Changes in intracellular polyamine concentration during growth of Heterosigma akashiwo (Raphidophyceae)

ABSTRACT:   Of the free, conjugated and bound forms of polyamines, the free form of spermidine was the most abundant polyamine in Heterosigma akashiwo throughout the growth period except for the lag phase. Free spermidine content increased remarkably during the exponential growth phase and increased as the growth rate increased. The maximum growth yield of H. akashiwo was reduced by the addition of methylglyoxal bis-guanylhydrazone (MGBG) and the reduced growth yield could be counteracted by the addition of spermidine to the medium. It is concluded that spermidine plays a significant role in the growth of H. akashiwo . These results are similar to those obtained in Chattonella antiqua that belongs to same taxonomic Class as H. akashiwo .     

Effects of temperature and light intensity on the growth and toxicity of Heterosigma akashiwo (Raphidophyceae)

The effects of temperature and light intensity on the growth and toxicity of Heterosigma akashiwo (Hada) were studied in the laboratory. The growth and toxicity of this organism were found to be greatly influenced by temperature and light intensity. The best growth was found at 25 °C where the toxicity was very low. On the other hand, cells were found to be most toxic at 20 °C (0.087 ± 0.005 FU), although the growth was much less than at 25 °C. The lowest toxicity was observed at 30 °C with a toxicity of 0.011 ± 0.005 FU. The toxicity of this species also differed markedly at different light intensities. It gave the maximum toxicity at 200 μE m^?2 s^?1, but poor growth. The best growth occurred at 100 μE m^?2 s^?1, but with a marked toxicity drop. In toxin composition studies, the amounts of most of the toxic fractions were lower at 25 °C and 100 μE m^?2 s^?1 where the growth was most conspicuous.     

日本鹿儿岛湾真鲷的资源评估和增殖策略

通过世代分析对1990年至2002年鹿儿岛湾真鲷（Pagrus major）自然种群和放流种群的种群大小进行了评估,评估模型考虑了渔业资源管理和增殖放流措施。结果表明放流种群的规模有所减少,而自然种群的规模维持不变。真鲷自然种群的捕获量日趋减少,而放流种群的捕获量已超过50吨。研究结果表明增殖700000—800000尾真鲷种苗与其50吨的捕捞量相协调。在各种捕获量和放流量情况下,采用种群动力学模型预测了2017年真鲷的捕获量,其结果表明提高放流真鲷的数量能增加其捕获量。     

海州湾海域的赤潮生物

利用2003—2008年海州湾海域浮游植物的调查资料,对海州湾海域常见的赤潮生物进行描述、归纳及总结,为赤潮的常规监测和应急监测提供背景资料。结果表明,在海州湾海域共监测到121种赤潮生物,其中重要的赤潮生物有:中肋骨条藻、夜光藻、多纹膝沟藻、短角弯角藻、赤潮异弯藻、链状裸甲藻、海链藻属,这7种(属)赤潮生物都曾经在该海域引发过赤潮。此外,中华盒形藻、海洋原甲藻、梭角藻、三角角藻、圆筛藻属、角毛藻属等赤潮生物在海州湾海域常年分布,也具有引发赤潮的可能。     

Molecular identification of red tide-causing microalga Heterosigma akashiwo strains based on their chloroplast DNA sequences

ABSTRACT:   In order to establish genetic signatures for intraspecific identification, parts of the genes rbcL , rbcS and psbA and their intergenic spacer (IGS) regions were amplified by polymerase chain reaction (PCR) from the chloroplast genomes of Heterosigma akashiwo strains isolated from Japan. A transfer RNA-Leu gene trnL and a hypothetical gene cfxQ , which is related to ribulose bisphosphate carboxylase/oxygenase expression, were found in the upstream region of the rbcL gene and in the rbcS-psbA IGS region, respectively. All the gene-coding regions and the IGS regions between rbcL and rbcS showed the same sequences among the strains tested. In contrast, the rbcL upstream regions and the rbcS-cfxQ IGS regions showed some differences such as nucleotide substitutions, duplications and inversions between NIES-5 and the other strains. Based on these sequence data, five genetic signatures were established and their simple and rapid detection by means of strain-specific PCR primers and PCR-restriction fragment length polymorphism techniques was examined. The results suggested the usefulness of these genetic signatures and techniques for the discrimination of H. akashiwo populations.     

