2013年8月和11月辽东湾近岸海域浮游植物群落结构

在辽东湾水体中设置8个采样点,于2013年8月11日和11月26日,在8个采样点采集浮游植物样品,对浮游植物群落结构进行调查;利用多维尺度分析方法,研究两次采样和各采样点之间浮游植物的密度和群落关系。本次调查共发现浮游植物65种,其中8月记录53种,11月记录43种;浮游植物主要由硅藻和甲藻组成,还有少量的绿藻、蓝藻、裸藻和金藻,优势种为硅藻;8月,浮游植物的优势种主要为丹麦细柱藻(Leptocylindrus danicus)、尖刺拟菱形藻(Pseudo-nitzschia pungens)、星脐圆筛藻(Coscinodiscus asteromphalus);8月,浮游植物的优势种主要为星脐圆筛藻、具槽帕拉藻(Paralia sulcata)和中心圆筛藻(Coscinodiscus centralis),8月与11月浮游植物的物种组成和优势种组成存在差异,说明浮游植物群落结构随季节发生变化。8月,浮游植物细胞密度为6.34×104~286.43×104cells/L,平均值为104.52×104cells/L;11月,浮游植物细胞密度为2.31×104~16.4×104cells/L,平均值为8.28×104cells/L。8月,各采样点浮游植物Shannon-Wiener多样性指数为3.25~4.62,平均值为3.94;11月,各采样点浮游植物Shannon-Wiener多样性指数为2.25~3.39,平均值为2.80,表明8月调查海域的生境质量好于11月。对浮游植物群落结构的多维分析结果显示,辽东湾沿岸与近岸浮游植物群落结构差异显著。     

连云港市徐圩新区张圩湖和云湖浮游动物和浮游植物群落组成研究

于2021年9月,在连云港徐圩新区的张圩湖和云湖,采集表层水体样品,鉴定浮游动物和浮游植物物种,分析浮游动物群落和浮游植物群落的物种组成和多样性,测定水样的理化指标,探讨浮游动物群落和浮游植物群落组成与环境因素的关系。研究结果表明,在张圩湖和云湖表层水体中,共鉴定出浮游植物6门64种,云湖中的浮游植物物种数量较多,两座湖泊的相同优势物种为极小集胞藻(Synechocystis minuscula);鉴定出浮游动物3门20种,云湖中的浮游动物物种数量较多,两座湖泊的相同优势物种为无节幼体(nauplius)和桡足幼体(copepodid);张圩湖表层水体中浮游动物群落和浮游植物群落的物种多样性水平为贫乏—一般,水体污染程度为中重度,云湖表层水体中浮游动物群落和浮游植物群落的物种多样性水平为一般—较丰富,水体污染程度为轻中度,与张圩湖相比,实施生态工程10 a的云湖中的浮游动植物物种数量、生物多样性水平都显著提升;影响两座湖泊浮游动物群落和浮游植物群落多样性的主要环境因素为水体的化学需氧量和氨氮含量(两座湖泊)、总氮和硝氮含量(云湖)以及水体盐度、电导率和水深(张圩湖)。     

辽东湾北部浅海中浮游植物群落的特征及其与水环境因素的关系

2018年4月、6月、9月和11月,在辽东湾北部浅海中的6个采样点,采集了浮游植物、水和沉积物样品,测定了水环境指标,研究了浮游植物的群落结构及其与水环境因素的关系。研究结果表明,在6个采样点,共记录2门26属50种浮游植物;浮游植物群落的优势物种为夜光藻(Noctiluca scintillans)和中肋骨条藻(Skeletonema costatum)等共22种;9月采样日的浮游植物丰度相对最大;4月、6月、9月和11月采样日,浮游植物群落的Margalef物种丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数值分别变化在1.55～3.93、1.53～3.85和0.42～0.95之间;浮游植物群落优势物种的季节更替率、物种更替指数和迁移指数值分别变化在60.0%～88.2%、34.48%～67.44%和-17.24%～11.63%之间;水温、水体pH、沉积物pH、水体的盐度以及水体中的叶绿素a、化学需氧量、溶解无机氮、溶解氧、硝酸盐氮和氨氮含量与浮游植物群落结构相关,优势物种的丰度与水环境因素关系密切。     

