中国科学院海洋研究所机构知识库

深海化能生态系统由于其极其特殊的理化环境特点和生物群落特征，一直是研究的前沿和热点，其中深海热液和冷泉生态系统是最主要的研究部分。热液和冷泉生态系统从发现开始，人们就没有停止对其的探索。研究这样特殊环境下大型生物的营养来源和对重金属的富集作用能够帮助解释其生存策略和适应性，有助于了解深海化能生态系统的物质循环和能量流动过程。本文主要选用稳定同位素法和脂肪酸标记法，并辅以消化道内含物法，利用2015年5-7月和2016年6-9月“科学”号采集的样品，测定并分析了南海Formosa Ridge冷泉区、马努斯盆地热液区和冲绳海槽热液区大型生物的稳定同位素值和脂肪酸含量，对三个区域的大型生物食物来源情况及食性进行分析。选取南海Formosa Ridge冷泉区四种典型的大型生物，首次利用生态学混合模型分析了食物来源比例，定量的描述了各营养源对其食物的贡献，平端深海偏顶蛤（Bathymodiolus platifrons）作为主要的初级消费者，以内共生菌作为主要的营养源，其所提供的营养大约占95 %，水体中的悬浮颗粒物也为其提供营养，仅占5 %，两种甲壳类属于杂食性，以捕食为主，对颗粒物的摄食占了大约30 %，长刺石蟹（Lithodes longispina）主要以捕食冷泉生态系统中的大型生物为食。同时参考大型生物的行为特点和其他海区的研究结果，首次描绘出南海冷泉区的食物网结构图，平端深海偏顶蛤、乳白深海笠贝（Bathyacmae lactea）和螺Provanna glabra处于第二营养级，属于初级消费者，海鳞虫（Branchipolynoe pettibonae）、长角阿尔文虾（Alvinocaris longirostris）、柯氏潜铠虾（Shinkaia crosnieri）以及螺Phymorhynchus buccinoides处于第三营养级，为次级消费者，入侵种长刺石蟹处于最高级，为顶级消费者。选取不同区域的贻贝类，比较稳定同位素和脂肪酸特点，分析环境对贻贝营养源情况的影响。利用南海Formosa Ridge冷泉区平端深海偏顶蛤作为研究对象，对其组织中重金属含量进行了测定，并与不同海区贻贝组织中重金属含量进行了对比，从生物适应性和生物学功能角度解释了其分布模式。

在南海Formosa Ridge冷泉区生态系统中，对平端深海偏顶蛤（B. platifrons）、乳白深海笠贝（B. lactea）、柯氏潜铠虾（S. crosnieri）、长角阿尔文虾（A. longirostris）、海鳞虫（B. pettibonae）、两种腹足类P. buccinoides和P. glabra，以及入侵种长刺石蟹（L. longispina）进行了分析。其碳稳定同位素值均小于-40 ‰，脂肪酸组成以单不饱和脂肪酸为主。在此生态系统中甲烷营养型细菌作为主要的初级生产者而存在。平端深海偏顶蛤作为主要的初级消费者，以内共生菌作为主要的营养源。乳白深海笠贝作为次级消费者，以冷泉生态系统的微生物和有机碎屑作为食物源，其中微生物为主要营养源。腹足类P. glabra作为次级消费者，同样以冷泉生态系统的微生物和有机碎屑作为食物源，但相比于乳白深海笠贝，其营养来源更多的来自于有机碎屑。腹足类P. buccinoides作为次级消费者，主要以生物尸体和上层沉降有机碎屑为主要食物源，相比于P. glabra，其更多的营养源来自于光合作用系统。海鳞虫作为次级消费者，以贻贝和其它高营养级生物尸骸为主要食物源。长角阿尔文虾作为次级消费者，为杂食性，以低营养级的生物体和颗粒有机物为主要食物源。柯氏潜铠虾作为次级消费者，为杂食性，主要以体表微生物、低营养级的生物体和颗粒有机物为主要食物源。入侵种长刺石蟹作为顶级捕食者，主要以冷泉生物为主要食物源，并且也会摄食有机颗粒物。

在马努斯盆地热液区生态系统中，对潜铠虾Munidopsis lauensis、虾Chorocaris vandoverae、贻贝Bathymodiolus manusensis、管状蠕虫Arcovestia ivanovi以及两种腹足类Ifremeria nautislei和Provanna nassariaeformis进行了分析。其碳稳定同位素值均大于-35 ‰，脂肪酸组成除P. nassariaeformis外均以单不饱和脂肪酸为主。硫氧化型细菌作为主要的初级生产者供给整个生态系统。贻贝B. manusensis作为主要的初级消费者，其营养源主要来自其共生细菌，并且其共生细菌利用卡尔文循环（Calvin-Benson-Bassham, CBB）进行固碳作用，属于Rubisco Ⅰ型，其体内的共生多毛类营养源主要依赖于其宿主。管状蠕虫A. ivanovi同样以内共生的化能自养细菌为主要营养源，但其类型与贻贝中共生物微生物不同。两种腹足类I. nautislei和P. nassariaeformis均以碎屑和动物尸骸为主要营养源，主要营养源来自于热液生态系统本身，但二者相比，后者来源于上层光合作用系统的营养源较多。潜铠虾M. lauensis和虾C. vandoverae为杂食者，主要以低营养级的生物体和颗粒有机物为主要食物源。

