Effects of dissolved oxygen concentration on behavior, antioxidant enzyme activities and tissue structure of whelk Neptunea cumingii Crosse
ZHANG Qianhong, WANG Shaojun, TIAN Ying, WANG Luo, MAO Junxia, WANG Xubo,WANG Qingzhi, CHANG Yaqing, HAO Zhenlin*
1.Key Laboratory of Mariculture & Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian 116023, China; 2.Shandong Fishery Development and Resource Conservation Station, Jinan 250013, China; 3. Liaoning Ocean and Fisheries Science Research Institute, Dalian 116023, China
Abstract: In order to explore physiological and ecological effects and to clarify the adaptation mechanism of whelk Neptuneacumingii Crosse under different levels of dissolved oxygen (DO), the behavioral characteristics, histopathological damage in gill and olfactory tissue and antioxidant enzyme activity were investigated in the whelk with body weight of (85.3±9.3)g exposed to DO concentrations of 0, 2, 4, 6 and 8 (control) mg/L. The behavioral states of the whelk was divided into 4 types: normal state (less movement and long-term static adsorption), active state (short resting time, and long movement time), desorption state (foot edema), and death state (soft body part cannot be fully retracted into the shell). The whelk crawled actively and fed less when DO concentration was decreased, stopped feeding and death occurred at DO≤4 mg/L. Histological observation showed that the gap between gill filaments and the number of gill mucus cells were increased first and then decreased with the decrease in DO concentration. The top of gill filaments expanded, the respiratory epithelial cells fell off, and the surface cells sagged and formed folds, sometimes the gill filament was broken; the number of mucus cells was increased first and then decreased in osphradium with the decrease in DO concentration, without significant change in cell structure. The total antioxidant capacity (T-AOC) and activity of superoxide dismutase (SOD) in gill and hepatopancreas were shown to be decreased firstly, then increased and then decreased with the decrease in DO concentration, and the activity of CAT in gill to be increased first and then decreased. The activity of CAT in hepatopancreas was positively correlated with DO concentration. It was found that 6 to 8 mg/L of DO concentrations was the optimal or the whelk adapted to the hypoxic environment stress by changing behavior and related organizational structure, as well as regulating. The whelk was dead at DO≤4 mg/L for≥96 h.
2022, Vol. 37 
