plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111elSSN : 2287-8815
Survival Limits and Physiological and Immunological Responses of theSurf Clam Mactra quadrangularis to Temperature and Salinity Stressunder Simulated Tidal Flat Conditions
전채연1·정희도1,2·김유철1·황운기1·조영관1*
1국립수산과학원 갯벌연구센터, 2국립수산과학원 양식연구과
This study evaluated the survival limits and physiological and immunological responses of the surf clam Mactra quadrangularis under simulated tidal emersion conditions with environmental stressors. Unlike conventional constant- submersion experiments, a tidal cycle simulation was applied: Seawater was fully drained once daily, and clams were exposed to target ground temperatures via infrared irradiation for 4 h, followed by resubmersion. Three stress regimes were tested: Low-temperature emersion (7°C→12, 17, 22°C), high-temperature emersion (25°C→30, 35, 40°C), and low salinity under continuous submersion (6, 8, 10 psu). Under high-temperature emersion, median lethal time (LT50) values were extremely short (4.0, 2.2, and 2.1 days at 30, 35, and 40°C, respectively), while the 7°C→22°C treatment showed an LT50 of 11.4 days. Low-salinity stress also caused rapid mortality (LT50: 3.7 days at 6 psu). The condition index showed no significant change under emersion stress but decreased at 6 psu. Total carbohydrate levels were depleted under high-temperature emersion, whereas protein levels increased markedly in a temperature-dependent manner. The total hemocyte count and phagocytosis rate showed stress-type-specific patterns, including a biphasic immune response and an inverse total hemocyte count (THC)-phagocytosis relationship. These results provide the first quantitative survival thresholds for M. quadrangularis under simulated tidal emersion conditions.
Mactra quadrangularis, Tidal flat, Emersion stress, Survival limit, Physiological responses