Earth More Sensitive to Carbon Dioxide Than Previously Thought

The temperature response of the Earth (in degrees C) to an increase in atmospheric carbon dioxide from pre-industrial levels (280 parts per million by volume) to higher levels (400 parts per million by volume). (a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model (b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice). (Credit: Image courtesy of University of Bristol)

ScienceDaily — In the long term, the Earth's temperature may be 30-50% more sensitive to atmospheric carbon dioxide than has previously been estimated, reports a new study published in Nature Geoscience.

The results show that components of the Earth's climate system that vary over long timescales -- such as land-ice and vegetation -- have an important effect on this temperature sensitivity, but these factors are often neglected in current climate models.

Dan Lunt, from the University of Bristol, and colleagues compared results from a global climate model to temperature reconstructions of the Earth's environment three million years ago when global temperatures and carbon dioxide concentrations were relatively high. The temperature reconstructions were derived using data from three million-year-old sediments on the ocean floor.

Lunt said, "We found that, given the concentrations of carbon dioxide prevailing three million years ago, the model originally predicted a significantly smaller temperature increase than that indicated by the reconstructions. This led us to review what was missing from the model."

The authors demonstrate that the increased temperatures indicated by the reconstructions can be explained if factors that vary over long timescales, such as land-ice and vegetation, are included in the model. This is primarily because changes in vegetation and ice lead to more sunlight being absorbed, which in turn increases warming.

Including these long-term processes in the model resulted in an increased temperature response of the Earth to carbon dioxide, indicating that the Earth's temperature is more sensitive to carbon dioxide than previously recognised. Climate models used by bodies such as the Intergovernmental Panel on Climate Change often do not fully include these long-term processes, thus these models do not entirely represent the sensitivity of the Earth's temperature to carbon dioxide.

Alan Haywood, a co-author on the study from the University of Leeds, said "If we want to avoid dangerous climate change, this high sensitivity of the Earth to carbon dioxide should be taken into account when defining targets for the long-term stabilisation of atmospheric greenhouse-gas concentrations."

Lunt added: "This study has shown that studying past climates can provide important insights into how the Earth might change in the future."

(a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model

(b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice).

This research was funded by the Research Council UK and the British Antarctic Survey.

Souce: http://www.sciencedaily.com/releases/2009/12/091206162955.htm

Marine Reserves Can Be An Effective Tool For Managing Fisheries

Monitoring of marine protected areas ranges from scuba surveys of fish to intertidal surveys of invertebrates and algae. (Credit: Photos by Robert Schwemmer/NOAA)

ScienceDaily — Studies conducted in California and elsewhere provide support for the use of marine reserves as a tool for managing fisheries and protecting marine habitats, according to biologists at the University of California, Santa Cruz.

A recent study in the Gulf of California, for example, confirmed the validity of a key concept behind marine reserves--the idea that offspring produced in a protected area can replenish the stocks of harvested species outside the reserve.

"It seems really obvious, but it had never been tested," said Peter Raimondi, professor and chair of ecology and evolutionary biology at UCSC and coauthor of a paper describing the findings in the journal PLoS One.

"We created a model to predict the dispersal of larvae outside the reserves, and the results were completely consistent with our predictions," he said.

Raimondi is involved in a collaborative project (called PANGAS) in which researchers are working with Mexican fishing communities to study and manage fisheries in the northern Gulf of California. Local fishermen in the area of Puerto Peñasco set up a network of marine reserves as part of a community-based effort to manage their resources. Ecological and social studies conducted before, during, and after the establishment of those reserves enabled the researchers to track the results.

Raimondi emphasized that resource managers have a wide range of tools at their disposal and must take into account both biological and social factors in choosing the best approach. Many species, such as tuna and squid, move around too much to be protected by setting aside certain areas. For species that tend to stay put, marine protected areas can range from no-take reserves to various levels of limited harvesting, and sometimes involve restrictions on who can harvest fish in an area rather than how much can be taken.

The establishment of marine protected areas along the California coast, as called for in the 1999 Marine Life Protection Act (MLPA), has been controversial. A network of protected areas was established on the Central Coast in 2006, and a plan for the North-Central Coast was adopted in August 2009. In Southern California, a task force will soon make recommendations to the state Fish and Game Commission, while on the North Coast the planning process is just getting started.

Raimondi and Mark Carr, also a professor of ecology and evolutionary biology at UCSC, have been actively involved in this initiative. In addition to serving on science advisory teams, they are engaged in an intensive monitoring program to track the effects of the reserves that have already been established.

