Eating less healthy fish may contribute to America's stroke belt

ScienceDaily (Dec. 23, 2010) — People living in the "stroke belt" states eat more fried fish than people living in the rest of the country, which may contribute to the high rate of death from stroke in those states, according to a study published in the Dec. 22, 2010, online issue of Neurology®, the medical journal of the American Academy of Neurology.

Studies have shown that the omega-3 fatty acids in fish, especially fatty fish, may reduce the risk of stroke. Research has shown that frying fish leads to the loss of the natural fatty acids.

The study also found that African-Americans and people living in the stroke belt eat more fried fish than Caucasians and people living in the rest of the country. The stroke belt includes the states of North Carolina, South Carolina, Georgia, Alabama, Mississippi, Tennessee, Arkansas, and Louisiana. People living in the stroke belt are more likely to die from a stroke than people living in other parts of the country.

"These differences in fish consumption may be one of the potential reasons for the racial and geographic differences in stroke incidence and mortality," said study author Fadi Nahab of Emory University in Atlanta and a member of the American Academy of Neurology.

The study involved 21,675 people participating in the Reasons for Geographic And Racial Differences in Stroke (REGARDS) study, with an average age of 65. Of the participants, 21 percent were from the "stroke buckle," which is the coastal plain region of North Carolina, South Carolina and Georgia with stroke mortality rates even higher than in the rest of the stroke belt. Another 34 percent were from the rest of the stroke belt and 44 percent were from the other 40 contiguous states.

Participants were interviewed by phone and then given an in-home physical examination. They took a questionnaire asking how often they ate oysters, shellfish, tuna, fried fish and other fish not fried.

In the entire study, fewer than 1 in 4 participants consumed two or more servings of non-fried fish per week. The American Heart Association recommends that people eat fish at least two times per week with an emphasis on fatty fish. Those in the stroke buckle were 11 percent less likely to meet the recommendations than those in the rest of the country. Those in the rest of the stroke belt were 17 percent less likely than those in the rest of the country.

African-Americans were more than three-and-a-half times more likely to eat two or more servings of fried fish per week than Caucasians, with an overall average of 0.96 servings per week of fried fish for African-Americans compared to 0.47 servings for Caucasians.

Those in the stroke belt were 30 percent more likely to eat two or more servings of fried fish than those in the rest of the country. Those in the rest of the stroke buckle were 17 percent more likely to eat two or more servings of fried fish. Overall, those in the stroke belt ate an average of 0.68 servings per week, compared to 0.64 in the stroke buckle and 0.62 in the rest of the country. For non-fried fish, those in the stroke belt ate an average of 1.45 servings per week, compared to 1.52 servings in the stroke buckle and 1.63 servings in the rest of the country.

The study was supported by the National Institute of Neurological Disorders and Stroke, the National Institutes of Health, and the Department of Health and Human Services. Funding was provided by General Mills for coding of the food frequency questionnaire.

The REGARDS study enrolled participants across the United States, age 45 or older, between January 2003 and October 2007.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Academy of Neurology.

Journal Reference:

F. Nahab, A. Le, S. Judd, M.R. Frankel, J. Ard, P.K. Newby, V.J. Howard. Racial and geographic differences in fish consumption: The REGARDS Study. Neurology, 2010; DOI: 10.1212/WNL.0b013e3182061afb

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Invasive species pose major threat to fish in Mediterranean basin, large-scale study finds

ScienceDaily (Nov. 15, 2010) — An international team led by the Forest Technology Centre of Catalonia has carried out the first large-scale study of the threats facing freshwater fish in the Mediterranean basin. Invasive species, along with over-exploitation of water resources, are the most important pressures, and those that expose fish to the greatest risk of extinction.

"The continental fish of the Mediterranean basin are one of the most threatened biological groups in the world," says Miguel Clavero, lead author of the study and a researcher from the Landscape Ecology Group of the Forest Technology Centre of Catalonia.

The study, which has been published in the journal Diversity and Distributions, looks at the geographical distribution of the manmade factors (pressures) with a negative impact on biodiversity and their relationship to the degree of threat faced by endemic freshwater fish communities in the Mediterranean basin. The study combined information on the pressures affecting 232 fish species and their distribution range.

"The Iberian Peninsula is one of the areas in which invasive species have the greatest impact on native fish," explains Clavero. His team has studied the commonest pressures, such as pollution, water extraction, invasive species, reservoirs, agriculture and over-fishing.

By relating the distribution of these pressures with the degree of threat faced by the fish in each area, the researchers have shown that "fish communities are exposed to the greatest threat of extinction when the most significant pressures are the impact of invasive species and over-exploitation of water resources," the expert says.

Clavero says "these two pressures are the leading causes of biodiversity loss among continental fish in the Mediterranean region." The results bear out those of other studies on a smaller geographic scale carried out in various parts of the Mediterranean.

"We also have notorious examples in Spain of the negative effects of the over-exploitation of water resources, as is the case in the upper basin of the Guadiana (including the Tablas de Daimiel wetlands)," the scientist adds.

The biggest analysis of the Mediterranean basin

The research team compiled the information evaluating the conservation status of endemic continental fish species in the Mediterranean basin drawn up by the International Union for the Conservation of Nature (IUCN) Centre for Mediterranean Cooperation.

The scientists calculated the number of fish species affected by each type of pressure in 10x10 km areas in the Mediterranean basin. "This allowed us to describe the geographical variation in the impacts caused by the various pressures, which could then be related to the extinction risk for the fish communities," explains Clavero.

The team used data on two geographical scales (aside from the 10x10 km areas, they also analysed complete river basins), as well as two complementary indicators on extinction risk, based on the IUCN categories of threat.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Plataforma SINC, via AlphaGalileo.

Journal Reference:

Miguel Clavero, Virgilio Hermoso, Noam Levin, Salit Kark. Geographical linkages between threats and imperilment in freshwater fish in the Mediterranean Basin. Diversity and Distributions, 2010; 16 (5): 744 DOI: 10.1111/j.1472-4642.2010.00680.x

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Ecologists get fish eye view of sexual signals

ScienceDaily (Nov. 9, 2010) — Carotenoid pigments are the source of many of the animal kingdom's most vivid colours; flamingos' pink feathers come from eating carotenoid-containing shrimps and algae, and carotenoid colours can be seen among garden birds in blackbirds' orange beaks and blue tits' yellow breast feathers.

These pigments play a crucial role in sexual signals. According to the study's lead author Dr Tom Pike of the University of Exeter: "Females typically use carotenoid colours to assess the quality of a potential mate, with more colourful males generally being regarded as the most attractive."

This long-held assumption is, however, hard to study because we see colour very differently to fish and previous studies have not taken such differences into account, instead comparing only the colours perceived by humans.

"The major difference between stickleback vision and our own is that they can see ultraviolet light, which is invisible to humans. This may be important because carotenoids reflect ultraviolet light as well as the red, oranges and yellows that we can see," Dr Pike explains.

The model developed by Dr Pike and colleagues from the University of Glasgow and Nofima Marine in Norway mimics the stickleback's visual system, allowing the researchers to determine what 'colours' the fish see. "The model tells us how much of the light reflected from a carotenoid signal is actually detected by a female and how this information might be processed by her brain, and so gives us exciting new insights into how females may use colour to choose the best mates," says Dr Pike.

Male sticklebacks can fine tune the colours they display to females by varying both the overall amount of carotenoids and the relative amount of the two constituent carotenoids, the red-coloured astaxanthin and the yellow tunaxanthin. The model reveals that sticklebacks' visual system and coloration are extremely well co-adapted, and that females are surprisingly good at assessing the quantity of carotenoids a male is able to put in his signal -- which previous studies by the authors have shown is linked to his parenting ability.

The results will help ecologists get a better understanding of why carotenoid-based signals evolved in the first place, and provides insights into why males use the specific carotenoids they do. According to Dr Pike: "There are many carotenoids in the sticklebacks' diet, but males use only two of them for signalling; because the visual system evolved long before male coloration in this species, it suggests that males 'chose' to use those two carotenoids to make the most of what the female fish sees."

The study was funded by the UK's Natural Environment Research Council (NERC).

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Wiley-Blackwell, via EurekAlert!, a service of AAAS.

Journal Reference:

Thomas W. Pike, Bj?rn Bjerkeng, Jonathan D. Blount, Jan Lindstr?m, Neil B. Metcalfe. How integument colour reflects its carotenoid content: a stickleback’s perspective. Functional Ecology, 2010; DOI: 10.1111/j.1365-2435.2010.01781.x

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New large squid found in southern Indian Ocean

ScienceDaily (Nov. 15, 2010) — A new species of squid has been discovered by scientists analyzing 7,000 samples gathered during last year's IUCN-led seamounts cruise in the southern Indian Ocean.

