Effects of different wavelengths and intensities of visible light on the hatching success of Acartia tonsa Dana eggs

Mass production of copepod eggs in intensive systems has recently been demonstrated to be economically feasible; a few companies producing copepod eggs have been established. It is well documented that water physiochemical variables could significantly influence the hatching success of Acartia tonsa Dana, 1849 (Copepoda: Calanoida) eggs. This information is important to end users in order to achieve a predictable output of nauplii when hatching eggs for live feed production in marine larviculture. The effect of different wavelengths and intensities of light on the 48-h egg hatching success (HS) of fresh and cold-stored (2 A degrees C) A. tonsa eggs were examined in the present study. No correlations were observed between HS and light environment for fresh or cold eggs when they were hatched at wavelengths between 400 and 630 nm and at light intensities of 0.0016, 1, 5 and 16 A mu E m(-2) s(-1). Fresh eggs displayed the highest HS and declined with the time of storage. However, eggs being of same age showed a similar HS regardless of the light intensity and wavelength, including when hatched in darkness. We suggest that A. tonsa eggs produced in intensive cultures can be hatched without any concern to the light environment.