Led by Florida Museum of Natural History vertebrate paleontologist Larisa DeSantis, researchers examined fossil teeth from mammals at two sites representing different climates in Florida: a glacial period about 1.9 million years ago and a warmer, interglacial period about 1.3 million years ago. The researchers found that interglacial warming resulted in dramatic changes to the diets of animal groups at both sites. The study appears in the June 3 issue of PLoS ONE.

“When people are modeling future mammal distributions, they’re assuming that the niches of mammals today are going to be the same in the future,” DeSantis said. “That’s a huge assumption.”

Co-author Robert Feranec, curator of vertebrate paleontology at the New York State Museum, said scientists cannot predict what species will do based on their current ecology.

“The study definitively shows that climate change has an effect on ecosystems and mammals, and that the responses are much more complex than we might think,” Feranec said.

The two sites in the study, both on Florida’s Gulf Coast, have been excavated quite extensively, DeSantis said. During glacial periods, lower sea levels nearly doubled Florida’s width, compared with interglacial periods. But because of Florida’s low latitude, no ice sheets were present during the glacial period. Despite the lack of glaciers in Florida, the two sites show dramatic ecological changes occurred between the two periods.

Both sites include some of the same animal groups, allowing DeSantis, Feranec and Bruce MacFadden, Florida Museum curator of vertebrate paleontology, to clarify how mammals and their environments responded to interglacial warming.

The research examined carbon and oxygen isotopes within tooth enamel to understand the diets of medium to large mammals, including pronghorn, deer, llamas, peccaries, tapirs, horses, mastodons, mammoths and gomphotheres, a group of extinct elephant-like animals.

Differences in how plants photosynthesize give them distinct carbon isotope ratios. For example, trees and shrubs process carbon dioxide differently than warm-season grasses, resulting in different carbon isotope ratios. These differences are incorporated in mammalian tooth enamel, allowing scientists to determine the diets of fossil mammals. Lower ratio values suggest a browsing diet (trees and shrubs) while a higher ratio suggests a grazing diet (grasses).

Animals at the glacial site were predominantly browsing on trees and shrubs, while some of those same animals at the warmer interglacial site became mixed feeders that also grazed on grasses. Increased consumption of grasses by mixed feeders and elephant-like mammals indicates Florida’s grasslands likely expanded during interglacial periods.

Tooth enamel locks in the chemical signatures of the plants and water an animal consumes, allowing paleontologists to understand the diets and associated climate of fossil specimens that are millions of years old. To find these signatures, researchers run samples of tooth enamel through a mass spectrometer.

DeSantis and her collaborators analyzed enamel samples from 115 fossil teeth. For two of the specimens she took serial samples, small samples that run perpendicular to the growth axis and give insight into how the diet and climate changed over a specific period of time.

“That’s one of the cool things about using mammal teeth,” she said. “We can actually look at how variable the climate was within a year, millions of years ago.”

The study highlights the importance of the fossil record in understanding long-term ecological responses to changes over time, DeSantis said. While ecological studies of modern impacts can cover only limited spans of time, “this study emphasizes the importance of using the fossil record to look at how mammals and other animals responded to climate change in the past, also helping us gain a better understanding of how they might respond in the future.”

At the same time, plants will proliferate, nurtured by balmier temperatures, more nutrients from decomposing soil and the increasing abundance of the greenhouse gas they depend on for growth.

These connected but contrasting changes have raised a question for scientists who study the causes and consequences of global climate change: Will the shrubs and incipient forests spreading across the Arctic compensate for the permafrost’s rising release of carbon, blunting its impact on a warming planet? Or, with twice as much carbon locked up in the permafrost as now present in the atmosphere, will the lush growth become overwhelmed — like a kitchen sponge put down to stem a water main break?

Researchers led by a University of Florida ecologist may have an answer. In a paper set to appear May 28 in the journal Nature, the team reports experimental results suggesting tundra plant growth may keep up with rising carbon dioxide initially.

But if thawing continues in a warmer world, the permafrost will spew carbon for decades, and the plants will become overwhelmed — unable to sop up the excess carbon despite even the most vigorous growth.

“At first, with the plants offsetting the carbon dioxide, it will appear that everything is fine, but actually this conceals the initial destabilization of permafrost carbon,” said Ted Schuur, a UF associate professor of ecology and lead author of the paper. “But it doesn’t last, because there is so much carbon in the permafrost that eventually the plants can’t keep up.”

Schuur noted most of the 13 million square kilometers, or roughly 5 million square miles, of permafrost in Alaska, Canada, Siberia and parts of Europe remain frozen. However, thawing already occurring around its southern edges is expected to expand this century.

Should that occur, this study suggests the permafrost could lose in the range of 1 gigaton of carbon, or 1 billion tons, per year – about the same order of magnitude as being added by current deforestation of the tropics, another large biospheric source, Schuur said.

While burning fossil fuels contributes considerably more carbon, about 8.5 gigatons annually, that process can at least in theory be controlled – whereas once the permafrost thaw begins, it sets up a self-reinforcing loop far from human activity and potentially difficult to stop.

That highlights the urgent need to address human-caused emissions now, Schuur said.

“It is not an option to be putting insulation on top of the tundra,” he said. “If we address our own emissions, either by reducing deforestation or controlling emissions from fossil fuels, that’s the key to minimizing the changes in the permafrost carbon pool.”

Researchers from UF used hand-built, automated chambers to trap and measure carbon dioxide losses in Alaska year-round from 2004 through 2006. Thawing at the research sites near Denali National Park, in central Alaska, varies considerably, with some plots much more extensively thawed than others.

The researchers determined how long each spot had been thawing using long-term data from permafrost-monitoring instruments combined with historical aerial photographs. With a total of 18 of the automated chambers, they measured the release and uptake of carbon between the tundra and the atmosphere. This resulted in a measurement of net ecosystem carbon exchange – the total carbon each spot lost, or gained, due to thawing permafrost.

