【作者】 刘梦坛；

【导师】 孙松； 李超伦；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋生态学， 2010， 博士

【摘要】 脂肪酸是海洋生物体内一种重要的生物大分子，它在生物体内不仅具有重要的生理作用，还能被用来作为标记指示海洋生物的食物组成和食物质量的好坏。本文首先研究了硅藻和甲藻的脂肪酸组成特征，并以单种微藻培养中华哲水蚤以验证脂肪酸作为标记指示浮游动物摄食的可行性。随后以脂肪酸作为标记研究了胶州湾和黄海浮游生态系统的关键营养过程，并从食物网的角度研究了物质和能量从浮游植物经浮游动物向鱼类等捕食者进行传递的过程，进一步阐明了黄海生态系统食物网的营养关系。对单种微藻脂肪酸组成的研究表明，锥状斯氏藻C Scrippsiella trochoidea)和海洋原甲藻(Proroceutrmn micaus)的主要脂肪酸有16:0,18:4w3,18:5w3,20:3w6,22:6w3，中肋骨条藻( Skeletouema costatm)和角毛藻Chaetoceros sp.)的主要脂肪酸为14:0, 16:0, 16:1c}7, 20:Sc}3。两种甲藻和两种硅藻分别都表现出典型的甲藻门和硅藻门的脂肪酸特征。在此基础上以饥饿培养为对照，以海洋原甲藻CProroceutrmn micaus)和中肋骨条藻C Skeletouema costatmn培养胶州湾的浮游动物优势种一一中华哲水蚤C Cala}tus si}ticus )。虽然中华哲水蚤对不同脂肪酸的吸收和转化效率不同，但脂肪酸标记还是成功的指示了中华哲水蚤对微藻的摄食。在饥饿培养中，首先消耗的是那些浮游动物自身不能合成的多不饱和脂肪酸，Ifu结构脂肪酸都表现出了较高的保守性。结合各脂肪酸标记的变化趋势和Pearson相关性分析的结果认为，18:4c}3, 18:4c}3/16:1c}7, }18/}16能较好的指示中华哲水蚤对海洋原甲藻的摄食，仅16:1c}7/18:4c}3能较好的指示中华哲水蚤对中肋骨条藻的摄食。分析了2007年11月至2008年11月胶州湾颗粒悬浮物和中华哲水蚤脂肪酸组成的时空分布特征，以研究中华哲水蚤食物状况的时空变化以及中华哲水蚤和颗粒悬浮物之间的营养关系。颗粒悬浮物总脂肪酸与叶绿素“显著正相关，表明浮游植物是颗粒悬浮物的重要组分，此外，有机碎屑、纤毛虫、细菌等对颗粒悬浮物也具有重要的贡献。从颗粒悬浮物脂肪酸组成来看，硅藻对胶州湾东北部(AS站)的贡献最大，对湾外(D7站)的贡献最小。相对来说，湾东北部(AS站)颗粒悬浮物的脂类营养物质含量要高十湾中部(C3站)和湾外(D7站)。从主成分分析来看，2008年7月AS和C3两站具有不同十其他月份和站位的特点。其颗粒悬浮物中甲藻含量较高，目颗粒悬浮物的脂类营养物质丰富。各脂肪酸标记的变化指示了颗粒悬浮物中各组分的变化。胶州湾的硅藻水华在春季和夏季均有出现，Ifu甲藻水华则出现在夏季。随着水华的发生，颗粒悬浮物脂类营养物质也增多。中华哲水蚤脂肪酸组成对春季水华存在明显的响应，但时间上有所滞后。中华哲水蚤体内必需脂肪酸20:5w3和22:6w3的含量占总脂肪酸的50%以上，远高十极区的挠足类。另外，其体内16:1c}7的含量远高十18:4w3，说明胶州湾中华哲水蚤摄食的主要浮游植物是硅藻。但与极区挠足类相比，中华哲水蚤20:1+22:1脂肪酸的含量较低，说明其植食性程度并不高。除浮游植物之外，中华哲水蚤具有一个包括有机碎屑、卵、细菌、纤毛虫在内的广泛的食谱。研究了2006年12月、2007年3月、5月和8月黄海颗粒悬浮物和中华哲水蚤脂肪酸组成的时空分布特征。黄海颗粒悬浮物总脂肪酸含量、硅藻标记、甲藻标记、PUFA和艺w3脂肪酸表现出相似的时空分布特征。在春季3月和5月，这些脂肪酸标记的含量要高十其他季节。说明春季黄海浮游植物比较丰富，颗粒悬浮物的脂类营养物质也相对较高。从空间上来看，调查区域中部海区这些脂肪酸标记的浓度要低十北部和南部的海区。说明中部海区颗粒悬浮物中浮游植物相对较小，脂类营养物质也相对较少。与胶州湾相比，黄海的中华哲水蚤多不饱和脂肪酸和艺w3脂肪酸(特别是20:5w3和22:6c}3的含量明显较低，Ifu 20:1+22:1的含量则偏高。说明黄海中华哲水蚤植食性的程度要高十胶州湾。中华哲水蚤雌体产卵率与其体内的16:1c}7,艺16和20:5w3呈正相关关系。从脂肪酸的角度证明了浮游植物(特别是硅藻)对中华哲水蚤繁殖的重要作用。2009年6月黄海颗粒悬浮物脂肪酸组成的空间分布与2006年12月一2007年8月几个航次相似。靠近长江口的C04站和调查区域北部的B18站颗粒悬浮物中浮游植物含量较高，目‘具有较高的脂类营养物质。通过对浮游动物脂肪酸组成分析发现，中华哲水蚤雌体和挠足幼体均具有植食性特征，但挠足幼体20:1+22:1和18:4w3脂肪酸的含量远高十雌体，说明挠足幼体植食性的程度更高，Ifu b‘更倾向十摄食甲藻。太平洋磷虾18:4w3的含量要高十16:1c}7，说明太平洋磷虾也具有对甲藻的选择性摄食。箭虫体内22:6w3的含量很高，它对食物脂肪酸存在较高的吸收和转化速率，它在浮游动物中处十一个较高的营养级。虫戎体内16:1c}7和18:4w3月旨肪酸的含量较高，表现出显著的植食性特征，另外其体内20:1+22:1月旨肪酸的含量也很高，推测这些脂肪酸都是来自十虫戎类对植食性挠足类的摄食。沙海蛰脂肪酸中15:0+17:0, 22:0+24:0特征明显，说明碎屑对沙海蛰脂肪酸组成具有较大的贡献。从脂类营养物质的角度来看，浮游动物中的中华哲水蚤、太平洋磷虾以及虫戎对浮游动物食性的捕食者来说具有更高的营养价值。应用脂肪酸组成对17种游泳和底栖生物的分析发现，口本崛、壳蜻蝙、鹰爪虾和!脊腹褐虾具有碎屑的特征脂肪酸15:0+17:0和22:0+24:0，这些脂肪酸有可能来自它们对碎屑的直接摄入，也有可能指示了它们对底栖生物的摄食。小黄鱼、星康吉鳗、黑鳃梅童鱼、黄卿脂肪酸含量远高十其他种类，相对来说它们具有较高的脂类营养价值。它们体内16:1c}7和18:4w3脂肪酸的含量均较高，表明它们直接或间接的摄入了大量的植食性浮游动物并目‘对脂肪酸具有较高的吸收和转化率。以往的关十营养关系的研究大多基十“量”的概念。本文初步利用脂肪酸作为标记研究了黄海食物网的营养关系，并以之作为标记反映了黄海食物网中的脂类物质营养价值高低。相对十高纬度海区，利用脂肪酸作为标记对温带海区营养关系的研究要相对复杂一些。在将来的研究中还有必要结合同位素标记等多种方法，以便对生态系统的营养关系进行更全面和准确的研究。更多还原

【Abstract】 As one of the important biological macromolecules, fatty acid plays verymportant roles in marine organisms. Besides, fatty acid could also be used as markersto indicate the feeding of predators. Fatty acid features of diatoms and dinoflagellateswere analyzed. Subsequently, feeding experiment was carried out with the copepodCalauus siuicus using unialgae as diets to verify the validity of fatty acid as markers.Fatty acid markers were then employed in the study of the trophic relationships