盐度对中华绒螯蟹雌性亲蟹代谢的影响

测定了不同盐度(0,6,12,18,24)条件下,中华绒螯蟹(Eriocheir sinensis)雌性亲蟹的耗氧率、CO2排出率及NH3 N排泄率,并研究了其呼吸熵、氧氮比、代谢率及能源物质供能比随盐度的变化情况。结果表明,体质量为(55.59±6.24)g的中华绒螯蟹雌性亲蟹,在水温(16±1)℃条件下,盐度对其耗氧率及NH3 N排泄率影响显著(P<0.05)。在实验盐度范围内(0~24),其耗氧率及NH3 N排泄率均随盐度的升高而下降,CO2排出率及代谢率的变化趋势与耗氧率一致,且盐度为6的实验组亲蟹CO2排出率及代谢率均与对照组差异不显著(P>0.05),在盐度12~24范围内,亲蟹CO2排出率及代谢率均显著低于对照组(P<0.05);呼吸熵及氧氮比均变化不显著(P>0.05);能源物质以脂肪的供能比例最大,其次是碳水化合物,蛋白质的供能比例最小。分析认为,中华绒螯蟹雌性亲蟹在生殖洄游过程中主要以脂肪作为供能物质,代谢率与能量消耗逐渐降低。

Effect of salinity on the metabolism of female Chinese crabs, Eriocheir sinensis

We evaluated the effect of salinity on the metabolism of female Chinese crabs(Eriocheir sinensis).The crabs,body weight(55.59 ± 6.24) g,were held at salinities of 0,6,12,18 and 24,(16 ± 1)℃,and we measured oxygen consumption,CO2 production,and ammonia-N excretion.Using this data,we calculated the respiratory quotient,oxygen-nitrogen ratio,energy consumption rate,and metabolic substrate ratio.Salinity had a significant effect on the oxygen consumption rate and ammonia–N excretion rate(P<0.05).Between salinity 0–24,the rates of oxygen consumption and ammonia–N excretion both decreased as salinity increased.We observed a similar pattern for CO2 production and energy consumption,but the differences were not significant relative to the control group at salinity 6(P>0.05).Between salinity 12–24,CO2 production and energy consumption were significantly lower than in the control group.Salinity had no effect on the respiratory quotient and oxygen–nitrogen ratio(P>0.05).Our results suggest that lipids are used preferentially as an energy source.Furthermore,proteins were utilized to a much greater extent than carbohydrates.The proportion of lipids in the metabolic substrate increased as salinity increased.Conversely,the carbohydrate metabolic substrate ratio decreased as salinity increased,whereas the protein metabolic substrate ratio remained constant.At salinity 24,the ratio of protein,carbohydrate,and lipid used as metabolic substrate was 6.4:14.6:79.0.During the reproductive migration,the female Chinese crab migrates from fresh water into the Yangtze River estuary.Thus,individuals must adjust to the higher salinity and modify their energy metabolism.Our results suggest that energy consumption decreases after entering salt water,allowing female crabs to divert energy into reproduction.