Effects of deep-sea cage culture on water quality and stable carbon and nitrogen isotopes of suspended particulate organic matter in the Yellow Sea Cold Water Mass.

The first submersible cage was launched in the Yellow Sea Cold Water Mass (YSCWM) to culture salmonid. Four cruises were conducted to study the impact of aquaculture activities on the surrounding environment. Results indicated that water quality varied among different sampling times, water layers, and sampling stations. In July and August, low water temperature and high dissolved oxygen concentration were found in the bottom water, which provides a suitable habitat for salmonid culture. Significant correlations were observed between δ13C values in particulate organic matter (POM) and chlorophyll a concentration in June, August, and April. Seasonal and spatial variations of δ13CPOM, δ15NPOM, organic carbon (POC), nitrogen (PN), and C/N in POM were found. Increases in δ13CPOM, POC, PN, decreases in C/N and changes in δ15NPOM around the cage suggested the influence of aquaculture to the environment. However, these influences largely disappear in December.