射阳湖浮游植物群落结构和水体污染状况

于2018年9月至2019年8月的每月中下旬,对射阳湖水体中的浮游植物群落进行了调查,重点分析了浮游植物群落的结构特征及其与环境因素的关系,并对射阳湖水体的污染状况进行了评价。研究结果表明,在射阳湖的浮游植物样品中,共鉴定出浮游植物8门157种,其中,绿藻门物种数量(61种)最多,其次为硅藻门(37种)、蓝藻门(29种)和裸藻门(18种)的物种数量,金藻门(5种)、隐藻门(4种)、甲藻门(2种)和黄藻门(1种)的物种数量较少;浮游植物群落的优势物种为小球藻(Chlorella vulgaris)、月牙藻(Selenastrum bibraianum)和湖泊伪鱼腥藻(Pseudanabaena limnetica);浮游植物丰度为0.36×10⁶～10.25×10⁶cell/L,平均值为3.27×10⁶cell/L;射阳湖的水体处于贫—中营养状态;夏季,浮游植物丰度最大,冬季的最小;浮游植物群落的Shannon-Wiener多样性指数和Pielou均匀度指数的平均值分别为2.72和0.87,射阳湖的水体为轻度—中度污染水体...     

2011年夏季南大洋普里兹湾颗粒态生物硅的分布与变化特征

利用中国第27次南极科学考察期间获得的颗粒物样品,对南大洋普里兹湾海域水体中颗粒态生物硅的含量及分布特征进行了初步研究,分析了该海域颗粒态生物硅与营养盐、浮游植物以及颗粒有机碳之间的关系,同时结合历史数据对比了颗粒态生物硅的年际变化情况。研究结果显示：在2011年夏季普里兹湾表层水体中颗粒态生物硅含量在0.76-19.72μmol/ dm3之间变化,平均为6.06±4.55μmol/ dm3。在表层水体中的分布趋势是67°S以南的湾内区域颗粒态生物硅含量明显高于67°S以北的湾外区域,最大值出现在普里兹湾陆架区。在垂向分布上,P3断面水体中颗粒态生物硅含量随深度增加而减少。根据不同年份即24,25,26,27次南极科学考察期间获取的数据对比分析显示,颗粒态生物硅含量虽存在一定的年际差异,但是在普里兹湾的分布趋势基本一致。颗粒态生物硅含量的变化特征与硅酸盐相反与叶绿素a、颗粒有机碳相似。     

北冰洋中心区表层海水营养盐水平及浮游植物群落对快速融冰的响应

本文依托2010夏季中国第四次北极科学考察,通过对高纬度极地冰下水和冰芯的营养盐的连续观测及表层水颗粒物的藻类色素分析,获取了夏季快速融冰下冰水界面营养盐和光合色素的分布信息。结果表明调查期间表层水磷酸盐和硅酸盐相对于无机氮更丰富（依据Redfield比值）,表现为显著的氮限制。而冰芯无机氮浓度相对更高,融冰释放对水体无机氮有一定的补充。色素分析显示岩藻黄素（Fuco）和叶绿素a（Chl a）是水体颗粒物的主要光合色素。在8/15至8/18期间,叶绿素c（Chl c）、硅藻黄素（Diato）、硅甲藻黄素（Diadino）和岩藻黄素（Fuco）分别达到6,22,73和922μg/m3,体现了硅藻在群落中的优势地位。岩藻黄素（Fuco）的浓度在融冰快速期间有巨大的提升,主要来源于冰芯底部释放的衰老的冰生硅藻和浮游硅藻的生长。此外,青绿黄素（Prasino）和叶黄素（Lut）与岩藻黄素（Fuco）分布模式有明显的差异,暗示青绿藻和绿藻与硅藻对海冰融化的不同响应。     

南极普里兹湾沉积生物标志物记录及浮游植物群落结构变化

本文利用浮游植物标志物（菜子甾醇、甲藻甾醇和长链烯酮）作为重建单种浮游植物（硅藻、甲藻和颗石藻）的指标,对普里兹湾浮游植物群落结构的变化进行研究。结果表明研究海域表层沉积物和III-12柱样沉积物中的生物标志物记录具有明显的空间和时间变化特征。用生物标志物重建的浮游植物总量（菜子甾醇+甲藻甾醇+长链烯酮）变化范围在391.0~1470.6ng/g之间,在过去的大约100年时间里海洋初级生产力呈上升趋势,但近10年略有下降,这种分布趋势与区域气候变化密切相关。普里兹湾及其邻近海域表层沉积物中浮游植物标志物的总含量变化范围为215.2~1249.3 ng/g,重建的浮游植物生产量呈现湾内高、湾外低（陆坡、深海区最低）的特征,并与2005年现场调查资料表层海水叶绿素a、有机碳和生物硅含量分布趋势相符,最大值均出现在普里兹湾中心区域,这意味着底部被埋藏的浮游植物标志物总含量和硅藻植物群落有很高的一致性,反映出海洋底部对上层海洋过程的一致响应。     

