氮和磷浓度对中肋骨条藻和锥状斯氏藻种间竞争的影响

采用室内单养和混养方法, 设置不同的氮、磷营养条件, 研究了氮、磷对中肋骨条藻(Skeletonema costatum)和锥状斯氏藻(Scrippsiella trochoidea)种间竞争的影响。结果表明: 混养时各氮和磷浓度下均呈现培养初期中肋骨条藻为优势种、培养后期锥状斯氏藻为优势种的变化趋势, 但随着氮、磷浓度的升高, 中肋骨条藻作为优势种的时间延长; 与单养时相比, 混养中两种微藻的最大密度受到不同程度的抑制, 表现出氮、磷浓度越高, 受抑制的程度越大的特征, 且与锥状斯氏藻相比, 中肋骨条藻的最大密度受到抑制的程度更大。混养时两种微藻均是在氮、磷浓度最高时, 抑制起始点出现时间最长, 随着氮、磷浓度的降低, 抑制起始点出现时间缩短; 各氮、磷浓度条件下, 锥状斯氏藻对中肋骨条藻的竞争抑制参数明显高于中肋骨条藻对锥状斯氏藻的竞争抑制参数, 当氮浓度为512 μmol·L^-1、磷浓度为2 μmol·L ^-1时, 竞争结果是锥状斯氏藻获胜; 其余氮、磷浓度条件下为两种微藻不稳定共存。     

不同起始密度对3种赤潮微藻种间竞争的影响

通过共培养的方法,研究了不同起始密度对赤潮异弯藻和中肋骨条藻、塔玛亚历山大藻和赤潮异弯藻、塔玛亚历山大藻和中肋骨条藻之间种间竞争的影响。结果表明1赤潮异弯藻对中肋骨条藻的生长有一定的抑制作用,随着初始接种时赤潮异弯藻细胞密度的提高,这种抑制作用愈加明显。2塔玛亚历山大藻和中肋骨条藻与塔玛亚历山大藻和赤潮异弯藻之间的种间竞争结果相类似,即起始密度比例为A∶S(H)=1∶4时,中肋骨条藻和赤潮异弯藻分别在竞争中占优势;当起始密度比例为A∶S(H)=1∶1和A∶S(H)=4∶1,塔玛亚历山大藻在竞争中占优势。     

海洋卡盾藻与中肋骨条藻和锥状斯氏藻种间竞争研究

研究了不同起始细胞密度与硅酸盐浓度对海洋卡盾藻(Cm)与中肋骨条藻(Sc)及锥状斯氏藻(St)之间种间竞争的影响,利用竞争抑制参数对相互间的竞争关系进行了分析,并引入体积竞争抑制系数的概念。结果表明:海洋卡盾藻的环境容量不受起始细胞密度(100—3600cells/mL)的影响,但随着起始接种密度的增加,达到最大细胞密度和进入稳定生长期的时间均提前。在硅缺乏的条件下,中肋骨条藻仍能保持一定生长,并能在与海洋卡盾藻之间的种间竞争中保持数量优势,但硅酸盐浓度的增加有利于其种间竞争。初始细胞密度和接种比例对3种赤潮藻类之间的种间竞争影响明显,总体来说海洋卡盾藻在竞争中处于劣势。当海洋卡盾藻细胞密度远远高于中肋骨条藻时(Cm:Sc=6:1),海洋卡盾藻才能在与中肋骨条藻的竞争中取胜;而在与海洋卡盾藻共培养条件下,锥状斯氏藻具有一定竞争优势,其对海洋卡盾藻的体积抑制系数(α’)是后者(β’)的27—100倍。但在所有处理中均没有绝对优胜者,竞争结果都会出现不稳定的平衡状态。       

3种海洋赤潮微藻蛋白质和核酸合成对UV-B辐射增强的响应

应用同位素标志法, 研究了赤潮异弯藻 (Heterosigmaakashiwo) 、亚历山大藻 (Alexandriumtamarense ) 和中肋骨条藻 (Skeletonemacostatum) 核酸和蛋白质合成对紫外线B波段 (UV_B, 2 80~ 32 0nm) 辐射增强的响应变化。结果表明 :1) 按照由高到低的顺序, 3种海洋赤潮微藻对UV_B辐射增强的敏感性依次是赤潮异弯藻、亚历山大藻和中肋骨条藻。 2 ) UV_B辐射增强抑制赤潮异弯藻的生长和脱氧核糖核酸 (DNA) 的合成, 而低剂量的UV_B辐射对中肋骨条藻和亚历山大藻的生长与DNA的合成表现出刺激作用, 高剂量则表现出抑制作用。 3) 随着UV_B辐射的增强, 3种海洋赤潮微藻核糖核酸 (RNA) 和蛋白质的合成速度下降, 其中赤潮异弯藻合成速度的下降幅度明显大于中肋骨条藻和亚历山大藻, 表明赤潮异弯藻RNA和蛋白质的合成对UV_B辐射增强的敏感性高于中肋骨条藻和亚历山大藻。     

