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Newsletter and Technical Publications
Freshwater Management Series No. 5
Guidelines for the Integrated Management of
the Watershed
- Phytotechnology and Ecohydrology -
9. ECOLOGICAL INTEGRITY ASSESSMENT AS A STRATEGIC
COMPONENT OF SUSTAINABLE WATER MANAGEMENT1
A. Integrated management of river basins: general recommendations
The decline of water quality and biodiversity at the
global scale is sobering evidence that effective water management requires
effective, easy-to-use tools and relevant, efficient techniques to control
excess nutrients, pollutants, minerals, and organic materials being transferred
from modified landscapes into freshwater ecosystems (Zalewski et al. 1997).
This requires the
integration of sound scientific principles with watershed-based management
perspectives that consider the riverine landscape as an extensive series of
interconnected biotopes along an environmental gradient (that provides a framework
for the broad-scale ecosystem patterns and processes) associated with the
respective biotic communities. These new perspectives for the effective
management and conservation of water resources can be achieved through the
application of catchment-based approaches utilising the principles of
ecohydrology (Table 9.1). Through this strategic approach, the sustainable
management of running waters (sensu
Ward 1998) becomes a matter of:
- re-establishing the environmental gradients along longitudinal,
lateral, and vertical dimensions and across a range of scales,
- re-establishing the ecological connectivity between landscape
elements, based on facilitating matter and energy exchange, with successive
improvements in the buffering capacity of
the ecosystems against anthropogenic impacts,
- reconstituting some semblance of the natural fluvial dynamics
that promote and sustain high levels of biodiversity,
- maintaining the natural structure and functioning of aquatic
ecosystems based upon a multidimensional examination and understanding of
biodiversity patterns.
Ecological assessment methodologies, therefore, are an
integral part of sustainable river basin management.
B. Landscape analysis of aquatic ecosystems
The basic concepts of the Clean Water Act (U.S. Environmental Protection
Agency 1999) and the European Union (EU) Water Framework Directive (2000) are
oriented toward the protection of the ecological integrity of freshwater
systems. Underlying these policies is the assumption that the biotic structure
and water quality of streams and rivers reflects an integration of
physical and biological processes occurring in a catchment. Consequently, an
integrative, multiple-scale analysis of landscape properties in given
ecoregions has become an obligatory approach for the integrated catchment
management. An hierarchical landscape analysis, utilising Geographic
Information Systems (GIS) techniques, provides the structural and functional
descriptors of regional-scale interactions: geomorphological gradients, climatic
changes, hydrologic pathways, and locations of human activities that alter land
cover and ultimately affect most of landscape-freshwater couplings
(Bis et al. 2000) (Figure 9.1) can be
integrated within a GIS environment. A refined understanding of scale-dependent
processes and the hierarchy of linkages across the catchment is crucial to
ecologically-sound water management, human impact assessment, and effective
protection of in-stream biota. Inherent in this approach are the new
perspectives in resource management, policy decision-making, and environmental
problem-solving (within political and management jurisdictions).
1 This contribution
presents part of the catchment-based monitoring and assessment studies
undertaken during EC fellowships (the European Training Foundation, No
IMG-97-PL-2157) in ALTERRA (Green World Research, Wageningen, The Netherlands)
and URA CNRS ‘Ecologie des Eaux Douces et des Grands Fluves' (Universit' Lyon
I, France).
Table 9.1. A comparison of the fundamental concepts
in lotic ecology applicable to
freshwater monitoring and management at various spatial and temporal scales
| Ecological concepts |
Key thesis |
Spatial scale |
References |
| Intermediate Disturbance Hypothesis |
Disturbance intensity
and frequency vs. species diversity |
stream, valley |
Connell 1978 |
| River Continuum Concept |
Longitudinal gradients;
energy input and transfer; maximisation of energy utilisation through species
replacement; longitudinal biodiversity patterns (maximum of species richness in
the midreaches); |
stream, valley |
Vannote et al. 1980 |
| Nutrient Spiralling Concept |
Longitudinal nutrient
cycling (average distance associated with one complete cycle of a nutrient) |
stream, valley |
Newbold et al. 1981 |
| Serial Discontinuity
Concept |
Discontinuity through
human interference |
stream, valley |
Ward and Stanford 1983 |
| Biotic and Abiotic
Control Concept |
Shift in the hierarchy
of abiotic factors regulating aquatic communities along a river continuum under
different temperature regimes |
stream, valley |
Zalewski and Naiman 1985,
Power et al. 1988 |
| Stream Hydraulics
Concept |
Hydraulic transition
zones; physical characteristics of flow (stream hydraulics) as a major
determinant of faunistic zonation patterns in pristine streams |
stream, valley |
Statzner and Higler 1986 |
| Fluvial Hydrosystem
Concept |
A scaling of fluvial hydrosystem into
(a) the drainage basin,(b) functional sectors,
(c) functional sets, (d) functional units, and (e) mesohabitats |
stream, valley |
Amoros et al.
