【作者】 孙百晔；

【导师】 王修林；

【作者基本信息】 中国海洋大学 ， 环境科学， 2008， 博士

【摘要】 海洋赤潮问题已经成为困扰世界沿海国家的重要环境问题之一。本论文针对长江口及邻近海域赤潮发生机制研究,为阐述光照效应在该海域赤潮发生中的作用,应用现场培养实验与模拟计算相结合的方法,着重研究了该海域典型赤潮生物[中肋骨条藻(Skeletonema Costatum Cleve)和东海原甲藻(Prorocentrum donghaiense Lu)]生长的光照效应。应用现场培养实验方法,测定了该海域主要赤潮生物中肋骨条藻、东海原甲藻等7种浮游植物生长的最适光照及相关温度效应,并在浮游植物生长光照模型的基础上,改进了水生生态系统浮游植物生物量分布光照效应的半定量评价方法,并据此对长江口及邻近海域2种重要赤潮藻(东海原甲藻和中肋骨条藻)生物量的垂直分布、平面分布与光照的关系进行了研究;进一步利用长期序列资料,探讨了近50a来光照效应与长江口及邻近海域浮游植物生物量年代变化规律的关系。主要得出如下结论:1)改进的水生生态系统浮游植物生长光照效应分析法是建立在浮游植物光照效应模型的基础上,综合反映了浮游植物生长特性和海水中的光照特性。“浮游植物生长光效水柱累积指数”指标可以用于半定量分析浮游植物平面分布的光照效应;生长的“最适光效深度”指标,辅以浮游植物生长光效指数的断面分布可以用于半定量分析浮游植物垂直分布的光照效应。2)证实了在长江口及邻近海域,在营养盐、温度等环境因子适宜的情况下,海水中的光照强度是限制赤潮进一步向近岸方向扩展的关键因素。用生长光照效应分析法,结合现场培养实验得到的生长参数进行的模拟计算发现,浮游植物生长光效水柱累积指数由近岸向远岸逐渐增加,与调查结果的比较表明,光照是限制长江口及邻近海域浮游植物生物量高值区向近岸方向扩展的关键因素。赤潮在“赤潮高发区”这个特定海域发生是水体光照和营养盐权衡的结果。3)光照的适宜性是中肋骨条藻(Skeletonema Costatum Cleve)和东海原甲藻(Prorocentrum donghaiense Lu)分别在表层和次表层大量繁殖,形成高密度区进而发展成为赤潮的重要原因之一。用生长光照效应分析法,结合现场培养实验得到的生长参数进行的模拟计算发现,中肋骨条藻生长的最适光效深度位于0.4m左右的表层,东海原甲藻的位于水深4m左右(春夏季节)的次表层;这与调查中发现的中肋骨条藻的高密度区经常在表层,东海原甲藻的高密度区经常在次表层一致。这表明在营养盐等其它因子适宜时,光照的适宜性是中肋骨条藻和东海原甲藻分别在表层和次表层大量繁殖,形成高密度区进而发展为赤潮的重要原因之一。4)自20世纪50年代末至21世纪初,长江口及邻近海域海面太阳辐射与浮游植物生物量的年代变化规律有一定的相关性,光照效应对浮游植物生物量的长期波动规律有一定影响。长江口及邻近海域CDNet-PPT、Chl-aSur、Chl-aEu、PP的年代变化规律与海面太阳辐射之间存在相关性,特别是年均Chl-aSur、Chl-aEu、PP三者与海面太阳辐射之间具有显著或极显著的线性相关关系(依次为p<0.01,p<0.05,p<0.05);而且年均CDNet-PPT、Chl-aSur、Chl-aEu、PP与海面太阳辐射波动规律存在一定的相似性,根据夹角余弦计算的相似性系数分别为0.53、0.66、0.81、0.57。这种高相关性在一定程度上说明,光照效应对浮游植物生物量长期波动规律有一定影响。总之,通过综合分析长江口及邻近海域浮游植物生物量平面分布、垂直分布和年代变化的光照效应,证明光照是影响该海域赤潮发生的重要因素。改进的“浮游植物生长光照效应分析法”可以用于海洋、湖泊浮游植物生态学研究,对水生生态系统中浮游植物生长光照效应研究具有重要意义。论文所得到的研究结果,对深入认识该海域赤潮发生机制有重要学术价值,对该海域赤潮发生控制过程研究有重要意义。更多还原

