One third of fish stocks to keep the birds - a new law in ecology
American scientists on the basis of analysis of global databases brought new environmental regulations. It reads as follows: one third of stocks leaving seabirds. This means that maintaining the stability of seabird populations requires that they got it to feed at least one-third of the maximum stock of their prey. Fisheries often exploit the same fish populations, which serve as food for birds, so the new rule should be considered when assessing the allowable catch. But more importantly, that the stability threshold of bird populations was the same for all regions and all species of birds that scientists have to study. This means that open a new fundamental law, it is based on as yet unknown relationship of ecology and demography.
A new study by American ecologists from Scientific Institute, Carnegie Institute of Medicine of Howard Hughes, National Institute on Aging and Johns Hopkins University, deals specifically with this subject: how much to pay (or leave) the birds feed to their chicks were not hungry in the empty nest. It is true that specific topic is narrower - it is a marine bird and fish feed. In this context, subjects marked a song, it becomes very relevant: the man is competing with sea birds, are both concerned consumers of fish stocks. In this competition for the extraction of man is clearly in a better position, and the birds have to wait for an appropriate solution twopenny.
Usually, the problem of research on assessment and determination of the maximum catch quotas are set in terms of conservation of fisheries resources, that is, how much can be caught, so reserves are the most important food items remained stable, with steady replenishment. A new study raises the question of non-traditional way: how many fish can be caught to have remained stable populations of sea birds. A very worthy question posed by a successful predator-competitor. And this question was worthy of a result very surprising and interesting solution. Birds - by anyone, anywhere in the world - to leave no less than a third of their maximum stock of food items. If year after year, leaving smaller, the breeding success of birds will drop dramatically and their numbers are gradually reduced to a minimum. This is how scientists have received this response.
They collected data on 14 species of birds that live in different parts of the world. These data represented a time series of parallel population dynamics of birds and their chicks and food items relevant populations. By the way, then it should be noted that in addition to conventional forage fish - herring, capelin, pollock, sand lance, anchovy, sardine - and take into account the biomass of krill, which is the main prey of Antarctic birds - penguins, gulls and red-. Naturally, the number of indicators of both were used not as absolute values ??and in a normalized form. Otherwise, it would be difficult to compare the different scales and different quality data for different species and ecosystems. Normalized numbers and biomass in the simplest way - as a number of standard deviations from the mean (and we certainly have not forgotten that the 99 percent confidence interval is placed around the Six Sigma). So it is possible to construct a data series for all uniform dependence of podroschennyh chicks (success rate of reproduction) of the biomass or the number of food items.
All of the new function, as clearly seen from the graphs that have a characteristic feature. Approximately in the mean values ??of the x-axis function is obvious inflection. If the abundance of food is above average, the breeding success of birds are not too dependent on this index and rapidly to an asymptote, but if the lower - that breeding success is significantly reduced. Birds are very sensitive to lack of food. And this trait is observed for all species and all marine areas, whether Antarctica or the North Sea, we take for comparison the penguin is accustomed to krill or skua prefer gerbils. Everywhere, just only the abundance of food was below average, the birds are not able to grow enough chicks. Properly conducted statistical analysis showed that the inflection point on the graphs in the range [-0.3 + 0.13] Sigma, which ranges from 31 to 39% of the maximum recorded values ??of biomass or abundance of food. The scatter of values ??between ecosystems was only 28%, environmentalists are more common with much greater scatter of values.
So, we have a clear rule of thumb is to maintain stability in the populations of sea birds they need to keep at least one third of the maximum stock of fish within their diet. This rule makes us think and practitioners and theorists. For practitioners it is - another factor that must be considered when assessing the catch quota. Here it will have to somehow agree with the economists in the field of nature protection. The former will be an additional source of care, and at last - a good argument prohibitive.
But much more food for thought were environmental theorists. Why a threshold of one third of the stock was so stable, so ubiquitous? Biology of birds are different, the characteristics of populations and population dynamics are different, the device ecosystem, with all their internal links nothing to do with each other are not ... It seems to be and at what point, after which the birds start to feel a lack of food, should be everywhere her. But no, despite all their differences, he was more or less similar. What's the matter?
The answer is probably to be found in some of the fundamental laws of formation and demographic characteristics of the ecosystem and their interrelationships. I see here a wonderful perspective that will help bring the controversial current environment to a new level of understanding.