在冲绳海槽热液区生态系统中，对长角阿尔文虾（A. longirostris）、光足新海虾（Shinkaicaris leurokolos）、海鳞虫（B. pettibonae）以及拟阿尔文虫（Paralvinella hessler）进行了分析。其碳稳定同位素值均大于-35 ‰，脂肪酸组成除Dive #102区域的海鳞虫外均以单不饱和脂肪酸为主。甲烷营养型和硫氧化型细菌同时作为主要的初级生产者供给整个生态系统。平端深海偏顶蛤作为主要的初级消费者，其营养源主要来自其共生细菌，同时也存在滤食作用来源，在Dive #102区域的贻贝中表现较明显。海鳞虫共生于贻贝的外套膜腔内，营养主要来源于其宿主，同时也摄食微生物和生物尸骸和有机碎屑。拟阿尔文虫以共生的化能自养细菌为主要营养源，但其类型与贻贝不同，主要为硫氧化型细菌。两种长角阿尔文虾和光足新海虾都以化能自养细菌和低营养级生物体为主要食物源，但是两种虾所利用的化能自养细菌类型不同，前者所利用的化能细菌主要利用CBB循环固碳，而后者所利用的化能细菌主要利用还原性三羧酸循环（reductive tricarboxylic acid cycle, rTCA）来固碳。

对深海化能生态系统中的贻贝类与近海远东偏顶蛤（Modiolus kurilensis）进行对比分析。远东偏顶蛤表现出明显的差别，碳同位素值大于-20 ‰，脂肪酸组成以多不饱和脂肪酸为主，且富含C20:5ω3和C22:6ω3系列脂肪酸。其主要通过滤食作用获取食物，营养源来自于光合作用系统，主要为藻类，而深海冷泉和热液区贻贝类的营养来源主要来自于化能自养细菌。

对南海Formosa Ridge冷泉区平端深海偏顶蛤的鳃、外套膜和壳中的20种金属元素含量进行了测定。结果显示多数金属元素在鳃中都显著富集，这可能与食物的吸收和共生菌的存在有关。在壳和外套膜中，Mn的含量都特别高，这可能与对碳酸盐结构中Ca的替代作用有关。在鳃和外套膜中发现了Ca、Sr和Mg之间存在正相关关系，这与以往在热液和近岸贻贝中的研究结果相符。相比于其他深海环境和近岸环境中的贻贝，金属的富集展现出地域的差异但也存在着相似的富集和吸收模式，这意味着对必需元素的需求在不同区域贻贝中存在着相似性。Mn和Ag含有较高的生物浓度因子（BCF），这说明了它们与生物特别的适应和生命循环过程中特殊功能和调节机制有关。

The deep-sea chemotrophic ecosystem has always been the forefront and hotspot in the research because of the special characteristics of physical and chemical environment and communities. The deep-sea hydrothermal and cold seep ecosystems are most important parts. Since hydrothermal and cold seep ecosystems discovered, people have been exploring. Studying nutritional sources and the heavy-metal enrichment of macrofauna in the special environment could help to explain the survival strategies and adaptability and understand the process of material circulation and energy flow. The stable isotope approach and the fatty acid biomarkers detection were used as principal methods, and the stomach content analysis was used as the complement. We used samples collected in May-July 2015 and June-September 2016 by the R.V. Kexue to measure and analyze the values and compositions of the stable isotope and fatty acid in the macrofauna from the Formosa Ridge cold seep in the South China Sea, the Manus basin hydrothermal vents and the Okinawa Trough hydrothermal fields. We analyzed nutritional sources and feeding habits of the macrofauna. Four major animals from the cold seep in the South China Sea were chosen to analyze food source ratios using a mixing model for the first time. We quantitied the contribution of each source for food. B. platifrons reilid on endosymbiotic bacteria mostly, which accounted for 95 %. While particulate organic matter took up 5 %. Two crustaceans were omnivorous and relied on predation. While particulate organic matter took up 30 %. Lithodes longispina preyed on animals in the cold seep ecosystem mostly. We took the results from other areas and behavior characteristics of animals into account and then described the food web model for the first time. B. platifrons, Bathyacmae lactea and Provanna glabra were at the second level, which were primary consumers. Branchipolynoe pettibonae, Alvinocaris longirostris, Shinkaia crosnieri and Phymorhynchus buccinoides were at the third level, which were secondary consumers. The invader L. longispina was at the highest level, which was the top predator. The characteristics of the stable isotope and fatty acid in mussels from different sites were compared to analyze the effect of different sites on nutritional sources. We used B. platifrons from the Formosa Ridge cold seep in the South China Sea as the research object to measure the component of heavy metals and explain these distribution patterns from the perspective of adaptability and biological function.

