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

Figure 1

Mean cumulative proportion of pairs separated (±SE). Precopular pairs were exposed at Time = 0, the mean of 4 tests over the course of the 2 h exposure is shown for each test substance (carried out on separate occasions, with a total of 119 pairs exposed to wash water, 105 pairs exposed to PEITC) and the control (mean of 8 tests, with a total of 157 pairs exposed). Vertical bars show standard error; 𝑛 denotes the number of tests. There was immediate separation of at least one pair in all the PEITC test solutions (i.e., by the first 15-minute reading). There was separation of at least one pair in all the watercress wash water test solutions after 45 minutes. There was a steady increase in the number of pairs separated over the course of the two-hour test to 70% or greater in all wash water test solutions (maximum 95%, mean 84%) at the test end. The pattern of response for the PEITC solution was very similar (maximum 100%, mean 85%) at test end.