赤潮异弯藻对鳀鱼早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对鳀鱼(Engraulis ja ponicus)早期发育阶段的影响进行了研究。并就鳃鱼早期发育过程中对赤潮异弯藻的敏感性时期作了探讨。实验结果表明,原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻细胞内容物对鳃鱼早期发育各阶段的毒性最大,其次是藻细胞碎片和藻液,去藻过滤液的毒性最小。暴露在高浓度90000c／ml藻细胞内容物中,96h后仔鱼的存活率为4％;而在同浓度的去藻过滤液中,96h后仔鱼的存活率为75％。藻细胞内容物和藻细胞碎片对鳃鱼仔鱼96hI。C∞分别为2818、6760c／mL．     

营养因子对赤潮异弯藻生长的影响

以赤潮异弯藻为材料,采用正交试验方法,研究了氮、磷、微量元素混合液和维生素混合液对赤潮异弯藻生长的影响。试验结果表明,在对数期和稳定期,4种营养因子中对赤潮异弯藻生长影响的顺序为磷>维生素>氮≥微量元素;在衰亡期,营养因子中对赤潮异弯藻生长影响的顺序为氮>磷>维生素>微量元素。在对数期,氮、磷、微量元素和维生素等营养因子的最适浓度分别为880、18、10.55、0.32μmol/L;在稳定期和衰亡期,最适浓度分别为2640、108、21.1、0.96μmol/L。各营养因子在不同时期均对赤潮异弯藻的增殖具有显著影响(P<0.01)。     

赤潮异弯藻对牙鲆早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对牙鲆(Paralichthys olivaceus)早期发育阶段的影响及敏感性时期作了探讨。实验结果表明，原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻液对牙鲆早期发育各阶段的毒性最大，其次是藻细胞碎片和藻细胞内容物，去藻过滤液的毒性最小。暴露在高浓度80000cells／ml藻液中，96h后仔鱼的存活率为47．6％；而在同浓度的去藻过滤液中，96h后仔鱼的存活率为90％。藻液对牙鲆仔鱼96h LC50为35042cells／ml。     

同安湾赤潮监测站位优化设置

根据同安湾赤潮监测资料,对监测站位进行二次背包模型优化。将现有4个监测点优化为3个最佳监测点,研究表明,优化后的站位所表征的赤潮监测信息量,与原监测信息量等效,可作为今后的常规监测站位。二次背包模型对海洋环境监测站位优化布设非常适用,模型具有简易性和实效性。本文应用MATLAB和LINGO数学软件,详细介绍二次背包模型的求解过程。程序简单、方便使用。     

赤潮异弯藻对孔石莼生长及其某些生理特性的影响

通过实验生态学和生物化学的方法,研究了赤潮异弯藻[Heterosigma akashiwo(Hada)Hada]对孔石莼(Ulva pertusa Kjellman)生长及其叶绿素a(Chl-a)含量、丙二醛(MDA)含量、总抗氧化能力(T-AOC)、过氧化氢酶(CAT)活力、超氧化物歧化酶(SOD)活力和谷胱甘肽过氧化酶(GPX)活力的影响。结果表明:孔石莼的克生作用会明显抑制赤潮异弯藻的生长,同时赤潮异弯藻也会抑制孔石莼的生长,且孔石莼生理生化特性对其有明显的响应。赤潮异弯藻会使孔石莼CAT活力和MDA含量呈现升高的趋势;GPX活力呈现下降的趋势;T-AOC和T-SOD活力呈现先下降后升高趋势;Chl-a含量并无明显变化。推测赤潮异弯藻克生作用诱导孔石莼产生活性氧自由基,是藻体受损伤的主要原因。     

