tagged w/ Human Footprint
-
A low-oxygen "dead zone" in the Gulf of Mexico (map) is causing sexual deformities in fish, a new study says.
The Gulf dead zone occurs when agricultural and waste runoff from the Mississippi River spark blooms of algae and microbes. These organisms gobble up oxygen, starving other marine life and creating huge swaths of "dead" ocean.
Between 2006 and 2007, nearly a quarter of female Atlantic croaker fish caught in the northern Gulf's dead zone had developed deformed, testes-like organs instead of ovaries.
(See "Sex-Changing Chemicals Found in Potomac River.")
It's unclear how long the fish were living in hypoxic—or low oxygen—waters before they began developing such sexual defects. But lab experiments showed that ten weeks of exposure is all that's needed.
The Gulf dead zone, which occurs annually, generally persists between May and September, and has more than doubled since the 1980s.
This zone, which often fluctuates in size, currently occupies a patch of ocean larger than the state of Connecticut. (Related: "Gulf of Mexico 'Dead Zone' Is Size of New Jersey [2005].")
Low Oxygen Screws Up Fish Hormones
Lab analysis of the fish revealed that the masculinized female croakers had decreased levels of a key chemical found in the brain and ovaries called aromatase.
This enzyme regulates the production of the female sex hormone estrogen, which is critical for proper development of the ovaries.
The brain uses about 20 percent of the oxygen that the croakers breathe, said study co-author M.S. Rahman, a marine biologist at the University of Texas in Austin's Marine Science Institute.
"If the oxygen levels go down, it affects the brain and the neurohormones and neuropeptides that it produces."
In croakers and many other fish species, the sex organs are male by default—estrogen exposure is required to transform the testes into ovaries.
Rahman and colleague Peter Thomas, also at the University of Texas, think that when the croaker's estrogen levels were reduced as a result of hypoxia, some of the cells in the animals' ovaries reverted back to testicular tissue.
(Also see "Mercury Poisoning Makes Birds Act Homosexual.")
The sex organs of the masculinized female fish were smaller and less developed than normal male testes. While some of malformed organs even contained sperm, they were incapable of fertilizing normal female eggs, Rahman said.
The study also found that male croakers were affected by hypoxia, although to a lesser degree. Males caught in the Gulf dead zone, as well as those bred in hypoxic lab conditions, had smaller than average testes and lower sperm counts, according to the study, published online recently in the journal Proceedings of the Royal Society B.
Sexual impairments of both male and female croakers help explain the low hatching rates among fish exposed to dead zones, the scientists added.
cont.A low-oxygen "dead zone" in the Gulf of Mexico (map) is causing sexual... more
-
-
A historic deal to halt the mass extinction of species was finally agreed last night in what conservationists see as the most important international treaty aimed at preventing the collapse of the world's wildlife.
Delegates from more than 190 countries meeting in Nagoya, Japan, agreed at the 11th hour on an ambitious conservation programme to protect global biodiversity and the natural habitats that support the most threatened animals and plants.
After 18 years of debate, two weeks of talks, and tense, last-minute bargaining, the meeting of the UN Convention on Biodiversity agreed on 20 key "strategic goals" to be implemented by 2020 that should help to end the current mass extinction of species.
Related articles
•Michael McCarthy: The Nagoya deal shows the world has at last woken up
•Michael McCarthy: With the death of the Emperor we mourn the passing of an ideal
Search the news archive for more stories
The sweeping plan to put the brakes on the loss of species includes a set of new targets to be implemented by the end of the decade that will give greater protection to the natural world and enshrine the benefits it gives to humankind in a legally binding code of protection.
"This agreement reaffirms the fundamental need to conserve nature as the very foundation of our economy and our society," said Jim Leape, director general of the conservation group WWF International.
"Governments have sent a strong message that protecting the health of the planet has a place in international politics, and countries are ready to join forces to save life on Earth," Mr Leape said.
One of the 20 targets agreed by the delegates was to extend national parks to increase the area of protected land in the world from 12.5 per cent to 17 per cent, and the area of protected oceans from 1 per cent to 10 per cent by 2020. Another target is to lift threatened species from the risk of extinction.
Environment ministers from around the globe also agreed on rules for sharing the commercial benefits of nature's genetic resources between governments and companies, a key trade and intellectual property issue that could be worth billions of dollars in new funds for developing nations.
One idea enshrined in the new protocol is to set up a special fund from a proportion of the profits made from commercial products derived from biological material collected decades or even centuries ago from natural habitats in the developing world.
Caroline Spelman, Britain's Environment Secretary, said last night from Nagoya: "We have also agreed an historic protocol which has been 18 years in the making, establishing a regime where developing countries will allow access to their genetic and natural resources in return for a share of the benefits for their use."
