Human beings are increasingly making their homes on the coasts of continents, but this demographic shift is taking a toll on a sensitive coastal ecosystem that is often overlooked: seagrass meadows. A new analysis of seagrass abundance around the world found that 27 percent of these meadows have disappeared since 1879, and the rate of loss is accelerating. The study’s authors write: “Seagrass loss rates are comparable to those reported for mangroves, coral reefs and tropical rainforests, and place seagrass meadows among the most threatened ecosystems on earth….. Our report of mounting seagrass losses reveals a major global environmental crisis in coastal ecosystems, for which seagrasses are sentinels of change” [Nature News].
Endangered species expert Susanne Livingstone notes that despite these losses seagrass rarely makes it into the public consciousness. “It’s probably because they’re not as sexy [as corals], they’re not as attractive,” she says. “They’re just as ecologically important if not more so” [Nature News]. Seagrass meadows provide grazing for a variety of marine animals, including the green turtle and the manatee-like dugong. The coastal areas also serve as nurseries for fish; both coral reefs and commercial fisheries would feel the impact if seagrass meadows vanish.
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Scientists have long known that coral reefs are being threatened by disease, global warming and other factors. Now a new study shows that that majority of Caribbean reefs have, in fact, been “flattened” in the past four decades, as ornate branched corals have died out and been replaced by flatter, fast-growing “weedy” species. Most of the reefs have lost all the intricate, tree-like corals that until the 1970s provided sanctuary for unique reef fish and other creatures, as well as protecting coastlines by sapping the energy of waves [New Scientist], according to the report, published in the journal Proceedings of the Royal Society B.
The coral reefs that were initially the most complex have almost been completely eliminated, says the researchers, who analysed changes in the structure of reefs using 500 surveys across 200 reefs conducted between 1969 and 2008. They found that 75 per cent of the reefs are now largely flat, compared with 20 per cent in the 1970s [ScienceDaily]. That’s bad news for sea life and storm defenses, says study coauthor Lorenzo Alvarez-Filip: “For many organisms, the complex structure of reefs provides refuge from predators…. This drastic loss of architectural complexity is clearly driving substantial declines in biodiversity, which will in turn affect coastal fishing communities” [ScienceDaily].
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A new study of fossilized coral reefs in Mexico has revealed that sea levels have risen abruptly in past epochs, which researchers say supports the theory that ocean levels could rise dramatically again in response to global warming. The study suggests that a sudden rise of 6.5 feet to 10 feet occurred within a span of 50 to 100 years about 121,000 years ago, at the end of the last warm interval between ice ages. “The potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability” in that period, the authors write [The New York Times].
Other researchers have previously found evidence of rapid sea level rise as ice ages gave way to more temperate eras, causing vast ice sheets to melt. But because the coral shows evidence from a warmer interglacial period—similar to the one we’re in currently—the find boosts the chances that today’s melting ice sheets could trigger rapid sea-level rise, the study authors say [National Geographic News]. However, not everyone is convinced that the authors have proven their case. Some experts argue that the researchers haven’t definitively shown that the coral fossils date from 121,000 years ago.
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The blank spaces on the map of Google Earth are being filled in, as the company announced today that many of the flat blue oceans on its global replica have been replaced with detailed maps of the ocean floor. Now, users can soar from undersea mountains to the depths of the Marianas Trench, and can explore coral reefs and shipwrecks. Sylvia Earle, an oceanographer who was involved in the effort, says: “I cannot imagine a more effective way to inspire awareness and caring for the blue heart of the planet than the new Ocean in Google Earth. For the first time, everyone from curious kids to serious researchers can see the world, the whole world, with new eyes,” she added [BBC News].
Google’s usual satellite imaging can’t peer through deep water to map the seabed. Instead, sound is the tool of choice when mapping the ocean floor. Passing sonar arrays over every patch of ocean is beyond even Google’s means, so it has had to rely on the US navy for much of the information. As a result, some “sensitive” areas are blank. Other navies and research institutions around the world also provided data [New Scientist]. But the marine scientists who collaborated with Google note that only 5 percent of world’s sea floor is mapped in detail, and say they hope the Google Ocean will inspire the public to support further marine exploration.
