diving in Kimbe Bay. As Cecilie later said: “The Bay was our undiscovered universe. It is now recognised that the greatest marine diversification of coral on Earth occurs in the region bordered by the Solomon Islands, Papua New Guinea, East Indonesia and the southern Philippines. This is the so-named Coral Triangle, home to 75 per cent of the world’s coral species... The Bismarck Sea, where Kimbe Bay is situated, is almost central to this triangle.” So far, Kimbe Bay’s corals have largely escaped the effects of sea temperature rises. Thanks again to the power of the Pacific’s currents, the results of El Niño episodes rising in South American waters have been deflected south before reaching New Britain – bad for the Great Barrier Reef, but good for Kimbe. What will happen with the general rise in ocean temperatures, only time will tell, but for now Kimbe Bay has been touched only lightly. However, another humangenerated threat has arisen, and engendered an all-round awareness of the fragility of the reefs. New Britain has the highest population growth in Papua New Guinea – the number of people there is predicted to double in the next 25 to 30 years. A high birth-rate has been coupled with the availability of employment and inclusion in the industry as smallholders on Land Settlement Schemes and Customary Village Oil Palm holdings in oil palm production. This has brought people to the area who seek benefits from the industryprovided work, housing, and schools.
Fishing and farming
To augment their home-grown food, local village people fish the coastal adjacent reef. Subsistence fishing is not the problem, though; it’s the way the fishing is carried out that has an impact. Locals have been accustomed to using the pounded-up root of Derris elliptica vine, that contains rotenone, a powerful natural insecticide. Thrown into
Surveys of Kimbe Bay have recorded 400 types of coral, 860 varieties of fish and at least 10 cetacean species.
the water, the root stuns the fish and causes them to rise to the surface where they are easy to catch. Unfortunately, the rotenone then sinks onto the reef and kills the coral.
Additionally, there has been a historic impact of oil palm farming in the area, that is now being addressed. In New Britain, there is a commitment from the industry to environmentally and socially responsible development that prevents agricultural chemical run-off and preserves the carbon sink areas threatened with deforestation. This is something that Max Benjamin, as a trained agriculturalist, is passionate about. “Palm oil is a many times more efficient and sustainable way of producing vegetable oil than any other plant form,” he says. “One hectare can supply several yields a year.” Max feels that unscrupulous palm oil production in other countries has tarred all palm oil production with the same brush, and perceptions of the business as a whole have therefore suffered.
Setting up ‘buffer zones’ – areas of vegetation separating oil palm plantations from the coast – helps to absorb chemicalrun off into coral reefs. A key requirement for extracting sustainable palm oil that can be exported to Europe, it’s a principle that producers here have embraced.
Recognising that education was the way forward in persuading fishermen to use more reef-friendly methods, the Benjamins were instrumental in the setting up of the Mahonia Na Dari (Guardian of the Sea) institute in 1997, an NGO formed to provide a Marine Environment Education Program for the youth of West New Britain Province. It formed close links with James Cook University in Australia and in 2018 served as a base for marine researchers from a total of six universities.
Planting the seed
Peter Miller is the program director and Somei Jonda the education officer at Mahonia Na Dari, and both have been involved in producing an education guide, which has been distributed to a network of teachers to encourage future generations in marine environment conservation.
“As part of our outreach programme, Somei takes out a team of local dialect speakers, called marine educators, to the more remote areas of the island,” Peter says. “He stays in the districts for about two weeks and takes in as many schools as he can. In this way, he has reached some 11,000 kids annually. Last year the theme was Climate Change and Adaptations and we have a mangrove rehabilitation project that was perfect for the adaptations part.”
Mangroves are important for coastal protection as they stop potentially reefharming sediments flowing off the land. They also provide a nursery for reef fish. A WWF study showed that there are 25 per cent more of some fish species found on reefs close to mangrove areas.
“Somei teaches children how to identify the hardier types of mangrove seeds, how to grow and plant them out,” Peter says. In fact, plans are underway for 10,000 trees to be planted by local schoolchildren. Work began last November, when Mahonia Na Dari arranged a day when 96 students from six local schools planted 1,022 seedlings.
There are more intensive courses at Mahonia HQ too, in conservation theory and field work, for five of the island’s technical and high schools, and according to Peter the enthusiasm of the students to learn is abundantly obvious. “The first teaching session I did here, I knew within an hour there were 20 conservationists who hadn’t been there an hour before.”
Ripple effect
“When we go on the outreach programme we also talk to people about how they can manage their resources better,” says Somei. “We can’t enforce a change in behaviour; the reefs are their resource. All we can do is educate them. People here eat reef fish a lot, so we tell them about the bad effects of derris root and encourage them to use hook and line instead.”
“We give them ideas from places like the Solomon Islands, where they use size discrimination for fishing – if they are under a certain length they’re too young and you put them back, and if they are over a certain length you also return them because they are the breeding stock.”
What the future holds if ocean temperatures continue to rise is unknown, but current efforts are helping to preserve the health of Kimbe Bay’s reefs, so the birthplace of coral is doing okay for now.