January 11, 2011, 6:30 AM CT

Lake Erie hypoxic zone doesn't affect all fish

Large hypoxic zones low in oxygen long have been thought to have negative influences on aquatic life, but a Purdue University study shows that while these so-called dead zones have an adverse affect, not all species are impacted equally.

Tomas Hook, an assistant professor of forestry and natural resources, and former Purdue postdoctoral researcher Kristen Arend used output from a model to estimate how much dissolved oxygen was present in Lake Erie's hypoxic zone each day from 1987 to 2005. That information was compared with biological information for four fish species to assess the hypoxic zone's impact on the sustainability of their habitats.

"The term 'dead zone' sounds really scary," Hook said. "But in a lot of cases a hypoxic zone will not be negative for all fish species".

Lake Erie's hypoxic zone is very large - about the size of Rhode Island and Delaware combined. And while the Gulf of Mexico's dead zone has received more attention, during some years Lake Erie's zone appears to be greater in volume.

Hypoxia occurs when water has less than two parts per million of dissolved oxygen. Discharge of nutrients, such as nitrogen and phosphorus, leads to excess algae growth. When that algae settles to the bottom and decomposes, oxygen is consumed......... Posted by: Kelly      Read more         Source

January 11, 2011, 6:13 AM CT

Shellfish is now safer to eat

New technology to make shellfish safer to eat has been pioneered by researchers at Queen's University Belfast.

The new test, developed at Queen's Institute for Agri-Food and Land Use, not only ensures shellfish are free of toxins before they reach the food chain but is likely to revolutionise the global fishing industry.

While the current process for monitoring potentially dangerous toxins in shellfish takes up to two days, the new test slashes the testing time to just 30 minutes using new biosensor technology and provides a much more reliable result.

The test detects paralytic shellfish poisons, which paralyse anyone who consumes them and kills around 25 per cent people who are poisoned.

Leading the project is Professor Chris Elliott, Director of the Institute of Agri-Food and Land Use at Queen's School of Biological Sciences, who said: "Toxins secreted by algae, and which concentrate in shellfish, are a major hazard to consumers and can bring huge economic losses to the aquaculture industry.

"While the existence of these toxins has been known for some time, there have been major concerns about the effectiveness of tests used to detect them. There is also growing evidence that climate change is causing a number of more toxic episodes across the world, resulting in the closure of affected shellfish beds......... Posted by: Kelly      Read more         Source

January 10, 2011, 6:29 AM CT

Ginger for conserving stag beetles

The humble ginger root could be the key to conserving the UK's largest and most spectacular terrestrial beetle � the stag beetle. Ecologists from Royal Holloway, University of London and the University of York have developed a series of new methods to monitor stag beetle numbers � including ginger lures to trap adult beetles and tiny microphones to detect sounds made by the larvae in their underground nests. Conservation efforts have been hampered until now because ecologists lacked a reliable way of monitoring stag beetle numbers.

The new research, reported in the Royal Entomological Society's journal Insect Conservation and Diversity, observed that a combination of ginger-baited aerial traps to catch adult stag beetles, plus tiny microphones to record the underground larvae's sounds and samplers to detect the chemicals they emit, give an accurate picture of the species' abundance.

As per Dr Deborah Harvey, one of the study's authors: "Our new methods offer genuine promise for monitoring the population of this elusive and rare insect, one that we think is declining across much of its European range. We need to know where the stag beetle lives � and in what numbers � to be able to conserve it effectively".

Harvey and her colleagues discovered ginger was irresistible to adult stag beetles only after testing the attractiveness of a number of other fruit and vegetables � including banana, strawberry, tomato and cherry � as well as wine and beer. Ginger works because it contains large amounts of alpha copaene, a chemical known to attract other insects that live in dead and decaying wood......... Posted by: Kelly      Read more         Source

January 10, 2011, 6:21 AM CT

Wildflower colors tell butterflies how to do their jobs

The recipe for making one species into two requires time and some kind of separation, like being on different islands or something else that discourages gene flow between the two budding species.

In the case of common Texas wildflowers that share meadows and roadside ditches, color-coding apparently does the trick.

Duke University graduate student Robin Hopkins has found the first evidence of a specific genetic change that helps two closely related wildflowers avoid creating costly hybrids. It results in one of the normally light blue flowers being tagged with a reddish color to appear less appetizing to the pollinating butterflies which prefer blue.

