Tag Archives: Great Barrier Reef

A Resurrection Story: the Great Barrier Reef

Heron Island, a coral cay in the southern Great Barrier Reef. Image from wikipedia

Great Barrier Reef, which runs for 2,300km along the coast of Queensland, is one of the icons of environmentalism. Conservationists constantly worry that human activity, particularly greenhouse-gas-induced global warming, will harm or even destroy it….Reef-forming corals prefer shallow water so, as the world’s sea levels have yo-yoed during the Ice Ages, the barrier reef has come and gone. The details of this have just been revealed in a paper published in Nature Geoscience by Jody Webster of the University of Sydney and her colleagues…. They discovered that it has died and then been reborn five times during the past 30,000 years. Two early reefs were destroyed by exposure as sea levels fell. Three more recent ones were overwhelmed by water too deep for them to live in, and also smothered by sediment from the mainland. The current reef is therefore the sixth of the period.

The barrier reef’s ability to resurrect itself is encouraging. But whether it could rise from the dead a sixth time is moot. The threat now is different. It is called bleaching and involves the tiny animals, known as polyps, which are the living part of a reef, ejecting their symbiotic algae. These algae provide much of a polyp’s food, but also generate toxins if the temperature gets too high, in which case the polyp throws them out. That causes the coral to lose its colour.  Polyps can tolerate occasional bleaching, but if it goes on too long, then they die. In the short term, therefore, global warming really does look a serious threat to the reef. It would, no doubt, return if and when the sea temperature dropped again. But when that would be, who knows?

Excerpts from Conservation: A Great Survivor, Economist, June 2, 2018, at 78

Engineering Coral Reefs

Coral Reef, image from wikipedia

In the past half-century, though, these beautiful, biodiverse structures have been put under pressure by human activity. About a quarter of all coral cover has died. The reefs that are in worst shape are those off the most crowded beaches. “People don’t leave enough time for their sun cream to soak in, so it gets in the water,” says one deckhand with Eo Wai’anae Tours, which organises boat trips off Oahu. More damage is caused by fertiliser-rich run-off from farms, leading to algal blooms which block light the corals need. Fishing near reefs cuts the number of herbivorous fish, allowing vegetation to grow out of control. Some fishing methods are particularly harmful: for example, blast fishermen in Colombia, Tanzania and elsewhere use dynamite to stun and kill fish without regard to the harm done to nearby reefs…In the South China Seaisland-building and fishing for giant clams are crushing some reefs beyond the possibility of recovery (seearticle)….

Tourism generated by the Great Barrier Reef is worth about $4.6 billion annually to nearby Queensland alone. Australian bigwigs bent over backwards last year to keep the UN from listing the reef, a World Heritage Site, as “in danger”. Estimates suggest that the economic value of Martinique and Saint Lucia’s corals comes to $50,000 per square km each year, thanks largely to tourism. But overdevelopment threatens the reefs the visitors come to gawp at. Sediment from construction clouds waters, burying corals and blocking the light they need. Hotels close to the shore may be convenient for tourists, but the process of building them can kill the reefs that snorkellers like to swim over…The three countries with the largest numbers of people who fish on reefs are all in the coral-triangle region: Indonesia, Papua New Guinea and the Philippines. In Indonesia and in the Philippines, up to 1m people’s livelihoods depend on reefs.

Averting a tragedy of the commons means agreeing which activities should be restricted and enforcing the rules. For coral reefs—and other biodiverse marine environments—the usual approach is to give ecologically sensitive areas special status under local or regional laws. In such “marine protected areas” (MPAs), activities that are deemed harmful, such as fishing, drilling and mining, can then be restricted or banned, with penalties for rule-breakers.

The Aichi targets, agreed in 2010 under the UN Convention on Biological Diversity, seek to reduce “anthropogenic pressures” on coral reefs to “maintain their integrity and function”. The aim is to have at least 17% of inland water and 10% of coastal and marine areas under conservation by 2020. Most countries have signed up. But the targets are far from being met. Less than 3% of the ocean’s surface is within an MPA.

The most urgent action is needed close to shore. The nearer humans are to reefs, the worse their effect on the fragile ecosystems. A global register of fishing vessels, long under discussion, would also help identify wrongdoers. And beefing up the UN law of the sea could inspire further action. Decades old, it has little to say about biodiversity.

But simply declaring an area protected does not make it so. In 2009 George Bush junior, then president of America, established three national marine monuments in the Pacific, including nearly 518,000 square km of coral islands and surrounding areas. Their remoteness makes it hard to stop vessels entering illegally; Hawaii’s coastguard is already stretched.

