Salinity levels that trigger and affect carbonic anhydrase increase in the gills of two salt-tolerant crab species

At a critical salinity of 27 ppt, carbonic anhydrase activity approximately doubles in the gills of two crustacean species.

• All gills of Carcinus maenas and Callinectes sapidus exhibit uniformly low carbonic anhydrase activity at high salinity.
• CA induction occurs in the posterior gills, which are responsible for ion transport, when salinity decreases to 27 ppt.
• Changes in CA activity can be triggered by salinity alterations as minor as 20 milliosmoles.
• A critical exposure time of 48-72 hours in C. maenas and 12 hours in C. sapidus is required for CA induction to begin.
• Once CA induction starts, it persists despite subsequent salinity changes, potentially as a metabolic adaptation.

Simplified