Phylogenetic analysis of noxious red tide flagellates Chattonella antiqua, C. marina, C. ovata, and C. verruculosa (Raphidophyceae) based on the rRNA gene family

ABSTRACT:   Four species of Chattonella , which are well known to form red tides that are lethal to fish, were subjected to phylogenetic analysis on the basis of the ribosomal RNA genes (rDNA), 5.8S rDNA, 18S rDNA, 28S rDNA, and the flanking internal transcribed spacers 1 and 2 (ITS1 and ITS2). The 18S rDNA sequences of C. antiqua , C. marina , and C. ovata isolated from different regions in Japan were compared. They were found to be identical with each other in a sequence 1818 bp long. The sequences of the D1/D2 region in the 28S rDNA, 5.8S rDNA, and ITS region that are known to be more variable regions were also found to be identical. These homogeneities of the rRNA gene family revealed the extremely close relatedness of C. antiqua , C. marina , and C. ovata . The sequences of C. verruculosa were different from those of these three species , resulting in an 89.2% homology in the 18S rDNA sequences, 70.4% homology in the D1/D2 region in the 28S rDNA sequences, and an 81.5% homology in 5.8S rDNA sequences and the ITS regions. Chattonella verruculosa was grouped within a single cluster composed of Dictyochophyceae rather than the other species of Raphidophyceae.     

Physiological investigations of a neurotoxin-producing phytoflagellate, Chattonella marina (Raphidophyceae)

The effects of temperature, salinity, light intensity and pH on the growth and morphology of Chattonella marina (Subrahmanyan) Hara & Chihara were examined. Optimal growth was observed at temperatures of 20-25°C, salinities of 20-30%o, light intensities of 60-140 μE m^?2 s^_1 and pH 7.5-8.5. Growth did not occur at temperatures below 15°C or above 30°C, and at salinities below 10%o. The morphology (shape) of the cells was strongly affected by temperature. At 20°C and 25°C, the population occurred mostly in a spindle-like form, whereas at 10°C, 90% of the cells became spherical within 10 days of inoculation and stationary phase cultures consisted entirely of spherical cells. Morphology was also markedly affected at 30°C. The number of spindle-like cells was highest at 20-30%o and was less at lower salinities. Light intensity and pH did not influence morphology markedly under the range of light intensities (20-180 μE m ^?2 s-^?1) and pH (6.5-8.5) tested.     

胶州湾浮动弯角藻赤潮生消动态过程及其成因分析

分析了1999年6月8日-15日胶州湾东北养殖消耗域浮动弯角藻赤潮生消动态过程中各环境因子的变化及赤潮成因，结果表明，该海域无机营养盐含量较高，为赤潮的发生提供了必需的营养物质；赤潮发生前天气闷热无雨，有利于浮动弯角藻的快速生长繁殖；赤潮形成至发展期该海域盛行南风，浮动弯角藻的物理性聚集对赤潮迅速形成有重要影响；赤潮维持阶段天气稳定，赤潮持续时间较长；最终无机磷、活性硅酸盐的耗尽使赤潮逐步走向消亡。     

Effects of temperature, salinity and irradiance on the growth of the toxic dinoflagellate Gymnodinium catenatum (Dinophyceae) isolated from Hiroshima Bay, Japan

ABSTRACT: Temperature and salinity ranges in which Gymnodinium catenatum (Hiroshima Bay strain) showed specific growth rates higher than 0.2/day were approximately 20–30°C and 20–32. The specific growth rate (μ), expressed as a polynomial equation as functions of temperature ( T ; °C) and salinity ( S ) were μ = (−6.84 × 10⁻⁴ T ² + 0.0354 T – 0.213) × (−1.03 × 10⁻³ S ² + 0.0579 S – 0.548)/0.31; the maximum growth rate (0.31/day) was obtained at 25°C and 30. From a comparison with field data recording temperature, salinity and light intensity, this species may be expected to bloom from summer to autumn in Hiroshima Bay.     

