【作者】 林凌；

【导师】 赵云龙；

【作者基本信息】 华东师范大学 ， 动物学， 2015， 博士

【摘要】 近几十年来,全球气温持续升高,在北极地区表现尤为明显,北冰洋也发生了被国际上称之为“尤娜谜”(Unaami)的北极快速变化。北冰洋海冰覆盖面积减少,海冰厚度减少,表层温度升高,盐度减低,中层水变暖,陆地冰川融化,陆源淡水注入增加,表层海水寡营养化。这些都将对北冰洋生态系统产生并正在产生严重影响。微微型浮游生物作为海洋生态系统最重要的组分之一,对环境变化反应灵敏,是良好的环境变化指示生物。并且微微型浮游生物还是北冰洋最主要的初级生产者,在北冰洋能量和物质循环、北冰洋碳固定的过程中发挥重要作用。利用2008年中国第3次北极科学考察和2010年中国第4次北极科学考察的机会,对北冰洋和太平洋亚北极海域环境参数和微微型浮游生物分布进行大范围大尺度调查,了解北冰洋海洋微微型浮游生物群落结构和生物多样性,结合温度盐度营养盐等理化参数分析这种分布特征和海水温度,洋流以及其他因素之间的相关性,有助于了解北冰洋海区海洋生态系统的组成以及分布特征。并对微微型浮游生物分布年际变化进行分析,探讨今后变化趋势,最终为我国进一步探索和利用北冰洋资源打下深厚的基础。对北冰洋和太平洋亚北极海域的环境参数调查结果显示:1、夏季白令海表层30m以浅存在温度高于5°C的表层暖水层,2008年8月向北延伸至楚科奇海陆架65° N,9月到达70° N;2010年8月延伸至69° N,9月则是73° N。2、2008年夏季北白令海20m以浅上层水主要是高温低盐低营养盐的阿拉斯加沿岸水,20m以下则是低温高盐高营养盐的白令海陆架水和盐度更高的阿纳德尔水组成;2010年则阿纳德尔水所占比例相对较少。楚科奇海海域除了太平洋入流以外,北部还受到北冰洋表层混合水影响,形成低盐低营养盐表层水。加拿大海盆100m以浅主要是由盐度较低的北冰洋表层混合水以及包括阿拉斯加沿岸水和白令海陆架水组成,由于波弗特环流、加拿大海盆边界上升流以及太平洋大西洋锋面的影响,随着纬度增加太平洋水也向表层跃迁,越过阿尔法海脊来到马克洛夫海盆后,太平洋水到达表层。3、相比2008年,2010年大部分测区100m以浅的平均温度上升,特别是浅海陆架区。白令海陆架从2.52上升到3.10,白令海峡从2.38到3.01,楚科奇海从0.79到1.44,回程从1.94到2.25,而海盆区则基本保持稳定,温度上升的趋势不明显,有的甚至下降。主要原因是太平洋入流温度增加,太平洋水对北冰洋的影响力增加。4、相比2008年,2010年大部分测区100m以浅平均营养盐浓度下降,并且2010年加拿大海盆100m以浅平均营养盐浓度高于楚科奇海台,预示着楚科奇海陆架区对加拿大海盆的营养盐输送能力下降甚至消失,北冰洋上层水的寡营养化加剧。对北冰洋和太平洋亚北极海域的微微型浮游生物分布调查结果则显示:1、微微型浮游植物是北冰洋和太平洋亚北极海域生态系统最重要的组成部分,白令海盆、楚科奇海和加拿大海盆微微型浮游植物在总叶绿素a浓度中所占平均比例分别是55%、40%和67%。2、聚球藻主要分布在白令海盆,2008年范围是0.01~41.27cells/μ1,平均4.20cells/μ1;2010年则是0.06~22.89cells/μ1,平均4.80cells/μ1。白令海盆聚球藻丰度在1 cells/μ1以上的分布范围相比2008年向北延伸了0.43°;在9月份回程楚科奇海R-2断面,2010年相比2008年发现聚球藻的位置也相比延伸了0.5°。并且2010年在加拿大海盆MS01~MS03以及门捷列夫海脊M03~M05站位发现了聚球藻的新分布区,聚球藻分布的向北延伸是太平洋水对北冰洋影响增加的直接证据3、2008年微微型真核浮游植物在各海区的平均丰度分别是白令海盆、白令海陆架、楚科奇海、楚科奇海台、楚科奇海陆坡、加拿大海盆去程、加拿大海盆回程、门捷列夫海脊、楚科奇海回程的平均丰度分别是7.18、3.69、2.27、2.56、2.01、2.09、1.92、4.08、2.48、2.25cells/μ1;2010 年则分别是 8.81、3.81、2.87、2.72、2.29、3.02、2.29、1.79、2.43、3.04 cells/μ1。都呈现海盆区高于陆架区,亚北极海域高于北极海域的分布特征。并且2010年相比2008年各海区平均丰度上升,与各海区海水温度增加和营养盐浓度降低有关。北冰洋微微型真核浮游植物丰度的增加是对北冰洋表层增温和寡营养化的响应,也是对北极快速变化的响应。4、2008年异养细菌在白令海盆、白令海陆架、楚科奇海、楚科奇海台、楚科奇海陆坡、加拿大海盆去程、加拿大海盆回程、门捷列夫海脊、楚科奇海回程的平均丰度分别是4.80、6.10、5.31、5.46、1.80、2.19、1.55、3.26、2.88、7.83 × 105cells/ml;2010年则分别是 1.63、1.79、2.56、1.45、0.47、0.51、0.69、0.39、1.46 × 105cells/ml。2010年相比2008年各海区异养细菌丰度降低,与营养盐浓度的降低有关。5、微微型浮游植物在白令海盆主要分布在10m~30m之间,在白令海陆架主要分布于上层阿拉斯加沿岸水,楚科奇海加拿大海盆微微型浮游植物极大值也总是与高温低盐低营养盐的阿拉斯加沿岸水相关。6、加拿大海盆微微型浮游植物丰度高于1 cells/μL总是出现在盐度低于311.8 PSU的阿拉斯加沿岸水水层或者北冰洋表层混合水水层,而丰度大于5 cells/μL的峰值区也同样至出现在盐度在30.5左右的阿拉斯加沿岸水水层中。越过阿尔法海脊来到马可洛夫海盆后,太平洋水和大西洋水交汇,太平洋水特别是阿拉斯加沿岸水运动到表层附近,微微型浮游植物极大值层也跃迁至表层。微微型浮游植物极大值层的变化甚至可以作为指示太平洋水和大西洋水锋面的参数。7、北极地区微微型浮游植物与温度有强烈的正相关关系,而与盐度和营养盐浓度之间有极显著的负相关关系。微微型真核浮游植物分布与水团之间有密切关系,但是单纯利用微微型浮游植物丰度很难对水团形成有效的指示作用。利用微微型浮游植物丰度结合盐度,能很好的将北冰洋和太平洋亚北极海域的水团区分开来,微微型真核浮游植物丰度同样能成为北冰洋水团的重要指示参数。更多还原

【Abstract】 At recent decades,Arctic changed quickly as global warming.An Arctic Rapid Change named "Unaami" was happened at Arctic Ocean,including sea ice coverage decreasing,sea ice thickness reduction,sea surface temperature increasing,salinity reduction,intermediate water warming,landing glacier melting,freshwater inflow increasing and surface water being more and more oligotrophic.All of these will play and are playing important role at ecosystem of Arctic Ocean.As one of the most important component of Arctic marine ecosystem,picoplankton is sensitive to environmental variation and could be well indicator