Page 266 - Freshwater-Biology-and-Ecology-Handbook

Conclusion

This chapter reviews some of the key sample and As previously stated, it is important to differentiate the
data analysis methods used for investigations and to data sets from these monitoring activities, as the data from
better understand the complex interactions between investigative monitoring may bias classification toward a
environmental factors and invertebrate communities. Some specific short-term event, such as a transitory pollution
may be impacted by natural ecosystem change and others incident. Care must be taken in sample programme design
due to anthropogenic activity, including pollution, water to optimise these complementary activities and yet ensure
abstraction, flood alleviation activity and climate change. high quality information for decision making and reporting.

Biotic indices are numerical values that relate the
As a reminder, investigative monitoring is usefully presence of taxa to environmental pressures. Their role
defined as follows by the EU WFD: is to simplify complex biological data so that ecologists
can explain their results to environmental managers
To identify the causes of poor environmental quality who may have little knowledge of ecology.
(diagnosis) and their timing and source so that
an appropriate programme of measures can be Although their format is intentionally very simple (usually
implemented to restore quality. a single number or letter), biotic indices are actually very
complex, and most do not behave as parameters on a
continuous scale of equal intervals. Biotic indices should
Investigative monitoring is undertaken in close association not be used as a basis for statistical analysis.
with surveillance monitoring which assesses long-term
changes in the environment due to natural and widespread Indexes are easily misused and can be misleading. Users
anthropogenic activity. It is the basis for formal classification should be wary of using biotic indices, particularly without
and reporting of water quality and drives the infrastructure understanding the extent of the data from which they were
investment programmes. Operational monitoring is used derived, or the specific uses for which the indexes are
to confirm the status of water bodies at risk from known designed.
pressures and to assess the efficacy of improvement
programmes.

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