管角螺窒息点及昼夜代谢规律

在水温（22±0.5）℃下,按管角螺壳高设置S［（6.48±0.46） cm］、M［（7.59±0.41） cm］和L［（9.08±0.37） cm］3组,研究了管角螺的窒息点及其昼夜代谢规律.结果表明:1）当水中的溶解氧（DO）含量大于临界值4.37 mg·L^-1时,管角螺的耗氧率为1.81 mg·g^-1·h^-1,并处于相对稳定状态;DO低于此值,耗氧率随DO的下降而降低,0.43 mg·L^-1的DO为管角螺的窒息点（耗氧率为0）;2）管角螺的标准代谢（SM）和常规代谢（RM）随体质量的增加而降低,不同壳高处理组昼夜变化规律相同,即夜间代谢强于白天，但不同处理组SM（F=36.263,P＜0.01）和RM（F=6.788,P＜0.01）差异均极显著;S、M和L组特殊动力代谢的峰值分别为2.11、1.62和1.42 mg·g^-1·h^-1,分别为其SM的2.09、1.75和1.71倍,持续时间均为15 h；S、M和L组分别在食后24、24和27 h达到排氨率的高峰,峰值分别为3.94、2.64和1.71 μmol·g^-1·h¹,分别为其饥饿状态下排氨率的1.87、1.73和1.31倍.

Suffocation point and diurnal metabolism pattern of Hemifusus tuba (Gmelin)

The individuals of Hemifusus tuba (Gmelin) were divided into 3 groups, i.e., small ［S, （6.48±0.46） cm］, medium［ M, （7.59±0.41）cm］, and large［ L, （9.08±0.37） cm］, according to their shell height, and their suffocation points and diurnal metabolism patterns were investigated at water temperature (22±0.5) ℃. The results indicated that the oxygen consumption rate of H. tuba was relatively stable and maintained at 1.81 mg·g^-1·h^-1 when dissolved oxygen (DO) content was higher than 4.37 mg·L^-1, but decreased with decreasing DO when DO content was lower than 4.37 mg·L^-1. 0.43 mg·L^-1 of DO was the suffocation point of H. tuba, with the oxygen consumption rate being 0. The standard metabolism (SM) and routine metabolism (RM) of H. tuba decreased significantly with increasing body mass, and changed with the same pattern in the 3 groups,i.e., being higher at night than in daytime. There was a significant difference in the SM (F=36.263，P＜0.01) and RM (F=6.788，P＜0.01) among the 3 groups. The peak values of the specific dynamic metabolism of groups S, M, and L were 2.11, 1.62, and 1.42 mg·g^-1·h^-1, being 1.09, 0.75, and 0.71 times higher than their SM, respectively, and maintained about 15 h. The ammonia excretion rates of groups S, M, and L reached the peak after 24, 24, and 27 hours of feeding, with the peak values being 3.94, 2.64, and 1.71 μmol·g^-1·h^-1, and 0.87, 0.73 and 0.31 times higher than those in starvation state, respectively,.