贝类对对虾养殖池塘沉积物中小型底栖动物的影响

通过分析凡纳滨对虾单养及其与泥蚶混养实验的沉积物的理化特性、小型底栖动物种类组成及其生物量的变化,研究贝类对对虾池中小型底栖动物的影响。实验中对虾放养密度均为17×10~4个/hm~2,泥蚶密度分别为0粒/m~2(S)、60粒/m~2(SC1)、120粒个/m~2(SC2)和180粒/m~2(SC3)。结果显示,随养殖时间增加:(1)沉积物中有机物含量呈上升趋势,pH与氧化还原电位逐渐下降;随贝类放养密度增加,底质环境恶化程度趋缓;(2)小型底栖动物的丰度和生物量呈下降趋势,随着贝类放养密度增加,小型底栖动物的群落结构变化逐渐减少;(3)回归分析表明,介形类与线虫比值与对虾产量呈较好的相关性,一定密度贝类混养有利于底泥中介形类与线虫比值的提高,初步结果为养殖过程中该比值平均要达到6,单次值不低于3.5。研究表明,对虾与泥蚶混养有利于底质的改善和小型底栖动物的生长,较高密度的泥蚶(80~140个/m~2)有明显净化底质的作用。

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,organic 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.The abundance and biomass of meiofauna showed a downward trend;community structure of meiofauna was more stable with the increase of bivalve stocking density.Regression analysis showed that the ratio of ostracoda to nematodes had obviously positive correlation with the shrimp yield.A certain density ofpolyculture 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.