Rain-Charm House Kyl Cober Parc Stoke Climsland Plymouth PL17 8PH

TREWITHEN DAIRY,

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, PL17 8PH UK Registered in 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 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, 2014).

The environmental and site registration data were entered into the computer package RIVPACS IV (incorporated within the RICT (River Invertebrate Classification Tool) website at http://rict.sepa.org.uk) (Freshwater Biological Association, 2018; Clarke and Davy-Bowker, 2014), see Appendix 1). This software package predicts the taxa and biotic indices at an unimpacted site, based on the environmental data entered. The predicted taxa and indices can then be compared with the observed data, after the analysis of the samples, to assess how the health of the watercourse deviates from expected parameters, and to provide a rating of the biological status (ecological water quality) at each of the sampling sites. RICT incorporates RIVPACS predictive models based on a database of UK reference streams (Freshwater Biological Association, 2018) and calculates the expected indices from the environmental data collected during sampling.

The invertebrate data were analysed using the following indices:

• The Walley Hawkes Paisley Trigg (WHPT) index is primarily designed to assess the impact of organic enrichment on aquatic invertebrate communities,

TE 676/18/01 December 2018 Page 9 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

but can also be used to identify the effects of toxic pollution and physical disturbance. This index is now used by the UK regulatory agencies and supersedes the Biological Monitoring Working Party (BMWP) scoring system which was used up until 2015. Both indices assign a value from one to ten to certain invertebrate families according to their degree of sensitivity to the effects of organic pollution, with the more sensitive families scoring the higher values. The scores for all the taxa in a sample are then totalled to provide an overall WHPT or BMWP score for a sample. The WHPT values take into account the abundance of each invertebrate family within a sample, a factor that was lacking in the old BMWP system. The WHPT index, coupled with RIVPACS IV analysis, is the current tool adopted by the Environment Agency and UK environmental regulatory agencies to classify rivers according to the European Water Framework Directive (WFD). This report includes both WHPT and BMWP values, the latter to enable comparison with the previous surveys. Further information about these indices is given in Appendix 1.

• The Average Score Per Taxon (ASPT) is calculated by dividing the WHPT or BMWP score by the number of scoring taxa (N-TAXA) used to calculate it. This is arguably the most useful score for comparing between samples as it reduces the distorting effect of single / small numbers of very high or low-scoring taxa occurring at a sample site.

• RIVPACS can be used to express WHPT and BMWP indices as Environmental Quality Indices (EQIs) or Ratios (EQRs). An EQI is a biotic index observed at a site, divided by the value expected if the environmental quality was good (i.e. the value predicted by RIVPACS). EQIs remove the effects of natural differences between the invertebrate communities at different sites and so place the biotic indices from all sites on a common scale. The closer to unity the observed and predicted indices are (i.e. the nearer to 1 the EQI value), then the better the water quality of the site. The current version IV of RIVPACS now calculates Ecological Quality Ratios (EQRs) by dividing the observed value by a predicted value, as above, but also incorporates into the calculation bias for sample analysis efficiency and a corrective value that converts RIVPACS predictions into reference values, thereby making the whole system more statistically robust and improving the accuracy of assigning a given reach of watercourse (i.e. a sampling site) to the correct biological status.

• Lotic-Invertebrate Index for Flow Evaluation (LIFE) was used to assess the flow regime to which the invertebrate communities were adapted, ranging from fast to slow flows. This index is of particular relevance for the evaluation of impacts from impoundments and abstractions on the invertebrate communities of a watercourse. Any decline in LIFE scores from the base-line values established in the 2014 surveys would indicate a possible impact from the licensed abstraction on the biota of the surrounding watercourses. It should be noted that the invertebrate samples in the 2014 and 2015 surveys were analysed to the species taxonomic level and hence corresponding LIFE scores in the earlier surveys were calculated from species data and are slightly higher than those based on family level data. To alleviate the difficulties in direct comparison arising from the differences in taxonomic determination, the comparsion of observed LIFE scores with those predicted by RIVPACS was used to derive LIFE EQIs. Values close to unity would indicate no discernible impact on the invertebrate communites arising from low flows. Further details of LIFE are provided in Appendix 2.

