Tag: Cetacean

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Whale microbiome shares characteristics with both ruminants, predators

To some, it may not come as a surprise to learn that the great whales are carnivores, feeding on tiny shrimp-like animals such as krill. Moreover, it might not be surprising to find that the microbes that live in whale guts -the so-called microbiome- resemble those of other meat eaters. But scientists now have evidence that the whales’ microbiome shares traits with creatures not known to eat meat — cows.

Led by Peter Girguis, Professor of Organismic and Evolutionary Biology, scientists have found that the gut microbiome of right whales and other baleen species shares characteristics with both cows and meat-eating predators. The dual microbial communities allow whales to extract the most nutrition possible from their diet, digesting not only the copepods they eat, but their chitin-rich shells as well. The study is described in a September 22 paper in Nature Communications.

“From one point of view, whales look like carnivores,” Girguis said. “They have the same kind of microbes that we find in lions and tigers that have very meat-rich diets. But they also have abundant communities of anaerobic bacteria, similar to those that ruminants use to break down cellulose.

“However, there’s not a lot of cellulose in the ocean, but there is a lot of chitin, which is in the exoskeletons of copepods that baleen whales eat,” Girguis continued. “What our paper suggests is the whale foregut is much like a cow’s gut, and we posit that chitin-degrading anaerobic microbial community thrives in there, breaking down that material and making it available to the whale.”

Those exoskeletons, Girguis said, represent as much as ten percent of whale’s total food intake, and would otherwise simply be defecated. By allowing whales to access the nutrition in the chitin-rich material, whales are able to extract the most possible benefit from their diet.

“It’s almost like a pre-adaptation,” he said “that may give them a differential advantage in harnessing energy from their food. The morphology of their gut comes from their ancestors, the very same ancestors to cows, camels and other ruminants. It serves them well even as carnivores because it allows them to maximally extract nutrition from their food.”

Ultimately, Girguis said, the study addresses questions that reach far beyond the guts of whales. “This is really a question of what we can call phylogenetic inertia,” he said. “Because what we’re really thinking about is: When you look at the microbiome of an organism, you can -to some degree- look back in time and see its ancestors, because organisms that are related to one another seem to have similar microbiomes.

“But not all organisms that are related live in the same kind of environment,” he continued. “So the question is how different does your environment need to be before it changes your microbiome? This is a fundamental question about the relationship between your ancestry versus your current environment.” Many of those questions, however, might not have been asked, Girguis said, were it not for then-undergraduate student Annabel Beichman.

Now a graduate student at UCLA and the second author of the study, Beichman kick-started the study when she and University of Vermont conservation biologist Joe Roman took on the unenviable task of following pods of right whales at sea and collecting samples of their feces to determine which microbes were present. “There’s no other way to get the fecal samples but to collect them from the ocean,” Roman said.

“It was a thrill to set out each morning into uncertain weather to search for elusive right whales, then to extract and sequence DNA from our smelly trophies,” Beichman said. “It had always been my passion to use the latest advances in genetic sequencing technology to answer questions about species of conservation concern, and so I wanted to add a genetic component to the study.

“Working with my advisors to conceive the research questions based on the scientific literature, collect fecal samples in the field, and carry out DNA sequencing and analysis gave me invaluable experience at every stage of the study,” she added. “We all had different theories as to what the whale gut community might look like. What none of us expected was to see so much divergence from terrestrial mammals, or these shared characteristics with both terrestrial carnivores’ and herbivores’ microbiomes.”

“Given what we know about whales’ ancestry — that they’re related to ruminants, and that they still have a multi-chambered foregut — there were several things we might find,” Girguis said. “One hypothesis was that their microbiome would look like those of other meat-eaters like lions and tigers, and the foregut was just vestigial. The other hypothesis was that it allowed a different group of microbes to do something we hadn’t thought about. What we found was that whales have a microbiome that looks halfway like a ruminant and halfway like a carnivore.

“We’ve come to better understand the evolution of whales over the past few decades, and see where they fit on the evolutionary tree. But we have not understood the microbial changes that have allowed them to become one of the most successful groups of animals in the ocean,” said Roman. “This study helps explain that.”

Going forward, Girguis and colleagues hope to sample the microbial community in whales’ stomach chambers, and to extend the study to toothed whales, which don’t have such chitin-rich diets. The team has also received interest from aquariums, which may be able to use information about the gut microbes in whales in order to better care for animals kept in captivity.

“A lot of aquariums…they know when their whales are healthy or not, but they don’t always have a causal factor, and these gut microbes may be a big clue,” Girguis said. “As long as people keep whales in captivity, there is value in this type of research, because it can keep them as healthy as possible.”

While it may not provide a definitive answer to questions of phylogenetic inertia, the study does suggest that some morphological features, if they can provide an advantage, are retained, despite dramatic changes in a creature’s environment.

“We now have this snapshot that addresses this question of how a creature’s evolutionary past interacts with its microbiome, and how their diet today influences their microbiome,” he said. “The answer is…if that morphological feature, if it has value to a species, then it may well be something that’s capitalized on over evolutionary time.

http://www.sciencedaily.com   Science Daily

http://www.sciencedaily.com/releases/2015/09/150922163313.htm  Original web page at Science Daily

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Dolphins use extra energy to communicate in noisy waters

Scientists trained dolphins to whistle at different sound levels under a hood that measures oxygen consumption as an indicator of their metabolic rate. The dolphins are part of Dr. Terrie Williams’ Mammalian Physiology lab at the University of California Santa Cruz. All procedures were approved by the UC Santa Cruz Institutional Animal Care and Use Committee and conducted under U.S. National Marine Fisheries Service permit No.13602.

Dolphins that raise their voices to be heard in noisy environments expend extra energy in doing so, according to new research that for the first time measures the biological costs to marine mammals of trying to communicate over the sounds of ship traffic or other sources. While dolphins expend only slightly more energy on louder whistles or other vocalizations, the metabolic cost may add up over time when the animals must compensate for chronic background noise, according to the research by scientists at NOAA Fisheries’ Northwest Fisheries Science Center and the University of California Santa Cruz. “If they’re repeatedly exposed to a lot of noise, the repeated effort to call louder or longer or more often — that’s where the impacts could become more significant,” said Marla Holt, a research biologist at the Northwest Fisheries Science Center in Seattle and lead author of the paper published this week in the Journal of Experimental Biology.

The impacts could be pronounced for young, growing animals or nursing females already struggling to eat enough to maintain their energy balance, the researchers concluded. Some animals also react to nearby vessels and associated noise by slapping their tails on the water or breaching — jumping clear out of the water. That could add to the extra effort required by louder calls to further drain their energy. “You have to try to piece all these energetic costs together to analyze the increased metabolic expense that they incur when they’re around different sources of disturbance,” said Dawn Noren, a NWFSC research biologist who specializes in physiology of marine mammals and coauthor of the research.

The report also noted that ship noise can interfere with the echolocation the whales use to locate and hunt for food. The new findings suggest that consistently noisy surroundings could take a toll on marine mammals that rely on calls for basic life functions such as communication and foraging. “If they are going to have to compensate for long periods, day after day, then that cumulative impact could be a concern,” Noren said. “How much more fish will they need to eat to compensate for that? That is a concern for these whales because we know their food sources may be limited.” The research examined the energy expenditures of trained captive dolphins at UC Santa Cruz as stand-ins for killer whales, since the species produce sound in similar ways. The dolphins were trained to whistle softly as they might in quiet conditions and more loudly as they would in situations with greater background noise. Plastic hoods over the dolphins measured their oxygen consumption as a gauge of how much energy they expended in producing the whistles of different volumes.