The results were clear.

Tundra sites that had thawed for the past 15 years gained net carbon, as increasingly verdant plant growth was greater than the permafrost’s carbon losses. However, radiocarbon dating of carbon dioxide showed that old carbon from the permafrost was already being released in higher amounts due to thaw – signifying that all was not well with the permafrost carbon even in that time period. The site that began thawing decades before gained net carbon emission to the atmosphere, revealing that more thaw caused significantly more old carbon loss — despite greening of the vegetation, including more shrubs.

Said Jason Vogel, a UF postdoctoral associate and author of the paper: “The plants are still growing faster in the extensively thawed area, but that’s not enough to keep up with the greater microbial activity releasing old carbon from deeper in the soil.”

As a result, even as the Arctic greens, its escalating old carbon loss “could make permafrost a large biospheric carbon source in a warmer world,” according to the paper.

The other authors are Kathryn Crummer, a UF lab technician; Hanna Lee, a UF doctoral student; James Sickman, of the University of California, Riverside; and T.E. Osterkamp of the University of Alaska, Fairbanks. The research was funded by the National Science Foundation, NASA and a cooperative agreement with the National Park Service.

“I don’t fight them anymore,” says Anderson, the college’s director of facilities operations. “It was a no-win situation for us.”

It’s a common story, says Michael Avery, a U.S. Department of Agriculture wildlife biologist affiliated with the University of Florida’s Institute of Food and Agricultural Sciences.

Avery is one of the nation’s top vulture management experts. He and U.S. Geological Survey and U.S. Fish and Wildlife Service colleagues just published a paper on a mathematical formula that can help determine how many vultures can be taken from a local population without jeopardizing its long-term viability. The article is in May’s issue of The Journal of Wildlife Management.

Though they perform a vital function by eating dead animals, vultures can create problems when they co-exist with people, something that’s happened more in recent decades as both populations have grown.

The birds habitually peck at soft objects, so in residential areas they destroy vinyl cushions and rubber seals around car doors and windows. When they roost on utility poles and cell phone towers, their waste makes climbing surfaces slippery. Sometimes flying vultures collide with aircraft, endangering pilots and passengers.

For Anderson, the birds were mainly an annoyance. They ripped up roof expansion joints and pipe insulation; occasionally they entered ventilation ducts and died, which caused odors in classrooms and left workers to disassemble exhaust systems and retrieve the bodies.

He tried several popular methods to chase them off — effigies, electrified wires and motion-activated sprinklers. The sprinklers irritated the vultures enough that they left, settling on another campus building. That’s when Anderson decided it was easier to live with the birds.

Killing nuisance vultures is a last resort, and is rarely used. Although it can drive a flock away in short order, lethal control is not a permanent solution, Avery says. Vultures are protected by federal law. Lethal control requires a U.S. Fish and Wildlife Service permit.

“When they issue permits USFWS need some assurance they’re not taking too many birds,” he said. “That’s when the question of how many birds are out there becomes relevant.”

Called Prescribed Take Level, the formula includes the size of the animal population, its maximum growth rate, and a variable determined by wildlife managers, based on how much they need to reduce population size.

The current study used the black vulture population in Virginia as a case study. Black vultures and turkey vultures are the dominant U.S. vulture species.

Precisely estimating local vulture populations is difficult, due to uncertainties about their lifespan and breeding habits. The researchers relied on annual bird-count data and studies of radio-tagged vultures.

Still, team members are confident they’ve gathered enough data to show the mathematical model can work, Avery says. He points out the study isn’t meant to advocate lethal control.

“Some people think there are too many vultures. Are there? I don’t know,” he says. “That’s more of a policy question, that’s not something we delve into.”

Michael Runge, a Maryland-based U.S. Geological Survey research ecologist and another author of the study, agrees. An objective permitting process will only improve inter-agency relations, he said.

Ranchers who lose livestock to black vultures will welcome the study, said Paul Rodgers, deputy policy director for the American Sheep Industry Association in Englewood, Co. The birds kill newborn lambs, sometimes attacking them as they’re born, he said.

“We certainly need a certain number of vultures,” Rodgers said. “But any population of any animal can get out of hand. And it seems like black vulture populations are getting out of hand in some areas.”

It’s been about five years since the southeastern U.S. saw a good termite swarm season like those that were once common, University of Florida researchers say. Swarms of termites fly from their nests to mate and start new colonies.

In the last few years, termites have swarmed maybe two or three days, but nothing like the frequent, repeated swarms that used to occur, said Phil Koehler, an urban entomology professor with UF’s Institute of Food and Agricultural Sciences.

Koehler believes he knows why swarms are scarce. Pest control operators have begun to see wingless, crawling termites. Termites don’t need to fly to mate, so rather than swarming, they’re crawling off by the thousands to form new colonies, he said.

That means homeowners and even pest control experts can miss these events, because no telltale wings are left behind. And without evidence of infestation, homeowners may not get the warning they need.

“It’s like having a smoke alarm without a battery in it,” Koehler said. “If you have termites right now, you could have significant damage and not have any sign of it.”

Floridians deal with two main types of termites: subterranean termites, which tunnel from moist underground places and attack homes from the ground up; and drywood termites, which are found in the dry wood of the house. Both species can go undetected until they’ve done extensive damage to a home.

Typically, subterranean termites swarm from January until about April while their drywood counterparts have a peak swarming time in June and July.

Koehler and research associate scientist Roberto Pereira believe two factors have kept termite swarms to a minimum: better pest control methods and drought conditions in the southeastern U.S.

Despite recent heavy rains and even flooding in some areas, much of Florida remains under severe drought conditions, according to IFAS’ Southeast Climate Consortium.

