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Invasive alien species

The Giant Mimosa (Mimosa pigra)


The impacts of invasive alien species are immense, insidious, and usually irreversible. They may be as damaging to native species and ecosystems on a global scale as the loss and degradation of habitats.

In the past, the natural barriers of oceans, mountains, rivers and deserts provided the isolation essential for unique species and ecosystems to evolve. In just a few hundred years these barriers have been rendered ineffective by major global forces that combined to help alien species travel vast distances to new habitats and become invasive alien species. The globalisation and growth in the volume of trade and tourism, coupled with the emphasis on free trade, provide more opportunities than ever before for species to be spread accidentally or deliberately. Customs and quarantine practices, developed in an earlier time to guard against human and economic diseases and pests, are often inadequate safeguards against species that threaten native biodiversity. Thus the inadvertent ending of millions of years of biological isolation has created major ongoing problems that affect developed and developing countries.

The scope and cost of biological alien invasions is global and enormous, in both ecological and economic terms. Invasive alien species are found in all taxonomic groups: they include introduced viruses, fungi, algae, mosses, ferns, higher plants, invertebrates, fish, amphibians, reptiles, birds and mammals. They have invaded and affected native biota in virtually every ecosystem type on Earth. Hundreds of extinctions have been caused by alien invasives. The ecological cost is the irretrievable loss of native species and ecosystems.

IUCN indicate that the direct economic costs of invasive alien species run into many billions of dollars annually. Arable weeds reduce crop yields and increase costs; weeds degrade catchment areas and freshwater ecosystems; tourists and homeowners unwittingly introduce alien plants into wilderness and natural areas; pests and pathogens of crops, livestock and forests reduce yields and increase control costs. Factors like environmental pollution and habitat destruction can provide conditions that favour invasive alien species.

The degradation of natural habitats, ecosystems and agricultural lands (e.g. loss of cover and soil, pollution of land and waterways) that has occurred throughout the world has made it easier for alien species to establish and become invasive. Many alien invasives are "colonising" species that benefit from the reduced competition that follows habitat degradation. Global climate change is also a significant factor assisting the spread and establishment of invasive alien species. For example, increased temperatures may enable alien, disease-carrying mosquitoes to extend their range.

Sometimes the information that could alert management agencies to the potential dangers of new introductions is not known. Frequently, however, useful information is not widely shared or available in an appropriate format for many countries to take prompt action, assuming they have the resources, necessary infrastructure, commitment and trained staff to do so.
Few countries have developed the comprehensive legal and institutional systems that are capable of responding effectively to these new flows of goods, visitors and 'hitchhiker' species. Many citizens, key sector groups and governments have a poor appreciation of the magnitude and economic costs of the problem. As a consequence, responses are too often piecemeal, late and ineffective. Wetland ecosystems in particular are more vulnerable IUCN has identified the problem of invasive alien species as one of its major initiatives at the global level and

Developing a strategy to combat IAS in the Lower Mekong Basin
Wetlands in the Lower Mekong Basin have not been spared from the threat of IAS. Some significant species affecting the ecology and livelihood include the Giant Mimosa (Mimosa pigra) and the Golden Apple Snail (Pomacea sp.).

The initial task would be the compilation of existing information and development of a comprehensive list of IAS and a basin wide risk assessment identifying the category of threat. The MWBP will conduct a review of existing legal and technical mechanisms to manage and control invasive wetland species known to be a threat to biodiversity in the Mekong basin.

Through partnership, the MWBP will be developing and facilitating the implementation of a strategy to combat IAS affecting wetlands in the Lower Mekong Basin. In particular, the MWBP will build of the past an on-going efforts of the Invasive Species Specialist Group (ISSG) and other experts on invasive alien species.

The strategy and guidelines developed will also aim to assist the riparian governments and management agencies to give effect to Article 8 (h) of the Convention on Biological Diversity, which states that: "Each Contracting Party shall, as far as possible and as appropriate: …Prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species."

These proposed strategy and guidelines will be fine-tuned to address the root-causes resulting in the introduction of IAS in the LMB.

Parallel to the development of the strategy, priority interventions at the site level (e.g. in addressing the Mimosa pigra issue in the Plain of Reeds, Vietnam) will be implemented. The MWBP will support the implementation of current mechanisms and test new mechanisms in addressing the key issues relating to IAS.

It has also been noted that selected species of IAS in the LMB region have numerous alternative uses. There is no question about the economic benefits derived from certain introduced species that are considered invasive. The MWBP will attempt to use economic tools to assess the costs and benefits of selected species that might be considered invasive.
It is anticipated that the proposed strategy will identify specific interventions with focus on the following aspects and more.
To increase awareness of invasive alien species as a major issue affecting native biodiversity and ecosystems.
To encourage necessary research and the development and sharing of an adequate knowledge base to address the problem of invasive alien species.
To encourage prevention of invasive alien species introductions as a priority issue requiring regional, national and site level actions
To minimise the number of unintentional introductions and to prevent unauthorised introductions of alien species.
To ensure that intentional introductions, including those for biological control purposes, are properly evaluated in advance, with full regard to potential impacts on biodiversity.
To encourage the development and implementation of eradication and control campaigns and programmes for invasive alien species, and to increase the effectiveness of those campaigns and programmes.
To encourage the development of a comprehensive framework for national legislation and international cooperation to regulate the introduction of alien species as well as the eradication and control of invasive alien species.