Category: Environment

{Noise from motorboats is making fish become bad parents, and reducing the chance of their young surviving, research led by marine experts at the University of Exeter has shown.}

The sound of motorboat engines disturbed coral reef fish so acutely it changed the behaviour of parents, and stopped male fish properly guarding their young, feeding and interacting with their offspring.

The research, which involved playing recordings of natural reef noise or intermittent motorboat noise around 38 fish nests over 12 days, found that the death-rates of baby fish exposed to boat engine noise increased significantly, with six of the 19 boat-noise nests suffering complete mortality.

The Exeter University led team of marine biologists say that noise from boats is a ‘global pollutant’, distracting fish and making them unable to properly protect their young from predators. They believe motorboat noise should be factored in when trying to protect fish stocks and manage fisheries.

Dr Steve Simpson, an expert of the impact of noise on marine life at the University of Exeter.

“This study raises important implications for managing the noise of the 100,000s of motorboats used around the world in coral reef environments. We are now considering acoustic quiet zones and corridors, and exploring how engine and propeller development can reduce the impact of this globally prevalent pollutant.”

The University of Exeter researchers predicted that their field research into the effect of human-made noise on coral fish could have wider implications for the survival of other marine species, and even birds and mammals. They called for more research in these areas.

Dr Sophie Nedelec, of the College of Life and Environmental Sciences at the University of Exeter, said she believed other species could be similarly affected by marine noise pollution.

“Parental care is widespread in the animal kingdom; from blue tits to blue whales, so there could be big implications for populations of animals affected by noise,” she said.

Noise from boats and has already been shown to affect the way fish, mammals, birds and invertebrates behave. It can force them to change their habitat to get away from the noise and reduce their success finding a mate. Boat noise can travel for many kilometres underwater.

This new research, carried out by the University of Exeter, University of Bristol, James Cook University, Queensland, Australia, and the Australian Institute of Marine Science, showed motorboat noise can increase death rates among juvenile fish.

Dr Nedelec, lead author on the paper published in Proceedings of the Royal Society B journal, added:

“Parental care behaviour seems to be impaired in noisy conditions and we believe this makes it easier for predators to strike their offspring. It is likely the parents were either stressed or distracted by the noise, giving an advantage to the predators in this case.”

The researchers made observations for 12 days of 38 natural nests with broods of young in the Great Barrier Reef in Australia. It found that exposure to recordings of noise from motorboats, compared to ambient sounds, had a noticeable impact on the survival of baby coral reef fish, and the behaviour of adult male fish.

Motorboat noise is the most common source of human-made noise in shallow reef environments. The University of Exeter scientists warned that because they broadcast the motorboat engine noise through underwater loudspeakers which do not broadcast the full range of sounds produced by motorboats their results could be conservative.

The males and female spiny chromis, a coral reef fish which lives in the tropical Western Pacific, bring up their offspring together, with males contributing more care than females of the species.

Fish exposed to the motorboat noise spent far more time chasing and making aggressive strikes at other fish, compared to males exposed to recordings of ambient sound. The scientists believe this increase in aggressive behaviour may have been be due to ‘heightened stress’, or distraction by the noise which led to decision-making errors, so the fish attacked or chased fish that were not a predatory threat.

The greater time spent “chasing inappropriate species at inappropriate times” also meant father fish spent less time near the nest, which may have left their offspring vulnerable to attacks from predators.

Adult fish exposed to the motorboat noise also spent less time feeding, which would have been likely to reduce their physical condition.

Another coral reef fish, the longear sunfish, was observed to move away from their nest when a slow-moving motorboat was nearby. Predators that have located a nest they can feed from are likely to return to hunt.

Other studies have shown that spawning could be interrupted by the approach of a fast moving powerboat.

Professor Andy Radford, University of Bristol, said: “Experiments that measure survival in natural conditions — as we have done in this study — are crucial if we are to understand fully the impact of anthropogenic noise.”

