Tag Archives: climate change coral reefs

Oceans Restored: the 2050 Deadline

A study published in Nature on April 2, 2020 claims that marine ecosystems could recover in just 30 years because of the growing success of conservation efforts and the ocean’s remarkable resilience. Some of these conservation efforts include the increase in Marine Protected Areas (MPAs) from less than 1 percent in 2000 to almost 8 percent today and the restoration of key habitats such as seagrass beds and mangroves

One great success is the restoration of humpback whales that migrate between Antarctica and eastern Australia. Their numbers have rebounded from a few hundred in 1968 to more than 40,000 today. Sea otters in Western Canada have also jumped from dozens in 1980 to thousands. Green turtles in Japan, grey seals and cormorants in the Baltic and elephant seals in the United States have all also made remarkable comebacks. However, “If we don’t tackle climate change and raise the ambition and immediacy of these efforts, we risk wasting our efforts,” Duarte, one of the authors of the study, told BBC News. The initial price tag on all this is hefty: $10 to $20 billion a year until the 2050 recovery date.

Excerpts from Oceans Can Recover by 2050, Study Shows, EcoWatch, Apr. 2, 2020

Assisted Evolution: Engineering Coral Reefs

Imagine ecologists cultivating whole new breeds of trees to restock a devastated wilderness…. Coral conservation has traditionally focused on minimizing damage from insults such as water pollution, invasive starfish, and destructive fishing or tourism. In the Caribbean, some conservationists have worked to “replant” damaged coral. But Gates and Van Oppen [two scientists]  have something more intrusive in mind. They want to try to alter the genetics of coral or the microbes that live on it. They dubb the effort “assisted evolution.”

Coral’s most remarkable characteristic—being an animal that is part plant—is also its Achilles’ heel in a hotter world. Normally, coral polyps—the individual coral organisms, which resemble a sea anemone the size of a pinhead—live in harmony with their algal partners, which help feed the polyps and give corals their bright colors. But during heat waves, the relationship sours. Overheated polyps perceive the algae as an irritant and eject them like unwanted squatters. The coral is left bleached, bone-white and starving. If the heat persists, the coral won’t take in new algae and can die.  The bond between coral and algae is complicated, however, and still not fully understood. Just 25 years ago, for example, researchers believed that coral housed just one variety of symbiotic algae. Now, they have identified hundreds. And they are just beginning to examine the role played by the coral’s microbiome, the menagerie of bacteria that inhabit a coral polyp.

Coral bleaching right.

But the complexity also offers multiple paths for scientists trying to forge a less fragile bond between coral and algae. Today, four major lines of research exist: One involves cross-breeding corals to create heat-tolerant varieties, either by mixing strains within a species or by crossing two species that would not normally interbreed. The second enlists genetic engineering techniques to tweak coral or algae. A third tries to rapidly evolve hardier strains of coral and algae by rearing them for generations in overheated lab conditions. A fourth approach, the newest, seeks to manipulate the coral’s microbiome…

In 2018, Cleves [scientist] became the first to report successfully using the CRISPR-Cas9 gene-editing tool on coral. CRISPR is often touted as a method for making genetically modified species. But Cleves says he isn’t interested in creating new kinds of coral. Rather, he sees CRISPR as a tool for deciphering the inner workings of coral DNA by knocking out, or disabling, genes one by one. He hopes to identify genes that might serve as “master switches” controlling how coral copes with heat and stress—knowledge that could help researchers quickly identify corals in the wild or in the laboratory that are already adapted to heat.

Either way, such efforts to re-engineer coral reefs make people such as David Wachenfeld, chief scientist for the Great Barrier Reef Marine Park Authority here, uneasy. The authority is supposed to protect the reef and regulate activities there. In the past, that meant a hands-off approach. Now, he concedes that “it is almost inconceivable that we’re not going to need these tools.” But, he adds, “That doesn’t mean I’m happy about any of this. This is crisis management.”

He ticks off a list of potential difficulties. Scientists focused on breeding heat-loving coral have to avoid weakening other key traits, such as coping with cold. Introducing a new coral on the scale needed to make a dent on a network of 2900 reefs spanning an area half the size of Texas is a daunting challenge. Even in its damaged state, the Great Barrier Reef still contains hundreds of millions of corals—enough to swamp the genetic impact of new coral species…

Could some kind of “super coral,” as some researchers have dubbed them, also run amok in delicate coral ecosystems.

Excerpts from  The Reef Builders, Science, Mar. 22, 2019

The Super-Corals

By some estimates, half of the world’s coral has been lost since the 1980s. Corals are delicate animals, and are succumbing to pollution and sediment from coastal construction. Also to blame are sewage, farmland run-off and fishing, all of which favour the growth of the big, fleshy algae that are corals’ main competitors for space. (The first two encourage algal growth and the third removes animals that eat those algae.) But the biggest killer is warming seawater. Ocean heatwaves in 2015, 2016 and 2017 finished off an astonishing 20% of the coral on Earth. This is troubling, for countless critters depend on coral reefs for their survival. Indeed, such reefs, which take up just a thousandth of the ocean floor, are home, for at least part of their life cycles, to a quarter of marine species. Losing those reefs would cause huge disruption to the ocean’s ecosystem. So researchers are looking for ways to stop this happening.

