Page 82 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 2 2 2

DESIGN OF INVERTEBRATE

MONITORING PROGRAMMES

Most biological monitoring in the UK is based on the Because they rely on invertebrate status classification,
RIVPACS sampling and laboratory methods described surveillance and operational monitoring programmes, and
here. It is provided as an example of a national invertebrate some investigative monitoring programmes, involve the
monitoring method. Similar biological monitoring methods collection of samples in spring and autumn (Section 4).
are used across the EU and in many other countries. The New monitoring sites are also surveyed in summer, but only
principles are the same and can be adapted to suit the for the collection of environmental data (Section 7.6) so that
various aquatic habitats across the world. the annual average values can be calculated for RIVPACS.

The requirements for investigative, operational and The location of sampling sites may be different for each
surveillance monitoring are different (see Box above), so type of monitoring. Sites that are representative of water
they should be planned as separate activities. Monitoring bodies are selected for local surveillance, operational and
should be optimised to ensure efficient sampling and data some investigative monitoring, but must always comply with
collection, so samples may be used for more than one the more general requirements for RIVPACS (Section 5).
purpose, but data must be marked to identify each driver Operational and investigative monitoring sites are usually
to prevent bias in classification. However, opportunities located at the downstream ends of water bodies to detect
to collect samples for multiple purposes without biasing upstream pressures. Investigative or operational monitoring
results are limited. For example, high frequency sampling to monitor major discharges or abstractions usually involve
during an investigative monitoring exercise in response both downstream and matching upstream control sites.
to a short-term pollution event can significantly bias However, in surveillance assessments, this bias can lead
surveillance or operational monitoring results and result in to an under-representation of smaller streams and the
an unrepresentative classification. environmental pressures that they face.

Example of potential sampling Example of potential sampling

bias – avoid poor quality bias bias – under-representation of
small water bodies
In 2020, the Environment Agency in England established
a completely new River Surveillance Network, sampling The Environment Agency 2021 River Surveillance
for which started in 2021. It did this because its Network in England includes small streams and streams
monitoring was increasingly targeted at investigative that are intermittent (ie do not always flow), but not
and operational monitoring to help its management obviously artificial drainage ditches. These are important
activities. The resulting risk-based programme was habitats that are usually beyond current monitoring. It
inevitably biased to water bodies where there was poor also includes sites influenced by local pressures, such as
quality. This bias led the organisation to conclude that it bridges that are avoided when locating sites to represent
needed a completely separate and unbiased monitoring whole water bodies. This corrects the potential bias
network to assess overall quality and changes in quality identified above. It still excludes spring zones which
at a national and regional scale.
require different sampling methods.

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