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Table 5 Comparison of responsive and unresponsive lakes

From: What is the influence of a reduction of planktivorous and benthivorous fish on water quality in temperate eutrophic lakes? A systematic review

  Responsive lakes (significant improvement) Unresponsive lakes (no significant improvement)
  Mean 95% C.I. n Mean 95% C.I. n
Response: Secchi depth 1–3 years after manipulation (vs. before manipulation)
Lake area (ha) 18 10 – 32 19 40 14 – 119 8
Mean depth (m) 1.7 1.3 – 2.2 19 1.8 1.3 – 2.5 8
Retention time (days) 171 63 – 461 11 409 221 – 754 5
Pre-manipulation TP (μg/l) 144 93 – 223 19 127 62 – 260 6
Mean atmospheric temperature (°C) 8.0 7.0 – 9.0 19 7.8 6.4 – 9.2 8
Duration of main manipulation (yr) 2.1 1.6 – 2.5 19 2.4 1.5 – 3.3 8
Fish removal (kg/ha) 233 160 – 338 18 251 198 – 317 7
Fish removal (kg/ha/yr) 124 84 – 183 18 119 70 – 203 7
Fish stock depletion (%) 56 37 – 76 13 40 17 – 62 5
Response: Chlorophyll a 1–3 years after manipulation (vs. before manipulation)
Lake area (ha) 12 5 – 36 12 35 14 – 86 15
Mean depth (m) 1.3 1.1 – 1.6 11 1.8 1.4 – 2.4 15
Retention time (days) 78 22 – 275 4 210 103 – 428 9
Pre-manipulation TP (μg/l) 196 120 – 322 12 126 83 – 190 13
Mean atmospheric temperature (°C) 8.1 7.1 – 9.1 12 8.2 7.5 – 8.9 15
Duration of main manipulation (yr) 2.0 1.4 – 2.6 12 2.0 1.5 – 2.5 15
Fish removal (kg/ha) 250 149 – 420 11 272 184 – 403 12
Fish removal (kg/ha/yr) 137 74 – 252 11 140 98 – 202 12
Fish stock depletion (%) 78 56 – 99 7 58 42 – 75 12
  1. Data are based on the selected dataset, with stocking-only interventions excluded. Lake areas, mean depths, retention times, pre-manipulation TP concentrations and fish removals were log-transformed before calculation of means and confidence intervals, and then back-transformed.