Satellites are sometimes used to police MPAs, but they pass over infrequently. In the future, sailing robots could play a larger role. America’s National Oceanic and Atmospheric Administration (NOAA) has been working with a private firm, Saildrone, on hardy models equipped with carbon-fibre fins. They cost less than $500,000 each and can roam remote ocean regions for months, making them far cheaper than manned boats.

Such drones could photograph rogue fishing vessels, obtaining hard-to-gather evidence for any criminal proceedings. And they could carry out other useful work at the same time, such as monitoring ocean temperature and acidity or tracking tagged members of endangered species. Saildrone plans to provide its robots as a service, so that universities and other cash-strapped organisations do not have to buy one outright…

Even if the right policies are adopted to keep corals healthy in the immediate future, longer-term threats loom. Neither oceanic warming nor acidification can be kept out by an MPA. And both may be happening too fast for corals to adapt, especially as recent global climate deals will not slow them much. Back slaps and handshakes accompanied the inclusion of an aim to limit global warming to just 1.5°C above pre-industrial levels in the Paris Agreement last year. But only an incorrigible optimist would bet on that aim being achieved.

So researchers are turning their attention to ways to help corals cope. Their global diversity, scientists hope, may hold the key. The same coral will grow differently under different conditions: corals of the western Pacific near Indonesia, for example, can withstand higher temperatures than the same species in the eastern Pacific near Hawaii….The characteristics that help some reefs survive unusual conditions could allow others to endure climate change. But tough corals from one place cannot simply be transplanted to another. So a team at the Hawaii Institute of Marine Biology is in the early stages of engineering reef ecosystems, with $4m from the Paul G. Allen Foundation, a charity set up by Bill Gates’s former business partner.

Organisms respond to environmental changes through both genetic processes (adaptation) and non-genetic ones (acclimatisation). With corals, the nature of their symbiotic relationships can also alter. So selectively breeding and conditioning them, and investigating whether certain types of algae confer resistance to heat or acidity, could create hardier varieties faster than they would develop naturally.

These could then be used to repopulate ravaged reefs—once more is known about how and where to transplant them. “We’re assisting evolution,” explains Ruth Gates, who leads the research.

Marine conservation: Rejuvenating reefs, Economist, Feb. 13, at 57

How to Build Climate Resilience in Ecosystems

Great Barrier Reef, Australia

Some ecosystems show little response [to climate change] until a threshold or tipping point is reached where even a small perturbation may trigger collapse into a state from which  recovery is difficult .  ….[S}uch collapse may be altered by conditions that can be managed locally…. [This] provides  potential opportunities for pro-active management.…[C]rises in iconic UNESCO World Heritage sites illustrate that such stewardship is at risk of failing. The term “safe operating space” frames the  problem of managing our planet in terms of staying within acceptable levels or “boundaries” for global stressors [Such as climate change]….

Obviously, local interventions are no panacea for the threats of climatic change. For example, melting of arctic sea ice with its far-reaching ecological consequences cannot be arrested by local management. However, ways of building climate resilience are emerging for a variety of ecosystems, ranging from control of local sources of ocean acidification  to management of grazing pressure on dry ecosystems,World Heritage Areas.

The Doñana wetlands in southern Spain provide the most important wintering site for waterfowl in Europe. They contain the largest temporary pond complex in Europe, with a diversity of amphibians and invertebrates. Despite the site’s protected status, the marshes are threatened by eutrophication due to pollution and reduced flow of incoming streams, promoting toxic cyanobacterial blooms and dominance by invasive floating plants that create anoxic conditions in the water. In addition, groundwater extraction for strawberry culture and beach tourism also has major impacts.  Little has been done to control these local stressors, leaving Doñana unnecessarily vulnerable to climate change. UNESCO has just rated this World Heritage Site as under ‘very high threat’.

The Great Barrier Reef is the largest coral system in the world. In response to multiple threats, fishing has been prohibited since 2004 over 33% of the Great Barrier Reef Marine Park, and efforts have begun to reduce runoff of nutrients, pesticides, herbicides and sediments from land. However, these interventions may be too little, too late. Approximately half of the coral cover has been lost in recent decades, and the outlook is “poor, and declining” with climate change, coastal development and dredging as major future threats. The World Heritage Committee has warned that in the absence of a solid long-term plan, it would consider listing the reef as “in danger” in 2015.

More available online Creating a Safe Operating Space for Iconic Ecosystems By M. Scheffer et al, 2015