基于FlowCam影像和YOLOv3深度学习模型的多纹膝沟藻检测

海洋中的有害藻华,包括微藻形成的赤潮和褐潮以及大型藻类形成的绿潮和金潮,已成为一类突出的海洋生态灾害问题。2021年11—12月,山东半岛东北部海域发生多纹膝沟藻(Gonyaulax polygramma)形成的大规模赤潮,导致海带养殖严重受损,亟待构建有针对性的赤潮监测预警体系。本文以多纹膝沟藻为对象,尝试应用流式影像仪(FlowCam)结合卷积神经网络模型YOLOv3,分别对含有多纹膝沟藻的浓缩海水样品、含有多纹膝沟藻和链状亚历山大藻(Alexandrium catenella)的浓缩海水样品,以及含有多纹膝沟藻活细胞及空壳的浓缩海水样品进行了检测实验,探究了基于藻种影像的深度学习模型在赤潮原因种检测方面的应用潜力。结果表明,在以FlowCam获取的影像数据集训练3万次后,YOLOv3对多纹膝沟藻表现出较好的识别能力,对浓缩海水样品中目标藻种识别的平均精度为88.2%;当样品中存在与多纹膝沟藻形态相似的链状亚历山大藻时,模型对多纹膝沟藻识别的平均精度下降为76.6%,对两种微藻同时进行训练和检测,可将对多纹膝沟藻识别的平均精度提高至84.6%。对于低温下出现脱壳现象的多纹膝沟藻,模型对海水中活细胞识别的平均精度为86.7%,对空壳识别的平均精度87.8%,将多纹膝沟藻活细胞与空壳分别识别的平均精度均值(87.3%)高于将两者统一作为多纹膝沟藻进行检测的识别精度(84.2%),整体识别精度提升3.1%。综合相关结果可以看出,FlowCam与深度学习模型相结合在赤潮监测和研究中具有重要应用潜力。     

海洋微藻中脂肪酸的气相色谱分析

本文以正十九碳酸作内标,用ＨＣＩ－ＣＨ３ＯＨ对海洋微藻进行抽提酯化后做毛细管气相色谱分析。方法的重现性各脂肪酸的相对偏差为０．３％－１１．６％,回收率为８５．７％－１０３．３％,仪器稳定性的相对偏差为０．２－３．１％。。     

三种北极微藻对不同温度的适应性研究

为了研究北极微藻对不同环境温度的适应性,对分离自北极王湾地区的三种微藻-玛氏骨条藻(Skeletonema marinoi)、小球藻(Chlorella sp.)和衣藻(Chlamydomonas sp.)在不同温度条件下(0℃、4℃和8℃)的生长曲线和抗氧化酶系统进行了测定.结果表明微藻对温度的适应性因种而异:玛氏骨条藻在4℃具有最快生长速率,最高的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)酶活性,及最低的丙二醛(MDA)含量;小球藻的最快生长速率及酶活均在8℃时,MDA含量最低值出现在0℃;衣藻生长情况相差不大,MDA含量的最低值出现在8℃.抗氧化酶系统变化规律也因藻种及温度而异--在0℃与4℃变化时,玛氏骨条藻抗氧化酶系统的三个指标的差异极显著(P<0.01);在0℃与8℃变化时,玛氏骨条藻与小球藻的SOD活性的差异显著(P<0.05),其余两个指标差异不显著;衣藻在三个温度下的三个指标差异均不显著.总体而言,三种藻对三个温度的适应性均较好:其MDA的含量均较低,三种藻各自具有独特的生理代谢机制来适应不同的温度环境.     