of Arctic Ocean changing.Meanwhile,picoplankton also was the main primary producer of Arctic Ocean and played important role in Arctic energy and element cycling and carbon fixing.The 3rd and 4th Chinese National Arctic Research Expedition at 2008 and 2010 provide us an opportunity to the wide range and large-scale investigation toward the environmental situation and picoplankton distribution at Arctic Ocean.It will help us to know the picoplankton community structure and biodiversity of Arctic Ocean.Besides,relationship among distribution characteristic,water temperature,salinity,nutrients and water masses was also analyzed to know the marine ecosystem constitution and picoplankton distribution pattern.Annual variation was also investigated.These will help our country to the development and exploitation of Arctic resources.Results of investigation toward environmental situation at Arctic Ocean and subarctic of Pacific concluded as:1.A warm surface layer with water temperature higher than 5℃ was appeared at Bering Sea,and could reach a latitude of 65° N,70° N,69° N and 73° N at Chukchi Shelf on August,September 2008,August and September 2010,separately.2.Alaskan Coastal Water with high temperature,low salinity and low nutrients concentration constitute the upper 20m layer of Bering Shelf,and when below 20m,they were Bering Shelf Water and Anadyr Water with higher salinity.Anadyr Water contributed fewer percentage of water mass at Bering Shelf on 2010.Besides the Pacific inflow,the north Chukchi Sea also infected by the Arctic Ocean Surface Mixed Water and formed the low salinity and oligotrophic surface water.The upper 100m layer of Canada Basin was mainly constitute by low salinity Arctic Mixed Surface Water and Pacific Water including Alaska Coastal Water and Bering Shelf Water.As latitude increased,Pacific Water transited to the surface with the increasing influence of Beaufort Gyre,Boundary Upwelling of Canada Basin and Pacific/Atlantic Front,and when getting across the Alpha Ridge,Pacific Water reached the surface.3.Compared with 2008,most survey area got increased average water temperature,especially the shallow shelf area.Average water temperature increased from 2.52 to 3.10,2.38 to 3.01,0.79 to 1.44 and 1.94 to 2.25 at Bering Shelf,Bering Strait,Chukchi Sea(outward)and Chukchi Sea(backward),separately.However,average water temperature remained stable,and some survey area even appeared decreased water temperature.The increasing average water temperature was mainly caused by the increasing temperature of Pacific inflow,also means the increasing influenced of Pacific Water to Arctic Ocean.4.Average nutrient concentration decreased at the survey area from 2008 to 2010.Most importantly,average nutrient concentration of Canada Basin was higher than at Chukchi Plateau,means the decreasing and even missing transportation probability of Chukchi Shelf to Canada Basin,and upper layer of Arctic Ocean would be more and more oligotrophic.Results of picoplankton distribution investigation at Arctic Ocean and subarctic of Pacific concluded as:1.Picophytoplankton was the most important component of Arctic and subarctic of Pacific marine ecosystem,it constitute an average of 55%,40%and 67%of total Chl a concentration at Bering