This feature of the agreement was the biggest stumbling block to a deal because of concerns by developing nations that they would miss out on the revenues generated by Western companies that discover new drugs and medicines derived from studying the chemistry and genetics of species living in regions rich in biodiversity.
Developing nations, particular in Africa, had argued they had not benefited in the past from their natural resources which had been developed into lucrative products by wealthy Western countries.
Poorer countries had insisted that the cost of increasing their spending on the conservation of natural habitats had to be offset by some financial mechanism that paid them for the benefit of the genetic resources they were protecting.
Johansen Voker of Liberia's Environmental Protection Agency
had said: "The forest and the other biological resources we have serve the general interests of the global environment. So we expect assistance to be able to effectively conserve our environment for the common good of the world community."
The Nagoya meeting agreed to establish an International Regime on Access and Benefit Sharing of Genetic Resources to lay down the basic ground rules on how nations co-operate in obtaining genetic resources from animals, plants and fungi.
Achim Steiner, head of the UN Environment Programme, which administers the Convention on Biological Diversity, said: "This is a day to celebrate in terms of a new and innovative response to the alarming loss of biodiversity and ecosystems. And a day to celebrate in terms of opportunities for lives and livelihoods in terms of overcoming poverty and delivering sustainable development."
Ms Spelmen said the agreement sets out a plan to halt the loss of habitats that provide essential biological services for the benefit of people, such as the supply of fresh water. This, she insisted, would help to eradicate poverty. "We have also secured an agreement to link climate change, global poverty and biodiversity together in protecting the world's forests, which is essential if we are to achieve our aims in these areas," she said.
Last week, a report by the Zoological Society of London warned the populations of mammals, birds, reptiles, amphibians and fish have declined by 30 per cent over 40 years and that one-fifth of all vertebrate species are threatened with extinction.
cont.A historic deal to halt the mass extinction of species was finally agreed last night... more
-
-
You don't have to be an environmentalist to care about protecting the Earth's wildlife.
Just ask a Chinese fruit farmer who now has to pay people to pollinate apple trees because there are no longer enough bees to do the job for free.
And it's not just the number of bees that is dwindling rapidly - as a direct result of human activity, species are becoming extinct at a rate 1,000 times greater than the natural average.
The Earth's natural resources are also suffering.
In the past few decades alone, 20% of the oceans' coral reefs have been destroyed, with a further 20% badly degraded or under serious threat of collapse, while tropical forests equivalent in size to the UK are cut down every two years.
These statistics, and the many more just like them, impact on everyone, for the very simple reason that, in the end, we will all foot the bill.
Costing nature
For the first time in history, we can now begin to quantify just how expensive degradation of nature really is.
Drivers of biodiversity loss
Land use change - for example cutting down forests that provide essential water regulation, flood protection and carbon storage, to make way for agriculture
Over exploitation - for example over-fishing or intensive farming that leads to soil degradation
Invasive species - for example the introduction of non-indigenous species that crowd out endemic insect populations
Climate change - for example rising temperatures that cause more extreme weather conditions.
A recent, two-year study for the United Nations Environment Programme, entitled The Economics of Ecosystems and Biodiversity (Teeb), put the damage done to the natural world by human activity in 2008 at between $2tn (£1.3tn) and $4.5tn.
At the lower estimate, that is roughly equivalent to the entire annual economic output of the UK or Italy.
A second study, for the UN-backed Principles for Responsible Investment (PRI), puts the cost considerably higher. Taking what research lead Dr Richard Mattison calls a more "hard-nosed, economic approach", corporate environmental research group Trucost estimates the figure at $6.6tn, or 11% of global economic output.
This, says Trucost, compares with a $5.4tn fall in the value of pension funds in developed countries caused by the global financial crisis in 2007 and 2008.
Of course these figures are just estimates - there is no exact science to measuring humans' impact on the natural world - but they show that the risks to the global economy of large-scale environmental destruction are huge.
Natural services
The reason the world is waking up to the real cost of the degradation of the Earth's wildlife and resources - commonly referred to as biodiversity loss - is because, until now, no one has had to pay for it.
Businesses and individuals have largely operated on the basis that the natural resources and services that the planet provides are infinite.
But of course they are not. And only when the value of protecting them, and in some cases replacing them, is calculated, does their vital role in the global economy become clear.
Some are obvious, for example the clean and accessible water that is needed to grow crops to eat, and the fish that provide one-sixth of the protein consumed by the human population.
But others are less so, for example the mangrove swamps and coral reefs that provide natural barriers against storms that devastate coastal regions; the vast array of plant species that provide pharmaceutical companies with endless genetic resources used for live-saving drugs; and the insects that provide essential pollination for growing around 70% of the world's most productive crops.
Bee collapse
It is a hugely complex process, but an economic value can be placed on these resources and services.
