TY - JOUR
T1 - Influence of stormflow and baseflow phosphorus pressures on stream ecology in agricultural catchments
AU - Shore, M.
AU - Murphy, S.
AU - Mellander, P.-E.
AU - Shortle, G.
AU - Melland, A.R.
AU - Crockford, L.
AU - O'Flaherty, V.
AU - Williams, L.
AU - Morgan, G.
AU - Jordan, P.
PY - 2017/7/15
Y1 - 2017/7/15
N2 - Abstract Stormflow and baseflow phosphorus (P) concentrations and loads in rivers may exert different ecological pressures during different seasons. These pressures and subsequent impacts are important to disentangle in order to target and monitor the effectiveness of mitigation measures. This study investigated the influence of stormflow and baseflow P pressures on stream ecology in six contrasting agricultural catchments. A five-year high resolution dataset was used consisting of stream discharge, P chemistry, macroinvertebrate and diatom ecology, supported with microbial source tracking and turbidity data. Total reactive P (TRP) loads delivered during baseflows were low (1-7 of annual loads), but TRP concentrations frequently exceeded the environmental quality standard (EQS) of 0.035 mg L-1 during these flows (32-100 of the time in five catchments). A pilot microbial source tracking exercise in one catchment indicated that both human and ruminant faecal effluents were contributing to these baseflow P pressures but were diluted at higher flows. Seasonally, TRP concentrations tended to be highest during summer due to these baseflow P pressures and corresponded well with declines in diatom quality during this time (R2 = 0.79). Diatoms tended to recover by late spring when storm P pressures were most prevalent and there was a poor relationship between antecedent TRP concentrations and diatom quality in spring (R2 = 0.23). Seasonal variations were less apparent in the macroinvertebrate indices; however, there was a good relationship between antecedent TRP concentrations and macroinvertebrate quality during spring (R2 = 0.51) and summer (R2 = 0.52). Reducing summer point source discharges may be the quickest way to improve ecological river quality, particularly diatom quality in these and similar catchments. Aligning estimates of P sources with ecological impacts and identifying ecological signals which can be attributed to storm P pressures are important next steps for successful management of agricultural catchments at these scales.
AB - Abstract Stormflow and baseflow phosphorus (P) concentrations and loads in rivers may exert different ecological pressures during different seasons. These pressures and subsequent impacts are important to disentangle in order to target and monitor the effectiveness of mitigation measures. This study investigated the influence of stormflow and baseflow P pressures on stream ecology in six contrasting agricultural catchments. A five-year high resolution dataset was used consisting of stream discharge, P chemistry, macroinvertebrate and diatom ecology, supported with microbial source tracking and turbidity data. Total reactive P (TRP) loads delivered during baseflows were low (1-7 of annual loads), but TRP concentrations frequently exceeded the environmental quality standard (EQS) of 0.035 mg L-1 during these flows (32-100 of the time in five catchments). A pilot microbial source tracking exercise in one catchment indicated that both human and ruminant faecal effluents were contributing to these baseflow P pressures but were diluted at higher flows. Seasonally, TRP concentrations tended to be highest during summer due to these baseflow P pressures and corresponded well with declines in diatom quality during this time (R2 = 0.79). Diatoms tended to recover by late spring when storm P pressures were most prevalent and there was a poor relationship between antecedent TRP concentrations and diatom quality in spring (R2 = 0.23). Seasonal variations were less apparent in the macroinvertebrate indices; however, there was a good relationship between antecedent TRP concentrations and macroinvertebrate quality during spring (R2 = 0.51) and summer (R2 = 0.52). Reducing summer point source discharges may be the quickest way to improve ecological river quality, particularly diatom quality in these and similar catchments. Aligning estimates of P sources with ecological impacts and identifying ecological signals which can be attributed to storm P pressures are important next steps for successful management of agricultural catchments at these scales.
KW - Stormflow
KW - Agriculture
KW - Baseflow
KW - Phosphorus
UR - https://pure.ulster.ac.uk/en/publications/influence-of-stormflow-and-baseflow-phosphorus-pressures-on-strea-3
U2 - 10.1016/j.scitotenv.2017.02.100
DO - 10.1016/j.scitotenv.2017.02.100
M3 - Article
C2 - 28284645
VL - 590/1
SP - 469
EP - 483
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -