Effects of hypoxia on osmotic and ionic regulation in the brown shrimp Crangon crangon (L.) from brackish water

When exposed to hypoxia (P_wO₂, <P_cr) and low salinity conditions, the shrimp, Crangon crangon (L.) shows a progressive loss of blood chloride until a new, stable value, still higher than that of the medium, is reached. Simultaneously, circulating levels of calcium progressively increase. Under identical experimental conditions, circulating levels of sodium and magnesium and the blood total osmolarity (Δ °C) are unchanged. The possible explanations for such changes are considered along with their adaptive significance.