TE 676/18/01 December 2018 Page 10 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

3 Results and Discussion

The results from the survey in October 2018 are presented in Tables 2, 3 and 4 below. The 2018 survey confirmed the findings of the 2014, 2015 and 2017 surveys and indicated that all the streams contained exceptionally diverse aquatic invertebrate communities, including taxa sensitive to the effects of organic pollution, and similar in faunal composition to those recorded in 2014, 2015 and 2017. The 2016 survey data (Westcountry Rivers Ltd, 2017) returned lower scores which are inconsistent with data from other years. Given the uniformity between scores in 2014, 2015, 2017 and 2018, it seems unlikely the 2016 scores are representative of the health of the streams so have been excluded from the discussion below, though for completeness are shown in Table 4.

The aquatic invertebrate communities varied in diversity from 31 taxa at H3, the most diverse site, on the upper reaches of the Hollycoombe Stream, to 24 taxa at G1, on the Greymare Stream. This highlights the degree of spatial and temporal variability that can be exhibited by invertebrate sampling, as H3 was previously one of the least diverse sites in the 2017 survey. The taxa recorded were typical of such small, unpolluted, headwater streams, and overall the communities were notable for their diversity, which was exceptional for such small watercourses; a factor that is reflected in their ‘high status’ classifications. The occurrence of the groundwater amphipod Niphargus aquilex (Niphargidae) at site D1 on the Drift Stream is worthy of note. This blind, colourless shrimp is normally recorded in groundwater habitats such as caves, mines wells and boreholes. It is the commonest and most widespread species of the British stygobitic (limited to subterranean waters) crustacean fauna, being common across southern Britain in suitable habitat, but also the most superficial. It is often found in the hyporheic zone of rivers and streams, the zone of intermixing surface and groundwater that is present beneath and beside most watercourses, and there are many records of it being collected during sampling for benthic invertebrates at sites where groundwater upwelling occurs (Proudlove et al. 2003), illustrating the connectivity of the surface watercourses in the area with the underlying aquifer.

The 2018 RIVPACS analysis classified all of the sites as being of high biological status and LIFE EQIs were close to or above unity, indicating no discernible impact on the invertebrate assemblages due to low flows. High biological status and similar LIFE EQIs were also recorded at the seven sites in 2017. The 2014 and 2015 data were not analysed using RIVPACS, although it is likely that the seven sites would also have been classified as either good or high biological status if this had been carried out.

The 2017 and 2018 LIFE scores were marginally lower than those recorded in 2014 and 2015 but this is more likely to reflect a variation in the methodology; as described above, invertebrate samples were analysed to species level in these previous surveys and LIFE scores calculated using species level data are generally greater than those calculated using data at a higher taxonomic level. It should also be noted that the results exhibit a degree of seasonality, in that British riverine invertebrate communities are usually more diverse during the spring season, due to variations in the life cycle of many species of insect with an aquatic nymph or larval life stage (e.g. Ephemeroptera, Plectoptera and Trichoptera); some of these species are absent from riverine habitats later in the year when they are either terrestrial winged adults, or might be present as eggs or early instars deeper in the benthic sediments. The most obvious example of this is the blue-winged olive (Ephemerella ignita, Ephmerellidae), a common inhabitant of many small stony streams in the spring,

TE 676/18/01 December 2018 Page 11 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey which is virtually absent in the autumn. Thus direct comparison of the 2018 LIFE scores should only be made between those generated from autumn season data, i.e. October 2014 and 2017. When comparing the LIFE scores generated from family level data for October 2017 and 2018 there have been very slight declines across the sites but these are of a minimal nature and EQI values continue to suggest no impact on the watercourses. The monitoring of any variation in the LIFE scores should certainly be considered in any future monitoring.

Overall, it is concluded that the current levels of abstraction from the Trewithen Dairy boreholes, in the upper catchments of the streams, are not having an adverse impact on their aquatic invertebrate communities and are sustainable.

