【作者】 许思思；

【导师】 宋金明； 孙培艳；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 环境科学， 2011， 博士

【摘要】 本文以受人类活动影响显著的渤海为研究对象,通过调查和对历史资料的集成研究,探讨了20世纪80年代以来渤海氮、磷变化及其对浮游植物的影响;以真鲷、黑鲷、日本对虾、四角蛤蜊和毛蚶等渤海常见渔业资源生物作为生物指标种,运用加速生命试验法模型、复合污染效应加和模型和不同生活史生物幼体阶段存活率与其种群增长率之间的关系,估算了渤海近岸海域海水镉、汞、铅和石油烃复合污染对渤海常见鱼类、甲壳类和双壳类长期死亡率和种群增长率的影响;并运用Ecopath生态通道模型揭示了近50年来渔业捕捞对渤海生态系统的影响;剖析了近50年来渤海渔业资源的深刻变化特征,获得了一系列新的结果和认识。主要结论如下:1.渤海海水中氮浓度的增加、磷浓度的降低导致更易受磷限制的角毛藻属优势地位降低、而更易受氮限制的梭状角藻和叉状角藻等不利于高营养级渔业资源生物生长的浮游植物种类优势地位升高,渤海湾海水镉、汞、铅和石油烃复合污染导致渤海常见渔业资源生物的种群增长率明显降低,氮、磷、重金属和石油烃污染是导致渤海渔业资源衰退的重要原因之一。环渤海地区污水处理量、农用化肥的施用量和黄河入海径流量对近30年来渤海氮、磷变化具有显著的影响。渤海氮、磷变化致使浮游植物生长的限制性营养盐由20世纪80年代早期的氮限制、20世纪80年代末期的氮-磷共同限制转变为20世纪90年代以来的磷限制。运用半饱和吸收常数研究发现,20世纪80年代以来,具有较高的磷酸盐半饱和吸收常数和较低的硝酸盐半饱和吸收常数的浮游植物优势种(如角毛藻)优势地位下降,而具有较低的磷酸盐半饱和吸收常数和较高的硝酸盐半饱和吸收常数的浮游植物优势种(如梭状角藻和叉状角藻)优势地位升高。浮游植物群落结构朝着对高营养级渔业资源生物不利的方向发展。加速生命试验法模型(Accelerated Life Testing model)结果显示,1996-2005年渤海湾近岸海域海水镉、汞和铅平均浓度均已超过其对渤海湾常见渔业资源生物的安全浓度;在1996-2005年渤海湾近岸海域海水镉、汞、铅和石油烃平均浓度下,鱼类的长期死亡率分别为4.5%、16.3%、0.0%和12.0%,甲壳类的长期死亡率分别为0.4%、7.9%、0.3%和6.6%,双壳类的长期死亡率分别为10.5%、0.2%、0.2%和2.3%。效应加和模型(Independent Action model)的估算表明,在镉、汞、铅和石油烃组成的复合污染条件下,渤海湾常见鱼类、甲壳类和双壳类的长期死亡率分别为29.7%、14.6%和12.9%,其种群增长率分别降低约6.4%、14.6%和12.9%。复合污染是导致渤海湾渔业资源衰退的重要因素。2.渔业捕捞通过改变渤海生态系统关键功能组、降低生态系统的能量传递效率以及减弱生态系统的负反馈作用和稳定性,导致渤海生态系统特别是较高营养级渔业生物种群的重大失调,渔业捕捞是导致渤海渔业资源衰退的重要因素。Ecopath生态通道模型显示,由于过度的渔业捕捞,渤海生态系统最关键的功能组已由20世纪50年代末的高营养级游泳动物食性鱼类,转变为20世纪80年代初和20世纪90年代中等营养级的底栖大型甲壳类。近50年来渤海生态系统的能量传递效率在波动中显著下降,尤其以第二营养级和第三营养级能量传递效率的下降最为明显。近50年来渤海生态系统的总能流量、总生物量、流向碎屑的能流量、TPP/TR值、费恩循环指数、费恩路径长度和生态网络的聚合度等均呈现较大的波动,渤海生态系统的TPP/TR值都明显大于1。日益增长的捕捞强度导致渤海生态系统负反馈调节功能降低,目前渤海生态系统处于不稳定期。3.近几十年来渤海底栖食物链渔业资源衰退明显,渤海捕捞渔获物平均营养级处于下降趋势。淡水输入量、上行生物饵料提供量与水体硅的减少以及水体氮磷比与铅的增加直接或间接导致了捕捞渔获物平均营养级的降低。将20世纪50年代末以来,渤海生态系统食物网简化为浮游食物链、底栖食物链和碎屑食物链三条食物链。浮游食物链渔业资源已取代底栖食物链渔业资源成为最主要的渔业资源,碎屑食物链渔业资源生物量百分比呈上升趋势,近年来已成为继浮游食物链渔业资源的第二大类渔业资源。渔业捕捞、渤海次级生产力结构的变化是导致渤海主要渔业资源结构变化的重要因素。1956-2000年间,渤海捕捞渔获物平均营养级(Y)与公元年份(X)具有Y=-0.008X+19.777(R=-0.710,n=41,sig.=0.000)的统计关系,渤海捕捞渔获物平均营养级每年下降约0.01。20世纪50年代中期以来,渤海生态系统内部较高营养级渔业资源生物群落的衰退和较低营养级渔业资源生物群落相对生物量的增加是造成捕捞渔获物平均营养级降低的根本原因。淡水输入量、硅浓度和上行生物饵料提供量的降低以及N/P比和铅浓度的升高通过直接或间接影响渤海生态系统内部主要渔业资源结构变化进而导致了渤海捕捞渔获物平均营养级的降低。4.人类活动排污已对渤海湾浮游植物群落和底栖动物群落的多样性产生明显影响。环境污染引起的底栖动物群落多样性的降低可进而导致渤海湾底栖动物食性鱼类的衰退。2008年4月渤海湾浮游植物仍以硅藻为主;甲藻细胞丰度百分比较低,其高值区位于渤海湾口南北沿岸直接或间接受滦河或黄河径流输入的影响较为显著的区域,磷酸盐是影响硅藻和甲藻细胞丰度百分比的重要因素。2008年4月渤海湾浮游植物群落多样性和物种丰富度有较为一致的分布,磷酸盐、铬和汞是直接或间接影响浮游植物群落多样性和物种丰富度的重要因素。综合运用底栖动物群落多样性指数、种类个体的对数正态分布和K-优势度曲线等方法的评价结果表明,2008年4月渤海湾污染较重的海域主要位于曹妃甸港口邻近海域、黄骅港邻近海域和渤海湾口邻近黄河口的海域等直接或间接地受人类活动较大影响的海域。人类活动排污引起的底栖动物群落多样性的降低可进而导致渤海湾底栖动物食性鱼类的衰退。1998年至2006年渤海湾平均网产渔业资源量明显降低,营养级较高的底栖动物食性鱼类的优势地位已逐渐被较低营养级的浮游动物食性鱼类和底栖动物所代替,渔业资源生物平均营养级表现为下降的趋势,渔业资源呈现继续衰退的趋势。更多还原

【Abstract】 Based on the integrated research on the data investigated by our laboratory and the historical data in recent decades in the Bohai Sea which was significantly affected by anthropogenic activities, systematic studies on the changes in dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) and their effects on phytoplankton over the last 30 years in the Bohai Sea were presented; using Accelerated Life Testing model, Independent Action model and the relationship between reduction in the juvenile survival rate and reduction in population growth rate, this paper estimated the long-term lethality of combined pollution of Cd, Hg, Pb and PHs in the Bohai Bay to common fishery species (such as Pagrosomus major, Sparus macrocephlus, Penaeus japonicus, Mactra quadrangularis and Scapharca subcrenata), and the corresponding reduction of population growth rate of such common fishery species; impact on the Bohai Sea ecosystem by fishing over the last 50 years was investigated quantitatively using the Ecopath model; the variation characteristics of the fishery resources of the Bohai Sea in recent decades were analyzed. Series of new results were obtained. The main conclusions were as follows:1. The increasing concentration of nitrogen and the