1987, Petts and Amoros 1996 |
| Disturbance-Productivity
Concept |
Predictive trends of
species richness and productivity along a gradient of disturbance frequency |
stream, valley |
Hildrew and Townsend
1987 |
| Riparian Ecotones
Concept |
Transitional zones, with
specific physical, chemical, and biological properties, possessing unique
interactions with adjacent ecological systems |
stream, valley |
Naiman et al. 1988 |
| Flood Pulse Concept |
Lateral transfer of
substances; flow dynamics (wetlands and forests minimise pulse effects) |
lower stream reaches,
valley |
Junk et al. 1989 |
| Hierarchy Theory |
Ecosystem processes and
functions operating at different scales form a
nested, interdependent system, where one level influences other levels
above and below it |
multiple spatial scales |
Allen and Starr
1982
O’Neil et al. 1989 |
| Patch Dynamic Concept |
Spatial and temporal
heterogeneity vs. biodiversity,
species competition and disturbances |
multiple spatial scales |
Pictet and White 1985
Townsend 1989 |
| Four-Dimensional Nature
of Lotic Systems |
Longitudinal, lateral,
vertical, and temporal processes and patterns |
multiple spatial scales |
Ward 1989 |
| Habitat Template Concept -
Biological and Ecological Species Traits Concept |
K, r, and A selection
within spatial and temporal scales; resistance and resilience of
biocommunities; functional diversity |
multiple spatial scales |
Southwood 1977
Statzner et al. 1994
Townsend and Hildrew 1994 |
| Ecohydrology Concept |
Improved buffering
capacity of ecosystems against human impacts, ecological engineering and
ecosystem biotechnologies as management tools for sustainable water resources
use |
multiple spatial scales |
Zalewski et al. 1997 |
Figure. 9.1.
An hierarchically-nested
scheme for freshwater system assessment (defining the ecological status of
freshwaters controlled by multiple, scale-dependent environmental factors). An
analytical framework for integrated ecological monitoring is presented with
special emphasis on catchment assessment tools and data analysis procedures
| Integrated freshwater management,
defined as an
holistic, catchment-based approach that recognises the importance of processes
operating across a wide range of spatial and temporal scales, is applied at the
basin scale to protect and restore aquatic biological diversity. |
Many recent
catchment-based studies, taking advantage of GIS and multivariate statistics to
quantify landscape properties, have revealed the longitudinal, lateral, and
vertical influences of terrestrial ecosystems on the natural river environment.
Catchment characteristics, developed as a number of metrics describing
landscape structure in terms of e.g. the diversity and type of patches, are
very valuable for assessing ecological risk, ecosystem heterogeneity,
biological community structure ("biocommunities", and ecosystem responses to
management practices (Figure 9.2). Consequently, an assessment of ecological
integrity in aquatic systems, defined as the ability of an aquatic system to
maintain a balanced, integrated, and adaptive community of autochthonous
organisms (Karr 1981), should encompassed all of the major factors affecting
ecosystem stability (in terms of resistance and resilience).
| GIS
capabilities range from performing simple map measurements (e.g., length,
distance, and area) and creating map composites to quantifying spatial
patterns, position, and relationships (e.g., shape, diversity, proximity, and
connectivity). The ability to create polygons surrounding points, lines, or
other objects at a fixed distance has permitted researches to describe and
analyse edge effects and core areas, and to define ecotones. GIS technology
used conjunctively with simulation models has contributed to the development of
alternative scenarios of the future consequences of environmental phenomena and
in-stream processes. When GIS is used in concert with geostatistics, univariate
and/or multivariate statistics, and landscape models, complex relationships can
be elucidated and predicted. |
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