Page 42 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 1 2.5 2.5 The use of ecological As outlined in the WFD timetable, there is a 6-yearly cycle
monitoring information –
in WFD-based water management. Water bodies are
assessed every 6 years. If a water body fails to meet the
environmental goals, the cause must be determined, and
links to pressures
measures must be taken to improve the environmental
status. The reasons for failure of biological status are
which pressure is causing a biological failure needs to be
In the UK, the Department for Environment, Food and Rural
addressed.
Affairs (Defra) issued guidance on how biological failures not always clear, so the question of how to determine
identified by monitoring programmes can be attributed to
environmental pressures (land use, pollution, hydrology, The text which follows is from the above-mentioned
etc). See Defra (2011) How we determine which pressure Defra document and is written with reference to Figure 1.6
is causing a biological failure in the context of the Water which gives an overview of the current procedure used to
Framework Directive. (14) determine which pressure is causing a biological failure.

1. START – No
Biological STOP
failure?
Yes
Professional knowledge of Assessment of existing
response of biology to pressures in water body &
pressures wider catchment

Existing biological data and
Diagnostic methods & tools
its trends

CONSIDER ACTION
Yes

2. Can we infer the Yes 3. Is the level of evidence
linking failure and cause
cause of failure?
sufficient to justify action?
No No
No 4. Is current data adequate to Yes 6. Can’t infer what causes
5. Gather more data: apply diagnostic toolkit and the problem with current
investigative monitoring professional judgement? evidence, then…

7. Gather and assess more extensive
data on pressures and biology (eg Either
data on other biological elements;
data from other parts of catchment)
to infer a likely cause

8. Investigate most likely cause first Or
based on local knowledge and
professional judgement

Either
9. Intensifying monitoring focusing on by
biological elements most likely to be
affected by likely cause

10. Applying a measure as an experiment Or by
(adaptive management) Figure 1.6
(Expert support on experimental design)
An overview of the current practice used to determine
which pressure is causing a biological failure. Defra 2011 (14)

42 | Freshwater Biology and Ecology Handbook
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