Satellite-derived measurements of spatial and temporal chlorophyll-a variability in Funka Bay, southwestern Hokkaido, Japan

Chlorophyll-a (chl-a) concentration has an important economic effect in coastal and marine environments on fisheries resources and marine aquaculture development. Monthly climatologies the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) derived chl-a from February 1998 to August 2004 around Funka Bay were used to investigate the spatial and temporal variability of chl-a concentrations. SeaWiFS-derived suspended sediment, MODIS derived sea surface temperature (SST), solar radiation and wind data were also analyzed. Results showed two distinct chlorophyll blooms in spring and autumn. Chl-a concentrations were relatively low (<0.3 mg m⁻³) in the bay during summer, with high concentrations occurring along the coast, particularly near Yakumo and Shiraoi. In spring, chl-a concentrations increased, and a large (>2 mg m⁻³) phytoplankton bloom occurred. The spatial and temporal patterns were further confirmed by empirical orthogonal function (EOF) analysis. About 83.94% of the variability could be explained by the first three modes. The first chl-a mode (77.93% of the total variance) explained the general seasonal cycle and quantified interannual variability in the bay. The spring condition was explained by the second mode (3.89% of the total variance), while the third mode (2.12% of the total variance) was associated with autumn condition. Local forcing such as the timing of intrusion of Oyashio water, wind condition and surface heating are the mechanisms that controlled the spatial and temporal variations of chlorophyll concentrations. Moreover, the variation of chlorophyll concentration along the coast seemed to be influenced by suspended sediment caused by resuspension or river discharge.     

Estimating Chlorophyll-<Emphasis Type="Italic">a</Emphasis> Vertical Profiles from Satellite Data and the Implication for Primary Production in the Kuroshio Front of the East China Sea

An algorithm was evaluated for estimating primary production in the Kuroshio front of the East China Sea. The algorithm involves three principal inputs: chlorophyll-a (Chl-a) vertical profile, water column photosynthetic parameter and underwater irradiance parameter. We construct empirical models for estimating those three inputs from sea surface variables accessible by means of satellite remote sensing. Types of Chl-a vertical profile were closely associated with water mass features, and sea surface temperature seemed to be a potential variable to distinguish profile types. The consequence of the deep Chl-a maximum (DCM) presence was investigated by comparing the vertically non-uniform Chl-a profile against the uniform Chl-a profile in terms of the integrated biomass and primary production estimates. Since the DCM in the frontal region occurred in a relatively shallow layer with relatively high light level, allowing intensive photosynthetic processes to take place in the DCM layer. In contrast, as the DCM in the Kuroshio region occurred in the low-light, deep layer, it contributed less to the integrated primary production. We inferred that the DCM formation is more important in the frontal region than in the Kuroshio region, as they potentially contributed within 30.9% (±9.1%) and 20.9% (±5.4%) to the integrated primary production in the frontal and the Kuroshio regions, respectively. Such different degrees in the DCM contribution was then revealed by the higher integrated primary production in the frontal region than in the Kuroshio region.     

Development of a Neural Network Algorithm for Retrieving Concentrations of Chlorophyll, Suspended Matter and Yellow Substance from Radiance Data of the Ocean Color and Temperature Scanner

An algorithm is presented to retrieve the concentrations of chlorophyll a, suspended pariclulate matter and yellow substance from normalized water-leaving radiances of the Ocean Color and Temperature Sensor (OCTS) of the Advanced Earth Observing Satellite (ADEOS). It is based on a neural network (NN) algorithm, which is used for the rapid inversion of a radiative transfer procedure with the goal of retrieving not only the concentrations of chlorophyll a but also the two other components that determine the water-leaving radiance spectrum. The NN algorithm was tested using the NASA's SeaBAM (SeaWiFS Bio-Optical Mini-Workshop) test data set and applied to ADEOS/OCTS data of the Northwest Pacific in the region off Sanriku, Japan. The root-mean-square error between chlorophyll a concentrations derived from the SeaBAM reflectance data and the chlorophyll a measurements is 0.62. The retrieved chlorophyll a concentrations of the OCTS data were compared with the corresponding distribution obtained by the standard OCTS algorithm. The concentrations and distribution patterns from both algorithms match for open ocean areas. Since there are no standard OCTS products available for yellow substance and suspended matter and no in situ measurements available for validation, the result of the retrieval by the NN for these two variables could only be assessed by a general knowledge of their concentrations and distribution patterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Distribution of nitrogenous nutrients and denitrifiers strains in estuarine sediment profiles of the Tanshui River, northern Taiwan

