【作者】 吕淑果；

【导师】 韩博平； 王旭晨；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋生物学， 2009， 博士

【摘要】 研究初级食物供给与初级消费之间数量与质量的关系在海洋浮游生态系统食物网研究中占有基础地位。悬浮颗粒物及浮游动物中脂肪酸的组成和含量可以很好地为食物关系研究提供信息。当悬浮颗粒物在时空上存在数量和质量差异时,这种差异就可能在浮游动物中体现出来,而且通过脂肪酸的信息可以追踪到这种差异。本研究旨在阐明脂肪酸在悬浮颗粒物组成中的生物标记作用和在悬浮颗粒物到浮游动物食物传递过程中的营养指示作用,同时应用这一标记物研究胶州湾海域悬浮颗粒物的大体分布及其与浮游动物间的食物关系。文章首先依据2005年3月-2006年2月胶州湾颗粒有机碳及叶绿素a的数据估测碳生物量的转化系数,发现该系数受时空环境差异的影响,平均为56,从而推导出胶州湾浮游植物有机碳浓度,进而探讨浮游植物对颗粒有机碳的贡献。对各参数分析结果显示胶州湾颗粒有机碳、叶绿素a和浮游植物有机碳年平均浓度分别为为0.47 mg.L-1、4.16μg.L-1及0.23 mg.L-1,三者表现出相似的时空变化动态,即湾内沿岸水域较高,湾外较低,夏季较高秋冬季较低。浮游植物对颗粒有机碳的贡献较高,年平均接近37%。对悬浮颗粒物的脂肪酸组成分析后发现饱和脂肪酸(SSFA)16:0,14:0,18:0及单不饱和脂肪酸(MUFA)Σ16:1(ω7+ω5+ω9)所占比例较高,多不饱和脂肪酸(PUFA)中EPA和DHA也相对较高。总脂肪酸在水体中的绝对浓度及在颗粒有机碳中的相对含量均存在着时空变异,二者的平均变动范围分别在4.7-60.2μg . L-1及20.1-86.7μg . mg-1之间,夏季高于秋冬季,空间分布上二者均在湾东部相对较高,而在湾外较低。不同脂肪酸组合的时空变化可以反映出悬浮颗粒物组成的时空动态,其中16:1ω7/18:1ω9、Σ16:1/18:1ω9、Σ16:1/Σ18:1、Σ16/Σ18、Σ16/ΣFA及20:5ω3/22:6ω3等脂肪酸组合在研究海域可以较好的指示硅藻组成,而Σ18/ΣFA及22:6ω3/ΣFA可以指示甲藻组成,BSFA/ΣFA、Σ(Br+St)/ΣFA、Br/St (15:0)及Br/St (15:0+17:0)可以较好的指示细菌,SSFA/ΣFA及(24:0+26:0)/ΣFA可以示踪碎屑组分及其中的陆源成份。ω3系列脂肪酸在有机碳中的含量及在总脂肪酸中的比例以及不饱和指数可以表征悬浮颗粒物的食物质量。通过标志脂肪酸对悬浮颗粒物组成的指示发现冬季2月悬浮颗粒物组成中硅藻所占比例较高,多数月份湾内近岸水域尤其是湾东部细菌组成相对较高,而湾口至湾外水域碎屑含量相对较高。浮游动物总平均干重生物量为72.6 mg.m-3,平面分布表现为湾内北部及中心区域生物量普遍较高,湾东部水域较低,季节变化表现为总生物量在春季4月及冬季12月形成峰值,总体上在春季5月、夏季7月及秋冬大部分月份相对较低,但不同粒径组成其动态不尽相同。浮游动物的脂肪酸组成与悬浮颗粒物存在一定差别,表现为MUFA比例下降,PUFA比例升高;SSFA中14:0的比例下降,18:0及20:0比例提高,MUFA中20:1ω9比例升高,PUFA中,EPA及DHA所占比例也相对较高。8月份总脂肪酸含量较高,9月与10月相对较小,各粒级内差别不大。利用主成份分析发现悬浮颗粒物的组分在浮游动物中能够用相应脂肪酸指标进行示踪,当食物数量充分满足需求时,浮游动物脂肪酸特征与悬浮颗粒物组成一致性较高,同时通过脂肪酸示踪发现当潜在食物数量较丰富时,浮游动物的摄食存在选择性,这种选择可能受食物质量的调控,而当食物数量较低时,其选择性也降低。悬浮颗粒物中EPA含量及不饱和指数是相对重要的食物质量指示物,通过对其指示特征的分析发现胶州湾总体上浮游动物的摄食会影响其食物质量组成;但在8月,浮游动物的生物量受悬浮颗粒物质量的调控,而浮游动物生物量对食物数量的摄食压力较小,认为该时期是食物质量限制对浮游动物生物量影响相对重要的时期,可以用特征脂肪酸进行清晰的分析。更多还原

