Invasive seaweed shelters tiny native critters on Georgia mudflats
Oct24

Invasive seaweed shelters tiny native critters on Georgia mudflats

On the tidal mudflats of Georgia and South Carolina, the red Japanese seaweed Gracilaria vermiculophylla is gaining a foothold where no native seaweeds live. Only debris and straggles of dead marsh grass used to break the expanse of mud at low tide. Crabs, shrimp, and small crustaceans mob the seaweed in abundance. What makes it so popular? Not its food value. On mudflats near Savannah, Ga., Jeffrey Wright and colleagues found that the tiny native crustacean Gammarus mucronatus (one of the 9,500 species of amphipod, which includes sand fleas) does not eat much of the seaweed. Rather, its attraction is structural. The seaweed protects the small crustaceans from predators at high tide and from the dry heat of the flats at low tide. G. mucronatus was up to 100 times as abundant on seaweed invaded mudflats, the authors report in the October issue of Ecology, out this week. The arrival of an aggressive invader disrupts the food webs and physical and chemical characteristics of the environment it enters. Disruption is often bad for native species that get shaded, crowded, or eaten by the invader, and reports of the disastrous consequences of invasive species have grown familiar. But the story for individual species is more complicated, as the presence of the invader is sometimes a benefit, either as a new source of food or, as in this case, of shelter. Engineering or food? Mechanisms of facilitation by a habitat-forming invasive seaweed (2014) JT Wright, JE Byers, JL DeVore, and E Sotka. Ecology 95(10): 2699-2706.  [open...

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Old forests store new nitrogen–and may soak up nutrient excesses
Oct23

Old forests store new nitrogen–and may soak up nutrient excesses

Ecologists working in central Pennsylvania forests have found that forest top soils capture and stabilize the powerful fertilizer nitrogen quickly, within days, but release it slowly, over years to decades. The discrepancy in rates means that nitrogen can build up in soils, David Lewis, Michael Castellano, and Jason Kaye report in the October 2014 issue of ESA’s journal Ecology, published online this week. Forests may be providing an unappreciated service by storing excess nitrogen emitted by modern agriculture, industry, and transport before it can cause problems for our waterways. Nitrogen is an essential nutrient, required for all living things to live and grow. Though a major component of the air, it is largely inaccessible, captured only through the metabolism of certain microbes or washed to earth in the form of ammonia, nitrogen oxides, or organic material by rain, snow, and fog. On land, microbes, fungi, and plants incorporate what doesn’t wash away into proteins, DNA, and other biological components. Organic matter in the soil – the remains of fallen leaves, animal droppings, and dead things in various states of decay – can also capture newly deposited nitrogen, holding it stable in the soil. Mature forests store nitrogen more efficiently than young forests recovering from clear-cuts the authors found, because they have been accumulating organic matter on the forest floor for a century or more. When a forest is clear cut, erosion soon follows, washing away top soil. A young stand of trees a decade old is beginning to rebuild the organic layer, but it will take many autumns to accumulate. The orderly succession of changes in resident species as a forest grows and ages is a classic preoccupation of ecological theory. The exchange of nutrients among the species and the non-living landscape also changes with succession, and the discovery that nitrogen accumulates in the organic soil indicates something important about how an ecosystem’s nutrient economy ages. It was thought, up through the 1970s and early 80s, that an ecosystem grows like a person. At some point, forests, like people, stop getting bigger and adding new biomass. Ecologists argued that the ability to capture incoming nutrients stopped with the end of growth. But by the mid-80s, it was clear that mature ecosystems did continue to absorb nitrogen, mostly in soil. By showing that nitrogen capture is much faster than its release, Lewis and colleagues suggest a mechanism by which old ecosystems can accumulate new inputs of nutrients. Because soils rich in organics can quickly incorporate nitrogen, forest soils have the potential to absorb excess nitrogen that has been newly added to the biosphere through human activities. Application of synthetic nitrogen...

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Water rises, cattle graze, dunes walk on the Kalahari
Oct15

Water rises, cattle graze, dunes walk on the Kalahari

There is water under the dry sands of the Kalahari. Perversely, this gift has lead to a cycle of land degradation.

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River Flow By Design: Environmental Flows Support Ecosystem Services In Rivers Natural And Novel
Oct09

River Flow By Design: Environmental Flows Support Ecosystem Services In Rivers Natural And Novel

“When the sun peeped over the Sierra Madre, it slanted across a hundred miles of lovely desolation, a vast flat bowl of wilderness rimmed by jagged peaks. On the map the Delta was bisected by the river, but in fact the river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf.”

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Volunteer ‘eyes on the skies’ track peregrine falcon recovery in California
Sep11

