A European study for the first time evaluated the ecological damage and financial cost of
invasive species in Europe (e.g. toxic algae, coypu, Canada geese, zebramussel, etc.).
The study was based on the European project Daisie (Delivering Alien Invasive Species
Inventories for Europe) launched in 2005.
This programme led to an inventory of all alien species introduced onto the European continent
since the discovery of America in 1492. Of the 10,000 species listed, 1,094 (11%) appear to
have an ecological impact and 1,347 (13%) have an economic impact. Land vertebrates and
invasive freshwater plants and animals appear to do themost damage to crops and forests in
terms of cost, explained INRA. Thus, the invasive species that incur the greatest financial cost
each year include single-celled toxic algae in Norway (8.2million euro/year), water hyacinth in
Spain (3.4million euro/year) and the coypu in Italy (2.8million euro/year). Land vertebrates like
the coypu and themuskrat appear to have the highest combined ecological and financial
impact, causing damage in over 50 European regions.
Scientists’ objective in this study is to help prevent risks caused by the arrival on the continent
of other potentially harmful alien species.
Reference: Front Ecol Environ 2009
Box 5: Evaluation of damages caused by invasive species in Europe
15
2.2Human activities and pollution sources
Human beings are key users of aquatic ecosystems and associated ecosystem services. This
usemay be conscious or not, and, depending on its intensity, may have little or no effect on
the aquatic environment, ormay generate significant effects, often known as dysfunctions.
This chapter describes themain human activities that use aquatic ecosystems and themain
dysfunctions, with a separate focus on pollution, split into the four categories of parameters
identified in the previous chapter.
2.2.1 Biology: Modifications of the biocenosis - Invasive alien species
In aquatic ecosystems, all living species (i.e. thebiocenosis) operate interdependently in a relatively
balancedway via the food chain and thepyramidof productivity. Thisbalance canbedisturbed and
brokenby, for example, thedisappearanceof oneor several species, or the introductionof invasive
alien species.
Theproliferationof invasive alien species threatensbiodiversity andhas an impact onhumanhealth.
This is the case, for example, for plant species likewater primrose, giant hogweed, Japanese
knotweed andMyriophyllum spicatum,whether or not they are introduced intentionally. These
invasiveplantsgrow rapidly and supplant indigenous species; theydevelop excessively, reducing the
concentrationof oxygen, asphyxiating thenatural aquatic environment and endangering fish and the
development of other aquatic species.
Invasive alienplants canhave consequencesonhumanhealth. For example, thepollenof some
plants (e.g. common ragweed) provokes allergies like rhinitis, conjunctivitis, asthma, hives and
eczema. Invasive alien species can alsohave economic consequences, such as affecting agriculture,
livestockproduction and fishing, or anegative impact on tourism and leisure activities (e.g. bathing,
sailing).
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THEHANDBOOK FORMANAGEMENT
ANDRESTORATIONOF AQUATIC ECOSYSTEMS INRIVERAND LAKE BASINS
2FUNCTIONSANDBENEFITSOFAQUATICECOSYSTEMS