TE 676/18/01 December 2018 Page 12 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Table 2. Macro-invertebrate taxa recorded at each site in 2018 Site Number TD-B1 TD-B2 TD-D1 TD-G1 TD-H1 TD-H2 TD-H3 TAXA Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Abun- Abun- Abun- Abun- Abun- Abun- Abun- dance dance dance dance dance dance dance

TRICLADIDA Planariidae 3 0.77 1 0.14 OLIGOCHAETA 11 6.29 32 8.16 9 1.33 3 0.84 10 1.83 2 0.28 4 0.20 GASTROPODA Hydrobiidae 1 0.57 65 16.58 2 0.30 20 3.66 8 1.13 Planorbidae (Ancylus gp.) 3 0.84 2 0.37 10 1.41 3 0.15 BIVALVIA Sphaeriidae 1 0.57 19 4.85 42 6.21 2 0.56 4 0.73 13 0.65 ORIBATEI 2 0.30 CRUSTACEA Niphargidae 1 0.15 Ostracoda 1 0.15 ANISOPTERA Cordulegastridae 1 0.57 2 0.51 4 0.59 1 0.28 3 0.55 4 0.56 2 0.10 ZYGOPTERA Calopterygidae 1 0.05 PLECOPTERA Nemouridae 2 1.14 7 1.79 22 3.25 21 5.88 13 2.38 11 1.55 134 6.70 Perlodidae 4 0.73 6 0.30 Chloroperlidae 1 0.28 1 0.18 1 0.05 Leuctridae 32 18.29 119 30.36 158 23.37 113 31.65 190 34.73 227 31.97 1527 76.39 EPHEMEROPTERA Heptageniidae 1 0.57 7 1.96 21 3.84 52 7.32 13 0.65 Ephemeridae 4 2.29 83 15.17 2 0.28 3 0.15 Leptophlebiidae 1 0.57 3 0.77 46 12.89 6 1.10 7 0.99 7 0.35 Baetidae 2 0.51 2 0.56 25 4.57 14 1.97 7 0.35

TE 676/18/01 December 2018 Page 13 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Site Number TD-B1 TD-B2 TD-D1 TD-G1 TD-H1 TD-H2 TD-H3 TAXA Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Nos. Relative Abun- Abun- Abun- Abun- Abun- Abun- Abun- dance dance dance dance dance dance dance

TRICHOPTERA Sericostomatidae 8 4.57 1 0.15 3 0.84 12 2.19 1 0.14 1 0.05 Odontoceridae 1 0.18 1 0.14 Beraeidae 1 0.26 1 0.15 Goeridae 1 0.57 7 1.28 6 0.30 Lepidostomatidae 3 0.77 7 1.04 2 0.28 2 0.10 Polycentropodidae 2 1.14 7 1.79 8 1.18 17 4.76 3 0.55 2 0.28 11 0.55 Rhyacophilidae 3 1.71 1 0.14 2 0.10 Glossosomatidae 1 0.26 2 0.30 Philopotamidae 4 1.02 4 1.12 6 1.10 33 4.65 93 4.65 Limnephilidae 13 7.43 45 11.48 54 7.99 21 5.88 1 0.18 5 0.70 17 0.85 Hydropsychidae 7 4.00 7 1.79 3 0.44 19 5.32 28 3.94 16 0.80 MEGALOPTERA Sialidae 1 0.18 DIPTERA Chironomidae 54 30.86 22 5.61 303 44.82 59 16.53 100 18.28 148 20.85 34 1.70 Simuliidae 10 5.71 17 4.34 1 0.15 14 3.92 7 1.28 101 14.23 12 0.60 Dixidae 2 1.14 2 0.30 2 0.56 15 2.11 5 0.25 Ptychopteridae 1 0.26 Tipulidae 1 0.57 1 0.15 1 0.28 1 0.05 Pediciidae 2 0.30 1 0.14 3 0.15 Limoniidae 1 0.26 1 0.15 1 0.28 1 0.18 2 0.28 2 0.10 Ceratopogonidae 6 3.43 1 0.26 1 0.28 1 0.18 COLEOPTERA Gyrinidae 1 0.26 12 2.19 10 1.41 14 0.70 Hydraenidae 5 2.86 8 2.04 1 0.28 1 0.05 Elmidae 3 1.71 2 0.51 26 3.85 1 0.28 5 0.91 7 0.99 Scirtidae 3 1.71 17 4.34 4 0.59 14 3.92 6 1.10 14 1.97 57 2.85 Dytiscidae 2 1.14 2 0.51 19 2.81 2 0.37 1 0.14 1 0.05 Nos. of Invertebrates 175 392 676 357 547 710 1999 Nos. of Taxa 25 26 25 24 28 28 31

