As for other environmental conditions, optimal hatching outputs are reached in the pH range
8-8.5. As a consequence, the addition of NaHC3, up to 2 g.l-1, to artificial or diluted
seawater or to dense suspensions of cysts results in improved hatching. This might be
related to the optimal pH activity range for the hatching enzyme.
An increased hatching has been reported with increasing oxygen level in the range 0. 6 and 2
ppm, and maximal hatching obtained above this concentration. To avoid oxygen gradients
during hatching it is obvious that a good homogeneous mixing of the cysts in the incubation
medium is required.
As stated above, hatching in a higher salinity medium will consume more of the energy
reserves of the embryo. Above a threshold salinity (varying from strain to strain, ± 90 g.l-1 for
most strains) insufficient quantities of water can be taken up to support the embryo's
metabolism. Optimal salinity for hatching is equally strain-specific, but generally situated in
the range 15-70 g.l-1.
Although the physiological role of light during the hatching process is poorly understood,
brine shrimp cysts, when hydrated and in aerobic conditions, need a minimal light triggering
for the onset of the hatching process, related to light intensity and/or exposure time.