A new as-of-yet unnamed species of humpback dolphin is shown off the coast of northern Australia. (Credit: Guido Parra)
Oct. 29, 2013 — A species of humpback dolphin previously unknown to science is swimming in the waters off northern Australia, according to a team of researchers working for the Wildlife Conservation Society, the American Museum of Natural History, and numerous other groups that contributed to the study.
To determine the number of distinct species in the family of humpback dolphins (animals named for a peculiar hump just below the dorsal fin), the research team examined the evolutionary history of this family of marine mammals using both physical features and genetic data. While the Atlantic humpback dolphin is a recognized species, this work provides the best evidence to date to split the Indo-Pacific humpback dolphin into three species, one of which is completely new to science.
“Based on the findings of our combined morphological and genetic analyses, we can suggest that the humpback dolphin genus includes at least four member species,” said Dr. Martin Mendez, Assistant Director of WCS’s Latin America and the Caribbean Program and lead author of the study. “This discovery helps our understanding of the evolutionary history of this group and informs conservation policies to help safeguard each of the species.”
The authors propose recognition of at least four species in the humpback dolphin family: the Atlantic humpback dolphin (Sousa teuszii), which occurs in the eastern Atlantic off West Africa; the Indo-Pacific humpback dolphin (Sousa plumbea), which ranges from the central to the western Indian Ocean; another species of Indo-Pacific humpback dolphin (Sousa chinensis), which inhabits the eastern Indian and western Pacific Oceans; and a fourthSousa species found off northern Australia yet to be named (the formal adjustment of the naming and number of species occurs through a separate and complementary process based on these findings).
“New information about distinct species across the entire range of humpback dolphins will increase the number of recognized species, and provides the needed scientific evidence for management decisions aimed at protecting their unique genetic diversity and associated important habitats,” said Dr. Howard Rosenbaum, Director of WCS’s Ocean Giants Program and senior author on the paper.
Working to bring taxonomic clarity to a widespread yet poorly known group of dolphins, the authors assembled a large collection of physical data gathered mostly from beached dolphins and museum specimens. Specifically, the team examined features from 180 skulls covering most of the distribution area of the group in order to compare morphological characters across this region.
The researchers also collected 235 tissue samples from animals in the same areas, stretching from the eastern Atlantic to the western Pacific Oceans, analyzing both mitochondrial and nuclear DNA for significant variations between populations.
The humpback dolphin grows up to 8 feet in length and ranges from dark gray to pink and/or white in color. The species generally inhabits coastal waters, deltas, estuaries, and occurs throughout the Indian and Pacific oceans to the coasts of Australia. The Atlantic humpback dolphin is considered “Vulnerable” according to the IUCN Red List, whereas the Indo-Pacific dolphin species Sousa chinensis is listed as “Near Threatened.” Humpback dolphins are threatened by habitat loss and fishing activity.
Originally published http://www.sciencedaily.com/releases/2013/10/131029143000.htm.
Posted October 29th, 2013. Add a comment
BY ROB JORDAN
Dan Griffin, Stanford aeronautics graduate student Ved Chirayath photographs coral reefs from below the water using a 360-degree camera.
Like undiscovered groves of giant redwoods, centuries-old living corals remain unmapped and unmeasured. Scientists still know relatively little about the world’s biggest corals, where they are and how long they have lived.
The secret to unlocking these mysteries may lie with a shoebox-size flying robot.
The robot in question is a four-rotor remote-controlled drone developed by Stanford aeronautics graduate student Ved Chirayath. The drone is outfitted with cameras that can film coral reefs from up to 200 feet in the air. Chirayath teamed up with Stanford Woods Institute Senior Fellow Stephen Palumbi to pioneer the use of drone technology to precisely map, measure and study shallow-water reefs off Ofu Island in American Samoa.
“Until now the challenges have been too high for flying platforms like planes, balloons and kites,” Palumbi said. “Now send in the drones.”
Chirayath, who also works as a scientist at NASA’s Ames Research Center, analyzes the drone’s footage using software he designed. The software removes distortions caused by surface wave movements and enhances resolution. To link the drone aerial footage to close-up images of corals, Chirayath and his colleagues are photographing reefs from below the water using a 360-degree camera. The result is a centimeter-scale optical aerial map and stunning gigapixel panoramic photographs of coral heads that stitch together thousands of images into one.