Chemical profiles of both oxidized (nitrate and sulfate) and reduced (ammonium, sulfide, acid-volatile sulfide [AVS], and pyrite) materials and the corresponding distribution of denitrifier microbial communities were measured at low tide in sediments at Guandu in the estuary of the Tanshui River, northern Taiwan in August 2002. Denitrifier strains were isolated for physiological and phylogenic analyses. Based on the distribution of nitrogenous compounds and denitrifier abundances, the vertical profile of Guandu sediments could be separated into four layers: a mixed layer (the top 1 cm of depth, respectively containing 0.82–2.37 and 535.9–475.0 μM of nitrate and ammonium), a nitrate-concentrated layer (1–5 cm in depth, 2.37–0.53 and 475.0–1192.1 μM, respectively), a denitrifier-aggregation layer (5–7 cm in depth, 0.53–0.72 and 1192.1–1430.1 μM, respectively), and an ammonium-enriched layer (7–12 cm in depth, 0.72–0.78 and 1430.1–2196.6 μM, respectively). Denitrifier strains were detected in all layers except for the mixed layer. A variety of metabolic processes by these strains may occur in different layers. Bacillus jeotgali-, Bacillus sphaericus-, and Bacillus firmus-related strains isolated from the nitrate-concentrated layer may be involved in the nitrification-denitrification coupling process due to the relatively low nitrate concentrations (maximum = 2.37 μM), and may contribute to denitrification not nitrification. Bacillus bataviensis- and B. jeotgali-related strains isolated from the denitrifier-aggregation layer comprised the predominant denitrifier population (3.64 × 10⁴ cells/g of denitrifier abundance). They possess the ability of dissimilatory nitrate reduction to ammonium (DNRA). Bacillus jeotgali-related strains and two newly identified strains of GD0705 and GD0706 isolated from the ammonium-enriched layer possibly use fermentative processes as the main metabolic pathway instead of denitrification when nitrate is scarce, and this further supports the high ammonium concentrations (up to 2.20 mM) found in the Guandu sediments. In addition, spore formation also enhances the chance of survival of these strains in the face with such a nitrate-deficient environment.     

Distribution and seasonal variation of concentrations of particulate carbohydrates and uronic acids in the northern Indian Ocean

Suspended particulate matter (SPM) samples were collected from the surface seawaters at 31 stations, and from various depths (2 to 1000 m) at 9 locations in the northern Indian Ocean during various seasons. SPM samples were analyzed for total particulate carbohydrate (TPCHO), total particulate uronic acid (TPURA) and total particulate neutral carbohydrate (TPNCHO) concentrations and composition. Strong spatial, temporal and depth related variations were evident in the distribution of these compounds. In surface waters, concentrations of TPCHO, TPNCHO, and TPURA varied from 0.57 to 3.58 μM C, 0.11 to 2.34 μM C, and from 0.01 to 0.31 μM C, respectively, and accounted for 2.6 to 34.6%, 2 to 24.5%, and 0.2 to 6.3% of POC, respectively, whereas the TPURA accounted for 4.7 to 22.7% of TPCHO. Concentrations and yields of both TPNCHO and TPURA decreased rapidly in the upper 100 m of the water column suggesting their utilization by heterotrophic organisms. Glucose was the most abundant constituent of the TPNCHO. Glucose mole fraction decreased while that of other monosaccharides, especially galactose, arabinose, mannose, rhamnose and fucose increased in the upper 100 m water. Below this depth, mole fraction of glucose increased while that of other sugars decreased with the increasing water depth. Generally, high C:N ratios were associated with low yields of carbohydrates and uronic acids. Inverse correlation between the mole fractions of arabinose plus xylose and rhamnose plus fucose indicates the importance of biogenic and terrestrial organic matter input to the Bay of Bengal. TPURA are surface-active in nature and thus may play an important role in coagulation of particles and macromolecules. The observed spatial and seasonal variations of these compounds may be due to differences in phytoplankton biomass, nutrient status, and the influence of terrestrial material.     