When deprived of water, subterranean termites stay underground searching for it, Koehler said, which is why he believes the drought is at least partly to blame for the dearth of swarms. Koehler and Pereira theorize that drought conditions have forced termites underground for so long that by the time they emerge, they’ve lost their wings.

If limited swarming continues, it would underscore the need for homeowners to seek professional termite treatment, he said.

The state’s building codes were strengthened in 2001 to require that new construction include termite protection. In 2004, the state mandated that builders choose termite-protection products from a list of 64 proven effective in Florida.

Even with those rules, about half of Florida’s homeowners have no termite protection, Koehler said.

“It’s pretty cheap to prevent termites, but expensive if you get them,” Pereira said.

Florida Pest Control President D.R. Sapp Jr., whose company’s 20 offices cover much of Florida, said he agrees with researchers’ theories about better controls and climate.

“It used to be when termites started swarming, our phones would ring off the hook,” he said. “But termites haven’t left, they’re still here. They just don’t rear their heads and make their presence known as they did in the past.”

According to the annual Florida Land Value Survey, conducted by the University of Florida’s Institute of Food and Agricultural Sciences, rural land and land outside of metropolitan areas — eagerly sought by developers in recent years — is now commonly being offered for sale at a fraction of its cost.

“In some cases, it’s almost like a fire sale,” said Rodney Clouser, the UF professor of food and resource economics who led the survey. Some respondents reported large blocks of land being offered at 20 to 30 percent of their purchase price.

A population boom between 2002 and 2006 contributed to a dramatic rise in land prices throughout Florida. But now, the state’s annual population increase is expected to be only 10 percent of the boom years’ growth, according to UF population projections.

The survey, which does not cover urban land values, showed that land outside of cities primed for development, dubbed transition land, decreased by as much as 55 percent in the northern half of the state.

Transition land within five miles of urban centers in the southern half of the state lost nearly 40 percent of its value.

However, in the one exception to the otherwise gloomy economic picture, transition land more than five miles away from urban centers in the southern half of the state increased by 5 percent. Most likely, this is because its low price and relative location to large cities was seen as the best deal by those still looking to buy real estate, Clouser said.

Nevertheless, the 5 percent increase is significantly smaller than the nearly 17 percent increase for the same area last year.

Lagging development hasn’t just affected areas destined for shopping malls and homes. It has also contributed to drops as large as 26 percent in farmland values.

Although such land is typically evaluated primarily by the profitability of the crop produced, urban expansion was so rapid in recent boom years that many began to evaluate the land based on what it would bring if used for housing or other development purposes, Clouser said.

Land prices are expected to continue their drop through 2009 — although not as dramatically as in 2008. Survey responses from individuals involved in the Florida real estate market predict an overall drop between 5 and 17 percent.

Even after the national economic picture brightens, Clouser said, a surplus of homes and other existing development would need to be sold before demand would once again drive land prices up.

The report can be viewed at http://edis.ifas.ufl.edu/FE798.

No, really — actual dirt. Spodosols, Histosols, Ultisols, you name it, they’ve dug them up, labeled them and ferried them back to their lab at the University of Florida’s Institute of Food and Agricultural Sciences, where they’re being analyzed for associate professor Sabine Grunwald as part of the state’s largest-ever soil-carbon study.

When completed next year, the study could help Florida venture into the carbon-credit market, a way for governments, farmers and landowners to earn money while helping reduce greenhouse gases by storing carbon in soils.

Grunwald’s study, a USDA-funded, three-year core project of the North American Carbon Program, is nothing if not audacious: The soil and water science expert has charged her team with collecting a total of 1,000 soil samples from just about every conceivable type of land in Florida.

Their goal is to create a comprehensive soil carbon inventory for the state, and be able to predict — based on factors such as land use, hydrology and topography — how much carbon can be stored in the ground.

While it’s already established that Florida has more soil carbon than any other state, officials here haven’t yet taken advantage of that by jumping into carbon-credit markets.

Carbon-credit markets seek to mitigate global warming by allowing the market to assign a dollar value to measurable reductions of harmful greenhouse gases and allowing “credits” for such reductions to be bought and sold. In some cases, farm land would need to be left untilled for several seasons to allow carbon to be stored.

Those markets are far more active in Europe than the U.S., though many expect such markets here to become more viable and lucrative in the not-too-distant future.

But what landowners and those who make decisions about land use need to know before taking the plunge is how much carbon is stored in different types of soil.

“What we really need first is accurate data,” Grunwald said. “And what we researchers can contribute is knowledge about how carbon is sequestered.”

A study Grunwald and her team conducted from 2005 until 2008 looked at soil carbon levels in the Santa Fe River watershed and allowed researchers to become adept at using soil spectroscopy, a cost-effective method that allows them to quickly make soil property inferences.

During that study, she said, it occurred to researchers that expanding their scope from the eight-county watershed to a statewide project only made sense.

“We just said, ‘let’s do it for the whole state,’” she said.

Bags full of soil samples and paper grocery sacks full of “litter” — things like dried grass and decomposed leaves the women scrape off the top of the earth right near where they auger the dirt samples, are starting to be analyzed.

Grunwald said she hopes the soil and litter analyses will be complete by late fall.

The project’s conclusion marks the end of months of grueling work by field team leader Aja Stoppe and helpers Lisa Stanley and Elena Azuaje, who have traversed thousands of miles across Florida, through swamp, pine forests, farm land, pastures and muck.

Their stories of weird looks from strangers and being covered in grime from ear to elbow are entertaining — like the time Stoppe stepped out onto what she thought was solid ground only to plunge into waist-deep water.

Driving back to Gainesville after a day spent collecting samples in the Osceola National Forest, they rehash exploits and marvel at the kindness of strangers.

And there, Stoppe points out a critical difference in having an all-female crew.

“We always send thank you cards to the people who helped us,” she said.

