Oceans and the Carbon Dioxide Threat - NIMBY to Co2
Human Shadows on the Seas
L. Madin/Woods Hole Oceanographic Institution
INTERLOPERS TAKE HOLD Invaders like Pacific oysters, left, and the comb jelly, right, have squeezed out native species in some seas.
By ANDREW C. REVKIN
Published: February 26, 2008
In 1980, after college, I joined the crew of a sailboat partway through a circumnavigation of the globe. Becalmed and roasting one day during a 21-day crossing of the western Indian Ocean, several of us dived over the side. Within a few swimming strokes, the bobbing hull seemed a toy over my shoulder as I glanced back through my diving mask. Below me, my shadow and the boat’s dwindled to the vanishing point in the two-mile-deep water. Human activity seemed nothing when set against the sea itself.
Mapping the Other 70 Percent
Slide Show Coral Reefs and What Ruins Them (February 26, 2008)
Dot Earth: Our Exhausted Oceans (February 25, 2008)
Just a few weeks later, on an uninhabited island in a remote part of the Red Sea, I was proved wrong. The shore above the tide line was covered with old light bulbs, apparently tossed from the endless parade of ships over the years.
Now scientists are building the first worldwide portrait of such dispersed human impacts on the oceans, revealing a planet-spanning mix of depleted resources, degraded ecosystems and disruptive biological blending as species are moved around the globe by accident and intent.
A paper in the Feb. 15 issue of the journal Science is the first effort to map 17 kinds of human ocean impacts like organic pollution, including agricultural runoff and sewage; damage from bottom-scraping trawls; and intensive traditional fishing along coral reefs.
About 40 percent of ocean areas are strongly affected, and just 4 percent pristine, according to the review. Polar seas are in the pristine category, but poised for change. Some human impacts are familiar, like damage to coral reefs and mangrove forests through direct actions like construction and subtler ones like the loss of certain fish that shape ecosystems.
Others were a surprise, said Benjamin S. Halpern, the lead author and a scientist at the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. He said continental shelves and slopes proved to be the most heavily affected areas, particularly along densely populated coasts.
The most widespread human fingerprint is a slow drop in the pH of surface waters around the world as a portion of the billions of tons of carbon dioxide added to the atmosphere from fuel and forest burning each year is absorbed in water, where it forms carbonic acid.
That progressive shift in ocean chemistry could eventually disrupt shell-forming plankton and reef-building species, particularly where other impacts, including rising temperatures from human-caused global warming, create simultaneous stresses, many marine biologists say.
“I study this stuff all the time and didn’t expect the impacts to be as pervasive as we found,” Dr. Halpern said.
The review provides a baseline necessary for tracking further shifts, he said. It also identifies some unanticipated trouble spots, similar to terrestrial biodiversity “hot spots” that environmental groups have identified over the years.
Such an analysis is long overdue, many marine biologists said in interviews. People’s conservation concerns have mainly focused on land, even though the seas cover two-thirds of the planet and are a vital source of food and pleasure.
Sylvia Earle, an oceanographer and National Geographic Society “explorer in residence,” said people care only about what they know. A big question now is whether such surveys are providing too little knowledge, too late.
“We learned more about the nature of the ocean in the latter part of the 20th century than during all preceding human history,” Dr. Earle said. “But we also lost more.”
A separate mapping effort published this month focused on introduced invasive species and found that 84 percent of the world’s coastal waters were affected, with Arctic waters next in line as shipping there grows in a warming world.
More than half the introduced species that take hold are having deleterious effects, said Jennifer Molnar, a conservation scientist at the Nature Conservancy who led that study, which was published in the journal Frontiers in Ecology and the Environment.
The House of Representatives is considering legislation aimed at tightening controls on the ballast water that stabilizes freighters when they are not full. Ballast water and organisms clinging to hulls and anchors have been the source of many costly marine invasions, including the introduction of zebra mussels to American waters and the comb jelly, a small jellyfish, to the Black Sea.