西太平洋叶绿素a浓度对气候变化响应概念模型初探

西太平洋海区浮游植物的分布受气候变化影响,在不同时空尺度上呈现不同的变化。本研究旨在通过对历史文献及数据资料分析,建立气候变化响应概念模型来探讨Chl-a、海水表面温度(SST)及营养盐如何响应长期气候变化。分析了西太平洋不同区域Chl-a与气候变化相关因子SST及海水营养盐(硝酸盐)的相关性,对模型参数进行选择及验证,来探讨该海区Chl-a是如何响应长期气候变化。结果表明,K2站位Chl-a浓度与SST、硝酸盐浓度呈显著正相关关系,与该海区存在上升流有关;而S1、XT站位均呈现负相关关系,可能与海水水温升高导致层化加剧、营养输入减少有关。本研究为进一步完善和优化西太平洋海区的浮游植物的气候变化响应模型奠定基础。     

春季西南黄海与绿潮相关的物理环境特征

Massive green tides caused by Ulva prolifera in the Yellow Sea have occurred every summer since 2007 and have caused huge economic losses for local governments. The Subei(North Jiangsu Province, China) Shoal, with its large-scale Porphyra aquaculture, has been regarded as the most important source of U. prolifera for green tides.To reveal the physical mechanisms of floating and drifting algae in this area, the characteristics of the current, the temperature, the salinity and suspended particulate matter(SPM) in the southwestern Yellow Sea, especially in the Subei Shoal, were studied. The topography of the radial sand ridges in the Subei Shoal constrains the features of the currents and causes net longitudinal and latitudinal movements. The longitudinal net movement is a dominant dynamic factor that can bring U. prolifera into offshore waters. The amount of gas that is produced by algae during photosynthesis determines whether U. prolifera can float well on the sea surface after it is disposed into the water from Porphyra aquacultural apparatus. The Subei Shoal is characterized by a high turbidity, which can result in significant light attenuation and affect the photosynthesis together with the buoyancy of a U.prolifera in the water. According to satellite remote sensing data from 2012, the three-month-averaged surface SPM(April, May and June) in the Subei Shoal was 140 mg/dm3, and the north of the Subei Shoal(the north of34.5°N), it was 11 mg/dm3. According to the monthly averaged surface SPM in April, the transparency in the Subei Shoal was only 0.1 m, but it often exceeded 2.0 m outside of the Subei Shoal. The results explain why the floating ability of U. prolifera increases significantly once the green algae drifted outside the Subei Shoal.     

泥蚶快速生长季生化代谢物的变化特征

研究了象山港泥蚶(Tegillarca granosa)快速生长季(2020年5—11月)糖原、游离氨基酸和脂肪酸等代谢物的组成、含量及其变化,并对其营养特征变化进行了分析。结果显示,7—9月为泥蚶快速生长期,此期前后泥蚶生长缓慢。泥蚶肌肉糖原含量约5.6~11.1mg/g;牛磺酸、丙氨酸、谷氨酸和天冬氨酸是其主要的游离氨基酸;不饱和脂肪酸含量丰富,且主要为多不饱和脂肪酸。生长过程中几种生化代谢物含量变化显著:5—7月间,糖原含量显著降低、氨基酸和脂肪酸组成发生显著变化。7—9月间,糖原含量、生糖和呈味氨基酸含量显著升高、饱和及单不饱和脂肪酸含量显著降低,但脂肪酸组成结构无显著差异。11月,氨基酸及多不饱和脂肪酸含量均显著升高。11月泥蚶具有高的营养品质。本研究为泥蚶养殖管理及水产品营养研究提供参考。     

夏季珠江口邻近海域表层浮游植物的碳叶绿素比值及其碳含量

Chlorophyll a(Chl a),particulate organic carbon(POC)and biogenic silica(BSi)were determined in coastal waters adjacent to the Zhujiang(Pearl)River Estuary(ZRE)during summer,in order to examine the C:Chl a ratio of phytoplankton and phytoplankton carbon in the plume-impacted coastal waters during summer,as well as to assess the relative contribution of diatoms to the phytoplankton biomass,by the regression between Chl a,POC and BSi.Our results showed that the C:Chl a ratio(g/g)of phytoplankton was high(up to 142),likely due to high light intensity and nutrient limitation.The river plume input stimulated phytoplankton growth,especially diatoms,resulting in higher relative contribution of phytoplankton carbon(55%)and diatoms(34%)to POC in the plume-impacted region than those(33%and 13%)in high salinity area,respectively.Phytoplankton carbon(up to 538μg/L)in the plume-impacted region was much higher than that(<166μg/L)in high salinity area.Our findings were helpful to improve the biogeochemical model in coastal waters adjacent to the ZRE.     