decreasing concentration of phosphorus resulted in the decrease of dominance of Chaetoceros spp. which was prone to be limited by phosphorus and the increase of dominance of Ceratium fusus and Ceratium furca which were prone to be limited by nitrogen. The combined pollution of Cd, Hg, Pb and petroleum hydrocarbons (PHs) caused the notable reduction of population growth rates of common fishery species in the Bohai Sea. Pollution of nitrogen, phosphorus, heavy metals and PHs was one of the important factors influencing the fishery decline in the Bohai Sea.The amount of sewage disposal and use of fertilizer in the surrounding regions of the Bohai Sea, and the Yellow River runoff were found to have a significant influence on the DIN or DIP concentrations in the Bohai Sea over the last 30 years. Changes in DIN and DIP resulted in changes in the limiting nutrients of phytoplankton in the Bohai Sea from nitrogen in the early 1980s to nitrogen-phosphorus in the late 1980s, and then to phosphorus after the 1990s. The half saturation constant (Ks) was used to evaluate the effect of nitrogen and phosphorus on the phytoplankton community structure in the Bohai Sea over the last 30 years. Cell abundance percentages of dominant phytoplankton species with high Ks values for phosphorus and low Ks values for nitrogen have decreased since the 1980s, while those of dominant phytoplankton species with low Ks values for phosphorus and high Ks values for nitrogen increased during this period. Phytoplankton community is going against the fishery species with high trophic levels in the Bohai Sea.Accelerated Life Testing model showed that the annual mean concentrations of Cd, Hg and Pb in seawaters of the Bohai Bay during 1996-2005 were higher than their safe concentrations to common fishery species in the Bohai Bay. The long-term lethality of mean concentrations of Cd, Hg, Pb and PHs in seawaters of the Bohai Bay during 1996-2005 to fishes was 4.5%, 16.3%, 0.0% and 12.0%, respectively, that to crustaceans was 0.4%, 7.9%, 0.3% and 6.6%, respectively, and that to bivalves was 10.5%, 0.2%, 0.2% and 2.3%, respectively. Using Independent Action model, it was estimated that the long-term lethality of Cd, Hg, Pb and PHs to fishes, crustaceans and bivalves was 29.7%, 14.6% and 12.9%, respectively, which resulted in the reduction of population growth rate by about 6.4%, 14.6% and 12.9%, respectively. Combined pollution was an important factor affecting the fishery decline in the Bohai Bay.2. Fishing activities caused the imbalance of the Bohai Sea ecosystem especially the fishery species with higher trohpic levels by changing the key functional group and decreasing the energy transfer efficiency of the Bohai Sea ecosystem, and by reducing the negative feedback function ability and the stability of the Bohai Sea ecosystem. Fishing was the important factor influencing the fishery decline in the Bohai Sea.The Ecopath models showed that because of the over fishing, the most key functional groups of the Bohai Sea ecosystem changed from high trophic level fishes of nekton feeding habits in the late 1950s, to macro benthic crustaceans with medium trophic levels in the early 1980s and in the 1990s. The energy transfer efficiency of the Bohai Sea ecosystem, especially that of organisms at the second and the third trophic levels, decreased notably with fluctuations. The total system throughput, total biomass, sum of all flows into detritus, total primary production/total respiration (TPP/TR), the Finn’s mean cycling index, Finn’s mean path length and Ascendency exhibited great fluctuations in rencent decades. The TPP/TR was notable larger than 1. The increasing fishing activities resulted in the decrease of the negative feedback function ability of the Bohai Sea ecosystem. At present the Bohai Sea ecosystem is in the unstable period.3. Fishery species based on the benthic food chain