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Taxonomy poses many problems because it is constantly being refined, with our understanding being developed, and so it
constantly changes. RIVPACS follows the nomenclature of the revised Furse-Maitland coded checklist, but it also includes
other coding systems including the National Biodiversity Network codes. The taxonomy in RICT was reviewed in 2007, so
presumably follows the 2007 update of the revised Furse-Maitland coded checklist. (33)

A description of the taxonomy adopted in RICT is provided in the following report which can be downloaded from the Reports
page of the RICT2 website (34) https://www.fba.org.uk/rivpacs-and-rict/rivpacs-rict-resources

12.6 Enumeration
Table 2.8
Numerical abundances are either counted or estimated. RIVPACS abundance categories
Numerical abundances allow much more flexibility in
subsequent data analysis than the RIVPACS logarithmic Abundance category Numerical abundance
abundance categories (Table 2.8). For standard RIVPACS 1 1 – 9
samples, counting taxa present in low numbers (up to 50
individuals) and estimating the rest is recommended. There 2 10 – 99
are a variety of methods for doing this, based on counting 3 100 – 999
a proportion in each sorting tray and multiplying up by
proportion. 4 1000–9999

Until about the year 2000, the environmental protection 5 >9999
agencies in the UK only recorded RIVPACS abundance
categories. Numerical abundance records facilitate many
more types of analysis, including calculation of biotic indices
using different abundance scales, and diversity indices.

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