海鞘幼体附着机制的研究

Marine fouling organisms such as ascidian will cause serious damage to warships, boats, oil drilling platforms on the sea, the cooling tubes of coastal power plants, aquiculture facilities and so on. Although tributyltin paint used nowadays is good for antifouling, marine environment is polluted severely by it. So IMO has progressively restricted the use of tributylin as an active ingredient in antifouling paints. Therefore, the study of nontoxic marine antifouling paint is in imminence..The contents of this study include: the morphology and behavior of embryonic and larval development in Styela canopus, determination of competence of larval metamorphosis in S. canopus, ionic control of larval settlement and metamorphosis, chemical cues inducing conspecific aggregation in S. canopus, the effects of neurotransmitters, their analogs, salinity, microfilms, extracts of marine fouling organisms on the settlement and metamorphosis of S. canopus larvae. .It was 9.5~11 hrs for larvae of S. canopus to hatch after fertilization. S. canopus larvae developed competence to initiate settlement and metamorphosis at least 3 hrs after hatching. But if there was no induction, larvae could keep a stage of plankton for at least 3~4 days. High concentrations of potassium ion and low concentrations of magnesium ion both could induce remarkably the settlement and metamorphosis of S. canopus larvae. In natural seawater, the optimum concentration of K+ for inducement was +40mM. TEA (Tetraethylammonium chloride), a potassium channel blocker, failed to inhibit the inductive effect of K+-elevated seawater, indicating that the potassium channels inducing the settlement and metamorphosis of S.canopus larvae is insensitive to external TEA. 1×10-6M L－DOPA could induce S.canopus larvae to settle and metamorphose. However, adrenaline and noradrenaline didn't show any significant inductive effects. On the other hand, acetylcholine inhibited S.canopus larvae to settle and metamorphose. R-aminobutyric (GABA) and picrotoxin also showed notable inhibitory effects on the settlement and metamorphosis of S.canopus larvae. But neither inductive nor inhibitory effects of L-Thyroxine had been found to show in a remarkable way. We isolated four strains of monobacteria which could induce the settlement of S.canopus larvae. But H-9 (Vibro), H-4 (Vibro) and H-7 (Lactobacillus) showed inhibitory effects on the metamorphosis of S.canopus larvae. The bacterial film mixing 9 strains of bacteria could facilitate markedly S.canopus larvae to settle and metamorphose. The water-soluble extracts of the tunic of S.canopus could induce the settlement and metamorphosis of S.canopus larvae in a significant way. Styela Canopus larvae were induced to settle and metamorphose at densities of more than 10 larvae per mL, suggesting that larvae contain inductive chemical factors. We also found that the liposolube extracts of two sponge species can inhibit S.canopus larvae to settle and metamorphose. This study also advanced the complex model of the mechanism of larval settlement and metamorphosis in S.canopus. Ascidian is one of the common biofouling organisms in our country's coast. Studying the mechanism of its settlement and metamorphosis is very important for its prevention and elimination and will provide scientific basis for the invention of non-toxic antifouling coating..

采用室内实验和海区挂板试验相结合的方法，研究海鞘幼体附着行为生态、污损生物群落中其它生物和系列化因子对海鞘幼体附着和变态的抑制或诱导作用以及外加人工药物的诱导或抑制作用，综合探讨并阐明海鞘幼体附着机制问题。研究成果可为环保型海洋防污新技术开发提供重要的理论依据，也进一步充实新兴的海洋化学生态学和幼体生态学理论资料。