Surveys and maps of rainforests have resulted in new understanding of the vital role these ecosystems play in sustaining the biosphere. Detailed coral maps could do the same, allowing scientists to conduct precise species population surveys over large areas and assess the impact of climate change.
Rob Jordan is the communications writer for the Stanford Woods Institute for the Environment.
For more, please visit http://news.stanford.edu/news/2013/october/coral-reefs-drones-101613.html.
Posted October 21st, 2013. Add a comment
Spiked structures on male zebrafish pectoral fins are important for mating but also produce a potent signaling inhibitor. Presence of this inhibitor disrupts regeneration of fin tissue after amputation injury. (Credit: Developmental Cell, Kang et al.)
New research on the reproductive habits of zebrafish offers an explanation as to why some animals’ bodies repair tissues. The research team previously noticed that male zebrafish regenerate their pectoral fins poorly, as compared to females. Their latest findings, publishing in the October 14 issue of the Cell Press journalDevelopmental Cell, reveal the basis for this sex-specific regenerative deficiency: structures that are used to improve reproductive success. The scenario represents an example of the tradeoffs between reproduction and survival.
Led by first author Junsu Kang, the scientists identified anatomical structures that male fish use during mating that produce a signal that impedes regeneration of the pectoral fins after injury. As such, fish appear to trade an ancient ability to regenerate tissue easily for a new-found way of enhancing reproductive success. This valuable information could help scientists begin to explain why humans are less able to regenerate tissue and could also be used to improve the body’s tissue regenerative capacity.
“We discovered that male zebrafish have a very important set of structures on their pectoral fins that they use for breeding and that these structures secrete a potent molecular inhibitor of a key signaling pathway to aid their cycles of regular replacement,” explains senior author Kenneth Poss of Duke University Medical Center.
Higher vertebrates like mammals generally have a diminished capacity for tissue regeneration compared with lower vertebrates like fish and salamanders. “The biology we describe here suggests a new paradigm for how tissue regenerative capacity may be lost during species evolution,” says Poss. The researchers speculate that natural selection acting on traits like sexual features could have detrimental effects on tissue regenerative potential. For example, male zebrafish with more numerous or more effective breeding ornaments — and thus lower regenerative potential — might contribute more to the gene pool, phasing out regenerative potential over generations.
Poss notes that growing attention in the field of tissue regeneration is being paid to factors that block signaling pathways. “Our results indicate that the presence or restriction of a pathway inhibitor is critical to whether regeneration occurs normally, providing new fuel for ideas of how to promote regeneration after injury in humans.”
Originally published http://www.sciencedaily.com/releases/2013/10/131014121741.htm.
Posted October 16th, 2013. Add a comment
These arapaima, which were photographed in a public aquarium in the Ukraine, appear to be the new species recently described by Dr. Donald Stewart of SUNY-ESF. They clearly show the elongated sensory cavity as a dark bar on the lower side of the head, a feature that is known only for A. leptosoma. (Credit: Image courtesy of SUNY College of Environmental Science and Forestry)
A new species of the giant fish arapaima has been discovered from the central Amazon in Brazil, raising questions about what other species remain to be discovered and highlighting the potential for ecological problems when animals are relocated from their native habitats.
“Everybody for 160 years had been saying there’s only one kind of arapaima. But we know now there are various species, including some not previously recognized. Each of these unstudied giant fishes needs conservation assessment,” said Dr. Donald Stewart of the SUNY College of Environmental Science and Forestry (ESF), who made the discovery.
The discovery was reported in a paper Stewart recently published in the journal Copeia.
For two centuries, arapaima have been among the most important commercial fishes in freshwaters of the Amazon. “Arapaima have high economic, cultural and scientific value, but their diversity has been overlooked for too long,” Stewart said.
Four species of arapaima were recognized in the mid-1800s, but in 1868, Albert Günther, a scientist at the British Museum of Natural History, published an opinion that those were all one species, Arapaima gigas. Over time, Günther’s view became the prevailing wisdom.
“Until this year, no taxonomist has questioned Günther’s opinion about these iconic fishes,” Stewart wrote.