"There are big questions about evolution that are addressed by flower color," said Hopkins, who successfully defended her doctoral dissertation just weeks before seeing the same work appear in the prestigious journal Nature

What Hopkins found, with her thesis adviser, Duke biology professor Mark Rausher, is the first clear genetic evidence for something called reinforcement in plants. Reinforcement keeps two similar proto-species moving apart by discouraging hybrid matings. Flower color had been expected to aid reinforcement, but the genes had not been found.

In animals or insects, reinforcement might be accomplished by a small difference in scent, plumage or mating rituals. But plants don't dance or choose their mates. So they apparently exert some choice by using color to discourage the butterflies from mingling their pollen, Hopkins said......... Posted by: Kelly      Read more         Source

January 6, 2011, 6:13 PM CT

Biofuel grasslands better for birds

Developing biofuel from native perennials instead of corn in the Midwest's rolling grasslands would better protect threatened bird populations, Michigan State University research suggests.

Federal mandates and market forces both are expected to promote rising biofuel production, MSU biologist Bruce Robertson says, but the environmental consequences of turning more acreage over to row crops for fuel are a serious concern.

Ethanol in America is chiefly made from corn, but research is focusing on how to cost-effectively process cellulosic sources such as wood, corn stalks and grasses. Perennial grasses promise low cost and energy inputs - planting, fertilizing, watering - and the newly released study quantifies substantial environmental benefits.

"Native perennial grasses might provide an opportunity to produce biomass in ways that are compatible with the conservation of biodiversity and important ecosystem services such as pest control," Robertson said. "This work demonstrates that next-generation biofuel crops have potential to provide a new source of habitat for a threatened group of birds".

With its rich variety of ecosystems, including historic prairie, southern Michigan provided a convenient place to compare bird populations in 20 sites of varying size for each of the three fuel feedstocks. Grassland birds are of special concern, Robertson said, having suffered more dramatic population losses than any other group of North American birds......... Posted by: Kelly      Read more         Source

December 16, 2010, 8:01 AM CT

Shellfish That Aren't Safe To Eat

By Susan Brown.

Red tides and similar blooms can render some seafood unsafe to eat, though it can be difficult to tell whether a particular batch harbors toxins that cause food poisoning.

A new kind of marker developed by chemists at the University of California, San Diego, and published in the journal ChemComm makes it easier to see if shellfish are filled with toxin-producing organisms.

Mussels and oysters accumulate single-celled marine creatures called dinoflagellates in their digestive systems as they filter seawater for food. Commonly dinoflagellates are harmless, but sometimes they produce dangerous toxins. The trick is figuring out when.

Researchers think symbiotic bacteria that live on the surface of dinoflagellates probably help synthesize the toxins, but no one is sure how. Genetic tools often used to sort out such relationships don't work for dinoflagellates, which have enormous genomes that are not well understood.

So chemistry professor Michael Burkhart's group took a different approach. They set up a system to add a fluorescent tag to an enzyme that makes one kind of toxin, okadaic acid, but with a twist. By handing the tag to a the molecule that turns the enzyme on, they ensured that only those parts of cells that are capable of making the toxin would glow......... Posted by: Kelly      Read more         Source

December 16, 2010, 7:47 AM CT

Dolphin by-catch includes genetic relatives

Dolphins along coast of Argentina could experience a significant loss of genetic diversity because some of the animals that accidently die when tangled in fishing nets are related. As per a new genetic analysis published this week in the journal PLoS One, Franciscana dolphins that die as by-catch are more than a collection of random individuals: a number of are most likely mother-offspring pairs. This result, which suggests reduced genetic diversity and reproductive potential, could have significant implications for the conservation of small marine mammals.

"It has always been assumed that dolphins could be entangled in fishing nets with family members, but this is one of the very few analyses to demonstrate this result," says Martin Mendez, a postdoctoral researcher at the Sackler Institute for Comparative Genomics at the American Museum of Natural History who led the study. "When family members die as by-catch, a portion of genetic identity of a species is lost, and two important demographic elements of a population are removed: a reproductive female and the next generation".

