Uncoupled distributions of transparent exopolymer particles (TEP) and dissolved carbohydrates in the Southern Ocean

Transparent exopolymer particles (TEP) are formed by the assembly of dissolved precursors, mainly mono and polysaccharides (DMCHO and DPCHO) that are released by microorganisms. Although TEP formation plays a significant role in carbon export to deep waters and can affect gas exchange at the sea surface, simultaneous measurements of TEP and their precursors in natural waters have been scantly reported. In this study, we described the spatial (vertical and regional) distribution of TEP, DMCHO and DPCHO in a region located around the Antarctic Peninsula, assessed their contribution to the total organic carbon pool, and explored their relationships with phytoplankton (with chlorophyll a (chl a) as a proxy) and bacteria. TEP concentration ranged from undetectable values to 48.9 µg XG eq L^− 1 with a mean value of 15.4 µg XG eq L^− 1 (11.6 µg TEP-C L^− 1). DMCHO and DPCHO showed average values of 4.3 µmol C L^− 1 and 8.6 µmol C L^− 1, respectively. We did not find simple relationships between the concentrations of TEP and dissolved carbohydrates, but a negative correlation between DMCHO and DPCHO was observed. Chl a was the best regressor of TEP concentration in waters within the upper mixed layer, while bacterial production was the best regressor of TEP concentration below the mixed layer, underlining the direct link between these particles and bacterial activity in deep waters.     

夏季闽东沿海水体中透明胞外聚合颗粒物的分布特征及影响因素

透明胞外聚合颗粒物(TEP)在海洋微食物网和海洋碳循环中发挥着重要作用。本文针对夏季闽东沿海TEP的分布特征及影响因素进行研究。结果表明,闽东沿海TEP含量(以黄原胶为标准物质计算,后同)范围为25.2～935.5 μg/L,平均值为(201.8±177.9) μg/L。整体而言,TEP的分布表现为近岸高、远岸低,表层TEP含量相对于底层要低。相关性分析显示,研究海域TEP含量与浊度和营养盐(硅酸盐、磷酸盐、硝酸盐、亚硝酸盐和铵盐)浓度呈正相关,与pH、溶解氧浓度和小型浮游生物量呈负相关。分级叶绿素a结果显示,相对于其他尺寸浮游植物,调查海域小型浮游生物可能对TEP含量的贡献最大。相比于开阔大洋中TEP主控因素为浮游植物而言,夏季闽东海域TEP主要由浮游植物在衰退阶段产生,其分布主要受颗粒物再悬浮作用影响。该结果不仅进一步阐明了近岸海域与开阔大洋TEP影响因素的区别,并且对我国近海海域不同区域TEP分布研究空白进行了补充。     

北白令海透明胞外聚合颗粒物的含量与来源

透明胞外聚合颗粒物(TEP)是海水中大量存在的黏性颗粒物质,它对于海洋颗粒物的聚集、有机碳的埋藏、食物网物质的传递、痕量金属的清除与迁出等均起着重要作用。本研究开展了夏季北白令海陆架、陆坡和海盆区透明胞外聚合颗粒物含量和分布的研究。结果表明,北白令海TEP含量介于34~628 mg/m3(Xeq)之间,其中陆架、陆坡和海盆区TEP的平均含量分别为240, 145和83 mg/m3(Xeq),整体呈现由陆架向外海降低的趋势。在陆坡和海盆区,TEP含量随着深度的增加而降低,但在陆架近底层水中,观察到TEP高含量的特征,与近底层水高的TSM, POC相对应。TEP与荧光强度、TSM、POC等的关系分析显示,研究海域TEP存在两个来源,其一为海洋上层水体的浮游生物,其主要贡献于陆架上层、陆坡和海盆水体;其二为陆架沉积物的底栖生物,其通过沉积物再悬浮贡献于陆架近底层水。     

Biogeochemistry and carbon mass balance of a coccolithophore bloom in the northern Bay of Biscay (June 2006)

