Trewithen Dairy Aquatic Macro-Invertebrate Report
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Rain-Charm House Kyl Cober Parc Stoke Climsland Callington Plymouth PL17 8PH TREWITHEN DAIRY, LOSTWITHIEL Reference TE 676/18/01 Macro-invertebrate Survey December 2018 Client Trewithen Dairy Report reference TE 676/18/01 Surveyor (and licence Lee Knight BSc MCIEEM number if applicable) Date of survey 29 October 2018 Author Lee Knight BSc MCIEEM Authorised by Dr Bruce Forrest Westcountry Rivers Ltd is the commercial trading subsidiary of the Westcountry Rivers Trust (Charity № 1135007 Company № 06545646). All profits are covenanted to the Trust. Registered Office: Rain-Charm House, Kyl Cober Parc, Stoke Climsland, Callington, Cornwall PL17 8PH UK Registered in England No: 3090310 VAT Registration No: 115 1369 41 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey SUMMARY Westcountry Rivers Ltd was commissioned by Trewithen Dairy to conduct an aquatic macro-invertebrate survey in accordance with the conditions of their Abstraction Licence (Serial No: 15/48/018/G/017R01). Surveys were undertaken on 29 October 2018 at seven monitoring sites determined within the abstraction licence, following the procedures set out in the Environment Agency’s Operational Instruction 018_08: Freshwater macro-invertebrate sampling in rivers. These surveys supplemented previous surveys undertaken of the monitoring sites in 2014, 2015, 2016 and 2017. Samples were analysed to family taxonomic level in accordance with the Environment Agency’s Operational Instruction 024-08: Freshwater macro- invertebrate analysis of riverine samples. The data were analysed using the River Invertebrate Classification Tool (RICT) software, which incorporates version IV of the River Invertebrate Prediction and Classification System (RIVPACS), and the following indices were calculated: • Walley Hawkes Paisley Trigg (WHPT) indices (WHPT score, N-TAXA (number of scoring taxa) and ASPT (Average Score Per Taxon) • Biological Monitoring Working Party (BMWP) indices (BMWP score, N-TAXA and ASPT) • Lotic-Invertebrate Index for Flow Evaluation (LIFE). Results showed that all the sites continued to harbour invertebrate assemblages of exceptional diversity for such small watercourses, similar in composition to those recorded during previous surveys. All seven of the sites exhibited high BMWP and WHPT indices and were classified by RICT as being of high biological status under the Water Framework Directive (WFD) classification used by the Environment Agency and other UK environmental regulatory agencies to assess the environmental health of watercourses. The LIFE scores indicated that the invertebrate communities present are adapted to fast flowing conditions and the scores showed no significant reduction in comparison to previous surveys. LIFE Ecological Quality Indices (EQIs), calculated using values predicted by RICT, were close to or above unity, indicating no discernible impact on the invertebrate assemblages by the current levels of abstraction. TE 676/18/01 December 2018 Page 3 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey Table of Contents 1 INTRODUCTION ...................................................................................... 5 1.1 Background ................................................................................................................. 5 1.2 Site descriptions ......................................................................................................... 6 2 METHODS ............................................................................................... 9 2.1 Survey .......................................................................................................................... 9 2.2 Identification and Analysis ........................................................................................ 9 3 RESULTS AND DISCUSSION ............................................................... 11 4 CONCLUSION ....................................................................................... 