UV-B辐射增强对三种赤潮微藻DNA的伤害效应

运用生态毒理学和生物化学方法研究了UV-B辐射增强对赤潮异弯藻、亚历山大藻和中肋骨条藻DNA的伤害作用.结果表明,3种赤潮微藻的生长状况对UV-B辐射增强的敏感性不同;对UV-B辐射增强的敏感性由高到低依次是赤潮异弯藻、亚历山大藻和中肋骨条藻.随着UV-B辐射剂量的增加,3种赤潮微藻的DNA损伤程度提高,而且赤潮异弯藻DNA的损伤程度明显高于亚历山大藻和中肋骨条藻,亚历山大藻DNA的伤害程度又远远高于中肋骨条藻.UV-B辐射处理解除后,损伤DNA可明显恢复.赤潮异湾藻和亚历山大藻恢复培养6d,损伤DNA可明显恢复(P＜0.05);而中肋骨条藻恢复培养3d,损伤DNA可明显恢复(P＜0.05),说明3种赤潮微藻的DNA损伤水平不适合作为指示UV-B辐射增强的生物学指标.     

一种有效去除赤潮生物的粘土复合体系

以粘土为主要成分,通过添加A、B两组分制备出能有效去除赤潮生物的粘土复合体系．设计了三因子三水平正交实验,考察了该体系对锥状斯克里普藻(Scrippsiella trochoidea)、强壮前沟藻(Amphi-dinium carterae)和赤潮异弯藻(Heterosigma akashiuo)的去除率,探讨了具有较高去除赤潮生物效果的复合体系对日本对虾(Penaeus japonicus)仔虾(体长1～1．5cm)的影响．结果表明,该体系对3种赤潮生物的去除能力为：锥状斯克里普藻>强壮前沟藻>赤潮异弯藻,各因子中粘土对赤潮生物去除效果的影响最大．日本对虾仔虾急性毒性实验结果表明,96h时对照组日本对虾仔虾死亡率高达80％,加入粘土和组分A、B的Ⅰ、Ⅱ及Ⅲ组死亡率均低于40％,适当浓度的组分A、B可以提高赤潮生物的去除率而对养殖生物无害,表明该复合体系具有较好的推广和应用前景．     

赤潮水体中胶体物质对赤潮异弯藻(Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)生长的影响

2004年2月9～10日在胶州湾发生的柔弱几内亚藻(Guinardia delicatula)赤潮期间分别在3个典型赤潮站位采集表层水样,利用过滤(0.7μm)和切向超滤(1000 Daltons)分离赤潮暴发水体中的胶体物质,分析了不同滤液及截留液的有机碳含量,并将赤潮异弯藻 (Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)在<1000 Daltons的超滤液及具有不同含量胶体物质(1000 Daltons～0.7μm)的截留液中进行培养.结果发现在发生柔弱几内亚藻赤潮期间水体中的溶解有机碳浓度会增加,特别是胶体有机碳浓度会成倍增长;在不同胶体含量海水中培养的赤潮异弯藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量的增加而显著增大,而中肋骨条藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量增加而显著降低,表明柔弱几内亚藻赤潮水体中的胶体物质对赤潮异弯藻的生长起促进作用,而对中肋骨条藻的生长起抑制作用.这说明柔弱几内亚藻在增殖过程中所产生的胶体物质具有他感作用,会影响其它微藻的生长,从而可能对柔弱几内亚藻赤潮的形成起重要作用.     