"We are monitoring those areas at unprecedented levels. It's a comprehensive effort to characterize the populations and the ecosystems so that we can compare the responses to different types of protection," Carr said. "Monitoring studies around the globe systematically show positive responses within protected areas. We want to really identify what aspects of reserve design are important in influencing those benefits."

According to Carr, it will take a few more years of monitoring to see the effects of the Central Coast reserves. In the Channel Islands, however, where reserves were established in 2003 (separately from the MLPA process), surveys have yielded the kinds of results scientists expect to see in protected areas. For example, fish species targeted by fishermen tend to be bigger and more plentiful within the reserves.

This effect is important, because studies have shown that larger, older females are much more important than younger fish in maintaining healthy populations of species such as West Coast rockfish.

"When you have a protected population, you not only get spillover effects when fish swim out of the reserve and get caught, you also have major effects on larval production," Carr said. "The bigger, older fish in the reserve produce a lot of larvae that replenish the fished populations outside."

Carr, who contributed to a report on the first five years of monitoring in the Channel Islands, said that the conclusions are limited by a lack of data collected before the reserves were created. It is possible that some of the observed differences existed before the areas were protected, but such doubts will be erased if current population trends continue, he said.

In Puerto Peñasco, the shellfish harvested by local fishermen grow and reproduce quickly. As a result, the fishermen saw beneficial effects within a year after they had established a network of reserves. Subsequent events, however, underscored the role of social factors in the success of fishery management efforts. A second paper, published in PLoS ONE in July, describes how, after its initial success, the local reserve system collapsed due to poaching by outsiders.

"The whole thing got wiped out due to disruption of the social structure that had supported it," Raimondi said. "Scientifically it was really interesting, but for the people who experienced it on the ground, it was terrible."

Richard Cudney-Bueno, a research associate at UCSC's Institute of Marine Sciences and cofounder of the PANGAS project, is the lead author of both papers. "Here was a group of fishermen that had already seen some declines in the shellfish they harvested. This led to the implementation of community-based efforts to manage their resources, including the establishment of marine reserves," he said. "We found that local control of community resources can work, but there has to be broader government support to back up the local efforts."

A native of Mexico City, Cudney-Bueno has been working with Mexican fishing communities and conducting ecological and social research in the Gulf of California since the mid-1990s. He now has a joint position with UCSC, the University of Arizona, and the David and Lucile Packard Foundation.

The first reserve in the Puerto Peñasco area was established in 2001 around an island. Cudney-Bueno and other researchers, working with a Mexican nonprofit organization (Centro Intercultural de Estudios de Desiertos y Océanos), trained the fishermen to monitor shellfish populations in and around the reserve. "The response was really quick, so they could see a classic reserve effect one year later," Cudney-Bueno said. "That led to more areas being closed, and the first paper shows the effects of the network of reserves."

The cooperative was so successful it was recognized by the Mexican government with a Presidential Conservation Award. But word spread quickly along the coast about the thriving shellfish populations in Puerto Peñasco, and other fishermen from outside the community began to move in and poach from the reserves. After poaching began, the system of cooperation that had established and protected the reserves broke down.

Now, the situation is beginning to improve again, Cudney-Bueno said. The Mexican government has created one of a handful of exclusive fishing zones in the Gulf of California, giving the local cooperative the exclusive legal right to harvest shellfish in the Puerto Peñasco area.

"They now have a strong management plan with legal rights and government support, so I think they will be able to get back to where they were before the poaching started," Cudney-Bueno said. "I see it as part of the evolution of a management system. Social change takes time, and it really hasn't been that long. A lot is happening now in Mexico and around the world as local people are increasingly asking for control over their resources. Various fishing communities in Mexico, including lobster and abalone fishermen in Baja California, have moved forward with the establishment of their own marine reserves and government-backed forms of territorial-use rights."

The PANGAS project, which brings together experts from UCSC, the University of Arizona, and several collaborating academic institutions and nonprofit organizations in Mexico, is working with other fishing communities in the Gulf of California to develop management plans for the region's marine resources.

"PANGAS is now working with the Mexican government to build management plans for a series of species in the northern Gulf of California," Raimondi said. "It's interesting to compare that with the MLPA process in California. The approaches are very different, and it has to do with differences in government and social structures."

According to Carr, the California MLPA process is now being used as a model in other parts of the world, most notably in the United Kingdom.

