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Biodiversity Helps Coral Reefs Thrive and Could Be Used Strategically to Save Them

Insights + Opinion
A healthy coral reef at Swains Island, American Samoa. NOAA / NMFS / PIFSC / CRED, Oceanography Team / CC BY 2.0

By Cody Clements

Coral reefs are home to so many species that they often are called "the rainforests of the seas." Today they face a daunting range of threats, including ocean warming and acidification, overfishing and pollution. Worldwide, more than one-third of all coral species are at risk of extinction.


I am one of many scientists who are studying corals to find ways of helping them survive and recover. As a recent report from the National Academies of Science, Engineering and Medicine shows, researchers are exploring many different strategies. Some, such as managed breeding to make corals more tolerant of stresses, are already being developed at small scales. Others, such as moving corals to colonize new areas, have not been tested yet.

My own work examines whether greater diversity of coral species on reefs can help corals survive and thrive. In a study published earlier this year, my colleague Mark Hay and I found evidence that the answer is yes. This finding could help to inform broader strategies for making coral reefs more resilient in altered oceans.

In Nature, More Is Better

Are ecosystems healthier if they contain many species than if they harbor only a few? This is a central question in ecology. Generally, scientists have found that ecosystems with more diverse foundation species – those that define a system and are inseparable from it, such as trees in a forest – tend to be healthier and function better.

Until recently, no one had applied this test to coral reefs. But we do know that healthy coral reefs are diverse, structurally complex ecosystems dominated by corals. In contrast, reefs that have been damaged by stresses such as coral bleaching events tend to become simplified, less diverse landscapes, often dominated by seaweeds.

For our study we chose a reef area on the southwestern coast of Fiji's main island, Viti Levu, in the South Pacific. Many reefs along this coast have been heavily degraded by overfishing and other human-related activities, reducing coral cover and allowing seaweeds to dominate.

There are hundreds of coral species across the Pacific, but at smaller scales, we found just five species or fewer during preliminary surveys conducted on the degraded reef at our site. Since these conditions mirror what is happening to many reefs worldwide, we saw it as an ideal place to test whether coral diversity matters for the "new normal" that we expect to see on reefs of the future.

Underwater Gardens

Our team created 48 concrete plots on the sea floor of the degraded reef, which served as the bases for experimental coral gardens. We created single-species gardens that each contained one of three coral species – Pocillopora damicornis, commonly known as cauliflower coral; Porites cylindrica, also known as yellow finger coral; and Acropora millepora, one of a number species known as staghorn corals. We also planted mixed gardens containing all three species.

We chose these corals because they are common to reefs across the Pacific and are representative of different coral families that have shown varying responses to a variety of harmful disturbances. In all, each garden contained 18 coral individuals, for a total of 864 corals.

To assess each coral's performance as it grew, we needed to remove them from their plots periodically. So we cut off the tops of hundreds of soda bottles and planted an individual coral in the upside-down neck of each bottle with epoxy putty. We embedded the bottle caps into our concrete slabs so that we could easily unscrew each bottle neck to examine the coral it held, then screw it back into its base. Over 16 months we weighed the corals and tracked other measures of their well-being, including tissue death and colonization of each garden by harmful seaweeds.

Experimental coral gardens on a degraded reef in Fiji. Gardens with a mix of coral species performed better than gardens containing only one species.

Cody Clements / CC BY-ND

We consistently found that corals grown in mixed-species gardens performed better than those in single-species plots. Within four months, coral growth in the mixed-species gardens was even exceeding the best-performing single-species gardens. This suggests that different species may benefit each other in yet unknown ways, at least during early stages of a coral community's development.

Examples of single- and mixed-species coral gardens through time during our 16-month experiment. At four months, mixed-species gardens were outperforming single-species gardens in multiple ways – growing faster on average than even the best performing single-species gardens (Acropora millepora). By 16 months, growth was comparable between mixed-species and Acropora gardens, but aggregate performance of single-species gardens continued to lag behind their mix-species counterparts.

Clements and Hay, 2019 / CC BY-ND

Why Is More Better?

The next question is what drove the effects that we observed. We hope to investigate a number of leads in future experiments. For example, farmers commonly observe that planting a diverse mix of crops helps to reduce the spread of infectious diseases among individuals. Could the same be true for coral reefs?

Our initial findings offer both concern and hope for the future of coral reefs. If diversity is integral to coral well-being, then continued species loss could dramatically alter these ecosystems in ways that lead to further reef decline. How many parts can be removed from the "ecosystem engine" before it breaks down?

That said, many of the strategies in the National Academies report involve using biodiversity – both at the genetic and species level – to enhance coral reef resilience. Examples include cross-breeding corals between populations; altering coral genes to give them new functions, such as higher heat tolerance; and moving stress-tolerant corals or coral genes to new locations.

Promising advances in technology, such as mapping coral reefs from the air, may also help researchers assess coral health and determine which species they contain. This baseline information may help better inform management and restoration efforts.