Primary production (PP), calcification (CAL), bacterial production (BP) and dark community respiration (DCR) were measured along with a set of various biogeochemical variables, in early June 2006, at several stations at the shelf break of the northern Bay of Biscay. The cruise was carried out after the main spring diatom bloom that, based on the analysis of a time-series of remotely sensed chlorophyll-a (Chl-a), peaked in mid-April. Remotely sensed sea surface temperature (SST) indicated the occurrence of enhanced vertical mixing (due to internal tides) at the continental slope, while adjacent waters on the continental shelf were stratified, as confirmed by vertical profiles of temperature acquired during the cruise. The surface layer of the stratified water masses (on the continental shelf) was depleted of inorganic nutrients. Dissolved silicate (DSi) levels probably did not allow significant diatom development. We hypothesize that mixing at the continental slope allowed the injection of inorganic nutrients that triggered the blooming of mixed phytoplanktonic communities dominated by coccolithophores (Emiliania huxleyi) that were favoured with regards to diatoms due to the low DSi levels. Based on this conceptual frame, we used an indicator of vertical stratification to classify the different sampled stations, and to reconstruct the possible evolution of the bloom from the onset at the continental slope (triggered by vertical mixing) through its development as the water mass was advected on-shelf and stratified. We also established a carbon mass balance at each station by integrating in the photic layer PP, CAL and DCR. This allowed computation at each station of the contribution of PP, CAL and DCR to CO₂ fluxes in the photic layer, and how they changed from one station to another along the sequence of bloom development (as traced by the stratification indicator). This also showed a shift from net autotrophy to net heterotrophy as the water mass aged (stratified), and suggested the importance of extracellular production of carbon to sustain the bacterial demand in the photic and aphotic layers.     

Environmental influence on transparent exopolymer particles and the associated carbon distribution across northern South China Sea

Microgels are plankton-derived transparent exopolymer particles (TEP) and have a significant impact on global marine carbon cycle. We investigated the influence...     

Transparent exopolymer particles (TEP) as a component of hydrothermal plume particle dynamics

Transparent exopolymer particles (TEP) have recently been recognized as a class of sticky particles that often stimulate macroaggregate formation. Until now, TEP studies were focused on surface waters, particularly in association with diatom blooms. This is the first report of TEP concentrations in an open ocean deep-sea hydrothermal plume environment. The occurrence of TEP in deep water demonstrates its existence in an environment that is devoid of growing phytoplankton, the organisms generally regarded as TEP's primary source. The main objective of this study was to investigate the presence and potential abundance of TEP within hydrothermal plumes over the Juan de Fuca Ridge. Samples for TEP and bacteria were collected from CTD-rosette casts through hydrothermal plumes over the Juan de Fuca Ridge during the summers of 1999 and 2000. Concentrations of TEP and bacteria within the hydrothermal plumes were significantly greater than in background seawater. TEP number and volume concentrations reported here are low compared to reported values for shallow environments, but are substantially higher than published reports of TEP in other deep water environments. Ratios of TEP anomalies to temperature anomalies (a conservative hydrothermal tracer) increased with distance from the apparent plume source, suggesting that TEP are produced within the aging hydrothermal plumes. Potential TEP sources associated with hydrothermal plumes are discussed. TEP in hydrothermal plumes could stimulate in situ aggregate formation, support populations of attached bacteria, and serve as a potential food source to zooplankton.     

Biogeochemical study of a coccolithophore bloom in the northern Bay of Biscay (NE Atlantic Ocean) in June 2004