广东孔江国家湿地公园水体中的浮游植物群落结构特征

于2019年7月22日、10月4日、12月20日和2020年3月21日,在广东孔江国家湿地公园水体中,采集浮游植物样品,研究了浮游植物群落的结构及其变化特征,并根据浮游植物群落结构、Shannon-Wiener多样性指数和Pielou均匀度指数,对广东孔江国家湿地公园中水体的污染状况和水体营养型进行了评价。研究结果表明,在广东孔江国家湿地公园水体中共检测到浮游植物107种(含变种),隶属于8门69属,其中绿藻门、硅藻门和蓝藻门的物种数占优势,分别占总物种数的42.06%、29.91%和10.28%;水体中的浮游植物丰度为3.84×10~5～196.99×10~5 ind./L,平均丰度为45.39×10~5 ind./L;2019年10月4日水体中的浮游植物丰度最大,其次为2019年7月22日,2019年12月20日和2020年3月21日浮游植物丰度较小;入库口处水体中的浮游植物丰度最大,平均丰度为72.21×10~5 ind./L,而入库溪流处丰度最低;不同季节水体中浮游植物群落的优势种差异明显,2019年7月22日和10月4日以绿藻门的六臂角星鼓藻(Staurastrum senarium)和珍珠角星鼓藻(Staurastrum margaritaceum)以及蓝藻门的巨颤藻(Oscillatoria princeps)和拟柱孢藻(Cylindrospermopsis rackiborskii)为优势种,2019年12月20日和2020年3月21日以隐藻门的卵形隐藻(Cryptomons ovata)和金藻门的圆筒形锥囊藻(Dinobryon cylindricum)为优势种;浮游植物群落的Shannon-Wiener多样性指数和Pielou均匀度指数都在2020年3月21日最大,2019年10月4日最小;广东孔江国家湿地公园中水体的水质总体上为中污染,水体营养型为贫—中营养型。     

新疆阿克达拉水库浮游植物群落生态特征

为了解其水生生物生态现状,于2008年7月(平水期)、10月(枯水期)和次年5月(丰水期)对阿克达拉水库内浮游植物群落生态特征进行了研究.共采集到浮游植物8门101种,其中硅藻40种、绿藻38种、蓝藻7种、裸藻6种、黄藻4种、金藻3种、隐藻2种和甲藻1种,绿藻与硅藻在种类组成上具有显著优势.不同时期浮游植物种类组成呈现...     

2011夏季南极普里兹湾营养盐与浮游植物生物量的分布

利用2011南极夏季在普里兹湾获取的海水样,检测了Chla、磷酸盐、硅酸盐、硝酸盐和铵盐的含量。结果表明,普里兹湾表层海水中Chla的含量普遍具有冰架边缘>陆架区>陆坡及深海区的分布特征,海冰的消融及水体的稳定性是影响表层海水Chla分布的主要原因。Chla含量的垂直分布与光照条件相关,具有上层水体含量高,随着深度逐渐降低的分布特征。磷酸盐、硅酸盐和硝酸盐的水平及垂直分布特征都与Chla的分布格局相反。表层海水中铵盐的分布特征与磷酸盐等主要营养盐的分布格局相反,冰架边缘、陆架区铵盐的垂直分布特征与陆坡及深海区不同,在冰架边缘和陆架区有机质降解过程主导着水柱中铵盐的浓度,而浮游植物吸收作用与有机质降解过程之间的平衡控制着陆坡及深海区铵盐的垂直分布。根据Chla与营养盐的浓度及分布特征,结合温度、盐度、溶解氧等水文要素,分析探讨了Chla深层最大值现象（DCM）的成因及67.5°S以南表层海水中铵盐对硝酸盐吸收的抑制作用。     