Effect of linear alkylbenzene sulfonate (LAS) and atrazine on marine microalgae

Five marine microalgae (Tetraselmis chuii, Rhodomonas salina, Chaetoceros sp., Isochrysis galbana (T-iso) and Nannochloropsis gaditana), in the same biovolume quantity, were exposed to 72h growth-inhibition tests with atrazine and LAS. In all cases, the inhibition effect of atrazine was higher than that of LAS up to two orders of magnitude higher in the case of T. chuii. In a second part of the study, initial cellular densities for each microalga strain and fixed organic compound concentration were varied, and results show density has a clear influence in growth inhibition tests. Finally, the sum of all data obtained in the study was expressed in terms of "toxic cellular quota" (mass of chemical substance per cell). The result was a sigmoid curve with a good fit, including the two main factors in toxicity tests, initial cellular density and contaminant concentration. This toxic cellular quota exhibits a general tendency to increase with cell volume/size.     

温度、光照、pH值对后棘藻生长及脂肪酸含量的影响

报道了环境因子对富含 EPA (2 0∶ 5ω3)的海洋微藻后棘藻 (Ellipsoidion sp.) 70 - 0 1的生长速度、总脂及脂肪酸含量的影响。结果表明 ,后棘藻具有较快的生长速度和较高的脂肪酸含量 ,总脂含量为 31～ 36 % ,主要脂肪酸为 14∶ 0、16∶ 0、16∶ 1、18∶ 1ω9、18∶ 1ω7、18∶ 2 ω6、2 0∶ 4 ω6、2 0∶ 5ω3。生长的温度范围为 15～ 30℃ ,2 5℃时生长速度最快。温度对总脂含量影响很小 ,但对EPA和 PUFA含量影响较大。在 2 5℃时有最大的 EPA和 PUFA含量。适宜光强为 10 8.75μmolm-2 s-1～ 2 4 4 .15μmolm-2 s-1,在 145.54μmolm-2 s-1时 EPA产率较大。在起始 p H6 .5～ 9范围内 ,p H8.5时有最大的生长速率和总脂含量 ,而 EPA和 PUFA在起始 p H7.5时最大 ,分别占脂肪酸的 18.77%和 2 3.38%。实验条件下后棘藻 EPA产率最大的条件为温度 2 5℃ ,光强 145.54μmolm-2 s-1,p H为 7.5～ 8.5。     

温度对四种海洋微藻脂肪酸组成的影响

对在不同温度下培养的4种海洋微藻脂肪酸的气相色谱分析表明，不同微藻的脂肪酸组成及其不饱和程度受温度影响的差别较大。在本实验条件下，随着温度升高，球等革命金藻、盐生杜氏藻、三角褐指藻的总多不饱和脂肪酸（TPUFA）百分含量及脂肪酸平均双键数（MDB）均呈下降趋势，其总单不饱和脂肪酸（TMUFA)和总饱和脂肪酸（TSFA）百分含量则呈增加趋势；随着温度提高小球藻TPUFA百分含量和脂肪酸平均双键数先降低后增加，在20℃时出现最小值。     

Benthic metabolism and the fate of dissolved inorganic nitrogen in intertidal sediments

We determined patterns of benthic metabolism and examined the relative importance of denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) as sinks for nitrate (NO₃⁻) in intertidal sediments in the presence and absence of benthic microalgal (BMA) activity. By influencing the activity of BMA, light regulated the metabolic status of the sediments, and, in turn, exerted strong control on sediment nitrogen dynamics and the fate of inorganic nitrogen. A pulsed addition of ¹⁵N-labeled NO₃⁻ tracked the effect and fate of dissolved inorganic nitrogen (DIN) in the system. Under illuminated conditions, BMA communities influenced benthic fluxes directly, via DIN uptake, and indirectly, by altering the oxygen penetration depth. Under dark hypoxic and anoxic conditions, the fate of water column NO₃⁻ was determined largely by three competing dissimilatory reductive processes; DNF, DNRA, and, on one occasion, anaerobic ammonium oxidation (anammox). Mass balance of the added ¹⁵N tracer illustrated that DNF accounted for a maximum of 48.2% of the ¹⁵NO₃⁻ reduced while DNRA (a minimum of 11.4%) and anammox (a minimum of 2.2%) accounted for much less. A slurry experiment was employed to further examine the partitioning between DNF and DNRA. High sulfide concentrations negatively impacted rates of both processes, while high DOC:NO₃⁻ ratios favored DNRA over DNF.     