The new species, 70 centimeters long, is a large member of the chiroteuthid family -- squids from this group are long and slender with light-producing organs, which act as lures to attract prey. So far, more than 70 species of squid have been identified from the seamounts cruise, representing more than 20 percent of the global squid biodiversity.

"For ten days now 21 scientists armed with microscopes have been working through intimidating rows of jars containing fishes, squids, zooplankton and other interesting creatures," says Alex Rogers, of the Department of Zoology, University of Oxford. "Many specimens look similar to each other and we have to use elaborate morphological features such as muscle orientation and gut length to differentiate between them."

The recent discoveries are part of an IUCN-led Seamounts Project, which started a year ago when a team of the world's leading marine experts ventured into a six-week research expedition above seamounts in the high seas of the Indian Ocean. The aim of the cruise was to unveil the mysteries of seamounts in the southern Indian Ocean and to help improve conservation and management of marine resources in the area.

"The new discoveries will not only satiate the appetite of scientists working in the field, but will help improve conservation and management of Indian Ocean resources and future management of deep-sea ecosystems in the high seas globally," says Carl Gustaf Lundin, Head, IUCN Global Marine Programme.

To read the seamounts blog and see the photos, visit: http://seamounts2009.blogspot.com/

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by IUCN-International Union for Conservation of Nature.

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Special skin keeps fish species alive on land

ScienceDaily (Nov. 10, 2010) — A new study shows how an amphibious fish stays alive for up to two months on land. It's all in the skin.

Mangrove killifish are small fish -- only about an inch or two long -- that live in temporary pools in the coastal mangrove forests of Central and South America and Florida. During dry seasons when their pools disappear, the fish hole up in leaf litter or hollow logs. As long as they stay moist, they can survive for extended periods out of water by breathing air through their skin. But oxygen isn't the only thing a fish out of water needs to worry about, according to Professor Patricia Wright, a biologist from the University of Guelph, Ontario, who has studied these fish for years.

"All cells in the body need the right combination of ions and water for an animal to stay alive," Wright explains. "Normally, the gills are responsible for these processes in fish. We knew that in mangrove killifish the gills are likely useless on land, so how these fish maintain ion balance out of water was a mystery."

Wright's latest research, published in the November/December 2010 issue of the journal Physiological and Biochemical Zoology, shows that the skin of the mangrove killifish picks up the slack for the gills.

Through a series of laboratory experiments, Wright and her team found special cells called ionocytes clustered on the skin of the fish. Ionocytes, normally found on the gills of other fish, are the cells responsible for maintaining the right balance of water and salt in a fish's cells.

"We found the mangrove killifish have roughly as many ionocytes on their skin as on their gills," Wright said. Other fish species have skin ionocytes in larval stages of development, but usually these cells disappear in the skin as the fish develops.

To show that these skin ionocytes were doing the job, the researchers took some mangrove killifish out of water for a period of 9 days. During that time, the fish were left on a surface moist with water containing a radioactive isotope. The researchers found that the isotope eventually turned up in the fish's body.

"It's very clear they're exchanging ions through the skin," Wright said.

The skin of the mangrove killifish is also equipped to help the fish deal with varying salinity, the research found. When out-of-water fish were placed on a surface moist with salt water, the skin ionocytes got bigger, indicating that they're working overtime to keep the right salt balance. When those fish were placed back in water, the skin ionocytes returned to normal size.

It's adaptations like this, Wright says, that make this fish special -- even among amphibious fish. Lungfish, for example, need to alter their physiological state to live out of water. But with its special skin, mangrove killifish can maintain all of their normal physiological processes at nearly the same level as being in water -- and they can do it for over 60 days.

"They really are very interesting little animals," Wright said.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Chicago Press Journals.

Journal Reference:

Danielle M. LeBlanc, Chris M. Wood, Douglas S. Fudge, Patricia A. Wright. A Fish Out of Water: Gill and Skin Remodeling Promotes Osmo- and Ionoregulation in the Mangrove KillifishKryptolebias marmoratus. Physiological and Biochemical Zoology, 2010; : 000 DOI: 10.1086/656307

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Oceanography researchers discover toxic algae in open water

ScienceDaily (Nov. 13, 2010) — Louisiana State University's Sibel Bargu, along with her former graduate student Ana Garcia, from the Department of Oceanography and Coastal Sciences in LSU's School of the Coast & Environment, has discovered toxic algae in vast, remote regions of the open ocean for the first time.

The findings were published in the Nov. 8 edition of the Proceedings of the National Academy of Sciences (PNAS).

Harmful algal blooms, or HABs, are reported as increasing both geographically and in frequency along populated coastlines. Bargu's research shows that the ubiquitous diatom Pseudo-nitzschia -- an alga that produces the neurotoxin, domoic acid, or DA, in coastal regions -- actually also produces DA at many locations in the open Pacific. The presence of these potent toxins in deep water environments is worrisome, given that in coastal waters, where the phenomenon has been studied, DA can enter the food chain, forcing the closure of some fisheries and poisoning marine mammals and birds that feed on the contaminated fish. The main concern, though, is that the adding of iron to ocean waters -- one of the most commonly proposed strategies to reduce global warming -- appears now to likely result in promoting toxic blooms in the ocean.

Because both natural and artificial iron additions in open ocean waters can result in phytoplankton blooms in large areas of the sea that are deficient in the metal, and also because phytoplankton take up carbon dioxide and iron in addition to seawater, it has been suggested as a remedy to combat global warming. Basically, the new growth of photosynthetic cells draws carbon dioxide into the sea, reducing the amount of this gas in the atmosphere and thus reducing its warming effect. However, Pseudo-nitzschia-like cells have been known for a while to be common responders in a number of iron fertilization experiments conducted at sea over more than a decade.

To address the possible presence of the neurotoxin DA in regions where Pseudo-nitzschia occur in the open ocean, Bargu and one of the paper's co-authors, Mary Silver from University of California, Santa Cruz, or UCSC, sought and received funding in 2007 from National Science Foundation to look for the toxin producers in the open sea. They joined Ken Bruland, professor of ocean Sciences at UCSC, on a research cruise to study iron chemistry in oceanic waters of the Gulf of Alaska. During this expedition, they collected water samples and found the algae and its toxin in nearly all of the natural oceanic environments throughout the region. This prompted them to examine older, stored samples from other sites around the Pacific, and again they found the toxin in most samples.

Then, with the help of Kenneth Coale, director of Moss Landing Marine laboratories and principal investigator on several cruises that conducted classic iron enrichment experiments in the Pacific, they retrieved samples and found both Pseudo-nitzschia and substantial amounts of toxin. Their findings show that iron enrichment indeed promotes high levels of toxins in the open sea, sometimes as high as those in coastal regions, where deaths of seabirds and mammals occur. The authors of this PNAS paper also noted that iron enrichments can occur naturally, suggesting that the high levels of toxins may also have occurred when iron was added by wind-blown dust and other climate and geological processes.

Bargu, a principal investigator on the Gulf of Alaska phytoplankton study, was responsible for identification of all the Pseudo-nitzschia species and the toxin testing in the project. In addition to Bargu and her former graduate student Garcia, the coauthors of the PNAS paper include Silver, Coale, Ken Bruland, Susan Coale and Kathryn Roberts at UCSC; and Claudia Benitez-Nelson and Emily Sekula-Wood at the University of South Carolina. This research was funded by the National Science Foundation, U.S. Department of Energy and the U.S. Office of Naval Research.

Impacts from HABs have been also the subject of regional interest in the northern Gulf of Mexico for many decades. Among the many HAB impacts in this region, those due to coastal blooms of the diatoms genus Pseudo-nitzschia and the associated DA are of particular concern. Studies of Louisiana coastal and estuarine waters have documented the occurrence of toxic Pseudo-nitzschia, often at bloom concentrations with annual occurrence of spring blooms exceeding a million toxic cells per liter. Current thinking suggests the annual spring peak in Pseudo-nitzschia probably occurs in response to the spring flood of the Mississippi River.

An ongoing study by Bargu's lab is studying the extent of Pseudo-nitzschia and its toxin, finding that that DA-producing Pseudo-nitzschia are frequently present in nearshore and offshore Louisiana waters. Her research group has already detected high levels of DA in water and at moderate levels in gulf menhaden from Terrebone Bay, La., the second largest fishery in the U.S.

Bargu is specifically studying the impact of these blooms on the food web, trying to better understand the impact such algae growth can have on the next level up the food chain. She argues that it is now critical to understand the extent of toxic algal blooms in the area and their causes.

"Given our dependence on the seafood industry here, it is critical to recognize and then reduce the causes of toxic algal blooms," she said. "Only by monitoring and addressing the causes of the blooms can we safeguard our fisheries and the people who make a living working in them."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Louisiana State University.