Other members of the team included graduate students Gustavo Vasques and Jongsung Kim, postdoctoral researchers Brent Myers and Deoyani Sarkhot, and UF faculty members Nick Comerford, Willie Harris and Greg Bruland.

A UF study, published online this week in the journal Plant, Cell and Environment, showed that when mouse-ear cress plants with the added gene were grown in arsenic-laden soil, their leaves contained as little as one-seventh the arsenic of control plants.

The study raises hopes that UF researchers can get similar results by putting the gene into rice plants, said Bala Rathinasabapathi, an associate professor with UF’s Institute of Food and Agricultural Sciences and co-author of the paper. If so, it could lead to new varieties for countries such as China and Bangladesh, where rice is a staple and the grain often absorbs arsenic from soil and water.

“In rice, it’s a very important problem,” he said.

Rice is the only crop plant that accumulates arsenic to a notable degree, said Rathinasabapathi, of the horticultural sciences department. When consumed even in small amounts over time, the toxic heavy metal increases cancer risk.

Arsenic has been used in pesticides, herbicides and wood preservatives. In some areas, residual arsenic from these products contaminates soil. In others, naturally occurring arsenic contaminates drinking and irrigation water used by millions.

The brake fern probably has many genes that allow it to absorb arsenic and survive, Rathinasabapathi said. So far, UF researchers have pinpointed one, a gene involved in production of glutaredoxin, a protein that helps plants deal with environmental stress.

This study was the first attempt to put that gene into another plant, he said. It was partly funded by an IFAS Research Innovation Award Rathinasabapathi received, amounting to about $12,500.

Other authors of the paper were Sabarinath Sundaram, a former UF postdoctoral associate now with Texas A&M University; Shan Wu, a UF biological scientist; and Lena Ma, a professor with UF’s soil and water science department.

Rathinasabapathi isn’t sure why the gene prevented cress plants from accumulating arsenic.

“Ferns are generally not very well investigated, genetically,” he said. “There may be many genes in the brake fern that will help with stress tolerance and may be helpful in improving crops, that is the overarching theme to my research program.”

The UF study is an interesting step, but there are challenges in producing viable low-arsenic rice varieties, said Andrew Meharg, biogeochemistry chair with the University of Aberdeen’s School of Biological Sciences in Scotland.

The mechanisms that control the arsenic content of rice grain are poorly understood, he said. If transgenic varieties were developed, they would need to outperform existing varieties in arsenic resistance and grain yield.

Meharg, an internationally known arsenic-contamination authority, analyzed white rice samples from 10 countries. He determined that residents of Bangladesh and China were at the most risk, based on the arsenic content and the amount eaten.

Computer-assisted genetic analysis could change that, say University of Florida scientists who have completed a demonstration study of a new method. It was published online this month in the journal Molecular Ecology Resources.

The method, known as massively parallel sequencing, reveals small parts of the DNA code for multiple nematodes simultaneously, said Dorota Porazinska, a courtesy assistant professor with UF’s Fort Lauderdale Research and Education Center. It can do the same for other invertebrates that live alongside nematodes, including bacteria, fungi and mites.

There may be more than 1 million nematode species, but only about 20,000 have been formally described. Nematodes live in almost every environment on Earth. Some species are parasites that prey on plants, animals or people.

By providing “who’s who” information on micro-organisms in crop fields, lawns and golf courses, the method may help explain why harmful nematodes attack plants in some sites but not others. It could also provide clues on how to keep sites healthy.

“We often look at agricultural systems only in terms of the organisms we think are bad,” said Porazinska, the study’s lead author. “But we skip over what’s being done by other organisms that don’t bother us. And they may be doing things to assist in the system.”

Once scientists know which micro-organisms live in a plot of land, they can begin manipulating variables and developing agricultural practices that discourage pest species, said Robin Giblin-Davis, a professor at the Fort Lauderdale center and another author.

In the study, UF researchers took a new approach to an instrument called a genome sequencer, commonly used to sequence the DNA structure of a single organism. Here, they sequenced small bits of DNA from samples taken from an artificially assembled community of known nematodes. Then they checked the results against DNA databases used to identify nematodes.

The study showed massively parallel sequencing identified nematode species with a high degree of accuracy. But it didn’t perform as well at determining how many individual nematodes the samples contained. So the researchers are working to refine their approach.

When massively parallel sequencing is used in the field, any nematodes that don’t match known species can be isolated for further study, Giblin-Davis said.

Previously, researchers identified nematodes one at a time — an approach that worked but was painfully slow, because genetic and morphological analysis was often required to confirm the species.

“With the traditional method, in two years we identified 360 nematodes from a tropical rainforest and now we can get thousands,” Giblin-Davis said. “This will give us a good chance, hopefully, of not only recovering what’s there commonly, but the rare things.”

The UF approach is an exciting development for scientists studying nematode populations, said Paul De Ley, an assistant professor with the University of California, Riverside.

“This is an approach that is likely to be adopted in the U.S., Western Europe and some Asian countries,” said De Ley, who researches nematode genetics. “The major limiting factor is that these kinds of sequencers are not widely available yet.”

Because the technology is costly, it may be difficult to employ in tropical regions where crop plants are often attacked by nematodes, he said. However, if government officials streamline current import policies, researchers may be able to easily transport soil samples from tropical regions to laboratories in industrialized nations, solving the problem.

GAINESVILLE, Fla. — The recession may be responsible for a slump of a different sort: an unexpected dive in shark attacks, says a University of Florida researcher.

Shark attacks worldwide in 2008 dipped to their lowest level in five years, a sign that Americans may be forgoing vacation trips to the beach, said George Burgess, ichthyologist and director of the International Shark Attack File, which is housed at UF.

According to the latest statistics released today, the total number of shark attacks declined from 71 in 2007 to 59 in 2008, the fewest since 2003, when there were 57, said Burgess, who works at the Florida Museum of Natural History on the UF campus.

