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Table 3 Cumulative time of various embryonic stages of H. elegans in control seawater and in different concentrations of phorate in seawater (temp. 28 ± 0.2 °C, salinity 34 ± 0.1‰, pH 8.1 ± 0.1); n = 6 ± =SD

From: The toxic effects of phorate on early embryonic stages of sedentary polychaete Hydroides elegans (Haswell, 1883)

Developmental stage Control Times in minutes
Concentration of phorate in ppm
0.05 0.1 0.25 0.5 1 2 5 10 20 30 50
FM stage 5.20 ± 0.28 7.50 ± 0.70 9.00 ± 1.41 11.50 ± 4.24 12.50 ± 4.95 14.50 ± 4.95 16.00 ± 7.07 18.00 ± 7.07 19.50 ± 7.77 21.50 ± 6.36 24.00 ± 7.07 N.D
2-cell stage 31.70 ± 1.63 35.00 ± 1.41 38.50 ± 3.53 42.00 ± 8.48 45.50 ± 9.91 49.50 ± 10.60 52.50 ± 12.02 56.50 ± 12.84 59.50 ± 12.84 63.50 ± 10.84 69.00 ± 14.14 N.D
3-cell stage 42.00 ± 1.30 47.00 ± 2.82 51.50 ± 4.95 56.50 ± 12.02 63.50 ± 13.43 68.00 ± 15.55 73.50 ± 1.67 79.50 ± 11.92 84.50 ± 10.33 90.00 ± 8.04 N.D N.D
4-cell stage 53.60 ± 1.29 59.50 ± 3.53 66.00 ± 7.07 72.50 ± 1.26 82.00 ± 1.38 88.00 ± 8.79 95.50 ± 2.74 103.50 ± 3.40 110.50 ± 4.82 117.00 ± 12.94 N.D N.D
8-cell stage 64.60 ± 0.70 75.50 ± 4.95 81.00 ± 9.89 89.00 ± 4.21 101.00 ± 2.62 108.00 ± 5.45 118.00 ± 0.00 128.00 ± 3.18 137.00 ± 4.01 145.50 ± 6.71 N.D N.D
16-cell stage 76.10 ± 3.48 86.00 ± 5.65 97.00 ± 11.3 107.00 ± 2.45 120.00 ± 4.47 129.00 ± 3.11 141.00 ± 3.18 153.00 ± 4.66 164.00 ± 5.49 176.70 ± 7.34 N.D N.D
32-cell stage 87.70 ± 1.97 99.00 ± 7.07 107.50 ± 12.5 123.00 ± 2.69 139.00 ± 8.52 151.00 ± 3.77 164.50 ± 4.54 178.50 ± 5.44 193.00 ± 5.56 N.D N.D N.D
64-cell stage 98.90 ± 3.21 112.00 ± 7.07 127.50 ± 1.25 139.00 ± 3.94 159.50 ± 0.47 172.00 ± 4.42 187.50 ± 1.61 103.50 ± 8.93 226.00 ± 7.81 N.D N.D N.D
Blastula stage 126.90 ± 2.93 141.00 ± 8.48 157.50 ± 1.26 172.00 ± 3.77 195.50 ± 4.30 209.50 ± 8.96 126.50 ± 5.27 245.50 ± 10.98 N.D N.D N.D N.D
Blastula start rotation stage 154.90 ± 4.58 171.00 ± 8.48 189.50 ± 2.19 204.50 ± 4.30 230.50 ± 6.54 242.00 ± 5.98 266.00 ± 2.22 287.00 ± 7.95 N.D N.D N.D N.D
Blastula stop rotation stage 245.00 ± 1.41 251.00 ± 9.89 261.00 ± 2.26 273.50 ± 8.54 298.50 ± 5.96 307.00 ± 4.49 326.00 ± 0.00 342.50 ± 7.24 N.D N.D N.D N.D
Release stage 300.50 ± 2.12 309.00 ± 11.33 321.50 ± 2.34 336.50 ± 4.79 365.00 ± 4.66 379.00 ± 1.91 402.50 ± 8.69 421.50 ± 6.58 N.D N.D N.D N.D
  1. N.D no development. Number of eggs/embryos observed in each concentration = 100–150, n = number of experiments