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.     

温度、盐度和光照对浒苔生长和光合作用的影响

Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceeding in the Yellow Sea since 2007. It was, however, unclear how the detached U. prolifera responded and resumed growing after they detached from its original habitat. In this study, we investigated the growth and photosynthetic response of the detached U. prolifera to various temperature, salinity and irradiance in the laboratory. The photosynthetic rate of the detached U. prolifera was significantly higher at moderate temperature levels(14–27°C)and high salinity(26–32), with optimum at 23°C and 32. Both low(14°C) and highest temperature(40°C), as well as low salinity(8) had adverse effects on the photosynthesis. Compared with the other Ulva species, U. prolifera showed higher saturated irradiance and no significant photoinhibition at high irradiance, indicating the great tolerance of U. prolifera to the high irradiance. The dense branch and complex structure of floating mats could help protect the thalli and reduce photoinhibition in field. Furthermore, temperature exerted a stronger influence on the growth rate of the detached U. prolifera compared to salinity. Overall, the high growth rate of this detached U. prolifera(10.6%–16.7% d~(–1)) at a wide range of temperature(5–32°C) and salinity(14–32) implied its blooming tendency with fluctuated salinity and temperature during floating. The environmental parameters in the southwestern Yellow Sea at the beginning of green tide were coincident with the optimal conditions for the detached U. prolifera.     

Tracing the settlement region of massive floating green algae in the Yellow Sea

Outbreaks of large-scale green tides formed by Ulva prolifera in the Yellow Sea (YS) cause heavy ecological damages and huge economic losses. However, the ecological consequences of green tides remain poorly understood due to the lack of knowledge on the settlement region of massive green algae floating in the YS. In this study, we established a method to trace the settlement region of floating green algae, using 28-isofucosterol preserved in sediment as the specific biomarker for green algae. Sterols including 28-isofucosterol in surface sediment samples collected during an investigation in the YS and the Bohai Sea (BS) in August 2015 were analyzed using gas chromatography coupled with a mass spectrometer (GC-MS). Based on the content of 28-isofucosterol in sediment samples, the potential settlement region of fl oating green algae was identifi ed in the sea area southeast to the Shandong Peninsula around the sampling site H06 (122.66°E, 36.00°N). This paper presents a first result on the settlement region of floating green algae in the YS for providing a solid basis to elucidate the ecological consequences of green tides in the area.     

EST-SSR标记的开发及其在南黄海浒苔研究中的应用

Ulva species can grow rapidly in nutrient-rich habitats causing green tides and marine fouling. A more complete understanding of the reasons behind these outbreaks is urgently required. Accordingly, this study attempts to use microsatellite markers based expressed sequence tag（EST） to analyze the genetic variation of several Ulva prolifera populations in the South Yellow Sea of China. Two hundred and thirty-eight SSRs were identified from 8 179 unique ESTs（6 203 newly sequenced and 1 976 downloaded from NCBI database） and 37 primer pairs were successfully designed according to the ESTs; 11 pairs were selected to detect the genetic diversity and relationship of 69 attached U. prolifera samples and 13 free-floating samples collected from coastal and off-coast areas of the South Yellow Sea. The results of cross-species transferability showed that six of the 11 EST-SSR primers could give good amplification in other five Ulva species and the average allele number was 4.67. Genetic variation analysis indicated that all 82 U. prolifera samples were clearly divided and most samples collected from the same site clustered together as a group in the dendrogram tree produced by unweighted pair-group mean analysis（UPGMA） method and the cluster results showed some consistency with the geographical origins. In addition, 13 free-floating samples（except HT-001-2） were grouped as a single clade separated from the attached samples.     

《中国海洋湖沼学报》（英文版，SCI-E收录） 2011年第6期论文导读

Bacterial diversity in surface water of the Yellow Sea during and after a green alga tide 郭丛、李富超、姜鹏、刘兆普、秦松：2008年5-8月,黄海中部爆发了大规模的绿潮（浒苔Ulva（Enteromorpha）prolifera...     

Two drifting paths of Sargassum bloom in the Yellow Sea and East China Sea during 2019-2020

The macroalgal blooms of floating brown algae Sargassum horneri are increasing in the Yellow Sea and East China Sea during the past few years. However, the annual pattern of Sargassum bloom is not well characterized. To study the developing pattern and explore the impacts from hydro-meteorologic environment, high resolution satellite imageries were used to monitor the distribution, coverage and drifting of the pelagic Sargassum rafts in the Yellow Sea and East China Sea from September 2019 to Au...     