Journal Reference:

Mary W. Silver, Sibel Bargu, Susan L. Coale, Claudia R. Benitez-Nelson, Ana C. Garcia, Kathryn J. Roberts, Emily Sekula-Wood, Kenneth W. Bruland, Kenneth H. Coale. Toxic diatoms and domoic acid in natural and iron enriched waters of the oceanic Pacific. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1006968107

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Fall bonefish census sounds warning bell that warrants careful future monitoring

ScienceDaily (Nov. 22, 2010) — This October more than 60 guides and anglers in the Florida Keys poled across the flats from Biscayne Bay to the Marquesas, assisting in the annual bonefish census. This year's count, held in extremely difficult weather with lowered visibility, was down by 25-percent from an 8-year mean estimate of 316,805 bonefish to a new low of about 240,000 bonefish, according to Professor Jerry Ault, a fisheries scientist with the University of Miami's Rosenstiel School of Marine & Atmospheric Science.

"Since 2003 we have conducted an annual bonefish census throughout the Keys," said Ault. "It provides researchers, like me, and fisheries managers with an early warning system to identify trends and population changes." This year guides saw fewer bonefish in historically productive areas, a possible reflection of real population changes coupled with differences in the coastal environment. Future counts will be looking for evidence of this as an emerging population trend.

"Bonefish are a good indicator of overall ecological health. These highly mobile fish feed on small marine organisms at the base of the food chain like shrimps, crabs and baitfish; thus, the health of the bonefish population is greatly dependent on the status of the ecosystem as a whole. A change in the population is likely to signal greater issues throughout the coastal ecosystem and provide clues that we can study and address before the situation becomes critical," Ault added.

Ault suggests that if bonefish abundance did decline in 2010, it is still too early to pinpoint the reasons. However, he points out that last winter's January extended cold wave was particularly lethal to tropical gamefish species including tarpon, snook and bonefish, and to their prey. Water temperatures dipped as low as 44oF for periods of more than 3.5 days, and killed mostly small (and young) bonefish in Biscayne and Florida Bays.

The census, conducted in collaboration with local fishermen and guides, as well as the Bonefish & Tarpon Trust (BTT), and the Florida Keys Fishing Guide Associations, is important because bonefish are a major component of Florida's $5.5 billion sport-fishing industry. Based on past results, Ault estimates each bonefish in Florida is worth about $3,500 per year to the industry or about $75,000 over its lifetime.

"We are especially grateful to the guides and anglers of the Keys who continue to work closely with us because one of the great challenges we face is the lack of long-term historical data on the Florida bonefish population," said Tom Davidson, chairman of the BTT. "The datasets we are now developing are just the beginning. We are still learning about natural variations in these dynamic systems, so we can't really be sure yet about the significance of these ups and downs. However, these types of major population fluctuations will ensure that we remain vigilant."

About the Bonefish & Tarpon Trust

Bonefish & Tarpon Trust is a non-profit, science-based conservation organization dedicated to ensuring that bonefish, tarpon, and permit populations, and the fisheries they support, remain healthy and helping to restore fisheries that have declined. BTT accomplishes this mission by funding conservation-focused research; working with local, national, and regional resource management agencies to improve regulations to protect these fisheries; and educating anglers and the public. BTT uses scientific findings to advocate for fisheries conservation and works to ensure coastal habitats used by bonefish, tarpon, and permit are protected.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Miami Rosenstiel School of Marine & Atmospheric Science.

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King crab distributions limited by temperature in the Southern Ocean

ScienceDaily (Nov. 8, 2010) — Invasions of voracious predatory crabs due to global warming could threaten the unique continental-shelf ecosystems of Antarctica, according to newly published findings.

"King crabs are ecologically important predators and form the basis of economically significant commercial fisheries," said Dr Sven Thatje, an evolutionary ecologist at the University of Southampton's School of Ocean and Earth Science (SOES), which is based at the National Oceanography Centre in Southampton.

Thatje and graduate student Sally Hall studied how water temperature influences the distributions of king crab species in the Southern Ocean, which has some of the coldest waters on Earth. The results appear in the journal Polar Biology.

King crabs are cold blooded, their body temperature being determined largely by that of the surrounding environment. Although many of them live in cold, deep-sea habitats, experiments have shown that their larvae fail to mature in water temperatures below around half a degree Celsius, even after only brief exposure.

"We tested the hypothesis that the king crab species of the Southern Ocean only thrive above a critical minimum temperature and that it is this thermal barrier that determines their biogeographical distributions in the Southern Ocean," said Thatje.

To do this, Thatje and Hall carefully studied the distribution of seventeen species of king crab living at depths between around 500 and 1600 metres in the Southern Ocean. They collated data frompublished records, museum collections, commercial fishing records, and reports from scientific research cruises. They then compared these records to water temperatures measured at a range of relevant depths and geographical latitudes.

Consistent with their hypothesis, they found that king crabs occur mostly at locations where the polar water temperature is relatively warm. The coldest waters in which king crabshave been found are between 0.4 and 0.5°C in the Ross Sea, suggesting that this indeed represents a thermal barrier limiting king crab distributions.

In addition, the records showed that only two species are endemic to waters south of 60 degrees South, suggesting that particular physiological and reproductive adaptations are required for life in the most extreme environments.

The researchers found that gaps in king crab distributions largely coincide with regions of low water temperature, although there are some anomalous absences yet to be explained.

Their findings imply that even relatively small increases in water temperature due to global warming could lead to king crabs moving into new areas.

"Rapidly increasing water temperatures observed along the West Antarctic Peninsula could allow king crabs to spread from the slope of the peninsula to the continental shelf itself," explained Hall.

This could have considerable ecological consequences. King crabs are voracious predators that crush and then feed on their prey, but they and potentially competing predators such as sharks and rays and other predatory crustaceans are largely absent on the high-Antarctic continental shelves.

"The worry is that the sudden appearance of a new predator with few competitors could threaten isolated shelf communities such as those of the Bellingshausen Sea on the west side of the Antarctic Peninsula," said Hall.

The researchers believe that their study provides a baseline against which future changes in the distribution of king crabs expected under global warming can be compared.

The study was supported by the Total Foundation (Abyss2100), the European Union's Sixth Framework Programme (FP6) Marine Biodiversity and Ecosystem Functioning (MarBEF) project, and by the Natural Environment Research Council.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by National Oceanography Centre, Southampton (UK).

Journal Reference:

Sally Hall, Sven Thatje. Temperature-driven biogeography of the deep-sea family Lithodidae (Crustacea: Decapoda: Anomura) in the Southern Ocean. Polar Biology, 2010; DOI: 10.1007/s00300-010-0890-0

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Female fish -- and humans? -- lose interest when their male loses a slugfest

ScienceDaily (Nov. 24, 2010) — You may think of your love for your mate as the noble emotion of a pure heart, but some primitive parts of your brain are taking a decidedly more pragmatic approach to the subject, according to Stanford biologists.

In experiments with African cichlid fish, the scientists discovered that when a female shows a preference for a particular male, but then witnesses him losing a fight with another male, her feelings toward him change.

Areas of the female's brain associated with anxiety showed increased activity after witnessing an altercation.

"It is the same as if a woman were dating a boxer and saw her potential mate get the crap beat out of him really badly," said Julie Desjardins, a postdoctoral researcher in biology. "She may not consciously say to herself, 'Oh, I'm not attracted to this guy anymore because he's a loser,' but her feelings might change anyhow."

"Our intuition is that this response is likely to occur under similar conditions in humans because the brain areas involved are present in all vertebrates and perform comparable functions," said Russ Fernald, a professor of biology.

Desjardins is the first author of a paper describing the research, to be published online by the Proceedings of the National Academy of Sciences. Fernald and Jill Klausner, a recent honors biology graduate whose thesis was on this topic, are coauthors.

Desjardins said that with people, the subconscious change of heart would likely happen in response to a failure in any competitive situation -- whether it's losing at a game or missing out on a promotion at work -- not just a brawl. She said that men might also feel differently after seeing a "female of interest" fail at something competitive.

But all is not necessarily lost for the loser -- at least not the human one.

All is not lost for the loser

We can take heart, she said, because we have so much more cognitive ability than fish and can reason our way out of these subtle twinges of doubt. And not all pair-bonding relationships are equal.

"Obviously, long-term committed relationships are very different than, say, people who have just started dating, or are in the initial phases of mate choice," Desjardins said. So losing a game of beer pong may -- or may not -- have relationship-ending consequences.

Among the fish, the researchers also found that when the preferred male prevailed, the female showed increased excitation in parts of the brain associated with reproduction, as well as some of the brain's pleasure centers.

