Architects of wild waters
QUESTION Has any country successfully reintroduced beavers to the wild?
Long prized for its fur and castoreum (a scent extract used in perfumes and as a food additive), the Eurasian beaver (Castor fiber) was almost hunted to extinction by the mid-19th century.
Fewer than 15,000 remained, with small numbers in Belarus, Mongolia, Russia, Ukraine, China, France, germany and norway.
Since the 1970s, the Eurasian beaver has been successfully reintroduced to much of its former range.
While Finland and Russia did this to support a commercial fur trade, the releases in Austria, Romania, Denmark, Spain and Scotland have been for conservation reasons.
Beavers are one of the only animals that can engineer their environment. They coppice and fell trees, creating open areas for new growth and increasing canopy diversity.
They also dam water systems to create wetlands, resulting in an improved habitat that benefits plants, animals, amphibians and insects.
The best indication of the beaver’s ability to recolonise comes from Sweden, where the reintroduction programme is the most advanced.
The beaver was declared extinct in Sweden in 1871. By 1940, 80 had been reintroduced. Since then the population has exploded and there are thought to be more than 150,000.
This success is seen as a boon to the tourist industry. However, the animals’ preference for broad-leaved trees, such as aspen, has brought them into conflict with foresters, and they can be hunted in Sweden with a licence.
Beavers have been present in the capital, Stockholm, since 1997. This city of canals and islands makes an ideal habitat for the aquatic mammals.
Though beloved by Stockholmers, they have been known to fell trees and even bite people, resulting in isolated, small-scale culls.
John Devereax, Harwich, Essex.
QUESTION Is there an absolute maximum temperature?
ABSoLUTE zero — that’s zero Kelvin, or minus 273.15c — is the coldest anything can be. It’s the temperature threshold at which atoms lose their kinetic energy and stop moving.
In contrast, there’s no agreed upon value among physicists for a maximum possible temperature.
A current best guess is the so-called Planck temperature, named after the german physicist Max Planck. It equals 100 million million million million million degrees, or 10^32 Kelvin.
In the standard model of particle physics, which explains electromagnetic, weak and strong interactions (but not gravity), the hottest possible temperature occurred a fraction of a second after the Big Bang.
During that minuscule period of time, the emitted light had a wavelength of only 10^-35 metres.
This is called the Planck length and is the smallest measurable distance in the universe. Due to this small wavelength, the temperature was ‘absolute hot’.
Physicists hypothesise that at any temperature higher than the Planck standard, the gravitational forces of the affected particles would become so strong that they could create a black hole. However, this maximum hot is not universally agreed upon. String theorists, who believe the universe consists not of particles, but of tiny, vibrating strings, suggest absolute hot is two orders of magnitude lower, 10^30 Kelvin.
QUESTION Is there any truth in the legend that the Sargasso Sea was the graveyard of abandoned ships?
THE Sargasso Sea is a vast area of ocean named for a genus of free-floating seaweed called Sargassum.
It is unique in having no land boundary, but is defined by a gently clockwiserotating lens of warm water, its location determined by four currents forming this ocean gyre.
The Sargassum are holopelagic — the algae not only floats freely around the ocean, but reproduces vegetatively on the high seas. other seaweeds reproduce and begin life on the ocean floor.
Portuguese sailors gave the sea its name because the air bladders on the floating seaweed reminded them of small grapes, which they knew as salgazo.
Christopher Columbus noticed the plant life in 1492 — ‘such an abundance of weeds that the ocean seemed to be covered with them’.
The area was known as ‘the doldrums’ because of its stillness relative to the powerful currents surrounding it.
Small wonder that sailors trapped within the mass of seaweed feared their ships would become irretrievably entangled, or that strange creatures lurked beneath the surface. However, the seaweed is not obstructive to ships.
Author William Hope Hodgson added to the myth with his Sargasso Sea stories in the early 1900s. In his fiction, a graveyard of ships have become marooned within the choking seaweed and are prey to huge monsters.
The Sargasso Sea was once considered to be a biological desert, but marine biologists have uncovered an intricate web of life.
Turtles use Sargassum mats as nurseries where hatchlings have food and shelter. It also provides a habitat for shrimp, crab, fish and other marine species that have adapted to this floating algae.
Andrew Talbot, Southampton.
IS THERE a question to which you want to know the answer? Or do you know the answer to a question here? Write to: Charles Legge, Answers To Correspondents, Daily Mail, 2 Derry Street, London W8 5TT; or email charles.legge@dailymail.co.uk. A selection is published, but we’re unable to enter into individual correspondence.