TE 676/18/01 December 2018 Page 14 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Table 3. Physical variables, floral communities and biological indices for each site

SITE TD-B1 TD-B2 TD-D1 TD-G1 TD-H1 TD-H2 TD-H3 WATERCOURSE Bofarnal Stream Tributary of Drift Stream Greymare Hollycoombe Tributary of Hollycoombe Bofarnal Stream Stream Stream Hollycoombe Stream Stream SX 11548 SX 13721 NGR SX 11748 62919 SX 12109 63174 SX 13051 64953 64453 SX 13594 64946 64125 SX 13569 64217 WIDTH (m) 1.75 0.7 0.6 0.8 4 1.2 0.8 AVERAGE DEPTH (cm) 7 7 4 4 5 8 4 CONDUCTIVITY (Scm-1) 100 200 100 110 110 160 100 pH 6.2 6.1 6.1 6.1 6.7 6.6 6.2 SUBSTRATE (% cover) Marginal / Marginal / Marginal / Silt 3 Overlying 0 0 Overlying 0 Overlying Sand 12 10 1 1 3 3 5 Gravel 50 55 34 14 30 33 35 Pebbles 25 25 40 50 45 34 35 Cobbles 10 10 25 30 22 30 25 Boulders 0 0 0 5 0 0 0 Rock Pavement 0 0 0 0 0 3 0 DISTANCE FROM 1.1 0.2 0.6 0.6 1.5 0.7 0.4 SOURCE (km)

ALTITUDE (m) 83.5 101.5 48.3 47.6 41.9 80 70.9 SLOPE (m / km) 30.77 57.14 44.44 66.67 30.77 44.44 44.44 DISCHARGE CATEGORY 1 1 1 1 1 1 1 FLOW Moderate Moderate Moderate Slow Moderate Moderate Moderate SHADING Medium Medium Heavy Heavy Heavy Heavy Heavy

TE 676/18/01 December 2018 Page 15 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

SITE TD-B1 TD-B2 TD-D1 TD-G1 TD-H1 TD-H2 TD-H3 MACROPHYTE COVER (%) 0 0 0 0 0 0 0 MACROPHYTE SPECIES ** ** ** ** ** ** **

BRYOPHYTE COVER (%) 0 <1 1 1 <1 <1 0 BRYOPHYTE SPECIES ** Platyhypnidium Chiloscyphus Chiloscyphus Chiloscyphus Fissidens sp. ** riparoides polyanthos polyanthos polyanthos, Platyhypnidium riparoides, Fissidens sp.

ALGAL COVER (%) 5 2 3 2 2 2 2 ALGAL SPECIES Benthic Diatoms Benthic Diatoms Benthic Diatoms, Benthic Benthic Diatoms Benthic Benthic Diatoms Encrusting green Diatoms Diatoms spp.

BMWP 145 142 121 133 180 170 193 BMWP N-TAXA 23 24 20 21 27 26 28 BMWP ASPT 6.3 5.92 6.05 6.33 6.67 6.54 6.89 WHPT 163.7 172.6 134 158.6 203.4 188.6 203.5 WHPT N-TAXA 24 26 20 22 28 26 27 WHPT ASPT 6.82 6.64 6.7 7.21 7.26 7.25 7.54 EQR N-TAXA 0.95 1.4 0.87 0.88 1.08 1.03 1.19 EQR ASPT 1.02 1.1 1.02 1.09 1.09 1.1 1.15 BIOLOGICAL STATUS High High High High High High High Observed LIFE Family 7.29 7.04 7 7.47 7.56 7.67 7.5 Predicted LIFE Family 7.57 7.31 7.54 7.55 7.55 7.55 7.51 EQI LIFE Family 0.96 0.96 0.93 0.99 1.001 1.02 0.999

TE 676/18/01 December 2018 Page 16 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Table 4. Comparison of the biological indices associated with the macro- invertebrate surveys 2014-2018

Stream Site Survey No. of BMWP WHPT BMWP LIFE date BMWP Score Score ASPT Score scoring taxa

