温度和盐度对中华圆田螺和铜锈环棱螺标准代谢的影响

利用室内模拟实验研究了环境因子(温度和盐度)对中华圆田螺(Cipangopaludina cathayensis)和铜锈环棱螺(Bellamya aeruginosa)标准代谢的影响。结果表明,在10~35℃范围内,两种螺的耗氧率、CO2排放率和排氨率均随温度的升高而升高,至30℃达到最大值。从Q10值来看,铜锈环棱螺的代谢水平对水温的响应较中华圆田螺更为敏感。呼吸熵和氧氮比结果表明,25℃时两种螺体内的蛋白质消耗最少,由此初步判断二者的最适温度在25℃左右。盐度升高至1.8时两种螺的耗氧率等代谢指标显著提高,同时二者对温度变化的敏感性降低。但从动物呼吸熵和氧氮比的测定结果来看,该盐度下机体仍维持在相对正常的代谢水平。温度和盐度对中华圆田螺代谢活动的影响有显著的交互作用,但对铜锈环棱螺的影响不显著。此外,两种螺的代谢率都存在明显的昼夜变化规律,夜晚的代谢率要显著高于白天。

Influence of water temperature and salinity on standard metabolism of Cipangopaludina cathayensis and Bellamya aeruginosa

Little is known about the biogenetics of gastropods.To address this,we measured the standard meta-bolic rate(SMR) of C.cathayensis and B.aeruginosa at different water temperatures,salinities,and time regimes.We measured SMR every 6 h using the bottle-incubation method.Individuals were incubated at six temperatures(from 10 to 35℃) and two salinity levels(0.3 and 1.8),to simulate saltwater intrusion.The O2 consumption rate,ammonia excretion rate,and CO2 emission rate of the two gastropods were significantly affected by water tem-perature(P<0.01).The body temperature of C.cathayensis and B.aeruginosa varied significantly with changes in temperature and salinity,causing changes in enzyme activity.We calculated the Q10,O:N,and the respiratory using the O2 consumption rate,ammonia excretion rate,and CO2 emission rate.These indices can be used to indicate energy sources in vivo and provide insight into how individuals cope with environmental changes.The ratio of O:N and the respiratory quotient,indicators of protein consumption,were lowest at 25°C suggesting this is the optimal temperature for C.cathayensis and B.aeruginosa.The Q10 values suggest that C.cathayensis is more adaptable than B.aeruginosa to changes in temperature.Increases in salinity were associated with an increase in metabolism(e.g.,O2 consumption and CO2 emission) due to the extra energy required for regulation of ionic equi-librium.The reduced sensitivity towards changes in temperature suggests that these gastropods are minimizing energy consumption during changes in temperature,thus preserving energy for ionic homeostasis.The metabolic activity of C.cathayensis,but not Bellamya aeruginosa,was significantly affected by the interaction between temperature and salinity.The metabolic rate of both gastropods fluctuated diurnally,being higher during the night.This likely reflects the diurnal pattern of activity in both species,which tend to feed and compete for dissolved O2 during the night.