Page 66 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 1 5.6 Table 1.12 Element Metric Software Tool
Current official UK biological status classifications for WFD (2nd cycle), from Defra 2014.

Water body
Category

Alien invasive
All
Table in Defra standards
River
Mean Trophic Rank (MTR)
River LEAFPACS 2
Macrophytes
River Phytobenthos Trophic Diatom Index v4 (TDI 4) River DARLEQ 2
Number of Walley Hawkes Paisley Trigg-scoring River Invertebrate
River Invertebrates
taxa (WHPT Ntaxa) Classification Tool (RICT)
Average Walley Hawkes Paisley Trigg score
River Invertebrates RICT
per taxon (WHPT ASPT)
WFD species-level Acid Water Indicator
River Invertebrates
Community (WFD AWICsp)
River Fish FCS2

Lake Phytoplankton PLUTO
Phytobenthos TDLI 2 Lake DARLEQ2
Macrophytes Lake LEAFPACS2

Invertebrates Chironomid Pupal Exuviae Technique (CPET)
LAMM

The overall biological status is the status class indicated efficient use of resources. Where more than one element is
by whichever biological quality element indicates the sensitive to a pressure, eg all are sensitive to eutrophication,
worst status, following the ‘one out, all out’ principle. expert opinion should be employed to choose the most
Certain invasive non-native species also contribute to the sensitive elements for the category of water concerned.
classification, but only in so much that they prevent sites
where they exist from being classified as high status. The use of multiple metrics can improve confidence in
the final classification. For example, when assessing
A number of different parameters (eg the balance of phytoplankton, biomass is an important metric because it
different groups of species, the number of different determines the overall amount of phytoplankton which in
species, the overall abundance of species, etc) may be turn influences light penetration and oxygen concentration
used to estimate the status of a quality element. These in a water body. Taxonomic composition is also an
parameters are quantified in various metrics or biotic important metric of phytoplankton because it shows when
indices. Different metrics indicate the impact of different highly undesirable species (such as cyanobacteria and
pressures (eg the effects of pollution or the effects of other opportunistic taxa) are starting to dominate the
morphological alterations) on the element. Results for phytoplankton community and when taxa indicative of
different metrics may be combined to give a representative particular environmental pressures are prevalent.
picture of the impact of a particular type of pressure (or
range of pressures) on the quality element. Multi-metrics The tools developed for classification should continue to be
may be appropriate where none of the metrics on their refined to reflect newly emerging environmental pressures
own give a sufficiently reliable indication that the quality and to improve the accuracy of status assessment in order
element has been adversely impacted as a result of human to improve the certainty that programmes of measures are
activities. Within a quality element, different metrics are implemented where they are needed. This development
combined in the most appropriate way, most commonly work should take account of new data collected through
either ‘one out, all out’, or an average. An overview of the UK monitoring programmes, together with improvements in
classifications and tools is given in Table 1.12. scientific understanding on causes and effects. New or
modified tools should also be developed where the existing
Operational monitoring only needs to include the quality tools are currently unable to properly reflect the impact of
elements most sensitive to the pressures affecting the status particular pressures on the water environment.
of the water body. Table 1.13 provides an expert judgement
view (from UK Technical Advisory Group) as to which Details of specific aquatic invertebrate metrics are dealt
elements are most appropriate for specific pressures. The with in detail in Chapter 3.
table provides a means of focusing monitoring effort to aid

66 | Freshwater Biology and Ecology Handbook
–