Impact of shellfish biodeposits and rotten seaweed on the sediments of Ailian Bay,China

We assessed the function of a Patinopecten yessoensis and Saccharina japonica integrated multi-trophic aquaculture (IMTA) model on the level of organic matter produced in the environment. The study was conducted in March–July 2012 using stable carbon and nitrogen isotope methods. Results showed that the quantity of rotten kelp increased considerably over these 5 months, with the length of the rotten blades reaching 150 cm in July. The contribution rates of biodeposits by the shellfish and kelp to the suspended particulate matter (SPM) were 3.93 ± 0.39 and 4.99 ± 1.09 %, respectively, but contribution rates to the sediments in the IMTA area were very low. In May and July, rotting kelp contributed 1.06 ± 0.46 and 1.64 ± 0.13 % in the kelp area, respectively. The organic carbon and nitrogen content of sediments from the IMTA area was significantly higher than from the kelp area (P < 0.05). C% and N% in SPM from the IMTA area were four times those from the kelp area (P < 0.05), but the C and N content in sediments were still at a low level.