Figure 5. Test of the hypothesis of no migration.

Weighted mean depth Z_m of small, medium and large Mnemiopsis leidyi as a function of time from solar noon at Anholt 24-hour station, where the latter was used as a proxy for the daily variation in surface light intensity. Error bars are the spread Z_s (m) around the mean depth. The lines are the linear regressions (Table 2), where the asterisk indicates statistical significance. The symbols are slightly shifted to facilitate readability.