Source:Science Daily

{At the Triassic-Jurassic boundary, 200 million years ago, some 60% of species living on Earth disappeared. Scientists suspected that magmatic activity and the release of CO2 were responsible for this environmental disaster. To corroborate this, one would need to find and to precisely date traces of this activity and make sure that it coincides with this mass extinction. The precise determination of this timing has been achieved by scientists at the University of Geneva, and is published in Nature Communications.}

Scientists have often linked the annihilation of life at the Triassic-Jurassic boundary with the emission of gas during the volcanic activity of the Central Atlantic Magmatic Province, a huge volcanic province that erupted around the same time. Geological studies, however, have questioned this hypothesis since the flood basalt eruptions from the igneous province are too young to be responsible for the mass extinction. The scientists, among them a team from UNIGE, therefore went to look for traces of magmatic activity that may be older, proving the role of magmatic activity in mass extinctions that hit the history of Earth during this period of time.

The geologists identified large areas covered by flood basalts assigned to the Central Atlantic Magmatic Province (CAMP), which extends over several million km2 from Northern to Southern America, and from Europe to Africa. They also discovered vertical fissures that extend over hundreds of kilometres and large intrusions. “We therefore erected the hypothesis that these fissures and intrusions are older or coeval to the mass extinction at the Triassic-Jurassic boundary, and we have verified this applying our high-precision dating techniques,” explains Joshua Davies, research fellow at the Department of Earth Sciences of the Faculty of Science at the University of Geneva (UNIGE).

The basalts enclose the mineral zircon in tiny quantities, which itself contains uranium. Uranium has the particularity of disintegrating itself over time into lead at a known rate. “It’s because of this, by measuring relative concentrations of uranium and lead, we can determine the age of crystallization of minerals in a rock to about 30’000 years, which is extremely precise for a period of time 200 million years ago,” adds Urs Schaltegger, professor at the Department of Earth Sciences of the Faculty of Science at the University of Geneva (UNIGE).

To carry out precise age determinations is a complicated exercise, only around four laboratories are capable of at this level of precision, among them the laboratory at UNIGE. The geologists were particularly interested to date basalts that can be found in the Amazonian sedimentary basin, an huge reservoir of coal and oil. And indeed, the results of their age determinations confirm that the age of these basalts correlates with the mass extinction at the Triassic-Jurassic boundary. This result allows the scientists to link this magmatic activity with the thermally induced release of immense volumes of CO2 originating from coal and hydrocarbons which likely caused the climate change the drove the disappearance of 60% of the species that were living at this time.

Source:Science Daily

{For the first time, researchers have shown that a marine birds can hear under water. This offers new possibilities for the protection of marine birds in trafficked waters. Seals, whales and other marine animals can hear under water. The cormorant also has this ability, which new research from University of Southern Denmark (SDU) shows.}

According to the biologists it makes good sense, that cormorants can hear under water — the environment where it finds most of its food.

About every tenth bird species — ca. 800 species — in the world hunts under water, and it may turn out that they too can also hear under water.

{{The sound of fish}}

Researchers Kirstin Anderson Hansen, Alyssa Maxwell, Ursula Siebert, Ole Næsbye Larsen and Magnus Wahlberg from the Department of Biology at University of Southern Denmark have tested the cormorant, Loke’s, hearing. Loke lives at SDU’s marine biology research station in the Danish town Kerteminde.

“Hearing under water must be a very useful sense for cormorants. They depend on being able to find food, even if the water is not clear, or if they live in the Arctic regions where it is dark for long periods at a time,” says Kirstin Hansen, Ph.D.

Loke’s hearing abilities are on a par with the hearing of the toothed whale and the seal.

{{The sound of humans}}

He can hear sounds ranging between 1 and 4 kHz, and it is in this range that fish such as sculpin and herring produce sounds. Both sculpin and herring are on the cormorant’s menu.

