Abstract: By the method of land-based enclosure, three kind organisms including fish (Sparus macrocephlus), seaweed (Gracilaria lichevoides), and benthos (Perinereis aibuhitensis) were selected to construct four kinds of mariculture models, i.e., S. macrocephlus (F), S. macrocephlus + G. lichevoides (FG), S. macrocephlus + P. aibuhitensis (FP), and S. macrocephlus + G. lichevoide + P. aibuhitensis (FGP) to study the removal of nitrogen (N), phosphorus (P), and particulate organic matter (POM) in water body and sediment, and to analyze the environmental effect of each mariculture model, aimed to approach a clean mariculture model in land-based enclosure. Among the four mariculture models, culturing fish with 1.5 kg·m^-2 of seaweed and 22.5 kg·hm^-2 of benthos had better effects in purifying water body and sediment, and effectively increased the harvested fish yield. The seaweed could effectively remove the dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) in water body. The models with seaweed had significantly lower concentrations of N and P in water bodies, compared with the models without seaweed (P<0.05), but no significant differences were observed between treatments FG and FGP and between F and FP. The benthos could remove the POM in the sediment, and the models with benthos had lower concentrations of N and P in the sediment. Especially in the sediment layers 1-2 cm and 2-4 cm, the N and P concentrations in the models with benthos were 7% and 9% lower than those in the models without benthos, respectively (P<0.05). Furthermore, the models with seaweed or/and benthos had higher fish yield, compared with fish monoculture model (P<0.05), and the fish yield in treatment FGP was 57% higher than that in treatment F. To have an integrative consideration, culture model FGP had the optimal environmental, economic, and comprehensive benefits.

Key words: Phragmites communis, Clone plant, Ramet, Biomass allocation, Heterogeneous speed growth