The present paper synthesizes data obtained during a multidisciplinary cruise carried out in June 2004 at the continental margin of the northern Bay of Biscay. The data-set allows to describe the different stages of a coccolithophore bloom dominated by Emiliania huxleyi. The cruise was carried out after the main spring phytoplankton bloom that started in mid-April and peaked in mid-May. Consequently, low phosphate (PO₄ < 0.2 μM) and silicate (DSi < 2.0 μM) concentrations, low partial pressure of carbon dioxide (pCO₂) and high calcite saturation degree in surface waters combined with thermal stratification, probably favoured the blooming of coccolithophores. During the period of the year our cruise was carried out, internal tides induce enhanced vertical mixing at the continental shelf break leading to the injection of inorganic nutrients to surface waters that probably trigger the bloom. The bloom developed as the water-column stratified and as the water mass was advected over the continental shelf, following the general residual circulation in the area. The most developed phase of the bloom was sampled in a remote sensed high reflectance (HR) patch over the continental shelf that was characterized by low chlorophyll-a (Chl-a) concentration in surface waters (<1.0 μg L^?1), high particulate inorganic carbon (PIC) concentration (～8 μmol L^?1) and coccolithophore abundance up to 57 × 10⁶ cells L^?1. Transparent exopolymer particles (TEP) concentrations ranged between 15 and 75 μg C L^?1 and carbon content of TEP represented up to 26% of the particulate organic carbon (POC; maximum concentration of 15.5 μmol L^?1 in the upper 40 m). Integrated primary production (PP) ranged between 210 and 680 mg C m^?2 d^?1 and integrated calcification (CAL) ranged between 14 and 140 mg C m^?2 d^?1, within the range of PP and CAL values previously reported during coccolithophore blooms in open and shelf waters of the North Atlantic Ocean. Bacterial protein production (BPP) measurements in surface waters (0.3–0.7 μg C L^?1 h^?1) were much higher than those reported during early phases of coccolithophore blooms in natural conditions, but similar to those during peak and declining coocolithophorid blooms reported in mesocosms. Total alkalinity anomalies with respect to conservative mixing (ΔTA) down to ?49 μmol kg^?1 are consistent with the occurrence of biogenic precipitation of calcite, while pCO₂ remained 15–107 μatm lower than atmospheric equilibrium (372 μatm). The correlation between ΔTA and pCO₂ suggested that pCO₂ increased in part due to calcification, but this increase was insufficient to overcome the background under-saturation of CO₂. This is related to the biogeochemical history of the water masses due to net carbon fixation by the successive phytoplankton blooms in the area prior to the cruise, hence, the investigated area remained a sink for atmospheric CO₂ despite calcification.     

2019年夏秋季温州近海海水透明胞外聚合颗粒物（TEP）的分布及影响因素分析

透明胞外聚合颗粒物（TEP）具有高黏性、低密度和高碳氮比等特性,在颗粒有机物的聚集以及食物网循环中发挥着重要作用。为了解近岸海域TEP的分布动力学规律与机制,本文对温州近海夏秋季节水体中透明胞外聚合颗粒物的分布进行调查,并结合多项环境要素的主成分分析与相关性分析,探究了浙江南部近岸海域TEP分布的影响因素。结果显示,温州近海TEP秋季平均含量明显高于夏季,夏季TEP分布变化主要受陆地径流（瓯江）作用影响,而秋季主要受闽浙沿岸流影响。受沿岸流影响,秋季TEP的主要来源可能是其他海域以及底层颗粒物再悬浮。此外,由浮游植物释放的TEP对夏季的POC贡献最大,而秋季外源性TEP对POC的贡献较夏季有所升高。     

东海PN断面透明胞外聚合颗粒物分布特征及来源研究

透明胞外聚合颗粒物（TEP）是凝聚网的重要组成部分甚至核心,在微尺度范围上形成了水环境结构的重要梯度,对于元素地球化学生物循环、碳沉降以及食物网有着举足轻重的作用。本文研究了东海典型断面PN透明胞外聚合颗粒物的分布特征及来源。结果表明:东海典型断面PN透明胞外聚合颗粒物含量介于28~376 μg Xeq./L之间,平均值为（115±67）μg Xeq./L;呈现出明显的夏季 > 冬季 > 秋季 > 春季的季节变化特征以及近岸 > 外海和底层 > 表层的分布趋势。通过对比透明胞外聚合颗粒物分布趋势和硅藻、甲藻分布趋势以及统计分析得出,东海典型断面PN透明胞外聚合颗粒物主要来源于硅藻,甲藻贡献不大;而外海TEP的来源可能主要由超微型浮游植物贡献。     

