A study of organic carbon, nitrogen and phosphorus budget in jellyfish-shellfish-fish-prawn polyculture ponds

摘要

A budget describing the flow of organic carbon (OC), nitrogen (N) and phosphorus (P) through two polyculture ponds (jellyfish-shellfish-fish-prawn) was constructed. The total input of OC was 3107kgha(-1) in pond 1 and 3358kgha(-1) in pond 2, while total output was 1759kgha(-1) in pond 1 and 1325kgha(-1) in pond 2. In pond 1, the total input of N was 364kgha(-1) and output was 359kgha(-1), whereas, in pond 2, the total input of N was 439kgha(-1) and total output was 331kgha(-1). The total input of P was 75kgha(-1) in pond 1 and 66kgha(-1) in pond 2, while total outputs for pond 1 and pond 2 were 74 and 65kgha(-1) respectively. Primary production from phytoplankton contributed the largest proportion of total OC (49-56%), while feed contributed the largest proportion of N (78-81%) and P (79-80%). Animals harvested from the aquaculture ponds accounted for the largest proportion of N (50-73%) and P (49-52%), and respiration accounted for the largest proportion of OC (43-61%) output from the system. The OC, N and P use efficiency of harvested animals was 30.30%, 70.19% and 50.14% in pond 1, respectively, and 21.03%, 46.95% and 46.47% in pond 2 respectively. In terms of nutrient use, the filter-feeding bivalve, Sinonovacula constricta, was the most efficient species within the polyculture system.