Corals are in trouble, but they aren't down for the count yet. Perhaps harnessing the power of their remaining biodiversity can help give them a fighting chance.

Cody Clements is a postdoctoral fellow at the Georgia Institute of Technology.
Disclosure statement: Cody Clements receives funding from the National Science Foundation, the National Institutes of Health, the National Geographic Society, and the Teasley Endowment to the Georgia Institute of Technology.

Reposted with permission from our media associate The Conversation.

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Ola Elvestrun, Norway's environment minister, announced Thursday that it is freezing its contributions to the Amazon Fund, and will no longer be transferring €300 million ($33.2 million) to Brazil. In a press release, the Norwegian embassy in Brazil stated:

Given the present circumstances, Norway does not have either the legal or the technical basis for making its annual contribution to the Amazon Fund.

Brazilian President Jair Bolsonaro reacted with sarcasm to Norway's decision, which had been widely expected. After an official event, he commented: "Isn't Norway the country that kills whales at the North Pole? Doesn't it also produce oil? It has no basis for telling us what to do. It should give the money to Angela Merkel [the German Chancellor] to reforest Germany."

According to its website, the Amazon Fund is a "REDD+ mechanism created to raise donations for non-reimbursable investments in efforts to prevent, monitor and combat deforestation, as well as to promote the preservation and sustainable use in the Brazilian Amazon." The bulk of funding comes from Norway and Germany.

The annual transfer of funds from developed world donors to the Amazon Fund depends on a report from the Fund's technical committee. This committee meets after the National Institute of Space Research, which gathers official Amazon deforestation data, publishes its annual report with the definitive figures for deforestation in the previous year.

But this year the Amazon Fund's technical committee, along with its steering committee, COFA, were abolished by the Bolsonaro government on 11 April as part of a sweeping move to dissolve some 600 bodies, most of which had NGO involvement. The Bolsonaro government views NGO work in Brazil as a conspiracy to undermine Brazil's sovereignty.

The Brazilian government then demanded far-reaching changes in the way the fund is managed, as documented in a previous article. As a result, the Amazon Fund's technical committee has been unable to meet; Norway says it therefore cannot continue making donations without a favorable report from the committee.

Archer Daniels Midland soy silos in Mato Grosso along the BR-163 highway, where Amazon rainforest has largely been replaced by soy destined for the EU, UK, China and other international markets.

Thaís Borges.

An Uncertain Future

The Amazon Fund was announced during the 2007 United Nations Climate Change Conference in Bali, during a period when environmentalists were alarmed at the rocketing rate of deforestation in the Brazilian Amazon. It was created as a way of encouraging Brazil to continue bringing down the rate of forest conversion to pastures and croplands.

Government agencies, such as IBAMA, Brazil's environmental agency, and NGOs shared Amazon Fund donations. IBAMA used the money primarily to enforce deforestation laws, while the NGOs oversaw projects to support sustainable communities and livelihoods in the Amazon.

There has been some controversy as to whether the Fund has actually achieved its goals: in the three years before the deal, the rate of deforestation fell dramatically but, after money from the Fund started pouring into the Amazon, the rate remained fairly stationary until 2014, when it began to rise once again. But, in general, the international donors have been pleased with the Fund's performance, and until the Bolsonaro government came to office, the program was expected to continue indefinitely.

Norway has been the main donor (94 percent) to the Amazon Fund, followed by Germany (5 percent), and Brazil's state-owned oil company, Petrobrás (1 percent). Over the past 11 years, the Norwegians have made, by far, the biggest contribution: R$3.2 billion ($855 million) out of the total of R$3.4 billion ($903 million).

Up till now the Fund has approved 103 projects, with the dispersal of R$1.8 billion ($478 million). These projects will not be affected by Norway's funding freeze because the donors have already provided the funding and the Brazilian Development Bank is contractually obliged to disburse the money until the end of the projects. But there are another 54 projects, currently being analyzed, whose future is far less secure.

One of the projects left stranded by the dissolution of the Fund's committees is Projeto Frutificar, which should be a three-year project, with a budget of R$29 million ($7.3 million), for the production of açai and cacao by 1,000 small-scale farmers in the states of Amapá and Pará. The project was drawn up by the Brazilian NGO IPAM (Institute of Environmental research in Amazonia).

Paulo Moutinho, an IPAM researcher, told Globo newspaper: "Our program was ready to go when the [Brazilian] government asked for changes in the Fund. It's now stuck in the BNDES. Without funding from Norway, we don't know what will happen to it."

Norway is not the only European nation to be reconsidering the way it funds environmental projects in Brazil. Germany has many environmental projects in the Latin American country, apart from its small contribution to the Amazon Fund, and is deeply concerned about the way the rate of deforestation has been soaring this year.

The German environment ministry told Mongabay that its minister, Svenja Schulze, had decided to put financial support for forest and biodiversity projects in Brazil on hold, with €35 million ($39 million) for various projects now frozen.