The study found that the dolphins consumed about 80 percent more oxygen when whistling at the highest vocal energy levels than they did at rest. Dolphins have been found to whistle at higher repetition rates when boats are approaching, a behavior that is predicted to expended more energy based on the study’s results. The results are consistent with other similar studies on birds and humans that also found similar increases in oxygen consumption associated with longer, more frequent and louder calls. “These data would have been impossible to collect from wild animals, so without these trained dolphins we could not have conducted this study,” Noren said.

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2015/04/150423130436.htm

Original web page at Science Daily

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World’s whaling slaughter tallied

The first global estimate of the number of whales killed by industrial harvesting last century reveals that nearly 3 million cetaceans were wiped out in what may have been the largest cull of any animal — in terms of total biomass — in human history. The devastation wrought on whales by twentieth-century hunting is well documented. By some estimates, sperm whales have been driven down to one-third of their pre-whaling population, and blue whales have been depleted by up to 90%. Although some populations, such as minke whales, have largely recovered, others — including the North Atlantic right whale and the Antarctic blue whale — now hover on the brink of extinction. But researchers had hesitated to put a number on the global scale of the slaughter. That was largely because they did not trust some of the information in the databases of the International Whaling Commission, the body that compiles countries’ catches and that manages whaling and whale conservation, says Robert Rocha, director of science at the New Bedford Whaling Museum in Massachusetts.

Rocha, together with fellow researchers Phillip Clapham and Yulia Ivashchenko of the National Marine Fisheries Service in Seattle, Washington, has now done the maths, in a paper published last week in Marine Fisheries Review (R. C. Rocha Jr, P. J. Clapham and Y. V. Ivashchenko Mar. Fish. Rev. 76, 37–48; 2014). “When we started adding it all up, it was astonishing,” Rocha says. The researchers estimate that, between 1900 and 1999, 2.9 million whales were killed by the whaling industry: 276,442 in the North Atlantic, 563,696 in the North Pacific and 2,053,956 in the Southern Hemisphere.

Other famous examples of animal hunting may have killed greater numbers of creatures — such as hunting in North America that devastated bison and wiped out passenger pigeons. But in terms of sheer biomass, twentieth-century whaling beat them all, Rocha estimates. “The total number of whales we killed is a really important number. It does make a difference to what we do now: it tells us the number of whales the oceans might be able to support,” says Stephen Palumbi, a marine ecologist at Stanford University in California. He thinks that 2.9 million whale deaths is a “believable” figure.

http://www.nature.com/news/index.html  Nature

http://www.nature.com/news/world-s-whaling-slaughter-tallied-1.17080  Original web page at Nature

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Heart arrhythmias detected in deep-diving marine mammals

A new study of dolphins and seals shows that despite their remarkable adaptations to aquatic life, exercising while holding their breath remains a physiological challenge for marine mammals. The study, published January 15 in Nature Communications, found a surprisingly high frequency of heart arrhythmias in bottlenose dolphins and Weddell seals during the deepest dives. The normal dive response in marine mammals has long been understood to involve a marked reduction in heart rate (called bradycardia) and other physiological changes to conserve limited oxygen reserves while the air-breathing animals are underwater. How marine mammals cope with the exertion needed to pursue prey at depth has been unclear, however, since the normal physiological response to exercise is an increase in heart rate (called tachycardia). The new study shows that these conflicting signals to the heart can lead to cardiac arrhythmias, said lead author Terrie Williams, a professor of ecology and evolutionary biology at UC Santa Cruz.

“This study changes our understanding of bradycardia in marine mammals,” Williams said. “The heart is receiving conflicting signals when the animals exercise intensely at depth, which often happens when they are starting their ascent. We’re not seeing lethal arrhythmias, but it is putting the heart in an unsteady state that could make it vulnerable to problems.” Instead of a single level of reduced heart rate during dives, the researchers found that heart rates of diving animals varied with both depth and exercise intensity, sometimes alternating rapidly between periods of bradycardia and tachycardia. Cardiac arrhythmias occurred in more than 70 percent of deep dives. “We tend to think of marine mammals as completely adapted to life in the water. However, in terms of the dive response and heart rate, it’s not a perfect system,” Williams said. “Even 50 million years of evolution hasn’t been able to make that basic mammalian response impervious to problems.” The conflict between dive-induced bradycardia and exercise-induced tachycardia involves two different neural circuits that regulate heart rate, she said. The sympathetic nervous system stimulates the heart during exercise, whereas the parasympathetic nervous system controls the slowing of the heart rate during the dive response.

The new findings have implications for efforts to understand stranding events involving deep-diving marine mammals such as beaked whales. The authors note that the behaviors associated with cardiac anomalies in this study (increased physical exertion, deep diving, and rapid ascent from depth) are the same as those involved in the flight response of beaked whales and blue whales exposed to shipping noise and mid-frequency sonars. “This study is not saying that these deep-diving animals will die if they exercise hard at depth,” Williams said. “Rather, it raises questions about what happens physiologically when extreme divers are disturbed during a dive, and it needs further investigation.”

The study’s findings may also be relevant in humans, she said. The mammalian dive response or dive reflex, though most pronounced in marine mammals, also occurs in humans and other terrestrial animals and is triggered when the face contacts cold water. A 2010 study of triathlons found that the swimming segment of cold water triathlons accounts for over 90 percent of race day deaths. “It may be that the same conflicting signals we saw in dolphins and seals are causing arrhythmias in some triathletes,” Williams said. She is currently working with triathlon groups to help mitigate such problems during races. To conduct the study, the researchers developed a monitoring device to record heart rate, swimming stroke frequency, depth, and time throughout the dives of trained bottlenose dolphins diving in pools or open water, as well as free-ranging Weddell seals swimming beneath the ice in McMurdo Sound, Antarctica. Williams said the animals typically used low-intensity swimming modes as much as possible during dives. When hunting fish beneath the ice, Weddell seals alternated between easy glides and short chases in pursuit of prey. This behavior appeared to enable the marine mammals to avoid cardiac conflicts and associated arrhythmias during hunting.
http://www.sciencedaily.com/ Science Daily

http://www.sciencedaily.com/releases/2015/01/150116085554.htm Original web page at Science Daily

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Iberian orcas, increasingly trapped

Thanks to the more than 11,200 sightings of cetaceans over the course of ten years, Spanish and Portuguese researchers have been able to identify, in detail, the presence of orcas in the Gulf of Cadiz, the Strait of Gibraltar and the Alboran Sea. According to the models that have been generated, the occurrence of these cetaceans is linked to the distribution of their main prey (red tuna) and their presence in Spanish, Portuguese and Moroccan waters is thus more limited than previously thought. In 2011, the Spanish Ministry of the Environment considered the small population of orcas (Orcinus orca) that inhabits the waters in the south of Spain to be ‘vulnerable’, and included it in the Spanish Catalogue of Endangered Species. Its addition was justified: the orcas that live in this area belong to a reduced group of individuals that each year swims between the Strait of Gibraltar and the Gulf of Cadiz in search of tuna. Despite efforts to demarcate the spatial distribution of this group of cetaceans, until now little was known about their movements during spring and summer in the Alboran Sea, the Strait of Gibraltar and the Gulf of Cadiz. The new study, published in the ‘Journal of the Marine Biological Association of the United Kingdom’, allows their location each year to be identified with greater precision.

