Page 140 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 3 1.2 1.2 Management context for river invertebrate
classification

Classification is a means of explaining environmental quality in very simple terms that can be understood by anyone.
We currently use a 5-point scale for this (Figure 3.2) and each class has a very simple description and is associated
with a colour so that water bodies of different quality can be mapped (Figure 3.3).

Figure 3.2
Correctly setting class boundaries is critical, helped by intercalibration (Peter Pollard for UK TAG)

Water chemistry has been classified for many years as the Biological status is defined in detail in the normative
core element of water quality assessment and management. definitions in Annex V of the Water Framework Directive.
More recently, we have recognised that environmental Identifying the metrics that we use to quantify biological
quality may be better reflected as ecosystem quality, which status and setting class boundaries correctly is critical
is defined by the biota (together with indicators of human for setting environmental quality objectives that fulfil
pathogens and physical parameters such as the amount of their intended role, and for assessing the effectiveness
water). The WFD therefore gives prominence to biological of measures to restore or maintain that quality. It is
parameters for classifying and reporting on the status of also critical for reporting the state of the environment.
our water bodies in relation to their environmental quality The concept of reference condition and its accurate
objectives. Biology is also used to define boundaries for determination for all water bodies is also critical, because
abiotic elements (including standards for physico-chemical it enables the classifications to be comparable between
elements, specific pollutants and flow). These remain vital different types of rivers that support different biotas.
for regulation, water quality improvement and abstraction This comparison is important locally, nationally and
management programmes to ensure that ecological internationally for identifying where we should target our
quality objectives are achieved and maintained. Biological limited resources for investigation and restoration.
monitoring and assessment is now key to determining
environmental quality and the following sections focus on
this with regard to river invertebrates.

140 | Freshwater Biology and Ecology Handbook
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