The ministry explained why: "The Brazilian government's policy in the Amazon raises doubts whether a consistent reduction in deforestation rates is still being pursued. Only when clarity is restored, can project collaboration be continued."

Bauxite mines in Paragominas, Brazil. The Bolsonaro administration is urging new laws that would allow large-scale mining within Brazil's indigenous reserves.

Hydro / Halvor Molland / Flickr

Alternative Amazon Funding

Although there will certainly be disruption in the short-term as a result of the paralysis in the Amazon Fund, the governors of Brazil's Amazon states, which rely on international funding for their environmental projects, are already scrambling to create alternative channels.

In a press release issued yesterday Helder Barbalho, the governor of Pará, the state with the highest number of projects financed by the Fund, said that he will do all he can to maintain and increase his state partnership with Norway.

Barbalho had announced earlier that his state would be receiving €12.5 million ($11.1 million) to run deforestation monitoring centers in five regions of Pará. Barbalho said: "The state governments' monitoring systems are recording a high level of deforestation in Pará, as in the other Amazon states. The money will be made available to those who want to help [the Pará government reduce deforestation] without this being seen as international intervention."

Amazonas state has funding partnerships with Germany and is negotiating deals with France. "I am talking with countries, mainly European, that are interested in investing in projects in the Amazon," said Amazonas governor Wilson Miranda Lima. "It is important to look at Amazônia, not only from the point of view of conservation, but also — and this is even more important — from the point of view of its citizens. It's impossible to preserve Amazônia if its inhabitants are poor."

Signing of the EU-Mercusor Latin American trading agreement earlier this year. The pact still needs to be ratified.

Council of Hemispheric Affairs

Looming International Difficulties

The Bolsonaro government's perceived reluctance to take effective measures to curb deforestation may in the longer-term lead to a far more serious problem than the paralysis of the Amazon Fund.

In June, the European Union and Mercosur, the South American trade bloc, reached an agreement to create the largest trading bloc in the world. If all goes ahead as planned, the pact would account for a quarter of the world's economy, involving 780 million people, and remove import tariffs on 90 percent of the goods traded between the two blocs. The Brazilian government has predicted that the deal will lead to an increase of almost $100 billion in Brazilian exports, particularly agricultural products, by 2035.

But the huge surge this year in Amazon deforestation is leading some European countries to think twice about ratifying the deal. In an interview with Mongabay, the German environment ministry made it very clear that Germany is very worried about events in the Amazon: "We are deeply concerned given the pace of destruction in Brazil … The Amazon Forest is vital for the atmospheric circulation and considered as one of the tipping points of the climate system."

The ministry stated that, for the trade deal to go ahead, Brazil must carry out its commitment under the Paris Climate agreement to reduce its greenhouse gas emissions by 43 percent below the 2005 level by 2030. The German environment ministry said: If the trade deal is to go ahead, "It is necessary that Brazil is effectively implementing its climate change objectives adopted under the [Paris] Agreement. It is precisely this commitment that is expressly confirmed in the text of the EU-Mercosur Free Trade Agreement."

Blairo Maggi, Brazil agriculture minister under the Temer administration, and a major shareholder in Amaggi, the largest Brazilian-owned commodities trading company, has said very little in public since Bolsonaro came to power; he's been "in a voluntary retreat," as he puts it. But Maggi is so concerned about the damage Bolsonaro's off the cuff remarks and policies are doing to international relationships he decided to speak out earlier this week.

Former Brazil Agriculture Minister Blairo Maggi, who has broken a self-imposed silence to criticize the Bolsonaro government, saying that its rhetoric and policies could threaten Brazil's international commodities trade.

Senado Federal / Visualhunt / CC BY

Maggi, a ruralista who strongly supports agribusiness, told the newspaper, Valor Econômico, that, even if the European Union doesn't get to the point of tearing up a deal that has taken 20 years to negotiate, there could be long delays. "These environmental confusions could create a situation in which the EU says that Brazil isn't sticking to the rules." Maggi speculated. "France doesn't want the deal and perhaps it is taking advantage of the situation to tear it up. Or the deal could take much longer to ratify — three, five years."

Such a delay could have severe repercussions for Brazil's struggling economy which relies heavily on its commodities trade with the EU. Analysists say that Bolsonaro's fears over such an outcome could be one reason for his recently announced October meeting with Chinese President Xi Jinping, another key trading partner.

Maggi is worried about another, even more alarming, potential consequence of Bolsonaro's failure to stem illegal deforestation — Brazil could be hit by a boycott by its foreign customers. "I don't buy this idea that the world needs Brazil … We are only a player and, worse still, replaceable." Maggi warns, "As an exporter, I'm telling you: things are getting very difficult. Brazil has been saying for years that it is possible to produce and preserve, but with this [Bolsonaro administration] rhetoric, we are going back to square one … We could find markets closed to us."

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