Tiny hot extrasolar planets may be the remains of the gas giants
Astronomers from the University of Toulouse figured a couple of exoplanets, one of which has the potential to become the smallest of the currently open. Planets orbiting a red dwarf the former at a distance of only 0.9 and 1.1 million kilometers, can not have an atmosphere, which means that their daily hemisphere is heated to about 8-9 thousand degrees (half a hot surface of the Sun).
On the eve of Christmas and New Year, astronomers have presented a very pleasant surprise. December 20 NASA at a specially convened press conference heralded a highly unusual planetary system discovered by the Space Telescope "Kepler." It consists of two rocky planets of terrestrial size and scale of the three planets of Neptune. These planets are treated close to each other in the vicinity of the yellow dwarf sun-like Kepler-20, remote from us at 950 light-years. Both zemlepodobnyh body Kepler-20e and Kepler-20f, whose radii are equal, respectively, 0.87 and 1.03 of the radius of the Earth, and the masses do not exceed two or three Earth masses, were immediately declared the most miniature of extrasolar planets discovered to date.
However, this record lasted only one day. December 21st international team of astronomers led by Stefan Sharpine (Stephane Charpinet) from the Institute of Astrophysics and planetologicheskih Studies at the University of Toulouse, said in a recent issue of Nature, in 2011 another pair of extrasolar planets, one of which has a good chance to claim first place in the list naimelchayshih . True, they have found a different way than the world of Kepler-20, so their size is not measured, but estimated on the basis of model calculations.
Life Path of newly discovered extrasolar planets are much more tragic fate of all other known exoplanet science - and that says a lot. 18 million years ago, they emerged from the furnace of fire, flames of hell which evaporates completely their gas shells, but was unable to burn until the end of the nucleus, consisting of refractory species.
If the reader is sufficiently intrigued, you can go to the details. The new discovery was again done with the "Kepler", which this time did not work in his main quality. It was launched primarily for the search for exoplanets, which are partly overshadowed for terrestrial observers, their stars and to issue its own presence. This telescope with an aperture of 95 centimeters has a highly sensitive photometer on the forty-two 2.2-megapixel photosensitive semiconductor matrices. Photometer traces the stellar brightness oscillations, suggesting the presence of a star of one or more of nonluminous satellites. However, the same device can be used for a detailed study of variable stars, which are also regularly change their brightness. By virtue of their space, "registration" it makes it much better than terrestrial equipment.
A unique research potential "Kepler" has decided to use the international group astroseismology, formed shortly before its launch. It has formed a consortium of scientific Astroseysmichesky "Kepler» (Kepler Asteroseismic Science Consortium, KASC) with the center in Denmark, Aarhus University. Its members have time to monitor several variable stars in our galaxy. Among them was a single star KIC 05807616 (also known as the index of KPD 1943 4058), located at the junction of the constellations Cygnus and Lyra in 3900 light years from the Sun. Its spectra are interested scholars long before launch, "Kepler" in March 2009. It belongs to the family of hot subdwarfs of spectral type B (sdB stars), lying on the extreme horizontal branch Hertzsprung-Russell. The luminosity of these stars is provided by thermonuclear burning of helium, from which they are composed almost entirely, and (the proportion of hydrogen there is less than one percent).
Most often, hot subdwarfs are remnants of the red giant - not too heavy (no more than two solar masses) of main sequence stars, have exhausted their hydrogen fuel and a hundred-fold increase in its size due to internal instability. Usually a red giant remains bloated hydrogen atmosphere for one to two billion years - as long as its central region is not compressed to a temperature to ensure fusion of helium burning. However, it can lose a hydrogen atmosphere before the start of helium burning core, which leads to the birth of a hot subdwarf. The reasons for such relief is not yet entirely clear, but it probably makes the presence of the companion star, which attracts the gas of the outer shell of a red giant and the gravity weakens the ties that bind him to the nucleus. Strip the core continues to burn helium until its conversion to oxygen and carbon. After that thermonuclear burning stops, since the mass subdwarf is insufficient to continue the fusion. He becomes a low-mass white dwarf and then does not change.
The surface temperatures of the Class B subdwarfs lie in the range of 20-40 thousand degrees. They change as a result of intense brilliance fluctuations caused is believed to be deep-acoustic oscillations. Pulsation periods range from two minutes to three hours. For this reason, these stars are of great interest to astroseismology.