“I can’t help but think that contributing to that reduction may have been the reticence of some people to take holidays and go to the beach for economic reasons,” Burgess said. “We noticed similar declines during the recession that followed the events of 2001, despite the fact that human populations continued to rise.”

Shark attacks dropped in the United States and abroad in 2008, Burgess said. In recent years, vacationing tourists have been attacked off beaches in remote parts of the globe, such as Cocos Island in the Indian Ocean, where none was reported in the past, he said.

There were four fatal attacks last year — an average number — compared with only one in 2007, which marked a two-decade low. Two of the deaths were in Mexico, one was in Australia and one was in the United States.

La Niña, a meteorological condition that brings water masses and deep ocean creatures closer to shore, probably was a factor in the deaths of two male surfers and injury of a third that occurred in less than a month along a resort-studded stretch of Mexico’s southern Pacific coast, Burgess said. The U.S. fatality was a 66-year-old man swimming at Solana Beach, Calif., while the Australian death occurred along the country’s eastern coast and involved a 16-year-old boy.

The number of shark attacks in the United States, which typically makes up about two-thirds of the total worldwide, dropped from 50 in 2007 to 41 in 2008, Burgess said. Thirty-two of those attacks were in Florida — the same number as the previous year — followed by North Carolina and South Carolina, with three each; Hawaii, two; and California, one.

Florida, with its warm waters, has more sharks, including black tip sharks and spinner sharks, species not found in lower temperatures, Burgess said. “A lot less attacks occur off Long Island, New York, than Florida simply because there are fewer sharks up there,” he said.

Within Florida, Volusia County continued its dubious distinction as the world’s shark bite capital with 22 incidents, its highest yearly total since 2001, Burgess said. Attractive waves off New Smyrna Beach on the central Atlantic coast are popular with surfers, he said.

As in past years, surfers accounted for most of the world’s attacks — 57 percent — followed by swimmers and waders, 36 percent; and divers, 8 percent, he said. These numbers are rounded up, which is why they total more than 100 percent.

“Surfers are the heavy favorites largely because the splashing of arms and particularly the kicking of feet at the water’s surface where visibility is poor is provocative to sharks,” Burgess said. “They result in what we think are cases of mistaken identity, where the shark interprets the irregular splashing to be activities of its normal prey.”

As a group, surfers seem to accept the risks of pursuing a sport in the ocean, he said.

“I’ve yet to find a surfer who says he or she won’t go back into the water after a bite or a nip,” he said. ‘Some of them may be looking over their shoulders a little bit more than they did before, but the reality is they understand where humans fall in the grand order of things.”

Burgess said he doubts the economic recession is likely to deter surfers because their interest in the recreational activity is so high. “It’s oftentimes not a group that is economically blessed, but all they have to do is drive to the beach with the board and get into the water, and the rest is free,” he said.

To a certain extent, divers, like surfers, pursue their sport as something of an avocation, leaving swimmers and waders as the group most likely to be affected by economic hardship, Burgess said. “These are sort of the average folks that go to the water for recreation, lie on the beach, work on their suntan and take their kids in the surf for a swim,” he said. “I would expect their numbers to decline in 2009.”

Over the long term, though, Burgess expects shark attacks to rise because of a gradual upswing from one decade to the next. “We’ve already surpassed the numbers of attacks in the previous 10-year period,” he said, “so we know this decade will be higher than the last.”

This burst of speciation over a 5-million-year span was one of three major radiations of flowering plants, known as angiosperms. The study focuses on diversification in the rosid clade, a group with a common ancestor that now accounts for one-third of the world’s flowering plants. The forests that resulted provided the habitat that supported later evolutionary diversifications for amphibians, ants, placental mammals and ferns.

“Shortly after the angiosperm-dominated forests diversified, we see this amazing diversification in other lineages, so they basically set the habitat for all kinds of new things to arise,” said Pamela Soltis, study co-author and curator of molecular systematics and evolutionary genetics at UF’s Florida Museum of Natural History. “Associated with some of the subsequent radiations is even the diversification of the primates.”

The study appearing online in next week’s Proceedings of the National Academy of Sciences is the first to show the evolutionary relationships of these plants and provide evidence for their rapid emergence and diversification.

Because the diversification happened so quickly, at least in evolutionary terms, molecular methods were needed to sort out the branches of the rosid clade’s phylogenetic tree, a sort of family tree based on genetic relationships. Only after sequencing many thousands of DNA base pairs are genetic researchers able to tease apart the branches and better understand how plant species evolved.

Often, when scientists discuss the rapid radiation of flowering plants, they talk as if there had been one massive burst of early diversification, said Doug Soltis, co-author and chair of UF’s botany department.

“I think one thing that becomes very clear from our phylogenetic trees when you look at them closely is that it’s not just one big explosion of species within the flowering plants,” Doug Soltis said. “There’s a series of explosions.”

The rosid clade’s diversification is one of at least three bursts in the early evolution of flowering plants. More than 300,000 species of angiosperms exist, classified into an estimated 15,000 genera and more than 400 families. Understanding how these plants are related is a large undertaking that could help ecologists better understand which species are more vulnerable to environmental factors such as climate change.

“We really need to know on a finer scale how these species are related and on different parts of the planet how members of the clade are related,” Doug Soltis said. “That’s where the action is going to be in terms of how this clade responds to climate change. How members of this large clade respond is really going to determine the fate of most of the organisms on the planet.”

The study’s authors sequenced 25,000 base pairs of DNA and sampled a broad range of 104 species from the rosid clade. Using a phylogenetic tree to date the diversification of lineages requires the use of a molecular clock, which calibrates the degree of change that has occurred over time.

“You can assume that over time DNA sequences accumulate change, and things that are more similar to each other in general would have diverged from each other more recently than things that are more different,” Pam Soltis said.