declined significantly in recent decades. The mean trophic level of primary fishery landings exhited a decreasing trend during 1956-2000 in the Bohai Sea; the decrease of freshwater input, supply of food organisms and Si, and the increase of N/P ratio and Pb caused such decrease directly or indirectly.The food web in the Bohai Sea ecosystem was simplified into the pelagic food chain, the benthic food chain and the detritus food chain. Fisheries based on the pelagic food chain has replaced those based on the benthic food chain and became the first primary fisheries in the Bohai Sea since the 1ate 1950s. Biomass percentage of fisheries based on the detritus food chain increased continuously and became the second primary fisheries in the Bohai Sea in recent years. Fishing activities and change of structure of secondary production were the important factors influencing the change of the structure of major fishery resources in the Bohai Sea.There was an linear relationship between the mean trophic level of primary fishery landings (Y) and the year (X) during 1956-2000 (Y=-0.008X+19.777; R=-0.710, n=41, sig.=0.000), and that the mean trophic level of primary fishery landings decreased about 0.01 per year. The decline of fishery species with higher trophic levels and the increase of relative biomass of the fishery species with lower trophic levels in the Bohai Sea ecosystem were the root causes of the decreae of the mean trophic level of primary fishery landings in the Bohai Sea. The decrease of freshwater input, supply of food organisms and Si and the increase of N/P ratio and Pb caused direactly or indirectly the decrease of mean trophic level of primary fishery landings by changing the main fishery community structure in the Bohai Sea.4. Anthopogenic pollution has caused notable effects on the species diversity of the phytoplankton community and benthos community in the Bohai Bay. The decrease of benthos community diverysity caused by environmental pollution can further cause the decline of fishes with benthos feeding habit.Diatoms were also the primary component of phytoplankton community in the Bohai Bay in April 2008, and the cell abundance percentage of dinoflagellates was relatively low during the same period. The north and south part of the Bohai Bay mouth, which were affected directly or indirectly by the runoff of the Luanhe River and the Yellow River, respectively, had relative high cell abundance percentage of dinoflagellates. Phosphate concentration was an important factor influencing the ratio of cell abundance of diatoms to that of dinoflagellates. Species diversity and richness of phytoplankton community had the similar spatial distribution in the Bohai Bay in April 2008. Concentrations of phosphate, Cr and Hg were important factors affecting directly or indirectly species diversity and richness of phytoplankton community.Using biodiversity index, lognormal distribution of species individuals and K-dominance curves of the benthos community, assessment of the marine environment quality in the Bohai Bay in April 2008 indicated that the sea areas that were polluted more heavily located in the adjacent waters of Caofeidian Harbor and Huanghua Harbor, and the Bohai Bay mouth near to the Yellow River mouth. The three sea waters were affected greatly by anthropogenic activities. The decrease of benthic community diverysity caused by anthropogenic pollution can further cause the decline of fishes with benthos feeding habit.The average productions of fishery resources decreased notably in the Bohai Bay during 1998-2006. The dominance of benthos feeding habit fishes which were of higher trophic levels had been replaced by nekton feeding habit fishes that were of lower trophic levels. The mean trophic level of fishery resources in the Bohai Bay exhibited a decreasing trend. The fishery resources exhibited a trend of continuous decline.更多还原