Web of Life

Several new species discovered by gifted Lankan naturalist

To most, a snail is something to gingerly pluck out from a plant pot and toss into the horizon. But to one young Sri Lankan scientist in England, these slimy, unassuming creatures offer the key to some of nature’s most pressing questions.

Twenty -eight-year-old Dinazarde Raheem has spent the last 11 years of her life investigating Sri Lanka’s land snails: Examining the animals in their home environments and making collections; studying and verifying available information; researching new species. Her work has helped reinforce what others have already, to an extent, established — that Sri Lanka has a high, even staggering, number of endemic snails.

The total number of species already known is approximately 250, with the greatest diversity found in the rainforests of south-western Sri Lanka. Of these, over 80 per cent are unique to Sri Lanka. And Dinazarde estimates that she may have discovered at least 50 more new species during the course of her fieldwork. These are soon to be formally described and catalogued. There may also be other new species in parts of the country that haven’t yet been surveyed.

Together with Fred Naggs — biodiversity and conservation officer at the Natural History Museum (NHM) in London, where Dinazarde is currently based — she has produced glossy colour guides of Sri Lanka’s snails in Sinhala, Tamil and English and is in the process of creating a CD-ROM of all described Sri Lankan species, complete with illustrations. They have also helped establish a reference collection of land snails at the Department of National Museums and another at the University of Peradeniya.

What drives her? "It’s curiosity really," she grinned. "That’s why I do it. I’m fascinated by natural history and curious to find out what’s happening in Sri Lanka in terms of the land snail fauna."

Snails as an indicator

"Snails act as an indicator because they share their forest habitat with lots of other species," she enthused. ""They can tell us how animals in forests might be coping or not coping with changes in forest cover. They can provide clues about how communities of species are structured. I’m using snails as a model to answer fundamental questions about the ecosystem."

It sounds like a language only biologists can understand but Fred volunteered to explain. Land snails can offer us a view of the past, he said. Their shells often remain preserved for long periods of time and can yield clues about the earth’s past climate. Land snails such as the large and beautiful tree snail Acavus have changed little since the world’s southern continents were joined together as the supercontinent Gondwana over 100 million years ago. They can provide insight into the rate of evolutionary change.

Scientists may also find interest in why Sri Lanka has such a large number of endemic snails — species that are not even found in India. Although the island does share many species of mammal, bird and reptile with the neighbouring country, this does not extend to snails. "That’s got to mean something," observed Fred.

Lack of interest

Fred and Dinazarde lament that, despite being fascinating and often beautiful creatures, snails are a neglected species in Sri Lanka. They are usually reviled for destroying plants, although Dinazarde pointed out that none of the major pest species are native to Sri Lanka — the introduction of exotic slugs and snails is a serious and growing problem.

"Next to being asked how to kill garden snails, the question we are most often asked is ‘what use are they’?" Fred and Dinazarde write in one of their colour guides. "This implies that the existence of organisms needs to be justified in terms of human values and human exploitation; it is not a view we share."

Dinazarde’s own interest in snails developed a few months after she left school, when she spen t a year rummaging in Sri Lankan forests with eminent naturalist the late P. B. Karunaratne — ‘Karu’, to his friends. A friend of the family, he was involved in a five-year survey of forest areas — studying various animal groups like mammals, birds, amphibians, reptiles and butterflies — and he had encouraged the young girl to become one of his field assistants. She moved fresh from her advanced level examination into Sri Lanka’s wilderness.

An old girl of Bishop’s College and Colombo International School, Dinazarde later shifted to Imperial College, London, for a degree in biology. Snails became an important focus of interest during her time as an undergraduate. She started visiting the neighbouring NHM because she knew it had Sri Lankan collections. "I wanted to identify the snails I had seen while working with Uncle Karu," she said.

The NHM collection

How had a museum in Britain acquired such a large collection of Sri Lankan snails? The answer lies with the Brits who roamed the country during colonial times, many of whom had strong naturalist inclinations. "We do have a massive collection of specimens, mostly put together during the 19th century," said Fred. "Britain was then a major influence in the world and Britons took their passionate interest in natural history wherever they went." Including ‘Ceylon’. And their zeal was not confined to snails.

"If anybody wants to do any work involving animals in Sri Lanka, the chances are that they will have to refer to our collections here," Fred said. "This is especially true where it concerns groups like snails."

These amateur British naturalists gathered samples of flora and fauna, trying to identify species and glean whatever information they could about them. This led to the formation of private collections around the world; these later came to the United Kingdom when their owners retired and returned home. Many of them left their collections as private legacies and the museum has largely built up its own collections from these private individuals. The museum’s haul often forms the basis of diverse study programmes.

Among those collectors who lived and worked in Sri Lanka were several members of the Layard family. The two Layard cousins, Edgar and Fredrick, made a particularly significant contribution to the study of Sri Lankan natural history and to our basic understanding of how many species there are in the country — not only of snails but of butterflies, birds, etc.

A large number of the snails they gathered are now at NHM. Layard’s Road in Colombo is named after another member of this family.

"It was fun"

In her first year and also immediately after her degree, Dinazarde and some friends conducted two field expeditions to Sri Lanka with funding from the university. Once again, she was trudging through forests, surveying distribution and collecting specimens. And it was quite enjoyable, she recalled.

"Sometimes we camped," she said. "Sometimes we climbed hills and often we walked quite deep into the forests. We saw birds, waterfalls, beautiful trees`85. It was fun."

Following graduation, Dinazarde started working part-time at NHM. Soon afterwards, she became involved in a collaborative project on Sri Lankan land snails between the NHM, Department of National Museums Sri Lanka and the University of Peradeniya. The project was funded by the UK government’s Darwin Initiative. It involved field research on land snails and their distribution; the establishment of land snail collections in Sri Lanka; and the publication of scientific and popular guides on the island’s land-snail fauna.

Launched at the 1992 UN ‘Earth Summit’ in Rio de Janeiro, Brazil, the Darwin Initiative seeks to help safeguard the worlds’ biodiversity by drawing on British strengths. It aims to assist countries that are rich in biodiversity but poor in financial resources by increasing their capacity for understanding and conserving their own biodiversity.

During the three-year Darwin project, Dinazarde studied land snails in different forests of Sri Lanka’s wet, dry and intermediate zones. This was followed with more detailed research in threatened forest patches of the wet lowlands. The latter study, which forms the focus of her PhD, looks at how forest snails deal with forest loss and land use change. For this, she explored lowland rainforests in the Ratnapura, Kalutara, Galle and Matara districts.

Over the next few years, Fred and Dinarzarde hope to publish the results of these investigations as popular articles, guides and as research papers in scientific journals.

Local knowledge

Currently completing her doctoral studies at the University of Cambridge and NHM, Dinazarde has gained valuable insight during the past few years. She has discovered, for instance, that some of the people who knew most about forests were the villagers who lived around them. "There are still local people with an incredible knowledge of forest plants and the uses of forest plants," Dinazarde said. "They don’t know them by scientific or botanical names. But they have a sophisticated system of classification which is quite impressive."

"We have come across people who are quick in picking up even Latin names," she continued. "A lot of people are desperate for information."

Dinazarde now hopes that more can be done to provide updated and scientific information on Sri Lanka’s plants and animals to people in rural areas.

"I think long-term conservation depends on empowering local people, people who actually live close to forests," she explained. "They are in the best position to protect those areas. I feel the solution lies in getting local people involved in managing their own resources."

(http://www.island.lk/2004/10/24/leisure1.html)