南极半岛邻近海域夏季POC分布特征及其影响因素

海水中的颗粒有机碳(POC)与生物的生命过程、初级生产力关系密切,是海洋食物链中重要的物质基础和能量来源,因此POC的分布特征可以有效反映其生物地球化学环境。利用中国第33次南极考察期间(2016年12月至2017年1月)在南极半岛邻近海域采集的海水颗粒物样品,研究POC的空间分布特征及其影响因素。结果表明,斯科舍海0—200 m的POC浓度范围为7.44—193.52μg·L~(-1),平均浓度为(48.84±35.09)μg·L~(-1);南斯科舍海岭0—200 m的POC浓度范围为9.13—62.17μg·L~(-1),平均浓度为(29.76±14.12)μg·L~(-1);鲍威尔海盆0—200 m的POC浓度范围为5.87—270.72μg·L~(-1),平均浓度为(48.57±38.92)μg·L~(-1)。表层POC高值出现在斯科舍海区和鲍威尔海盆区,而低值出现在海岭区,与叶绿素a(Chla)的变化趋势一致,与营养盐的变化趋势相反。垂向分布上,各个区域POC平均浓度随深度的增加而减少,鲍威尔海盆和斯科舍海POC最高值都出现在25 m层。分析结果表明光合浮游植物是研究海域POC的主要来源, POC的主要影响因素为温度、水团混合以及海冰环境。斯科舍海与鲍威尔海盆整体非生命POC占比高,可能是由于高磷虾生物量、海冰碎屑以及陆源输入的干扰;南斯科舍海岭整体非生命POC占比低。     

Dynamics of plankton growth in the Barents Sea: model studies

1-D and 3-D models of plankton production in the Barents Sea are described and a few simulations presented. The 1-D model has two compartments for phytoplankton (diatoms and P. pouchelii) , three for limiting nutrients (nitrate, ammonia and silicic acid), and one compartment called "sinking phytoplankton". This model is coupled to a submodel of the important herbivores in the area and calculates the vertical distribution in a water column. Simulations with the 3-D model indicate a total annual primary production of 90-120g C m⁻² yr⁻¹ in Atlantic Water and 20-50g C m⁻² yr⁻¹ in Arctic Water, depending on the persistence of the ice cover during the summer.
The 3-D model takes current velocities, vertical mixing, ice cover, and temperature from a 3-D hydrodynamical model. Input data are atmospheric wind, solar radiation, and sensible as well as latent heat flux for the year 1983. The model produces a dynamic picture of the spatial distribution of phytoplankton throughout the spring and summer. Integrated primary production from March to July indicates that the most productive area is Spitsbcrgenbanken and the western entrance to the Barents Sea. i.e. on the northern slope of Tromsøflaket.     

Interannual variability in water masses in the Greenland Sea and adjacent areas

Oceanographic data covering the period 1950–1998 are used to determine interannual variations in the convection intensity and water mass structure in the Greenland Sea and adjacent areas. Extremely cold winters throughout 1965–1970 assisted intensification of the water vertical exchange in the Greenland and Norwegian seas. As a result, cold and fresh Greenland Sea Deep Water (GSDW) production was extremely high in the central Greenland Sea while in the southern Norwegian Sea warm and salty water spread downwards. The recent rapid warming in the Greenland Sea Gyre interior from 1980 originates, we argue, from an increase in the Atlantic Water (AW) temperature due to the advection of warm waters into the region with the Return Atlantic Current. The negative water temperature and salinity trends in the upper 300 m layer of the Atlantic Water in the Norwegian Sea prevailed during 1950–1990, whereas during 1980–1990 the water temperature trends are indicative of warming of that layer. Observation series obtained onboard the Ocean Weather Ship Mike confirmed the existence of layers with advectiondriven high oxygen concentrations in intermediate and deep layers. The depth of oxygen maxima and the values of oceanographic parameters at this horizon can be regarded as indicators of the convection intensity in the Arctic domain. A simultaneous rise in NAO index and GSDW temperature points to a link between atmospheric and thermohaline circulation. Weakening in water exchange with the North Atlantic could be the reason for the Polar Water recirculation increase within the Nordic seas.     

