Page 264 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 5 3.2.7 3.2.7 RPDS (River Pressure Diagnostic System)

This is one of the few systems or tools described in this
The current version of RPDS (Version 3.5) holds river
invertebrate data from more than 13,000 sites across
handbook that is not currently available outside the
England, Scotland and Wales, and data from 86,000
regulatory agencies, although it is hoped that it can be
samples collected between 1995 and 2004, identified to
reprogrammed into a web application to make it more
BMWP-scoring families (RIVPACS Taxon Level 1).
widely available. It is one of the few tools that assumes that
macroinvertebrate communities respond to combinations of
environmental pressures, in contrast to most biotic indices
which aim to identify the impacts of individual pressures. These are matched to 13 environmental parameters
including RIVPACS prediction variables, the concentrations
of 42 chemicals from 5,600 chemical monitoring sites and
expressed as 3-year percentiles (as used for chemical
RPDS – River Pressure standards), flow data (whether the flows were higher or
lower than average), information from local ecologists on
Diagnostic System the environmental stresses that they think or know affect
the sites (perceived stresses), and river invertebrate status
A system for diagnosing environmental pressures information. Recent data sets for RPDS include more
that assumes that macroinvertebrate communities biological and chemical data from 1995–2012, land cover,
respond to combinations of pressures. This is in geology, and morphological information from River Habitat
contrast to most biotic indices which aim to identify Surveys (RHS).
the impacts of individual pressures.
The RPDS display can also help users characterise the
environmental conditions at their site by displaying the
For River Basin Management under the Water Framework average values of any of the environmental parameters or
Directive, we must not only assess the status of ecological abundance of any macroinvertebrate family as colours on
quality, for which we use the classification described in the circles representing each community type (Figure 5.16).
Chapter 3, but we must also discover the reasons for failure Diagnoses can be made for many sites together, for which
in order to identify an effective programme of measures to RPDS produces results in a spreadsheet showing pressures
restore quality, which is the aim of investigations described in in order of deviation from global average condition, to
this chapter. highlight environmental parameters with particularly high or
low values. Using RPDS, it becomes clear that pressures do
The River Pressure Diagnostic System (RPDS, previously not occur randomly but in characteristic combinations and
referred to as River Pollution Diagnostic System) helps us that different invertebrate communities are associated with
diagnose which environmental pressures are influencing these combinations of pressures. It prevents ecologists from
the biological quality. It is particularly useful when we don’t falling into the trap of assuming that a particular pressure is
know what may be causing poor quality, or to give objective confirmed as the cause of poor invertebrate quality when an
evidence to support our own diagnosis – a second opinion. index sensitive to that pressure shows a response.

RPDS mimics one of the main thought processes that RPDS includes several other tools, maps and reports to
ecologists use to interpret biological survey data: pattern help users interpret their results. Comprehensive online
recognition. RPDS recognises patterns of composition and help is available on the current system, as well as detailed
abundance and associates them with the environmental descriptions of each of the taxonomic, ecological and
conditions at other sites showing similar patterns. To environmental parameters included in the system.
use RPDS, you input results from a standard (RIVPACS)
river invertebrate sample (a list of BMWP families and The data sets compiled for RPDS with data from matched
their abundances, together with RIVPACS environmental biological, chemical and RHS monitoring sites are useful in
predictors). RPDS classifies your biological sample with their own right – for example, they have been used to help set
the group of samples in its database that has the most more realistic environmental standards for chemicals.
similar composition. The average values of environmental
parameters recorded at those sites provides a diagnosis of Two useful references are Paisley et al. (2011), (127) and
the environmental conditions that are affecting invertebrates Trigg (2020). (128)
at your site. Whereas RIVPACS GB recognises 64 natural
types of invertebrate communities, RPDS recognises about
250, covering not only natural types but those associated
with different combinations of environmental pressures.

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