When the Deepwater Horizon oil rig blew in 2010, it spewed some 200 million gallons of oil into the Gulf of Mexico. In order to break up the slick, another 1.84 million gallons of dispersant was added to the mix. This one-two punch of toxic chemicals devastated coastal ecosystems [pdf], but how would such a chemical bombardment affect underwater ecosystems like coral reefs? According to a new study, the
picture is no prettier.
Researchers at the Mote Marine Laboratory in Florida tested the effects of Deepwater Horizon-type oil and the dispersant used to clean it up, Corexit® 9500int, on coral larvae in the lab to replicate what may have happened following the spill. Larvae colonize reefs by sampling a surface, sticking to it and then changing into a polyp to get growing. They do this based on chemical cues in the water. Adding oil and dispersant, it turns out, severely hinders this sensitive settlement process.
Elkhorn coral infected with white pox.
What’s the News: Over the past decade, diseases, pollution, and warming waters have put coral populations across the globe in a dramatic decline. In an extreme case, the population of elkhorn coral, considered one of the most important reef-building corals in the Caribbean, has decreased by 90–95 percent since 1980, partly due to a disease called white pox.
Now, scientists have traced this lethal disease back to humans. Human feces, which seep into the Florida Keys and the Caribbean from leaky septic tanks, transmit a white pox-causing bacterium to elkhorn coral, researchers report in the journal PLoS ONE. “It is the first time ever that a human disease has been shown to kill an invertebrate,” ecologist James Porter told Livescience. “This is unusual because we humans usually get disease from wildlife, and this is the other way around.”
The flooding created by enormous downpours near Brisbane in eastern Australia shows no signs of abating, and that region is now bracing for things to go from bad to worse.
Heavy rains pounded Brisbane’s region, called Queensland, in December. And things really started to get bad yesterday, when flooding caused by the constant rain sent a wall of water—evocatively being called an “inland tsunami”—crashing through the nearby town of Toowoomba. Brisbane, which is Australia’s third-largest city at about two million people, in next in the crosshairs.
Normally it is protected from periodic flooding of the Brisbane river by the Wivenhoe dam, 80 kilometres [50 miles] away. But Wivenhoe is already 81 per cent over capacity after last month’s heavy rains saturated Queensland. To save Brisbane from flooding, officials began releasing water from Wivenhoe last month. But because of the inland tsunami now hurtling towards the city, officials have increased the amount of water released from 140 million tonnes yesterday to 344 million tonnes today. [New Scientist]
But there’s only so much they can do. As of this morning, the Christian Science Monitor reports at least 30 deaths and 78 missing, with the number expected to grow as flooding threatens Brisbane.
[Brisbane] Mayor Campbell Newman warned 6,500 homes, businesses and other properties were likely to be flooded by Thursday. “Today is very significant, tomorrow is bad, and Thursday is going to be devastating for the residents and businesses affected,” he said. [BBC News]
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In the western Caribbean, some coral reefs have turned into eerie white ghost towns.
Scientists with the Smithsonian Tropical Research Institute have documented a major bleaching event in the reefs near Panama and the island of Curaçao. Such bleaching occurs when a reef loses the tiny photosynthetic algae that typically live in the coral, providing it with food (and color). Bleaching occurs when coral is under stress, most typically due to higher ocean temperatures. And this was a hot summer.
Abnormally warm water since June appears to have dealt a blow to shallow and deep-sea corals that is likely to top the devastation of 2005, when 80% of corals were bleached and as many as 40% died in areas on the eastern side of the Caribbean. [ScienceNOW]
This past summer was hot. Russia burned, New York City experienced the hottest summer on record, and residents of the northern hemisphere in general agreed that a cool breeze would be rather welcome. Now more extensive climate data is coming in for 2010, and guess what? Scientists have confirmed that it was hot.