Radium-traced nutrient outwelling from the Subei Shoal to the Yellow Sea: Fluxes and environmental implication

The Subei Shoal is the largest sandy ridge in the southern Yellow Sea and is important source for nutrient loading to the sea. Here, the nutrient fluxes in the Subei Shoal associated with eddy diffusion and submarine groundwater discharge（SGD） were assessed to understand their impacts on the nutrient budget in the Yellow Sea. Based on the analysis of 223 Ra and 224 Ra in the field observation, the offshore eddy diffusivity mixing coefficient and SGD were estimated to be 2.3×10⁸ cm     

黄海苏北浅滩海域春夏季浮游植物时空分布及其控制生态因子

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×10~3 to 269.78×10~3 cell/L with an average of 41.80×10~3 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×10~3 cell/L with the range of 1.78×10~3 to 574.96×10~3 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO_4-Si(DIN/SiO_4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.     

Effects of Ulva prolifera dissipation on the offshore environment based on remote sensing images and field monitoring data

Outbreaks of Ulva prolifera have continued in the South Yellow Sea of China(SYS) since 2007, becoming a serious marine ecological disaster. Large amounts of U. prolifera drift to the coast of the Shandong Peninsula to dissipate under the action of southeast monsoons and ocean surface currents. This causes serious harm to the ecological environment and economic activities of coastal cities. To investigate the impact of U. prolifera dissipation, this study extracted the spatiotemporal distribution...     

Photosynthetic response of floating Ulva prolifera to diurnal changes of in-situ environments on the sea surface

During yellow sea green tide outbreak, the thalli of Ulva prolifera drifted more than 350 km on the sea surface from off shore of Jiangsu Province to Qingdao city, where they were exposed to complex changes of local environments. The purpose of this study is to investigate the response of the thalli to diurnal changes of environments on the sea surface, and a sea surface environment simulator (SSES) was designed to simulate the natural environment of floating U . prolifera mat. A control experiment is designed in the laboratory, which was processed under suitable conditions (20°C for temperature, 72 μmol photons/(m 2 ·s) for light intensity and 30 for salinity), and an in-situ research was conducted to study the photosynthetic responses of floating U . prolifera to diurnal changes of environments. The results show that the photosynthetic efficiency of the thalli decreased gradually with time, and decreased rapidly after 14:00 local time (LT). After exposed to the environment on the sea surface for 6 h, the photosynthetic activity of the thalli decreased significantly. Furthermore, physiological-level and molecular-level experiments revealed that non-photochemical quenching (NPQ), cyclic electron flow (CEF) and energy redistribution between PSI and PSII all played an important role in the strong photosynthetic plasticity of U . prolifera . NPQ is the most important photoprotective responses to environmental changes before 12:00 LT. The results also confirmed that the CEF and energy redistribution between PSI and PSII are the main synergistic eff ects for the thalli to adapt to the environmental changes when the process NPQ cannot work. And the result can further reveal the reason why U . prolifera can adapt to the living condition of long distance drift on the sea surface. The findings of this research could provide a theoretical basis for explaining outbreaks of the green tide and instructing the management of the problem.     

中国苏北浅滩海域定生海藻繁殖体的来源

自2007年以来,黄海海域已连续爆发大规模浒苔绿潮并造成了严重的经济损失。在苏北浅滩条斑紫菜养殖筏架上的定生浒苔被认为是漂浮绿潮藻的主要来源。然而,现阶段对筏架定生绿藻的种源基础并不清楚。因此,在本研究中,我们通过现场调查结合室内试验来揭示了筏架定生绿藻的繁殖体源。同时,为了对黄海大规模绿潮进行防控,我们对防止绿藻在紫菜养殖筏架的附着做了相关研究。结果表明,（1）包括浒苔、缘管浒苔、扁浒苔、曲浒苔以及盘苔这五种海藻的微观繁殖体共同存在于苏北浅滩海域的水体及沉积物中,而且在不同时期它们的比例变化明显。（2）经过去皮处理后的毛竹可明显抑制浒苔微观繁殖体的附着。通过本研究,我们明确分布于苏北浅滩海域的绿藻微观繁殖体是黄海大规模绿潮的种源基础。同时,我们为从源头防控黄海大规模绿潮的发生提供了一个可行的手段。     

黄海浒苔绿潮防灾减灾现状与早期防控展望

截至2019年,浒苔绿潮连续12年大规模暴发,对近海生态系统、沿岸环境与社会经济造成严重影响,已经成为黄海最严重的生态环境问题。本文总结了黄海浒苔绿潮防灾减灾现状与成效,分析了存在的问题,然后基于对该绿潮起源与成因的认识,将其早期分为3个关键过程,即浒苔微观繁殖体在养殖设施上的着生与生长过程,定生浒苔脱离附着基形成漂浮浒苔过程,浅滩漂浮浒苔进入深水区形成大面积绿潮过程。最后分别从加强新材料与技术研发防控绿藻着生、强化养殖设施回收管理严控定生绿藻落滩、浅滩汇聚通道拦截打捞等3种途径提出了早期防控措施建议,以期为黄海浒苔绿潮的源头防控提供科学依据。     