氮磷限制对锥状斯氏藻孢囊形成的作用

在实验室研究了锥状斯氏藻(Scrippsiellatrochoidea)在N、P单因子营养限制(N:500μg.L-1,P:74～0.74μg.L-1和P:74μg.L-1,N:500～5μg.L-1)条件下的生长和孢囊形成。结果显示N、P限制不利于锥状斯氏藻的快速生长,其中低P对细胞生长的限制作用更显著。其孢囊形成率在15～99%之间,中度N限制能促进孢囊的形成,形成率几乎可达100%。孢囊一般在对数生长期结束、细胞数量达到最大值时开始形成。但由于接种后营养盐浓度的急剧降低,营养极度限制组孢囊可在接种后第1d就开始形成。结果显示稳定生长期孢囊的大量形成大大降低了锥状斯氏藻营养细胞数量,能在一定程度上促进其赤潮的消亡。     

起始生物量比对3种海洋微藻种间竞争的影响

为深入了解饵料微藻与赤潮微藻间的种间竞争关系,通过微藻共培养的方法,研究了起始生物量比(1:4、1:1和4:1)对3种海洋微藻(塔玛亚历山大藻、蛋白核小球藻和湛江等鞭金藻)两两之间种间竞争的影响,并对其作用机制进行了探讨。结果表明:①3种海洋微藻表现出种间竞争的相互抑制效应;②在与塔玛亚历山大藻(简称A)的种间竞争中,蛋白核小球藻(简称C)和湛江等鞭金藻(简称I)均在竞争中占优势,蛋白核小球藻随自身起始生物量比的提高,其竞争优势越加明显,湛江等鞭金藻在A:I=1:1时竞争优势最为明显;在蛋白核小球藻和湛江等鞭金藻的种间竞争中,当C:I=1:4时,湛江等鞭金藻在竞争中占优势,C:I=1:1时,初期湛江等鞭金藻占竞争优势,随蛋白核小球藻的迅速生长,后期蛋白核小球藻占竞争优势,C:I=4:1时,蛋白核小球藻占绝对竞争优势;③由种间竞争抑制参数比较得出:3种微藻的种间竞争强弱依次为蛋白核小球藻>湛江等鞭金藻>塔玛亚历山大藻。蛋白核小球藻和湛江等鞭金藻在起始比例C:I=1:1时,可共培养利用,在海产经济动物育苗中可对其进行适时采收投喂;两种饵料藻对塔玛亚历山大藻具有明显的抑制作用,可为开发利用饵料藻进行赤潮生物防控提供一定的科学依据。     

甲藻孢囊在长江口海域表层沉积物中的分布

为了了解长江口海域赤潮爆发潜势,于2002年4月至5月用采泥器采集了位于122°～123．5°E、29°～32°N之间12个站位的表层沉积物,分析沉积物中甲藻孢囊的分布．共分析鉴定出孢囊类型29种,其中自养型11种,异养型18种．每个站位的孢囊种类在10～21之间,孢囊密度为11．7～587孢囊·g-1干泥之间．远岸海域孢囊种类较为丰富,密度也较高．在调查区域内,孢囊密度及种类自西向东、自北向南逐渐增加．亚历山大藻孢囊分布广泛,最高密度为40．4孢囊·g-1干泥,其他赤潮种类的孢囊如链状裸甲藻、多边舌甲藻、锥状斯氏藻、科夫多沟藻和无纹多沟藻等都在长江口海域有分布．     

UV-B辐射增强对海洋大型藻与微型藻种群生长关系的影响

选用孔石莼和青岛大扁藻为海洋大型藻和微型藻的代表,通过室内添加模拟试验研究了UV-B辐射增强对孔石莼(重量固定)与青岛大扁藻(密度不同)种群生长关系的影响。结果表明:(1)在单养情况下,4个UV-B辐射剂量都对孔石莼的生长产生抑制作用;对青岛大扁藻生长的影响却不同,低剂量(U-1)的UV-B辐射对青岛大扁藻的生长有促进作用,而高剂量的UV-B辐射则有显著的抑制作用;且因初始接种密度不同而各异。(2)在共养情况下,微藻对孔石莼的生长表现出一定的抑制作用,随着微藻初始接种密度的增加,其抑制作用亦增加;反之,在共培养的初始阶段(6 d内)孔石莼对微藻的生长也有抑制作用,但后期阶段(9 d后)表现出促进作用。(3)在共培养的同时附加UV-B辐射处理,随着初始接种密度的增加,青岛大扁藻对孔石莼生长的抑制作用更加明显;同时,与共养相比较,孔石莼对微藻生长的抑制作用亦趋于明显。     

Cryopreservation of Dunaliella salina and Platymonas helgolandica var. tsingtaoensis

Dunaliella salina (Dunal) Teod. and Platymonas helgolandica Kylin var. tsingtaoensis were cryopreserved in liquid nitrogen with a two-step cryopreservation method. With 5% and 20% dimethylsulphoxyde (DMSO) concentration respectively through 30 min equilibrium time, and under -40℃, 60 min and -30℃, 30 min respectively as prefreezing temperature and sustained time, and by using slow dilution method to remove DMSO from the sample at 0℃ and room temperature respectively after sample thawing, D. salina and P. helgolandica var. tsingtaoensis gained the highest survival rates that were 68.5% and 78.3% respectively.     