白令海和楚科奇海表层沉积硅藻分布特征

对我国第二次和第三次北极科学考察在白令海和楚科奇海获取的部分表层沉积物样品进行了详细的硅藻分析,旨在了解白令海和楚科奇海表层沉积硅藻的主要分布情况。研究发现海冰对北极硅藻有着显著的影响,在最小冰边缘线以北海域,由于常年被海冰覆盖,表层沉积物中的硅藻数量极少甚至缺失,而在此范围以南海域,硅藻含量则甚为丰富。白令海和楚科奇海表层沉积物中最主要的硅藻种类及组合有：角毛藻休眠孢子(Chaetoceros resting spores),海冰硅藻组合(以Fragilariopsis oceanica和Fragilariopsis cylindrus为代表),极地硅藻组合(优势种有Bacterosira bathyomphla,Thalassiosira antarctic v. borealis及其休眠孢子),沿岸底栖硅藻组合(主要有Paralia sulcata和Delpheneis surirella),诺氏海链藻(Thalassiosira nordenskioeldii)和塞米新细齿藻(Neodenticula seminae)等。上述硅藻种类及组合具有显著的空间分布差异性,并与现代海洋环境因素密切相关,因此对于白令海和楚科奇海古海洋环境研究具有重要意义。     

Functional attributes of epilithic diatoms for palaeoenvironmental interpretations in South-West Greenland lakes

Benthic diatoms are commonly used for palaeoenvironmental reconstruction in Arctic regions, but interpretation of their ecology remains challenging. We studied epilithic diatom assemblages from the shallow margins of 19 lakes from three areas (coast-inland-ice sheet margin) along a climate gradient in Kangerlussuaq, West Greenland during two periods; shortly after ice-off (spring) and in the middle of the growth season (summer). We aimed to understand the distribution of Arctic epilithic diatoms in relation to water chemistry gradients during the two seasons, to investigate their incorporation into lake sediments and to assess their applicability as palaeoenvironmental indicators. Diatoms were correlated with nutrients in the spring and alkalinity/major ions in the summer, when nutrients were depleted; approximately half of the variance explained was independent of spatial factors. When categorised by functional attributes, diatom seasonal succession differed among regions with the most obvious changes in inland lakes where summer temperatures are warmer, organic nutrient processing is prevalent and silicate is limiting. These conditions led to small, motile and adnate diatoms being abundant in inland lakes during the summer (Nitzschia spp., Encyonopsis microcephala), as these functional attributes are suited to living within complex mats of non-siliceous microbial biofilms. Seasonal succession in silica-rich lakes at the coast was less pronounced and assemblages included Tabellaria flocculosa (indicating more acidic conditions) and Hannaea arcus (indicating input from inflowing rivers). The nitrogen-fixing diatom Epithemia sorex increased from the coast to the ice sheet, negatively correlating with a gradient of reactive nitrogen. The presence of this diatom in Holocene sediment records alongside cyanobacterial carotenoids during arid periods of low nitrogen delivery, suggests that it is a useful indicator of nitrogen limitation. Nitzschia species appear to be associated with high concentrations of organic carbon and heterotrophy, but their poor representation in West Greenland lake sediments due to taphonomic processes limits their palaeoenvironmental application in this region. Proportions of epilithic taxa in lake sediment records of coastal lakes increased during some wetter periods of the Holocene, suggesting that snowpack-derived nutrient delivery may offer diatom taxa living at lake margins a competitive advantage over planktonic diatoms during the “moating” ice melt period. Thus, further research investigating linkages between epilithic diatoms, snowpack and nutrient delivery in seasonally frozen lakes is recommended as these taxa live on the ‘front-line’ during the spring and may be especially sensitive to changes in snowmelt conditions.     

Contribution of waters of Atlantic and Pacific origin in the Northeast Water Polynya

Measurements of nitrate and phosphate taken in the Northeast Water Polynya (NEWP) during the summer of 1993 have been used to identify the contribution of waters of Atlantic and Pacific origin in the polynya. Since waters from the northern Pacific exhibit a deficit in nitrate relative to phosphate due to denitrification in low oxygen waters, the relationship between nitrate and phosphate can be used to distinguish between oceanic waters of Pacific and Atlantic origin. The Pacific Water enters the Arctic Ocean through Bering Strait and flows along the northern coasts of Alaska and Canada. Some of this water exits through Fram Strait and may therefore enter the polynya which is situated above the continental shelf off the north-eastern coast of Greenland. Compared to data from the Greenland Sea, which only show a N–P relationship of typical Atlantic Water, the data from the Northeast Water Polynya show that the upper waters of the polynya bear a clear signal of waters of Pacific origin. In the surface mixed layer an average of about 90% is found to have Pacific N–P characteristics. Below the surface mixed layer the amount of Pacific derived water decreases through the halocline and from about 150 m to the bottom only typical Atlantic Water is found.     