That lack of inquiry changed, however, when Stewart began studying the genus in Guyana and Brazil. “If you’re going to do conservation biology, you have to be sure about the taxonomy of the animals being studied,” he said. “If each study area has a different species, then results from one area should not be applied to manage populations in the next area.”
Delving into scientific literature from the 19th century and examining original specimens preserved at the National Museum of Natural History in Paris, Stewart concluded that all four of those originally described species were, in fact, distinct. Stewart re-described one of those original species (in a paper published in the March issue of Copeia) and summarized status of the other three species. Stewart’s most recent discovery came when he examined preserved arapaima at the Instituto Nacional de Pesquisas da Amazônia in Manaus, Brazil. This new description brings the total number of species to five.
The recently identified specimen was collected in 2001 near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is distinguished from all other arapaima by several characteristics, including the shape of sensory cavities on the head, a sheath that covers part of the dorsal fin and a distinctive color pattern. Its scientific name, A. leptosoma, is in reference to its slender body.
“Failure to recognize that there are multiple species has consequences that are far reaching,” Stewart said. “For example, there is a growing aquaculture industry for arapaima, so they are being moved about and stocked in ponds for rearing. Eventually pond-reared fishes escape and, once freed, the ecological effects are irreversible. A species that is endangered in its native habitat may become an invasive species in another habitat. The bottom line is that we shouldn’t be moving these large, predatory fishes around until the species and their natural distributions are better known. Given the uncertainties, precaution is needed.”
There is also the problem that arapaima are the most historically overexploited fishes of the Amazon Basin, having been subjected to intense and largely uncontrolled fishing pressure for at least a century. “Abundances of arapaima in large expanses of their natural habitat today are near-zero, largely as a consequence of overfishing,” said Dr. Leandro Castello, an authority on arapaima in Brazil. “The likely impacts of this magnitude of overfishing on species diversity are not good.”
Stewart said the newly discovered species is on display in a public aquarium in the Ukraine, where it was identified as Arapaima gigas, the single name that has been applied to all arapaima for the past 140 years. It thus appears this new species already is being cultured and exported from South America, but under the wrong name.
Stewart’s work was supported by ESF and the National Geographic Society.
Originally published http://www.sciencedaily.com/releases/2013/10/131014102323.htm.
Posted October 15th, 2013. Add a comment
Photograph by Bos11/Shutterstock.
DETROIT – A skin infection linked to exposure to contaminated water in home aquariums is frequently under-diagnosed, according to a Henry Ford Hospital study.
Researchers say diagnosing and managing Mycobacterium marinum infection is difficult because skin lesions don’t appear for two to four weeks after incubation, leading to delayed treatment and unnecessary and ineffective use of antifungal and antibacterial agents.
During the incubation period, patients also fail to remember the source of the exposure, which is often traced to them cleaning their aquarium. Infection results when bacteria in the non-chlorinated water attacks an open skin wound on the arm or hand.
“People just don’t know or think about their fish tank harboring this bacterial organism,” says George Alangaden, M.D., a Henry Ford Infectious Diseases physician and the study’s lead author.
“And unless they’re directly questioned about it by their physician, who may or may not have adequate knowledge of Mycobacterium marinum and its prolonged incubation period, appropriate treatment often gets delayed.”
The study is being presented Saturday at the Infectious Diseases Society of America’s annual meeting in San Francisco.
In a retrospective study conducted between January 2003 and March 2013, researchers identified five patients ages 43 to 72 treated at Henry Ford for Mycobacterium marinum, which resemble reddish skin lesions or bumps on the hands or arms. Skin biopsies performed on all five patients confirmed the infection.
The incubation period before skin lesions appeared ranged from 11 to 56 days. While all five patients responded effectively to antibiotic treatment, it took on average 161 days from the time of initial presentation to time of treatment.
“Mycobacterium marinum is not a life-threatening illness, but it remains an unrecognized cause of skin infection,” says Dr. Alangaden. “To accelerate diagnosis and treatment, physicians are encouraged to ask detailed questions about the patient’s history, especially questions about potential exposure to aquariums.”