"In this case, she is turning on her body to get ready to physically mate with this male that she previously chose," Desjardins said. The female also appears to be feeling some sort of pleasurable stimulus in her body, she said.

Desjardins said that while humans may reason beyond the sort of gut reactions displayed in the female cichlids, the human version of the brain regions involved in the fishes' decisions probably play a major role in the snap judgments men and women make.

"You may not know immediately why you are attracted to a certain person, for example," she said. "But it is these sorts of unconscious internal reflexes that we have that are shared with all vertebrates, including fish, that make us feel one way or another before we've even had time to think about it."

These same areas of the brain also probably play a part in other types of reflexive responses, such as a mother's instinct to protect her child.

Fishy flirtation

Desjardins and her colleagues conducted their experiments using a fish tank split into three sections by transparent barriers. In the middle section, they put the female, with a male in each tank on either side of her. The males were always of comparable size and weight -- as similar as possible.

For two days in a row, for 20 minutes a day, they placed the same three fish in the same three sections of the tank.

The female would typically swim around for a while, then settle down and interact with the male she preferred.

"We know that she prefers a particular male because she will display some mating behavior and he will try to do the same on his side," Desjardins said. Once a female had chosen, she never wavered -- until the fight.

On the third day, the researchers took one of the male fish and put him into the compartment of the other male fish. Cichlid males are highly territorial, so fighting ensued instantly.

Piscine pugilism

"In this fish species, fighting means a lot," Desjardins said. "When you fight with a neighbor, you not only physically fight with them, you are also displaying your abilities and your prowess to everyone watching."

The fishy fisticuffs were allowed to continue for 20 minutes, while the female watched. After that time, the researchers knew the female's brain would show clear evidence of her reaction.

Desjardins said that when they dissected a female's brain, they invariably found strong evidence of heightened activity that corresponded with whether the fish's preferred potential mate had won or lost. The researchers ran the experiment with 15 different females.

"I was extremely surprised by how large a difference in brain activity we were able to measure," Desjardins said. "To an outside observer like me, it always looked like the same thing -- two similar fish fighting. But to the females, it meant something very different."

Because the female fish had to be dissected in order to assess the activity in their brains, the researchers weren't able to test whether the females' reactions to the fights carried over into influencing their actual mating behavior.

But, Desjardins said, "Now that we know the females consistently react to the fights so strongly, we should be able to answer the burning question, "Will she really dump the loser she used to like in favor of the winner?"

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University. The original article was written by Louis Bergeron.

Journal Reference:

Julie K. Desjardins, Jill Q. Klausner, Russell D. Fernald. Female genomic response to mate information. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1010442107

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Depression-like behavior identified in zebrafish; Inability to cope with stress may play role in depression

ScienceDaily (Nov. 18, 2010) — Disrupting the stress response in zebrafish generates behaviors that resemble depression, according to new research presented at Neuroscience 2010, the annual meeting of the Society for Neuroscience, held in San Diego.

"Our findings offer a molecular basis for the intuition that long-term emotional well-being depends on an individual's ability to cope with stress," said Herwig Baier, PhD, of the University of California, San Francisco, who led the study.

Zebrafish are popular model systems in many areas of biomedical research, but this is the first discovery of a zebrafish mutant with an apparent psychiatric disorder. When faced repeatedly with a stressful situation -- isolation from others -- the mutant fish stop swimming and hide in the corner of the tank for many minutes. This abnormal behavior was reversed by bathing the fish in water containing fluoxetine (Prozac), a selective serotonin reuptake inhibitor (SSRI) commonly prescribed for people with depression.

Baier and his colleagues found that the "depressed" zebrafish had a genetic mutation in the glucocorticoid receptor (GR) gene. One of the functions of GR is to "dial down" the secretion of stress hormones from the brain. Both too much and too little GR activity has been implicated in depression. The zebrafish mutant had little to no GR activity.

"We do not know yet if all this also holds true for people. But if it does, then strategies aimed at finding new antidepressant therapies should try to resurrect, rather than block, GR activity," Baier said.

Research was supported by the National Institutes of Health.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Society for Neuroscience.

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Scientists question widely adopted indicator of fisheries health and evidence for 'fishing down marine food webs'

ScienceDaily (Nov. 18, 2010) — The most widely adopted measure for assessing the state of the world's oceans and fisheries led to inaccurate conclusions in nearly half the ecosystems where it was applied according to new analysis by an international team led by a University of Washington fisheries scientist.

"Applied to individual ecosystems it's like flipping a coin, half the time you get the right answer and half the time you get the wrong answer," said Trevor Branch, a UW assistant professor of aquatic and fishery sciences.

In 1998, the journal Science published a groundbreaking paper that was the first to use trends in the trophic levels of fish that were caught to measure the health of world fisheries. The trophic level of an organism shows where it fits in food webs, with microscopic algae at a trophic level of one and large predators such as sharks, halibut and tuna at a trophic level of around four.

The 1998 paper relied on four decades of catch data and averaged the trophic levels of what was caught. The authors determined those averages were declining over time and warned we were "fishing down the food web" by overharvesting fish at the highest trophic levels and then sequentially going after fish farther down the food web.

Twelve years later, newly compiled data has emerged that considers such things as the numbers and types of fish that actually live in these ecosystems, as well as catch data. An analysis in the Nov. 18 issue of Nature reveals weaknesses in assessing ecosystem health from changes in the trophic levels of what is being caught.

"This is important because that measure is the most widely adopted indicator by which to determine the overall health of marine ecosystems," said Branch, lead author of the new analysis in Nature. Those involved with the U.N.'s Convention on Biological Diversity, for instance, chose to use the average trophic level of fish being caught as the main measure of global marine diversity.

An example of the problem with the measure is in the Gulf of Thailand, where the average trophic level of what is being caught is rising, which should indicate improving ecosystem health according to proponents of that measure. Instead, it turns out fish at all levels have declined tenfold since the 1950s because of overharvesting.

"The measure only declines if fisheries aimed for top predators first, but for the Gulf of Thailand the measure fails because fisheries first targeted mussels and shrimps near the bottom of the food web, before shifting to predators higher up in the food web," Branch said.

Including the Gulf of Thailand, Branch found that changes in the average trophic levels of what was being caught and what was found when fish populations were surveyed differed in 13 of the 29 trawl surveys from 14 ecosystems. Trawl surveys, generally done from research vessels, count the kinds and abundance of fish and are repeated over time to reveal trends.

Branch and his co-authors are the first to combine so many trawl surveys for analysis -- no one had combined more than a handful before. The trawl survey data came from efforts started three years ago by fisheries scientists and ecologists gathered at the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. They brought together worldwide catch data, stock assessments, scientific trawl surveys, small-scale fishery data and modeling results. What emerged is the most comprehensive set of data yet for fisheries researchers and managers.

It paints a different picture from previous catch data and has revealed another major new finding: On a global scale humans don't appear to be fishing down the food web, Branch said.

The new catch data reveal that, following declines during the 1970s in the average trophic levels of fish being caught, catches of fish at all trophic levels have generally gone up since the mid-80s. Included are high-trophic predators such as bigeye tuna, skipjack tuna and blue whiting.

"Globally we're catching more of just about everything," Branch said. "Therefore relying on changes in the average trophic level of fish being caught won't tell us when fishing is sustainable or if it is leading to collapse." That's because when harvests of everything increase about equally, the average trophic level of what is caught remains steady. The same is true if everything is overfished to collapse. Both scenarios were modeled as part of the Nature analysis.

"The 1998 paper was tremendously influential in gathering together global data on catches and trophic levels and it warned about fishing impacts on ecosystems," Branch says. "Our new data from trawl surveys and fisheries assessments now tell us that catches weren't enough. In the future we will need to focus our limited resources on tracking trends in species that are especially vulnerable to fishing and developing indicators that reflect fish abundance, biodiversity and marine ecosystem health. Only through such efforts can we reliably assess human impacts on marine ecosystems."

"In this paper we conducted the first large-scale test of whether changes in the average trophic levels of what is caught are a good indicator of ecosystem status," says Beth Fulton, a co-author and ecosystem modeler with the Commonwealth Scientific and Industrial Research Organisation, Australia. "Catch data might be easiest to get, but that doesn't help if what it tells us is wrong. Instead we really need to look directly at what the ecosystems are doing."

Other co-authors are Reg Watson and Grace Pablico, University of British Columbia; Simon Jennings, Centre for Environment, Fisheries and Aquaculture Science and University of East Anglia, England; Carey McGilliard, University of Washington; Daniel Ricard, Dalhousie University in Halifax, Nova Scotia; and Sean Tracey, University of Tasmania, Australia.

