盐度骤降对近江牡蛎和长牡蛎能量收支的影响

Effects of acute salinity changes on energy budgets of oysters Crassostrea ariakensis and Crassostrea gigas

中文关键词: 盐度  长牡蛎  近江牡蛎  能量收支

英文关键词: Salinity  Crassostrea gigas  Crassostrea ariakensis  Energy budget

中文摘要:

      采用实验生态学方法，研究了盐度骤降(盐度分别为10、20，自然海水为对照组)对近江牡蛎(Crassostrea ariakensis)和长牡蛎(Crassostrea gigas)生理代谢的影响。结果显示，盐度骤降对长牡蛎和近江牡蛎的耗氧率(OR)、排氨率(NR)、排粪率(FER)均有显著影响(P<0.05)，且2种牡蛎对盐度骤降的响应存在差异。长牡蛎的耗氧率、排氨率、摄食率(IR)和排粪率均在自然海水中最高，低盐对长牡蛎产生不同程度的胁迫。而近江牡蛎在盐度为20时的上述指标显著高于其他盐度处理组。通过测定不同规格牡蛎的代谢率，建立2种牡蛎在不同盐度下的代谢率与规格(湿重)的回归方程，该方程符合幂指数：Y=aWb。通过归一化处理，比较湿重在20 g时，2种牡蛎的能量分配差异。盐度为20时，近江牡蛎的呼吸代谢较强(呼吸能占16.1%)，而长牡蛎在自然海水中呼吸代谢较强(呼吸能占7.8%)，2种牡蛎的呼吸代谢均在盐度为10时较低，其中，长牡蛎呼吸能仅占0.7%。研究表明，盐度骤降对长牡蛎的影响大于近江牡蛎，小幅度的盐度骤降对近江牡蛎的能量代谢有一定的促进作用。本研究从能量代谢角度，探讨了近江牡蛎和长牡蛎对盐度骤变的响应，可为牡蛎礁修复工作和养殖生产过程中的品种选择提供参考。

英文摘要:

      The restoration of oyster reefs is a hot issue and has being attracting the attention of researchers worldwide. Crassostrea gigas and C. ariakensis are two important species that build up oyster reefs; however, the population dynamics of these two species in low-salinity estuaries are not the same. We used experimental ecology methods to study the effects of acute lowered salinity (10 and 20, with natural seawater about 29 as a control) on the variations in the physiological metabolism of C. gigas and C. ariakensis. The results showed that acute lowered-salinity incubation significantly affected the oxygen consumption rate, ammonia excretion rate, and feces production rate of these two oysters (P < 0.05), but the responses of these two species were also different. The highest oxygen consumption rate, ammonia excretion rate, feeding rate and feces production rate of C. gigas were found in the control group, which indicated that a decrease in salinity impacted the metabolism of this species. However, C. ariakensis showed better metabolic parameters at salinity 20 than that in the other two groups. To normalize the metabolic rate of oysters with a broad range of wet weights, a regression equation for the metabolic rate to wet weight was established: Y=aWb. The wet weight (20 g) was used for the comparison after normalization. At salinity 20, the respiration rate of C. ariakensis was strong, and the respiration energy accounted for 16.1% of the total energy consumption, while C. gigas showed a stronger oxygen consumption rate in natural seawater (respiratory energy accounted for 7.8% of the total energy consumption), and a lower oxygen consumption rate at salinity 10 (respiratory energy accounted for 0.7% of the total energy consumption). Our results indicated that the acute lowered-salinity incubation had a more significant influence on C. gigas than C. ariakensis, and a low-level reduction in salinity can even promote the energy metabolism of C. ariakensis. From the perspective of energy metabolism, this study explored the response of C. gigas and C. ariakensis to acute reductions in salinities, and provided references for oyster reef restoration, selective breeding, and aquaculture.