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President Bush will establish three national monuments in the Pacific Ocean today in a move that will protect a vast marine ecosystem from mining, oil exploration, and commercial fishing. With the stroke of a pen this afternoon, Bush will have set aside more square miles of ocean for protection than any other political leader in history. The three new monuments, surrounding far-flung islands, reefs and atolls scattered across the Pacific, will add 195,000 square miles of protected waters to the nearly 140,000 square miles around the Northwest Hawaiian Islands that Bush protected in 2006 [Los Angeles Times]. The United States has authority over these waters because the tiny atolls and islands are U.S. territories.
The three areas are thronged with fish, sharks, coral reefs, and other forms of sea life, all of which will benefit from the new protections. Blue-water fish such as yellowfin, bigeye tuna, and marlin–all in decline–will be big winners because they breed in these waters. So will sharks, birds, turtles, and dolphins accidentally caught by the tuna long-line fleets [ScienceNOW Daily News]. One of the new national monuments also encompasses the deepest location of the earth’s crust. The Marianas Trench, which reaches depths of more than 36,000 feet in some locations, contains undersea volcanoes and hydrothermal vents around which cluster tough organisms that can withstand high temperatures and harsh chemicals. These “extremophiles” are of interest to scientists who think they signal forms that extraterrestrial life could take.
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The growth of the world’s largest coral reef system has slumped to its slowest rate in at least four centuries, according to a new report in Science [subscription required]. Researchers studying coral colonies in the Great Barrier Reef found that calcification, the process that builds the reefs, has dropped 13.3 percent since 1990. They fear the decline is indicative of a worldwide threat to coral reefs caused by rising seawater temperatures and ocean acidification. The loss of coral growth threatens food webs and may lead to “precipitous” changes in biodiversity, the authors said [Bloomberg].
The Great Barrier Reef along the northeast coast of Australia stretches more than 1,200 miles and is visible even in space. Coral reefs, delicate undersea structures resembling rocky gardens made by tiny animals called coral polyps, are important nurseries and shelters for fish and other sea life. They also protect coastlines, provide a critical source of food for millions of people, attract tourists and are potential storehouses of medicines for cancer and other diseases [Reuters]. Massive coral reefs materialize from the gradual accumulation of calcium carbonate by billions of coral polyps over thousands of years.
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While Indonesia is still rebuilding following the devastating 2004 earthquake and tsunami that killed more than 130,000 people on the island of Sumatra alone, scientists are warning that several other major earthquakes are likely to occur in the region over the next decades. A new study examined the growth records of coral reefs off the coast of Sumatra, and say they show evidence of repeated bursts of earthquakes that relieve pressure on the Sunda fault. A shock in 2007 may be the beginning of a new cycle, researchers say.
Says study coauthor Kerry Sieh: “If previous cycles are a reliable guide we can expect one or more very large west Sumatran earthquakes … within the next two decades” [Reuters]. As if to illustrate the point that the Indian Ocean is seismically active, reports are coming in that a 5.9 magnitude earthquake struck last night off the coast of Sumatra; happily, there have been no reports of casualties or damages, and authorities say there is no risk of a tsunami.
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The newly elected president of the Maldives, the island chain south of India, says his country must start saving up money to buy a new homeland, in case global warming causes sea levels to rise so much that the waves submerge the archipelago entirely. Says Maldivian President Mohamed Nasheed: “We can do nothing to stop climate change on our own and so we have to buy land elsewhere. It’s an insurance policy for the worst possible outcome…. We do not want to leave the Maldives, but we also do not want to be climate refugees living in tents for decades,” he said [The Guardian].