不同氮磷比率对青岛大扁藻、新月柱鞘藻和米氏凯伦藻生长影响及其生存策略研究

在不同氮磷比(N：P=1：1,4：1,16：1,80：1,160：1)条件下,对青岛大扁藻(Platymonas helgolandica var．tsingtaoensis)、新月柱鞘藻(Cylindrotheca closterium)和米氏凯伦藻(Karenia mikimotoi)3种浮游植物进行了培养,对其生长特性进行了比较研究．结果表明,不同氮磷比例对其生长有明显的影响,新月柱鞘藻在N：P=160：1时细胞比生长速率最快,而青岛大扁藻和米氏凯伦藻分别在4：1和80：1的条件下比生长速率最快．单位水体中细胞丰度的多少主要受细胞体积大小和自身比生长速率的影响．细胞内叶绿素a的合成浓度明显受氮的影响。高氮磷比例有利于叶绿素a的合成,细胞内可溶性蛋白质含量对不同氮磷比例有明显反应,且其含量多少与细胞大小和生长周期密切相关．3种浮游植物相对来说,新月柱鞘藻属于生长快速的r选择物种,而青岛大扁藻和米氏凯伦藻则为有较强适应环境能力的K选择物种．     

Studies on the transmission of WSSV (white spot syndrome virus) in juvenile Marsupenaeus japonicus via marine microalgae

We studied the possible role that marine microalgae may play during the outbreaks of WSS (white spot syndrome). In order to elucidate the possibility of marine microalgae carrying WSSV (white spot syndrome virus), six marine microalgae (Isochrysis galbana, Skeletonema costatum, Chlorella sp., Heterosigma akashiwo, Scrippsiella trochoidea, Dunaliella salina) were co-cultured with adult Marsupenaeus japonicus infected with WSSV and were assayed daily by nested-PCR to study whether they could carry WSSV. Further experiments were conducted to investigate whether the virus carried by microalgae could re-infect juvenile M. japonicus. Results showed that all of the experimental microalgae, except H. akashiwo could carry WSSV, and among them, Chlorella sp. and S. trochoidea had the strongest WSSV-carrying ability. Unlike other invertebrate carriers of WSSV, the WSSV detections in microalgae, which were positive after 1 and 3 days, were negative after 10days of incubation. WSSV detection results in juvenile M. japonicus showed that the juvenile shrimp were re-infected by co-cultured Chlorella sp., although the juvenile M. japonicus carried so small an amount of WSSV that it could only be detected by nested-PCR. The results of this experiment suggest that microalgae might be one possible horizontal transmission pathway for WSSV. Further research, however, is required to better understand the factors behind the different carrying abilities and virus-carrying mechanisms of different microalgae.     

ANTIALGAL ACTIVITY OF SOME SIMPLE PHENOLS1

The antialgal activity of a number of simple phenols was examined for their effect on the growth of 7 species of unicellular marine algae. The 3 knoiun algal phenols, 5-bromo-3,4-dihydroxybenzaldehyde; 2,3-dibromo-4,5-dihydroxybenzylalcohol, and 3,4-dihy-droxyphenylethylamine, were highly toxic as were other ortho dihydroxy compounds. Monohydroxy compounds were notably less toxic. Skeletonema costatum and Olisthodiscus sp. were the most sensitive organisms examined and Dunaliella tertiolecta was the most resistant. Possible ecological implications of these results are discussed.     