But different genes have different rates of evolution, as do different clades. To compensate, the study used algorithms that accommodate the different rates. Rosid fossils selected by co-author Steven Manchester, the museum’s curator of paleobotany, were used to help calibrate that clock by setting minimum ages for member species.

The study’s first author is Hengchang Wang, who worked at the Florida Museum as a post-doctoral fellow but is now with The Chinese Academy of Science. Other authors include former post-doctoral fellows Michael J. Moore from Oberlin College and Charles D. Bell from the University of New Orleans. UF botany graduate students Samuel F. Brockington and Maribeth Latvis, former UF undergraduate Roolse Alexandre, and Charles C. Davis of Harvard University also contributed to the study.

GAINESVILLE, Fla. — The largest snake the world has ever known — as long as a school bus and as heavy as a small car — ruled tropical ecosystems only 6 million years after the demise of the fearsome Tyrannosaurus rex, according to a new discovery published in the journal Nature.

Partial skeletons of a new giant, boa constrictor-like snake named “Titanoboa” found in Colombia by an international team of scientists and now at the University of Florida are estimated to be 42 to 45 feet long, the length of the T-Rex “Sue” displayed at Chicago’s Field Museum, said Jonathan Bloch, a UF vertebrate paleontologist who co-led the expedition with Carlos Jaramillo, a paleobotanist from the Smithsonian Tropical Research Institute in Panama.

Researchers say the extinct snake was even larger than the wildest dreams of directors of modern horror movies.

“Truly enormous snakes really spark people’s imagination, but reality has exceeded the fantasies of Hollywood,” said Bloch, who is studying the snake at the Florida Museum of Natural History on the UF campus. “The snake that tried to eat Jennifer Lopez in the movie ‘Anaconda’ is not as big as the one we found.”

Jason Head, a paleontologist at the University of Toronto in Mississauga and the paper’s senior author, described it this way: “The snake’s body was so wide that if it were moving down the hall and decided to come into my office to eat me, it would literally have to squeeze through the door.”

Besides tipping the scales at an estimated 1.25 tons, the snake lived during the Paleocene Epoch, a 10-million-year period immediately following the extinction of the dinosaurs 65 million years ago, Bloch said.

The scientists also found many skeletons of giant turtles and extinct primitive crocodile relatives that likely were eaten by the snake, he said. “Prior to our work, there had been no fossil vertebrates found between 65 million and 55 million years ago in tropical South America,
leaving us with a very poor understanding of what life was like in the northern Neotropics,” he said. “Now we have a window into the time just after the dinosaurs went extinct and can actually see what the animals replacing them were like.”

Size does matter because the snake’s gigantic dimensions are a sign that temperatures along the equator were once much hotter. That is because snakes and other cold-blooded animals are limited in body size by the ambient temperature of where they live, Bloch said.

“If you look at cold-blooded animals and their distribution on the planet today, the large ones are in the tropics, where it’s hottest, and they become smaller the farther away they are from the equator,” he said.

Based on the snake’s size, the team was able to calculate that the mean annual temperature at equatorial South America 60 million years ago would have been about 91 degrees Fahrenheit, about 10 degrees warmer than today, Bloch said.

The presence of outsized snakes and turtles shows that even 60 million years ago the foundations of the modern Amazonian tropical ecosystem were in place, he said.

Fossil hunting is usually difficult in the forest-covered tropics because of the lack of exposed rock, Bloch said. But excavations in the Cerrejon Coal Mine in Northern Colombia exposed the rock and offered an unparalleled opportunity for discovery, he said.

After the team brought the fossils to the Florida Museum of Natural History, it was UF graduate students Alex Hastings and Jason Bourque who first recognized they belonged to a giant snake, Bloch said. Head, an expert on fossil snakes, worked with David Polly, a paleontologist at the University of Indiana, to estimate the snake’s length and mass by determining the relationship between body size and vertebral — backbone — size in living snakes and using that relationship to figure out body size of the fossil snake based on its vertebrae.

Harry W. Greene, professor in the department of ecology and evolutionary biology at Cornell University and one of the world’s leading snake experts, said the “colossal” ancient boa researchers found has “important implications for snake biology and our understanding of life in the ancient tropics.”

“The giant Colombian snake is a truly exciting discovery,” said Greene, who wrote the book “Snakes: The Evolution of Mystery in Nature.” “For decades herpetologists have argued about just how big snakes can get, with debatable estimates of the max somewhat less than 40 feet.”

Laurel wilt disease, caused by a fungus transmitted by the invasive redbay ambrosia beetle, kills avocado and several native trees including redbay, said Jonathan Crane, a professor with UF’s Institute of Food and Agricultural Sciences and co-author of a paper estimating the disease’s financial impact. The paper is expected to be published later this year.

“The scenario is not looking good, if we are right,” said Crane, at UF’s Tropical Research and Education Center in Homestead.

The state’s avocado crop earns about $30 million wholesale each year, said Edward “Gilly” Evans, an agricultural economist at the Homestead center and another co-author. Commercial avocados grow on 7,500 acres, almost exclusively in Miami-Dade County, and account for more than 60 percent of Florida’s tropical fruit production.

Avocado is also an important fruit tree for Florida homeowners — about 60,000 residents have at least one in their yards, he said.

If the disease cuts Florida’s commercial avocado crop in half — something experts say could happen — it could cost the state $27 million in total economic impact and enough lost worker hours to equal 275 full-time jobs, Evans said.

So UF researchers are scrambling to develop damage estimates and management strategies.

They’ve evaluated about 30 percent of the 28 avocado varieties grown in Florida; all have been susceptible to the disease, though not all have died, said Jorge Peña, an entomology professor at the Homestead center.

There is no standard method for controlling the fungus or the beetle, but researchers are testing pesticides and repellents, Peña said.

