不同温度对硬头鳟幼鱼C、N、P营养要素收支的影响

Effects of Temperature on the C,N,P Nutrient Budgets of Juvenile Steelhead Trout(Oncorhynchus mykiss)

本实验模拟了硬头鳟海水网箱养殖周期内的温度变动范围,研究了不同温度对硬头鳟(Oncorhynchus mykiss)幼鱼碳(C)、氮(N)、磷(P)营养要素收支的影响。实验选取体重为(150.27±22.90)g的硬头鳟幼鱼为研究对象,采用4个温度条件(9、13、16和19℃)进行培养,测定了不同温度处理组内硬头鳟幼鱼C、N、P营养要素的收支情况。研究表明:温度对海水环境中硬头鳟幼鱼的C、N、P营养要素收支具有显著影响(P<0.05)。硬头鳟幼鱼的摄食率、排粪率、排氨率和排磷率在9℃处理组中分别为0.699mg·g^(-1)·h^(-1)、0.099mg·g^(-1)·h^(-1)、4.154μg·g^(-1)·h^(-1)和0.435μg·g^(-1)·h^(-1),显著低于其他处理组;在16℃处理组中,达到最大值,分别为1.118mg·g^(-1)·h^(-1)、0.150mg·g^(-1)·h^(-1)、7.173μg·g^(-1)·h^(-1)、0.577μg·g^(-1)·h^(-1)。硬头鳟幼鱼的耗氧率在低温环境中随温度的上升增加显著,耗氧率(OR)与温度(T)之间的变化规律符合方程OR=-0.816 2T2+33.224T-28.689(R2=0.798 5)。C、N、P营养要素的生长余力在9℃处理组中分别为0.213、0.036和0.008mg·g^(-1)·h^(-1),显著低于其他处理组;在16℃处理组中,达到最大值,分别为0.353、0.058和0.010mg·g^(-1)·h^(-1)。19℃处理组中,C、N营养要素的吸收效率分别为63.48%和82.56%,显著低于其他3个处理组;P营养要素的吸收效率为75.47%,显著低于16℃处理组。高温环境对硬头鳟幼鱼的营养要素收支会产生不利影响,网箱养殖过程中,水温过高时,应通过减少投喂并增加曝气的方式降低鱼体死亡的风险。

The present experiment simulated the temperature fluctuation during the culture period of steelhead trout(Oncorhynchus mykiss)in seawater to examine the effects of different temperatures on the budgets of C,N and P nutrients.Juvenile steelhead trout with weights of(150.27±22.90)g were cultured at 9,13,16 and 19℃in seawater and the processes of C,N and P budgets were examined.The results showed that C,N,P nutrient budgets of steelhead trout were significantly different between 4 temperatures(P<0.05).At 9℃,the feed uptake,fecal production,ammonium excretion and phosphorus excretion rates of juvenile steelhead trout were 0.699 mg/h,0.099 mg/h,4.154μg/h and 0.435μg/h,respectively,significantly lower than those of other groups(P<0.05).Feed uptake,fecal production,ammonium excretion,phosphorus excretion rates of the fish maximized at 16℃,being 1.118 mg·g-1·h-1,0.150 mg·g-1·h-1,7.173μg·g-1·h-1,0.577μg·g-1·h-1,respectively.The oxygen consumption rate(OR)increased with temperatures(T),following the formula OR=-0.816 2 T 2+33.224T-28.689(R 2=0.798 5).The scope for growth(SFG)of C,N and P of juvenile steelhead trout was 0.213 mg·g-1·h-1,0.036 mg·g-1·h-1 and 0.008 mg·g-1·h-1,respectively,significantly lower than that of other groups(P<0.05),which maximized at 16℃,being 0.353 mg·g-1·h-1,0.058 mg·g-1·h-1 and 0.010 mg·g-1·h-1,respectively.The absorption efficiency of C and N of juvenile steelhead trout was 63.48%and 82.56%at 19℃,respectively,significantly lower than that of other 3 groups.The absorption efficiency of P at 19℃was 75.47%,significantly lower than that at 16℃.Nutrient budgets of juvenile steelhead trout were vulnerable to negative effects of high temperature.In net cage trout farming,administrators could reduce feeding and increase the supply of oxygen thus reduce the death rate of trout at high temperature.