“We have created two generalised models: the presence model (sightings of orcas) and the pseudo-absence model (sightings of other cetaceans), with the information gathered from the 11,276 sightings between 2002 and 2012,” Ruth Esteban, the main author of the study and a researcher for Conservation, Information and Research on Cetaceans (CIRCE), said. The scientists created a model using data from spring, when red tuna (orcas’ main prey) enter into the Mediterranean Sea, and another model with data from summer, when red tuna leave for the Atlantic Ocean. The results show that the presence of orcas is closely linked to the distribution of the tuna during their migration through the studied area. “This limits their distribution to the Gulf of Cadiz in spring and the Strait of Gibraltar in summer,” notes Esteban. Furthermore, “any reduction in the abundance of tuna could endanger this population of orcas,” the researcher adds. She considers it important to demarcate an exclusive marine area where human activity, such as whale watching, military exercises or recreational fishing, does not interrupt their predation techniques. According to the predictions of the model generated using 278 orca sightings and 7,206 of other cetaceans, it has been forecast that in summer there will be a large number of orcas in the most westerly part of the centre of the Strait of Gibraltar. The 44 sightings of orcas from research vessels, whale watching companies and opportunist observations and the 3,746 sightings of other cetaceans have shown that the orcas remain in two specific areas in spring: in the most easterly area of the Gulf of Cadiz -in shallow waters around Spain and Morocco-, and in southern Portugal, in particular close to Faro. In the Alboran Sea, only four orca sightings have been registered in ten years. Scientists have therefore not been able to identify any important habitat area with the models used in the other areas. During autumn and winter, orcas have barely been observed in the most regularly populated areas. “It is possible that this group of marine mammals travels in waters close to the migration route of the tuna,” the researchers have concluded.

http://www.sciencedaily.com/ Science Daily

http://www.sciencedaily.com/releases/2014/11/141126111120.htm Original web page at Science Daily

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*Dolphin ‘breathalyzer’ could help diagnose animal and ocean health

Alcohol consumption isn’t the only thing a breath analysis can reveal. Scientists have been studying its possible use for diagnosing a wide range of conditions in humans — and now in the beloved bottlenose dolphin. In a report in the ACS journal Analytical Chemistry, one team describes a new instrument that can analyze the metabolites in breath from dolphins, which have been dying in alarming numbers along the Atlantic coast this year. Cristina E. Davis and colleagues note that studying dolphins’ health is about more than preserving their populations — the popular mammals also can serve as sentinels for overall ocean health. But invasive techniques such as skin biopsies and blood sampling, which are the most effective ways to test their health, are difficult to perform. An intriguing alternative comes from research on human-health monitoring with breath analyzers. Exhaled breath contains compounds called metabolites that can hint at a person’s diet, activity level, environmental exposures or disease state. Davis’ team wanted to develop a way to capture dolphin breath so they could gather this kind of information on marine mammals. The researchers designed an insulated tube customized to trap the breath exhaled from the blowhole of the bottlenose dolphin. They tested it on dolphins both in the wild and under human care. The scientists established baseline breath profiles of healthy animals and identified changes in the breath of animals affected by disease or other factors. The researchers conclude that breath analysis could someday be used to diagnose and monitor problems in marine mammals — and by extension, in ocean health.

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2014/10/141015112325.htm  Original web page at Science Daily

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Killer whales learn to communicate like dolphins

From barks to gobbles, the sounds that most animals use to communicate are innate, not learned. However, a few species, including humans, can imitate new sounds and use them in appropriate social contexts. This ability, known as vocal learning, is one of the underpinnings of language. Vocal learning has also been observed in bats, some birds, and cetaceans, a group that includes whales and dolphins. But while avian researchers have characterized vocal learning in songbirds down to specific neural pathways, studying the trait in large marine animals has presented more of a challenge. Now, University of San Diego graduate student Whitney Musser and Hubbs-SeaWorld Research Institute senior research scientist Dr. Ann Bowles have found that killer whales (Orcinus orca) can engage in cross-species vocal learning: when socialized with bottlenose dolphins, they shifted the types of sounds they made to more closely match their social partners. The results, published in The Journal of the Acoustical Society of America, suggest that vocal imitation may facilitate social interactions in cetaceans. Killer whales have complex vocal repertoires made up of clicks, whistles and pulsed calls — repeated brief bursts of sound punctuated with silence. The acoustic features of these vocalizations, such as their duration, pitch and pulse pattern, vary across social groups. Whales that are closely related or live together produce similar pulsed calls that carry vocal characteristics distinct to the group, known as a dialect. “There’s been an idea for a long time that killer whales learn their dialect, but it isn’t enough to say they all have different dialects so therefore they learn. There needs to be some experimental proof so you can say how well they learn and what context promotes learning,” said Bowles. Testing vocal learning ability in social mammals usually requires observing the animal in a novel social situation, one that might stimulate them to communicate in new ways. Bottlenose dolphins provide a useful comparison species in this respect: they make generally similar sounds but produce them in different proportions, relying more on clicks and whistles than the pulsed calls that dominate killer whale communication. “We had a perfect opportunity because historically, some killer whales have been held with bottlenose dolphins,” said Bowles. By comparing old recordings of vocalization patterns from the cross-socialized subjects with recordings of killer whales and bottlenose dolphins housed in same-species groups, Bowles and her team were able to evaluate the degree to which killer whales learned vocalization patterns from their cross-species social partners.

All three killer whales that had been housed with dolphins for several years shifted the proportions of different call types in their repertoire to more closely match the distribution found in dolphins — they produced more clicks and whistles and fewer pulsed calls. The researchers also found evidence that killer whales can learn completely new sounds: one killer whale that was living with dolphins at the time of the experiment learned to produce a chirp sequence that human caretakers had taught to her dolphin pool-mates before she was introduced to them. Vocal learning skills alone don’t necessarily mean that killer whales have language in the same way that humans do. However, they do indicate a high level of neural plasticity, the ability to change circuits in the brain to incorporate new information. “Killer whales seem to be really motivated to match the features of their social partners,” said Bowles, though the adaptive significance of the behavior is not yet known. There are immediate reasons to study the vocal patterns of cetaceans: these marine mammals are threatened by human activities through competition for fishery resources, entanglement in fishing gear, collisions with vessels, exposure to pollutants and oil spills and, ultimately, shrinking habitats due to anthropogenic climate change. If their social bonds are closely linked to their vocalizations, killer whales’ ability to survive amidst shifting territories and social groups may be tied to their ability to adapt their communication strategies. It’s important to understand how they acquire their vocalization patterns, and lifelong, to what degree they can change it, because there are a number of different cetacean populations on the decline right now,” said Bowles. “And where killer whales go, we can expect other small whale species to go — it’s a broader question.”

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2014/10/141007111055.htm  Original web page at Science Daily

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Dolphins are attracted to magnets: Add dolphins to the list of magnetosensitive animals, French researchers say

Add dolphins to the list of magnetosensitive animals, French researchers say. Dolphins are indeed sensitive to magnetic stimuli, as they behave differently when swimming near magnetized objects. So says Dorothee Kremers and her colleagues at Ethos unit of the Université de Rennes in France, in a study in Springer’s journal Naturwissenschaften — The Science of Nature. Their research, conducted in the delphinarium of Planète Sauvage in France, provides experimental behavioral proof that these marine animals are magnetoreceptive. Magnetoreception implies the ability to perceive a magnetic field. It is supposed to play an important role in how some land and aquatic species orientate and navigate themselves. Some observations of the migration routes of free-ranging cetaceans, such as whales, dolphins and porpoises, and their stranding sites suggested that they may also be sensitive to geomagnetic fields. Because experimental evidence in this regard has been lacking, Kremers and her colleagues set out to study the behavior of six bottlenose dolphins in the dolphinarium of Planète Sauvage in Port-Saint-Père. This outdoor facility consists of four pools, covering 2,000 m² of water surface. They watched the animals’ spontaneous reaction to a barrel containing a strongly magnetized block or a demagnetized one. Except from this characteristic, the blocks were identical in form and density. The barrels were therefore indistinguishable as far as echolocation was concerned, the method by which dolphins locate objects by bouncing sound waves off them. During the experimental sessions, the animals were free to swim in and out of the pool where the barrel was installed. All six dolphins were studied simultaneously, while all group members were free to interact at any time with the barrel during a given session. The person who was assigned the job to place the barrels in the pools did not know whether it was magnetized or not. This was also true for the person who analyzed the videos showing how the various dolphins reacted to the barrels.