The previous study KIC 05807616 showed that the star has become subdwarfs 18 million years ago and that her current weight is equal to nearly half the mass of the Sun at a radius of only one-fifth of its radius (so that the substance of this star is 60 times denser than the sun). Subsequently became the subject of KIC 05807616 six-month observation, "Kepler" and as such has received a new index KOI 55 (abbreviation means Kepler Object of Interest). The result revealed a lot of brightness fluctuations with periods of anywhere from half to two and a half hours, and amplitudes up to 0.15% of the average brightness of the star. At the same time Stephen Sharpine and his colleagues found two more series of extremely weak (with the amplitudes of the order of thousandths of one percent) of the oscillations with periods of stellar luminosity 5.7625 8.2293 hours and hours. Since the theory is that no internal processes can not produce long-period oscillations of brightness as a hot subdwarf, scientists have assumed that it has two satellites, which are periodically shield the tiny fraction of its radiation. If such moons do exist, they must go around the star at very small distances - only 0.9 and 1.1 million kilometers, which is much less than one-hundredth of an astronomical unit.
This hypothesis leads to very important consequences. In recent years, astronomers have found some giant gas planets orbiting subdwarfs B-Class, but they are distant from their stars more than a tenth of an astronomical unit. Candidates for new planets and KOI 55.01 KOI 55.02 not only can not be gas giants, but generally not in a position to have any atmosphere, since in such proximity to such a hot star can not survive, no gas shell. Due to the proximity of the same tidal forces of each planet is tilted toward the star by one party only (just as focused on the Moon relative to Earth). It follows that their daytime hemisphere is heated to about 8-9 thousand degrees, and therefore half as hot surface of the sun.
Where do these fiery monsters? The authors of the article in Nature see them as the possible remains of the gas giants, once orbiting a normal main-sequence star, which was the predecessor of subdwarf KIC 05,807,616. When she became a red giant, the two planets were in its atmosphere, where they were staying an unspecified number of years (at least several tens of millions). During this time they have completely lost their gas, saving only solid rocky core, or rather parts of them. They are also much closer to the nucleus due to loss of red giant orbital velocity due to the deceleration in its atmosphere. When the aforesaid giant dropped the outer layers and become a subdwarf, both bodies have ceased to lose kinetic energy and stabilized at their current orbits. There they remain, as will become subdwarf white dwarf and for trillions of years to cool to ambient space. Naturally, the same will happen with the two planets.
This hypothetical, but plausible, scenario is an interesting sequel. As I said, subdwarf KIC 05807616 is likely not part of the binary system (in any case, this data shows that while all the telescopic observations). The question is, what then is called the "slimming" of its giant parent? Stephen Sharpine and his co-authors do not exclude that in the absence of a companion star of the blame should be assigned to the planets themselves. We can assume that their gravity is so incensed the atmosphere of the red giant that she dissipated in space. This could only happen if the planets were originally close to its upper limit, because only there would be enough of gravity for its radical destabilization. Confirmation of this hypothesis would be the first example of the influence of planets on the evolution of their parent stars, so far discussed only in theory.
As I mentioned, the article presents estimates of the mass and size of KOI 55.01 and KOI 55.02. For these calculations, the authors had to make certain assumptions about the albedo (reflectivity) of the planetary surface, angle of inclination of the orbital plane relative to the direction of the Earth and the degree of heat transfer from day to night hemispheres. As a result, they concluded that the radius of KOI 55.01 0.759 earth's radius and its mass is 0.440 Earth masses. KOI 55.02 are slightly larger: 0.867 earth's radius and 0.655 Earth mass. So KOI 55.01 and really can be the easiest for the current day of exoplanets.
In conclusion, we should note one more circumstance. In this paper we briefly discuss the alternative scenario of birth subdwarfs class B, not linking this process with the evolution of red giants. According to this model, they can also occur when two white dwarfs - not only the oxygen-carbon, and the lighter helium. In this case, the subdwarf at the initial stage of its existence can get dense gas disk, which eventually give rise to one or more planets. Sharpine and his colleagues in principle do not exclude such a possibility, but still believe that so near a hot star for 18 million years hardly had time to be formed Earth-like planets.
