Lakes and Watercourses

APPENDIX 2
(6) O/C index (Wiederholm, 1980) is calculated as:
the density of oligochaetes divided by the density of oligochaetes and
sediment-living chironomids (not including non-sediment-living species
such as Procladius sp.), expressed as a percentage. Values are depthcorrected
by dividing the ratio obtained above by the sampling depth.
References
Armitage, P.D., Moss, D., Wright, J.F. & Furse, M.T. (1983): The performance of a
new biological water quality score system based on macroinvertebrates over a
wide range of unpolluted running-waters. – Water Research 17:333-347.
Henrikson, L. & Medin, M. (1986): Biologisk bedömning av försurningspåverkan på
Lelångens tillflöden och grundområden 1986 (”Biological assessment of the impact
of acidification on tributaries and shallow areas of the river Lelången, 1986”). –
Aquaekologerna, Report submitted to Älvsborg County Administrative Board.
Shannon, D.E. (1948): A mathematical theory of communication. Bell System
Technological Journal 37:379–423.
Skriver, J., Friberg, N. & Kirkegaard, J. (to press): Biological assessment of
watercourse quality in Denmark: Introduction of the Danish Stream Fauna Index
(DSFI) as the official biomonitoring method. – Verhandlung der Internationalen
Vereinigung für Theoretische und Angewandte Limnologie 27.
Wiederholm, T. (1980): Use of benthos in lake monitoring. – Journal of the Water
Pollution Control Federation 52:537-547.
99