Franciscana dolphins (Pontoporia blainvillei) have a range that hugs the Atlantic coast of Brazil, Uruguay, and Argentina. This species is one of the world's smallest cetaceans and is a member of the river dolphin family, eventhough it actually lives in coastal waters and estuaries. Females probably begin to have calves between two and five years and probably stay with each calf for some time. Because scientists estimate that between two and five percent of the Fransiscana population near Argentina becomes entangled in fishing nets from small-scale operations each year, the by-catch death rate has a significant impact on the population numbers. By-catch is the biggest impact to small cetacean populations world-wide......... Posted by: Kelly      Read more         Source

December 16, 2010, 7:30 AM CT

Polar bears: On thin ice?

Polar bears were added to the threatened species list nearly three years ago when their icy habitat showed steady, precipitous decline because of a warming climate.

But it appears the Arctic icons aren't necessarily doomed after all, as per results of a study published in this week's issue of the journal Nature

The findings indicate that there is no "tipping point" that would result in unstoppable loss of summer sea ice when greenhouse gas-driven warming rises above a certain threshold.

Researchers from several institutions, including the U.S. Geological Survey (USGS), the National Science Foundation (NSF), and the University of Washington, have observed that if humans reduce greenhouse gas emissions significantly in the next decade or two, enough Arctic ice is likely to remain intact during late summer and early autumn for polar bears to survive.

"What we projected in 2007 was based solely on the business-as-usual greenhouse gas scenario," said Steven Amstrup, an emeritus researcher at the USGS and senior scientist at the Montana-based organization Polar Bears International. "That was a pretty dire outlook, but it didn't consider the possibility of greenhouse gas mitigation".

Amstrup is the main author of this week's Nature paper. Co-authors are Eric DeWeaver of NSF, David Douglas and George Durner of the USGS Alaska Science Center, Bruce Marcot of the U.S. Forest Service in Oregon, Cecilia Bitz of the University of Washington, and David Bailey of the National Center for Atmospheric Research in Boulder, Colo......... Posted by: Kelly      Read more         Source

December 15, 2010, 7:09 AM CT

Light in bizarre bioluminescent snail

Two researchers at Scripps Institution of Oceanography at UC San Diego have provided the first details about the mysterious flashes of dazzling bioluminescent light produced by a little-known sea snail.

Dimitri Deheyn and Nerida Wilson of Scripps Oceanography (Wilson is now at the Australian Museum in Sydney) studied a species of "clusterwink snail," a small marine snail typically found in tight clusters or groups at rocky shorelines. These snails were known to produce light, but the scientists discovered that rather than emitting a focused beam of light, the animal uses its shell to scatter and spread bright green bioluminescent light in all directions.

The researchers, who describe their findings in the Dec. 15 online version of Proceedings of the Royal Society B (Biological Sciences), say the luminous displays of Hinea brasiliana could be a deterrent to ward off potential predators by using diffused bioluminescent light to create an illusion of a larger animal.

In experiments conducted inside Scripps' Experimental Aquarium facility, Deheyn documented how H. brasiliana set off its glow, which he likens to a burglar alarm going off, when the snail was confronted by a threatening crab or a nearby swimming shrimp.

Wilson collected the snails used in the study in Australia and collaborated with Deheyn to characterize the bioluminescence......... Posted by: Kelly      Read more         Source

December 13, 2010, 7:00 AM CT

How vultures colonize the Canary Islands

The Egyptian vulture population of the Canary Islands was established following the arrival of the first human settlers who brought livestock to the islands. A genetic comparison of Iberian and Canarian birds, reported in the open access journal BMC Evolutionary Biology, observed that the Egyptian vulture population in the Canary Islands was likely established around 2500 years ago around the same time as humans began to colonise the islands.

Rosa Agudo worked with a team of scientists from the Doana Biological Station, Seville, Spain, to investigate genetic and morphological changes between 143 Iberian birds and 242 from Fuerteventura, one of the Canary Islands. She said, "We observed that the island vultures are significantly heavier and larger than those from Iberia. The establishment of this insular population took place some 2500 years ago, matching the date of human colonization. Our results suggest that human activity can trigger divergent evolution and that this process may take place on a relatively brief time scale".

The authors suggest that before the arrival of humans, the Canary Islands would not have been able to support vultures, as food resources would have been scarce, consisting only of the remains of seabirds and sea mammals, or of rodents. They say, "The introduction of new and abundant food sources by humans could have allowed not only colonization by vultures, but also their demographic expansion and their putative adaptation to the new island environment". For once, human activity has actually assisted in the diversification and adaptation of the Egyptian vulture, now globally threatened and classified as 'Endangered' on the IUCN Red List......... Posted by: Kelly      Read more         Source