Valuing biodiversity services, including its insurance against disease

October 25, 2005

By diluting the pool of virus targets and hosts, biodiversity reduces their impact on humans and provides a form of global health insurance, biodiversity experts say.

At the same time, intrusion into the world's areas of high biodiversity disturbs these biological reservoirs and exposes people to new forms of infectious disease, according to Dr. Peter Daszak, one of 700 experts from 60 countries convening in Oaxaca, Mexico for a landmark conference dedicated to the convergence of all biodiversity-related sciences.

Identifying the value to people of biodiversity-related ecosystem services such as disease regulation, climate regulation, storm protection and habitat for useful species is the main theme of the First DIVERSITAS Open Science Conference, Nov. 9-12, co-hosted by the Mexican government. Some 450 presentations are scheduled in issue areas ranging from biology to conomics and international law, with emphasis on the positive benefits of conservation.

Biodiversity not only stores the promise of new medical treatments and cures, it buffers humans from organisms and agents that cause disease, according to Dr. Daszak, Executive Director of the Consortium for Conservation Medicine, at Wildlife Trust, New York, and member of the DIVERSITAS Scientific Steering Committee.

Growing human contact with wildlife through invasion of forest habitat and the use of wildlife for food and folk remedies is responsible for the emergence of a series of lethal human diseases that originated in animals, most famously SARS, HIV-AIDS and Ebola, he says, adding that preventing emerging diseases through biodiversity conservation is far more cost effective than developing vaccines to combat them later.

Part of a scientific team that recently connected Asian bats in China with the SARS virus, Dr. Daszak says it's important to draw lessons from that $50 billion global health crisis when looking ahead to the Asian bird flu and health problems yet to emerge.

"Cutting down contact between wildlife, domestic animals, poultry and people is the way to reduce the risk of spreading disease," says Dr. Daszak: "Persuading policy makers of this is the big challenge. The key is to understand the process of emerging infectious diseases so that we can deal with them proactively before they become a major health threat."

As with many environmental issues, scientists now realize that a range of measures are involved in preserving ecosystem services such as disease regulation, including sanitary and health directives, education, capacity building, price and tax measures.

Valuing Biodiversity

The Oaxaca conference assembles many perspectives from the natural and social sciences to highlight the causes and consequences of biodiversity loss. Following closely the Millennium Ecosystem Assessment launch, it examines changes in beneficial ecosystem services and the economic causes and consequences of biodiversity loss.

"We are only beginning to understand the relative importance of biodiversity in the provision of services and the trade-offs involved different conservation and development options," says Arizona State University Professor Charles Perrings, Vice-Chair of the DIVERSITAS Scientific Steering Committee.

"People have to decide what to conserve or use, where to conserve or use it, and what mechanisms to use. The DIVERSITAS conference represents a landmark event in policy-relevant science, showing how science is being harnessed to help develop conservation strategies by analyzing the benefits offered by different strategies."

"The value of services provided by nature and its diversity is under appreciated until they stop," says Anne Larigauderie, Executive Director of Paris-based DIVERSITAS.

"Examples abound of services provided free by nature for which expensive artificial replacements are now required. In one part of China, for instance, the loss of bees to pollinate apple trees has caused orchard owners to hire people to do the job. Elsewhere, the loss of microbes that helped keep soil fertile forces farmers to turn to fertilizers."

"There is a very positive story to be told about the social benefits of investment in conservation," says Dr. Larigauderie. "Unfortunately, because these services are so difficult to value, the benefits derived from them are often ignored in policy decisions and private activities that lead to irrevocable environmental change. The result: disappearing natural ecosystems, biodiversity loss, and the decline of beneficial ecological functions."

Biodiversity and the dynamics of infectious disease

In the case of disease regulation, the costs of ecological service degradation are the costs of the diseases themselves.

Among other presenters, Scientists Matt Thomas, Kevin Lafferty and Carolyn Friedman say increases or decreases in species richness and composition affect the dynamics of infectious disease.

