Module 1:

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Developing legal and institutional frameworksfor
invasive alien species
Module 1 what decision-makers need to know about
invasive species
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what this module covers

• what invasive alien species and invasion
  means
• pathways for species introductions
• impacts of IAS
• problems of prediction and links to other
  environmental pressures
• the importance of information and available
  international resources

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what are invasive alien species?

• many different terms a complex area

an alien species is a species that has been
introduced to a location (ecosystem or area)
where it does not occur naturally an invasive
alien species (IAS) is an alien species that
causes (or has the potential to cause) harm to
the environment, economies and/or human health
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introductions are nothing new...
...but globalisation has led to massive expansion
of opportunities for introductions
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what type of species invade?

• from all taxonomic groups
• vertebrates (e.g. mammals, fish, birds, reptiles)
• invertebrates (e.g. insects, snails, worms)
• aquatic, marine and terrestrial plants (e.g.
  weeds, trees)
• micro-organisms (e.g. viruses, bacteria)

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Process of Invasion
1. Introduction
intentional or unintentional
2. Establishment
survives but doesnt spread
(a) naturalisation becomes part of new
habitats flora/fauna
3. Spread
(b) invasion expands and impacts on species,
ecosystems people and development
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1. Introduction 2. Establishment 3a.Spread -
Naturalisation 3b. SPREAD - INVASION
the House Sparrow spreading and invading Tanzania
over 90 years
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• Many IAS undergo a lag phase after initial
  establishment, and may remain unobtrusive before
  becoming invasive and spreading rapidly
• In some species (e.g. trees) this may be more
  than 100 years, in others (e.g. water hyacinth)
  it may be a few weeks

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habitat occupation changes during invasion
Introduction
Invasion
Consolidation

• Process of Invasion from Introduction to
  Consolidation
• (after Williams, 2003)

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Invasions can thus be stopped at several stages

• best is prevention stopping introductions
• next best is eradication destroying or removing
  a new invasion
• third is containment stopping a new invasion
  from further spreading
• last (and most expensive and time-consuming) is
  management of established invasions restoration
  of affected systems
• Sequence endorsed under Convention on Biological
  Diversity

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how do species get moved around?

• Vectors The specific mechanism by which a
  species is moved along a pathway (clothing,
  vehicle, boat hulls, ballast water, packaging,
  soil around plant roots...)
• e.g. a tourist carrying seeds is a vector in the
  pathway of international airline flights
• Pathways The routes along which a species is
  moved or moves itself (roads, railways, air
  corridors, shipping lanes, rivers) ... including
  trade itself

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Shipping routes now reach every continent (even
Antarctica) and air travel reaches most cities in
the world
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ballast water

• a major vector for unintentional introductions in
  the shipping pathway
• up to 14 billion tonnes of ballast water
  transported around the world each year
• an estimated 7 000 10 000 species may be
  present in ballast water at any given time

Zebra mussels were introduced to the Great Lakes
of North America in ballast water in the 1980s,
and now cause severe economic impacts
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direct indirect causes of introductions
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introduction of species
Movement by human action of a species outside its
native range can result in introduction
(into/within a country)
Some establish, naturalise and spread
Some establish, naturalise and spread
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• intentional introduction

• unintentional introduction

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impacts of IAS

• negative impacts on
• ecosystems
• economies
• human health

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ecological impacts

• direct predation/herbivory
• competition for resources/exclusion (e.g. light,
  food)
• transmission of pathogens and parasites
• alteration of micro-climate, nutrient
  availability, ecoystem cycles (energy, water,
  minerals, organics)
• disturbance to ecological processes (e.g.
  pollination)
• disruption of ecosystem services (e.g. flood
  attenuation)
• environmental degradation, facilitating further
  invasions

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economic impactsestimated at 5 global GDP