The study was funded by Henry Ford Hospital
Originally published http://www.henryford.com/body.cfm?id=46335&action=detail&ref=1972
Posted October 11th, 2013. Add a comment
For years, researchers have tried to explain how coral reef communities—some of the most productive ecosystems in the world—can thrive in waters that don’t have any nutrients. Somehow, these diverse ecosystems can grow very well in the marine equivalents of a desert—a mystery that has become known as “Darwin’s Paradox.”
Previous research has shown that tiny microbes can take some of the organic matter that’s dissolved into the ocean by coral and algae and convert it to food for larger organisms. But, those microbes have never been enough to explain how coral reefs are able to recycle all of the organic matter that’s produced by the reefs without losing most of it to the ocean.
Now, Jasper de Goeij and colleagues say that sponges have been the missing piece of the puzzle this whole time. The researchers studied four species of coral reef sponges and found that each one of them absorbed carbon and nitrogen from their surroundings and converted it to nutrient-rich filter cells. These filter cells are then quickly released into the water to be eaten by other creatures, like snails and hermit crabs, they say.
This “sponge loop” helps to explain how biological hot spots, such as coral reefs, do so well in parts of the ocean that lack nutrients like carbon and nitrogen. Sponges have been saving nutrients from drifting out to sea and turning them into food for larger organisms to consume, according to the researchers.
Originally published http://www.eurekalert.org/features/kids/2013-10/aaft-srr092713.php
Posted October 10th, 2013. Add a comment
Sep. 25, 2013 — A previously unknown genus of electric fish has been identified in a remote region of South America by team of international researchers including University of Toronto Scarborough professor Nathan Lovejoy.
The Akawaio penak. (Credit: Nathan Lujan)
The Akawaio penak, a thin, eel-like electric fish, was discovered in the shallow, murky waters of the upper Mazaruni River is northern Guyana.
Lovejoy’s team at UTSC analyzed tissue samples collected during a recent expedition by researchers led by Hernán López-Fernández at the Royal Ontario Museum. By sequencing its DNA and reconstructing an evolutionary tree, Lovejoy’s team discovered the fish is so distinct it represents a new genus, the taxonomic classification level above species.
The upper Mazaruni River is a hotspot for biological diversity, yet remains largely unexplored because of its remote location. The area contains countless rivers on top of a series of uplands that have remained isolated from the rest of South America for more than 30 million years.
“The fact this area is so remote and has been isolated for such a long time means you are quite likely to find new species,” says Lovejoy.
Like other electric knifefish, Akawaio penak has a long organ running along the base of the body that produces an electric field. The electric field is too weak to stun prey but is instead used to navigate, detect objects and to communicate with other electric fish. This trait is advantageous given the murky habitats of the fish.
The species is named in honour of the Akawaio Amerindians that populate the upper Mazaruni. The region is increasingly suffering from freshwater habitat degradation as a consequence of gold-mining in the area.
“The Mazaruni contains many unique species that aren’t found anywhere else in the world. It’s an extremely important area in South America in terms of biodiversity,” says Lovejoy.
The results of the discovery are published in the recent edition of the journal Zoologica Scripta.
Originally published http://www.sciencedaily.com/releases/2013/09/130925092233.htm
Posted September 27th, 2013. 1 comment
Plankton Portal uses crowd-sourcing to classify strange oceanic creatures
SEPTEMBER 17, 2013 (MIAMI, FL USA)—Today, an online citizen-science project launches called “Plankton Portal” was created by researchers at the University of Miami Rosenstiel School of Marine and Atmospheric Sciences (RSMAS) in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF) and developers at Zooniverse.org Plankton Portal allows you to explore the open ocean from the comfort of your own home. You can dive hundreds of feet deep, and observe the unperturbed ocean and the myriad animals that inhabit the earth’s last frontier.
The goal of the site is to enlist volunteers to classify millions of underwater images to study plankton diversity, distribution and behavior in the open ocean. It was developed under the leadership of Dr. Robert K. Cowen, UM RSMAS Emeritus Professor in Marine Biology and Fisheries (MBF) and now the Director of Oregon State University’s Hatfield Marine Science Center, and by Research Associate Cedric Guigand and MBF graduate students Jessica Luo and Adam Greer.
