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

Aim To study large-scale patterns of benthic diatom assemblages in rivers, to assess the relative importance of environmental and geographical factors affecting their composition, and to evaluate the implications of these patterns for the use of diatoms as indicators of water quality, particularly nutrient enrichment. Location The United States Geological Survey (USGS) National Water Quality Assessment (NAWQA) Programme data set covers the conterminous United States. Methods We employed gradient analysis to understand the floristic structure of the data set and to discover major ecological gradients underlying variation in species composition at different spatial scales (entire US, Omernik Level 1 and Level 2 ecoregions). We used variance partitioning to separate the effect of environmental and spatial characteristics. Results At the national scale, three major ecological gradients were evident. The first was a complex ‘downstream’ gradient from fast-flowing, mostly oligotrophic, highland rivers to predominantly eutrophic rivers of high- and low-elevation plains. The second was a gradient integrating water mineral content and pH, which separated the soft and often more acidic waters of the humid eastern part of US from the alkaline waters of arid western regions. The third obvious gradient was related to latitudinal and altitudinal variation of temperature. Up to one-third of the total explainable variation in species data was attributed solely to geographical factors not correlated with measured environmental characteristics. We present several examples of species with complex patterns of spatial distribution. Main conclusions Although environment consistently plays the most important role in structuring diatom assemblages in rivers, spatial factors also explain some variation in diatom distribution, especially at the continental scale. Most of the species that are confined to limited geographical areas are not yet described and await future taxonomic work. We show that selection of species which could serve as indicators of nutrient enrichment in US rivers is not a straightforward procedure. The existence of complex environmental gradients, and still poorly understood spatial patterns of species distribution, precludes attempts to develop uniform diatom-based metrics that would be applicable everywhere in the US. We advocate the development and calibration of metrics based on data sets collected from more limited geographical areas, and that include sites having relatively narrow ranges of environmental characteristics other than that which the metrics are designed to indicate.

Benthic diatoms in USA rivers: distributions along spatial and environmental gradients

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

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.

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

Biological and chemical data were processed to estimate trophic stage and degree of pollution in several streams and rivers in southern Poland. The majority were eutrophic and some of them heavily polluted; only a few were oligo-mesotrophic. The differences in the water quality of the rivers were reflected by different types of diatom community and also by the values for some diatom indices, which were calculated using the latest version of the 'Omnidia' database software. Except for the Sladecek's index, all diatom indices correlated significantly with organic load (COD), oxygen concentration, conductivity and most of the measured ions. Some indices showed a significant negative correlation with trophic level (expressed by NH4-N and PO4-P). In general, IPS (Specific Pollution Sensitivity Index) and GDI (Generic Diatom Index) indices gave the best results. Among the investigated diatom communities, only a few taxa indicated oligo-mesotrophy and oligo-β-mesosaprobity. Most of the sites were characterised by a greater relative contribution of eutraphent and tolerant ones as well as α-mesosaprobic and polysaprobic diatoms. This study suggests that the structure of benthic diatom communities and diatom indices, especially GDI, can be applied for monitoring rivers in Poland.

Use of benthic diatom communities to evaluate water quality in rivers of southern Poland

The freshwater red algal genus Batrachospermum has been shown to be paraphyletic since the first molecular studies of the Batrachospermales. Previous research, along with this study, provides strong support for the clade Batrachospermum section Helminthoidea. This study has found that heterocortication, the presence of both cylindrical and bulbous cells on the main axis, is an underlying synapomorphy of this clade. Based on support from DNA sequences of the rbcL gene, the COI barcode region and the rDNA ITS 1 and 2, along with morphological studies, the new genus Sheathia is proposed. Seven heterocorticate species were recognized from the molecular clades. Sheathia boryana and S. exigua sp. nov. appear to be restricted to Europe, whereas S. confusa occurs in Europe and New Zealand. Sheathia involuta is widespread in the USA and reported for the first time from Europe. Sheathia americana sp. nov., has been collected in the USA and Canada, and S. heterocortica and S. grandis sp. nov. have been collected only in the USA. Sheathia confusa and S. grandis can be distinguished based on morphological characters, whereas DNA sequence data are required to conclusively distinguish the other species. Sheathia fluitans and S. carpoinvolucra also are placed within this genus based on the presence of heterocortication. These data also hint at greater diversity among non-heterocorticate Sheathia than is recognized by the single species name S. arcuata.

Molecular and morphological evidence for Sheathia gen. nov. (Batrachospermales, Rhodophyta) and three new species

A comparison has been made of the species composition of diatom communities developing in acidic Polish mountain streams which flow over calcium-poor substrates: sandstones in the Silesian Beskid (section of the Western Carpathians), the Świetokrzyskie Mts, and over granite in the Karkonosze range (in the Sudetic Mts). The number of taxa and diversity of the diatom assemblages decreased along a decreasing pH gradient. The correlation between pH and the number of taxa was positive and significant (r2 = 0.69, p < 0.005). A small number of species (< 20) and low diversity were found in the communities developing in strongly acidic streams such as in the Świetokrzyskie Mts with pH 4.1–5.2, and in the Silesian Beskid with pH 3.5–4.0. In the stream of the Karkonosze Mts, with pH 5.2–6.0, the communities were characterized by their greater number of species and higher diversity.

Diatom communities of acidic mountain streams in Poland

Macroscopic red algae were sampled simultaneously with diatom sampling from 60 locations in central Finnish rivers and at some rivers in south coast rivers in the summers 1986, 1993 and 1994. In those samples 17 red algal taxa from 5 genera (Audouinella (3). Batrachospermum (7). Lemanea (4), Sirodotia (2) and Tuomeya (1)) were identified. Some of these taxa were new to Finland and two were new for Europe.

Janina Kwandrans

Papers

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

Use of benthic diatom communities to evaluate water quality in rivers of southern Poland

Molecular and morphological evidence for Sheathia gen. nov. (Batrachospermales, Rhodophyta) and three new species

Diatom communities of acidic mountain streams in Poland

Distribution and ecology of freshwater red algae (Rhodophyta) in some central Finnish rivers