A growing number of scientists reckon that an entirely different approach to saving coral is needed. If oceans are changing faster than coral can adapt via the normal processes of evolution, why not, these researchers argue, work out ways to speed up such evolution  One way to do this would be selective breeding. Most species of coral spawn on just one or two nights a year, a process regulated by the lunar cycle, the time of sunset and the temperature of the water. The sperm and eggs released during spawning meet and unite, and the results grow into larvae that search for places where they can settle down and metamorphose into the stone-encased sea-anemone-like polyps that are the adult form. In the wild, the meeting of sperm and egg is random. Some researchers, however, are trying to load the dice. By starting with wild specimens that have survived a period of heat which killed their neighbours, they hope to breed heat resistance into the offspring.

This is the tack taken, for example, by Christian Voolstra of the Red Sea Research Centre in Thuwal, Saudi Arabia. He describes it as “making sure super papa and super mama meet and reproduce”. Corals bred in this way at the Hawaii Institute of Marine Biology, on Oahu, survive in water that is warm enough to kill offspring resulting from normal, random reproduction.

The reason corals die when the surrounding water gets too hot is that the microscopic algae and bacteria which live on and in their tissue, and are their main food sources, are sensitive to small changes in temperature. When stressed by heat these symbionts start producing dangerous oxidants. This causes the polyps to eject them, to ensure short-term survival. The reef thus turns ghostly white—a process called bleaching. Bleached coral is not dead. But unless the temperature then drops, the polyps will not readmit the algae and bacteria, and so, eventually, they do die.

Polyps that survive one such ordeal will, however, fare better if temperatures rise again. The second time around they have acclimatised to the change. Some species, indeed, can pass this resilience on to their offspring by a process called intergenerational epigenesis. The Hawaii Institute’s efforts to develop hardier corals thus include administering a near-death experience to them. Ruth Gates, the institute’s director, says the goal is to create reefs “designed to withstand the future”. The institute’s first such reef will probably be grown inside Biosphere 2, an enclosed ecosystem run by the University of Arizona.

Another approach, taken by the Australian Institute of Marine Science (AIMS) in Queensland, is to crossbreed corals from different places, to create hybrid vigour. The results of such crosses are unpredictable, but some survive heat greater than either of their parents could cope with.

The artificial breeding of corals is, though, constrained by their cyclical breeding habits, so researchers at the Florida Aquarium, on Tampa Bay, are trying to speed the process up. The operators of the aquarium’s “coral ark” nursery stagger lighting and temperature patterns to fool the animals into releasing their gametes on a day of the researchers’ choosing. This also permits the co-mingling of sperm and eggs that would not normally meet, thus allowing new varieties to be created. According to Scott Graves, the aquarium’s boss, half a dozen such varieties show most promise of heat resistance, but the team is generating thousands more, “just like a seed bank”, as a backup.

A coral’s fate is tied so closely to the algae and bacteria which live in its tissues that, as Dr Gates puts it, it is best to think of the whole thing as “a consortium of organisms”. This is why scientists at AIMS are keen also to produce algae that withstand higher temperatures without releasing the oxidants that lead coral to kick them out. They are doing so using a process which Madeleine van Oppen, a researcher at the institute, calls “directed laboratory evolution”. In the past few years her team have grown more than 80 generations of algae, repeatedly culling those organisms most susceptible to heat stress and also to acidification, another curse of a world with more carbon dioxide around than previously. The resulting algae release fewer toxins and photosynthesise better in warm water than do their wild brethren..

[A]fter the trauma of bleaching, polyps do extend a preferential welcome to algae that have greater levels of heat tolerance. His team are thus now using special lights to bleach corals. Polyps “stress hardened” in this way will be planted on wild reefs in coming months…

This raises the question of whether the genomes of coral, algae and bacteria might be edited for greater robustness. According to Dr Voolstra, more than ten laboratories around the world are trying to do so. His own team has successfully inserted genetic material into about 30 larvae of a coral called Acropora millepora. Editing corals’ heat thresholds in this way is, he reckons, about five years away.

Whether they are created by selective breeding or genetic engineering, supercorals, the thinking goes, would not need to be placed on reefs in astronomical numbers… That thought, however, does not please everybody. Some object in principle to the idea of releasing human-modified creatures into the wild, or feel that amelioration of this sort is a distraction from the business of reducing carbon-dioxide emissions. Others have pragmatic concerns—that corals bred to survive warming seas might suffer handicapping trade-offs. So regulators have been cautious. The Great Barrier Reef Marine Park Authority, for example, will probably require that the hybrid organisms AIMS hopes to test in the open reef are removed before they begin spawning. …[T]he alternative, of doing nothing, is the equivalent of “ just throwing our hands up in the air and saying, ‘OK, we’re prepared now not to have coral’.” For the world’s oceans, that loss would be catastrophic.

Excerpts from Accelerating Evolution: Refreshing Reefs, Economist, Mar. 17, 2018, at 75

Coral Reefs Preservation: Aichi Targets

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, 2016, at 57