Potential impact of cattle access on the ecological quality of rivers: some observations from Ireland

Transcription

1 Potential impact of cattle access on the ecological quality of rivers: some observations from Ireland M. Kelly-Quinn, E. Conroy, J. Turner, A. Rymszewicz, J.J. O Sullivan, D. Lawlor, M. Bruen,

2 SILTFLUX Objectives Increase knowledge and understanding of sediment flux in rivers to help set standards for suspended solids flux and concentrations for the protection of sensitive catchments in Ireland. Assess the benefits of sediment reduction measures. Investigate the relationship between concentrations/flux of sediment and the potential for deposition and ecological impacts. Literature review available shortly from the EPA website * Funding for this research was provided by the Environment Protection Agency, Ireland under the EPA STRIVE Programme (SILTFLUX 2010-W-LS-4).

3 The Context

4 Comparison of Ecological Status between the two survey periods ( (n= 1,573) and (n=1,624) Map of ecological status for monitored river water bodies (n = 1,624) based on the lowest status by quality element and the lowest status by monitoring station within each water body. From: Bradley, C., Byrne, C., Craig, M., Free, G., Gallagher, T., Kennedy, B., Little, R., Lucey, J., Mannix, A., McCreesh, P., McDermott, G., McGarrigle, M., Ní Longphuirt, S., O Boyle, S., Plant, C., Tierney, D., Trodd, W., Webster, P., Wilkes, R. & Wynne, C. (2015) Water quality in Ireland Environmental Protection Agency, Wexford.

5 Trends in the 13,300 km baseline showing the percentage of surveyed channel nationally in the four EPA biological quality classes Long-term trends in the percentage number of high ecological quality (macroinvertebrate) river sites ( ). From: Bradley at al. (2015) Water quality in Ireland Environmental Protection Agency, Wexford.

6 Considerable Challenges 47% of river water bodies require improvements (Bradley et al. 2015) Many river sites seems to be stuck with slight and moderate pollution for several decades. We have not yet recovered some 6% of unpolluted river channel lost during the 1990s. Of the river considered to be at high status few are at the highest rating Q5 (reference sites). The period saw a seven fold decrease in the number of Q5 sites. The number of Q5 sites continues to decline from 38 ( ) to 27 ( ) additional measures are required to improve water quality..

7 Small streams are particularly vulnerable 77% Represented by just over 10% of sites in the EPA monitoring programme Spring Summer Autumn Winter Spring Typical seasonal changes in status of small streams in agricultural catchments Good Moderate Poor

8 In agriculture, primarily diffuse losses, including farmyard losses, siltation due to bank erosion, cattle access to streams, and losses from tillage land, were suspected. From: Bradley et al. (2015) From: Bradley at al. (2015) Water quality in Ireland Environmental Protection Agency, Wexford.

9 64% Agriculture Forestry Other 81% From: DAFM Fact Sheet on Irish Agriculture October (2013) Department of Agriculture, Food and the Marine Pasture, Hay & Silage 11% 8% Rough Grazing Crops, Fruit & Horticulture 2015 Figures (CSO) million dairy cattle million beef cattle Rivers/streams provide access to free water

10 Extent of cattle access to watercourses?

11 76 in 10km

12 113 in 13km

13 Yellow and Castlejordan Rivers

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16 Cattle Access Study Study was mainly based on macroinvertebrates

17 Study sites Eight sites - four good(min.) and four moderate (max.) water quality status upstream of cattle access point The WFD typology of the sites was type 31 (calcareous geology with low slope)

18 Schematic diagram showing sampling locations (not to scale) Six replicate Surber samples were taken within the mid-channel and margins at each sampling location in April/May and September/October 2013 Also measured: Patch scale visual estimations of % deposited fine sediment (< 2 mm) Re-suspendable sediment from the stream bed Once-off low and high flow water chemistry Once-off sediment chemistry (total Kjeldahl nitrogen, total P and organic matter (%) (loss on ignition method)