• Direct costs
• Direct loss of crops, reduced yields
• Lost export earnings
• Loss of tourism revenues
• Management costs
• Indirect costs
• Impaired ecosystem services
• Damaged infrastructure
• Costs to natural environment and societal or
  cultural values

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health impacts

• Direct impacts
• Disease
• Allergic reactions
• Injuries through stinging or biting
• Indirect impacts
• Providing a vector for disease

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Millennium Ecosystem Assessment /Emerson Howard
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Lantana camara is a classic IAS which (after 160
years) is still spreading across Africa and
invading new lands - as well as in Australia,
Asia and North America
Lantana replaces native vegetation and pasture,
is poisonous to livestock and harbours tsestse
flies and rats
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an example of spread and invasion impacts
The Kafue Floodplain was home to many wild
animals and plants cattle grazing, fishing,
conservation tourism
Kafue Floodplain, Zambia, dry
1974
Kafue Floodplain flooded

• In 1974 there was an occasional plant of Mimosa
  pigra on the edges of the Kafue River

1974
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Mimosa pigra (continued)

• A heavy flood in 1981/2 brought a few plants of
  Mimosa pigra on to the floodplain

(which was a new ecosystem changed by a dam
upstream)
1982
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Mimosa pigra (continued)

• After a slow start in the late 1980s, M. pigra
  began to spread
• By 2000 it was covering a few hundred hectares

2001
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Mimosa pigra (continued)

• By 2007 it was growing up to 4m high and covering
  3,000 hectares

2007
. and excluding almost every other plant and
most animals .
2007
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Mimosa pigra continued
3,000 ha of an available 12,000 ha are now covered

• Today
• no livestock
• no fisheries
• no tourism on this part of the Kafue Floodplain

costs to livelihoods production
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invasion impacts human development

• Water hyacinth affecting Kafue Gorge Dam and
  hydropower station, Zambia
• (photo M. Mumba)

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impacts on production (eco)systems

• ecosystems, native or cultured, that are used for
  food and commodity production can also be invaded
  by alien species
• forestry, fisheries, agriculture, aquaculture
• parasitism, pathogenesis, predation, competition,
  exclusion and destruction of productive systems
  are all recorded most known from farming,
  horticulture and livestock production

Tall trees of Senna spectabilis from S. America
replacing native forest in Uganda
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Invasiveness of an alien species

• what makes a good invader?
• rapid growth rate
• great dispersal characteristics
• large reproductive capacity
• broad environmental tolerance
• effective competitor with local species

Lianes in Seychelles
all invasive plants can be called weeds BUT not
all weeds are invasive species
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current and future trends

• human activities are changing natural ecosystems
  and making them more susceptible to IAS
• globalisation
• land-use change
• climate change

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invasives and climate change

• climate change is upon us - although not exactly
  predictable in area or extent
• climate change will make ecosystems more
  vulnerable to invasions
• invasive species are already taking advantage
  of changed climatic conditions and expanding to
  the detriment of local species, habitats and
  ecosystems
• thus we must be prepared for ecosystems affected
  by climate change to be further invaded and we
  must develop tools to predict and prevent these
  extra invasions

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• causes and effects of IAS are international or
  regional

IAS management and control supported by
bilateral, regional and global instruments and
guidance (see Modules 2 6)
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emerging principles of IAS management
Convention on Biological Diversity 1992 (CBD)
Parties to prevent the introduction of, control
or eradicate those alien species which threaten
ecosystems, habitats or species (Art.8(h))

• the precautionary principle
• the principle of preventive action
• the ecosystem approach
• sharing of information
• user-pays principle
• cross-sectoral approach to management

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Sharing of expertise and information is crucial

• Types of information to be shared?
• Inventories and databases
• Incident lists and case studies
• Potential threats to neighbouring countries
• Information on taxonomy, ecology and genetics of
  IAS
• Prevention and control methods where available
• National and regional guidelines and measures
• Many IAS databases accessible electronically

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Some GISP products that can help