基于熵权的产生物柴油微藻开发潜力评价

结合青岛地区不同季节室外温度变化特点,采用熵权法对9株微藻利用发电厂废气生产生物柴油的户外开发潜力进行评估。选取油脂产率、油脂组成、CO2耐受性、破壁难易度和温度适应性5项指标,根据实验室测得的数据进行计算,得出春冬季以上5项指标的权重分别为0.261、0.002、0.059、0.211和0.467,而夏秋季以上5项指标的权重分别为0.098、0.001、0.022、0.079和0.801。在此权重的基础上,得出在春冬季节开发潜力最大的藻株为微拟球藻(Nannochloropsis sp.ZL-12),在夏秋季节开发潜力最大的藻株为球等鞭金藻(Isochrysis galbana C5001)。本方法为户外大规模开发生物柴油的微藻藻种选择提供了一个有效的思路。     

几种微藻对方斑东风螺浮游幼虫生长和变态的影响

本文报道了4种微藻不同浓度对方斑东风螺幼虫生长和变态的影响.结果表明,幼虫对4种微藻都能摄食,当投喂不同浓度的牟氏角毛藻、湛江叉鞭金藻时,摄食角毛藻(20×104cells/cm3)生长最快达77.9μm/d、变态率52.5%;摄食金藻(20×104cells/cm3)变态率最高达59.0%、生长速度70.4μm/d,随金藻浓度的上升,幼虫生长速度和变态率都上升.投喂不同浓度的青岛大扁藻时,最高变态率是24.4%(1×104cells/cm3),最快生长速度是59.3μm/d(7×104cells/cm3),随扁藻浓度的上升,幼虫的生长速度上升而变态率下降.摄食云微型藻幼虫生长缓慢,浮游期全部死亡.幼虫单独摄食角毛藻、金藻和扁藻,其首次出现变态个体的日龄分别是10、11、14d,而完成变态的日龄分别是22~23d、21~23d和26~28d.比较上述4种微藻,角毛藻和金藻是方斑东风螺幼虫的最适饵料,根据大水体人工育苗的具体条件,合适浓度应为角毛藻(5~10)×104cells/cm3,金藻(10~15)×104cells/cm3.而扁藻不宜单独投喂,作为辅助饵料较合适.     

Overview and status of estuarine microphytobenthos ecological research in South Africa

This article presents a historical overview of estuarine microphytobenthos (MPB) research in South Africa published over the period 1950 to the present, highlighting major milestones, challenges and estuarine management problems, as well as future research needs within the South African context. The studies that were covered comprise peer-reviewed books and journal articles on relevant research conducted in any estuarine environment during the period reviewed. There was a general increase in MPB research outputs over the decades, from only two publications in the 1950s, to over 20 outputs between 2010 and the present. Whereas the MPB studies in South Africa cover a broad spectrum of themes, the research priorities in these works have changed from taxonomically biased studies to those of ecologically based research. Research in the 1950s and 1960s was exclusively taxonomic in nature, with the first ecological investigation incorporating MPB being produced in the 1970s. By the 1980s, ecological studies dominated the research outputs and this trend has persisted to the present. The 1990s and 2000s saw the rise of research into the role of fresh water as a driver of MPB dynamics, whereas the period 2010 to the present saw an increase in more diverse ecological themes, ranging from an autecological investigation to food-web studies and the assessment of multiple drivers of MPB dynamics. However, the majority of studies have focused on either diatoms or estimates of overall MPB biomass. Moreover, there is a regional underrepresentation that runs broadly along biogeographic lines, with the bulk of the work having been conducted in the warm-temperate and subtropical zones of South Africa. Challenges and future research needs for the region are outlined, as is the need to expand MPB research to include other aspects of the biology and ecology of this flora.