The degree of impact that these four stresses are having upon specific locations within the catchment can be identified through analysis of EA invertebrate data sets. The resulting mapping can be used to identify and target areas for further study or for remediation action. Further sampling can be undertaken to look into species-level data to provide a finer level of detail on the impacts of the stresses within the catchment.

The technique takes historic EA invertebrate sampling data and analyses the community structure for each site against four biometric indices: LIFE (low-flow impacts), PSI (fine sediment), Saprobic (organic pollution) and TRPI (total reactive phosphorus index).

Each of these environmental impacts induces characteristic reactions within the invertebrate community, such that it can be scored on any occasion for degree of impact on each index. Each site is colour-coded for each index, where blue is clean, through to red – heavily impacted.

The arrows in each coloured box indicate, over the available run of data, whether the impact is getting worse (up arrow), better (down arrow) or staying the same (level arrow).
Under licence, anyone can access the historic EA sampling data. WCSRT employed Dr Nick Everall of Aquascience Consulting Ltd to assess the invertebrate community data and compute the relevant biometric scores.