Tank production (2)

Salinity and ionic composition of the culture media

Artemia in its natural environment is only occurring in high-salinity waters (mostly above 100 g.l-1), brine shrimp do thrive in natural seawater. In fact, as outlined earlier (see under 4.1.), the lower limit of salinity at which they are found in nature is defined by the upper limit of salinity tolerance of local predators. Nonetheless their best physiological performance, in terms of growth rate and food conversion efficiency is at much lower salinity levels, i.e. from 32 g.l-1 up to 65 g.l-1.
For culturing Artemia, the use of natural seawater of 35 g.l-1 is the most practical. Small adjustments of salinity can be done by adding brine or diluting with tap water free from high levels of chlorine. Avoid direct addition of sea salt to the culture as to prevent that unsolved salt remains in the tanks. Keep a stock of brine for raising the salinity.

Beside natural seawater or diluted brine, several artificial media with different ionic compositions are used with success in indoor installations for brine shrimp production.

Although the production of artificial seawater is expensive and labour-intensive it may be cost-effective under specific conditions. Sometimes, Artemia grow even better in these culture media than in natural seawater. It is not even essential to use complex formulas since; e.g., Dietrich and Kalle (a media prepared with only ten technical salts) proved to be as good as complete artificial formulas.

Moreover, culture tests with GSL Artemia in modified ARC seawater showed that KCl can be eliminated, and MgCl2 and MgSO4 can be reduced without affecting production characteristics. Calcium concentrations higher than 20 ppm are essential for chloride-habitat Artemia populations whereas carbonate-habitat strains prefer Ca2+ concentrations lower than 10 ppm in combinations with low levels of Mg2+.

Since ionic composition is so important, concentrated brine (not higher than 150 g.l-1) from salinas can also be transported to the culture facilities and diluted with fresh water prior to its use.