夏季珠江口透明胞外聚合颗粒物分布特征

本文研究夏季珠江口透明胞外聚合颗粒物(TEP)含量以及分布特征.结果表明,珠江口TEP含量(以黄原胶物质的量计算,下同)范围在85.0-1234.9μg·L-1之间,平均值为690.9μg·L-1.表层和底层TEP均值分别为562.3μg·L-1和778.2μg·L-1,大部分站位表层TEP含量略低于底层.TEP在表层分布自上游至下游逐渐递增,而向外海以及人海口东西两侧延伸逐渐降低.内河口为底层TEP含量高值区,虎门附近S3站TEP含量最高.TEP与不同粒径浮游植物叶绿素a的相关性分析表明微型浮游植物(粒径3-20μm)可能对珠江口TEP贡献较大.珠江口TEP/Ch1a比值与活性硅酸盐、硝酸盐、铵盐和总磷浓度呈现负相关性;表层TEP/Ch1a比值与盐度呈现正相关性,这表明盐度和营养盐可能是影响TEP含量的重要因素.     

长江口邻近海域透明胞外聚合颗粒物浓度和沉降速率研究

透明胞外聚合颗粒物（Transparent exopolymer particles,TEPs）在海洋中分布广泛,其沉降被认为是海洋中生物碳沉降的途径之一。本研究于2011年春季和夏季调查了长江口邻近海域TEPs的浓度和沉降速率,并且估算了其碳沉降通量。研究发现,TEPs浓度春季介于40.00~1040.00 μg Xeq L^-1,平均值为209.70±240.93 μg Xeq L^-1;夏季介于56.67~1423.33 μg Xeq L^-1,平均值为433.33±393.02 μg Xeq L^-1。两个季节,TEPs在水华站位的浓度明显高于非水华站位。相关性分析表明,TEPs与水体叶绿素a浓度呈显著正相关性,表明在调查区浮游植物是TEPs的主要生产者。TEPs沉降速率在春季介于0.08~0.57 m d^-1,平均值为0.28±0.14 m d^-1;夏季介于0.10~1.08 m d^-1,平均值为0.34±0.31 m d^-1。经估算,TEPs碳沉降通量春季介于4.95~29.40 mg C m^-2 d^-1,平均值为14.66±8.83 mg C m^-2 d^-1;夏季介于6.80~30.45 mg C m^-2 d^-1,平均值为15.71±8.73 mg C m^-2 d^-1。TEPs的碳沉降通量可以占到浮游植物碳沉降通量的17.81%~138.27%。水华站位TEPs的碳沉降通量明显高于非水华站位,这是由于水华站位较高的TEPs浓度及沉降速率所致。本研究表明,TEPs的沉降在长江口邻近海域是碳沉降的有效途径,在相应的碳沉降相关研究中应该被考虑进来。     

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

In June/July 1994 a study was made of a small bloom of the coccolithophorid Emiliania huxleyi in an area of the North Sea to the east of the Shetland Islands. Observations on the hydrography of the study area indicated the bloom was associated with Atlantic water and was confined to an area in which a stable shallow mixed layer had formed. There was no evidence to suggest association of horizontal physical structure with the bloom development. High cell densities of >1– cells dm⁻³, together with low concentrations of PIC (<50 μg dm⁻³) and detached liths (2– liths cm⁻³) indicated that the bloom was studied at an early stage of development. Biochemical and physiological observations indicated active growth was taking place. The results presented are discussed in comparison with previous studies carried out in both oceanic and shelf seas.     

Effect of iron enrichment on the dynamics of transparent exopolymer particles in the western subarctic Pacific

Dynamics of transparent exopolymer particles (TEP) was studied during the first in situ iron-enrichment experiment conducted in the western subarctic Pacific in July–August 2001, with the goal of evaluating the contribution of TEP to vertical flux as a result of increased primary production following iron enrichment in open ocean ecosystems. Subsequent to the enhancement of phytoplankton production, we observed increase in TEP concentration in the surface layer and sedimentation of organic matter beneath it. Vertical profiles of TEP, chlorophyll a (Chl a) and particulate organic carbon (POC) were obtained from six depths between 5 and 70 m, from a station each located inside and outside the enriched patch. TEP and total mass flux were estimated from the floating sediment traps deployed at 200 m depth. Chl a and TEP concentrations outside the patch varied from 0.2 to 1.9 μg L⁻¹ and 40–60 μg XG equiv. L⁻¹, respectively. Inside the patch, Chl a increased drastically from day 7 reaching the peak of 19.2 μg L⁻¹ on day 13, which coincided with the TEP peak of 189 μg XG equiv. L⁻¹. TEP flux in the sediment trap increased from 41 to 88 mg XG equiv. m⁻² d⁻¹, with 8–14% contribution of TEP to total mass flux. This forms the basic data set on ambient concentrations of TEP in the western subarctic Pacific, and evaluation of the effect of iron enrichment on TEP.     