The work was supported by the National Science Foundation, Gordon and Betty Moore Foundation and the UW School of Aquatic and Fishery Sciences. It used data from the National Center for Ecological Analysis and Synthesis working group, used the stock assessment database funded by the Canadian Natural Sciences and Engineering Research Council and the Canadian Foundation for Innovation and used data from the Sea Around Us project funded by Pew Charitable Trust.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Washington.

Journal References:

Trevor A. Branch, Reg Watson, Elizabeth A. Fulton, Simon Jennings, Carey R. McGilliard, Grace T. Pablico, Daniel Ricard, Sean R. Tracey. The trophic fingerprint of marine fisheries. Nature, 2010; 468 (7322): 431 DOI: 10.1038/nature09528D. Pauly. Fishing Down Marine Food Webs. Science, 1998; 279 (5352): 860 DOI: 10.1126/science.279.5352.860

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A love game: Fish courtship more complex than thought

ScienceDaily (Nov. 12, 2010) — Monash University researchers have discovered that male Australian desert goby fish are surprisingly strategic when it comes to courtship, adapting their tactics depending on the frequency of their contact with females.

Attracting females involves significant time, energy and exposure to predation and previous research has indicated that male gobies are more likely to court larger females due to the number of eggs they carry compared with their smaller counterparts.

However, new research, published in the journal Behavioral Ecology and Sociobiology, indicates that should the male fish find himself infrequently in contact with females, he will pursue any he finds with zeal, regardless of size.

Doctors Andreas Svensson, Topi Lehtonen and Bob Wong expanded on their previous research by procuring goby fish from Central Australia and monitoring their behaviour under controlled conditions in a laboratory.

Dr Bob Wong, a Senior Lecturer in the Science Faculty at Monash University, said the research showed that when males encountered females more frequently, the males were far more discriminating about how much effort they put into courting larger females over others.

"By contrast, males will court females vigorously irrespective of her attractiveness if passing females are few and far between," Dr Wong said.

Native to the springs and waterholes of the arid regions surrounding Lake Eyre, the desert goby is an unusual species.

Dr Wong said the male goby fish establish nests under rocks, try to attract passing females using colourful courtship displays and ultimately become the sole guardians of the eggs.

"Given this heavy investment in reproduction, males attempt to maximise their returns through higher egg yields," Dr Wong said.

"These findings are important because, for a long time, females were typically regarded as the more discerning sex when it comes to choosing a potential mate. Here, we show that males, too, can be highly picky and are much more tactical in whom they choose to court," Dr Wong said.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Monash University.

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Scientists question fisheries health test

ScienceDaily (Nov. 23, 2010) — The findings – published this week in Nature – followed an examination of  whether changes in fishery catches reflect changes in the structure of marine food webs, and therefore are a suitable guide to assess the impacts of fishing on marine ecosystem health.

published this week in Nature – followed an examination of  whether changes in fishery catches reflect changes in the structure of marine food webs, and therefore are a suitable guide to assess the impacts of fishing on marine ecosystem health.

CSIRO Wealth from Oceans Flagship scientist, Dr Beth Fulton, and Dr Sean Tracey from the Tasmanian Aquaculture and Fisheries Institute at the University of Tasmania, were members of the international team involved in the study.

“Biodiversity indicators are used to track the impacts of fishing as a guide to management effectiveness,” Dr Fulton said.

“The most widely adopted indicator of biodiversity in the ocean at a global scale is the ‘average trophic level’ (position in the food chain) determined from fishery catches.

“This is intended to detect shifts from high-trophic-level predators such as Atlantic cod and tunas to low-trophic-level fish, invertebrates and plankton-feeders such as oysters.”

Dr Tracey said the study was the first large-scale test of whether average trophic level determined by fishery catch is a good indicator of ecosystem average trophic level, marine biodiversity and ecosystem status.

“We looked at average trophic level determined from a range of sources including global fishery catches, long-term surveys, stock assessments and complex computer modelling for marine ecosystems around the world,” Dr Tracey said.

“In contrast to previous findings, which reported declines in catch average trophic level thought to be due to the loss of large fish and the increasing catch of small fish, we found that catches are increasing at most levels of marine food webs and that the average trophic level has actually increased in the past 25 years.

“We also found that average trophic level determined from fishery catches does not reliably measure the magnitude of fishing impacts or the rate at which marine ecosystems are being altered by fishing.”

Dr Tracey says global fisheries are at a crucial turning point, with high fishing pressure being offset in some regions by rebuilding efforts. Relying on the average trophic level of catch could mislead policy development.

Dr Fulton said that, to target limited resources in the best way, researchers should focus on assessing species vulnerable to fishing that are not currently assessed effectively

“We also need to develop and expan trend-detection methods that can be applied more widely, particularly to countries with few resources for science and assessment.

“Through such efforts we can better detect and convey the true impact of fisheries on marine biodiversity,” Dr Fulton said.

Led by University of Washington fisheries scientist, Trevor A. Branch, the study’s findings are published in a letter in Nature entitled: “The trophic fingerprint of marine fisheries”.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by CSIRO Australia.

Journal Reference:

Trevor A. Branch, Reg Watson, Elizabeth A. Fulton, Simon Jennings, Carey R. McGilliard, Grace T. Pablico, Daniel Ricard, Sean R. Tracey. The trophic fingerprint of marine fisheries. Nature, 2010; 468 (7322): 431 DOI: 10.1038/nature09528

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Boa constrictors can have babies without mating, new evidence shows

ScienceDaily (Nov. 4, 2010) — In a finding that upends decades of scientific theory on reptile reproduction, researchers at North Carolina State University have discovered that female boa constrictors can squeeze out babies without mating.

More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.

Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.

This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.

The study is published online in Biology Letters, a Royal Society journal.

Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.

Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.

Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.

It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.

"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."

A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.

Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by North Carolina State University.

Journal Reference:

Warren Booth, Coby Schal, Edward L. Vargo Daniel H. Johnson and Sharon Moore. Evidence for viable, non-clonal but fatherless Boa constrictors. Biololgy Letters, November 3, 2010 DOI: 10.1098/rsbl.2010.0793

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Rare cold water coral ecosystem discovered off coast of Mauritania

ScienceDaily (Nov. 15, 2010) — From previous research projects, Professor André Freiwald, head of the marine research department (Senckenberg am Meer, Wilhelmshaven) already had an idea of the extent of the cold water coral bank which, on the basis of previous knowledge, was located unusually far to the south. Now the Senckenberg scientist reports from on board the Maria S. Merian research ship that a cold water coral reef with living animals has been discovered off the coast of Mauritania. In the middle of the enormous rock formation of the undersea canyon area, the scientists also stumbled across the giant deep sea oyster, a Methuselah among sea creatures.

The coral wall on the continental shelf off the coast of Mauritania measures 50 to 60 m high and is 190 km long. When the Swedish robot pilot Tomas Lund?lv of the Sven Lovén Centre of the University of Gothenburg set down a diving robot on the seafloor at a depth of 615 m, the scientist on board the research ship found himself via a video link in the middle of a flourishing coral ecosystem. André Freiwald reports on a heavily calcified Lophelia coral with orange-red polyps and gorgonias, which, beside the reef-building stony corals, formed imposing octocoral gardens in the dark and otherwise inaccessible habitat. According to the excited expedition report, giant clams also hang on the coral galleries, in exactly the same way as is found elsewhere in Norwegian reef systems.

Such impressive ecosystems were previously only known above all from regions of the sea located much further to the north, around Scandinavia and in the Irish Sea. Unlike their tropical relatives, found by snorkellers and scuba divers in the illuminated and significantly warmer surface waters, cold water corals live at a cold 13° in the dark and nutrient-rich deep sea region below 200 m. André Freiwald was aware of a loose cold water coral reef which extends to southern regions. Until now, however, scientists had only found fossil coral reef structures on the seafloor off the coast of Gibraltar and Morocco.

While the Maria S. Merian, equipped with a dynamic positioning system, accompanied the diving robot step by step, the on-board coral team followed the exploratory dive, around 60 km west of Cape Tamirist, which took them into absolutely uncharted waters. Meter by meter, the device worked its way up the slope following a navigation chart drawn up by the Senckenberg scientist, Dr. Lydia Beuck, when at a depth of approximately 500 m, the coral group discovered further Lophelia colonies in a bizarre rock formation which nevertheless have a significantly more fragile development of calcification. In his report, André Freiwald writes that at the same time, the diversity of sponges and large crustaceans at the location increased significantly. Among other things, the scientists found the powerful carrier crab Paromola here, and on diving through the rocky landscape, also found the giant deep sea oyster Neopycnodonte, also never before observed so far to the south. These giant oysters form thick populations and can be described as Methuselahs among animals, with some individuals living for over 500 years.