inJiaozhou Bay and southern Yellow Sea.The fatty acid compositions were analyzed for Scrippsiella trochoidea,Proroceutruin inicaus, Skeletoueina costatuin and Chaetoceros sp二For S. trochoideaand P. micaus, the dominance of 16:0, 18:4c}3, 18:Sc}3, 20:3c}6, 22:6c}3 indicated atypical fatty acid composition of dinoflagellates. For S. costatmn and Chaetoceros sp.,the dominant fatty acids were 14:0,16:0,16:1c}7,20:Sc}3, suggesting a diatom feature.Although the incorporation and turnover rates of dietary fatty acids were differentfrom each other, the feeding experiment could still provide clear evidence for thepotential of specific fatty acids as trophic markers. Polyunsaturated fatty acids whichcannot be synthesized by copepods decreased obviously during the starvationexperiment, while structural fatty acids with more conservative chemical propertieswere consumed in a lesser degree. 18:4c}3, 22:6c}3, 18:4c}3/16:1c}7,∑18/∑16 and22:6w3/20:Sw3 increased in different degrees at the end of the feeding experimentwhen Calauus siuicus was offered with P. micaus. However, the structural fatty acid22:6c}3 was not a suitable marker to indicate the ingestion of dinoflagellate. When thecopepod was fed with S. costatmn, only 22:603 and 16:10}7/18:40}3 increased at the end of the experiment. Based on overall considerations of the variations of these fattymarkers and the Pearson correlation analysis, we deemed that 18:4c}318:4c}3/16:1c}7 and∑18/∑16 were useful markers to reflect the ingestion of P. micausby C. siuicus, and only 16:1c}7/18:4c}3 could be used as marker for the ingestion of S.costatu}n.Seston and the copepod C. siuicus were investigated in Jiaozhou Bay annually inview of their fatty acid compositions. We aimed at elucidating the trophicrelationships between seston and the copepod by depicting the spatial and temporalvariations of their fatty acid compositions. Total fatty acid and Chl a correlatedsignificantly with each other, indicating that phytoplankton was an important sestoncomponents. But it seemed that other particles such as organic detritus, ciliates andbacteria might also contribute a surprising proportion. Principal component analysiswas carried out in this study to ordinate the seston according to stations and months.The results showed that diatom contributed a larger proportion to the northeast ofJiaozhou Bay (AS) than in the middle (C3) and out of the bay (D7). In view of lipidnutrients, seston in the northeast of Jiaozhou Bay showed higher food quality than theother areas. In July 2008, station AS and C3 were different from other cases by higherpercentage of dinoflagellates markers and lipid nutrients. C. siuicus showed atime-delayed response to the spring algae bloom. The essential fatty acids 20:Sc}3 and22:603 were found to occupy a proportion over 50% in C. siuicus, which wassignificantly higher than the polar copepods. 