1 — 4 kHz is not only the range in which fish sounds are found. There are also various human-made sounds found in this range.

“Human-made sounds can disturb the ocean’s animals to such an extent that they cannot find food or communicate with each other. It is a known problem for porpoises and seals for instance, and now it is also a potential problem for birds. It is certainly something that we should be more aware of, says Magnus Wahlberg, Associate Professor.

Human-made sounds can be everything from spinning wind turbines and ship traffic to water scooters and drilling platforms.

The SDU biologists are now planning more trials, and the next birds to be tested will probably be the common murres and puffins.

Source:Science Daily

{A long-lasting lake on ancient Mars provided stable environmental conditions that differed significantly from one part of the lake to another, according to a comprehensive look at findings from the first three-and-a-half years of NASA’s Curiosity rover mission. While previous work had revealed the presence of a lake more than three billion years ago in Mars’ Gale Crater, this study defines the lake’s chemical conditions and uses Curiosity’s powerful payload to determine that the lake was stratified.}

Stratified bodies of water exhibit sharp chemical or physical differences between deep water and shallow water. In Gale’s lake, the shallow water was richer in oxidants than deeper water was.

“We’re learning that in parts of the lake and at certain times, the water carried more oxygen,” said Roger Wiens, a planetary scientist at Los Alamos National Laboratory and co-author of the study, published today in the journal Science. “This matters because it affects what minerals are deposited in the sediments, and also because oxygen is important for life. But we have to remember that at the time of Gale Lake, life on our planet had not yet adapted to using oxygen — photosynthesis had not yet been invented. Instead, the oxidation state of certain elements like manganese or iron may have been more important for life, if it ever existed on Mars. These oxidation states would be controlled by the dissolved oxygen content of the water.”

“These were very different, co-existing environments in the same lake,” said Joel Hurowitz of Stony Brook University, lead author of the report. “This type of oxidant stratification is a common feature of lakes on Earth, and now we’ve found it on Mars. The diversity of environments in this Martian lake would have provided multiple opportunities for different types of microbes to survive.”

Whether Mars has ever hosted any life is still unknown, but seeking signs of life on any planet, whether Earth, Mars or more-distant icy worlds, begins with reconstruction of the environment to determine if it was capable of supporting life. NASA is using Curiosity to explore habitable environments on the ancient surface of Mars.

Over more than 1,700 sols (martian days, which are 24 hours, 39 minutes long), Curiosity has traveled more than 16 km from the bottom of Gale crater part way up Mount Sharp near the center of the crater. Los Alamos National Laboratory developed the laser-shooting Chemistry and Camera (ChemCam) instrument that sits atop Curiosity in conjunction with the French space agency. Los Alamos’ work on discovery-driven instruments like ChemCam stems from the Laboratory’s experience building and operating more than 500 spacecraft instruments for national security. Scientists are using all the data collected by ChemCam and other on-board instruments to put together a more complete picture of the geological history of Mars.

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Source:Science Daily

{Like people, the birds ‘trade’ vocal cues to distinguish ‘d’ from ‘t’}

No experience with human speech is necessary for budgerigars to perceive the difference between “d” and “t,” according to a study published May 31, 2017 in the open-access journal PLOS ONE by Mary Flaherty from The State University of New York, Buffalo, USA, and colleagues.

The debate over speech perception is unresolved, with some evidence supporting a speech-specific mechanism and other evidence supporting a general auditory mechanism. The latter case holds that, in the absence of extensive experience with speech, there should be no difference between speech and nonspeech perception. To investigate this scenario, Flaherty and colleagues used budgerigars, vocal mimics that are similar to people in their ability to perceive consonant and vowel tokens. The researchers divided 25 budgerigars into groups before hatching, raising some in complete isolation from human speech and others with extensive exposure to human speech.

After the birds fledged, the researchers trained them to peck keys in response to synthetic speech sounds that began with “d” or “t.” Then they tested the birds’ perception of speech sounds that varied in two cues: voice onset time and the frequency of the first formant (formants are resonating frequencies of the vocal tract). For comparison, they likewise tested the perception of speech sounds in 25 people.