Bofarnel Stream TD-B1 May-14 26 171 - 6.6 8.2 Oct-14 17 104 - 6.1 7.7 Apr-15 27 187 - 6.9 8.1 Sep-16 10 61 - 6.1 7.6 Oct-17 22 136 162.1 6.18 7.6 Oct-18 23 145 163.7 6.3 7.29

TD-B2 May-14 22 142 - 6.5 8.3

Oct-14 23 142 - 6.2 7.9 Apr-15 27 184 - 6.8 7.9 Sep-16 10 85 - 8.5 7.8 Oct-17 25 152 178 6.08 7.09 Oct-18 24 142 172.6 5.92 7.04

Driftwood Stream TD-D1 May-14 19 120 - 6.3 8.3 Oct-14 15 86 - 5.7 8.2 Apr-15 20 136 - 6.8 8.2 Sep-16 8 56 - 7 7 Oct-17 22 131 155.9 5.95 7.35 Oct-18 20 121 134 6.05 7

Greymare Stream TD-G1 May-14 23 151 - 6.6 8.1 Oct-14 19 117 - 6.2 8 Apr-15 16 111 - 6.9 8.7 Sep-16 8 60 - 7.5 7.7 Oct-17 22 149 181.2 6.77 7.67 Oct-18 21 133 158.6 6.33 7.47

Hollycoombe Stream TD-H1 May-14 18 120 - 6.7 8.6

Oct-14 21 140 - 6.7 8.6 Apr-15 25 174 - 7 8 Sep-16 11 73 - 6.6 8.3 Oct-17 26 171 201.5 6.58 7.67 Oct-18 27 180 203.4 6.67 7.56

TD-H2 May-14 17 107 - 6.3 8.4 Oct-14 19 106 - 5.6 7.6 Apr-15 24 148 - 6.2 8.2 Sep-16 12 78 - 6.5 7.8 Oct-17 25 154 185.1 6.16 7.7 Oct-18 26 170 188.6 6.54 7.67

TE 676/18/01 December 2018 Page 17 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Stream Site Survey No. of BMWP WHPT BMWP LIFE date BMWP Score Score ASPT Score scoring

taxa

Hollycoombe Stream TD-H3 May-14 16 100 6.3 8.3 Oct-14 16 96 - 6 7.8 Apr-15 13 102 - 7.8 8.4 Sep-16 9 55 - 6.1 7.3 Oct-17 21 137 158.7 6.52 7.53 Oct-18 28 193 203.5 6.89 7.5

4 Conclusion

Results showed that all the sites have aquatic invertebrate assemblages of exceptional diversity for such small watercourses, similar in composition to those recorded during previous surveys carried out from May 2014 to October 2017, and classified by RICT as being of high biological status under the Water Framework Directive (WFD). The LIFE scores indicated that the invertebrate communities present are adapted to fast flowing conditions and the scores showed no significant reductions 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.

References

Clarke, R. T. & Davy-Bowker, J. (2014). River Invertebrate Classification Tool Science Development Project: Modifications for WHPT and other Abundance- Weighted Indices. A Report to the Scottish Environment Protection Agency.

Environment Agency (2017). Freshwater macro-invertebrate sampling in rivers. Internal Environment Agency document, Operational Instruction 018_08, Version 7.

Environment Agency (2014). Freshwater macro-invertebrate analysis of riverine samples. Internal Environment Agency document, Operational Instruction 024_08, Version 5.

Extence, C.A., Balbi, D.M. & Chadd, R.P. (1999). River flow indexing using benthic macro-invertebrates: a framework for setting hydro-ecological objectives. Regulated Rivers: Research & Management. 15: 543-574.

Freshwater Biological Association (2018). River Invertebrate Classification Tool (RICT) and RIVPACS. http://www.fba.org.uk/river-invertebrate-classification-tool-rict- and-rivpacs

TE 676/18/01 December 2018 Page 18 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Proudlove, G.S., Wood, P.J., Harding, P.T., Horne, D.J., Gledhill, T. and Knight, L.R.F.D. (2003). A review of the status and distribution of the subterranean aquatic Crustacea of Britain and Ireland. Cave and Karst Science 30 (2): 53-74.

