T.v. Padma, Author at ��è��Ƶ

India’s drought foretells of greater struggles as climate warms

T.v. Padma — Wed, 18 May 2016 16:00:23 +0000

All is not well with India’s water supply

Indranil Mukherjee/AFP/Getty Images

India is in the grip of a severe drought as a result of two successive weak monsoons and a searing heatwave. Its reservoirs dipped to less than a fifth of their total capacity in May, and are estimated to be affected in some way.

Reports of parched, cracked soils, and desperate migration from Marathwada in the west of the country – one of the worst-hit regions – are at odds with the country’s image as an emerging economic and technological power, aspiring towards .

The hope is that this year’s monsoon, due to arrive in the first week of June, will turn things around. But many see the drought as a wake-up call for India, and a sign of things to come for the region as global warming takes hold.

India’s economy still depends largely on monsoon rains, with two-thirds of its agricultural land fed by rain. Other parts of the country are but this is , leading to and declining water tables.

The droughts of the 1980s and 1990s were those of poor India, says Sunita Narain, director general of the Centre for Science and Environment in Delhi. “The 2016 drought is of a richer, water-guzzling India.”

An analysis carried out for the World Bank in 2013 found that . If global average temperatures rise by 2��^oC, it predicts that unprecedented spells of hot weather will occur far more frequently and cover much larger areas. The monsoon will become highly unpredictable and droughts are expected to be more frequent. “Crop yields are expected to fall significantly because of extreme heat by the 2040s,” it says.

Not so drought-proof

India’s attempts to get its agriculture into a state where drought has no negative impact on the economy – are, at best, patchy. In 2013, the country signed up to . The aim was to develop strategies for drought mitigation and management.

India has schemes for drought-hit farmers but there has been little take-up as many are too poor to pay the premium, and even if they do, the process required to verify crop losses can be too cumbersome to complete. Similarly, rainwater harvesting schemes are neglected despite policies to make them mandatory.

And while experts recommend that the government should encourage farmers to grow crops that need little water such as hardy millets, water-guzzling crops like sugarcane to keep the politically powerful sugar barons on side.

There have been no serious attempts to utilise local crop diversity, conserve water or recharge depleted aquifers, says Rajeswari Raina at the National Institute for Science, Technology and Development Studies in New Delhi. “There is just no political will to move away from an [intensive irrigation-driven] agriculture system.”

Like its people, the Indian government, which has been , is praying that this year’s monsoon will set things right. The rains are .��But this won’t give impoverished farmers the money they need to buy seeds or livestock, and it may not do much for the water table – if the soils are so damaged that their ability to absorb the heavy rains is hampered.

Either way, if a rising economic power like India can’t manage its crops and water, it doesn’t bode well for the region in a future, warmer world.

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Russian doll disease is a virus inside a parasite inside a fly

T.v. Padma — Mon, 10 Aug 2015 13:15:00 +0000

Red blood cell, complete with Leishmania parasite (Image: Eye of Science/SPL) It’s a Russian doll of a tropical disease. Leishmaniasis, a disease that infects 12 million people worldwide, is passed to humans by sandflies infected with the Leishmania parasite. Now it seems that in some species of the parasite, a virus hiding inside is silently helping it subvert treatment. Leishmaniasis is a common problem in Latin America, South Asia and parts of Africa. Depending on the form the disease takes and the species of parasite, it either attacks the skin, mucous linings of the nose and mouth, or the internal organs. It’s not easy to treat. “Treatment failure is a major challenge for doctors and researchers, says Jean-Claude Dujardin from the Institute of Tropical Medicine in Antwerp, Belgium. Depending on the drug and the region, treatment failure rates vary, says Dujardin. In Latin America, for example, two out of five people relapse after treatment, but this can rise to 70 per cent in parts of South Asia where another species of Leishmania circulates. The most obvious explanation is that the parasite has become resistant or that people aren’t taking the drugs properly.