18 References Appendices TE 676/18/01 December 2018 Page 4 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey Trewithen Dairy, Lostwithiel - Macro-invertebrate Survey 1 Introduction 1.1 Background Trewithen Dairy is currently authorised to abstract water from six boreholes according to the conditions set out in the Abstraction Licence (Serial No: 15/48/018/G/017/R02). The Dairy is located at Greymare Farm, Lostwithiel PL22 0LW. The location of the boreholes is shown in Figure 1 and together they achieve a maximum abstraction of 150m3/day. Under the terms of the Abstraction Licence, Trewithen Dairy is required to monitor the impacts of the abstraction on the surrounding streams. Seven monitoring sites on streams within the River Fowey catchment were identified by the Environment Agency (Figure 2). An initial baseline survey of aquatic invertebrates was undertaken in May 2014 and subsequently repeated in October 2014, April 2015, September 2016 and October 2017 (URS, 2015; Westcountry Rivers Ltd, 20171; 20172). The aim of monitoring the aquatic invertebrate communities was to confirm that the current levels of abstraction are having ‘no discernible impact’ on the ecology of the watercourses. Figure 1. Borehole locations Trewithen Dairy TE 676/18/01 December 2018 Page 5 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey 1.2 Site descriptions The seven monitoring sites are located within the catchments of four watercourses: Bofarnal Stream (site B1 and a minor tributary, B2), Drift Stream (D1), Greymare Stream (G1) and Hollycoombe Stream (H1, H3 and the Penadlake Farm tributary, H2) (Table 1 and Plate 1). These are all small streams located in semi-natural broadleaved woodland. The monitoring sites were in unmodified channels with earth banks and large amounts of riparian vegetation overhanging the streams. As a result, moderate amounts of leaf litter were present in-channel. Table 1. Location of monitoring sites Watercourse Reference Grid reference Description number Bofarnal TD-B1 SX 11748 62919 Immediately upstream cattle drink fence, Stream 35m downstream footbridge, downstream pond TD-B2 SX 12109 63174 By SE bend in forestry track, 10m downstream posts over stream, upstream black cable crossing stream Drift Stream TD-D1 SX 13051 64953 37m Upstream culvert under railway, 30m upstream track bridge, by large beech on LHB Greymare TD-G1 SX 11548 64453 On westerly bend in stream, close to Stream forestry track, in open section between entrenched, overgrown reaches Hollycoombe TD-H1 SX 13594 64946 7m upstream culvert at Penadlake Stream viaduct, Immediately upstream mid- channel bar and tributary on RHB TD-H2 SX 13721 64125 2m upstream track bridge TD-H3 SX 13569 64217 Immediately downstream sharp bend in stream by road, opposite Higher Hollycombe Farm drive. TE 676/18/01 December 2018 Page 6 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey Figure 2. Location of sampling sites TE 676/18/01 December 2018 Page 7 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey Plate 1. Site photographs Site TD-B1 Site TD-B2 Site TD-D1 Site TD-G1 Site TD-H1 Site TD-H2 Site TD-H3 TE 676/18/01 December 2018 Page 8 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey 2 Methods 2.1 Survey The seven sites were surveyed on 29 October 2018. Macro-invertebrate sampling was undertaken by a suitably experienced aquatic ecologist to assess the biological quality of the watercourse at each location. Samples were collected using a standard Freshwater Biological Association (FBA) pattern pond net (mesh size: 1 mm) in accordance with the procedures set out in the Environment Agency’s Operational Instruction 018_08: Freshwater macro-invertebrate sampling in rivers (Environment Agency, 2017). In-stream habitats were sampled using three minutes of active net sampling (predominately ‘kick sampling’ with sweeps amongst any marginal vegetation present), with the three minutes allocated proportionally to the meso- habitats present at each site. This active sampling was accompanied by a one- minute search of the water surface, submerged stones and coarse woody debris etc., for attached and surface-dwelling fauna that might be missed during the three minutes. The samples were then preserved immediately in a solution of 90% Industrial Methylated Spirits (IMS) (denatured ethanol), 5% water and 5% glycerol for transportation to the laboratory and analysis. A variety of environmental data was collected at each site during sampling. Conductivity and pH were recorded with a Hanna Instruments HI9812-5 portable water test meter. Depth and width readings were taken with a measuring pole and estimates of the substrate composition were also made. Site registration data were obtained from a 1:25000 Ordnance Survey map of the area and included: altitude, distance from source, discharge category, slope and National Grid Reference (NGR). A GPS unit was used in the field to check the map referenced NGR of each site. 2.2 Identification and Analysis The samples were sorted by a suitably experienced aquatic biologist and the aquatic macro-invertebrates identified to family taxonomic level (Taxonomic level 2 in RIVPACS IV) in accordance with the protocols outlined in the Environment Agency’s Operational Instruction 024-08: Freshwater macro-invertebrate analysis of riverine samples (Environment Agency,