URS (2015) Trewithen Dairy: Macro-Invertebrate & Riparian Habitat Survey. May 2015. URS Infrastructure & Environment UK Limited, Plymouth.

Walley, W.J. and Hawkes, H.A. (1996). A computer-based reappraisal of the Biological Monitoring Working Party scores using data from the 1990 river quality survey of England and Wales. Water Research 30 (9): 2086-2094.

Walley, W.J. and Hawkes, H.A. (1997). A computer-based reappraisal of the Biological Monitoring Working Party score system incorporating abundance rating, site type and indicator value. Water Research 31 (2): 201-210.

Westcountry Rivers Ltd (20171). Trewithen Dairy, Lostwithiel: Macro-invertebrate Survey. January 2017. Reference TE 599_V2. Report to Trewithen Dairy. Westcountry Rivers Ltd, Cornwall.

Westcountry Rivers Ltd (20172) Trewithen Dairy, Lostwithiel: Macro-invertebrate Survey. November 2017. Reference TE 655/17/01. Report to Trewithen Dairy. Westcountry Rivers Ltd, Cornwall.

This report has been produced in good faith, with all reasonable skill, care and diligence based on the information provided and accessible at the time of its preparation and within the scope of the work agreed with the client. We disclaim any responsibility to the client and others in respect of any matters outside the scope of the above. This report is provided for the sole use of the named client and is confidential to them and their professional advisor.

TE 676/18/01 December 2018 Page 19 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Appendix 1. BMWP and WHPT Scoring Systems and RIVPACS Analysis

Prior to 2015, the BMWP (Biological Monitoring Working Party) scoring system was used by the UK environmental agencies to provide an ecological classification of rivers and streams. This scoring system assigned a value of 1-10 to certain invertebrate families, according to their degree of sensitivity to the effects of organic pollution, with the more sensitive families scoring the higher values. The BMWP scores for all the taxa in a sample are then totalled to provide an overall BMWP score for the sample.

The ASPT (Average Score Per Taxon) is calculated by dividing the BMWP score by the number of taxa used to calculate it. This is arguably the most useful score for comparing between samples as it reduces the distorting effect of single / small numbers of very high or low-scoring taxa occurring at a sample site.

The BMWP system was in use from the late 1980s up to 2015 and required updating to better reflect current, better-informed information on the ecology and pollution tolerance of various aquatic invertebrate taxa. Under the initial BMWP system values were allocated to individual taxa based on expert judgement. Comprehensive information is now available from standardised river surveys undertaken across the UK by the Environment Agency, the Environment and Heritage Service for Northern Ireland and the Scottish Environmental Protection Agency. This data enabled Walley and Hawkes (1996, 1997) to carry out an analysis of the results and derive new values for each family and also to incorporate several families not previously included in the BMWP system. Combined with further refinement, this led to the development of the WHPT (Walley Hawkes Paisley Trigg) index, which is now used by the UK regulatory agencies.

The WHPT is calculated in a similar manner to the BMWP with WHPT N-TAXA and WHPT ASPT values also derived during the process. The main difference is that the WHPT values for each family can also be used to take into account that family’s abundance within a sample of aquatic invertebrates, a factor that was lacking in the old BMWP system. The numbers of individuals in each family are given a log abundance value based on the following:

Abundance Category Numerical Abundance

AB1 1-9

AB2 10-99

AB3 100-999

AB4 >1000

A WHPT value is then assigned to each family according to its abundance in a sample; for example, for Asellidae based on presence only the WHPT score is: 2.8; AB1: 4; AB2: 2.3; AB3: 0.8 and AB4: -1.6, reflecting the fact that hoglice are an important natural component of the biota of many watercourses but when present in very high numbers are bio-indicators of organic pollution. WHPT values are assigned in this way to all families in a sample and then totalled, with the ASPT derived as in the BMWP system above.

