IUCN launches new publication on alien invasive species


Alien invasive species in Africa's wetlands launched on 5 February

IUCN-The World Conservation Union's Eastern Africa Regional Programme took the opportunity of UNEP's Governing Council meeting currently taking place in Nairobi, Kenya, to launch a new booklet, Alien invasive species in Africa's wetlands: some threats and solutions, by Geoff Howard and Susan Matindi, on behalf of IUCN, the Ramsar Convention on Wetlands, and the Global Invasive Species Programme (GISP). In an incisive 16 pages, the booklet outlines the threats and costs involved in the spread of invasive species of flora and fauna through the continent's wetlands and looks in more depth at a number of them, including water hyacinth Eichhornia crassipes, water lettuce Pistia stratiotes, water fern Salvinia molesta, Louisiana crayfish Procambarus clarkii, and common carp Cyprinus carpio, among others.

The new publication would not have been possible without the financial support of the MacArthur Foundation through IUCN and the Swiss Agency for the Environment, Forests and Landscape through the Ramsar Convention Bureau, as well as the contributions of NORAD to the Regional Wetlands Support Programme in Eastern Africa.

Technical information was gathered from many wetland experts around Africa, and the IUCN Invasive Species Specialist Group was acknowledged as having been extremely helpful throughout
- especially through its Global Invasive Species Database and Web site; the Global Invasive Species Programme provided stimulus and access to a range of expertise.

Further reports of the booklet's launch can be found on the Environment News Service, http://ens-news.com/ens/feb2003/2003-02-05-07.asp, and BBC News, http://news.bbc.co.uk/2/hi/science/nature/2730693.stm. More information about the booklet itself can be obtained from IUCN's Eastern Africa Regional Office.

from the booklet


Wetlands in Africa are increasingly being recognised as ecosystems of extreme importance to man and biodiversity. People derive many benefits from the goods and services provided by wetlands while wetland systems are the "homes" of very many species of animals and plants and their habitats. In Africa wetland awareness has been paralleled by the need to develop mechanisms for tropical wetland management - both to maintain the human benefits from wetlands and to secure their biodiversity into the future.

Management of African wetlands, as well as lakes and rivers, however, has been impacted by alien invasive species that specialise on aquatic (and semi-aquatic) systems and which cause damage to their human benefits and their biodiversity. These are species that come from "outside" and which arrive without their native controls - such as their own competitors, predators, parasites and pathogens. They are species which grow fast, spread quickly and cause all manner of problems in their "new" ecosystems. These aliens can be plants, animals or micro-organisms, they can be introduced to Africa intentionally or unintentionally, but nevertheless spread and cause problems wherever they establish and become invasive. In this case "invasiveness" usually means over-running local ecosystems and habitats, species and communities, human development and infrastructure. The damage caused by alien invasive species to African wetlands runs into the billions of dollars annually - but hard data is hard to acquire as the impacts of these species are only just being realised. Most well-known would be the Water Hyacinth - sometimes called "the world's worst water weed" - which has inflicted many millions of dollars of damage to Africa's wetlands, lakes, rivers, hydro-schemes, irrigation and water supply systems, fisheries and human welfare - not to mention its effects on Africa's aquatic biodiversity! And then there are the huge costs of control, to manage the invasive species and then to try restore the affected ecosystems to their previous condition - these also run into many millions of dollars per year continent-wide.

The Ramsar Convention on Wetlands of International Importance together with the Global Invasive Species Programme and IUCN - The World Conservation Union, have taken these matters to heart and, together, are promoting an understanding of wetland invasives - both from the aspect of biodiversity conservation and of human welfare. A first step is to raise the awareness of the people concerned (wetland residents, wetland managers, water managers, energy managers, irrigation managers, etc.) of the existence of alien invasive species already in Africa's wetlands and then the threats they pose in existing and future invasions. It is also necessary to provide some information on their identity, possibilities for control and sources of available information and technical assistance. Wetland invaders can rarely be eradicated, but they can usually be controlled if efforts to prevent their arrival have failed and if they have become established. Control is always expensive and time-consuming but can result in lasting ecosystem integrity.

Many of the organisms that invade wetlands in Africa also have their traditional and new uses. Plants are often used for fibre, building materials, energy, mulch and stockfeed. Aquatic animals like fish and some crustaceans become invasive when introduced to enhance fisheries - where they become very valuable. But it should be noted that uses of alien invasive species, however diverse, will not alone result in their control.

This booklet introduces alien wetland invaders by describing seven of the worst already introduced to Africa while mentioning others that "are coming". It also tries to distinguish between alien invasive species and those native species that also cause problems - with examples of two that affect African wetlands - although there are many others. But primarily this publication is intended to bring to peoples' attention the existence and threats of alien invasive species generally, and those that affect aquatic ecosystems in Africa in particular.

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