Abstract:In recent years, environmental pollution and ecological problems caused by cage aquaculture have become increasingly prominent in shallow seas. The cultivation technique of integrated multi-trophic aquaculture (IMTA) can be applied to minimize the impact of nutrient enrichment from organic fisheries. The IMTA mode was implemented in September to November 2018 in this study, which included fish cage aquaculture, the shellfish Pinctada martensi, and the alga Eucheuma striatum. The feeding physiology indicators of P. martensi and the nutrient uptake rate of E. striatum were measured at different temperatures in the laboratory concurrent with conducting field experiments, and the improvement of the water quality in the cage aquaculture area by IMTA of shellfish and algae were compared and analyzed. The results showed that: (1) the specific growth rate (SGR) of P. martensi in the marine fish cage area was significantly higher than that in control area, and the average shell height of P. martensi in the 0.50~0.62 m water layer in the cage area was significantly higher than the other water layers. (2) Eucheuma striatum had the fastest SGR in the 0.60~0.90 m water layer, and the net wet weight gain of E. striatum was significantly higher than that in the control area. (3) At 24.45℃, the average feeding rate, absorption rate, and absorption efficiency of P. martensi on particulate organic matter were, respectively, (4.13±0.77) mg/h·ind., (1.04±0.24) mg/h·ind., and (25.00±2.51)%, which were significantly higher than those at 20.74℃. Within the experimental temperature range, the absorption rates of nitrogen, phosphorus, and silicon first increased then decreased with increasing temperature, and the maximum values appeared at 30℃. (4) It is estimated that the total amount of filtered particulate organic matter and the total amount of absorbed particulate organic matter by P. martensi in the marine fish cage area during the culture experiment was 778.08 g and 144.47 g, respectively, and the total amount of nitrogen, phosphorus, and silicon removed by E. striatum in the marine fish cage area was 8.55 g, 1.11 g, and 9.18 g, respectively; all the above indicators were higher than those in the control area. Temperature, depth of cultivation, particulate organic matter, and nutrient concentrations were the primary factors affecting the growth and physiological metabolism of P. martensi and E. striatum. This study provides data and theoretical support for the establishment of IMTA technology.
