Scientific newssheets
Page 1 : Results 1 to 5 on 27
336 - Decline in rainfall in the Amazon Basin
December 2009
Definition of climate variability and long-term trends in tropical regions is a major element for establishing scenarios for the future evolution of climate and ecosystems in these particularly fragile environments. The Amazon Basin is emblematic of this issue, owing to its key role in Earth’s climate and to its tropical rainforest, the most extensive in the world. IRD researchers and their partners 1 have conducted the first analysis of long-term climatic variations over five Amazon Basin countries (Brazil, Peru, Bolivia, Colombia and Ecuador). In 40 years, over the basin as a whole a clear decline in precipitation was found. There was an estimated relative decrease of 9% between 1975 and 2003. These studies yielded clues for a better understanding and prediction of variations in the climate upon which the “lung of the Earth” depends.
335 - Leishmaniasis: medicinal plants for a neglected disease
December 2009
Leishmaniasis is a frequent health problem for the Chayahuitas, as for other Amazonian communities, particularly in Bolivia, Peru, Ecuador and Colombia. WHO estimates that this disease, in its different forms 1, affects about 12 million people in the world, from America across to Asia, by way of Europe and Africa. Yet it is still a neglected disease 2. The main treatments currently available carry a certain toxicity and require hospital follow-up care. Such services are rare in the endemic areas where indigenous peoples such as the Chayahuitas live.
The Chayahuitas successfully use local medicinal plants as treatments. Aiming to detect the most effective therapeutic agents and explore new ways of controlling leishmaniasis, IRD researchers and their partners 3 studied the Chayahuitas’ perception of the disease, then recorded and analysed their healing practices. They found some active plants which could eventually be incorporated in treatment programmes.
334 – Wallis and Futuna: when Earth and sea go wild
December 2009
In the middle of the night of 29 to 30 September 2009, tremors shook the Earth to the North of the Tonga Islands in the South Pacific. This was a strong submarine earthquake, with a magnitude of 8 on the Richter (1) scale, and it triggered a tsunami, a giant wave which devastated the islands of Tonga and Samoa. In the early hours of 30 September, the wave crashed on to the coasts of Futuna (2), 600 km from the earthquake epicentre. Its force when it hit these islands was the greatest ever previously recorded. An IRD scientist and his research partners (3) measured the impact of this event on the archipelago.
Futuna is located on the circum-Pacific seismic belt, which corresponds to the line of subduction of the various oceanic tectonic plates of the Pacific beneath the Australian, Eurasian and American plates. Futuna lives under the shadow of a strong tsunami hazard. The research should yield an assessment of the danger and lead in the long term to ways of reducing the vulnerability of the archipelago’s inhabitants, who are in severe danger owing to their way of life strongly dependent on marine and coastal activities.
333 – Biodiversity models in question
November 2009
Many species manage to coexist in the same ecosystem. How do they do this and share the available resources? Since Darwin and his species theory 150 years ago, ecologists have been seeking to determine the factors favouring diversity in nature. In almost a century of research, the most strongly supported hypothesis has been the niche theory. This model postulates that a species occupies an ecological niche( 1)
of its own, to which it is well adapted. However, a second hypothesis, the neutral theory, with diametrically opposing principles, has come to the fore since the early 2000s. According to this the various species in the ecosystem have equivalent roles.
A population study on marine phytoplankton( 2), led IRD researchers and their partners( 3) to call this dichotomy into question. They put forward a new intermediary model, combining the two main theories, to explain biodiversity and, in the long term, help preserve it.
332 - African women reacting against Aids
November 2009
Over 33 million people in the world are living with HIV, the Aids virus, and 75% of them live in Sub-Saharan Africa. Most of the people ill with the disease on that continent are women. In the Ivory Coast, the West African country most affected by the pandemic, two women are contaminated for every one man. Women are indeed physiologically more vulnerable to a sexually transmitted infection like HIV.
However, in spite of this gender inequality in relation to Aids, far more women than men are taking part in treatment programmes. Is it their concern to protect their children and see them grow up? Are programmes better geared to women? IRD researchers and their partners (1) recently found evidence for a “gender paradox” and are seeking to understand this by examining women’s experience with HIV care measures.