According to NASA’s Goddard Institute for Space Studies, the first 8 months of 2010 is the warmest such January-to-August period in climate records stretching back 131 years. This period was nearly 0.7˚C warmer than the average temperature from 1951 to 1980. (NOAA announced roughly the same finding today, using many of the same temperature stations but a different analysis method.) [ScienceNOW]
Researchers say that El Nino conditions in the Pacific Ocean are partly to blame for raising temperatures globally this past year. But, of course, man-made climate change is the larger culprit. This summer the Arctic sea ice shrank very quickly because the ice was already thin; at the end of the summer melt the Arctic ice area was the third smallest on record.
At its smallest extent, on 10 September, 4.76 million sq km (1.84 million sq miles) of Arctic Ocean was covered with ice — more than in 2007 and 2008, but less than in every other year since 1979. [BBC]
The tiny islands of the Pacific Ocean appear to be the very the picture of climate change vulnerability—some rise such a short distance above current sea level that it seems like any rise would swallow them up. The Earth’s climate system, though, is a great deal more complex than the simplistic rhetoric that fills the political echo chamber. That’s demonstrated again in a new study that argues some the Pacific’s low-lying islands are actually increasing slightly in land area rather than decreasing. It’s good news, yes—but not without caveats.
First, the specifics. Arthur Webb and Paul Kench published their work, based on decades of aerial and satellite photos, in the journal Global and Planetary Change. During the years spanned by those images, the sea level in the area has been rising by about 2 millimeters per year. Nevertheless, they say that 23 of the 27 Pacific islands they studies either held firm in land area or saw a slight increase. How could this be?
Unlike the sandbars of the eastern US coast, low-lying Pacific islands are made of coral debris. This is eroded from the reefs that typically circle the islands and pushed up onto the islands by winds, waves and currents. Because the corals are alive, they provide a continuous supply of material. “Atolls are composed of once-living material,” says Webb, “so you have a continual growth.” Causeways and other structures linking islands can boost growth by trapping sediment that would otherwise get lost to the ocean [New Scientist].
Over the weekend a huge Chinese freighter loaded down with coal and fuel oil crashed into part of the Great Barrier Reef off the Australian coast. Today, salvage teams are still struggling with how to extricate the Shen Neng 1 without dumping any more of its dirty cargo into the delicate marine ecosystem.
The ship had left the port of Gladstone just a few hours before striking the reef in Douglas Shoal. It ran aground in a restricted zone of the marine park, almost 30km [18.6 miles] from the authorised shipping channels it should have been using [Sydney Morning Herald]. Both the main engine and the rudders sustained serious damage. While rescuers debate how to orchestrate a salvage operation, the Shen Neng 1 has slid another 20 or 30 yards along the reef, destroying more coral in its path.
The Convention on International Trade in Endangered Species (CITES) continues through Thursday of this week, and the fallout continues today.
On Friday we reported that the bluefin tuna trade ban failed thanks in large part to Japanese diplomatic efforts, denying new protections to the endangered fish, but also noted that the question of opening the ivory trade had yet to see a vote. Over the weekend the convention voted down those ivory proposals put forth by Tanzania and Zambia, which would have allowed one-off sales of ivory from government stockpiles. The ivory trade was banned in 1989, but two sales have since been granted to nations showing effective conservation [BBC News]. However, fears that such sales encourage poaching led the meeting’s attendees to reject the new proposals.
While most conservation groups lobbied against the ivory proposal, another of their pet causes—offering more protection for corals against harvesters who sell them as jewelry—failed at CITES. The proposed restrictions would have stopped short of a trade ban but required countries to ensure better regulations and to ensure that stocks of the slow-growing corals, in the family coralliidae, were sustainably harvested [The New York Times]. The provision garnered 64 “yes” votes to 59 for “no,” but needed a two-thirds majority to pass.
80beats: Bluefin Tuna is Still on the Menu: Trade Ban Fails at International Summit
80beats: Is Ivory Season Starting, Just As Tuna Season’s Ending?
80beats:Scientists Say Ban Atlantic Bluefin Tuna Trade–and Sushi Chefs Shudder
80beats: Elephant-Lovers Worry About Controversial Ivory Auctions in Africa
Image: flickr / wwarby
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.
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].