The analyses of Ethos team revealed that the dolphins approached the barrel much faster when it contained a strongly magnetized block than when it contained a similar not magnetized one. However, the dolphins did not interact with both types of barrels differently. They may therefore have been more intrigued than physically drawn to the barrel with the magnetized block. “Dolphins are able to discriminate between objects based on their magnetic properties, which is a prerequisite for magnetoreception-based navigation,” says Kremers. “Our results provide new, experimentally obtained evidence that cetaceans have a magenetic sense, and should therefore be added to the list of magnetosensitive species.”

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2014/09/140929105237.htm Original web page at Science Daily

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Ecotourism rise hits whales

Whale-watching trips often come into very close contact with the animals. Boat trips to watch whales and dolphins may increasingly be putting the survival of marine mammals at risk, conservationists have warned. Research published this year shows that the jaunts can affect cetacean behaviour and stress levels in addition to causing deaths from collisions. But some animals are affected more than others and the long-term effects remain unclear, scientists at the International Marine Conservation Congress (IMCC) in Glasgow, UK, heard last week. “Whale-watching is traditionally seen as green tourism,” says wildlife biologist Leslie New of the US Geological Survey in Laurel, Maryland. “The negative is the potential for disturbance. That disturbance is a worry because we don’t want to do ‘death by 1,000 cuts’.” The number of people joining trips has expanded hugely since the 1990s, from 4 million in 31 countries in 1991 to 13 million in 119 countries in 2008, the most recent year for which full data are available. In 2008, the International Fund for Animal Welfare, an animal-protection charity in London, estimated the value of the industry at US$2.1 billion. Although collisions with boats can hurt the animals, researchers are more concerned about effects such as animals failing to feed or using up energy swimming away from the vessels. These seemingly small events can add up, studies suggest. Earlier this year, for example, marine biologist David Lusseau of the University of Aberdeen, UK, and his team showed that minke whales (Balaenoptera acutorostrata) in Faxaflói Bay in Iceland responded to whale-watching boats as they do to natural predators, upping their speed and respiring more heavily. But whether this was a direct result of the boats is difficult to pin down: Lusseau, who was not at the meeting, says that soon-to-be-published research by his team shows that behavioural changes are probably not affecting actual numbers of the minke in Faxaflói Bay. But Lusseau’s group has also shown that the bottlenose dolphins (Tursiops sp.) in Doubtful Sound, New Zealand, could be driven to extinction in decades. The large number of dolphin-watching trips in the sound is driving the animals away from their preferred areas and forcing them to avoid boats instead of feeding. Dolphin numbers declined from 67 in 1997 to 56 in 2005, the team found. Several delegates at the IMCC also described the effects on the roughly 70 endangered Irrawaddy dolphins (Orcaella brevirostris) living in the Mekong River between Cambodia and Laos, which are hounded by scores of tourist boats.

Determining which populations are most at risk could help to fix the problem, says Lusseau. He suggests plugging short-term observational data into longer-term population models to tease out whether behavioural changes are temporary or serious long-term threats. There are enough data on species types and locations to assess, at least roughly, where whale-watching should and should not be allowed, he says. But funding and political support are hampering the creation of detailed, localized plans. “There is a lot of lip service being paid to understanding the challenges tourism poses on wildlife, but in practice there is very little financial interest in finding this out,” he says.

http://www.nature.com/news/index.html Nature

http://www.nature.com/news/ecotourism-rise-hits-whales-1.15770  Original web page at Nature

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A whale with a distinctly human-like voice

For the first time, researchers have been able to show by acoustic analysis that whales — or at least one very special white whale — can imitate the voices of humans. That’s a surprise, because whales typically produce sounds in a manner that is wholly different from humans, say researchers who report their findings in the October 23 issue of Current Biology, a Cell Press publication. “Our observations suggest that the whale had to modify its vocal mechanics in order to make the speech-like sounds,” said Sam Ridgway of the National Marine Mammal Foundation. “Such obvious effort suggests motivation for contact.” It all started in 1984 when Ridgway and others began to notice some unusual sounds in the vicinity of the whale and dolphin enclosure. As they describe it, it sounded as though two people were conversing in the distance, just out of range of their understanding. Those unusually familiar sounds were traced back to one white whale in particular only some time later when a diver surfaced from the whale enclosure to ask his colleagues an odd question: “Who told me to get out?”

They deduced that those utterances came from a most surprising source: a white whale by the name of NOC. That whale had lived among dolphins and other white whales and had often been in the presence of humans. In fact, there had been other anecdotal reports of whales sounding like humans before, but in this case Ridgway’s team wanted to capture some real evidence. They recorded the whale’s sounds to reveal a rhythm similar to human speech and fundamental frequencies several octaves lower than typical whale sounds, much closer to that of the human voice. “Whale voice prints were similar to human voice and unlike the whale’s usual sounds,” Ridgway said. “The sounds we heard were clearly an example of vocal learning by the white whale.” That’s all the more remarkable because whales make sounds via their nasal tract, not in the larynx as humans do. To make those human-like sounds, NOC had to vary the pressure in his nasal tract while making other muscular adjustments and inflating the vestibular sac in his blowhole, the researchers found. In other words, it wasn’t easy.

Science Daily
November 13, 2013

Original web page Science Daily

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Building a bigger dolphin brain

In the world of big brains, humans have very few competitors. Dolphins come closest, with a brain to body weight ratio just below ours and just above chimpanzees. Now, a new analysis of these sharp swimmers reveals for the first time some of the genetic changes that led dolphins to evolve such large noggins. “Dolphins evolved from relatively small-brained animals like cows and hippos into this large-brained, highly specialized aquatic organism,” said Caro-Beth Stewart, an evolutionary biologist at the State University of New York, Albany, who was not involved in the research. “This is one of the first comprehensive studies to look at rates of molecular evolution in dolphins.” Nearly 50 million years ago, the ancestor of all cetaceans—a group that includes dolphins and whales—began its transition from land lubber to aquatic all-star. To do so, it had to evolve several adaptations: it lost limbs, it developed fins, and it gained the ability to hold its breath for long periods of time. Its brain also grew about three times bigger.

To get a sense of how these large brains evolved, Michael McGowen, an evolutionary biologist at Wayne State University in Detroit, Michigan, and his colleagues compared the dolphin’s genome with two of its closest land-loving, small-brained relatives, the cow and the horse, as well as the dog. Out of the roughly 10,000 protein-coding genes the researchers examined in the bottlenose dolphin genome, they identified 228 mutations that had swept through the population. Since the pressures of natural selection had encouraged the spread of these mutations through the species, the researchers surmised that these mutations were advantageous. Twenty-seven of these mutations were in proteins specifically associated with the nervous system, including transthyretin, which helps transport glucose across the blood-brain barrier, and microcephalin, which partly governs brain and head size. The researchers also found changes to several other genes that allowed neurons to form and break connections more easily, which is crucial to learning and higher cognitive functioning.

In addition, McGowen and colleagues discovered evidence for positive selection in genes affecting the cardiovascular system, which the authors believe were adaptations for carrying blood and oxygen to tissues during prolonged dives. They found additional changes to the small number of genes carried within the mitochondria, the cell’s powerhouses. These changes indicated a rise in metabolism, key to fuelling the energy-hungry brains, the team reports online today in the Proceedings of the Royal Society B. The physical changes required to adapt to life in the water appeared rather quickly, in roughly 5 million to 10 million years. McGowen and colleagues thought this would mean the dolphin’s genome would have rapid mutation rates, but they found the opposite. The dolphin genome had mutation rates much slower than expected. Interestingly, human genomes also show a similar slowdown in mutation rate. Although he is not yet sure why, McGowen hypothesizes that this slow mutation rate may somehow be a side effect of fast metabolisms and big brains. “Because dolphins have also evolved large brains, it gives us an example of the independent evolution of big, complex brains to compare to the evolution of the human brain,” says Stewart. “By doing this, you can find out what is necessary for a big brain.” For example, both humans and dolphins had mutations in the microcephalin gene, McGowen says, which seems to indicate that this gene may play an important role in determining brain size. He is currently examining the genomes of other animals to see if all large-brained mammals carry mutations in this gene. Other mutations, such as those boosting metabolism to fuel the brain, seem to show more variation, indicating that the outcome is more important than the specific genes involved.

