Tag Archives: nature

Engineered robot interacts with live fish

A bioinspired robot has provided the first experimental evidence that live zebrafish can be influenced by engineered robots. Results published 8 June in IOP Publishing’s journal Bioinspiration and Biomimetics, provide a stepping stone on the path to using autonomous robots in an open environment to monitor and control fish behaviour.

In the future, water-based robots could potentially contribute to the protection of endangered animals and the control of pest species.

The robot, created by researchers from Polytechnic Institute of New York University and Instituto Superiore di Sanitá, Italy, was 15 centimetres long and spray-painted with the characteristic blue stripes of the zebrafish. The tail of the robot was mechanically controlled by the researchers to mimic the action of the zebrafish itself.

When placed in a 65 litre fish tank, the movements of the robot’s tail attracted both individual and shoals of zebrafish; the researchers believe that such capability was influenced by its bioinspired features which were optimised to increase attraction.

For example, the robot was given a rounder shape to mimic a fertile female, which is preferred by both male and female zebrafish, and its colour pattern — a magnified stripe width and saturated yellow pigment — emphasized distinctive biologically relevant features.

The robot was in a fixed position in the tank so that the tail movements could be controlled, recorded and, most importantly, associated with the behaviour of the zebrafish.

The fish tank where the experiments took place was divided into one large middle section and two smaller sections at either end, separated by transparent Plexiglas. A total of 16 experiments were performed in which individual, and then shoals of, zebrafish were placed in the middle compartment of the tank and two stimuli were placed at either end behind the Plexiglass.

The combinations of stimuli were: one fish versus an empty space; ten fish versus an empty space; ten fish versus one fish; the robot versus an empty space, and the robot versus one fish.

A camera was placed above the tank to monitor the movements of the zebrafish, and statistical tests were performed to calculate whether the robot acted as an attractive, neutral or aversive stimulus and whether this relationship depends on the fish being isolated or in a shoal.

Although the live zebrafish tended to prefer each other to the robot, when given the choice to spend time next to the robotic fish or an empty space, both the individual fish and shoal of fish preferred the robot. While the noise of the robot’s motor was shown to decrease its attraction, the actual beating of the tail emphasized its attractiveness.

The corresponding author, Dr Maurizio Porfiri, said: “These findings provide practical evidence that a species’ preference for conspecifics may be used to inspire the design of robots which can actively engage their source of inspiration.

“New studies are currently underway in our lab investigating the interactions between fish and robotic fish when they are free to swim together under controlled and ecologically complex conditions.”read more on :http://goo.gl/sauSO

Arctic’s wintry blanket can be warming.

Original Post By  Janet Raloff.

Arctic winters may be snowy and cold, but a deep blanket of snow can actually keep the soil surface fairly warm, a new study finds — at least in taiga, the conifer forests that may constitute almost half of the Arctic’s land cover.

Temperature plays a major role in determining not only plants’ uptake of climate-warming carbon, but also the soil’s potential for storing the element.

Scientists who develop computer programs to evaluate climate under changing conditions know this. Yet for convenience, their simulations have largely treated Arctic snows as if they blanket forest-free tundra, notes climate modeler Isabelle Gouttevin of the CNRS/University Joseph Fourier-Grenoble in France.

Her team has now quantified the impact of ignoring the taiga snows’ insulating capacity in climate simulations, and found that the oversight may make a substantial difference. At a depth of 50 centimeters, soil in wintry taiga can be 12 degrees Celsius warmer than computer simulations predict when all snow-covered Arctic terrain is treated like tundra, the researchers conclude June 2 in the Journal of Geophysical Research. Gouttevin’s team also finds that because forested soils heat up from a warmer baseline in spring, their summer temperature at 50 centimeters depth could be 4 degrees Celsius warmer than all-tundra simulations had assumed.

Blustery winter winds sweeping across the relatively flat tundra compact the snow’s crust, eventually diminishing the whole blanket’s insulating capacity. The taiga’s tree canopy protects the surface, allowing winter snows to remain fairly airy and insulating. This means some taiga soil surfaces can remain around the freezing point all winter, regardless of how low air temperatures plummet. Gouttevin’s team confirmed such details in late winter at tundra field sites in Alaska and taiga locations in Finland.

Accounting for taiga’s insulating snows decreases the amount of carbon that Arctic soils can hold by some 64 billion metric tons, the scientists estimate. Soil warming associated with taiga snows throughout the Arctic also could annually increase by 22 percent the activity of microbes that release carbon-based greenhouses gases into the atmosphere.

After accounting for the greater insulating effect of forest covered Arctic snow, “there is a slight shift in the carbon cycle,” Gouttevin says, “towards less carbon storage by vegetation. This was quite a surprise.”

Accounting for the higher insulating value of taiga snow leads to such a dramatic shift in soil warming, “that decomposition of soil organic matter (greenhouse gas production) and permafrost thawing would be significantly greater at the global scale,” says forest ecologist Glenn Juday of the University of Alaska Fairbanks. “What elevates this result from the mundane story of another [computer] model with another parameter that needs fixing,” he adds, “is the huge pool of carbon stored in cold or frozen soils in the north — more than the atmosphere and land plants combined.”