Rotifer Diapausing Eggs (Cysts) Hatching Guide

To initiate rotifer cultures by hatching Brachionus manjavacas/plicatilis  diapausing eggs, inoculate them into a 1–100 l culture of live microalgae grown to a density of about 10⁵–10⁶ cells/ml.

Many algae species are suitable, including Tetraselmis, Nannochloropsis, Chlorella, Isochrysis, and Dunaliella, grown at temperatures of 15–32°C and salinities of 15–35 ppt.

Empty one envelope of Brachionus manjavacas/plicatilis  diapausing eggs/l into the algae culture and expect hatching in about 24 h if temperature is 25°C. Lower temperatures will slow hatching to 72 or even 96 h.

Note:  B. rotundiformis cysts take at least 48 h to hatch at 25°C. Longer if incubated at lower temperatures. Also, salinities higher than 15 ppt can slow hatching. Keep checking the hatching dish for several days until hatching is observed.

Light is important, so hatching should occur under fluorescent or LED lights. If you hatch rotifer cysts in a petri dish, it should be placed about 15 cm from the light.

Diapausing egg hatchlings initiate rapid asexual reproduction when provided with abundant food and soon enter log-phase population growth.

After about 1 week, depending on temperature, the culture will contain a dense population of rotifers, free of contaminants, that is suitable for inoculating mass culture production tanks.