In the US in 2007, for example, the cost to farmers of a collapse in the number of bees was $15bn, according to the US Department of Agriculture, contributing to a global cost of pollination services of $190bn, according to Teeb.
Deforestation increases the risk of flooding in surrounding areas As Paven Sukhdev, a career banker and team leader of Teeb, says: "Bees don't send invoices".
Research by consultancy group PricewaterhouseCoopers also suggests the economic losses caused by the introduction of non-indigenous, agricultural pests in Australia, Brazil, India, South Africa, the US and the UK are more than $100bn a year.
In 1998, flash flooding in the Yangtze River in China killed more than 4,000 people, displaced millions more and caused damage estimated at $30bn. The Chinese government established that extensive logging in the region over the previous 50 years had removed the trees that provided essential protection from floods. It promptly banned logging.
Indeed the Centre for International Forestry Research has estimated that, in the 50 years prior to the ban, deforestation cost the Chinese economy around $12bn a year.
Business costs
The impact of biodiversity loss is felt hardest by the world's poor. The livelihood and employment of hundreds of millions of people depend upon the world's natural resources, whether it be fish to eat or sell, fertile soil for farming or trees for fuel, construction and flood control, to name just three.
As Mr Sukhdev explains: "Biodiversity is valuable for everyone, but it is an absolute necessity for the poor".
For example, Teeb has calculated that the Earth's natural resources and the services they provide contribute 75% of the total economic output of Indonesia, and almost half of India's output.
But it's not only the poor who suffer.
Businesses will increasingly be hit as they start paying for their part in biodiversity loss.
Not only will they have to pay to protect or replace services that nature has historically provided for free, but they will be forced to pay by regulatory instruments such as pollution taxes, like carbon credits and the landfill tax that already exist, and higher insurance premiums.
Increased flooding is partly due to land conversion by humans Then there is the cost of paying for the increased number of natural disasters, resulting in part from more extreme weather conditions caused by rising temperatures due to greenhouse gases, and even reputational damage among consumers that are becoming increasingly sensitive to environmental issues.
Trucost and PRI have estimated the cost of environmental damage caused by the world's largest 3,000 companies in 2008 at $2.15tn.
That equates to around one-third of their combined profits.
Again, these figures are only estimates, but the scale of the costs that will have to be paid by companies for their damage to the environment cannot be ignored.
cont.You don't have to be an environmentalist to care about protecting the... more
-
-
Today about 50 percent of the world's soils are subject to direct management by humans. But global soil change is also occurring in more remote areas due to the spread of contaminants and alterations in climate, Richter's report says.
Worldwide, soils are being transformed by human activities in ways that we poorly understand, with possibly dire implications.
"Properties and processes in the soil are more dynamic and susceptible to change than we previously thought," Richter said.
"Only recently are we documenting how [many aspects of soil chemistry and composition] are all highly responsive to human activities."
Rattan Lal, of Ohio State University in Columbus, is a past president of the Soil Science Society of America.
He said that severe soil degradation is increasing globally at a rate of 12.4 million to 24.7 million acres (5 million to 10 million hectares) annually.
In parts of Africa and Asia where the problem is most severe, soils are simply put to too many uses, Lal said.
"Crop residue is taken away for competing uses, animal dung is used as cooking fuel rather than as soil amendment, topsoil is used for brick making, and nutrients are harvested and not replaced," he said.
Such local impacts are causing global problems. Soil degradation plays much a larger role in climate change, for example, than was previously suspected.
That's because organic matter in soils store vast amounts of carbon—more than is present in the atmosphere and in all land vegetation combined.
But heavily cultivated and degraded soils lose their carbon-storing ability as exposed organic matter breaks down, noted geologist Bruce Wilkinson of Syracuse University in New York.
"Over the past half century or so, global soils have lost approximately a hundred billion tons of carbon [in the form of carbon dioxide] to the atmosphere through such exposure," said Wilkinson, who was not involved in Richter's study.
Recent studies by Wilkinson and others also show that humans are now the predominant geological force operating on the planet.
Rates of sedimentation and erosion caused by human activities—mainly agriculture—are ten times higher those attributable to natural processes.
And on agricultural land, he says, soil is being lost ten times faster than it is being replaced.
"Humans are rapidly consuming the global soil reservoir," Wilkinson said. "In light of the growing global population, this is obviously a very serious change."Today about 50 percent of the world's soils are subject to direct management by... more
-
-
Our human footprint doesn’t end after we buy and consume things; the final impact occurs when we discard items – and we Americans discard four-fifths of a ton of trash per person, per year.
