Effects of Short-Term Salinity Stress on Ions, Free Amino Acids, Na+/K+-ATPase Activity, and Gill Histology in the Threatened Freshwater Shellfish Solenaia oleivora

Salinity is an important ecological factor affecting the osmolality of aquatic animals. Solenaia oleivora endemic and economically freshwater shellfish in China. However, its osmotic response osmoregulatory mechanisms under high salinity stress are still unclear. In this study, S. was exposed to saline water (salinity: 2.2‰) for 3 h, 6 12 24 48 then changes osmolality, ion concentrations, free amino acid (FAA) content, Na+/K+-ATPase (NKA) activity, gill histology were analyzed. The hemolymph increased from h after stabilized between 24–48 h. Na+ stress, Cl− content total FAAs stress. alanine, glycine, glutamine, proline, other NKA activity gill, hepatopancreases, adductor muscle, axe foot decreased during 3–48 filament space number cilia Principal component analysis (PCA) showed that first two principal components (PC1 PC2) cumulatively explained 77.6% variation. positively associated with PC1, while concentration most negatively PC1. Thus, these results indicated osmoconformer, inorganic ions, FAA, NKA, structure play role osmoregulation.