Effect of bivalve on meiofauna in the shrimp culture pond

To study the effect of bivalve on meiofauna in shrimp ponds, physical and chemical characteristics of sediment, abundance and biomass of meiofauna were analyzed both in monoculture and polyculture of shrimp (Litopenaeus vannamei) with bivalve (Tegillarca granosa). Four treatments with different stocking density of bivalve 0 ind/m² (S), 60 ind/m² (SC1), 120 ind/m² (SC2), 180 ind/m² (SC3) were designed, and each treatment was stocked with 17×10⁴ ind/hm² of shrimp. The results showed that, with the increase of culture time, ①organic matter content showed an upward trend. pH value and ORP were gradually decreased; increase of bivalve stocking density is beneficial to slowing the progression of the deterioration of sediment environment. ② The abundance and biomass of meiofauna showed a downward trend; community structure of meiofauna was more stable with the increase of bivalve stocking density. ③ Regression analysis showed that the ratio of ostracoda to nematodes had obviously positive correlation with the shrimp yield. A certain density of polyculture with bivalve was conducive to increasing the ratio of ostracoda to nematodes. A preliminary result showed that, to have a good yield, the average ratio was better to reach 6 during shrimp culture, and a single value was not less than 3.5. Therefore, shrimp polyculture with bivalve was conducive to sediment quality improvement and can increase growth of meiofauna, and higher density (80–140 ind/m²) of bivalve had a clear function of purification of the sediment.