Three hundred ways to assess Europe's surface waters: An almost complete overview of biological methods to implement the Water Framework Directive

Introduction Assessments of environmental conditions in rivers and streams with diatoms have a long history, which has resulted in the development of the two basic conceptual and analytical approaches used today. First, based on the work of Kolkwitz and Marsson (1908), autecological indices were developed to infer levels of pollution based on the species composition of assemblages and the ecological preferences and tolerances of taxa (e.g., Butcher, 1947; Fjerdingstad, 1950; Zelinka & Marvan, 1961; Lowe, 1974; Lange-Bertalot, 1979). Second, Patrick's early monitoring studies (Patrick, 1949; Patrick et al ., 1954; Patrick & Strawbridge, 1963) relied primarily on diatom diversity as a general indicator of river health (i.e., ecological integrity), because species composition of assemblages varied seasonally and species richness varied less. Thus, the concepts and tools for assessing ecosystem health and diagnosing causes of impairment in aquatic habitats, particularly rivers and streams, were established and developed between 50 and 100 years ago. The many advances in the use of diatoms and other algae for monitoring stream and river quality have been reviewed by Patrick (1973) and, more recently, by Stevenson and Lowe (1986), Round (1991), Whitton et al . (1991), Coste et al . (1991), Whitton and Kelly (1995), Rosen (1995), and Lowe and Pan (1996). There are three major objectives for this chapter. First, we emphasize the importance of designing environmental assessments so that many approaches are used and results are based on rigorous statistical testing of hypotheses. Second, we review the many characteristics of diatom assemblages that could be used in assessments and the methods and indices of assessment.

Assessing environmental conditions in rivers and streams with diatoms

Diatom metrics for monitoring eutrophication in rivers of the United States

1.
An index of riparian quality useful for the management of streams and rivers is presented. The purpose of the index is to provide managers with a simple method to evaluate riparian habitat quality. The index is easy to calculate and can be used together with any other index of water quality to assess the ecological status of streams and rivers. It may also be a useful tool for defining ‘high ecological status’ under the EC Water Framework Directive.

2.
The index, named QBR, is based on four components of riparian habitat: total riparian vegetation cover, cover structure, cover quality and channel alterations. It also takes into account differences in the geomorphology of the river from its headwaters to the lower reaches. These differences are measured in a simple, quantitative way. The index score varies between 0 and 100 points.

3.
The QBR index is calculated in the field through a two-sided A4 page form that may be completed in 10 min.

4.
The development of the QBR index included trials in four Mediterranean stream catchments in Catalonia (NE Spain). Seventy-two sampling sites were assessed and results were used to test the index.

5.
No taxonomic expertise is needed to apply the index, although some knowledge of local flora is required to differentiate between native and non-native tree species.

6.
These results show that the QBR index may be used despite regional differences in plant communities. The quality ranges obtained when the index is applied are not heavily influenced by observers at the same site.

7.
At present, the index is being used by different research teams and tested in a comparative study of 12 watersheds along the Mediterranean Spanish coast.

8.
It is expected that the QBR index may be adapted for use in other geographical areas in temperate and semi-arid zones without changes in the index rationale.



Copyright © 2002 John Wiley & Sons, Ltd.

A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index

Key-words: Bacillariophyta, biomonitoring, check-list, metric, river Diatoms are a very diverse group of microalgae that encompass about 100000 taxa. This makes an excellent bioindicator especially of rivers. The majority of biotic indices based on diatoms are constructed on species pollution-sensitivities. Nevertheless, recent studies showed the interest to use complementary metrics for biomonitoring: life-forms, cell-sizes and ecological guilds. Unfortunately, taxa memberships to such metrics are scattered in numerous floras and papers. Therefore, studies using such metrics often referred to grey literature or home-made checklists. The objective of this paper is to make available to the scientific community an important check-list of taxa frequently observed in European rivers with their memberships to these metrics. After defining these metrics, 1115 taxa were codified using Biofresh and Omnidia codes in an Excel file. Metrics memberships were then explored in a taxonomical framework. It clearly appears that metrics memberships are determined by taxonomy. Lifeforms and cell sizes taxa memberships and their study in the framework of evolutionary history of diatoms is a field that is worth studying for a better understanding of diatoms ecology. Such inputs should be beneficial for the future improvement of diatom-based monitoring tools.

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Life-forms, cell-sizes and ecological guilds of diatoms in European rivers

Many methods for using diatoms for routine monitoring of water quality have been developed in Europe and, in some countries, these are being used to enforce environmental legislation. In order to facilitate their wider use, particularly with respect to European Union legislation, steps are being taken to harmonize methodology. In this paper, the principles and practice of sampling are described in relation to the main habitat types encountered in Europe. Although details of methods and sampling programmes have to be tailored to particular circumstances and the overall objectives of the monitoring, a number of generalizations can be made. Where available, rocks and other hard surfaces are the preferred substrates and methods for sampling these are described. If such substrata are not available, then introduced ('artificial') substrata have many applications. Various types of introduced substrata can be used successfully, so long as some basic precautions are described. Other types of substrata such as macrophytes and macroalgae may also be useful under certain circumstances, although there is less consensus in the literature on the most appropriate methods, and of the validity of comparisons between indices computed from epiphytic and epilithic communities. When designing surveys, it is recommended that as far as possible, extremes of non-water quality factors (e.g. shade, current speed, etc) are avoided, unless these are characteristic of the system under investigation. Detailed guidelines for sampling epilithon are described. Along with the recommendations for sampling other substrata, it is hoped that these provide a framework that can be adapted to most river types in Europe.

A. Cazaubon

Papers

Recommendations for the routine sampling of diatoms for water quality assessments in Europe