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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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