2013年春季苏北浅滩紫菜养殖区绿藻和微观繁殖体的分布现状

为了揭示苏北浅滩紫菜养殖区附着绿藻和绿藻微观繁殖体的分布现状,从2013年三月到五月份对苏北浅滩紫菜养殖区及附近海域进行航次调查。结果表明, 绿藻微观繁殖体在水体和沉积物中广泛分布,水体中的平均值为267株/L,沉积物中的平均值为43株/g。调查期间,紫菜养殖区筏架上附着绿藻的生物量持续增长。在紫菜筏架上发现有浒苔,缘管浒苔,盒管藻三种绿藻,其优势种为盒管藻,其次是浒苔。研究表明,绿潮发生早期在苏北浅滩海域存在绿藻微观繁殖体和附着绿藻,这将为中国绿潮治理提供理论支撑。     

苏北浅滩筏架附生绿藻群落结构变化及与环境因子的相关性探究

苏北浅滩是研究浒苔绿潮早期形成机制的重要区域,该区域紫菜养殖筏架上附生绿藻的群落结构变化对浒苔绿潮的发生具有重要影响,环境因素在其中发挥了重要作用.为了探明导致苏北浅滩绿藻群落结构变化的主要环境因素,本文通过分子生物学和种群生态学方法对筏架附生绿藻群落结构进行了研究,结果表明:(1)苏北浅滩筏架附生绿藻群落主要由浒苔(...     

苏北浅滩沉积物中的大型绿藻微观繁殖体的垂直分布和物种多样性

本研究通过在2017年秋冬季组织实施的2个绿潮种源调查航次,研究苏北浅滩紫菜养殖区沉积物中的大型绿藻微观繁殖体的垂直分布和物种多样性。对沉积物中的微观繁殖体的定量实验结果表明:表层泥样中绿藻微观繁殖体的丰度最高,随着深度的增加迅速降低。在9月份表层沉积物中丰度为9±2ind./g,而在11月份表层丰度达到98±25ind./g;与9月份相比, 11月份浅滩沉积物中绿藻繁殖体数量呈现出显著升高的趋势。通过对51个绿藻样品的分子鉴定发现:沉积物中存在石莼属(Ulva)、尾孢藻属(Urospora)、盘苔属(Blidingia)等大型绿藻的微观繁殖体;数量占优是石莼属繁殖体,主要包括曲浒苔(Ulva flexuosa)、浒苔(Ulva prolifera)、扁浒苔(Ulva compressa)、缘管浒苔(Ulva linza);其中曲浒苔占据的比例最高,在9和11月份分别达到80.94%和73.33%。在2个调查航次中,都从沉积物中发现了绿潮浒苔的微观繁殖体,这些微观繁殖体是绿潮浒苔在苏北浅滩种源维持的重要方式和关键阶段,也构成了黄海浒苔绿潮连年暴发的"种子库"。     

黄海海域大规模绿潮成因与应对策略——“鳌山计划”研究进展

在青岛海洋科学与技术国家实验室"鳌山计划"支持下,本项目围绕黄海大规模浒苔绿潮的防控减灾,联合山东和江苏两地多个单位协作攻关,于2016年到2018年展开了多学科交叉研究,通过对绿潮藻浒苔(Ulva prolifera)的附着、入海等行为的加密观测,在大规模浒苔绿潮成因机制和防控策略方面取得了重要进展,确认了苏北浅滩源地,确认本海区大量紫菜(Pyropiayezoensis)栽培筏架提供的大面积合适附着基、典型的富营养化环境特点以及北向风生流是黄海大规模浒苔绿潮形成的重要条件。本项目解决了以下几方面的问题:1.锁定关键时段和海域并开展打捞船与无人机配合打捞;2.发现苏北浅滩存在独特浒苔种源;3.定量化研究了紫菜筏架拆除时人为去除筏架及绠绳上的附生绿藻量,明确这一过程大大促进了浒苔大量集中入海,成为浒苔绿潮形成的重要环节;4.定量化研究了浒苔在向北漂移,生物量和分布不断增加的过程;5.依据对浒苔緑潮的源头及其早期发生、发展几个关键过程的科学认识,提出了设置三道防线进行浒苔绿潮防控的策略以及在苏北浅滩开展浒苔绿潮初始生物量源头控制的具体建议。6.评价了浒苔绿潮对生态环境和养殖业危害的同时,关注了高生物量输入对受灾地可能带来生物北侵的生态风险。7.为保障2018年青岛上合峰会,项目组先期提交了绿潮防控建议,部署和开展的各项研究和现场调查结果为绿潮的预测防控提供了有力支撑。同时本项目还针对浒苔绿潮灾害的年际变化、马尾藻(Sargassumsp.)金潮灾害加剧、南黄海"三潮齐发"的复杂态势等新问题展开了观测与研究,为进一步制订更科学高效的防灾减灾方案,阐明全球变化和人类活动影响下的我国近海藻华灾害的演变奠定了基础。     

