Physiology and ecology of ciguatera causative dinoflagellates

对日本冲绳赤岛岛赤岛岛底栖甲藻的分布进行了研究。包括1个新种在内的原甲藻在种群密度中所占比例较高。毒冈比亚是CTX和MTX的主要产生者，密度较低，但其最大细胞密度是冲绳岛和石垣岛的1000倍。新种为微细原甲藻，但扫描电子显微镜观察证实了瓣膜形状和瓣膜表面凹陷的差异。制作了一种新型荧光仪来监测底栖甲藻的生长。在积分球中放置培养管，扩散激发光和体内荧光。因此，无需搅拌即可监测到荧光。对底栖硅藻和甲藻的培养进行了积分球荧光仪(ISF)的性能测试，体内荧光与提取的叶绿素含量具有良好的相关性，考察了光、温度和大型藻类渗出物对底栖原甲藻生长的影响。它们的最适生长量分别为1.1-1.4×10~(-1)×10~(-1)和25.5~30.7ﾟ℃。褐藻和褐藻表面释放的渗出物能促进P.Lima、P.sp.和P.emarginatum，而P.acavum.相反，在田间观察到原甲藻大量附着的斑纹藻分泌物对4种植物的生长有一定的干扰作用。从这些结果来看，它们附着在宿主上的好处被认为是除了提供促进生长的物质外，还可以遮蔽高光照。

Distribution of benthic dinoflagellates including ciguatera causative organisms were examined in Akajima Island, Kerama Islands, Okinawa, Japan. Prorocentrum species including a new species occupied high percentage of density compared with others. Gambierdiscus toxicus known as a main producer of CTX and MTX was rater low in the density, but its maximum cell density was a thousand times higher than that examined at Okinawa Island and Ishigaki Island. The new species recembles Prorocentrum emarginatum but the difference in the valval shape and depression on the valve surface were confirmed by scanning electron microscopic observations.A new type of fluorometer was made to monitor the growth of benthic dinoflagellates. A culture tube is placed in the integrating sphere which diffuse both excitation light and in vivo fluorescence. Thus the fluorescence is monitored without agitation. The performance of integrating-sphere-fluorometer (ISF) was tested for cultures of a benthic diatom and dinoflagellates, and good correlations were obtained between in vivo fluorescence and extracted chlorophyll amounts.Effects of light, temperature and exudate of macroalgae on growth of benthic Prorocentrum species were examined. Their optimum growth were observed between 1.1-1.4x10^<16>quanta cm^<-2> sec^<-1> and 25.5-30.7 ﾟC, respectively. The exudate released from the surface of Zonaria stipitata and Distromium decumbens (Phaeophyceae) promoted the growth of P. lima, P. sp. and P. emarginatum but P. concavum. On the contrary, the exudate of Turbinaria ornata, on which abundant adhesion of Prorocentrum was observed in the field, rather disturbed the growth of four species. From these results, benefits of their adhesion to the host macroalge were thought as a shading from high irradiance besides the supply of growth promoting substances.