River Nore, Kilkenny Ecological Assessment. December 2015

Transcription

1 River Nore, Kilkenny Ecological Assessment December 2015 Prepared by: Pascal Sweeney M.Sc., MCIEEM Sweeney Consultancy, Rahan, Mallow Co. Cork. Tel. 022/26780

2 TABLE O CONTENTS 2 Page SECTION 1 INTRODUCTION 3. SECTION 2 METHODOLOGY 3. SECTION 3 RESULTS 4. SECTION 4 CONCLUSIONS 5. APPENDIX 1 SAMPLING SITE DETAILS 6. APPENDIX 2 PHOTOGRAPHS O SAMPLING SITES 8. APPENDIX 3 MACROINVERTEBRATE RESULTS 10. APPENDIX 4 REERENCES 12.

3 1. INTRODUCTION 3 Pascal Sweeney was commissioned to conduct an aquatic macroinvertebrate survey of a section of the River Nore in Kilkenny City from upstream of bridge construction works to the weir downstream. The purpose of this survey is to determine the current ecological status of this section of river, to compare the 2015 results with those of a survey carried out on 27/11/2014 and to assess the significance of ecological impacts arising from construction works at the site of the new bridge. 2. METHODOLOGY 2.1 ieldwork. ield work was carried out by on 27 th November, At the same four sites in the River Nore as were sampled on 27 th November, 2014, macroinvertebrate sampling was carried out in accordance with EPA Standard Operating Procedure (Bradley et al., 2015) and the condition of the substratum was observed. Physical conditions recorded are presented in Appendix 1 and photographs are presented in Appendix Sample Analysis Macroinvertebrates were identified to the taxonomic level required for the EPA Q-scheme. At sites where the Q-scheme methodology was applicable, a Q-value was determined based on the abundance of indicator groups and other relevant environmental data, in accordance with the EPA Standard Operating Procedure (Bradley et al., 2015).

4 3. RESULTS 4 Macroinvertebrate results are presented in Appendix 3. Site 1. The fauna of this eroding site is dominated by EPA Indicator Group C (Relatively Pollution Tolerant), two species of flat mayfly from Group A (Very Pollution Sensitive) are present in low numbers. Groups D (Very Pollution Tolerant) and E (Most Pollution Tolerant) are also present in low numbers. The low representation of Group A taxa in a fauna dominated by Group C, with little representation of Groups D and E, indicates a Q-value of Q3-4. Site 2. While the overall abundance and species diversity of the invertebrates at this site is slightly lower than would be expected, the fauna is far better balanced than was the case in Group C species dominate, with groups A, B and D present in low numbers. The low representation of Group A taxa in a fauna dominated by Group C, with little representation of Group D, indicates a Q-value of Q3-4. Site 3. The fauna found at this site is similar to that found in It is typical of slack, silted conditions, with decaying organic debris. It is unsuitable for assessment by the Q- scheme methodology. Site 4. As at Site 1, the fauna of this eroding site is dominated by Indicator Group C, with one species of flat mayfly from Group A present in low numbers. Groups B and D are poorly represented and Group E is absent. The low representation of Group A taxa in a fauna dominated by Group C, with little representation of Group D, indicates a Q-value of Q3-4.

5 4. CONCLUSIONS The biological water quality of this section of the River Nore has declined slightly since it was sampled in November This decline is not due to the works at the new bridge, as it is evident at Site 1, upstream of Green s Bridge, where Q4 was recorded in November 2014 and Q3-4 was recorded in November At the new bridge, the overall abundance and diversity of invertebrates is lower than at the Site 1, but compared to the fauna found here in 2014, it is far more typical of what would be expected at a site of this nature. The invertebrate fauna in the immediate vicinity of the new bridge has almost recovered from the disturbance caused by the construction works. The substratum and the fauna recorded at Site 3, upstream of the weir, is very similar to what was found in November It would therefore appear that this site is in its natural condition for the prevailing physical habitat and that silt generated by the works did not contribute significantly to the silted substratum in the slack water immediately upstream of the weir. Downstream of the weir, the biological water quality of the river is at Q3-4, the same as upstream of the bridge works, indicating that the bridge works have had no significant impact on the river at this point.

6 6 APPENDIX 1 RIVER NORE SAMPLING SITE DETAILS Site Code 1 GPS Reading S Location Upstream of Green s Br. Photograph No. 1 Sampling depth (m) 0.6 low Riffle: 50% Glide/Run: 50% Substrate 1. Cobble 2. Gravel Instream Vegetation Ranunculus sp. 5% ontinalis antipyretica 20% Site Code 2 GPS Reading S Location At works site Photograph No. 2 Sampling depth (m) 0.7 low Glide: 100% Substrate 1. Limestone Cobble 2. Sand Instream Vegetation None

7 7 Site Code 3 GPS Reading S Location Immediately upstream of weir Photograph No. 3 Sampling depth (m) 0.5 low Glide/Run: 100% Substrate 1. Silt 2. ine Sand 3. Leaf Litter Instream Vegetation Sparganium emersum <5% Site Code 4 GPS Reading S Location Immediately downstream of weir Photograph No. 4 Sampling depth (m) 0.7 low Riffle: 50% Run: 50% Substrate 1. Cobble 2. Gravel 3. Boulder Instream Vegetation None

8 APPENDIX 2 PHOTOGRAPHS O SAMPLING SITES 8 Photo 1: Site 1, Upstream of Green s Bridge Photo 2: Site 2, At Construction Site

9 9 Photo 3: Site 3, Upstream of Weir Photo 4: Site 4, Downstream of Weir

10 APPENDIX 3 Macroinvertebrate Community Composition 10 Relative abundance expressed as D: Dominant; N: Numerous; C: Common; : ew; SS: Single Specimen TAXON SITE 1 SITE 2 SITE 3 SITE 4 EPA Group A (Sensitive) Ecdyonurus sp. SS Heptagenia sp. EPA Group B (Less Sensitive) Glossosomatidae SS Sericostomatidae SS EPA Group C (Relatively Tolerant) Piscicola geometra SS SS Ancylus fluviatilis Planorbidae SS Valvata piscinalis Potamopyrgus antipodarum C Gammarus sp. N N N Baetis rhodani C Serratella ignita SS Caenis sp. SS Hydropsychidae Rhyacophilidae SS Polycentropodidae Haliplidae Gyrinidae Elmis aenea Tipula sp. SS SS Simuliidae Ceratopogonidae Chironomidae (ex. Chironomus) C C N EPA Group D (Very Tolerant) Pisidium sp. C Glossiphonidae Asellus aquaticus C EPA Group E (Most Tolerant) Tubificidae N

11 11 APPENDIX 4 REERENCES Bradley, C., Lucey, J., McGarrigle, M. and McCreesh, P. (2015). Standard Operating Procedure for River Biological Monitoring ield Sampling Surveys. Version 1.4. EPA.