Souce: http://www.sciencedaily.com/releases/2009/11/091109142129.htm

Florida considers protection for lemon sharks

Lemon sharks are being considered for protection. (Walt Stearns, Florida Fish and Wildlife Conservation Commission / November 19, 2009)

Undersea predators called vital to health of reefs
By David Fleshler, Sun Sentinel

They are the lords of the reefs, powerful 10-foot sharks that prowl shallow coastal waters, snatching stingrays, crabs and mullet.

But while lemon sharks can hold their own in the undersea jungle, they face a tougher time against the predators equipped with powerboats, baited hooks and satellite tracking devices.

The Florida Fish and Wildlife Conservation Commission this month is considering a ban on the catch of lemon sharks, hoping to protect a species that plays an important role in maintaining the health of coral reefs.

The proposal for the ban came from a group of scientists and environmentalists clustered around University of Miami professor Samuel Gruber, the world's foremost lemon shark expert. They fear that restrictions on catching other shark species over the past couple of years are leading fishermen to turn their attention to lemon sharks. Since 2004, the Florida lemon shark catch has risen more than 400 percent.

Because these sharks take years to mature and bear few young, they have difficulty recovering from heavy fishing pressure. In the 1980s in the Florida Keys, for example, where Gruber was tagging sharks, the entire population had virtually disappeared by 1986.

"It was targeted by commercial fishermen," he said. "They set huge gill nets and everything they caught went to the fish house for 10 cents a pound."

Adding to the lemon shark's vulnerability is the species' bizarre habit of assembling in large, stationary groups on the ocean floor. A couple of miles off Jupiter, for example, lies the biggest known aggregation of lemon sharks, with groups of up to 100 visible during the winter.

"They're lying on the sand, nose into the current, basically shoulder to shoulder like cars in a parking lot," said Walt Stearns, a professional undersea photographer from Palm Beach Gardens, who brought the assemblage of sharks to the attention of scientists.

Gruber describes this as the largest known congregation of lemon sharks on the East Coast of the United States, and he said it highlights the danger to the sharks from people.

"They could target and catch them and wipe them out in a matter of weeks," Gruber said.

Fort Pierce shark fisherman Joe Klosterman takes his 37-foot boat Gale Mist II up to 25 miles out to sea, where he deploys a longline baited with mullet, bluefish and bits of shark. He says he hasn't noticed a decline in lemon sharks and that a catch ban won't do the sharks much good.

Although he would be required to throw back any banned sharks he catches, he said that doing so will do little for the shark since at that point it would probably be dead.

"Some sharks die real quick on the lines," he said. And throwing one back would cost him the $300 or so he could have earned for the shark's fins alone, which are exported to East Asia for shark fin soup, a delicacy.

"Most fisherman are all for conservation," he said. "You want to see a sustainable fishery. But I don't see where this is going to save more sharks."

Lemon sharks, named for their yellow-brown color, live in coastal waters from the mid-Atlantic states to southern Brazil. They rank 13th in attacks on people, far below the "big three" for shark attacks: the great white, tiger and bull sharks, according to the International Shark Attack File at the Florida Museum of Natural History. There have been no known fatal attacks by lemon sharks.

The sharks play an important role in maintaining the health of shallow ecosystems, such as coral reefs, by preventing lesser predators from multiplying out of control, Gruber said. They hold down the population of stingrays, for example. Without this service, the stingrays would devastate the lobsters, with further consequences down the food chain.

"The lemon shark is one of the largest predators on the reef," Gruber said. "If you were to take away the predator pressure, you will cause an ecological disruption in the balance of species."

The wildlife commission will decide whether to approve a draft ban on lemon shark catches at its Dec. 10 meeting in Clewiston.

The commission's ban would apply only to state waters, which extend three miles off the east coast and nine miles off the west coast. But the federal government, which regulates fishing up to 200 miles off the coast — except where that zone would run into the Bahamas — may follow Florida's lead if the state requests it. Karyl Brewster-Geisz, fishery management specialist for the National Marine Fisheries Service, said states normally request comparable regulations in federal waters for consistency.

Staci-lee Sherwood, a Lighthouse Point animal rights activist who filed comments with the commission in support of the ban, said lemon sharks have far greater economic value if they remain in place to be seen by dive boats full of tourists, rather than killed for a few hundred dollars worth of fins and meat. But beyond that, she said, they have value beyond any use by human beings.

"I'm against any kind of cruelty to animals," she said. "I wouldn't justify killing any animal just for its fins or ivory or fur."

David Fleshler can be reached at dfleshler@SunSentinel.com 954-356-4535.

Source: http://www.sun-sentinel.com/news/local/florida/fl-lemon-shark-20091203,0,3793198,full.story