ScienceNow
July 10, 2012

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New sensory organ found in rorqual whales

Scientists at the University of British Columbia and the Smithsonian Institution have discovered a sensory organ in rorqual whales that coordinates its signature lunge-feeding behaviour — and may help explain their enormous size. Rorquals are a subgroup of baleen whales — including blue, fin, minke and humpback whales. They are characterized by a special, accordion-like blubber layer that goes from the snout to the navel. The blubber expands up to several times its resting length to allow the whales to engulf large quantities of prey-laden water, which is then expelled through the baleen to filter krill and fish. The study, to be featured on the cover of the journal Nature, details the discovery of an organ at the tip of the whale’s chin, lodged in the ligamentous tissue that connects their two jaws. Samples were collected from recently deceased fin and minke whale carcasses captured as part of Icelandic commercial whaling operations. Commercial whaling in Iceland resumed in 2006 and quotas are determined annually by its government. Scanning of the whale’s chin revealed a grape fruit-sized sensory organ, located between the tips of the jaws, and supplied by neurovascular tissue.

The research team was assisted by technicians at FPInnovations, the owner of Canada’s only X-ray computed tomography (XRCT) machine large enough to accommodate the massive specimens. Used to scan giant logs, the XRCT machine provides a three dimensional map of the internal structure of whale tissues. “We think this sensory organ sends information to the brain in order to coordinate the complex mechanism of lunge-feeding, which involves rotating the jaws, inverting the tongue and expanding the throat pleats and blubber layer,” says lead author Nick Pyenson, a paleobiologist at the Smithsonian Institution, who conducted the study while a postdoctoral fellow at UBC. “It probably helps rorquals feel prey density when initiating a lunge.” A fin whale, the second longest whale on the planet, can engulf as much as 80 cubic metres of water and prey — equal or greater than the size of the whale itself — in each gulp in less than six seconds. A previous study by co-author Jeremy Goldbogen showed that a fin whale captures 10 kilograms of krill in each gulp in order to sustain its average 50-ton body mass. “In terms of evolution, the innovation of this sensory organ has a fundamental role in one of the most extreme feeding methods of aquatic creatures,” says co-author and UBC Zoology Prof. Bob Shadwick. “Because the physical features required to carry out lunge-feeding evolved before the extremely large body sizes observed in today’s rorquals, it’s likely that this sensory organ — and its role in coordinating successful lunging — is responsible for rorquals claiming the largest-animals-on-earth status,” Shadwick adds. “This also demonstrates how poorly we understand the basic functions of these top predators of the ocean and underlines the importance for biodiversity conservation.”

Science Daily
June 12, 2012

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Iconic marine mammals are ‘swimming in sick seas’ of terrestrial pathogens

Parasites and pathogens infecting humans, pets and farm animals are increasingly being detected in marine mammals such as sea otters, porpoises, harbour seals and killer whales along the Pacific coast of the U.S. and Canada, and better surveillance is required to monitor public health implications, according to a panel of scientific experts from Canada and the United States. UBC scientists Stephen Raverty, Michael Grigg and Andrew Trites and Melissa Miller from the California Department of Fish and Game, presented their research Feb 21 at the Annual Meeting of the American Association for the Advancement of Science (AAAS) in Vancouver, Canada. They called for stronger collaboration among public health, coastal water policy and marine mammal health research sectors to reduce land-sea transfer of pathogens and toxins. These terrestrial sourced pollutants are killing coastal marine mammals and likely pose risks to human health. Between 1998 and 2010, nearly 5,000 marine mammal carcasses were recovered and necropsied along the British Columbia and Pacific Northwest region of the U.S., including whales, dolphins and porpoises, sea lions and otters.

“Infectious diseases accounted for up to 40 per cent of mortalities of these marine animals,” says Stephen Raverty, a veterinary pathologist with the Animal Health Centre in the British Columbia Ministry of Agriculture and Lands, and an adjunct professor in UBC’s Marine Mammal Research Unit. “In many cases, the diseases found in these marine mammals have similar or genetically identical agents as those infecting pets and livestock. We don’t yet know how these diseases are affecting the health of marine mammals” says Raverty. For example, researchers recently identified the first case of Neospora caninum in sea otters. The parasite is known to cause infectious abortions in dairy cattle and muscular and bone diseases in dogs. Cryptococcus gatti, a fungus typically associated with dead and decomposing eucalyptus trees in tropical regions, has been found in some harbour and Dall’s porpoises. “The marine mammals that died of severe brain disease were infected with two common parasites, Toxoplasma and Sarcocystis, which are shed in the feces of feline and opossum hosts,” says Michael Grigg, a researcher with the U.S. National Institutes of Health’s Laboratory of Parasitic Diseases and adjunct professor in UBC’s Marine Mammal Research Unit. “Expansion of host range for the opossum and climate change may be important factors contributing to the increased incidence of infection from these land-based pathogens.”

“We can expect increased health risks for humans, pets and marine mammals sharing the same polluted marine habitat — including along the shorelines right here in downtown Vancouver,” says Andrew Trites, director of UBC’s Marine Mammal Research Unit. “In a way, marine mammals are the canary in the coal mine — we must consider ourselves warned and take appropriate action. The team recommends better management of urban pest populations, maintaining wetland marshes, reducing run-off from urban areas near the coast, and monitoring water quality to prevent pathogens and toxins from entering the marine food chain. Collaboration amongst coastal regions and countries is also crucial. “Marine mammals recognize no borders, and neither do pathogens and parasites,” says Raverty.

Science Daily
March 6, 2012

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Baby bumps slow dolphins down

For bottlenose dolphin moms-to-be, baby bumps are literally a drag. A new study shows that the animals pay a considerable price for their prenatal girth, which causes them to swim slower as they face more resistance from the water. The finding offers a first look at how pregnancy diminishes performance in cetaceans and may have implications for dolphin conservation efforts. Heavily pregnant bottlenose dolphins beat their tail fins faster (blue wavy line) and swim more slowly to compensate for increased drag. From scorpions to humans, most animals have a hard time getting around in late pregnancy. Past studies have found that altered or diminished physical performance before giving birth is common across species. Some birds are even rendered flightless shortly before they lay their eggs. But few studies have looked at why pregnancy changes performance. Biologist Shawn Noren of the University of California, Santa Cruz, didn’t intend to answer that question when she joined a pod of bottlenose dolphins at Dolphin Quest Hawaii, a marine research and public education center. She planned to focus on how newborn dolphins learn to swim. But with two of the center’s dolphins just 10 days from delivering their calves, Noren took the opportunity to examine their motion as well.

For most of 10 days, Noren sat submerged in the Dolphin Quest lagoon, becoming “one with the pod,” she says. Armed with SCUBA gear and a digital camcorder, she videotaped the pregnant dolphins as they swam parallel to her camera. She filmed them again after they gave birth, returning at regular intervals from one to 24 months later. Noren then combed through her hours of footage, digitally analyzing the movies to calculate the pre- and post-birth sizes of the dolphins, as well as their swimming speeds and movement patterns. She found that when the two dolphins had a bun in the oven, the frontal surface area—the surface of the animal that cuts through the water—increased 43% for one and 69% for the other. That extra area dramatically increased drag, meaning that a pregnant dolphin gliding at a comfortable 1.7 meters per second met with the same water resistance as a nonpregnant dolphin going twice as fast. In addition, the pregnant dolphins’ increased fat stores made them more buoyant, so the moms-to-be had to work harder to dive for prey.