Millions of plankton images are taken by the In Situ Ichthyoplankton Imaging System (ISIIS), a unique underwater robot engineered at the University of Miami in collaboration with Charles Cousin at Bellamare LLC and funded by NOAA and NSF. ISIIS operates as an ocean scanner that casts the shadow of tiny and transparent oceanic creatures onto a very high resolution digital sensor at very high frequency. So far, ISIIS has been used in several oceans around the world to detect the presence of larval fish, small crustaceans and jellyfish in ways never before possible. This new technology can help answer important questions ranging from how do plankton disperse, interact and survive in the marine environment, to predicting the physical and biological factors could influence the plankton community.
“ISIIS gives us a new view on plankton, enabling us to see them in their natural setting, where they occur, what other organisms are nearby, even their orientation,” explains Cowen.
The dataset used for Plankton Portal comes from a project from the Southern California Bight, where Cowen’s team imaged plankton across a front, which is a meeting of two water masses, over three days in Fall 2010.
According to Jessica Luo, graduate student involved in this project, “in three days, we collected data that would take us more than three years to analyze.” Cowen agrees: “with the volume of data that ISIIS generates, it is impossible for us to individually classify every image by hand, which is why we are exploring different options for image analysis, from automatic image recognition software to crowd-sourcing to citizen scientists.”
“A computer will probably be able to tell the difference between major classes of organisms, such as a shrimp versus a jellyfish,” explains Luo, “but to distinguish different species within an order or family, that is still best done by the human eye.” Volunteer citizen scientists can assist by going to http://www.planktonportal.org. A field guide is provided, and the simple tutorial is easy to understand. Cowen and the science team will monitor the discussion boards; answer any questions about the classifications, the organisms, and the research they are conducting.
Photograph by Oregon State University
Posted September 17th, 2013. Add a comment
MANILA, PHILIPPINES – Larvae-eating guppy fish can help combat the spread of dengue, a mosquito-borne illness giving rise to hundreds of thousands of severe cases including 20,000 deaths worldwide every year, according to a trial study by the Governments of Cambodia and the Lao People’s Democratic Republic (Lao PDR) with the support of the Asian Development Bank (ADB) and the World Health Organization (WHO).
“This is a low-cost, year-round, safe way of reducing the spread of dengue in which the whole community can participate,” said ADB health specialist Gerard Servais. “It offers a viable alternative to using chemicals and can reduce the scale of costly emergency response activities to contain epidemics.”
The community-based project, conducted in two districts in Cambodia and the Lao PDR from 2009 to 2011, resulted in a sharp decline in mosquito larvae in water storage tanks after the tiny fish were introduced. Guppies eat larvae that grow into mosquitoes, which in turn bite humans and transmit dengue.
Dengue causes severe joint and muscle pain, headache, high fever and rashes and is fatal in a small proportion of cases, in particular if not diagnosed and treated early. Outbreaks of the illness not only affect families with sudden health care costs and loss of incomes for adults put out of work, but also impact health services, businesses and tourism, straining government budgets due to unplanned spending on large-scale emergency response measures. Currently there is still no vaccine or specific medicine to treat this viral disease.
Around 2.5 billion people worldwide are at risk of contracting dengue, more than 70% of whom live in Asia and the Pacific. The threat of exposure to dengue-carrying mosquitoes is rising with uncontrolled urbanization and a surge in the use of non-biodegradable packaging, which can act as a water reservoir for dengue mosquito breeding. Dengue is spread by a specific mosquito that breeds readily in standing water, such as found in storage containers, flower pots and discarded tires. The guppies are particularly effective in these settings.
Convincing communities to accept fish in their water containers was a key element of the project. The trial showed that guppies do not harm water quality and can survive on microscopic organic material in the absence of mosquito larvae. At the project close in Cambodia, about 88% of the storage containers contained guppies, with the figure at 76% in Lao PDR.
“The project was successful in mobilizing communities with widespread grassroots participation, and high levels of acceptance of fish as an effective way of reducing the spread of dengue,” said Dr. Eva Christophel, a WHO specialist in vectorborne diseases. “This project was an important contribution to WHO’s efforts to develop a toolkit of different community-based methods to prevent and reduce the magnitude of dengue transmission.”
ADB provided financing of $1 million for the project.
- See more at: ResearchSea
Posted September 13th, 2013. 1 comment
Photo by Thomas P. Quinn.