The Maldives are the lowest-lying nation on the planet: most of the islands are only a few feet above sea level, and the highest point, in the capital city of Malé, is about seven feet above sea level. But the white sandy beaches are a major tourist attraction bringing in billions of dollars every year…. Mr Nasheed’s plan is to create a “sovereign wealth fund” using tourism revenues to buy land so that future generations will have somewhere to rebuild their lives if they have to leave. He wants somewhere within the region, where the culture is similar – possibly India or Sri Lanka [BBC News]. However, Nasheed also mentioned Australia as a possibility, because of the vast swaths of unoccupied land on that continent.
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Several rare varieties of staghorn coral have begun mating across species lines and are creating surprisingly robust hybrids, according to a new study; researchers believe the unusual step is an effort to adapt to changing ocean conditions and avoid extinction. The findings are an unexpected piece of promising news about coral reefs, which usually make the headlines for their potential fate as one of the first victims of global warming.
Coral reefs around the world are under pressure from pollution and gradually warming oceans, and researchers have worried that rare species are particularly vulnerable to extinction. But in the case of these staghorns, the new study shows that when faced with a shortage of mates of their own kind, these rare corals have cast a wider net and started cross-breeding with other coral species, producing hybrids. “It pushes the boundaries of our traditional understanding of species,” said a researcher, Zoe Richards. “They are being a little promiscuous” [Sydney Morning-Herald].
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President Bush has proposed protecting vast swaths of marine territory in the South Pacific from commercial fishing and offshore drilling, in a move that some environmentalists have said could earn him a legacy as the “Teddy Roosevelt of the seas.” This week, Bush is expected to ask his Cabinet for comments on conservation proposals for marine ecosystems around the Northern Mariana islands, the Line Islands, and American Samoa.
While the Bush administration’s environmental record has generally received harsh criticism from environmentalists, these proposals are being seen as a cause for celebration. “We have every expectation that the president will move forward on protecting these places sometime in the fall,” said Diane Regas, ocean program director at Environmental Defense Fund. “Today, we put the champagne on ice, and we will pop it open.” Two years ago, the president made a huge swath of the Northwestern Hawaiian Islands a national monument, barring fishing, oil and gas extraction and tourism from its waters and coral reefs. The area is the single largest conservation area on the planet [AP].
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Coral reefs can resemble underwater monuments, with strong towers and meandering walls that stand firm against the tides. But a new study says that if global warming causes ocean water to become more acidic those elaborate structures may crumble because the cement-like binding agent that holds the reefs together won’t be able to form in those inhospitable waters.
Most of the world’s coral reefs aren’t yet showing signs of this degradation, as ocean pH is slow to change and reefs form slowly. But researchers got a chance to peer into the possible future in an area of the eastern Pacific off Central America… where the water is more acidic than elsewhere, thanks to the upwelling of carbon-dioxide-rich waters. Coral reefs in this region are poorly developed and tend to erode rapidly [The New York Times].
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Researchers are sounding the alarm about the world’s coral reefs, declaring that one-third of reef-building species are now threatened with extinction. If the news sounds familiar, it’s because researchers published a separate report about the dire condition of reef ecosystems in U.S. waters earlier this week.
The new study widens the focus to look at all coral reefs throughout the world’s oceans, and also issues a terrifying diagnosis: Unless action is taken, it is conceivable that the “rainforests of the ocean” could be wiped out this century.… “Whether corals actually go extinct this century will depend on the continued severity of climate change, extent of other environmental disturbances, and the ability of corals to adapt” [Telegraph], researchers write in the journal Science [subscription required].
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Put this one in the bad news file: A new report from the National Oceanic and Atmospheric Administration (NOAA) states that half of the coral reef ecosystems in U.S. waters are ailing, and that their condition has declined precipitously in the three years since the last report. Since 2005 the Caribbean has lost 50 percent of its corals primarily because of rising ocean temperatures, which are linked to global warming, the report says.
Besides being a marvel of the natural world, the coral reefs serve as breeding grounds for many of the world’s seafood species and act as indicators of overall ocean health…. [NOAA official Timothy] Keeney said 25 percent of all marine species need coral reefs to live and grow, while 40 percent of the fish caught commercially use reefs to breed. “If we lose the reefs, you lose a very significant and important habitat,” Keeney said [AP].
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