For the scientists on board the Maria S. Merian, the discovery of the ecosystem with living cold water corals came as a surprise. André Freiwald sees one reason for the southern occurrence of the anthozoans which are adapted to cold temperatures in the upwelling ocean cells steered by the Passat wind. The offshore winds push the surface waters from the Mauritanian cliffs out into the open ocean and thereby permit a following flow of cold and nutrient-rich water from the depths. This evidently not only ensures that the Mauritanian waters are among the richest of any in fish but also presumably also provides the cold water corals with appropriate feed. According to statements by coral experts, the marine creatures feed on the nutrients released by plankton organisms.

The 16th research voyage with the Maria S. Merian, under the leadership of Professor Hildegard Westphal from the Leibniz Centre for Tropical Marine Ecology in Bremen, ends on 20 November in Mindelo (Cape Verde). Until then, it will stop at and chart further parts of the coral system in the canyon of the continental shelf off the coast of Mauritania. André Freiwald expects the next dives on this expedition to provide information as to whether the newly discovered ecosystem represents a single structure or whether a spatially extended living reef province exists in the southern waters.

The samples documented and permanently fixed during the voyage by Dr. Claudia Wienberg (MARUM, University of Bremen) and the Italian expert on corals, Dr. Marco Taviani (CNR-ISMAR, Bologna) will then be further investigated in the home laboratories.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Senckenberg Research Institute and Natural History Museum, via AlphaGalileo.

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Evolution by religious selection: Mexican cavefish develop resistance to toxin

ScienceDaily (Nov. 5, 2010) — A centuries-old religious ceremony of an indigenous people in southern Mexico has led to small evolutionary changes in a local species of fish, according to researchers from Texas A&M University.

Since before the arrival of Christopher Columbus to the New World, the Zoque people of southern Mexico would venture each year during the Easter season deep into the sulfuric cave Cueva del Azufre to implore their deities for a bountiful rain season. As part of the annual ritual, they release into the cave's waters a distinctive, leaf-bound paste made of lime and the ground-up root of the barbasco plant, a natural fish toxin. Believing the cave's fish to be gifts from their gods, they scoop up their poisoned prey to feed upon until their crops are ready to harvest.

However, a team of researchers led by Dr. Michael Tobler, an evolutionary ecologist at Oklahoma State University, and Dr. Gil Rosenthal, a biology professor at Texas A&M, has discovered that some of these fish have managed not only to develop a resistance to the plant's powerful toxin, but also to pass on their tolerant genes to their offspring, enabling them to survive in the face of otherwise certain death for their non-evolved brethren.

Their findings recently were published in the online journal Biology Letters.

Tobler has been studying the small, cave-dwelling fish species known as the Atlantic molly or Poecilia mexicana and its uncanny ability to survive in the toxic sulfur environment of Cueva del Azufre since 2004. He earned his Ph.D. from the University of Zurich in 2008 and spent the next two years as a postdoctoral research associate at Texas A&M, studying under Rosenthal and Dr. Kirk Winemiller, a professor in wildlife and fisheries science, as part of a two-year, $79,000 Swiss National Science Foundation Postdoctoral Fellowship.

After learning about the Zoque people's sacred ritual and witnessing the event firsthand in 2007, Tobler and Rosenthal decided to investigate the effects of this peculiar ceremony on the mollies and their habitat. Ironically, it was the last ceremony ever held, as the Zoques ended the practice that year due to political pressure from the government, which sought to preserve the cave as a hotbed for tourism and potential revenue.

"We wanted to do a lab experiment where we exposed fish from different parts of the creek to barbasco," Tobler says. "Some of these fish had been more exposed than others."

In March 2010, the team collected molly specimens from two different areas of the cave annually exposed to the barbasco toxin as well as from two different areas upstream, further away from the Zoque's ritual. With both groups of fish in a single tank, they then introduced the barbasco root to determine how both groups would react.

They found that the mollies annually exposed to the barbasco indeed were more resistant than the fish further upstream -- to the extent that they were able to swim in the noxious water nearly 50 percent longer. Tobler and Rosenthal's group concluded that human beings had, over time, not only affected molly population dynamics, but also inadvertently kick-started the evolutionary process of natural selection as well. Mollies able to tolerate the poisonous conditions survived and passed those traits to their offspring, resigning those that perished to their fate of serving as a ceremonial feast for the Zoque.

"The cool thing is that this ceremony has gone on a long time and that the fish responded to it evolutionarily," Tobler says. "Lots of species couldn't live with these changes. It highlights how nature is affected by human activity."

Rosenthal contends that the idea of imposing evolutionary divergence on a species at an extremely localized spatial scale is not a new concept. In fact, he says, it's been happening since the beginning of humankind and that the idea of the "noble savage" is passé.

"We tend to have this wonderful Pocahontas idea that before Europeans came in, everything was pristine and in harmony with nature and that all of the changes in our environment have been post-industrialization," he explains. "No. People have been changing the environment forever."

Moreover, Rosenthal says, once a species has become genetically adapted to human presence, it is not very easy to suddenly reverse.

Their ritual since banned, the Zoques still perform a mock ceremony each Easter season. Tobler, however, would like to see the Zoque's original ceremony resume, but in a way that is sustainable to nature as well as other cave inhabitants. The key, he and Rosenthal believe, is to find a balance between human activity and their environment. In the case of the Zoques, it may mean a few limitations on barbasco usage for their ritual, such as releasing the toxin only 50-to-60 meters into the cave rather than 100 meters.

Pending further resolution, Tobler will continue his research with the mollies at Oklahoma State, where they are housed in a special tank built to safely imitate their sulfuric living conditions in Cueva del Azufre.

"We need to understand what the impact really is on these fish rather than eliminate the ceremony completely," Tobler says. "We want to hopefully find a balance between the cultural practices of these people and the ecosystem."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Texas A&M University.

Journal Reference:

M. Tobler, Z. W. Culumber, M. Plath, K. O. Winemiller, G. G. Rosenthal. An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish. Biology Letters, 2010; DOI: 10.1098/rsbl.2010.0663

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Discus fish parent young like mammalian mothers

ScienceDaily (Nov. 1, 2010) — Few fish are famed for their parenting skills. Most species leave their freshly hatched fry to fend for themselves, but not discus fish. Jonathan Buckley from the University of Plymouth, UK, explains that discus fish young feed on the mucus that their parents secrete over their bodies until they are big enough to forage. 'The parental care that they exhibit is very unusual,' says Buckley. Intrigued by the fish's lifestyle, Buckley's PhD advisor, Katherine Sloman, established a collaboration with Adalberto Val from the Laboratory of Ecophysiology and Molecular Evolution in Manaus, Brazil, and together with Buckley and Richard Maunder set up a colony of breeding discus fish to find out more about their strange behaviour.

The team published their discovery that discus fish parent their young like mammalian mothers on 29 October 2010 in The Journal of Experimental Biology.

Unfortunately, discus fish are notoriously difficult to bred and keep in captivity. 'Hobbyists didn't succeed in rearing them until the 1970s,' explains Buckley. Having imported 30 adults from breeders in Malaysia, the team reproduced the breeding conditions in the Amazon during the dry season to encourage the fish to spawn. They lowered the water level and left it for a few hours before topping the tank up with cold water, and repeated the process until the pair was ready to lay their eggs. Buckley also collected samples of the orange mucus from the fish's flanks before they spawned and at various stages after the eggs had hatched, and monitored the parent's behaviour as their offspring grew.

During the first 3 days after hatching, the fry remained attached to the cone where the parents laid their eggs, absorbing the yolk and gaining strength until all of the fry were able to swim independently. Then they left the cone en masse and began feeding on their parents' mucus, feeding for up to 10·min by biting at the parent's side until the parent expertly 'flicked' the shoal over to its partner to continue feeding. The parents diligently fed their young intensely for 2 weeks. However, 3 weeks after hatching the parents' behaviour began to change as they started swimming away from their young for brief periods. At the same time the fry began biting their parents less and investigating other food sources. By the fourth week the parents were actively swimming away from their brood for the majority of the time and the fry barely bit them at all.

'There are a lot of parallels between the discus fish's parental care and the parental care that we see in mammals and birds,' says Buckley. Initially the parents invest all of their effort in raising their current batch of young, but wean the offspring when their investment in the current brood might begin affecting later broods. Buckley suspects that he sees signs of the conflict often seen between mammals and their young -- where parents want to wean their offspring and the offspring continue pursuing them -- in the fish's chasing behaviour during the third week after hatching.

Monitoring the composition of the parents' mucus before they spawned and through to the end of their parental responsibilities, Buckley found a huge increase in the mucus's antibody and protein levels when the parents laid their eggs, similar to the changes seen in mammalian milk around the time of birth. The protein and antibody levels remained high until the third week and returned to pre-spawning levels during the fourth week after hatching. Buckley suspects that the sudden increase in protein levels at spawning is hormonally regulated, much like the changes in mammalian milk, and is keen to find out more about the hormones that regulate the fish's mucus supply as they care for their young.

