The first studies of diatoms and river pollution were carried out 60 years ago, and the suitability of these micro-algae as bioassessment indicators for monitoring river quality was quickly demonstrated. The objective of this review is to describe the state of the art of the study of diatoms and river pollution between 1999 and 2009. The objective was to group the publications homogeneously according to subject and to indicate which subjects never overlap. To this end a lexical analysis was conducted on the abstract structure of these publications and seven K-means clusters were defined. Most of the items in this area were found to have been published in Hydrobiologia. One group (group 6) comprises publications about a discipline (ecotoxicology); several others group publications on the basis of the same approaches, for example species (group 3), basin (group 7), or spatial approaches (group 2). Other publications are brought together because the studies used a common method of using data, namely predictive models (group 1) or biotic indices (group 4). One group of publications was of studies performed in the same area—South Africa (group 5). Several remarks can be made. First, ecotoxicological studies are mostly experimental and restricted to small study areas. To answer society’s demand for new assessment tools for micropollutant assessment, the next step would be to have more in-situ tests on larger spatial scales. Second, diatom biomonitoring uses the word “species” extensively, because this is the basis for establishing the lists of flora which are used extensively in such subject areas. Species is closely related to taxonomy; nevertheless this discipline is very rarely addressed in the papers. Third, phylogeny is never addressed in the publications. This is significant because phylogenetic studies for freshwater macroinvertebrates enable appropriate definition of taxonomic aggregations that can be used as accurate indicators of particular environmental stressors.

Recent views on river pollution and diatoms

The inclusion of diatoms into the current suite of biomonitoring tools in use in South Africa, as well as the use of European and other diatom indices in South Africa, and in particular the Crocodile and West Marico water management area, is discussed. The indices, when compared to chemical analyses, proved useful in providing an indication of the quality of the investigated waters. Several widely distributed diatom species were shown to have similar ecological tolerances in South Africa when compared to Europe. Although most of the diatoms encountered in the study were cosmopolitan, several possibly endemic species were recorded. The occurrence of endemic species, not included in existing diatom indices may lead to miscalculations of diatom indices. It is concluded that although diatom indices developed in Europe and elsewhere are useful at the present to indicate water quality, a diatom index unique to South Africa including endemic species will have to be formulated.

/pdf/can-diatom-based-pollution-indices-be-used-for-biomonitoring-zdx3ln9pcd.pdf

Can diatom-based pollution indices be used for biomonitoring in South Africa? A case study of the Crocodile West and Marico water management area

Use of diatom life-forms and ecological guilds to assess pesticide contamination in rivers: Lotic mesocosm approaches

The applicability of some diatom methods to quality assessment of differenttypes of Finnish rivers was compared using dominant taxa of diatomcommunities and nutrient level estimations using Trophic Diatom Index(TDI) and a new Phosphorus Diatom Equation (PDE) [Tot. Pcalc (μg l-1) = 39 – 0.278 ol-% – 0.117 olme-% – 0.346me-% – 0.006 meeu-% + 1.193 eu-%; n = 97; r2 = 0.742;SE = 17.4]. The overall quality estimations were done by Index ofPollution Sensitivity (IPS) and by Generic Diatom Index (GDI); limit valuesfor quality classes are proposed.

Ecological status of some Finnish rivers evaluated using benthic diatom communities

The Keelung River (Taiwan) is heavily polluted by domestic, industrial and agricultural wastes. Water quality, particularly in ammonium, nitrite, silicate, and turbidity, negatively correlated with dissolved oxygen. A generic index (GI) – the ratio of abundance of Achnanthes, Cocconeis and Cymbella, to that of Cyclotella, Melosira and Nitzschia – was used to measure changes the diatom assemblages. GI values correlated well the saprobic index, diatom assemblage index, composite river water quality index and species richness of insects. It correlated less well with the trophic diatom index and distribution of fish in the river, suggesting that GI was more indicative of organic pollution than of eutrophication. Data from two of other Taiwanese rivers were used to test the applicability of GI. As in the Keelung River, GI correlated well with the saprobity index, diatom assemblage index and river water quality index.

/pdf/a-generic-index-of-diatom-assemblages-as-bioindicator-of-15ifuu9zzi.pdf

A. Houki

Papers

Numerical estimation to organic pollution of flowing water by using the epilithic diatom assemblage ----- diatom assemblage index ( DAIpo ) ----