Seasonal changes of environmental parameters in Kuala Ibai, Malaysia during the sampling period A monthly changes in the salinity and temperature of the surface water at the sampling site (represented by our data at the end of each month) B monthly changes in the amount of rainfall and average air temperature at Kuala Ibai based on the data of Malaysian Meteorological Department C monthly changes of the maximum height of sea level at high tide (closed circles), with the height of sea level at high tide on each sampling date (x marks), based on the data of Worldwide Tides and Currents Predictor (2018). The asterisks indicate the months when the swimming epitokes of Neanthes glandicincta appeared.