Infected parasite

But in Latin America at least, it looks like there’s an alternative explanation. . It now seems the same applies in people. “The parasite is already infected by the virus and it is this package that gets transferred to the sandfly,” says Dujardin, part of an international collaboration that hunted down the virus in people infected with the L. braziliensis parasite in the Amazon basin of Bolivia and Peru. Of the people whose parasites were infected with the virus, 53 per cent of them had relapsed after drug treatment. Only 24 per cent of the people whose parasites were virus-free did so. Similar results were seen in people infected with L. guyanensis, another parasite species common in the area. There was no link between treatment success and the parasite’s resistance to the drugs the patient was given. “You need to imagine the system like a Russian doll,” says Dujardin. The parasite multiplies within the human host cell, and then the virus lurking within it wakes up and begins interacting with the host cell, he says. “Leishmania alone, without the virus, is already known to subvert the immune response; it seems that the virus adds another layer of subversion, leading to treatment failure,” says Dujardin.

In good company

In some ways it’s not surprising that a virus can infect a parasite. It’s often said that parasitism is the most common way of life – with more than half of all animal species on the planet living off another in some way. But Kevin Lafferty, an ecologist at the University of California, Santa Barbara, says that although viruses are known to infect bacteria and parasites, instances of a virus infecting a parasite that in turn infects another host are not very common. “This is a fascinating piece of detective work with important implications for human health.” However, Jorge Alvar at the Drugs for Neglected Diseases Initiative in Switzerland, cautions that we still don’t how the virus affects the evolution of the parasite, or how it ultimately impacts the patient. But, in theory, the virus gives us an added drug target, he says. “In this case a patient could be treated with either anti-Leishmania drugs or anti-virals, or both. Similar viruses have been found in other parasites, for example, in the diarrhoea-causing Giardia and Cryptosporidium, and in Trichomonas vaginalis that causes a sexually transmitted infection. Surveys of their prevalence could help us better understand the effect of viral infection of parasites and could play a role in how we treat these parasitic diseases, says Dujardin.

Journal reference: Journal of Infectious Diseases, DOI: (L. braziliensis); DOI: (L. guyanensis)

Multitalented giant clams keep corals reefs healthy

T.v. Padma — Thu, 18 Dec 2014 11:45:00 +0000

Beautiful and talented

(Image: Alex Mustard/naturepl.com)

It’s time they came out of their shells. It seems the world’s largest molluscs, the giant clams of the Indo-Pacific coral reefs, have been doing a huge amount of good work we knew little about.

These sea creatures turn out to be multitasking ecosystem engineers. They are reef builders and shapers, food factories, shelters, reservoirs of algae, and water filters, all rolled in one.

Giant clams have been around coral reefs since about 38��million years, the largest of them growing to 1.2��metres long and weighing more than 200��kilograms.

But, their role in the ecosystem is poorly understood, says , a marine ecologist at the National University of Singapore.

Todd and his colleagues have examined the clams’ roles, and hope the findings will reinforce the case for conserving the molluscs. Giant clams are under great pressure from threats such as overfishing and global warming.

The team found that the 13 species of giant clams are food factories for coral reef inhabitants. They host food-making algae known as zooxanthellae, serve as food for predatory crabs, lobsters, and even their spawn and faeces attract opportunistic feeders and scavengers such as small snails, crabs and lobsters.

A place to hide

Giant clams are also nurseries for fish, serving as refuges for juveniles escaping predators, and the shell ridges provide privacy for adults laying eggs.

Their shells also help build reefs. Dense populations of clams mean that some species produce 80 tonnes of carbonate shell material per hectare each year, which is available as housing for soft corals, sponges, sea squirts and large algae.

But these benefits are likely to continue only if giant clam populations are healthy, making their conservation paramount, the team concludes.

“There is a pan-global decline in clams,” says , a marine ecologist at the Bombay Natural History Society, who is running an Indian government-backed programme on clam conservation.

“They are a vital indicator species of coral reef health and their ecological contributions are innumerable,” he says. Once gone, restoring giant clams will be a great challenge because the highly specialised niches in which they occur are continuously deteriorating, he adds.

And in India, he says, there are other challenges.

“Our emphasis on megafauna in India makes looking at lesser known species almost impossible,” he says. “Even within megafauna, Indian conservation approach is almost entirely terrestrial and is too tiger-centric. The study puts forward the case for conservation of these lesser-known species.”

Journal reference:

T.v. Padma, Author at ��è����Ƶ