16:1c}7, 18:4c}3 and themonounsaturates 20:1 and 22:1 in C. siuicus verified the herbivorous feeding of thiscopepod. But the comparatively low levels of these fatty acids compared to their polarcounterparts allowed the conclusion to be drawn that besides phytoplankton, C.siuicus might feed on a wider range of particles including organic detritus, eggs,bacteria, small copepods and ciliates, etc.Fatty acid compositions of seston and C. siuicus were analyzed in the southernYellow Sea in December 2006, March, May and August 2007. Total fatty acid, diatommarkers, dinoflagellates markers, PUFA and∑c}3 fatty acid of seston exhibited similar temporal and spatial distributions in the southern Yellow Sea. Phytoplanktonprospered in spring, followed by the increase of these markers in March and May,indicating higher lipid nutrients in this season. The center of the research area showedconsistent low levels of there fatty acid markers all the year around, indicating acomparatively low levels of phytoplankton and lipid nutritional value. Compared toJiaozhou Bay, C. siuicus in the southern Yellow Sea showed comparatively low levelsof PUFA and c}}3 (especially 20:Sc}}3 and 22:6c}}3) and high levels of 20:1 and 22:1，indicating a more herbivorous feeding in this region. The egg production rates offemale C. siuicus showed positively correlations with 16:1c}7,∑16 and 20:Sc}3.Thepresence of these diatom markers suggested the important roles diatom played in thereproduction of C. siuicus.Fatty acid composition of seston in June 2009 displayed a similar spatialdistribution pattern with the cruises conducted in 2006 and 2007. C04 and B18 weredistinguished from other stations by the obvious phytoplankton markers and higherlipid nutritional values. Female and copepodid of C. siuicus showed a typicalherbivorous feeding. But the significantly higher content of 20:1+22:1 in copepodidindicated that copepodid seemed to feed on phytoplankton at a higher level. Besides,copepodid of C. siuicus might feed preferentially on dinoflagellates in view of thefatty acid 18:4c}3.Euphausia pacifica has a higher content of 18:403 than 16:107,indicating a preferential feeding on dinoflagellates. Sagitta was characteristic of highcontent of 22:6c}}3, indicating a higher trophic level in zooplankton. Hyperiidea in thepresent stu勿showed high contents of 16:1c}7, 18:4c}3 and 20:1+22:1，we inferredthat this Amphipoda mainly fed on herbivorous copepod. Stomolophus meleagrisexhibited a distinct feature of feeding on detritus. Generally, C. siuicus, Euphausiapacifica and Hyperiidea might have higher lipid nutritional values for the predators.Principal component analysis was also employed in predators in higher trophic levels.Benthic species such as Phili}te sp., Charybdis japo}tica and Cra}tgo}t affi}tisdistributed away from other species by their obvious fatty acid features of detritus,which might be derived from the direct ingestion of detritus or the feeding on benthic organisms. Pseudosciaeua polyactis, Astrocouger myriaster, Setipiuua taty andCollichthys uiveatus which showed higher contents of phytoplankton grouped together,markers andlipid nutritional values for upper predators could be these speciesshowed higher absorption and transformation rates of dietary fatty acids and fed onherbivorous organisms directly or indirectly.This paper aims at demonstrating the trophic relationships in Yellow Sea in a fattyacid approach. In fact, it is more complex to use this technique in moderate regionsthan in polar areas for the more complex and differing environment. To a betterunderstanding of the trophic linkages in moderate marine environment, we adviseother techniques such as stable isotope analysis also be employed.更多还原