Lakes and Watercourses

TABLE 41.
CURRENT CONDITIONS: bottom fauna index, profundal zone
in lakes
Class Description BQI-index O/C-index*
1 Very high/very low index > 4 ≤ 0.5
2 High/low index 3.0 – 4.0 0.5 – 4.7
3 Moderately high/low index 2.0 – 3.0 4.7 – 8.9
4 Low/high index 1.0 – 2.0 8.9 – 13
5 Very low/very high index ≤ 1.0 > 13
* Adjusted for sampling depth (see Appendix 4)
Assessment of deviation from reference values
TABLE 42.
DEVIATION from reference value: bottom fauna index, lakes and
watercourses
Class Description Recorded value/reference value
O/C index Other index
1 No or slight deviation < 0.3 > 0.9
2 Moderate deviation 0.3 – 0.6 0.8 – 0.9
3 Significant deviation 0.6 – 0.8 0.6 – 0.8
4 Large deviation 0.8 – 0.9 0.3 – 0.6
5 Very large deviation > 0.9 < 0.3
This classification is based on the EC white paper prior to the framework
directive on water (Nixon et al., 1996), which describes each class as
follows (with some modifications).
Class 1. No or insignificant effects of disturbance. No or only
insignificant anthropogenic impact on communities of organisms or their
habitat. The macro invertebrate community resembles that normally
occurring in the type of habitat under undisturbed conditions.
Class 2. Moderate effects of disturbance. The benthic fauna shows
signs of disturbance but only deviates slightly from its undisturbed state.
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