海水酸化胁迫对紫贻贝能量分配的影响

Impact of seawater acidification on the energy budget of Mytilus galloprovincialis

中文关键词: 海洋酸化  紫贻贝  摄食  代谢  桑沟湾

英文关键词: Seawater acidification  Mytilus galloprovincialis  Feeding  Metabolism  Sanggou Bay

中文摘要:

      2016年5~6月在山东桑沟湾楮岛海区，采用野外围隔和现场流水相结合的方法，以紫贻贝(Mytilus galloprovincialis)为研究对象，以pH为8.0作为对照组，探讨了酸化胁迫(pH=7.7)对其能量分配的影响。结果显示，短期(10 d)海水酸化胁迫下，紫贻贝的滤水率、同化效率、氧氮比显著下降(P<0.05)，排氨率极显著增加(P<0.01)，耗氧率无显著差异(P>0.05)；中期(30 d)海水酸化胁迫下，紫贻贝的滤水率和氧氮比显著下降(P<0.05)，而同化效率、耗氧率、排氨率显著升高(P<0.05)。能量收支的结果显示，短期(10 d)酸化胁迫下，紫贻贝的摄食能和吸收能显著降低(P<0.05)，呼吸能无显著差异(P>0.05)，排泄能显著增加(P<0.05)，生长余力极显著降低(P<0.01)；中期(30 d)海水酸化胁迫下，摄食能降低(P<0.05)，吸收能、呼吸能、排泄能、生长余力显著升高(P<0.05)。氧氮比的结果显示，在海水酸化胁迫下，氧氮比的波动范围为14.28~20.46，贝类体内的供能物质由脂肪和碳水化合物逐渐向蛋白质过渡。研究结果为揭示紫贻贝应对海水酸化胁迫的生理响应提供了基础数据。

英文摘要:

      The effect of seawater acidification on the energy budget of the mussel Mytilus galloprovincialis was studied using a combined in situ mesocosm and flow-through chambers approach in Sanggou Bay from May to June, 2016. The experimental groups of mussels were acclimated to different experimental pH values obtained by elevating seawater CO2 concentrations. Clearance rates, absorption efficiency, respiration rates, ammonia excretion rates, and O/N ratios of M. galloprovincialis were measured after 10 and 30 days of treatment. The results showed that the clearance rates, O/N ratios, and absorption efficiency of M. galloprovincialis were reduced significantly after 10 days of exposure to acidified seawater (pH 7.7) (P<0.05), whereas the rates of ammonia excretion were increased significantly (P<0.01). The respiration rates in acidified and ambient seawater did not show significant difference (P>0.05). However, after 30 days of exposure to acidified seawater, significantly increased absorption efficiency, respiration rates, and ammonia excretion rates (P<0.05), and significantly reduced clearance rates and O/N ratios were observed (P<0.05). Energy budget analysis showed that a 10-day exposure to acidified seawater resulted in significantly reduced ingestion energy, absorbed energy, and scope for growth (P<0.05), but a significant increase in excreted energy (P<0.05), whereas a 30-day exposure to acidified seawater resulted in significant reduction in ingestion energy (P<0.05), but a significant increment in absorbed energy, respiration energy, excreted energy, and scope for growth (P<0.05). The average values of O/N ratios ranged from 14.28 to 20.46 in all the experiments, suggesting that the energy source changed gradually from fats and carbohydrates to proteins under low pH conditions. These data provide theoretical insights into the possible mechanisms underlying the impact of seawater acidification on the physiological responses of mussels.