南澳贝藻混养互利机制的初步研究

以牡蛎和龙须菜为试验材料,进行了两个阶段不同投放比例的室内模拟混养试验,试验周期均为4周,各试验组分别为:对照组、龙须菜单养组、牡蛎单养组、牡蛎龙须菜低密度混养组、牡蛎龙须菜中密度混养组和牡蛎龙须菜高密度混养组,其中除对照组和龙须菜单养组外,各试验组牡蛎密度均为27只/m3,第一阶段龙须菜密度分别为:0,47,0,47,94,188g/m3,第二阶段龙须菜密度为:0,158,0,158,316,854g/m3。定期采样测定水体中营养盐(NO2-N,NO3-N,NH4-N,PO4-P)的含量及养殖生物的生长情况。试验结果表明,第一阶段试验结束时,投放牡蛎的试验组与未投放牡蛎的试验组水体氮、磷含量差异显著(P0.05)。第二阶段试验结束时,投放牡蛎的各试验组磷酸盐和硝酸盐含量差异显著(P0.05),高密度混养组的磷酸盐含量和硝酸盐含量与牡蛎单养组相比分别降低了43%、30%,说明龙须菜明显吸收了水体中的氮、磷,混养系统氮、磷利用更为合理,其中龙须菜854g/m3,牡蛎27只/m3的高密度混养组投放密度最为合理。

Mutually Beneficial Mechanism in Nanao Polyculture of Oyster(Crassostrea gigas) and Kelp(Gracilaria lemaneiformis) in Nanao, Guangdong Province

Two polyculture trials were conducted in a tank to evaluate the mutually beneficial mechanism in the polyculture of kelp Gracilaria lemaneiformis with oyster.In the polyculture,the kelp and the oyster were separately cultured as control groups,and polucultured at low,middle,and high densities.In the first 4-week trial,the oyster were reared at a density of 27 individuals/m3,and the kelp were cultivated at a density of 0,21,0,21,42,or 84 g/450 L,but 0,71,0,71,142,or 384 g/450 L in the second 4-week trial.During the experiment,the concentrations of NO3-N and PO4-P,survival and growth of the oyster and kelp were detected every 7 days.It was found that there were significantly lower NO3-N and PO4-P levels in the tanks with oyster than in the tanks without oyster in the first trial(P<0.05).In the second trial,however,the concentrations of NO3-N and PO4-P in the tanks with oyster were significantly different from those in the tanks without oyster(P<0.05).There were 43% lower NO3-N level,and 30% lower PO4-P level in the high density groups than those in the monoculture of the oyster,indicating that the kelp absorbed the nutrients from the co-culture groups at an optimal density of 27 oyster,and 384 g kelp/m3.