Growth competition between toxic dinoflagellate, Alexandrium, and diatom.

塔玛拉藻与海链藻、Cheatoceros、海星藻等硅藻的共生培养显示出相互抑制生长的作用。抑制程度取决于混合菌种的细胞密度比例。塔玛依和中肋骨条藻在双藻培养过程中表现出不同的生长模式。在这种情况下，即使在相对细胞密度显著不同的情况下，两个物种也不会对彼此表现出显著的生长抑制。这些结果与大船渡湾观察到的物种演替规律很好地吻合，表明这些生长竞争是控制浮游植物群落组成的重要因素之一。在双藻养殖过程中，监测了环境因子如pH、光照强度和营养物质浓度。然而，这些因子的变化与生长竞争之间没有明显的关系，表明生长抑制是由其他m-…引起的更多的机械性。另一方面，塔玛沙门氏菌的培养基能明显抑制海链藻的生长，表明塔玛沙门藻细胞分泌的某些物质(S)参与了上述生物藻类培养中观察到的海链藻的消亡。塔玛沙门氏菌和Cheatocers的培养基对塔玛沙门氏菌的生长也有抑制作用，而对骨架线虫的影响不明显。这些结果表明，化感物质在塔玛艾美耳藻和硅藻之间的生长竞争中起着重要作用。在自然环境中，硅藻的生物量远超塔玛藻类。因此，硅藻对塔玛沙门氏菌的生长抑制似乎对控制物种组成更为关键。塔玛沙门氏菌对海链藻的化感物质为脂溶性物质。海链藻对塔玛沙鼠的化感作用物质也是脂溶物质。层析行为表明，该物质是一种碳氢化合物。较少

Bialgal cultures between A.tamarense and diatom such as Thalassiosira, Cheatoceros, or Asterionella showed the growth inhibition to each other. Adegree of inhibition depended upon proportion of cell density of the species mixed. On the other hand, different growth pattern was observed in the bialgal culture between A.tamarense and Skeletonema costatum. In this case, both species did not show significant growth inhibition to each other even when the relative cell density is significantly different. These results well coincided with species succession pattern observed in Ofunato Bay, indicating that these growth competition is one of the important factors which control a composition of phytoplankton community.Environmental factors such as pH,light intensity and nutrient concentration were monitored during the process of bialgal culture. However, no clear relationship was observed between change of these factor and growth competition, indicating that growth inhibition is caused by other m … More echanism. On the other hand, the cultured medium of A.tamarense clearly inhibit the growth of Thalassiosira sp., showing that some substance (s) secreted from A.tamarense cells involves in extinction of Thalassiosira observed in bialgal culture described above. Growth of A.tamarense was also suppressed by the cultured medium of Thalassiosira and Cheatocers, whereas no effect was observed in the case of Skeletonema. These results suggest that allelochemic substance plays anpimportant role in growth competition between A.tamarense and diatoms. In natural environment, biomass of diatoms is overwhelming to compare that of A.tamarense. Therefore, growth inhibition by diatoms to A.tamarense seems to be more crucial for controlling a species composition. Allelochemic substance of A.tamarense to Thalassiosira was characterized as lipid soluble substance. Substance of Thalassiosira showing allelopathy effect on A.tamarnese was also lipid soluble one. Chromatographic behavior revealed that the substance is a kind of hydrocarbon. Less