In a joint paper to be introduced at the conference as part of a new DIVERSITAS book, they say diversity of both disease agents and their hosts play an important role in disease dynamics in natural as well as managed systems.

For example, pre-infection with one type of virus reduces the death rate in shrimp and rainbow trout when subsequently infected by a more deadly virus. Meanwhile, in an experiment in China, farmers who planted a sacrificial row of rice susceptible to a disease every four to six rows were able to control "rice blast" disease in the rest of the crop and increase yield.

However, Dr. Thomas and colleagues note that presence of other species not directly linked to a particular host-pathogen combination can also influence disease risk and spread. One factor implicated in the increased prevalence of Lyme disease in the eastern U.S., for example, is a reduction in the predators that check the populations of white-footed mice, the main reservoir of the disease. They also note that the impact on humans of Lyme disease in the U.S. decreases in states with more varied potential targets for the ticks that transmit the disease, such as small mammals and lizards.

Conference participants will also learn how West Nile Virus (WNV) carrying mosquitoes prefer some bird species and avoid others, how additional species are likely to be impacted, how impacts might be reduced, and how to reduce the risk of WNV mosquitoes from infecting the unique bird populations of Hawaii and the Galapagos.

Dr. Daszak says the prospect of West Nile Virus entering Hawaii via aircraft is both serious and growing.

"We estimate that up to 70 West Nile-infected mosquitos are going to land in Hawaii every year for the foreseeable future. It's a big risk. If WNV gets into Hawaii it will cause human deaths, cost millions of dollars in health care and affect Hawaii's tourist trade. It will also probably affect some of the native birds and possibly cause extinctions. The highly endangered Hawaiian crow is particularly at risk.

"Knowing this we can act to cut down on the risk of WNV mosquitoes hitching a ride on planes by using residual insecticides inside the cargo holds."

Other research to be showcased at the conference describes:* * * * *

First DIVERSITAS Open Science Conference

Integrating biodiversity science for human well-being

9-12 November 2005,
Hotel Mision de Los Angeles, Oaxaca, Mexico

More than 700 leading natural and social scientists from 60 countries will attend the first open science conference, convened Paris-based DIVERSITAS to integrate knowledge about the relationship between humans and the world's biological resources.

Goals of the conference:Key questions to be addressed include:More than 450 presentations will reveal recent findings across virtually all ecosystems, explain the development and application of new technologies, and challenge current thinking about human activities that are having the greatest impact on biodiversity change.

Sampling of Symposia Topics:

  • Understanding and managing biodiversity conflicts
  • Sustaining partnerships for community-based conservation
  • Implementing multilateral environmental agreements on biodiversity: Balancing equity and effectiveness
  • Biodiversity, human-well-being, and the Millennium Ecosystem Assessment
  • Wildlife conservation and economic development in East and Southern Africa ecoSERVICES
    • Biodiversity and litter decomposition: A cross-systems perspective
    • Symposium on pollination services
    • Forest biodiversity and carbon sequestration
    • The insurance value of biodiversity
    • Marine biodiversity and ecosystem functioning
    Cross-cutting Networks
    • Biodiversity in agricultural landscapes: How to save our capital and not lose interest
    • Eco-health and conservation medicine: A new agenda for public health and biodiversity
    • Diversity, diversification processes and conservation of high mountains biota
    • Freshwaters: Sustaining biodiversity and system integrity
    • Impacts of invasive alien species on ecosystem services
    DIVERSITAS: An international programme of biodiversity science DIVERSITAS brings together biological, ecological and social sciences to address key questions that underlie our limited understanding of the current situation.
    • How much biodiversity exists and how does its change or loss affect the system as a whole?
    • How does biodiversity correspond to the delivery of ecosystem functions and services, and what is the true value of these commodities?
    • How can scientific investigation support policy and decision making to encourage more sustainable use of biodiversity?
    Armed with a broader, deeper knowledge of biodiversity, we will be better equipped to safeguard the future of Earth's natural resources.
    For more information, including media registration: or


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