At link:
-How to Create Less Trash
-Recycling Resources
-How to Reduce Your Carbon Footprint
--And more!Our human footprint doesn’t end after we buy and consume things; the final... more
-
-
"Atrazine provides a double whammy to frogs: It increases both amphibian exposure and susceptibility," says biologist Jason Rohr of the University of South Florida in Tampa, who tested the impact by re-creating field conditions in 300-gallon (1,135-liter) tanks in his lab. "Atrazine is one of the more mobile and persistent pesticides being widely applied. In fact, residues have been found in remote, nonagricultural areas, such as the poles."
That may explain why amphibians are on the decline worldwide. As many as one third of the nearly 6,000 known amphibian species—frogs, toads, salamanders, even wormlike caecilians—are threatened with extinction, according to the International Union for Conservation of Nature (IUCN). And no one knows why.
In the case of the northern leopards, the culprit appears to be the common herbicide acting as a double-edged sword: It suppresses the frogs' immune systems while boosting the population of snails that play host to parasitic worm larvae, the latter of which infect the weakened leopard frogs.
Such herbicides are present in 57 percent of U.S. streams, according to the U.S. Geological Survey, and it is that water pollution—not inbreeding—that is the prime suspect in the high rate of deformity in U.S. amphibian populations, according to new research from Purdue University.
But national parks and other areas protected from pollution and development are providing no refuge. The frogs and salamanders of Yellowstone National Park have been declining since the 1980s, according to a Stanford University study, as global warming dries out seasonal ponds, leaving dried salamander corpses in their wake. Since the 1970s, nearly 75 percent of the frogs and other amphibians of La Selva Biological Station in Braulio Carrillo National Park in the Caribbean lowlands of Costa Rica have died, perhaps due to global warming.
Throughout the tropics, amphibians are also falling prey to a devastating disease, believed to be exacerbated by climate change: chytrid fungus. This pathogen is marching though Central America at present, leaving silent streams—those without the chorus of dozens of frog species—behind. Researchers at the University of Georgia in Athens have surveyed such streams before, during and after such extinctions, and documented the impacts in those waters that have lost all of their amphibians, including muddier waters and a less productive food web.
"There are a whole lot of things that aren't being eaten, mostly insects," says biologist Joseph Mendelson of Zoo Atlanta. "And there are a whole lot of other creatures that don't have prey."
More at link!"Atrazine provides a double whammy to frogs: It increases both amphibian exposure... more
-
-
"Humanity's impact on climate has been detected on every continent except Antarctica, or so said the United Nations Intergovernmental Panel on Climate Change (IPCC) in February 2007. No longer: scientists, comparing decades of records from 17 Antarctic weather stations with computer simulations of Earth's climate, found that human-induced global warming has been heating up the continent that is home to the South Pole, as well.
"We have detected the human fingerprint in both the Arctic and Antarctic region[s]," says Peter Stott, a climate modeler at the U.K. Met (meteorological) Office's Hadley Center, and co-author of the study published in the journal Nature Geoscience.
The researchers compared 100 years of weather records from the Arctic and 50-plus years of those kept on Antarctica with the results of four computer models. Their findings: natural influences such as changes in the amount of sunlight or volcanic eruptions did not explain the warming trends, but the results matched when increasing levels of greenhouse gas emissions were added to the mix.
In the past few decades, average Arctic temperatures have warmed roughly 3.6 degrees Fahrenheit (2 degrees Celsius); average temperatures in Antarctica have warmed slightly less than 1.8 degrees Fahrenheit (1 degree Celsius).
Lead study author Nathan Gillett, a climatologist at Environment Canada, the government ministry charged with Canadian environmental protection and issues, notes that the collapse of the Larsen B and Wilkins ice shelves on the Antarctic Peninsula, which has warmed more than any other part of the entire world, has already been linked to global warming.
As if the new finding is not disturbing enough, researchers may have underestimated the temperature change because they gave equal weight to readings from the cold continental interior—where another man-made problem, the ozone hole, has contributed to cooling in the spring and summer—and coastal regions, where warming is more pronounced.
"These areas are most susceptible to climate warming in the coming century in Antarctica, because they are the closest to the melt threshold," says climatologist Andrew Monaghan of the National Center for Atmospheric Research in Boulder, Colo., who was not involved in this study but reviewed the research.
After all, it is those areas that are closest to the melting point that can tip precipitously—as did Arctic Ocean sea ice in recent years. "One quarter to one half of the Antarctic coastline has some substantial warming going on as of now," Monaghan adds.
All told, if the eastern and western Antarctic ice shelves were to melt completely, they would raise sea levels by as much as 230 feet (70 meters); the collapse of smaller shelves like Larsen B has sped up the flow of glaciers behind them into the sea, contributing to the creeping up of high tide levels around the world. And that's likely to get worse before it gets better.
"There will be continued residual warming no matter what greenhouse gas reductions we make," Monaghan warns. "We really need to pay closer attention to what is going on with this ice sheet.""Humanity's impact on climate has been detected on every continent except... more
-