【Abstract】 Quantity and quality of food on its consumers are crucial in regulation of food webs in marine pelagic systems. Fatty acid profile is able to provide useful information to trace trophic transfer from food seston to zooplankton. If it really exists difference in food quality of seston, the difference can be recognized from the variation of fatty acid compositon in higher trophic level organisms. The aim of the present study was to investigate the distribution of seston fatty acids in a eutrophic bay, Jaiozhou Bay in Northern China, and try to know their transfer up to zooplankton consumers.Seston and zooplankton were collected from fourteen sampling stations from 2005 to 2006 in the studied bay. The zooplankton was grouped into two size fractions: 160-500μm and >500μm. Particulate organic carbon, chlorophyll-a, dry biomass of zooplankton, fatty acids of seston and zooplankton were measured.Based on the field measurements of Chl-a and POC concentrations, a mean value of 56μg.μg–1 of conversion ratios of Phyto-C to Chl-a was generated with using of the linear regression model II. The contribuition to TOC by phytoplankton can be estimated. The mean concentrations of POC, Chl-a and Phyto-C were 0.47 mg.L-1, 4.16μg.L-1 and 0.23 mg.L-1, respectively. They showed the similar temporal and spatial dynamics and were higher in edge region and in summer, lower in the outer bay and in autumn and winter. The mean distribution of phy-C to POC reached 37%.The fatty acid composition of seston from collected samples included SSFA, BSFA, MUFA and PUFA. The SSFA was one dominant group, and mainly composed of 16:0, 14:0 and 18:0. The MUFA and PUFA were mainly composed ofΣ16:1(ω7+ω5+ω9) and EPA+DHA, respectively. The total concentration of fatty acids in water and in POC ranged temporally 4.7-60.2μg . L-1 and 20.1-86.7μg . mg-1, and higher in summer than in autumn and winter. They were, spatially, higher in the northeast zone of the bay than in the outer bay. In Jiaozhou Bay, 16:1ω7/18:1ω9,Σ16:1/18:1ω9,Σ16:1/Σ18:1,Σ16/Σ18,Σ16/ΣFA and 20:5ω3/22:6ω3 are the specific fatty acids for the biomarkers of diatom, theΣ18/ΣFA and 22:6ω3/ΣFA are for flagellate, BSFA/ΣFA,Σ(Br+St)/ΣFA, Br/St (15:0) and Br/St (15:0+17:0) for bacteria and SSFA/ΣFA and (24:0+26:0)/ΣFA for detritus and the terrestrial resource. The contents and percents ofω3-fatty acids and the unsaturation index are good at indicating the food quality. By using these fatty acid biomarkers, diatom was recognized to be dominant in seston in Feb. 2005, bacteria was relatively high in near-shore region especial in east region, and the detritus higher in bay mouth and the outer bay.The biomass of total zooplankton (>160μm) was higher in the north and central regions and in April and December than in east region and in May, July and months of autumn and winter, spatially and temporally, and with a mean value of 72.6 mg.m-3, but distinct spatial and temporal dynamics with size classses of zooplankton was observed. Fatty acid profile of zooplankton was obviously different from that of seston. Among total fatty acid of zooplankton, the percent of MUFA decreased while that of PUFA increased;14:0 decreased in SSFA while 18:0 and 20:0 increase, 20:1ω9 increased in MUFA , EPA and DHA increase significantly in PUFA. The content of fatty acids in zooplankton was higher in August than in September and October.According to the principal component analysis (PCA), using fatty acid trophic markers such asΣ16:1/Σ18:1, BSFA/ΣFA and SSFA/ΣFA, it is able to trace the compositions of seston up into herbivorous zooplankton. The fatty acid compositions of consumers are similar to the marked compositions of seston when total food resource significantly exceeded the requirement of the zooplankton consumers. Feeding selectivity of zooplankton controlled by the food quality can be identified from the correlation of zooplankton to their food quality when food quantity is well above the saturation level. However, when the food quantity decreased, the food selectivity of zooplankton was limited.The content of EPA and unsaturation index of seston were two good food quality markers, the consumption of zooplankton can exert a high pressure on the food quality in all in Jiaozhou Bay. In August, however, the zooplankton biomass was controlled by the seston quality while the grazing pressure by zooplankton decreased. We suggest that food quality constraints are important in August in Jiaozhou Bay, and the fatty acid composition in this period provides useful information for investigating the seston food quality constraints on biomass of zooplankton consumers.更多还原