Satellite observations of the coccolithophorid bloom in the Barents Sea

The data of the color satellite ocean scanners SeaWiFS and MODIS-Aqua provide evidence that a sharp increase in the backscattering coefficient of the suspended particles occurred within a considerable part of the Barents Sea during the last decade in July–September. Judging from all the indications, this increase can be attributed to the coccolithophorid bloom. In 2004, we were able to directly substantiate this attribution. Water samples for determining the phytoplankton concentration were collected in the course of observations from onboard the R/V Professor Stokman in the western Barents Sea during the fast growth of the backscattering coefficient of the suspended particles according to the satellite data. They revealed the high concentration of the coccolithophorids and coccoliths. The satellite data indicate the strong variability of the areas of the bloom in time and space. We were able to show the interrelation of the backscattering coefficient of the suspended particles and the sea surface temperature.     

Quaternary sedimentary regime on the Berthois Spur (Bay of Biscay)

A study of cores from the Celtic Margin shows that high terrigenous accumulation rates occurred at the end of isotopic stage 3 and during isotopic stage 2. These high rates prevailed during rapid changes from relatively warm conditions (Älesund interstadial) to maximum glacial condition. The input of terrigenous material may have culminated with the blockage of the North Sea by an ice sheet and the diversion of NW European flumes toward the Celtic Margin. The uppermost sediments are in a state of overconsolidation as the consequence of erosional processes following the episod of high sediment supply.     

Phytoplankton spring bloom of the Gironde plume waters in the Bay of Biscay: early phosphorus limitation and food-web consequences

During the spring 1995 (2–25 May), a cruise was carried on the RV Poseidon (Germany) on the continental shelf of the south Bay of Biscay. The objective was a comprehensive study of the planktonic food web within the Gironde plume waters. In these waters phosphate was present at very low concentrations (undetectable to < 0.1 μmol.L⁻¹), whereas nitrate, silicate and ammonium concentrations were much higher (several μmol·L⁻¹ for nitrate and silicate and 0.5 to 1.0 μmol·L⁻¹ for ammonium). The size distribution of the phytoplankton biomass (estimated from chlorophyll a measurements by high performance liquid chromatography) and primary production (measured by ¹⁴C in situ method) showed a great proportion of small (40 to 70 % < 3 μm) and active autotrophic cells (growth rates estimated from 0.4 to 0.8 d⁻¹ for the entire euphotic layer). Considering the very high values of NO₃-N:PO₄-P ratios and the high C:P and N:P ratios for the particulate organic matter, it is suggested that an early phosphorus depletion limits the spring bloom phytoplankton and particularly the new production (nitrate uptake coming from the Gironde waters).From these results and other simultaneous observations on the heterotrophic processes (such as grazing of microzooplankton), we can conclude that the planktonic food web would be close to a maintenance system as defined by Platt et al. The possible generalisation of these results for each spring is discussed with respect to the scarcity of previous and reliable phosphate data.     

胶州湾赤潮生物种类及其生态分布特征

近年来,胶州湾赤潮频繁发生,对海水养殖业、海洋环境乃至人类健康与安全都构成威胁,作者于1997--1998年间对胶州湾东北部富营养化海域进行赤潮专项调查,报道了赤潮生物69种,其中已发生过的赤潮种类有7种,分析了中肋骨条藻Skeletonema costatum、圆筛藻Coscinodiscus sp.、冰河拟星杆藻(日本星杆藻)Asterionellopsis glacialis、劳氏角毛藻Chaetoceros lorenzianus、红色中缢虫Mesodinium rubrum等主要赤潮生物的生态分布特征.