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Most aquatic ecosystems aredisturbedbyoneormoredriving forces, generallyof humanorigin.
Thesedriving forcesmakeuseof the aquatic ecosystems andgeneratedifferent typesof pressure
(pollutiondischarge, damwater storage, etc.) that canbe identifiedby the above-mentioned
parametersused todetermine the stateof the aquatic environment. Thesepressuresgenerallyhave
an impact onbiological factors. The causal frameworkDPSIR / Driving forces - Pressures - State -
Impact -Responses (adoptedby theEuropeanEnvironment Agency) provides a suitable structure
for analysis.
2.1.3 Ecosystem functions
The parameters are used to qualify and/or quantify the key functions of aquatic ecosystems.
Ecosystem functions are defined as a subset of the interactions between biophysical
structures, biodiversity and ecosystem processes.
An aquatic ecosystem in good condition can carry out diverse functions that can be grouped
into several families:
n
Production functions, whichmostly concern the production of organicmatter, the
availability of non-renewable resources likewater, andmineral substances;
n
Regulation functions - theway ecosystems function contributes to stabilizing the
variability of natural processes (climate, natural risks, etc.) and resource flows
(soil water retention). They also play a role in eliminating the transformation of toxins
(water self-purification);
n
Organization (or structuring) functions - these contribute to defining the system’s
self-organization rules. They involve the physical organization of systems (landscape
structuring) and their biological organization (biodiversity).
2.1.4 Ecosystem services
An aquatic ecosystem hasmultiple functions, which is highly important in a finite environment
because it generatesmany benefits and services. These services are called ecosystem services
and are usually defined as the benefits that humans derive from ecosystem functions. The
sustainable functioning of these ecosystems should therefore be a target for watermanagers
andmany studies have shown that they are crucial to sustainable economic activity.
Each individual ecosystem forms the basis of functions that themselves generate services.
Several alternative classifications of ecosystem services exist (The Economics of Ecosystems
and Biodiversity, MillenniumAssessment, Common International Classification of Ecosystem
Services, as examples). They include three or four types of service (provisioning, regulatory,
cultural and sometimes a fourth category of supporting services):
n
Provisioning services include products resulting from ecosystems (food andwater
resources, diversematerials, fibres, genetic and biochemical resources, and othermineral
resources);
n
Regulatory services are the benefits resulting from the regulation of ecosystemic
processes (i.e. climate regulation, hydrological regulation, water purification and
treatment, regulation of natural risks and disease, erosion and sedimentation, pollution
filtration);
n
Cultural services include non-material benefits resulting from ecosystems (recreation and
well-being services, religious and spiritual services, aesthetic value, education and cultural
heritage);
n
Supporting services comprise soil formation, the nutrient cycle and thewater cycle.
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THEHANDBOOK FORMANAGEMENT
ANDRESTORATIONOF AQUATIC ECOSYSTEMS INRIVERAND LAKE BASINS
2FUNCTIONSANDBENEFITSOFAQUATICECOSYSTEMS
