Summer deoxygenation in a bay scallop (Argopecten irradians) farming area: The decisive role of water temperature, stratification and beyond

Abstract

During 2015–2020, 26 cruises were carried out in a bay scallop farming area, North Yellow Sea, to study the dissolved oxygen (DO) dynamics and its controlling factors. Significant DO depletion (deoxygenation) was observed in the summertime with the decrease rates of 0.31–0.55 and 0.96–2.10 μmol d−1 in the surface and bottom waters, respectively, which were comprehensively forced by temperature, photosynthesis and microbial respiration. Seasonally, temperature was the main driver of the deoxygenation processes. In the surface water, DO dynamics were dominated by temperature-induced solubility changes, while the photosynthesis offset the effects of physical processes to a certain extent; in the bottom water, its dynamics were mainly attributed to the comprehensive control of temperature-induced solubility changes and biological respiration. Overall, the results suggested that the occurrence of hypoxia and acidification in the coastal waters were highly associated with the formation of temperature-induced stratification under complex hydrodynamic processes.