Category Environment

According to a study, at the current rate of warming, the area of ice-free land in the Antarctic peninsula, in the west, is set to rise by 300% in the next century. That means invasive species will have more land and more water (thanks to melting ice) species of fly will face-off against invaders. The exact effect is difficult to predict precisely, say scientists.

Antarctica is home to species that can gather in greater densities than those in temperate or tropical climates, said Convey, pointing to microscopic arthropods known as Collembola, a million of which can squeeze into a square meter.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

 

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• Specimens of non-native species of flies, spiders, caterpillars, butterflies, wasps, beetles, moths, slugs, bugs, ants, moss and grass have been found in Antarctica over the years. Ground beetles, in particular, have been extremely invasive, preying on native insects.
• In a study, scientists found that foreign plants such as annual bluegrass, chickweed and yellow bog sedge, were establishing themselves in Antarctica. They found that seeds and other detachable plant structures were stuck to cold-weather gear that travellers and researchers brought to the continent. Disturbingly, 49% to 61% of foreign plants that reach Antarctica are cold-adapted and can withstand and colonise in extreme conditions.
• Scientists with the British Antarctic Survey have discovered that a species of fly originally from South Georgia – the chironomid midge, has flourished since its accidental introduction to Signy Island in the Antarctic in the 1960s. It has expanded to more than 650 feet away from its original site, and in some areas is more numerous than any of the native insects. The fly likely travelled unnoticed on the plants brought to Antarctica for research. In the 1990s and early 2000s, its population started to explode.
• Some species do manage to arrive by other natural means. But it is humans who bring in 99% of invasive species, say scientists.
• Transport of invasive species can be minimized by careful cleaning and checking of clothing, footwear, construction materials, food, equipment and vehicles sent to Antarctica.

 

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Invasive species cause harm to the ecosystem in many ways:

• In the absence of natural predators, a new and aggressive species can breed, spread quickly and overrun the local habitat. Native species may not have evolved defences against the invader, further boosting the invaders’ growth.
• The threats from an invasive species also include preying on native species and outcompeting them for resources, thereby restricting the growth of native species.
• Some invasive species are capable of changing the conditions in an ecosystem, such as the soil chemistry.
• Invasive species can change the food web in an ecosystem by destroying native food sources.
• People who depend on the ecosystem’s native resources will also be affected.

 

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• Some species arrive in a new area through migration.
• Some are spread unintentionally by human activities. When people travel, they often inadvertently carry alien species along. For instance, insects may arrive in a new place by travelling on luggages.
• Some species are introduced on purpose as pets or to combat pests, which turn out to be invasive in the new place.
• Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes, and crates that are shipped around the world.
• Some ornamental plants can escape into the wild and become invasive.
• Illegal smuggling/trading of fruits and vegetables across borders can introduce not only potentially harmful new plant species but also any insects and parasites that may live in them.
• Higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loose strife—to move into new areas. 

 

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Invasive species are organisms that migrate to or are introduced to a new geographical location, where they pose a threat to the environment. They could be insects, plants, animals or pathogens. These species start to grow and multiply quickly in the absence of natural predators from their original homes.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.  The impacts of invasive species on our natural ecosystems and economy cost billions of dollars each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems. They can harm the environment, the economy, or even human health. Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label “invasive.”

 

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If you removed everything from your home that contained plastic, how much would be left? Many kitchens would be almost bare. Most carpets and rugs would go, many clothes and perhaps the curtains would vanish. There would certainly be no telephone, hi-fi or television.

And think of all the other things made of plastic, such as riot shields, credit cards, artificial snow and hip joints. Now Australians are even buying their plastic goods with plastic banknotes.

The term ‘plastics’ covers a wide range of materials man-made from two basic ingredients: carbon and hydrogen. By adding extra chemicals, plastics can be given special properties like extra strength, heat-resistance, slipperiness and flexibility.

There is almost no end to the number of plastics that can be created by combining chemicals in different ratios and patterns. Scientists are already trying to develop a plastic as tough as steel, as clear and waterproof as glass and as cheap as paper.

Plastics are made up of large molecules called polymers, which are formed by smaller molecules joining together in long chains. These chains become tangled, giving plastic its strength – considerable force is needed to pull the chains apart.

When most plastics – called thermoplastics – are heated to about 3900ºF (2000ºC) the chains stay intact but move apart enough to slide over one another. This allows thermoplastics to be repeatedly heated and moulded into new shapes. Once the plastic has cooled it holds its neew shape and maintains its strength.

However, there are other plastics which, once moulded, remain hard and keep their shape even when reheard. These are thermosetting plastics.

The process of getting small molecules to join up and form larger ones, called polymerization , differs from one plastic to another. But it often involves high pressures and the use of special agents, called catalysts, to encourage the small molecules to link up.

The carbon and hydrogen atoms that form the base of all plastics come from crude oil. Oil consists of hydrocarbons – hydrogen and carbon molecules bonded together. Hydrocarbons range from simple molecules like methane (a gas made up of one hydrogen atom combined with four carbon atoms) to tars and asphalts, which may have hundreds of atoms.

In the process of refining crude oil many different hydrocarbons are produced, one of them is the gas ethane (two carbon and six hydrogen atoms) which can be converted to another gas, ethylene, and then polymerized to make polyethylene (polythene). Similarly, propane gas becomes polypropylene. These two plastics are used to make bottles, pipes and plastic bags.

PVC – polyvinyl chloride – is chemically similar to polythene, but its hydrogen atom is replaced by a chlorine atom. This slight change makes PVC ‘flame retardant’, making it safer to use in the home. If four fluorine atoms are used rather than the chlorine atom, polytetrafluoroethylene, PTFE, is made. This, known as Teflon, is used for nonstick frying pans and bearings.

Many polymers have been made in the laboratory, but only those with the most useful qualities, like polystyrene, PTFE and nylon, are produced industrially.

 

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