高温、低盐对菲律宾蛤仔免疫能力的影响

为查明温度(21、30℃)和盐度(7、15、32)互作对菲律宾蛤仔Ruditapes philippinarum免疫能力的影响,对不同温度和盐度条件下试验0、3、6、12、24、48、72 h时,体质量为(14.8±0.731)g蛤仔的血细胞数、血淋巴吞噬能力和渗透压,以及血清中溶菌酶(LZM)、碱性磷酸酶(AKP)活性的变化进行了研究。结果表明:以各指标0 h水平为对照,常温常盐组(21℃,32)蛤仔各指标在0~72 h内虽有波动,但变化并不显著(P0.05);各试验组蛤仔血细胞数有不同的变化趋势,72 h时,常温低盐组(21℃,7)蛤仔恢复初始水平,而常温中盐组(21℃,15)、高温中盐组(30℃,15)和高温常盐组(30℃,32)蛤仔血细胞数最终仍未恢复,高温低盐组(30℃,7)蛤仔虽在24 h时恢复初始水平,但在48 h时全部死亡;高温常盐组蛤仔吞噬能力先升高后降低在72 h时仍低于初始水平(P0.05),2个中盐组和常温低盐组蛤仔吞噬活性最终恢复,而高温低盐组蛤仔吞噬活性在24 h时仍处于较高水平(P0.05);各试验组蛤仔LZM活性在72 h时均显著高于初始水平(P0.05);常温中盐组蛤仔AKP活性在3 h出现最大值,最终所有试验组AKP在72 h时恢复初始水平;2个中盐组和2个低盐组蛤仔渗透压均逐渐降低,而高温常盐组蛤仔渗透压逐渐升高,在72 h时均未恢复初始水平。研究表明,温度升高的同时降低盐度,将会对贝类免疫能力造成严重的影响,这可能是夏季滩涂贝类死亡率较高的一个重要原因。

Synergistic effects of high temperature and low salinity on immunity of Manila clam Ruditapes philippinarum

The changes in blood cell count, phagocytosis ability, osmotic pressure, and activities of lysozyme (LZM),and alkaline phosphatase(AKP) in serum were monitored in Manila clam Ruditapes philippinarum with body weight of (14. 8±0. 73)g exposed to temperatures(21 ℃, and 30 ℃) and a salinity of 7, 15, and 32 for 0, 3, 6, 12, 24, 48,and 72 h in order to investigate the synergistic effects of temperatures and salinity on the immuni-ty of Manila clam. The results showed that there were some fluctuations in blood parameters and activities of serum LZM and AKP in the experimental groups at water temperature of 21 ℃ and a salinity of 32 , without significant differences (P>0. 05) in 0-72 h compared with initial level in the control group. The blood cells counts were re-covered to the initial level in the clam in the 21℃ and low salinity of 7 group in 72 h, while the blood cells counts were not returned to the initial level in the clam in the 30 ℃, 32 ℃ and salinity 32 groups in 72 h. The clam in high temperature 30 ℃ and low salinity 7 group died in 48 h, although they had recovery blood cell count in 24 h. The clam in high temperature 30℃ and low salinity 7 showed elevated phagocytosis first and then decrease in hago-cytosisd, even lower than the initial level in 72 h(P<0. 05), while the clam in medium salinity 15 and 7 and 21℃groups had recovery phagocytic activities, with higher phagocytosis in high temperature 30 ℃ and low salinity 7 groups in 24 h ( P<0 . 05 ) . There were significantly higher LZM activities than the initial level in the clam among experimental groups in 72 h (P<0. 05), with the maximal AKP activity in 3 h and recovery initial levels in 72 h. The gradual decrease in osmotic pressure was observed in medium and low salinity groups, while the gradual in-crease in osmotic pressure in the high temperature 30 ℃ and salinity 32 group, without recovery initial level in 72 h. The findings indicate that the interaction of temperatures increase and salinity decrease will have a more serious effect on the immunity of shellfish, which may be involved in the high mortality of mudflat shellfish in summer.