The researchers found that, much like people, the budgerigars “traded cues” that is, offset changes in one cue with those in another when perceiving speech sounds. For example, when the first formant frequency differed, the birds identified “d” when the voice onset time was short and “t” when it was long. Moreover, the observed cue trading did not depend on prior experience with speech. These findings support a general auditory mechanism for speech perception rather than one that is speech-specific.

“Regardless of their experience with speech sounds — whether completely isolated from human speech for their whole lives or trained extensively to mimic speech — the birds in our study used speech cues in a manner very similar to humans,” says Flaherty. “To the extent that birds can be used as a model for speech perception, these results indicate that prior experience with speech sounds is not a prerequisite for speech perception.”

Source:Science Daily

{How do baboons succeed in coordinating the movements of their group? Biologists at the University of Konstanz study these organisms in the wild to find out which behavioural rules baboons use when interacting with others. Konstanz researchers have found out that the animals only need a few simple rules to coordinate their group movements, enabling them to organise themselves, and to make decisions, without splitting. In four recent research publications — published in the journals Science, Scientific Reports, eLife and the Proceedings of the Royal Society B — the Konstanz scientists paint a new picture of group dynamics among baboons with unprecedented detail by tracking how individuals make decisions within a group. Research partners were the Max Planck Institute for Ornithology, the Smithsonian Tropical Research Institute in Panama as well as Princeton University, the University of California, Davis, and the University of Illinois at Chicago (all USA).}

Baboons have long been studied because they have a highly complex social structure, forming groups from 20 to over 100 individuals. Such social structure suggested to early biologists that baboons must employ high levels of cognition to be able to coordinate their behaviour with so many group mates. For example, classical theories on group coordination among baboons suggested that the larger, grown-up individuals should stay at the periphery of the group to protect younger and weaker animals in the centre. However, to constantly keep up this positioning, each baboon would need to know, at all times, where the other members of the group are. Konstanz biologists have now demonstrated that this is not necessarily the case — neither is there a need for it. “Actually, coordinating their movement with only a few neighbouring individuals can generally be enough for animals to keep their group together, and what we see in the baboons is consistent with this idea,” explains biologist Dr. Ariana Strandburg-Peshkin. Mathematics can further explain how individuals maintain specific positions within the group (either close to the center, at the front, back, or at the periphery) as her colleague Dr. Damien Farine explains: “If a baboon tries to stay together with only a slightly larger number of neighbouring individuals, this baboon will automatically move closer to the centre of the group. By contrast, individuals that coordinate their positions with a smaller number of fellow group members will end up at the group’s periphery.”

This means that the neighbourhood size, i.e. the number of members in the neighbourhood an animal stays together with, is decisive for maintaining the group structure. “This simple rule makes it possible to consistently describe the movements of the baboons. Consequently, the group structure results from local behavioural principles of individual animals and not from a joint decision taken by the entire group,” says Professor Iain Couzin (University of Konstanz and Max Planck Institute for Ornithology), adding: “We also observe that the movement rules of baboons, and how they make decisions, very much resembles the decision processes found in schools of fish and flocks of birds.”

For their research the biologists studied a group of 25 baboons living in the wild in Kenya — a complex project headed by Professor Margaret Crofoot (University of California, Davis). A GPS transmitter provided locations of the individual animals, second-by-second, for two weeks. The scientists combined the movement data of the animals with remote images of the three-dimensional environment and vegetation structure recorded by a drone to obtain an overall picture of the surrounding conditions.

The evaluation of these data provides new insights into the collective behaviour of the baboons. In a series of publications, the researchers have also examined group dynamics and factors that influence the movements of individual animals of the group, and ultimately determine the entire group structure. The inclination to follow other group members is the strongest factor driving the decision-making behaviour of baboons. For example, baboons prefer paths that other group members have taken shortly before. The more baboons use a certain path, the more attractive it becomes for the others. In situations where they need to decide in which direction to move, if several members of the group head in different directions, baboons are inclined to follow the majority (i.e. the direction where most of their group mates are headed).