Both the BMWP and WHPT scoring systems are designed for use with lotic sites and are only applicable to samples of invertebrates collected using the Environment Agency’s standard methods. Although, primarily designed to detect the effects of organic pollution, both systems can also respond to the effects of toxic pollution and physical disturbance. Sites of identical physical characteristics are often hard to locate along a watercourse and direct comparison cannot always be made. The computer program RIVPACS (River

TE 676/18/01 December 2018 Page 20 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

InVertebrate Prediction And Classification System) can be used to express BMWP indices as Environmental Quality Indices (EQIs) or Ratios (EQRs). An EQI is a biotic index observed at a site, divided by the value expected if the environmental quality was good (i.e. the value predicted by RIVPACS). EQIs remove the effects of natural differences between the invertebrate communities at different sites and so place the biotic indices from all sites on a common scale. The closer to unity the observed and predicted indices are (i.e. the nearer to 1 the EQI value), then the better the water quality of the site.

Until 2013 RIVPACS III was used to generate predicted BMWP indices and hence the calculation of EQIs and the classification of watercourses. In 2013 this was superseded by RICT (River Invertebrate Classification Tool), incorporating new RIVPACS IV predictive models as the official tool for Water Framework Directive (WFD) macro- invertebrate classification by the UK environmental agencies. RICT calculates Ecological Quality Ratios (EQRs) by dividing the observed value by a predicted value, as above. It also incorporates into the calculation bias for sample analysis efficiency and a corrective value that converts RIVPACS predictions into reference values, in essence making the whole system more statistically robust and improving the accuracy of assigning a given reach of watercourse (i.e. a sampling site) to the correct biological status. Prior to 2015, RICT could produce predicted WHPT values but was unable to classify watercourses using WHPT alone and for this reason BMWP scores continued to be used. This deficiency was addressed during 2015 and the data for river quality surveys carried out by the UK environmental agencies in 2015 was subsequently analysed using RICT and WHPT scores, which is now the standard approach adopted by these agencies in all future WFD monitoring.

TE 676/18/01 December 2018 Page 21 Report version 1 Westcountry Rivers Ltd Trewithen Dairy, Lostwithiel Macro-invertebrate Survey

Appendix 2. Lotic-Invertebrate Index for Flow Evaluation (LIFE)

The Lotic-invertebrate Index for Flow Evaluation (Extence, Balbi & Chadd, 1999) is based on the recognised flow associations of different macro-invertebrate species and families. Taxa are assigned a flow score (fs) calculated from a matrix (shown in the table below) based on the affiliation of the species / family for a certain flow regime and the estimated abundance of that species in a sample.

Flow Groups Abundance Categories A B C D / E I: Rapid 9 10 11 12 II: Moderate / Fast 8 9 10 11 III: Slow / Sluggish 7 7 7 7 IV: Flowing / Standing 6 5 4 3 V: Standing 5 4 3 2 VI: Drought Resistant 4 3 2 1

Standard Environment Agency macro-invertebrate abundance categories are shown in the table below:

Estimated Category Abundance A 1-9 B 10-99 C 100-999 D 1000-9999 E 10000 +

The greater the association a certain species has for a faster flow regime the higher the flow score for that species. The Lotic-invertebrate Index for Flow Evaluation is calculated by totalling the flow scores for all the taxa in a sample and dividing the result by the number of taxa used to calculate it.

The greater the number of species associated with fast flows in a sample, the greater will be the LIFE score for that sample. LIFE scores can be used as an indication of possible impacts from low flows on the macro-invertebrate communities of watercourses. Abnormally low scores for sites expected to have a fauna associated with fast flows could indicate an impact from over-abstraction of water or the effects of impoundment etc. Similarly changes in scores over time at a reference site can provide an indication of changing flow regime within the watercourses whether for the better or worse. Note that the attainment of high LIFE scores is not the aim of the index. Sites on sluggish, lowland rivers will naturally have low LIFE scores and this should not be interpreted as being any sign of an impact. The value of LIFE scores comes in monitoring their variation over time at a site or group of sites of similar characteristics.

Species in the same invertebrate family often show variation in their flow requirements and hence will have different flow scores. This means that LIFE scores calculated using species level data are inherently more accurate than those calculated using Family level data. RICT has recently been developed to predict both species and Family level LIFE scores and hence produce LIFE EQIs although it currently lacks the ability to classify watercourse reaches using LIFE. This is in development and is likely to be employed by the regulatory agencies in the near future.

TE 676/18/01 December 2018 Page 22 Report version 1