Comparison of blood physiological parameters between three species of scallops and the effect of heat stress on blood physiological parameters in Chlamys farreri

Blood physiological parameters reflect the acid-base balance status and oxygen supply of organism by the ion concentration and partial pressure of gas in blood, and play an important role in the animal physiology and pathology. In order to compare three scallop species in terms of blood concentrations of K⁺, Na⁺, Ca²⁺ and Cl⁻, partial blood pressures of O₂ (pO₂) and CO₂ (pCO₂), and blood acidity (pH), a blood gas analyzer was used to measure the blood physiological parameters of Chlamys farreri, Patinopecten yessoensis and Argopecten irradias. The results revealed that there were significant differences in blood physiological parameters between different species of scallops. Specifically, the values of K⁺ (15.74±1.47) mmol/L, Na⁺ (388.07±11.38) mmol/L, Cl⁻ concentrations (462.43±6.88) mmol/L and pO₂ (140.13±15.35) mmHg were higher in the blood of C. farreri than other two scallops. The values of Ca²⁺ and pCO₂ of P. yessoensis and C. farreri were higher than those of A. irradias, and the pH of A. irradias was highest among the three scallops. In addition, the blood pH of C. farreri was significantly positively correlated with shell height (r=0.611, P<0.05), while other physiological parameters were negatively correlated with it. With the increase of temperature, the concentration of Ca²⁺ increased significantly in the blood of C. farreri while pO₂ decreased significantly. During the temperature change, the concentrations of K⁺, Na⁺ and Cl⁻ in C. farreri increased firstly and then recovered to the initial levels, while the values of pH and pCO₂ remained relatively stable. The results provide basic information for blood physiology research and a new approach to the assessment of the physiological states of bivalves.