Shilland, EM; Clarke, G; Goodrich, S; (2017) River Clyde Environmental Change Network diatom analysis project final: report to SEPA. (ECRC Research Report 187 ). UCL Environmental Change Research Centre: London, UK.

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Abstract

This report provides details of work performed on the SEPA contract to ENSIS Ltd. involving the preparation and analysis of historic (September 1994 – August 2010) Environmental Change Network diatom samples from the River Clyde at the Tidal Weir. Diatoms were collected from the site by SEPA, forwarded to ENSIS Ltd and prepared for analysis following protocols described in the United Kingdom Environmental Change Network’s “Protocols for Standard Measurements at Freshwater Sites” (Sykes et al., 1999). Samples were taken at the site at various times of year and a full list of those that have been received by ENSIS is provided in Appendix 1. For this project, in order to minimise any inter-seasonal variability in the time-series, Kate Arnold from SEPA selected a subset of 16 summer samples for analysis, all collected between late July and early September. Approximately 400 diatom valves were counted per sample by Gina Clarke using a light microscope with phase contrast at 1000x magnification. Count data were recorded on a spreadsheet and transferred to ENSIS where they have been added to the ECN diatom database and have also been provided to SEPA. The diatom count data was run through the DARLEQII program (Kelly et al, 2011) in order to generate Trophic Diatom Index (TDI), Ecological Quality Ratio (EQR) and status class values (high, good, moderate, poor, bad) for each sample. Alkalinity values for the calculations were provided by SEPA for all samples except the earliest three in the timeseries, for which the average from all samples was used. Both TDI3 and TDI4 scores were calculated for all samples and the scores reported here. Table 1 is taken from the DARLEQII user guide (Kelly et al, 2011) and describes the output fields provided in the results section for the site below. Electronic copies of the full DARLEQII program output have been provided to SEPA.

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