Natural sedimentation in large-scale aquaculture areas of Sungo Bay, north China Sea

CAI Lisheng1, FANG Jianguang2, LIANG Xingming2(1. Fisheries College, Ocean University of China, Qingdao 266003, China;, Qingdao 266071, China)

natural sediments; TN; TP; P/N ratio; molluscan culture area

Sungo Bay is located to the east of Shandong Peninsula where scallop, oyster and kelp have been cultured in large scale for many years. The experiment was conducted in five periods from September 2001 to July 2002. The scallop, oyster and kelp culture areas were chosen as the experiment spots, and in each spot 3×3 sediment traps were set to collect the falling particulate matter. The concentrations of TN,TP and POM in the particulate matter both from the traps and the sediments of the experimental areas were measured. The results showed that the yearly average sedimentary rate of particulate matter was 278.8 g/(m2.d) in the areas, and 190.4 μg of TN,472.5 μg of TP and 0.103 g of POM in per gram of the particulate sediments were carried down to the bottom. There was an obvious seasonal variation in terms of TN and TP contents in the particles that the peak value of the TN content appeared in May, and the bottom value appeared in December, while the value of TP content was higher in cold season (December) than in warm season (May, July). The N/P ratio of the sinking sediments ranged 0.67-2.0, but that in the sediments was in the range of 0.025-2.0. The purpose of this experiment is to provide a field basis for the studies of the nutrient flux and the carrying capacity of shallow sea aquaculture.