“Together, these studies capture new insights into how baboons make decisions. No longer do we believe that a single dominant male leads the troop, deciding on behalf of everyone,” says Damien Farine. Instead, University of Konstanz researchers have revealed that baboon life is much more democratic, and that many of the complex behaviours they exhibit might actually be the outcome of simple behavioural rules, potentially allowing individuals to spend more time thinking about other things — such as looking out for predators.

Source:Science Daily

{An international team of scientists has found evidence suggesting the dehydration of minerals deep below the ocean floor influenced the severity of the Sumatra earthquake, which took place on December 26, 2004.}

The earthquake, measuring magnitude 9.2, and the subsequent tsunami, devastated coastal communities of the Indian Ocean, killing over 250,000 people.

Research into the earthquake was conducted during a scientific ocean drilling expedition to the region in 2016, as part of the International Ocean Discovery Program (IODP), led by scientists from the University of Southampton and Colorado School of Mines.

During the expedition on board the research vessel JOIDES Resolution, the researchers sampled, for the first time, sediments and rocks from the oceanic tectonic plate which feeds the Sumatra subduction zone. A subduction zone is an area where two of the Earth’s tectonic plates converge, one sliding beneath the other, generating the largest earthquakes on Earth, many with destructive tsunamis.

Findings of a study on sediment samples found far below the seabed are now detailed in a new paper led by Dr Andre Hüpers of the MARUM-Center for Marine Environmental Sciences at University of Bremen – published in the journal Science.

Expedition co-leader Professor Lisa McNeill, of the University of Southampton, says: “The 2004 Indian Ocean tsunami was triggered by an unusually strong earthquake with an extensive rupture area. We wanted to find out what caused such a large earthquake and tsunami and what this might mean for other regions with similar geological properties.”

The scientists concentrated their research on a process of dehydration of sedimentary minerals deep below the ground, which usually occurs within the subduction zone. It is believed this dehydration process, which is influenced by the temperature and composition of the sediments, normally controls the location and extent of slip between the plates, and therefore the severity of an earthquake.

In Sumatra, the team used the latest advances in ocean drilling to extract samples from 1.5 km below the seabed. They then took measurements of sediment composition and chemical, thermal, and physical properties and ran simulations to calculate how the sediments and rock would behave once they had travelled 250 km to the east towards the subduction zone, and been buried significantly deeper, reaching higher temperatures.

The researchers found that the sediments on the ocean floor, eroded from the Himalayan mountain range and Tibetan Plateau and transported thousands of kilometres by rivers on land and in the ocean, are thick enough to reach high temperatures and to drive the dehydration process to completion before the sediments reach the subduction zone. This creates unusually strong material, allowing earthquake slip at the subduction fault surface to shallower depths and over a larger fault area – causing the exceptionally strong earthquake seen in 2004.

Dr Andre Hüpers of the University of Bremen says: “Our findings explain the extent of the large rupture area, which was a feature of the 2004 earthquake, and suggest that other subduction zones with thick and hotter sediment and rocks, could also experience this phenomenon.

“This will be particularly important for subduction zones with limited or no historic subduction earthquakes, where the hazard potential is not well known. Subduction zone earthquakes typically have a return time of a few hundred to a thousand years. Therefore our knowledge of previous earthquakes in some subduction zones can be very limited.”

Similar subduction zones exist in the Caribbean (Lesser Antilles), off Iran and Pakistan (Makran), and off western USA and Canada (Cascadia). The team will continue research on the samples and data obtained from the Sumatra drilling expedition over the next few years, including laboratory experiments and further numerical simulations, and they will use their results to assess the potential future hazards both in Sumatra and at these comparable subduction zones.