【Abstract】 Harmful algal blooms (HAB) has been one of the important environmental problems worry the coastal countries. Aimed at the HAB mechanisms study and in order to expatiate effects of irradiance on HAB occurrences in the Changjiang Estuary and Adjacent Coastal Waters, with field culture experiments and model calculations, effects of irradiance on growth of 2 species of importance harmful algae (Skeletonema Costatum Cleve and Prorocentrum donghaiense Lu) were studied. Firstly, the optimal light intensity (Iopt) of 7 species of harmful algae and the relative temperature effects were measured with field culture experiments. Then, a method analyzing the effects of irradiance on phytoplankton growth was improved on based on the light-growth model of phytoplankton. Using this method, the relationship between irradiance and vertical and horizontal distribution of Skeletonema Costatum Cleve and Prorocentrum donghaiense Lu were analyzed. Finally, the relationship between irradiance and phytoplankton biomass during the last nearly 50 years was discussed by use of long-term series data. The main results are as the following:1.“Phytoplankton growth light-effect analysis method”is modified based on phytoplankton growth-light model, which combines phytoplankton growth characteristics and irradiance characteristics under sea water. With this modified method, light effects on horizontal distribution of phytoplankton can be measured using the so-called“phytoplankton-growth light-effect water-column-accumulation index”; and light effects on vertical distribution of phytoplankton can be measured using the index“optimal light-effect depth”.2. It is confirmed that irradiance in sea water, without the limiting of nutrition, temperature, and other environmental factors, is the key factor to prevent red tides from extending more to the inshore area in the Changjiang Estuary and Adjacent Coastal Waters.By the phytoplankton growth light-effect analysis method, with growth parameters obtained from field culture experiments, light effects on phytoplankton horizontal distribution were measured. It is indicated that irradiance in sea water, without the limiting of nutrition, temperature, and other environmental factors, is the key factor to prevent red tides from extending more to the inshore area in the Changjiang Estuary and Adjacent Coastal Waters, by comparing the calculated growth light-effect, which is that“phytoplankton-growth light-effect water-column-accumulation index”increases from inshore to offshore, with the vessel investigation results carried out in this sea area. In fact, it is the trade-off of light and nutrient fitness that results in blooms in the so called red tide area.3. Light-optimum characteristics in surface and subsurface water is an important factor for S. Costatum and P. donghaiense to reproduce so rapidly in surface and subsurface water, respectively, as to blooms occurring.By the phytoplankton growth light-effect analysis method, with growth parameters obtained from field culture experiments, light effects on phytoplankton vertical distribution were measured. The calculated results show that the optimal light-effect depth for S. Costatum is about 0.4m in the surface water and 4m or so (in spring and summer) in the subsurface water for P. donghaiense, which is consistent with the vessel investigation results that S. Costatum usually blooms in the surface water and P. donghaiense in the subsurface water. The consistency of the calculated light-effect with the investigated data indicates that light-optimum characteristics in surface and subsurface water, without the limitation of nutrition, temperature, and other environmental factors, is an important factor for S. Costatum and P. donghaiense to reproduce rapidly and bloom in surface and subsurface water, respectively.4. From late 1950s to early 2000s, irradiance above sea surface was correlated in some degree with annual phytoplankton biomass in the Changjiang Estuary and Adjacent Coastal Waters.By collecting and analyzing phytoplankton investigation data from late 1950s, especially from 1980s, to early 2000s in this sea area, it is found that phytoplankton biomass (CDNet-PPT, Chl-aSur, Chl-aEu and PP) fluctuated as an“N shape”with a cycle of about 20a, which were correlated with irradiance above sea surface, especially, Chl-aSur, Chl-aEu and PP were closely correlated (p<0.01, p<0.05 and p<0.05, respectively)with irradiance.The author believes that the modified“phytoplankton growth light-effect analysis method”can be applied in marine and lake phytoplankton ecosystem, the above results are of significance for understanding the mechanisms of HAB occurrence in the Changjiang Estuary and Adjacent Coastal Waters, as well as for the prevention and control of HABs in this sea area.更多还原