Practice assessment of integrated marine pond aquaculture for increasing benefits and reducing environmental pollution using an ecosystem modeling approach.

The transformation from semi-intensive and intensive aquaculture to integrated aquaculture is an effective way to upgrade the aquaculture process. Integrated aquaculture is better able to maintain a healthy environment and a balanced ecosystem for the cultured species as well as producing high quality commodities at a high yield. In this study, we demonstrate that ecosystem modeling can be used to help optimize and promote the integrated aquaculture model. First, the aquaculture management and main biochemical processes were parametrized according to the biological populations present, the physical environment, and the management practices for the integrated aquaculture marine pond of Portunus trituberculatus- Penaeus japonicus- Sinonovacula constricta. The ecosystem model of the pond unit was constructed by coupling the individual growth models of the three cultured animals. The goodness-of-fit indicators showed that this model accurately reproduced the dynamics of the cultured animals, plankton, and nutrients. After the ecosystem model was constructed and validated, the carrying capacity of the integrated aquaculture pond was evaluated by adjusting the stocking density and management practices based on the tailwater discharge standards. The economic benefits of the system and the ecological benefits of polyculture razor clams were quantitatively compared under two scenarios: the current stocking density and reaching the maximum capacity. The assessment results show that the aquaculture pond reached the carrying capacity when the stocking density was 1.8 times the current scenario (18 ind m, 27 ind m, 22 ind m for P. trituberculatus, P. japonicus and S. constricta). At 1.8 times stocking density scenario, the profit increased by 51.59 %, and nitrogen and phosphorus removal increased by 51.48 % and 55.55 %, respectively. These results provide a theoretical basis for this integrated aquaculture model, which offers a promising way forward for sustainable industrial development. Possible applications and beneficial contributions of this aquaculture model in China are discussed.