This research was funded by the Leverhulme Trust.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Journal of Experimental Biology, via EurekAlert!, a service of AAAS. The original article was written by Kathryn Knight.

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Whale sharks do the math to avoid that sinking feeling

ScienceDaily (Nov. 24, 2010) — They are the largest fish species in the ocean, but the majestic gliding motion of the whale shark is, scientists argue, an astonishing feat of mathematics and energy conservation. In new research published November 25 in the British Ecological Society's journal Functional Ecology marine scientists reveal how these massive sharks use geometry to enhance their natural negative buoyancy and stay afloat.

For most animals movement is crucial for survival, both for finding food and for evading predators. However, movement costs substantial amounts of energy and while this is true of land based animals it is even more complex for birds and marine animals which travel in three dimensions. Unsurprisingly this has a profound impact on their movement patterns.

"The key factor for animal movement is travel speed, which governs how much energy an animal uses, the distance it will travel and how often resources are encountered," said lead author Adrian Gleiss from Swansea University. "However, oceanic animals not only have to consider their travel speed, but also how vertical movement will affect their energy expenditure, which changes the whole perspective."

For the past four years, Adrian Gleiss and Rory Wilson, from Swansea University, worked with Brad Norman from ECOcean Inc. to lead an international team to investigate the movements of whale sharks, Rhincodon typus, at Ningaloo Reef in Western Australia. They attached animal-borne motion sensors, accelerometers, to the free-swimming whale sharks to measure their swimming activity and vertical movement, which allowed them to quantify the energetic cost of vertical movement.

The team's data revealed that whale sharks are able to glide without investing energy into movement when descending, but they had to beat their tails when they ascended. This occurs because sharks, unlike many fish, have negative buoyancy.

Also, the steeper the sharks ascended, the harder they had to beat their tail and the more energy they had to invest. The Whale Sharks displayed two broad movement modes, one consisting of shallow ascent angles, which minimize the energetic cost of moving in the horizontal while a second characteristic of steeper ascent angles, optimized the energetic cost of vertical movement.

"These results demonstrate how geometry plays a crucial role in movement strategies for animals moving in 3-dimensions," concluded Gleiss. "This use of negative buoyancy may play a large part in oceanic sharks being able to locate and travel between scarce and unpredictable food sources efficiently."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Wiley-Blackwell, via EurekAlert!, a service of AAAS.

Journal Reference:

Adrian C. Gleiss, Brad Norman, Rory P. Wilson. Moved by that sinking feeling: variable diving geometry underlies movement strategies in whale sharks. Functional Ecology, 2010; DOI: 10.1111/j.1365-2435.2010.01801.x

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New microorganisms linked to gill disease in salmon

ScienceDaily (Nov. 15, 2010) — Gill disease may have several different causes, such as adverse environmental impacts or a variety of microorganisms. Terje M. Steinum's doctoral research has identified microorganisms that may lead to gill disease, thereby making a significant contribution to our understanding of such diseases in farmed salmon.

Gill disease poses a considerable problem to salmon farming. Disease-induced changes usually consist of massive lesions, which greatly reduce the surface area of the gills, thereby causing breathing problems which can lead to the death of the fish. These changes can have several different causes and cannot therefore be linked to one particular agent.

The main aim of the research was to identify microorganisms that are involved in gill disease by means of modern, molecular methods, combined with traditional, histopathological studies.

The results of Steinum's work indicate that two bacteria, Ca. Pisciclamydia salmonis and another species, not yet named, plus a recently discovered unicellular parasite, Desmozoon lepeophtherii, play a role in the development of the gill disease called proliferative gill inflammation.

In addition, the thesis shows that an amoeba called Neoparamoeba perurans, only recently discovered, is linked to the amoeba gill disease that was diagnosed for the first time in Norway four years ago.

Furthermore, Steinum's thesis has increased our basic knowledge through its description of other bacteria that normally occur in the gills of diseased and apparently healthy fish respectively.

This doctoral research led to the publishing of four scientific articles and was carried out at The National Veterinary Institute (VI) in collaboration with The Norwegian School of Veterinary Science (NVH) in Oslo.

Terje M. Steinum, Cand.scient, presented his doctoral thesis on 20th October 2010 at The Norwegian School of Veterinary Science. The thesis is entitled: "Microbial studies related to proliferative gill diseases in Atlantic salmon."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Norwegian School of Veterinary Science.

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To punish or not to punish: Lessons from reef fish and saber-tooth blennies

ScienceDaily (Nov. 5, 2010) — Researchers have experimentally shown that some species of reef fish will enact punishment on the parasitic saber-tooth blennies that stealthily attack them from behind and take a bite, even though their behavior offers no immediate gain. The study, published online Nov. 4 in Current Biology, a Cell Press publication, shows that punishment ultimately serves all members of the reef fish species well.

In future attacks, blennies are more likely to go after "free-riding" individuals that don't take the time or expend the energy to punish their enemies, the researchers show, suggesting that reef fish punish blennies for reasons that are self-serving. Their self-serving behavior nonetheless creates a "public good." When given a choice, blennies are more apt to switch to another species for their next attack after their previous fare has punished them.

"Our study shows that public goods may arise due to self-serving behavior and without any consideration of the benefits to other group members," said Andrea Bshary of the University of Neuchâtel in Switzerland.

Cooperation in groups can be difficult to explain, since it would seem that "free riders" would win out as they take advantage of the efforts of their peers without contributing themselves. Human studies have explained this conundrum in two ways. Those who contribute may gain from the positive reputation it affords them, which may increase others' willingness to help them at another time. Alternatively, people might cooperate if cheaters can be punished. That raises another question: When does it make sense to punish, given that punishment has immediate costs to both the punisher and the punished?

To explore that question, Bshary and her colleague Redouan Bshary turned to scalefin anthias and the blennies they are known to chase. In this case, it was clear that the reef fish couldn't be acting out of concern for their close kin, because the shoaling fish are generally unrelated to one another.

In laboratory tests, the researchers showed that blennies were less likely to target a colored Plexiglas plate that had earlier chased them off than one that didn't. This showed the chasing behavior to be a bona fide example of punishment; chasing blennies has no immediate benefit, because the parasites almost always bite once per attack. The punishment instead leads to future gains as blennies become less likely to attack punishers.

In observational studies in a natural setting, the researchers found that punishment increased the likelihood that blennies would go for another species in their next attack. This means that all members of a species win when one of them punishes a blenny. Finally, the researchers showed in experiments that at least some blennies could tell the difference between look-alike pairs of plates in which one "punished" them and the other did not, and they would selectively bite nonpunishers. As a result, free riders are at a disadvantage.

The findings in fish suggest that humans, too, might sometimes appear to work together in the real world for reasons that are directly self-serving at their core, the researchers say. They point out that their study differs in an important regard from standard tests of game theory in humans in that the blennies interacted with only one individual of their own choosing. In human experiments, people often interact in groups.

"As a consequence," the researchers write, "it is always clear which individual of a shoal has to punish the blenny for its cheating. A victim cannot expect others to do the punishment, because they did not have a negative experience. We think that such conditions often apply to humans as well, in which punishment is a self-serving response to being cheated while benefiting the community as well. A person whose house gets broken into or who gets attacked by robbers will have to take action (call the police or fight back) even though all the neighbors may profit from this."

The researchers include Andrea Bshary, and Redouan Bshary, of University of Neuchatel, Institute of Biology, Neuchatel, Switzerland.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Journal Reference:

Andrea Bshary, and Redouan Bshary. Self-Serving Punishment of a Common Enemy Creates a Public Good in Reef Fishes. Current Biology, 2010; DOI: 10.1016/j.cub.2010.10.027

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Most river flows across the US are altered by land and water management

ScienceDaily (Nov. 3, 2010) — The amount of water flowing in streams and rivers has been significantly altered in nearly 90 percent of waters that were assessed in a new nationwide USGS study. Flow alterations are a primary contributor to degraded river ecosystems and loss of native species.

"This USGS assessment provides the most geographically extensive analysis to date of stream flow alteration," said Bill Werkheiser, USGS Associate Director for Water. "Findings show the pervasiveness of stream flow alteration resulting from land and water management, the significant impact of altered stream flow on aquatic organisms, and the importance of considering this factor for sustaining and restoring the health of the Nation's streams and ecosystems."

Flows are altered by a variety of land- and water-management activities, including reservoirs, diversions, subsurface tile drains, groundwater withdrawals, wastewater inputs, and impervious surfaces, such as parking lots, sidewalks and roads.

"Altered river flows lead to the loss of native fish and invertebrate species whose survival and reproduction are tightly linked to specific flow conditions," said Daren Carlisle, USGS ecologist and lead scientist on this study. "These consequences can also affect water quality, recreational opportunities and the maintenance of sport fish populations."