Source:Science Daily

{In dry southern Morocco, domesticated goats climb to the precarious tippy tops of native argan trees to find fresh forage. Local herders occasionally prune the bushy, thorny trees for easier climbing and even help goat kids learn to climb. During the bare autumn season, goats spend three quarters of their foraging time “treetop grazing.”}

Spanish ecologists have observed an unusual way in which the goats may be benefiting the trees: the goats spit the trees’ seeds. Miguel Delibes, Irene Castañeda, and José M Fedriani reported their discovery in the latest Natural History Note in the May issue of the Ecological Society of America’s journal Frontiers in Ecology and the Environment. The paper is open access.

Argan may be familiar from popular beauty products that feature argan oil, made from the tree’s nuts. The nut is surrounded by a pulpy fruit that looks a bit like a giant green olive. For goats, the fruits are a tasty treat worth climbing up to 30 feet into the branches to obtain.

But the goats don’t like the large seeds. Like cows, sheep, and deer, goats re-chew their food after fermenting it for a while in a specialized stomach. While ruminating over their cud, the goats spit out the argan nuts, delivering clean seeds to new ground, wherever the goat has wandered. Gaining some distance from the parent tree gives the seedling a better chance of survival.

This novel seed dispersal effect is a variation on the mechanism ecologists call endozoochory, in which seeds more commonly pass all the way through the animal’s digestive system and out the other end (or sometimes through two digestive systems). The authors suspected that reports of goats dispersing argan seeds by this more common mechanism were mistaken, because goats do not usually poop large seeds.

The researchers have witnessed sheep, captive red deer, and fallow deer spitting seeds while chewing their cud, and suspect this spitting variation on endozoochory may actually be common — and perhaps an essential route of seed spread for some plant species.

Source:Science Daily

{Despite differences, mountain and savannah honey bees in East Africa are same sub-species}

Mountain-dwelling East African honey bees have distinct genetic variations compared to their savannah relatives that likely help them to survive at high altitudes, report Martin Hasselmann of the University of Hohenheim, Germany, Matthew Webster of Uppsala University, Sweden, and colleagues May 25th, 2017, in PLOS Genetics.

Honey bees living in the mountain forests of East Africa look and behave differently from bees inhabiting the surrounding lowland savannahs. Mountain bees are larger, darker and less aggressive than savannah bees, and can fly at lower temperatures and conserve honey when flowers aren’t blooming. To understand the genetic basis for these high-altitude adaptations, researchers sequenced the genomes of 39 bees from two highland and two lowland populations in Kenya. The genomes of all the populations are highly similar, but two regions located on chromosome 7 and 9 show consistent differences between bees living in high and low-altitude environments. The segment on chromosome 7 contains e.g. receptor genes for a neurotransmitter called octopamine, which plays a role in learning and foraging. The clear divergence of these two genetic variations suggests that they have an ancient origin and likely existed in bee populations before the groups spread their mountain and savannah habitats.

This comprehensive study of the genomes of high-altitude honey bees in Kenya reveals novel insights into their evolutionary history and the genetic basis of local adaptation. Scientists had thought that mountain and savannah populations were each distinct sub-species. The high degree of similarity in their genomes, as revealed in the current study, shows that they constantly interbreed. The highly diverged segments likely represent structural rearrangements, such as inversions, in which the exchange of genetic material is suppressed. Previous studies have identified octopamine as an important signaling molecule in other insects living in low temperature and low oxygen conditions.

Martin Hasselmann adds: “Our findings complement several other landmark studies (for example in Heliconius butterflies and Solenopsis ants) where adaptations have been similarly tied to structural variants or supergenes. However, this phenomenon has never been documented in honey bees before. Our results should therefore spur further research into the role of supergenes in environmental adaptation. We are planning now to measure the distribution of these divergent segments in other geographic locations and to elucidate the functional link of these genes with behavior.”

Source:Science Daily