19 Significant impacts in mid-channel riffle/run habitat Significant interactions between time, location & site (-/+ = direction of change; ns=not significant) Taxon % EPT Taxon % EPT E Community % % % Richness richness abundance abundance abundance structure Microhabitat Feeding Locomotion Barrow - Autumn - Spring - Autumn - Autumn - Autumn - Autumn ns ns ns Douglas + ns Autumn + ns ns ns ns Autumn ns Clodiagh - Spring - ns ns Spring - Autumn Autumn Autumn Spring Glenlahan + Spring - Autumn + Spring - ns Spring Autumn ns Spring Autumn Spring D arcy s ns ns ns ns ns ns ns ns ns Boycetown ns ns ns Spring - Spring - Spring Autumn ns Spring Spring Dee + Autumn + Spring* + Autumn + Spring* + Spring Autumn Spring Spring Autumn Spring Erkina ns ns ns ns ns ns ns ns Spring * - increase largely due to pollution tolerant Serratella ignita

20 EPT are sensitive to deposited sediment Data from mesocosm experiments (Conroy unpublished)

21 Contributors to differences in community structure some examples River/ season Glenlahan spring Taxa Average abundance u/s Average abundance d/s % Contribution Culicidae Chironomidae Baetis spp Rhithrogena semicolorata Boycetown spring Dee spring Barrow autumn Gammarus duebeni Oligochaeta Hydropsyche spp Baetis spp Rhithrogena semicolorata Limnius volckmari Oligochaeta Elmis aenea Gammarus duebeni Chironomidae Serratella ignita Baetis spp Elmis aenea Chironomidae Leuctra spp Oligochaeta Baetis spp

22 Sediment cover and benthic sediment chemistry Sediment chemistry No upstream-downstream differences in visual estimation of % sediment surface cover Significant interaction between time, site and location was detected for resuspendable sediment significantly higher downstream re-suspendable sediment in the Barrow, Erkina and the Glenlahan autumn samples.

23 Cattle Access Key findings No clear consistent biological response to cattle access, however there was some evidence of site specific impacts downstream of cattle access points Impacts most common in the good/high status rivers Impact in moderate status rivers probably related to high or prolonged livestock activity Factors influencing the potential for impact are largely unknown but are likely to be related to the intensity/duration of cattle access, topography, flow, existing water quality, sediment quality (both nutrient and organic content), nutrients inputs, etc. Extent of impact and that resulting from multiple access points are unknown 23

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25 Overview of the research Aim - assess the environmental, ecological and socio-economic impact of existing and potential measures that prevent cattle access to watercourses. Objectives: Assess the impact of cattle access and in-stream activity on water chemistry (more regular sampling including period when cattle are in the stream) sediment parameters freshwater biology (macroinvertebrates, diatoms and faecal indicator bacteria) on hyporheic water chemistry and invertebrate fauna. Assess the extent of ecosystem impact and recovery at a spatial-scale downstream of cattle access points. Assess the impact of proposed cattle exclusion measures on the parameters above. Determine the cost-effectiveness of fencing (and alternatives) to improve the condition of watercourses. existing and novel water provision mechanisms. Estimate the proportion of farms that have flowing or still water on or adjacent to their land parcel, Assess willingness to adopt cattle exclusion measures and determine level of incentives required to ensure adequate participation in voluntary cattle exclusion measures.

26 xperimental Design X3 catchments Moderate water quality status/intensively managed sites Each sampled upstream and at a several points downstream (to assess recovery) Uppermost site used to compare affect of single access point (replication between catchments) High water quality status/extensively managed sites Other sites to assess the cumulative impact of multiple access points

27 Objectives: Assess the impact of cattle access and in-stream activity on Water chemistry sediment parameters freshwater biology (macroinvertebrates, diatoms and faecal indicator bacteria) on hyporheic water chemistry and invertebrate fauna. Assess the extent of ecosystem impact and recovery at a spatial-scale downstream of cattle access points. Assess the impact of proposed cattle exclusion measures on the parameters above. Determine the cost-effectiveness of fencing (and alternatives) to improve the condition of watercourses. existing and novel water provision mechanisms. Estimate the proportion of farms that have flowing or still water on or adjacent to their land parcel. Assess willingness to adopt cattle exclusion measures and determine level of incentives required to ensure adequate participation in voluntary cattle exclusion measures.

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