For example, in streams with severely diminished flow, native trout, a popular sport fish that requires fast-flowing streams with gravel bottoms, are replaced by less desirable non-native species, such as carp. Overall, the USGS study indicated that streams with diminished flow contained aquatic communities that prefer slow moving currents more characteristic of lake or pond habitats.

"Management practices related to water demand continue to alter stream flows in many places," said Jeff Ostermiller, Water Quality Manager with the Utah Division of Water Quality. "Understanding the ecological effects of these flow alterations helps water managers develop effective strategies to ensure that water remains sufficiently clean and abundant to support fisheries and recreation opportunities, while simultaneously supporting economic development."

Annual and seasonal cycles of water flows -- particularly the low and high flows -- shape ecological processes in rivers and streams. An adequate minimum flow is important to maintain suitable water conditions and habitat for fish and other aquatic life. High flows are important because they replenish floodplains and flush out accumulated sediment that can degrade habitat.

"While this study provided the first, national assessment of flow alteration, focused studies within specific geographic regions will provide a better understanding of the ecological effects of altered stream flows, which can be more effectively applied to local water management challenges," said Carlisle.

The severity and type of stream flow alteration varies among regions, due to natural landscape features, land practices, degree of development, and water demand. Differences are especially large between arid and wet climates. In wet climates, watershed management is often focused on flood control, which can result in lower maximum flows and higher minimum flows. Extremely low flows are the greatest concern in arid climates, in large part due to groundwater withdrawals and high water use for irrigation.

The study identified over 1,000 unimpaired streams to use as reference points to create stream flow models. The models were applied to estimate expected flows for 2,888 additional streams where the USGS had flow monitoring gauges from 1980-2007. The estimated values for the 2,888 streams were compared to actual, measured flows to determine the degree to which streams have been altered.

This study was conducted by the USGS National Water-Quality Assessment Program.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by United States Geological Survey.

Journal Reference:

Daren M Carlisle, David M Wolock, Michael R Meador. Alteration of streamflow magnitudes and potential ecological consequences: a multiregional assessment. Frontiers in Ecology and the Environment, 2010; : 101025105601059 DOI: 10.1890/100053

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Helping fish get rid of the 'Ich'

ScienceDaily (Nov. 1, 2010) — Copper sulfate has emerged as an effective treatment for Ichthyophthirius multifiliis, also known as "Ich," a protozoan parasite that appears as white spots on infected fish, according to a U.S. Department of Agriculture (USDA) scientist.

Aquatic toxicologist David Straus with USDA's Agricultural Research Service (ARS) investigated copper sulfate as a method to control both Ich in catfish and a fungus -- Saprolegnia -- on catfish eggs. Straus works at the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center in Stuttgart, Ark. ARS is the chief intramural scientific research agency of USDA, and this research supports the USDA priority of promoting international food security.

Ich is considered the most prevalent parasite worldwide in ornamental fish, baitfish and food fish, according to Straus. Ich is less common in U.S. aquaculture because of management techniques, but when it occurs, it can kill all the fish in a pond or raceway. It is calculated that Ich was directly responsible for $1.2 million in losses to the catfish industry in 2003.

The freshwater fungus Saprolegnia is another major pathogen in fish culture, killing eggs and invading wounds and lesions on juvenile and adult fish.

Straus found copper sulfate is an effective treatment for Ich on fish and fungus on eggs. According to Straus, copper sulfate is the only practical treatment to control Ich in catfish ponds that average about 10 acres in area. It is easy to use, effective and inexpensive, and is safe for the user to handle.

Current approved treatments for fungus on eggs, such as formalin and hydrogen peroxide, are much more expensive. Also, both compounds are hazardous, and there are human safety concerns as well as required storage precautions.

Copper sulfate is not currently approved by the U.S. Food and Drug Administration for therapeutic use in aquaculture, but regulatory action has been deferred pending the outcome of Straus' ongoing research. The chemical is approved by the U.S. Environmental Protection Agency as an algicide and molluscicide. Fish farmers use copper sulfate to control cyanobacteria that cause off-flavor in fish, and to control snails that transmit parasitic flatworms to fish.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service.

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New fish feeds made from fish byproducts

ScienceDaily (Nov. 5, 2010) — Fish byproducts may be a new source of fish feed, thanks to research by U.S. Department of Agriculture (USDA)-funded scientists in Hawaii.

Research scientist Dong-Fang Deng and her colleagues with the Oceanic Institute in Waimanalo, Hawaii, are collaborating with USDA food technologist Peter Bechtel to develop the new fish feeds. Bechtel is with the USDA Agricultural Research Service (ARS) Subarctic Agricultural Research Unit in Kodiak, Alaska. ARS is the USDA's principal intramural scientific research agency.

The scientists are taking fish parts that would normally be discarded-head, tail, bone, skin and internal organs-and fashioning them into feeds for shrimp and fish. They are currently testing the feeds on Pacific threadfin (Polydactylus sexfilis)-or "moi" as Hawaiians call it-and Pacific white shrimp (Litopenaeus vannamei).

The researchers then characterize the nutrient composition of the feeds, evaluate their ability to attract the shrimp and moi, estimate the food's digestibility and assess the growth of the animals. Recent tests have shown that many of the Alaska fish parts work well as feeding stimulants, which entice the shrimp to eat the plant-protein-based feed to which fish byproducts had been added.

In an earlier ARS-funded study with moi, former Oceanic Institute scientist Ian Forster found that the nutritional quality of feeds made with discarded portions of Alaskan pollock and cod was equivalent to that of feed made from Norwegian fishmeal, generally regarded as the highest standard in the aquaculture feed industry. Forster and his colleagues found the same result when feeds were tested on shrimp.

According to Deng, the scientists are currently examining how to best use fish byproducts to develop practical feeds that are nutritionally balanced, cost effective and safe for the environment.

Details about these feed studies have been published in the Journal of the World Aquaculture Society and the Journal of Aquatic Food Product Technology.

Read more about this and other ARS aquaculture research in the October 2010 issue of Agricultural Research magazine: http://www.ars.usda.gov/is/AR/archive/oct10/leftovers1010.htm

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service. The original article was written by Stephanie Yao.

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Mysterious link between ancient lizard fossil in Africa and today's Komodo dragon in Indonesia

ScienceDaily (Nov. 17, 2010) — University of Alberta researchers have unearthed a mysterious link between bones of an ancient lizard found in Africa and the biggest, baddest modern-day lizard of them all, the Komodo dragon, half a world away in Indonesia.

Biologists Alison Murray and Rob Holmes say the unique shape of the vertebrae links the 33-million-year-old African lizard fossil with its cousin the Komodo, which has only been around for some 700,000 years.

"The African fossil was found on the surface of a windswept desert," said Holmes. "It's definitely from the lizard genus Varanus and there are more than 50 species alive today, including Komodos and other large lizards."

Holmes says the telltale African vertebrae fossils belonged to a lizard that was about a metre- and-a-half long whose ability to swim may be key to figuring out how more than 30 million years later its ancestors turned up on the other side of the world.

Holmes says the ancient African Varanus specimen was found on land that was once the bottom of a river or small lake. "Whether the animals lived in the water or surrounding land, we don't know, but we do know that some modern day species of Varanus are comfortable swimming in fresh water."

The researchers agree that fresh-water swimming wouldn't get the African lizard all the way to Indonesia. Murray says the mystery of how the animals spread deepens when you consider ancient world geography. "From about 100 million years ago until 12 million years ago, Africa was completely isolated, surrounded by ocean, but somehow they got out of Africa during that period," said Murray. "That's why this paper is important because there was no known land connection."

Murray says one unproven theory of how Varanus moved out of Africa is that over millions of years, small land masses or micro-plates may have moved from one place to another, carrying their fauna with them.

The work of the U of A researchers and various co-authors runs counter to some prevailing theories about the origins of some ancient fossil types found in Africa including Varanus lizards and some fresh-water fish. "The assumption for several types of ancient African fossils is that the animals didn't originate in Africa but came there from Asia," says Holmes. "But the fossil record of Varanus shows exactly the opposite path of migration."

The work of Murray and Holmes and various co-authors was published in the journal Palaeontology.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Alberta, via EurekAlert!, a service of AAAS.

Journal Reference:

Robert B. Holmes, Alison M. Murray, Yousry S. Attia, Elwyn L. Simons, Prithijit Chatrath. Oldest known Varanus (Squamata: Varanidae) from the Upper Eocene and Lower Oligocene of Egypt: support for an African origin of the genus. Palaeontology, 2010; 53 (5): 1099 DOI: 10.1111/j.1475-4983.2010.00994.x

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