The pregnant females’ tailbeat—their tail fins’ up-and-down motion as they swim—also changed, losing about 13% of its amplitude. To compensate, the moms beat their tail fins faster, but they still averaged only 38% of their post-pregnancy speeds, Noren reports today in the Journal of Experimental Biology. That pregnancy reduced performance isn’t surprising, says Noren, who admits she wondered why no one else had done such a study before. But the magnitude of the effect did surprise her. “It was definitely bigger than I had initially thought.” Marine biologist Frank Fish of West Chester University in Pennsylvania is also impressed. “Absolutely everything is impacted by these animals getting a bit thick in the middle,” says Fish, who was not involved in the study. “We always expected pregnancy would affect dolphins’ motion,” he says. “But no one up to this point had done the work to actually show there’s a hydrodynamic penalty for being pregnant.” That penalty could spell disaster when dolphins encounter predators and certain commercial fishing vessels, Noren says. In some places, tuna fishing involves chasing down the dolphins that often swim near tuna, catching both, and then releasing the dolphins. If trapped by such methods or by a predator, slower pregnant females would be less able to escape or catch up with their pod.

ScienceNow
December 13, 2011

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Dual parasitic infections deadly to marine mammals

A study of tissue samples from 161 marine mammals that died between 2004 and 2009 in the Pacific Northwest reveals an association between severe illness and co-infection with two kinds of parasites normally found in land animals. One, Sarcocystis neurona, is a newcomer to the northwest coastal region of North America and is not known to infect people, while the other, Toxoplasma gondii, has been established there for some time and caused a large outbreak of disease in people in 1995. Scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, collaborated with investigators in Washington state and Canada in the research, published online May 24 in the open-access journal PLoS Neglected Tropical Diseases. Toxoplasmosis, the illness caused by T. gondii infection, is generally not serious in otherwise healthy people, but the parasites can cause severe or fatal disease in people with compromised immune systems and can also damage the fetuses of pregnant women. The parasites are globally distributed and enter water via infected cat feces.

“Chlorination does not kill T. gondii, but filtration eliminates them from the water supply,” noted lead researcher Michael Grigg, Ph.D., of the NIAID Laboratory of Parasitic Diseases. Although S. neurona parasites do not infect people, other closely related species of Sarcocystis parasites do. “The public health message here is that people can easily avoid the parasites by filtering or boiling untreated water. Limiting serious disease in marine mammals, however, will require larger conservation efforts to block these land pathogens from flowing into our coastal waters.” During the six-year study period, more than 5,000 dead marine mammals were reported on the coastal beaches of the Pacific Northwest, Dr. Grigg said. Some deaths ascribed to parasitic encephalitis (brain swelling) were assumed to be caused by T. gondii, he noted, because the parasite can infect most mammals and was well established in the region. To determine the cause of death of the marine animals, Dr. Grigg collaborated with veterinary pathologist Stephen Raverty, D.V.M., Ph.D., of the British Columbia Ministry of Agriculture and Food and the University of British Columbia, and marine mammal researchers Dyanna Lambourn, of the Washington Department of Fish and Wildlife, and Jessica Huggins, of Cascadia Research Collective. Specimens were collected and animal autopsies (necropsies) conducted by members of the Northwest and British Columbia Marine Mammal Stranding Network.

Necropsies were performed on 151 marine mammals with suspected cases of parasitic encephalitis. The mammals included several kinds of seals and sea lions, Northern sea otters, a Pacific white-sided dolphin, porpoises and three species of whale. An additional 10 animals, all healthy adult California sea lions that were euthanized in the Columbia River to protect fish stocks, were included in the study as controls. Dr. Raverty’s group examined brain tissue from 108 animals positive for either S. neurona or T. gondii. They measured the number of parasites in the tissues and combined that with an assessment of the degree of brain inflammation to gauge whether the infection was likely to be the primary, contributing or incidental cause of death. At NIAID, Dr. Grigg and his team screened 494 brain, heart, lymph node and other tissue samples with a variety of genetic techniques. “Our techniques are unbiased in that we do not directly search for any particular species of parasite,” said Dr. Grigg. “Rather, the screens simply reveal evidence of any parasite in the tissue being studied.” The team then applied gene amplifying and gene sequencing methods to identify the species and, often, the subtype or lineage of the microbes. They found parasites in 147 of the 161 animals studied — 32 were infected with T. gondii, 37 with S. neurona and 62 with both parasites. The remaining 16 infections were caused by various other parasites, including several that had not been detected before in any kind of animal. Notably, all 10 healthy animals were infected with either one or both of the parasites.

“The presence of T. gondii did not surprise us, but the abundance of S. neurona infections was quite unexpected,” said Dr. Grigg. The researchers theorize that S. neurona has been introduced into the Pacific Northwest by opossums, which gradually have been expanding their range northward from California and can shed an infectious form of the parasite in their feces. The ample rainfall in the region provides an easy route for infected feces to enter inland and coastal waterways and then contaminate shellfish and other foods eaten by marine mammals. “The most remarkable finding of our study was the exacerbating role that S. neurona appears to play in causing more severe disease symptoms in those animals that are also infected with T. gondii,” said Dr. Grigg. Among animals for which necropsy had suggested parasitic infection as the primary cause of death, the co-infected animals were more likely to display evidence of severe brain tissue inflammation than those infected by either S. neurona or T. gondii alone. The two parasites are closely related, and other studies had suggested that a mammal’s acquired immunity after a first infection with one parasite might protect it from severe illness following infection by the other. However, that was clearly not the case in this study, noted Dr. Grigg. The study results also hinted that animals with lowered immunity, such as pregnant or nursing females or very young animals, were more likely to have worse symptoms when co-infected with both T. gondii and S. neurona. “Identifying the threads that connect these parasites from wild and domestic land animals to marine mammals helps us to see ways that those threads might be cut,” said Dr. Grigg, “by, for example, managing feral cat and opossum populations, reducing run-off from urban areas near the coast, monitoring water quality and controlling erosion to prevent parasites from entering the marine food chain.”

Science Daily
June 15, 2011

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Humpback whales’ dining habits — and costs

Some large marine mammals are known for their extraordinarily long dive times. Elephant seals, for example, can stay underwater for an hour at a time by lowering their heartbeat and storing large amounts of oxygen in their muscles. “Weighing up to 40 tons, humpback whales and their close relatives have relatively short dive times given their large body size,” says UBC zoology PhD candidate Jeremy Goldbogen, whose study is featured on the cover of the current issue of The Journal of Experimental Biology. “Our study suggests that this has to do with the enormous energy costs of its unique foraging behaviours.” Humpbacks belong to a group of whales – called rorquals – that includes the fin whale and the blue whale, the largest animal that has ever lived. Characterized by an accordion-like blubber layer that goes from the snout to the naval, these whales take deep dives in search of dense patches of tiny zooplankton, such as krill or copepods. While foraging, the whales literally drop their jaws during a high-speed dive – called a lunge – creating enormous drag akin to a race car driver opening a parachute. The drag forces the blubber to expand around a large volume of prey-laden water, which is then filtered out through a comb-like structure called baleen when the mouth closes.

