Multiple sources state that brine shrimp are smaller in highly salty water and larger in less salty water. Also, salinity levels also affect the rate of sexual development. Higher salinities produce adults who reach maturity quicker, but are shorter in length. Baid (1963) also determined that as salinity increases, the abdomen becomes longer relative to body length. Unpublished observations by DWR biologists show they have longer thoracopods, and a longer tail in hypersaline water.
High salinity results in offspring that develop quickly but are smaller and have a relatively longer abdomen.
Research has shown that the maximum salt tolerance for adults is around 30% salinity, which is near the saturation level of 28%. Optimal levels for cyst production are 14%-17%. For reference, most seawater is around 3-4%. Low salinity levels tend to cause cysts to crack prematurely, which may partially explain the influence of spring runoff in hatch timing. Low salinities also allow other competitors to invade areas that were once unsuitable and can alter phytoplankton composition and interrupt food chains.
Low salinity may cause cysts to crack prematurely, as well as allowing other competitors into the ecosystem.
Artemia require 10% salinities, or less, to initiate hatching. Generally, spring runoff and precipitation lower surface salinities to these levels, but cysts in higher salinities must float in order to take advantage of surface precipitation. Within the GSL, cysts found in water of 16-28% salinity had a lower density than those found in the 10-14% range, causing them to float to the surface where less salty water would be found. Water with 28% salinity is at saturation, and the maximum concentration. Cysts sink in water that is 0-8% saline, which may be advantageous, because salinity increases with depth (this is seen in the Mono Lake, CA population, as the salinity of that lake falls in this range).
Brine shrimp have evolved a density mechanism so that cysts place themselves in the most advantageous salinity concentration.Quiz Time: Name 3 effects of salinity on brine shrimp