Watercress and Water Quality: The Effect of Phenethyl Isothiocyanate on the Mating Behaviour of Gammarus pulex

Table 1

Summary of ET₅₀ values. The proportional data were arcsine square root transformed and the ET₅₀ calculated using maximum-likelihood probit or logit analysis. WW1–WW5: samples of watercress wash water. P1–P5: samples of PEITC solution.

Sample	ET50 (minutes)	95% confidence intervals
WW1	77*	73–85
WW2	106*	103–110
WW3	89	78–102
WW5	84	72–93
P1	48	38–56
P2	119	108–133
P3	85	77–92
P5	40	20–56

*Calculated using logit model—all others with probit.