Biodiversity, Environment, Global, Global Geopolitics, Headlines, Latin America & the Caribbean

BIODIVERSITY: Islands – Paradise Invaded

Mario Osava

RIO DE JANEIRO, Apr 14 2006 (IPS) - Many countries, including Brazil, are only just waking up to the threat that invading species can pose to islands, generally seen as natural paradises and tourist attractions.

A recent Brazilian government inventory of the fauna on islands off the country’s Atlantic coast simply listed exotic invasive species without identifying them as such, said Silvia Ziller, executive director of the Horus Institute in Brazil, and coordinator of the international Nature Conservancy’s South American programme on invasive species.

Conserving biodiversity on islands is one of the top priorities of the Convention on Biological Diversity, whose eighth conference of parties (COP8) ended two weeks ago in Curitiba, in southern Brazil. They are repositories of a rich variety of species that are often unique, and are extremely vulnerable.

Invasion by foreign species is the main cause of loss of biodiversity and damage to the ecosystem on many islands around the world, according to Alan Saunders, an expert at the University of Auckland, New Zealand, and director of the Cooperative Islands Initiative, which has implemented a programme in the Pacific, and seeks to coordinate efforts and raise awareness on the problem.

According to estimates, invasive species are to blame for more than 55 percent of the island bird species that have become extinct in the course of history, and for a large proportion of the disappearances or reduced populations of reptiles, mammals and plants.

Because of their isolation and their limited surface area, islands are highly vulnerable to invasive species. But at the same time, they have certain advantages when it comes to prevention against and eradication of these species. For instance, island populations usually rally to the defence of the natural resources on which their livelihoods depend, Saunders told participants at the Curitiba meeting.

The more than 100,000 islands in the world account for only five percent of the total land mass, but are home to 500 million people. Islands provide nearly half of the areas vital to bird life, and harbour about one-third of critically endangered mammals, birds and amphibians.

But there is little awareness in South America of the perils facing islands, and recent actions taken against invasive species are still based on a short-term economic view, such as in response to agricultural losses, Ziller told IPS. National programmes, however, have begun to emerge, and non-governmental organisations are trying to build a Latin American information network on the issue.

In Argentina, the National University of the South is building a databank on invasive species, and “produces a lot of information about them, but without government action we cannot tackle the problem,” said Ziller. Regulations, risk analysis and border controls are needed, which only the government can provide, she underlined.

Ecuador’s Galapagos Islands are a successful example of fighting alien species before they can do irreversible harm to the native wildlife, she said.

The project, financed by the Global Environment Facility, has been implemented since 2001 by various Ecuadorean institutions. It has already eradicated goats from Santiago Island and the north of Isabela Island, and wild blackberries from Santa Cruz Island.

About one hundred foreign plant species have been introduced on the Galapagos Islands. The risks they pose are being evaluated, and plans to eliminate about a dozen are under way, said Anita Sancho, coordinator of invasive species eradication programmes on the islands.

An inventory of the foreign plants identified 80 new species in the last three years alone. With so many tourists visiting the islands, preventing the introduction of alien species calls for very strict control of both carry-on and unaccompanied luggage, at the Galapagos airport and at the airports in Quito and Guayaquil, where flights to the Galapagos Islands originate.

The project will continue until 2007, but some lessons have already been learned, such as the essential need for grassroots participation, and for people to empathise with the project’s aims. As this was a pioneer effort with regard to its scope, there were no previous examples to guide the initial planning, making it harder to implement, Sancho emphasised.

Exotic invasive species “not only affect biodiversity, but also entail high social costs, in terms of people’s health when diseases are introduced, and economic costs,” she told IPS. Insects brought dengue fever and malaria to the Galapagos, and wild blackberries deprived livestock of land and fodder, she explained.

In Brazil, most people don’t realise that the Fernando de Noronha archipelago, a symbol of natural paradise in the northeast of the country, is threatened by invaders such as goat, mice and other rodents, tegu lizards, cats, creepers and fodder plants, Ziller said.

Many of these species were introduced centuries ago: rats were left behind by ships, and sailors deliberately left goats, trusting to their ability to survive and breed in nature, to be sure they would have food on future visits. But others have arrived recently, such as leucaena, a leguminous tree originally from Central America, used as fodder for goats.

The control and eradication of foreign species sometimes requires measures that are opposed by environmentalists, such as the use of herbicides in Hawaii to eliminate invasive plants in remote mountainous areas, or the hunting of animals that destroy seedlings or threaten biodiversity, Ziller stated.

Some inland areas also face risks similar to those afflicting islands. Brazil’s Iguaçu National Park, located on the border with Argentina and Paraguay, is totally surrounded by soy plantations and other lands completely altered by human activity, and other small conservation areas are also isolated and threatened by exotic species, she noted.