Some redbay trees may be resistant to the disease, said forest pathologist Jason Smith, an assistant professor with UF’s School of Forest Resources and Conservation in Gainesville. Researchers will investigate factors associated with resistance, in the hope that tolerant varieties can be identified and developed.

The disease was unknown to science until 2004. The beetle, first found in the United States in 2002, is native to Asia and may have arrived in wood products, packing materials or pallets.

Laurel wilt is in South Carolina, Georgia and Florida, where it’s reached as far south as Okeechobee County and as far west as Columbia County.

“The disease is moving fairly rapidly, so it’s clear it will arrive (in Miami-Dade County) sooner or later,” said Randy Ploetz, a plant pathologist at the Homestead center.

In Florida, laurel wilt apparently spreads at least two ways, Crane said.

One is via the beetle’s natural reproduction and migration, which expands its range 20 or 30 miles per year. Also, redbay is used as firewood and for outdoor grilling. Because the disease has leapfrogged around the state, researchers believe beetle-infested wood has been sold, he said.

Crane urges Floridians to report laurel wilt symptoms on avocado or redbay trees to the state Division of Plant Industry at 1-888-397-1517. Symptoms include wilted stems and leaves, black streaking in the wood, and strings of compacted sawdust protruding from tree trunks.

DPI and U.S. Department of Agriculture experts are monitoring several counties for redbay ambrosia beetles with traps and inspections, said DPI spokeswoman Denise Feiber.

There’s more at stake for Florida than the avocado industry. Laurel wilt has killed 99 percent of infected redbay trees in many areas, said Smith. Also at risk: sassafras, camphor, silkbay, swampbay, pondspice and an endangered species, pondberry.

Smith developed a test that identifies diseased trees in less than an hour, even if the fungus is present in small amounts. The test will be available to diagnostic labs around the Southeast.

For more information, see “Redbay Ambrosia Beetle-Laurel Wilt Pathogen: A Potential Major Problem for the Florida Avocado Industry,” http://edis.ifas.ufl.edu/HS379.

There are some 4,000 master gardeners in Florida, in 58 of the state’s 67 counties.

The program began in 1972 in the state of Washington, when a county extension agent felt guilty about not being able to answer every call that came in. So he decided to train a cadre of volunteers to help.

Florida started its program in 1979, and it’s been chugging along strong ever since. According to the most recent calculations, the program’s volunteers have donated 5.4 million hours, worth some $83 million to taxpayers.

Here’s how it works: Interested participants go through at least 50 hours of training sponsored by the University of Florida’s Institute of Food and Agricultural Sciences and local county extension offices that includes a smattering of everything from gardening to nematology to soil testing.

After the training, new master gardeners must serve at least 75 volunteer hours within the first year of certification and 35 hours in subsequent years. To renew their certification after the first year, they must undergo 10 hours of annual training.

Master gardener duties include everything from manning the desk in the county extension office to fielding questions from callers or walk-in clients.

“I think master gardeners have one of the toughest jobs in extension,” said Tom Wichman, the program’s state coordinator. “The questions that come in are very diverse.”

John Robinson, a master gardener in Escambia County since 1992, can tell you all about that.

He’s logged more than 20,000 volunteer hours, and says the questions can be doozies.

Clients have brought in giant spiders and pygmy rattlesnakes, he said, sometimes live; sometimes not. There are always questions to be answered about tomatoes. And turfgrass causes consternation for many who’ve moved to Florida for the first time and are trying to start or maintain their first St. Augustinegrass lawn. “They see their neighbor do something, and they wonder if they should do it, too,” he said.

Other master gardener duties might include tending a demonstration garden, teaching residents how to prune trees or grapevines or how to start a garden.

Norma Samuel, a horticulture extension agent in Marion County, supervises a team of roughly 130 master gardeners.

Her volunteers each serve on a committee with different responsibilities, such as running a speakers’ bureau and maintaining a demonstration vegetable garden. One volunteer came up with an idea and secured funding for a mobile plant clinic that volunteers take to county events and use to distribute educational information on a host of gardening-related topics.

“Oh, they’re a tremendous resource to us,” she said. “They pretty much do anything an (extension) agent would do.”

The next Master Gardener program training begins in many counties in February and Wichman says you don’t need to have a green thumb to be a great master gardener. Much of the training focuses on teaching volunteers how to find the information they need.

“There’s no prerequisite as far as having to have plant knowledge,” he says. “Just the willingness to learn and to share what you learn with others.”

Would-be master gardeners should contact their local coordinator at www.gardeningsolutions.ifas.ufl.edu/mastergardener/contact_us.shtml.

Often viewed as fierce opponents in controversies pitting jobs against wildlife — such as the dispute over logging and spotted owls — unions and environmental groups are banding together to stop groundwater contamination in the Silicon Valley, toxic chemical spills in New Jersey, air pollution from the nation’s ports and other hazards that affect communities and workplaces alike, said Brian Mayer, a UF sociology professor.

“Health issues are increasingly becoming the common ground on which blue-green coalitions are developing across the United States,” he said. “Recognizing that the same toxins that cause workplace hazards escape into surrounding communities has brought workers and environmentalists together to look out for everyone’s protection.”

In his new book “Blue-Green Coalitions: Fighting for Safe Workplaces and Healthy Communities,” published this month by Cornell University Press, Mayer debunks popular images of these groups. “Stereotypes of blue-collar workers as interested only in putting food on the table and being willing to do anything to trade off the environment are no truer than perceptions of an environmentalist as someone middle class or upper class who is preoccupied with outdoor leisure opportunities,” he said.

“Mayer’s book fills a huge gap in our knowledge of how unions and environmentalists have worked together and why,” said J. Timmons Roberts, a sociology professor at the College of William and Mary and co-author of the book “A Climate of Injustice; Global Inequality, North-South Politics and Climate Policy.” He added that Mayer “offers creative ideas about how this potentially powerful coalition might work together in the future.”