That species exploded after its accidental introduction in 1993, vacuuming up plankton until it made up 90 percent of the sea’s life by weight, causing fisheries to collapse. Its population there has since crashed, partly because of the arrival of a species of jellyfish that eats the established invader.
In May, invasive species will be a significant subject at the meeting of the world’s nations to assess the progress of the Convention on Biological Diversity.
Even as efforts to gauge human effects intensify, other scientists are simply trying to survey marine species large and small, an enormous task given how little is known about the oceans.
The hub for this work is the Census of Marine Life, a 10-year project initiated under the Alfred P. Sloan Foundation that is scheduled to produce a first synthesis report on marine species in 2010.
More than 2,000 scientists from 81 countries have chipped in, said Michael Feldman of the Consortium for Ocean Leadership, a group in Washington running the global project.
Since 2003, the project has discovered more than 5,300 species, Mr. Feldman said, adding: “We’ve only been able to formally describe a few hundred so far. They’re still discovering things at a rate we don’t even know what to do with.”
There is a growing sense of urgency among marine researchers in cataloging what is there, what is being threatened and what is already a fading memory.
Recent books, including “The Unnatural History of the Sea” by the marine scientist Callum Roberts, have painted vivid portraits of how much more abundant marine resources were a few generations ago, a situation well known to anyone who has worked in a fishery.
In the 1970s, I worked summers for the Rhode Island marine fisheries agency. At one point, I was tagging lobsters as part of an effort to find ways to revive depleted populations. A crusty old custodian in the laboratory, Jim Pimentel, reminisced about how different things had been a few decades earlier.
“We used lobsters for cod bait,” Mr. Pimentel said.
Looking ahead, Jane Lubchenco, a marine biologist at Oregon State University, said a wide array of efforts is required to sustain productive, if altered, seas. Among the needed steps, Dr. Lubchenco said, are expanding protected marine areas and curbing pollution, including carbon dioxide.
“We cannot go back in time to some past system,” Dr. Lubchenco said. “But we can protect and restore the functioning of today’s ecosystems so they can be as healthy, productive and resilient as possible.”
Coral Reefs and What Ruins Them
A healthy reef often appears, at first glance, to be an empty reef with only a few of the colorful fish usually associated with coral reefs swimming around. That is because the fish are hiding, trying to avoid becoming a meal for predators like this red snapper.
Researchers who studied a string of Pacific Ocean atolls are painting the first detailed picture of pristine coral reefs and how they can be disrupted by people — particularly, they said, by fishing.
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OBSERVATION Coral in the Palmyra lagoon. More Photos >
The researchers, from the Scripps Institution of Oceanography and elsewhere in the United States and abroad, surveyed every form of life last summer in the northern Line Islands, a chain south of Hawaii. Their survey encompassed everything from microbes to sharks and other big fish at the top of the food chain.
“Reefs without people” were healthier than populated reefs, they say in a report to be posted Wednesday in the online Public Library of Science Biology. The ecosystems at Kingman and Palmyra, the northernmost and least populated atolls, are dominated by large predators like sharks and groupers, and corals there are robust, they said, while Tabuaeran and Kiritimati to the south, the most populated atolls, are characterized by fleshy algae, small plankton-eating fish and degraded corals.
In a commentary also published online, Nancy Knowlton and Jeremy B. C. Jackson, coral experts at Scripps and the Smithsonian Institution, said the new work was notable because it produced data at sites “across a full spectrum of human impacts.” Without this kind of data, they write, studying coral reefs is like trying to discern the ecological structure of the Amazon rain forest by looking at the cattle ranches and soybean fields that have replaced much of it.
Actually, they write, it is even worse. Scientists can still visit vast areas of intact rain forest and have decades of data from earlier researchers. “The situation is very different for the oceans,” Dr. Knowlton and Dr. Jackson wrote, because degradation of ocean ecosystems is so pervasive, and underwater observation is relatively recent. As a result, they said, scientists disagree over the relative importance for coral of local factors like overfishing and pollution as against global problems like climate change and the acidification of oceans it causes.