Goldbogen and colleagues recorded the foraging behaviour of two humpback whales off the coast of California using a non-invasive, temporary digital tag that records depth, body angle and other acoustic data. After multiple tagging attempts, the team successfully recorded data over an eight-hour period; one whale performed 43 dives and 362 lunges while the other executed 15 dives and 89 lunges. The team found that lunge-feeding requires a large amount of energy compared to other behaviours – humpback whales breathe three times harder after returning to the surface from a foraging dive than from singing. Lunge-feeding whales also spent half as much time under water compared to singing whales. Not surprisingly, the team found that the longer the dive, the more lunges were taken – and more time and breaths were required before the next dive. The whales also stuck to the uppermost level of dense krill patches to maximize prey catch for its energy expenditure, according to the study. By integrating tag data and hydrodynamic theory inspired from parachute inflation studies, Goldbogen now plans to compare lunge-feeding performance among blue, fin and humpback whales to determine whether the energy cost of a lunge is higher for bigger rorquals. “We believe lunge feeding is related to the overall evolutionary and ecological success of rorquals, but the high energy cost may impose a physical limit on how big, and also how small, a whale can get.”

EurekAlert! Medicine
December 9, 2008

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Thinking ahead? An animal couldn’t do that, could it?

Many researchers working on animal cognition, however, believe that some species can indeed remember their past and plan for the future. Proving that this is the case is notoriously difficult. In studies of humans, memories and thoughts about the future are measured by asking the volunteer to verbalise what they are thinking or what motivated a decision. Animals, of course, cannot do the same, which makes it difficult to separate the repetition of a learned behaviour from evidence of true memory or planning. A key question is whether animals can recall experiencing an event at a specific time and place in a manner similar to human episodic memory. This is a major bone of contention in the debate. As Tulving saw it, human episodic memory requires self-awareness – the ability to imagine oneself in the past, as opposed to merely remembering what happened when and where. By this definition, the existence of animal episodic memory is virtually impossible to prove. Comparative psychologists who research animal memory, however, work on the basis of “episodic-like memory”. This requires only that the animal can remember what it did, where, and when.

Several studies have shown this to varying degrees. Animal trainers working with a pair of bottlenose dolphins, for example, have found that they are able to remember what they did in the immediate past. After being trained to perform dozens of different tricks in response to specific hand signals, the dolphins were asked, using another hand signal, to repeat the trick they last performed. Both dolphins could do this easily – one, a female called Elele, had a 100 per cent success rate. Similarly, experiments with pigeons and rats have shown that they are able to peck or nose at a particular symbol to indicate what behaviour they have just carried out.

New Scientist
November 25, 2008

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How to sex a dolphin

Assessing the ratio of males to females in endangered populations is vital for conservation work. But sexing a dolphin is tricky — not least because the crucial parts of the mammal are usually concealed beneath the waves. Researchers generally have to rely on time-consuming observations, either inferring a female’s sex from its close association with a calf, or noting genitalia when animals leap from the water or are captured on underwater video. The alternative is a biopsy that is potentially unpleasant for the animal. Lucy Rowe and Stephen Dawson, marine biologists at the University of Otago in Dunedin, New Zealand, have now come up with a accurate alternative that could spare their fellow researchers, and the dolphins, this inconvenience. In a recently published paper in Marine Mammal Science the pair report successfully using fin photographs to determine the sex of bottlenose dolphins in a well-studied population in New Zealand’s Doubtful Sound. “Our technique allows bottlenose dolphins to be sexed from characteristics measured solely from dorsal fin identification photographs, which are routinely collected as part of non-invasive population monitoring,” Rowe and Dawson told Nature News in an email.

The pair teamed an over-the-counter digital camera with a pair of laser pointers, which project two reference spots precisely 10 centimetres apart onto the fin, allowing an accurate determination of its size. After taking a series of digital photographs of the Doubtful Sound dolphins, the authors compared them with existing fin and sex records for the population. Rowe and Dawson found that male fins had significantly more scars than female fins, probably as a result of fighting. Male fins had a median of 15% scar tissue, whereas in females this was just 3.9%. Conversely, female fins tended to have a greater number of patchy skin lesions than male fins, with a median of 12.1% coverage compared with males’ 6.8%. The two then used a statistical analysis of scarring, number of fin nicks and fin size to correctly predict the sex of 93% of the 43 dolphins in the group. This laser-sighted technique could potentially be applied to other, less-studied populations of dolphin or even to other species, the scientists say.

“The best candidates are species in which there is slight sexual dimorphism, but not enough to reliably sex individuals without a photogrammetric tool,” say Rowe and Dawson. “There are many long-term cetacean research projects that conduct photo-identification and have gathered sex data on a number of individuals. It may be possible to use those photographs to develop a species-specific sex-classification model following the technique we used.” The authors are currently applying their technique to another population of dolphins in the nearby Dusky Sound, and “initial signs are good”. Shannon Gowans, a dolphin researcher at Eckerd College in St. Petersburg, Florida, and the associate editor at Marine Mammal Science responsible for the paper, says, “If it’s applicable to other populations it would be very helpful. In the population I work with, very few of these individuals have been sexed. If this kind of thing applies far beyond this one population it would be great.”

Nature
October 28, 2008

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Beaked whales actually hear through their throats

Researchers from San Diego State University and the University of California have been using computer models to mimic the effects of underwater noise on an unusual whale species and have discovered a new pathway for sound entering the head and ears. Advances in Finite Element Modeling (FEM), Computed tomography (CT) scanning, and computer processing have made it possible to simulate the environment and anatomy of a Cuvier’s beaked whale when a sonar signal is sent out or received by the whale. The research paper is a catalyst for future research that could end years of speculation about the effects of underwater sound on marine mammals.

FEM is a technique borrowed from engineering used, for example, to simulate the effect of an earthquake on a building. By inputting the exact geometry and physical properties of a building the effect of forces such as an earthquake, or in this case noise vibrations, can be accurately predicted. Dr Cranford of San Diego State University triggered the research into Cuvier’s beaked whales almost ten years ago when he undertook the first ever CT scan of a large whale, which provided researchers with the very complex anatomic geometry of a sperm whale’s head. Dr Cranford said, “I think that the methods developed for this research have the potential to revolutionize our understanding of the impact of noise on marine organisms.”

Since 1968, it has been believed that noise vibrations travel through the thin bony walls of toothed whales’ lower jaw and onto the fat body attached to the ear complex. This research shows however that the thin bony walls do not transmit the vibrations. In fact they enter through the throat and then pass to the bony ear complex via a unique fatty channel. Despite the Cuvier’s beaked whale being a rare and little-known specie, Dr Cranford and his team started the work on it because over recent years there have been instances when this type of whale has stranded after exposure to intense sound, making them an ideal starting point for research into underwater communication.

Science Daily
February 19, 2008

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Newborn dolphins go a month without sleep

Newborn dolphins and killer whales do not sleep for a whole month after birth, new research has revealed, and neither do their mothers, who stay awake to keep a close eye on their offspring. The feat of wakefulness is remarkable given that rats die if forcibly denied sleep. And in humans, as any new parent will tell you, sleep deprivation is an exquisite form of torture. The surprising sleeping patterns of captive killer whales – Orcinus orca – and bottlenose dolphins – Tursiops truncates – in the early months of life were observed by a team led by Jerome Siegel of the University of California at Los Angeles, US. Unlike all animals previously studied, which maximise rest and sleep after birth to optimise healthy growth and development, the cetaceans actively avoided shut-eye. “The idea that sleep is essential for development of the brain and body is certainly challenged,” says Siegel.

The patterns observed contrast with that seen in adult cetaceans, which normally “sleep” for 5 to 8 hours a day – either floating at the surface or lying on the bottom before rising periodically for air. But the newborn whales and dolphins were continually active, surfacing for air every 3 to 30 seconds. They also kept at least one eye open to track their mothers, who seemed to set the frenetic pace by always coursing ahead of their offspring. Siegel and his colleagues found that, over months, mothers and offspring gradually increased the amount of rest until it approached that of normal adults. And measurements of the stress hormone cortisol showed that levels were normal, so the animals were not apparently stressed by their insomnia.

