Assessment of Ecosystem Energy Flow and Ecological Capacity of Apostichopus japonicus in the Furong Island Artificial Reef, Laizhou Bay

The fishery resources in the Furong Island, Laizhou Bay artificial reef were investigated in 2019; the energy flows and structure of the ecosystem were modeled, and the ecological capacity of Apostichopus japonicus was estimated using an Ecopath with Ecosim 6.6 (EwE 6.6). The model included 16 functional groups that covered the main processes of energy flows in the Furong Island artificial reef ecosystem. According to the results, the trophic levels of the functional groups varied from 1.000 to 3.978; Lateolabrax maculatus occupied the highest trophic level. The total transfer efficiency was 10.6%, and the proportions of the total flow originating from primary producers and detritus were 10.8% and 10.1%, respectively. The total system throughput was estimated to be 2 596.108 t/(km2·a), with 44% originating from detritus. The ratio between the total primary productivity and the total respiration of the system was 1.454; the connectance index was 0.402; the system omnivory index was 0.211; and the Finn cycling index and Finn mean path length were 8.860% and 2.980, respectively. The results showed that the Furong Island artificial reef ecosystem was at a relatively low maturity and stability level with a relatively simple food web. The ecological capacity of A. japonicus estimated by the model was 131 t/km2, which is 6.55 times the existing stock, indicating its growth potential. According to the actual production situation, the ecological balance of the ecosystem can be maintained with an annual catch of 4.1 t/km2. At present, there are few studies using the Ecopath model to evaluate the ecological consequences or ecological capacities of artificial reefs, in China or abroad, and there is little discussion about fishery management models. More applications and verification on artificial reefs are required. This study is expected to provide a scientific basis for the evaluation of ecological consequences of artificial areas and the sustainable utilization of marine ranches.