黄海绿潮浒苔漂浮生态型的发现与启示

黄海绿潮已经成为常态化发生的海洋生态灾害。遗传分析结果表明,黄海绿潮藻主体由浒苔(Ulva prolifera)的单一群体构成。基于其特殊的基因型、表型,及其占据的独特生态位与生活方式,将其命名为"漂浮生态型"(floating ecotype)。浒苔漂浮生态型的发现,为黄海绿潮关键生态学过程的量化表征提供了重要抓手。基于SCAR特异分子标记的示踪研究表明,在绿潮早期浒苔入海阶段,苏北浅滩紫菜筏架发挥了重要作用;在海上暴发漂移阶段,漂浮生态型在漂浮藻中具有极高的优势度。上述发现提示,黄海绿潮存在重要的生物学成因,应加强针对漂浮生态型适应性特征及其遗传基础的比较研究。鉴于漂浮生态型在山东半岛南岸已零星定殖,提出应关注由于种源北侵和紫菜栽培产业北移带来的潜在风险。上述科学认识对于深刻理解黄海绿潮的成因与发生机制、建立可行的灾害防控措施、科学预测黄海绿潮的演变趋势具有重要意义。     

浒苔孢子在不同材料基质上的附着萌发差异性研究

本研究针对黄海绿潮早期发生过程,以浒苔生殖细胞附着生长特征为切入点,以其主要原因藻种浒苔(Ulva prolifera)为材料,对比研究了不同材料附着基质对浒苔孢子附着萌发的影响。发现孢子在2—6h内的附着率达到80%,尤其是在前2h内的附着速率最快,而且在不同材料的基质上都能完成附着萌发,但萌发数量存在显著差异性,孢子在紫菜养殖筏架相关材料(塑料、竹片、尼龙网衣、塑料网衣)上的萌发率显著高于浅滩、礁石和养殖池相关材料(细砂、海泥、石块)。浒苔孢子还可以在藻段上完成附着萌发,而橡胶和鱼粉袋相关材料对浒苔孢子的萌发存在抑制作用。对比浒苔孢子和配子的萌发特性发现两者有异同点,两者在塑料、竹片等筏架相关材料上萌发率均较高,而孢子在藻段以及橡胶浸出液和鱼粉溶液中的萌发数均显著高于配子。本研究发现紫菜养殖筏架更有利于浒苔孢子的附着萌发,这进一步说明苏北浅滩数十万亩的紫菜养殖筏架在绿潮早期形成过程中为浒苔孢子提供了重要的附着基质。本研究结果将为探讨紫菜养殖筏架在绿潮早期发生过程中的重要作用,并为养殖筏架防附着材料的选用提供参考。     

江苏近岸紫菜养殖筏架区定生绿藻群落结构及其受控因素

基于2010年10月至2011年4月对苏北紫菜养殖筏架区定生绿藻及环境因素调查数据,分析研究了紫菜筏架上定生绿藻种群结构和数量变化及重要环境因子对其的影响并估算了调查区绿藻总生物量.结果表明,筏架上定生绿藻种类有浒苔(Ulva prolifera)、盒管藻(Capsosiphon groenlandicus)、缘管浒苔(Ulva linza)、肠浒苔(Ulva intestinalis)、条浒苔(Ulva clathrata)和扁浒苔(Ulva compressa).绿藻生物量变化呈倒抛物线型,4月份为主高峰14898吨,11月份为次高峰2034吨,2月份最低,仅为729吨,3-4月份绿藻几乎呈暴发性增长.种类多样性随季节变化有很大差异,养殖筏架刚入海的9、10月份,绿藻种类丰富,生物多样性高;12月至笠年2月,尽管生物量很低,但仍是多种并存;3-4月份随着生物量的猛增,种类多样性降至最低,盒管藻优势地位明显,生物量比例最大能到80%,浒苔比例呈指数增长,达20%～40%.水温对绿藻生物量及种类演替有直接调控作用,在水温< 10℃时,绿藻即能快速生长;而盐度作用不明显.开展紫菜筏架上定生绿藻群落动态变化及其生物量的估算,为追溯南黄海大规模绿潮发源地提供佐证,为绿潮预防和治理提供基础数据支撑.