Archive for August, 2008

Aug

27

2008
 
 

Take a deep breath



Scientists discover cause of high bat mortality near wind turbines

quixoticismBats suffer much higher mortality near wind turbines than birds, yet quite why the echolocating mammals should fall foul to such a large solid object as a whirring rotor has mystified scientists. In a paper published this week in Current Biology, University of Calgary researcher Erin Baerwald and colleagues provide evidence that it’s not direct collisions that cause many of the fatalities, but the sudden change in air pressure as the blade sweeps through its deathly arc. The bat’s tiny lungs effectively explode: Baerwald’s study found that although around half of dead bats examined had no external evidence of injury, some ninety percent had internal damage consistent with “barotrauma”. Migrating bats are particularly prone, so one way to lessen the carnage would be to switch the turbines off on all but the windiest nights. Source: Baerwald EF, D’Amours GH, KlugBJ & Barclay RMR (2008) Barotrauma is a significant cause of bat fatalities at wind turbines. Current Biology DOI: TBA

Image: © Brian Jackson

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Aug

7

2008
 
 

The ice-mollusc cometh



Pacific shellfish set to resume ancient Atlantic invasion as Arctic ice melts

Flying snails make good invadersWhen the Arctic ice finally melts away, by around 2050, a gang of North Pacific shellfish are going to finish something they started three and a half million years ago. Writing this week in Science, UC Davis geologist Geerat Vermeij and collaborator Peter Roopnarine argue that at least 56 molluscan lineages have the potential to expand their ranges across the Bering Strait into the North Atlantic. The fossil record shows that such an invasion was interrupted with the widespread establishment of permanent sea ice, a barrier we humans have successfully broken down over the last couple of hundred years. The authors urge us to “anticipate with interest” the molluscan army’s progress. That’s one way to look at a melting icecap… Source: Vermeij GJ & Roopnarine PD (2008) The coming Arctic invasion. Science DOI: 10.1126/science.1160852

Image: © Russ Hopcroft | NOAA

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Aug

6

2008
 
 

Bone dry



Not all elephant calves are equal when drought bites hardest

Elephant familyMale elephant Loxodonta africana calves with young mothers are most likely to die during a drought, according to findings published this week in Biology Letters. The study, led by Wildlife Conservation Society researcher Charles Foley, used data from the 1993 extreme drought in Tarangire National Park, Tanzania, to look for patterns in calf survival resulting from calf sex, mother’s age and family group. Some family groups migrated out of the Park during the drought: only these clans contained individuals old enough to remember the previous severe drought of 1958-61. Seems that an elephant really does never forget. Source: Foley C, Pettorelli N & Foley L (2008) Severe drought and calf survival in elephants. Biology Letters DOI: 10.1098/rsbl.2008.0370

Image: © Charles Foley

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Aug

4

2008
 
 

Soft boiled eggs



Reef-building animals will struggle to reproduce as the climate changes

purple sea urchinsOcean acidification – the result of elevated atmospheric carbon dioxide levels – will affect the sex lives of many marine organisms, according to a study published recently in Current Biology. Jon Havenhand, a marine biologist at the University of Gothenberg, and colleagues found that the swimming ability of sea urchin Heliocidaris erythrogramma sperm, fertilization rate and subsequent development of embryos are all negatively affected by relatively modest changes in the water acidity. Acidification causes many problems for calcifying organisms and the future looks gloomy for coral reefs. The new findings add to their woes, as direct effects on reproduction had previously not been investigated. One can only hope that the invisible hand of selection will guide these marine creatures to a state of adaptation that copes with the conditions they will have to face. Source: Havenhand JN, Buttler F-R, Thorndyke MC & Williamson JE (2008) Near-future levels of ocean acidification reduce fertilization success in a sea urchin. Current Biology DOI: tba

Image: © Tammy Peluso

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Aug

1

2008
 
 

What do krill kill?



Using molecular techniques to understand krill diet

put another krill on the barbieComplex food webs could become easier to analyze with the advent of molecular techniques to identify the remains of prey items from part-digested stomach contents. However, a major stumbling block has been spotting the DNA of rare prey items against a background overwhelmed by the predator’s own DNA. Writing in Frontiers in Zoology, Hege Vestheim and Simon Jarman – biologists at the University of Oslo and the Australian Antarctic Division, respectively – describe a new method to block predator DNA from the identification process. As a result, their tests on Antarctic krill Euphausia superba were able to identify, for the first time, what one of the most abundant animals in the world eats to survive the winter. The method must assume krill don’t resort to cannibalism to make it through the toughest half of the year, but otherwise presents a neat way to find out what an animal has eaten: the study even, er, threw up several unknown species of algae. Source: Vestheim H & Jarman SN (2008) Blocking primers to enhance PCR amplification of rare sequences in mixed samples – a case study on prey DNA in Antarctic krill stomachs. Frontiers in Zoology DOI: 10.1186/1742-9994-5-12

Image: © NOAA

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