光照对不同规格番红砗磲(Tridacna crocea)氧、氨氮及活性磷酸盐代谢的影响

Effects of Illumination and Size on Metabolism of Oxygen Consumption, Ammonia and Active Phosphate Excretion in Giant Clam Tridacna crocea

在水温24–26℃下,采用室内实验生态学方法,研究了5000 lx光照强度和黑暗对壳长为(63.53±1.22)mm(S组)、(75.87±1.50)mm(M组)和(92.75±3.02)mm(L组)番红砗磲(Tridacna crocea)氧、氨氮及活性磷酸盐代谢的影响。结果显示,光照条件下,番红砗磲释放氧气,吸收氨氮和活性磷酸盐。黑暗条件下,番红砗磲代谢状况与其他双壳贝类类似。番红砗磲个体代谢率与规格密切相关:光照条件下个体越大,产氧率、对氨氮和活性磷酸盐吸收率越高;黑暗条件下,个体越大,耗氧率、对氨氮和活性磷酸盐释放率亦越高。光照条件下,番红砗磲软体部单位干重代谢率与其个体规格呈负相关,个体越大,单位干重的产氧率、氨氮和活性磷酸盐的吸收率越小。实验首次量化了不同光照条件下番红砗磲对氧、氨氮及活性磷酸盐的吸收和排泄状况,结果可为研究番红砗磲在珊瑚礁生态系统中的作用提供依据,对砗磲人工养殖也具有一定的参考。

The effects of illumination （5000 lx illumination and darkness） and size [shell length： （63.53±1.22） mm as ＂small＂ group, （75.87±1.50） mm as ＂medium＂, and （92.75±3.02） mm as ＂large＂] on the metabolism of dissolved oxygen, ammonia nitrogen and active phosphate in the giant clam Tridacna crocea were studied under laboratory conditions at 24-26 ℃. The results showed that under illumination, T. crocea released oxygen and absorbed ammonia nitrogen and active phosphate; the metabolism of T. crocea was similar to other bivalve mollusks in the dark. The metabolism rate of individual T. crocea was closely related to the size. Under illumination, the oxygen-production rate and the ammonia nitrogen/active phosphate absorption rate had a highly positive correlation with the size; in the dark, on the contrary, there was a negative correlation between the size and the oxygen production rate and the ammonia nitrogen/active phosphate absorption rate. Under illumination, the metabolic rate of symbiotic zooxanthellae （per gram of dry weight） of T. crocea was negatively correlated with the individual size. In this study, the metabolism of oxygen, ammonia nitrogen and active phosphate of T. crocea was quantitatively correlated with the size and light conditions for the first time. Our results provided basic information on the role of T. crocea in coral reef ecosystems and on the artificial breeding of giant clams.