Upper layer circulation of the Nordic seas as inferred from the spatial distribution of heat and freshwater content and potential energy

The spatial distribution of heat and freshwater content and potential energy of a several hundred metre thick surface layer are computed for the Nordic seas and adjacent parts of the northern North Atlantic and the Arctic Ocean using a total of almost 100 000 hydrographic stations. The fields clearly show the major features of the area's circulation, with warm salty water in the eastern part and fresher, colder water in the western part. Comparisons with published estimates show that the potential energy field, representing the baroclinic part of the flow, accounts for about 30 % of the total flow but roughly 100 % of the flow of Polar Water in the northern part of the East Greenland Current, about 50 % of the total flow in the Norwegian Atlantic Current, and just a small fraction of the flow in the eastern part of Fram Strait. This suggests that the barotropic circulation is quite important in many parts of the Nordic seas. The barotropic circulation is also clearly seen by its effects on the integrated fields with isolines following deep bathymetric contours. We speculate that the barotropic circulation in combination with topographic obstacles, like the Greenland–Scotland Ridge and the ridge system in the Jan Mayen area, may have large impact on the spreading of freshwater and heat in the Nordic seas.     

楚科奇海和白令海浮游植物的种类组成与分布

根据 1 999年 7月至 8月我国首次北极科学考察期间“雪龙”号考察船在楚科奇海 ( 66°0 .3′N75°1 8.6′N ,1 5 3°36.5′W 1 74°5 9.5′W )和白令海 ( 5 5°5 9.8′N66°0 .3′N ,1 73°2 1 .1′E1 75°5 3.9′W)采集的 5 1份网采样品和 2 4份水采样品 ,鉴定浮游植物 3个门类 38属 1 2 1种 (含变种和变型 ) ,都是真核藻类。其中楚科奇海有 33属 1 0 3种 ,白令海有 2 5属 71种 ,两海区共有种 49种。这些种类可分为 4个生态类群 :( 1 )北极类群 ;( 2 )北极、亚北极北方类群 ;( 3)北方温带类群 ;( 4 )世界性广温类群等。主要优势种有楚科奇海的格鲁菱形藻 (Nitzschiagrunowii)、诺登海链藻(Thalassiosiranordenskioldi)和聚生角毛藻 (Chaetocerossocialis)等和白令海的西氏细齿状藻(Denticulaseminae)、柔弱菱形藻 (Nitzschiadilicatissima)、成列菱形藻 (N .seriata)和长海毛藻(Thalassiothrixlongissima)等。楚克奇海浮游植物的平均丰度 ( 8.32× 1 0 7个 /m3)远高于白令海( 1 .5 8× 1 0 6个 /m3)。文中还讨论了调查区浮游植物的分布特点及其与环境的关系。     

Phytoplankton dynamics in the Barents Sea estimated from chlorophyll budget models

Pigment budgets use chlorophyll a and phaeopigment standing stock in combination with their photo-oxidation and sedimentation rates in the euphotic zone to estimate phytoplankton growth and grazing by micro- and macrozooplankton. Using this approach, average phytoplankton growth in the euphotic zone of the Barents Sea was estimated at 0.17 and 0.14 d⁻¹ during spring of 1987 and 0.018 and 0.036 d⁻¹ during late- and postbloom conditions in summer of 1988. Spring growth was 65% lower than the estimates from radiocarbon incorporation, supporting a 33% pigment loss during grazing. Macrozooplankton grazing and cell sinking were the main loss terms for phytoplankton during spring while microzooplankton grazing was dominant in summer.
In contrast to tropical and temperate waters, Arctic waters are characterized by a high phaeopigment: chlorophyll a ratio in the seston. Photooxidation rates of phaeopigments at in situ temperatures (0 ± 1°C) are lower than in temperate waters and vary by a factor of 2 for individual forms (0.009 to 0.018 m⁻²mol⁻¹). The phaeopigment fraction in both the suspended and sedimenting material was composed of seven main compounds that were isolated using high-performance liquid chromatography and characterized by spectral analysis. The most abundant phaeopigment in the sediment traps, a phaeo-phorbide-like molecule of intermediate polarity (phaeophorbide a₃), peaked in abundance in the water column below the 1% isolume for PAR (60-80 m) and showed the highest rate of photooxidation. This phaeopigment was least abundant in the seston when phytoplankton was dominated by prymnesiophytcs but increased its abundance in plankton dominated by diatoms. This distribution suggests that larger grazers feeding on diatoms are the main producers of this phaeopigment.