卡罗藻有毒株与无毒株对菲律宾蛤仔的生长、存活及生理生化的影响

Effects on the survival, growth and physio-biochemical activity of Ruditapes philippinarum by toxic and non-toxic Karlodinium species

剧毒卡罗藻对双壳类生理生化过程的影响尚待研究解明.本文以菲律宾蛤仔为对象,比较研究了细胞大小形态一致的剧毒卡罗藻和无毒周氏卡罗藻对菲律宾蛤仔的生长、存活、摄食生理以及糖原含量的影响.结果显示,2种卡罗藻喂养下,菲律宾蛤仔稚贝均有生长,但有毒组的生长指标和存活率均显著低于无毒组.其滤水率和摄食率与藻密度呈近似幂函数相关,15×10~5cells·L为拐点藻密度;小于或等于此藻密度时,2组的摄食率和滤水率随密度增加而增加,且无显著差异;大于此密度时,有毒藻组滤水率和摄食率均显著低于无毒藻组.成贝较稚贝能耐受更高有毒藻密度.摄食2种卡罗藻后,菲律宾蛤仔各组织均快速累积糖原,外套膜糖原含量最高,变化最为显著.但糖原累积量与藻密度有关,低藻密度组中,有毒藻组的糖原含量显著低于无毒藻组.研究结果表明,剧毒卡罗藻可以通过降低贝类摄食能力、干扰生化代谢等非急性致死过程来影响贝类的生长及存活.

How the dinoflagellate Karlodinum veneficum affect the growth and physio-biochemical metabolism of bivalves requires further research. In this study, two morphologically identical but of different toxicity species,namely the toxic K. veneficum, and the non-toxic K. zhouanum, were applied in the detection of their effects on the survival, growth, grazing activity and glycogen content of manila clam(Ruditapes philippinarum) juveniles or adults. The results show that both species support the clam for growth. But the growth and survival rates were significantly lower in the toxic algal group than those in the nontoxic one. Both filtration and ingestion rates changed along with the algal cell densities, resembling power function relationship in both algal groups. The algal density at the inflection point was 15×10~5 cells·L. In algal groups of lower or equal to this density, the filtration or ingestion rates increased along with the increased algal density. There was no significant difference in two algal groups. When algal cell densities were equal to(or higher than) 15×105 cells·L, the filtration and ingestion rates were significantly lower in toxic algal groups than those in non-toxic ones. The adult clam showed higher algal density tolerance than the juveniles. The glycogen contents in the starving adult clam increased rapidly after feeding both Karlodinium species of different densities. The changes were the most significant in mantle where the glycogen contents were the highest. The increase of glycogen content was related to the algal species and density. In low algal density group, the glycogen content in toxic group was significantly lower than that in non-toxic algal groups. This study showed that, toxic Karlodinium species may affect the growth and survival of the clam through certain non-acute processeses, such as by impacting the normal grazing process and interfering the biochemical metabolisms.