Basin,Chukchi Sea and Canada Basin,separately.2.Synechococcus distributed mainly at Bering Basin,with an abundance ranged from 0.01 to 41.27 cells/μl(average of 4.20 cells/μl)and from 0.06 to 22.89 cells/μl(average of 4.80cells/μl)at 2008 and 2010.At Bering Sea,compared with 2008,Synechococcus with abundance larger than 1 cells/μl distributed 0.43° north than at 2010.And when at Chukchi Sea(backward)2010,it was also 0.5° north than at 2008.Besides,new distribution area at section MS at Canada Basin and section M at Mendeleev Ridge were found at 2010,and these confirmed the increasing influence of Pacific Water to Arctic Ocean.3.Average Picoeukaryotes abundance at Bering Basin,Bering Shelf,Chukchi Sea(outward),Chukchi Plateau,Chukchi Slope,Canada Basin(outward),Canada Basin(backward),Mendeleev Ridge and Chukchi Sea(backward)were 7.18,3.69,2.27,2.56,2.01,2.09,1.92,4.08,2.48,2.25 cells/μ1 on 2008 and 8.81,3.81,2.87,2.72,2.29,3.02,2.29,1.79,2.43,3.04 cells/μl on 2010.All reveals the higher abundance at Basin area than Shelf area and higher at Arctic than at subarctic.Average picoeukaryotes abundance of each survey area increased from 2008 to 2010,which was correlated with water temperature increasing and nutrient concentration reduction.It was a responds of picoeukaryotes abundance increasing to Arctic Surface warmer and more oligotrophic,it was also a responds of picoplankton to Arctic Rapid Change.4.Average Heterotrophic Bacteria abundance at Bering Basin,Bering Shelf,Chukchi Sea(outward),Chukchi Plateau,Chukchi Slope,Canada Basin(outward),Canada Basin(backward),Mendeleev Ridge and Chukchi Sea(backward)were4.80,,6.10,5.31,5.46,1.80,2.19,1.55,3.26,2.88,7.83×105cells/ml at 2008 and 1.63,1.79,2.56,1.45,0.47,0.5,0.69,0.39,1.46× 105cells/ml.Average heterotrophic bacteria abundance decreased from 2008 to 2010,it might correlate with the nutrient concentration reduction.5.Picoplankton distributed mainly at 10m-30m of Bering Basin and upper Alaska Coastal Water of Bering Shelf.The peak of picoplankton abundance at Chukchi Sea and Canada Basin were also usually correlated with warmer,lower salinity and lower nutrient concentration Alaska Coastal Water.6.Picoplankton abundance higher than 1 cells/μl was usually appeared at Alaska Coastal Water or Arctic Mixed Surface Water,with salinity lower than 31.8 PSU.And the picoplankton abundance peak(higher than 5cells/μL)was also appeared at Alaska Coastal Water with salinity about 30.5 PSU.When getting across the Alpha Ridge and reaching the Makarov Basin,Pacific Water and Atlantic Water meet here,picoplankton abundance peak transited to the surface in combine with Pacific Water,especially Alaska Coastal Water transition to the surface.We may indicate the Pacific/Atlantic Front via the transition of picoplankton abundance peak.7.There were significant positive correlation of picophytoplankton abundance with water temperature and significant negative correlation with salinity and nutrients.Significant correlation between picophytoplanton abudance and water masse was also found.We cannot identify water mass only via picophytoplanton abundance,however,combine with salinity,we successfully separate water masses.Picoeukaryotes could also be important indicator of Arctic water masses.更多还原