The Line Islands work will not settle those arguments. But the scientists noted great differences in the fish communities at inhabited and uninhabited reefs, which they attributed to fishing pressure on shark, grouper, snapper and other large predators, said Enric Sala, an ecologist formerly at Scripps and now at the National Council for Scientific Research in Spain.
Kingman is unpopulated — in fact, none of it is permanently above water. Palmyra was dredged extensively in the 1940s, the researchers said, and fishing has occurred there, but today both atolls are protected by the United States Fish and Wildlife Service as part of the Pacific/Remote Islands National Wildlife Refuge. A camp at Palmyra, with a capacity of 20, has its own sewage treatment center.
Tabuaeran, with a growing population estimated in 2005 at 2,500, and Kiritimati, with 5,100 people and growing even faster, are part of the Republic of Kiribati. People there subsist on fishing and have no sewage treatment facilities.
At Kingman and Palmyra, the ocean ecosystem is dominated by large top-predator fish, species “virtually absent” at Tabuaeran and Kiritimati, also known as Christmas Island. The researchers said this was the typical pattern elsewhere in the world, except the northwestern Hawaiian Islands.
They attributed it to fishing pressure which, they said, “tends to disproportionately reduce densities of longer-lived, larger-bodied individuals.”
The pattern in the uninhabited atolls, though, “is similar to what we see in Yellowstone — the landscape of fear,” Dr. Sala said. “In Yellowstone there are all these wolves, and the deer are much more attentive.”
As a result, he said, small fish spend much of their time hiding. “When people see photos they say, ‘Well, the water is empty,’ ” he said. “For me, it’s prettier because the corals are healthy and clean and you don’t see seaweed in the reefs and you see these big snappers and sharks.” There are far more fish on degraded reefs, he said, but they are far smaller. “The percentage of the bottom cover by large corals declines, the seaweed takes over, then the microbes become much more abundant,” he said.
The researchers said coral cover, density and species richness were highest at Kingman and lowest at Kiritimati. Coral disease was most prevalent at Kiritimati, they said.
Dr. Sala acknowledged that by the standards of the Caribbean and other heavily exploited areas, Tabuaeran and Kiritimati are in pretty good shape. But, he added, “there are 5,000 people living in Christmas and fishing there,” enough “to transform the whole ecosystem.”
At the moment, the assessment leaves the researchers with questions as well as answers. For example, reefs like Tabuaeran and Kiritimati don’t seem to survive as well in episodes of disease or bleaching. Is it because of fishing? To find out, the researchers wrote, they will have to measure how coral growth and fish productivity respond to fishing pressure and how they all interact with episodes of warm water.
But for Dr. Sala, the reefs are like “ecological machines” whose parts include plants, fish, corals and microbes. “You can hit the system with a disturbance, but the system comes back,” he said. But if pieces — like big predatory fish — are removed, he said, “the machine is going to malfunction.”
As a result, he said, the new work “is an argument for marine reserves large enough to include healthy populations of top predators.”
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Re: Oceans and the Carbon Dioxide Threat - NIMBY to Co2
Gee, I'm not going to read the whole article, but there has always been one thing that bugs me about environmentalism and that is the concept of the "static biosphere". When they say "native species are displaced by other species," do they think that those "native species" once displaced some OTHER "native species"?
Otherwise, I like all the pretty animals, and stuff, but the "world is dying" crap is getting old.
I'm baaack! See my Hot Milk For Breakfast blog under Social Groups for more details
Re: Oceans and the Carbon Dioxide Threat - NIMBY to Co2
Exactly. Does not the extinction of a species fit precisely within the framework of Darwinist thought, which seems to be the pervasive train of belief within this movement?
Originally Posted by Phaedrus