Lakes and Watercourses

The genera in question and their trophic ranking scores and sensitivity
to pollution are listed in the method description in the EPA Environmental
Monitoring Handbook; indices can be calculated using the
Omnidia software.
The class boundaries essentially reflect the state of the watercourse as
follows:
Class 1. Highly oligotrophic to oligotrophic state and no or insignificant
pollution.
Class 2. Oligotrophic to eutrophic state and/or slight pollution.
Class 3. Eutrophic to highly eutrophic state and/or obvious pollution.
Class 4. Severe pollution.
Class 5. Very severe pollution.
This classification is based on European studies and have been
adapted to Swedish conditions in terms of pollution levels and algal
occurrence. It has been tested on limited Swedish data from various
ecotypes.
Assessment of deviation from reference values
There is no background data from which to determine reference values
and therefore no proposed assessment of deviation is described here.
Comments
Experience in Sweden of water quality assessment using diatoms is
limited and the model criteria in this chapter are therefore largely based
on experience in other countries. Class boundaries and other aspects may
be adjusted as more is learnt about Swedish conditions.
The assessment must be based on samples taken and analyses made in
accordance with the Swedish EPA Environmental Monitoring Handbook
and analyses made in accordance with the Swedish standard.
References
Jarlman, A. & Bengtsson, R. (1999): Påväxt – kiselalger (”Periphyton - diatoms”). –
From: T. Wiederholm (Ed.). Bedömningsgrunder för miljökvalitet – Sjöar och vattendrag.
Bakgrundsrapport 2 - Biologiska parametrar (”Environmental Quality Criteria
– Lakes and Watercourses. Background report 2 – Biological parameters”).
Swedish EPA Report 4921.
Lecointe, C., Coste, M. & Prygiel, J. (1993): ”Omnidia”: software for taxonomy,
calculation of diatom indices and inventories management. – Hydrobiologia
269/270:509-513.
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