Physiological, biochemical and molecular responses of Sepia pharaonis juveniles to low salinity

Sepia pharaonis (cuttlefish) has a narrow salinity adaptation range, therefore, it is highly sensitive to changes in salinity. This limits breeding practices for Sepia pharaonis. The aim of this study was to explore effects of low salinity concentrations on gills of cuttlefish. Larvae were randomly categorized into two groups and acclimatized to 2 different salinity conditions (22 psu and 29 psu). Salinity was adjusted by diluting salinity water (29 psu) with fresh water then aeration was carried out overnight. Observation of gills under light and electron microscopy showed that cuttlefish survived up to 22 psu salinity levels. Further, light and transmission electron microscopic examination showed that gills exposed to low salinity stress (22 psu) showed significant pathological changes compared with the control group (29 psu). Biochemical and molecular analyses showed that Na+/K+‐ATPase, Ca2+/Mg2+‐ATPase, TIP4‐1 and Zfand4 were involved in regulation of osmotic pressure in S. pharaonis.