The researchers suggest that for cetaceans, the ability to keep on the go after birth has several advantages. It makes it harder for predators to catch them because “in the water, there’s no safe place to curl up”, Siegel notes. It also keeps their body temperature up while their layer of insulating blubber builds up. The mystery, he says, is how the cetaceans seem to avoid the penalties of sleep deprivation seen in all other mammals. “It’s an extraordinary finding,” says Jim Horne, director of the Sleep Research Centre at the University of Loughborough, UK. “Normally, newly born mammals and their mothers stay asleep for as long as they can after birth.” Horne says that if it had been practically possible, measurement of brain activity would have provided better confirmation that the animals were awake than simply checking if they had at least one eye open. “You can’t be entirely sure that they’re actively awake all the time, not going into a drowsy, trance-like state,” he says. “But they are certainly showing extensive periods of wakefulness.” Horne says that humans sometimes fall asleep with their eyes open, so it is conceivable that nature allows the dolphins and whales to do the same.

New Scientist
July 19, 2005

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Australian dolphins learn to hunt with sponges stuck to their noses

Bottlenose dolphins are known to be smart, but a study of tool use has emphasized just how clever these mammals can be. Female dolphins in an Australian bay seem to be learning from their mothers how to stick marine sponges on their noses to help them hunt for fish, researchers say. “It is the first documented case of tool use in a marine mammal,” says Michael Krützen of the University of Zurich, Switzerland, who led the study into how the trick is passed from one generation to the next. Rather than being an inherited trait, the tool use is probably being learned by daughter dolphins from their mothers, the researchers report in the Proceedings of the National Academy of Sciences.

Sponge-using dolphins (Tursiops truncatus) were first described in 1997 in Shark Bay, 850 kilometres north of Perth, Australia. Since then, all dolphins known to use this tool have come from the same bay, and the vast majority have been female. Direct observations have been rare, but researchers think the dolphins use the marine sponges to disturb the sandy sea bottom in their search for prey, while protecting their beaks from abrasion.

The knack of learning to use tools from fellow creatures is thought to be very rare. Chimpanzees (Pan troglodytes) have been seen to use two stones to crack open nuts, for instance, and this is thought to be a culturally acquired trait. In other instances tool use seems to be inherited. New Caledonian crows (Corvus moneduloides), for example, use twigs to gain access to food in nooks and crannies of trees, and can do so without having been taught by another crow.

To see whether the dolphin behaviour was inherited, Krützen and his colleagues analysed DNA from 13 spongers, only one of which, Antoine, was male, and from 172 non-spongers. They found that most spongers shared similar mitochondrial DNA, which is genetic information passed down from the mother. This indicates that the spongers are probably all descended from a single “Sponging Eve”. The spongers also shared similar DNA from the nucleus, suggesting that Eve lived just a few generations ago. But not all the female dolphins with similar mitochondrial DNA use sponges. And when the researchers considered ten different means of genetic inheritance, considering that the sponging trait might be dominant, recessive, linked to the X-chromosome or not, they found no evidence that the trait was carried in DNA. “It’s highly unlikely that there is one or several genes that causes the animals to use tools,” says Krützen.

Andrew Whiten, a researcher who studies cultural tradition in chimpanzees at the University of St. Andrews, UK, says the work is very thorough. “Krützen and his colleagues have done a painstaking genetic analysis,” says Whiten. But he cautions that there is as yet no evidence that dolphins can pick up tool use by observation. Krützen points out that young dolphins spend up to four or five years with their mother, giving them lots of time to pick up the trick. “We know they are seeing it all the time,” says Janet Mann, a co-author of the study from Georgetown University in Washington DC. In general, dolphins are known to imitate each other very well, Krützen adds.

Mann says the males probably learn sponging from their mothers as well, but do not engage in it when older, perhaps because they are too busy pursuing fertile females to engage in complicated foraging. She hopes to catch the dolphins in the act of learning sponge use from their mothers soon. Krützen plans to study whether the sponge users have any advantage over non-spongers. A preliminary study of the fat content in dolphin blubber suggest that spongers get food that other animals do not, Krützen says.

Nature
June 21, 2005

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Exceptional whale fossil found in Egyptian desert

An American paleontologist and a team of Egyptians have found the most nearly complete fossilized skeleton of the primitive whale Basilosaurus isis in Egypt’s Western Desert, a university spokesman said on Monday. Philip Gingerich of the University of Michigan excavated the well-preserved skeleton, which is about 40 million years old, in a desert valley known as Wadi Hitan (the Valley of the Whales) southwest of Cairo, spokesman Karl Bates told Reuters. “His feeling is that it’s the most complete — the whole skeleton from stem to stern,” said Bates. The skeleton, which is 50 feet long, could throw light on why there are so many fossilized remains of whales and other ancient sea animals in Wadi Hitan and possibly how the extinct animal swam, he said.

Basilosaurus isis is one of the primitive whales known as archaeocetes, which evolved from land mammals and later evolved into the two types of modern whale. But it looks like a giant sea snake and the paleontologists who found the first archaeocetes thought they were reptiles. Modern whales swim by moving their horizontal fluke up and down in the water, while fish swim by lateral undulations. “The research team will use the new skeleton to study how it lived and swam, and possibly to learn why it so abundant in Wadi Hitan,” Gingerich said in a statement. The statement said the skeleton will go to Michigan for preservation and replication. The original will then come back to Egypt for display.

Wadi Hitan is unusually rich in fossil remains from the period, trapped in a sandstone formation that then formed the sea bed. The fossils include five species of whale, three species of sea cow, two crocodiles, several turtles, a sea snake, and large numbers of fossilized sharks and bony fish.
It is a protected area to be developed as a national park under an Italian-Egyptian cooperative program and it has been nominated as a UNESCO World Heritage site because of its natural beauty and scientific importance.

Yahoo
May 24, 2005

Original web page at Yahoo

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Scientists artificially inseminate whale

After bringing in a parade of males and watching for years as nature never took its course, scientists at Mystic Aquarium have performed what is believed to be the first artificial insemination of a beluga whale. Aquarium scientists, with help from their peers at Sea World, artificially inseminated Kela, a 24-year-old beluga. After giving the whale hormones to induce the release of an egg into the reproductive tract, workers used a crane to lift Kela out of the water and place her on a mat. Frozen sperm from a Sea World beluga was then inserted. The process took only a few minutes.

Scientists plan to use ultrasound and blood tests over the next few days to monitor the 1,156-pound whale with the hope that the procedure worked. Beluga whales have been born in captivity, but never through artificial insemination. Kela would deliver a calf in about 14 months if the procedure was successful, but scientists believe there is only a slim chance of that happening. That is because little is known about beluga reproduction, said Todd Robeck, a veterinarian and reproductive physiologist from Sea World in San Antonio, Texas. “We don’t know whether it will work or won’t work, but things went well,” he told The Day of New London, moments after placing thawed sperm inside Kela with an endoscope.

Tracy Romano, the aquarium’s director of research and veterinary services, said the birth of a new beluga may not happen because many things can go wrong. “It’s mostly a learning experience and to get information for the future,” she said. There are about 30 belugas in captivity.
Aquariums and water parks across the country want to increase that number. Because it is difficult to get permits to capture wild belugas, the focus has shifted to trying to breed them in captivity. This has meant moving whales from one location to another, which can be stressful for them.

Scientists say it would be better to inseminate whales with sperm that can be shipped around the country. They say the work will help them learn about how wild belugas breed and how to better protect them. Robeck has been successful in attempts to artificially inseminate killer whales and dolphins. He and other scientists spent the past three years doing research in preparation for the procedure.

Kela and Naku, the aquarium’s female belugas, were not ideal candidates for the procedure because neither had ever been pregnant and because of their advanced age, Robeck said. However, they are extremely well trained, which made the procedure easier. “There is just an incredible amount of variables involved in this,” said Gerard Burrow, president and chief executive officer of the aquarium. “But it’s really important for us to understand the reproduction of these animals.”

Yahoo
April 12, 2005

Original web page at Yahoo