pH、温度对缢蛏碳收支的影响

Effects of pH and temperature on carbon budget of Sinonovacula constricta

本文以缢蛏(Sinonovacula constricta)为实验对象,研究了在不同温度、pH梯度下碳代谢情况,测定其摄食、呼吸、排粪和排泄等生理参数,并根据能量平衡原理估算了缢蛏的碳收支情况。结果表明:缢蛏从球等鞭金藻(Isochrysis sphaerica)中摄取的有机碳源主要通过呼吸代谢消耗、以粪便的形式排出,少部分随排泄代谢产物流出,余下的碳主要用作贝类自身的生长;在温度为23℃,pH值8.2时缢蛏对碳的利用率大于pH 7.6、7.9时对碳的利用率;在pH值8.2,温度在15~31℃范围内,缢蛏对碳的利用率出现先增高后降低的变化趋势;单因素方差分析表明,低pH和温度均显著影响缢蛏摄食率(P<0.05),温度为23℃时,随着pH的降低,缢蛏对球等鞭金藻的摄食率呈下降趋势;pH值8.2时,摄食率在15~31℃范围内呈先增高后降低的变化趋势。低pH和温度对缢蛏的耗氧率存在显著影响(P<0.05),温度为23℃时,随着pH的降低,缢蛏的耗氧率呈下降趋势;pH值8.2,缢蛏的耗氧率在15~31℃范围内呈先增高后降低的变化趋势。低pH、温度对缢蛏的排氨率和排粪率均不存在显著影响(P>0.05)。

The purpose of this study was to estimate the effects of seawater acidification and ele- vated temperature on the carbon budget of clam Sinonovacula constricta. Adult clams were ex- posed to various treatments under conditions of three pH values and three temperatures. The in- gestion, respiration, defecation, and excretion of S. constricta were detected. The results showed that the carbon source obtained by S. constricta was mainly consumed through breathing, and then they were directly discharged as dejection, with a small part being discharged by excretion. The remaining carbon was mainly used for growth and development. At 23 ℃, the utilization rate of carbon at pH 8.2 was greater than that at pH 7.6 and pH 7.9. In pH 8.2 seawater, the utilization rate of carbon reached the peak at 23 ℃ when the water temperature ranged from 15 ℃ to 31 ℃. One-way ANOVA showed that the ingestion rate was significantly influenced by low pH and tern- perature （P〈0.05）. In 23 ℃ seawater, with pH declining, S. constricta fed less Isochrysis spha- erica. At pH 8.2, the ingestion rate reached the peak at 23 ℃ when temperature changed from 15 to 31 ℃. Moreover, the oxygen consumption was significantly influenced by low pH and tempera- ture （P〈0.05）. In 23 ℃ seawater, the respiration rate declined with pH decreasing. At pH 8.2, the respiration rate reached the oeak at 23 ℃ when the temnerature raned from 15℃ to31 ℃However, no significant differences in excretion rate and defecation rate under low pH and tem- perature were found in this study （P〉0.05）.