On the allelochemical potency of the marine dinoflagellate Alexandrium ostenfeldii against heterotrophic and autotrophic protists

Three strains of the marine dinoflagellate Alexandrium ostenfeldiiof different geographic origin were tested for their short-termdeleterious effects on a diversity of marine protists. All A.ostenfeldii strains were capable of eliciting an apparent allelochemicalresponse, but the various protistan target species were differentiallyaffected. Protists that were negatively affected by exposureto cells of A. ostenfeldii and associated extracellular metabolitescomprised both autotrophs (Rhodomonas sp., Dunaliella salina,Thalassiosira weissflogii) and heterotrophs (Oxyrrhis marina,Amphidinium crassum, Rimostrombidium caudatum). Observed effectsincluded immobilisation (e.g. of O. marina), morphological changes(e.g. in D. salina) and/or aberrant behaviour (e.g. of R. caudatum),mainly as preliminary stages of cell lysis. Immobilization andlytic effects against O. marina were strongly dependent on A.ostenfeldii cell concentrations. Effects also differed substantiallyamong strains and different batch cultures of the same strain.Values of EC₅₀, defined as the A. ostenfeldii cell concentrationcausing lysis of 50% of O. marina cells, ranged from 0.3 to1.9 x 10³ mL^–1, depending on the A. ostenfeldii strain.The autotrophic dinoflagellate Scrippsiella trochoidea reactedto exposure to A. ostenfeldii cells by formation of temporary(ecdysal) cysts, whereas, in contrast, the flagellates Emilianiahuxleyi and Prymnesium parvum and the ciliate Strombidium sp.were relatively refractory or even unaffected. As long as cellsdid not lyse, the fluorescence yield of target autotrophs, estimatedby pulse-amplitude modulation fluorometry, did not significantlychange during the first 3 h of incubation, suggesting that allelochemicalsproduced by A. ostenfeldii caused no short-term negative effectson the photosynthetic apparatus. Overall, the allelochemicalresponses of target species showed no obvious relationship tocell quota or extracellular concentrations of either toxic macrocyclicimines (spirolides) or tetrahydropurine neurotoxins (saxitoxinand analogues) produced by various strains of A. ostenfeldii.Instead, the potency of A. ostenfeldii, eliciting immobilizationand lytic species-specific responses in potential predatorsand competitors, is consistent with the existence of an allelochemicalmechanism unrelated to the bioactivity of known phycotoxinsof the genus Alexandrium.     

Effects of toxic Alexandrium species on the survival and feeding rates of brine shrimp, Artemia salina

Zooplankton is an important link between phytoplankton and higher consumers in the marine food chain. To investigate the harmful effects of the toxic dinoflagellate Alexandrium species on zooplankton, 4 strains of Alexandrium spp., isolated from the Chinese coast, were used to test the species' effects on the survival and feeding rates of the brine shrimp, Artemia salina. The experiment was designed to assess the response of A. salina in each stage of its life cycle: nauplii, metanauplii, and adult. Each experiment was conducted in a 500 ml treatment that was added. The toxic treatments consisted of single strains of A. minutum, A. catanella, and A. tamarense (Nanhai and Donghai strain), while non-toxic species (dinoflagellate Prorocentrum donghaiense and diatom Chaetoceros minutissimus) were used as control treatments. An additional phytoplankton treatment consisted of, a mixture of A. tamarense (Nanhai strain) and P. donghaiense. Alexandrium spp. species were found to have lethal effects on the brine shrimp at a density of 2000 cells/ml. All the brine shrimps died within 24-168 hours of inoculation with the 4 treatments each containing single toxic Alexandrium species. During the feeding experiment, toxic Alexandrium spp. caused a reduction in the feeding rates in all the three stages of the life cycle of A. salina, whereas this response was not obvious in the treatment involving the nontoxic species P. donghaiense. The body surface of the brine shrimp that were fed on Alexandrium species was consistently covered by a sticky floc. Mortality of A. salina was observed to increase with the occurrence of the floc. The toxicity of the paralytic shellfish poisons (PSP) produced by the Alexandrium species was not significantly correlated with the survival or the feeding rate of the brine shrimp. When A. tamarense was mixed with P. donghaiense, the lethal effect of A. tamarense decreased, as shown by an increase in the survival and the feeding rates of the brine shrimp. A. salina metanauplii were found at the life stage most sensitive to the toxic algae and hunger. In summary, toxic Alexandrium spp. were found to have lethal effects on A. salina and to restrain the brine shrimp's feeding rate. Nontoxic Prorocentrum mitigated the toxicity of Alexandrium to a certain extent. The results also imply that the sticky material on the surface of the body of the brine shrimp may have been an important lethal factor rather than the PSP toxins.