AUTHOR=Hao Yu , Sun Chunyang , Rong Yun , Wang Haiqing , Xu Qiang , Gao Fei , Wang Aimin 

TITLE=Circulatory and Metabolic Physiology Disorder in Different Organs of the Subtropical Scallop Species Chlamys nobilis Under Thermal and Hypoxia Stress, Revealed by Doppler Ultrasonography Technique

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.880112

DOI=10.3389/fmars.2022.880112

ISSN=2296-7745

ABSTRACT=Due to the impact of climate change and human activities, low oxygen events in the ocean occur frequently. As an important economic shellfish, mass mortalities of noble scallop Chlamys nobilis often occurred under hypoxia stress. The circulatory physiological indexes of scallops under different hypoxia stress (oxygen concentration: 4 mg/L, 3 mg/L, 2 mg/L) were monitored by the Doppler ultrasonography system. It was found that the peak systolic velocity (PS) and heart rate (HR) increased to varying degrees in the phase of dissolved oxygen decline，while the end diastolic velocity (ED) of scallops was less affected by hypoxia. And the blood flow of different organs was more affected with the decrease of oxygen concentration. There was no significant change in blood flow volume at 4 mg/L and 3 mg/L DO, but the blood flow of scallops significantly decreased at 2 mg/L DO. The metabolism of scallops changed from aerobic metabolism to anaerobic metabolism under low oxygen., which was confirmed by increased PK activity. However, but scallops still maintained a certain aerobic metabolism capacity and the significant expression of COX at 6 h proved that the aerobic metabolism capacity of scallops was improved. Glycogen consumption in muscle was not significant under hypoxia. At the end of the experiment, ATP accumulation in gill and mantle indicated that the scallop had returned to the normal body energy supply state. The relationship between physiological regulation and metabolic regulation needs further study. Our study provides a new method for exploring the circulation physiology of bivalves. Doppler ultrasonography system has made the study of scallop circulatory physiology more comprehensive, and our study supplement the data related to the metabolic regulation of bivalves under hypoxia. It is important to study the self-regulation mechanism of bivalves in response to hypoxic events, which can make important contributions to the protection of nearshore shellfish resources.