Volunteer ‘eyes on the skies’ track peregrine falcon recovery in California

Datasets from long-running volunteer survey programs, calibrated with data from sporadic intensive monitoring efforts, have allowed ecologists to track the recovery of peregrine falcons in California and evaluate the effectiveness of a predictive model popular in the management of threatened species. In recovery from the deadly legacy of DDT, American peregrine falcons (Falco peregrinus anatum) faced new uncertainty in 1992, when biologists proposed to stop rearing young birds in captivity and placing them in wild nests. Tim Wootton and Doug Bell published models that year in Ecological Applications, projecting population trends for the falcon in California, with and without direct human intervention in the falcons’ reproductive lives. They concluded that the birds would continue to recover without captive rearing, though the population growth rate might slow. Fledgling introductions had bolstered wild falcon numbers and genetic diversity, but survival would ultimately depend on cleaning up lingering DDT contamination to create healthy conditions for wild birds, they argued. This month, they return to their 1992 predictions to see how the American peregrine falcons have fared over the last two decades, with a new report featured on the cover of the September 2014 issue of Ecological Applications. Though falcon numbers are lower than hoped for, data from volunteer survey programs, calibrated with more intensive surveys by wildlife biologists, confirmed a recovery trajectory well within the trends Wootton and Bell predicted. “The challenge was to come up with data,” said Wootton. “Once a species falls off the endangered species list, there is not a lot of funding to track how management, or lack of management, is doing,” he said. “There was limited data that was appropriate being collected on the falcon, so we turned to a couple of well-known bird censuses that cover wide geographic areas.” The follow-on study provided insights in the use of volunteer-generated data as well as an important test of population viability analysis, a tool increasingly used to evaluate alternative management plans and identify conservation priorities for endangered species, including sea turtles, grizzlies, and desert tortoises. It supported the importance of considering the health and behavior of geographic groups of a threatened species within a larger population. The 1992 paper identified falcon population “sinks” in parts of Southern California where chemical contamination lingered and the birds could not maintain numbers without migrants from healthier areas. Unfortunately, the falcon’s recovery has continued to lag in these areas. Once widespread across North America, the world’s fastest bird had disappeared from the east by mid-century and was near extinction on the continent by 1975, when a survey found only 159 breeding pairs of American peregrine falcons. Chicks often did not survive to...

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Pikas on Ice
Aug25

Pikas on Ice

Another fine guest post from Holly Menninger and the ESA2014 EcoCommCrew: Adorable and fuzzy, American pikas have become the spokes-critter for the consequences of climate change in alpine areas. Pika sketch by biological illustrator, Jennifer Landin.

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In India, vaccination, sterilization of stray dogs curbs rabies better than culls
Aug14

In India, vaccination, sterilization of stray dogs curbs rabies better than culls

When people encounter stray dogs in Jaipur, India, they cross the street to put distance between themselves and a potentially deadly bite. Street dogs are endemic in Indian cities and experience has taught citizens caution. The incidence of rabies in the stray population is uncomfortably high, resulting in about 20,000 human cases every year. Most cities have tried to solve the problem by killing the dogs, but a few communities are now experimenting with capturing, vaccinating, sterilizing, and then releasing the dogs back to the streets. The more expensive vaccination and sterilization strategy works better, says wildlife biologist Andrew Yoak of the Ohio State University, who presented the results of his work to model and understand the population effects this afternoon at the Ecological Society of America’s 99th Annual Meeting, held this year in Sacramento, Cal. “If you are trying to stop a disease spread by fighting, you don’t want to create a population vacuum that a bunch of new dogs will rush to fill – leading to a big peak in fights for new territory,” Yoak said. Sterilization means fewer puppies, but also reduces the number of conflicts with people, because mother dogs bite to defend their puppies. Rabies cases are the most numerous just after whelping season. Kids in poor neighborhoods are the most likely to be bitten. Yoak described ways managers can use modeling and population surveys to get the most bang for their vaccination buck.   Contributed oral session 121-1: Catching dogs with turtles: Using agent based modeling to optimize street dog control Thursday, August 14, 2014: 1:30 PM 314, Sacramento Convention Center Andrew James Yoak, Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus,...

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History of fire and drought shapes the ecology of California, past and future
Aug06

History of fire and drought shapes the ecology of California, past and future

Fire season has arrived in California with vengeance in this third year of extended drought for the state. A series of large fires east of Redding and Fresno, in Yosemite, and on the Oregon border prompted Gov. Jerry Brown to declare a state of emergency on Sunday, August 3rd. As force of destruction and renewal, fire has a long and intimate history with the ecology of California. Ecological scientists will discuss aspects of that history in detail at the upcoming 99th Annual Meeting of the Ecological Society of America on August 10 – 15th, 2014. “Big fires today are not outside the range of historical variation in size,” said Jon Keeley, an ecologist based in Three Rivers, Cal., with the U.S. Geological Survey’s Western Ecological Research Center, and a Fellow of the Ecological Society. Keeley will present research on the “association of megafires and extreme droughts in California” at the Annual Meeting as part of a symposium on understanding and adapting to extreme weather and climate events. He will synthesize his research on the history of wildfire across the entire state, contrasting historical versus contemporary and forested versus non-forested patterns of wildfire incidence. He and his colleagues reviewed Forest Service records dating to 1910, as well as a wealth of newspaper clippings, compiled by a Works Progress Administration archival project, that stretch back to the middle of the last century. Understanding historical fire trends, Keeley said, means recognizing that when we talk about wildfire in California we are talking about two very different fire regimes in two different ecosystems: the mountain forests and the lower elevation chaparral, oak woodlands, and grasslands. The chaparral shrublands of southern California, and similar sagebrush ecosystems in the Great Basin, are not adapted to the kind of frequent fire typical of the mountain conifer forests in California. Fires in the lower elevation ecosystems are always crown fires, which kill most of the vegetation. In the millennia before humans arrived, these ecosystems burned at intervals of 100 to 130 years. These lower elevation ecosystems experienced unprecedented fire frequency in the last century, with fire returning to the same area every 10 to 20 years, altering the ecology of the landscape. “In Southern California, lower elevation ecosystems have burned more frequently than ever before. I think it’s partly climate, but also people starting fires during bad conditions,” Keeley said. Bad conditions include extended droughts and dry fall days when the Santa Ana winds blow through the canyons. In high elevation conifer forests, spring temperatures and drought are strongly correlated with fire, and Keeley thinks climate change and management choices are likely playing a role in current...

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