Growth Characteristics of a Neurotoxin-Producing Chloromonad Fibrocapsa japonica (Raphidophyceae)

The effects of temperature, salinity, irradiance and pH on the growth of Fibrocapsa japonica (Raphidophyceae) were examined to determine how environmental factors affect the distribution of this species. Optimal growth was observed at temperatures of 15–25 C, salinities of 25–35 parts per thousand (ppt), irradiances of 60–140 μmol quanta/m² per s and pH between 7.5–8.5. Growth did not occur at temperatures below 10 C or above 30 C nor at salinities below 15 ppt. Fibrocapsa japonica grew when subjected to irradiances of 20–180 μmol quanta/m² per s, and could tolerate a pH range of 6.5–8.5.     

Neurotoxin Production by a Chloromonad Fibrocapsa japonica (Raphidophyceae)

The ichthyotoxicity and toxin composition of a red-tide producing chloromonad Fibrocapsa japonica (Toriumi and Takano) were examined. The flagellate showed the highest toxicity in mid-logarithmic phase and the lowest in the stationary phase with increased number of spherical-shaped cells. Five neurotoxic components, FjTx-I, FjTx-II, FjTx-IIIa, FjTx-IIIb and FjTx-IV, which corresponded to brevetoxin components, PbTx-1, PbTx-2, PbTx-9, PbTx-3 and oxidized PbTx-2 were tentatively identified from analysis of F. japonica toxins on TLC and HPLC. The quantity of each component fluctuated with the age and growth stage of the culture. Among the five toxic components the yield of FjTx-II per cell was highest in both logarithmic and stationary phases.     

Comparison of environmental conditions in two representative oyster farming areas: Hiroshima Bay,western Japan and Oginoham a Bay (a branch of Ishinomaki Bay), northern Japan

ABSTRACT:   Sea water environmental conditions over annual cycles were investigated and compared between two oyster farming areas, western Hiroshima Bay and Oginohama Bay (a branch of Ishinomaki Bay) in Miyagi Prefecture, to appropriately manage oyster culture or more efficiently utilize farming areas. The environmental parameters of temperature, salinity, nutrient concentrations (NO₂–N, NO₃–N, NH₄–N, PO₄–P, and SiO₂–Si) and size-fractionated chlorophyll- a (<0.2, 2–20, >20µm), and abundances of microzooplankton were measured in each bay at the surface, and 2 and 5 m depth layers. Differences in the annual mean values and results with monthly paired Student's t -tests showed that salinity was lower, and temperature, nutrient (especially PO₄–P) and chlorophyll- a concentrations, and abundance of microzooplankton, were higher in Hiroshima Bay than in Oginohama Bay. Differences in environmental conditions between inshore and offshore areas of each bay suggest that inflows of river water in western Hiroshima Bay and sea water from offshore had the most significant effects on the environmental conditions. It is concluded that such oceanographic and biological differences strongly affect the oyster farming system, especially regarding the optimum usage of offshore areas in Summer under clean, cold and stable seawater conditions, rather than food quantity in Hiroshima Bay, and under more abundant food conditions in Oginohama Bay.     

赤潮预报和防治方法

前言赤潮一般定义为:在一定条件下,海水中某些浮游植物、原生动物或细菌在一段时间内突发性增殖或高度聚集引发生态异常并造成危害的现象.20世纪50年代以来,随着各国工农产业和水产养殖业迅猛发展,赤潮灾害频频发生,针对此现象国际上许多组织陆续地将赤潮列入研究计划,如ICES(国际海洋勘探理事会)/IOC(政府间海洋学委员会)等都成立了相应赤潮研究组.