吕宋海峡西部深海盆内孤立波潜标观测研究

Mesoscale eddies have been suggested to have an impact on biological carbon fixation in the South China Sea （SCS）. However, their overall contribution to primary production during the spring inter-monsoon pe riod is still unknown. Based on large-scale biological and environmental in situ observations and synchro nous remote sensing data, the distribution patterns of phytoplankton biomass and the primary production, and the role of mesoscale eddies in regulating primary production in different eddy-controlled waters were investigated. The results suggested that the surface chlorophyll a concentrations and water column inte grated primary production （IPP） are significantly higher in cyclonic eddies and lower in the anticyclonic eddies as compared to that in non-eddy waters. Although eddies could affect various environmental factors, such as nutrients, temperature and light availability, nutrient supply is suggested to be the most important one through which mesoscale eddies regulated the distribution patterns of phytoplankton biomass and pri mary production. The estimated IPP in cyclonic and anticyclonic eddies are about 29.5% higher and 16.6% lower than the total average in the whole study area, respectively, indicating that the promotion effect of mesoscale cold eddies on the primary production was much stronger than the inhibition effect of the warm eddies per unit area. Overall, mesoscale eddies are crucial physical processes that affect the biological car bon fixation and the distribution pattern of primary production in the SCS open sea, especially during the spring inter-monsoon period.     

饲料蛋白质水平对拟目乌贼生长前期的生长性能、肌肉成分和酶活的影响

以鱼粉、豆粕和明胶为主要蛋白源配制成蛋白质水平分别为31.5%、35.0%、38.5%、42.0%、45.5%、49.0%的试验饲料。选取初始均重(3.99±0.08)g的拟目乌贼(Sepia lycidas)540只,随机分成6组,每组3个重复,每个重复30只。结果表明:拟目乌贼的生长性能指标(增重率、特定生长率、成活率)均在饲料蛋白质水平为45.91%时达到最佳,除与蛋白质水平为49.72%时差异不显著(P0.05)外,与其他各组均有显著差异(P0.05)。饲料系数随蛋白质水平的升高呈先降后升的趋势,在饲料蛋白质水平为45.91%时达到最低,显著低于除49.72%组外的其他各组;蛋白质效率随着饲料中蛋白质水平的升高而显著下降(P0.05)。饲料蛋白质水平对肥满度与肝体比影响不显著(P0.05)。胃蛋白酶、胰蛋白酶、肠道脂肪酶和肝脏超氧化物歧化酶活性,随饲料蛋白质水平的增加呈先升后降的趋势,均在饲料蛋白质水平为45.91%时达到最高,胃蛋白酶和胰蛋白酶活性除与蛋白质水平为42.22%时差异不显著(P0.05)外,与其他各组均有显著差异(P0.05);脂肪酶和肝脏超氧化物歧化酶活性与其他各组均有显著差异(P0.05),而肠道淀粉酶活性则相反。肝脏谷丙转氨酶和谷草转氨酶活性随饲料蛋白质水平的增加呈先升后稳定的趋势,均在饲料蛋白质水平为49.72%时达到最大,显著高于除45.91%组外的其他各组(P0.05);而饲料蛋白质水平对碱性磷酸酶活性影响不显著(P0.05)。乌贼肌肉粗蛋白质在饲料蛋白质水平45.91%时含量最高,显著高于除49.72%组外的其他各组(P0.05);粗脂肪含量最低,显著低于其他各组(P0.05);而肌肉水分和粗灰分含量不受饲料蛋白质水平的影响(P0.05)。拟目乌贼生长前期(4~10 g)配合饲料适宜的蛋白质水平为45.91%。     

西南印度洋龙旂热液区神盾螺共附生微生物多样性分析

深海热液区的极端环境促使热液区生物形成了独特的生存机制,即与微生物的共附生关系。本文利用高通量测序技术分析了与西南印度洋龙旂热液区神盾螺（Gigantopelta aegis）共附生微生物的种类及功能。基于16S rRNA基因 V3-V4区扩增子测序结果发现：①神盾螺共附生菌中99.99%都属于细菌域,丰度最高的是变形菌门γ-,ε-,和α-变形菌纲;②神盾螺个体Ga1和Ga3的共附生菌群落中以γ-变形菌为主,个体Ga2 中以ε-变形菌为主,表明在同一热液区生活的不同个体间其共附生菌种类也存在较大差异;③宏转录组测序结果与扩增子测序结果基本一致,即神盾螺共附生细菌中变形菌门相对丰度最高,同时发现了高丰度的硫代谢、氢代谢、甲烷代谢以及环境胁迫应答基因。神盾螺共附生微生物的研究将有助于探究深海热液喷口生物的生存和适应策略,为进一步研究奠定基础。