SEATTLE – Sept. 12, 2013 – How and why fish swim in schools has long fascinated biologists looking for clues to understand the complexities of social behavior. A new study by a team of researchers at Fred Hutchinson Cancer Research Center may help provide some insight.
To be published online in the Sept. 12 issue of Current Biology, the study found that two key components of schooling – the tendency to school and how well fish do it – map to different genomic regions in the threespine stickleback, a small fish native to the Northern Hemisphere.
That’s important, said lead author Anna Greenwood, Ph.D., because it suggests that if researchers can identify the genes that influence the fishes’ interest in being social, they may be closer to understanding how genes drive human social behavior.
“The motivation to be social is common among fish and humans,” said Greenwood, a staff scientist in the Human Biology Division at Fred Hutch. “Some of the same brain regions and neurological chemicals that control human social behavior are probably involved in fish social behavior as well.”
‘Some kind of genetic factor’ controlling behavior
Greenwood and several colleagues in the Peichel Labat Fred Hutch have been studying sticklebacks for several years to understand the genesis of natural variation. In a previous study, they found that a group of marine sticklebacks from the Pacific Ocean in Japan schooled strongly, while a second group from a lake in British Columbia preferred hiding out and were less able to maintain the precisely parallel formation required for schooling.
Though both groups were raised in identical lab conditions, they behaved differently from each other when placed together in a schooling situation.
“That really suggests that there’s some kind of genetic factor controlling this difference,” Greenwood said.
This time around, the researchers used lab-raised hybrids of the strongly schooling, saltwater-dwelling marine sticklebacks and the schooling-averse sticklebacks that live in freshwater.
Alison Bell, Ph.D., an associate professor of animal biology at the University of Illinois, Urbana-Champaign, said the linking of behaviors to different genomic regions in the same species – and in particular, social behavior that depends on the behavior of others – makes the study especially compelling.
“I think that’s very significant,” she said. “It’s been hard to find regions of the genome that are associated with any kind of behavioral traits in natural populations. Behavior is very plastic and it’s subject to environmental influences, so it’s been really tricky to do that.”
Hans Hofmann, Ph.D., a professor of integrative biology at the University of Texas at Austin, said the study also refutes the assertion that human behavior is too complex to understand.
“I think it shows that even such complex behaviors associated with other individuals in a very rigid and organized manner can be dissected genetically,” he said. “Studies like this tell us that we might get there eventually.”
Old bicycle wheel and lab motor used in experiment
Fish school primarily for protection from predators, and also to make swimming and foraging more efficient. Schools of fish in the wild are dynamic and fluid, but for both studies the Fred Hutch researchers had to create an environment in which they could observe the fish in unchanging conditions.
Building the device used for both experiments proved a challenge. The researchers suspended an old bicycle wheel above a circular acrylic tank and found a motor from an old lab shaker that could turn the wheel, but were stumped about how to connect them.
Greenwood and co-author Abigail Wark scoured craft shops and hardware stores looking for a suitable part, trying everything from plastic bra straps to necklaces before finding some silicone tubing that worked.
“It was a few weeks of going around to shops,” Greenwood said.
They made a mold to create model fish from resin tinted with grey pigment, dabbing on eyes with black paint to make them look more realistic. The eight models (they found that eight is the minimum number to get fish to school in a lab setting) were suspended from the bike wheel with wire.
Beyond its findings connecting specific behaviors with genomic regions, the study also found that the same regions of the genome appear to control both the stickleback’s ability to school as well as the anatomy of its lateral line, a system of organs that detect movement and vibration in water, and contain the same sensory hair cells found in the human ear.
That suggests a single gene could cause fish to detect their environment differently, Greenwood said, and supports the long-held notion that schooling behavior is controlled in part by the lateral line.
It provides a promising starting point in trying to locate the gene involved, and Fred Hutch researchers are now working on manipulating the gene they think causes changes in the stickleback’s lateral line to see if that alters the fishes’ schooling behavior.
Research on schooling behavior in fish may seem an odd fit for a cancer research center, but Greenwood said natural variation can influence not just behavior, but also susceptibility to illness and disease.
“If we can understand the process by which evolution works and the genes that tend to be affected during evolution in these other model systems, we can apply that to humans,” she said.
Source: Fred Hutchinson Cancer Research Center
Posted September 12th, 2013. Add a comment