An increase in environmental risks has encouraged unions and environmentalists to unite, Mayer said. In past economic booms, Americans were excited about new factories, while today, with the transfer of heavy industry overseas, larger numbers of workers have service jobs, which can put them in close proximity to a variety of chemicals, he said.

The Service Employees International Union, which represents vast numbers of employees in the service and hospitality industry, is one of the few unions in the United States whose membership is expanding, Mayer said.

“If you think about hotel workers, custodial workers and other employees who come into direct contact with a lot of cleaning chemicals, their jobs can be dangerous,” he said. “More and more of these workers are concerned with health.”

The decline of organized labor to about 12 percent of the nation’s work force from 36 percent in 1945 also has encouraged unions to reach out to nontraditional allies by collaborating with environmentalists, he said.

One example of such an affiliation is the formation of Alliance for a Healthy Tomorrow in Boston in 2001, a grassroots coalition that worked to pass a Massachusetts law requiring that proponents of a product prove its safety before it goes on the market instead of forcing the public to make a case later that something is hazardous, Mayer said. Today the organization works with scientists, public health experts and community activists across the state in promoting the substitution of safer alternatives for hazardous substances, he said.

Some blue-green coalitions began as early as the 1980s, as with the New Jersey Work Environmental Council helping to put into place the nation’s first right-to-know legislation, giving New Jersey workers and residents access to information about the use and storage of toxic substances, Mayer said. In California, the Silicon Valley Toxics Coalition fought for similar right-to-know legislation, as well as addressed health concerns about electronics, expanding into a global presence today as high-tech industries have moved overseas, he said.

One of the most recent initiatives has occurred with the ports of Los Angeles and Long Beach, which use the revenue from a small tax on shipping containers entering the ports to update and retrofit trucks to make them cleaner and more efficient, Mayer said. Ships, trains and diesel trucks that congregate in and around ports pollute city air and have been blamed for about half of the emissions in the Los Angeles metropolitan area, he said.

So suggests a paper that appears in a recent issue of the journal Oecologia.

Sue Natali, a postdoctoral associate in botany at the University of Florida and the paper’s lead author, compared mercury levels in soils under trees growing in air enriched with carbon dioxide to soil beneath trees in ambient air. Carbon dioxide, the main greenhouse gas, has increased nearly 40 percent since the industrial revolution and is expected to continue climbing unless power plant and other emissions are restricted or curtailed.

Natali’s main finding: Soil samples from the carbon dioxide-enriched soil contained almost 30 percent more mercury — apparently because the soil had greater capacity than soil in today’s atmosphere to trap and hold on to mercury.

On the one hand, Natali said, that increased capacity could slow the mercury’s release into water — its main conduit to aquatic wildlife and the fish that pose a hazard to people. On the other, it means that even if policy makers manage to ban or severely restrict mercury emissions, the metal will remain a source of pollution for a long time.

“From the time you cut off mercury emission to the time it positively affects fish, you might have this lag, because the soils hold on to the mercury better,” Natali said.

Global mercury emissions today range from 4,400 to 7,500 tons per year, according to the Environmental Protection Agency. Natural sources such as volcanoes account for about half, with coal-fired power plants, smelters and incinerators contributing the remainder.

When mercury is belched into the air, it returns to Earth via rain, with bacteria and other natural processes converting it to methylmercury in lakes, rivers and oceans. Methylmercury builds up through the food chain, with the flesh of the biggest, most sought-after predator fish — tuna, swordfish, king mackerel and so on — containing the highest concentrations. That’s why the federal government has advised pregnant women, children and other groups considered vulnerable to limit their consumption.

Natali said scientists have long recognized mercury levels in soil spike under trees, averaging four times the concentration in open areas.

That’s because trees effectively scavenge the poison from the atmosphere. Leaves and stems collect rainwater, and with it mercury; trees drop mercury-laden leaves on the ground, and trees take in the metal through their stomata, or breathing pores on leaves.

Scientists also have shown repeatedly that increased atmospheric carbon dioxide leads to increased plant and tree growth. Natali said she launched her research to find out whether that process would in turn have any effect on pollution from mercury and other metals.

Fortunately, two experimental sites were already in place: the free-air carbon dioxide enrichment experiments at forests in North Carolina and Tennessee, operated by Duke University and Oak Ridge National Laboratory, respectively. These sites consist of plots in naturally growing forests surrounded by vertical pipes that constantly pump out carbon dioxide — and have done so since 1996, for the North Carolina site, and 1998, for the Tennessee site. The systems surround deciduous and coniferous trees in the plots with 200 parts per million more carbon dioxide than ambient air, or between 549 and 582 parts per million. That is the anticipated concentration in the air in 2050 without new emissions restrictions, Natali said.

Natali assessed mercury levels in rain that struck the canopy and then flowed down stems and trunks; in rain that fell directly from the canopy to the forest floor, and in leaves that fell below the trees, or “leaf litter.”

To her surprise, none contained particularly elevated levels of the poison. In fact, although the trees in the enriched plots produced more leaf litter, mercury concentrations in the leaves actually decreased. The uptick in mercury in the soil apparently happened instead because of “changes in soil properties” that occur in the enriched environments, according to the paper. These changes increase the soils’ mercury storage capacity.

Johan Varekamp, a professor of earth science at Wesleyan University who also studies mercury and the environment, agreed that Natali’s results can be seen as both negative and positive. Mercury will stick around longer in a carbon-dioxide-enriched world, he said, but it also will remain bound to the soil for a longer period.

“I agree with her conclusion that with further cutbacks in mercury emissions, there will be a delay in delay in direct response,” he said. That said, “the mercury fluxes to the coastal zone related to past emissions may then be less damaging to the ecosystems.”