We analyzed the data of B. platifrons, B. lactea, S. crosnieri, A. longirostris, B. pettibonae, Phymorhynchus buccinoides, P. glabra and the invader L. longispina from the ecosystem of the Formosa Ridge cold seep in the South China Sea. The δ¹³C values of all specimens were below -40 ‰, and the compositions of fatty acids were dominated by monounsaturated fatty acids. Methane-based bacteria is the major primary producer in this ecosystem. B. platifrons was the major primary consumer relied on endosymbiotic bacteria. B. lactea was a secondary consumer relying on microorganism and organic detritus in this ecosystem. Among food sources, microorganism was the main source. The gastropod P. glabra was a secondary consumer relying on microorganism and organic detritus. However, compared with B. lactea, the food source was more from organic detritus. The other gastropod P. buccinoides was a secondary consumer relying on cadavers and the upper organic detritus. Compared with the little gastropod P. glabra, the food sources were more from photosynthesis ecosystem. B. pettibonae was a secondary consumer relying on mussels and carcass from highly trophic animals. A. longirostris was a secondary consumer as an omnivorous animal, relying on particle organic matter and low trophic level organisms. S. crosnieri was a secondary consumer as an omnivorous animal, relying on epibiotic microorganisms, particle organic matter and low trophic level organisms. The invader L. longispina was the top predator, relying on animals from the cold seep majorly and little particle organic matter.

In the Manus basin hydrothermal vents ecosystems, we analyzed the data of Munidopsis lauensis, Chorocaris vandoverae, Bathymodiolus manusensis, Arcovestia ivanovi, Ifremeria nautislei and Provanna nassariaeformis. The δ¹³C values of all specimens were above -35 ‰, and the compositions of fatty acids were dominated by monounsaturated fatty acids except of P. nassariaeformis. Sulfur-based bacteria is the major primary producer in this ecosystem. B. manusensis was the major primary consumer relied on endosymbiotic bacteria. The endosymbionts used the CBB cycle and with Rubisco form Ⅰ as the CO2-fixing enzyme. Commensal polychaetes mostly obtained their nutrition from their hosts. Vestimentiferans obtained food from symbiotic bacteria, which belonged to different types from the bacteria in mussels. I. nautislei and P. nassariaeformis both relied on organic detritus and cadavers in the hydrothermal ecosystem. The latter one relied on more sources from photosynthesis ecosystem. M. lauensis and C. vandoverae as omnivorous animal relied on particle organic matter and low trophic level organisms.

In the ecosystems of the Okinawa Trough hydrothermal fields, we analyzed the data of A. longirostris, Shinkaicaris leurokolos, B. pettibonae and Paralvinella hessleri. The δ¹³C values of all specimens were above -35 ‰, and the compositions of fatty acids were dominated by monounsaturated fatty acids except of B. pettibonae from Dive #102. Methane-based and sulfur-based bacteria are both major primary producer in this ecosystem. B. platifrons was the major primary consumer relied on endosymbiotic bacteria. Moreover, it had sources from the filtration, especially in the Dive #102 field. B. pettibonae survived in the cavity of mantles, relying on its host mostly, microorganisms, cadavers and organic detritus were all nutritional sources. P. hessleri obtained food from symbiotic bacteria, which belonged to different types from the bacteria in mussels. The symbionts were sulfur-based bacteria primarily. A. longirostris and S. leurokolos were both relied on chemoautotrophic bacteria and low trophic level organisms. However, the bacteria they used were different. The former one used the bacteria which fixed carbon with the CBB cycle, while the latter one used the bacteria which fixed carbon with the rTCA cycle.

We compared the data of mussels from deep-sea chemotrophic ecosystems and Modiolus kurilensis from coastal waters. M. kurilensis was significantly different from mussels from deep-sea chemotrophic ecosystems in several aspects. The δ¹³C values of M. kurilensis were above -20 ‰, and the compositions of fatty acids were dominated by polyunsaturated fatty acids. The components of fatty acid were rich in the types of C20:5ω3 and C22:6ω3. We can inferred that they obtained food by filter-feeding, and the food sources were from photosynthesis ecosystem, mainly from algae. However, mussels from deep-sea chemotrophic ecosystems relied on chemoautotrophic bacteria mainly.

We quantified the presence of twenty elements in gills, mantles and shells of Bathymodiolus platifrons from the Fomosa Ridge cold seep in the South China Sea. We found that most elements were significantly enriched in the gills, which could be related to food uptake and the existence of endosymbionts. In shells and mantles, Mn was particularly rich, possibly due to its replacement of Ca in the carbonate structure. A significant positive correlation among Ca, Sr, and Mg was found in both gills and mantles, consistent with relationships observed in vent and littoral mussel species. Compared with other deep-sea environments and coastal areas, metal accumulation showed local variability but similar overall patterns of uptake and accumulation, indicating that essential elemental requirements in different mussel species may be similar across taxa. The high bioconcentration factor (BCF) values of Mn and Ag suggest that their particular functions and regulation mechanisms are related to specific adaptations and life cycle processes.