Application of functional data analysis to investigate seasonal progression with interannual variability in plankton abundance in the Bay of Fundy,Canada     

Takayoshi Ikeda  Michael Dowd  Jennifer L. Martin 《Estuarine, Coastal and Shelf Science》2008

The statistical technique of functional data analysis (FDA) is applied to a time series analysis of plankton monitoring data. The analysis is focused on revealing patterns in the seasonal cycle to assess interannual variability of several different taxonomic groups of plankton. Cell concentrations of diatom, dinoflagellate and zooplankton abundances from the Bay of Fundy, Canada provide the observations for analysis. FDA was performed on the log-transformed abundance data as a new approach for treating such types of sparse and noisy data. Differences in the seasonal progression were seen, with peak numbers, timings and abundance levels varying for the three groups as determined by curve registration and higher order derivatives using the objectively fit FDA curves. Nonmetric multidimensional scaling was used to capture seasonal variation among years. These results were further assessed in terms of dominant species and the relationships between groups for different seasons and years. It is anticipated that the easy to use, general and flexible technique of FDA could be applied to a wide variety of marine ecological data that are characterized by missing values and non-Gaussian distributions.  相似文献   

Recent moon jelly (Aurelia sp.1) blooms in Korean coastal waters suggest global expansion: examples inferred from mitochondrial COI and nuclear ITS-5.8S rDNA sequences     

Ki  Jang-Seu; Hwang  Dae-Sik; Shin  Kyoungsoon; Yoon  Won Duk; Lim  Donghyun; Kang  Young Shil; Lee  Yoon; Lee  Jae-Seong 《ICES Journal of Marine Science》2008,65(3):443-452

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BASIC: Baltic Sea cyanobacteria. An investigation of the structure and dynamics of water blooms of cyanobacteria in the Baltic Sea—responses to a changing environment     

Lucas J. Stal  Patrizia Albertano  Birgitta Bergman  Klaus von Brckel  John R. Gallon  Paul K. Hayes  Kaarina Sivonen  Anthony E. Walsby 《Continental Shelf Research》2003,23(17-19):1695

The blooms of cyanobacteria that develop each summer in the Baltic Sea are composed of two functional groups, namely the small-sized picocyanobacteria (Synechococcus sp.) and the larger, colony-forming, filamentous N₂-fixing cyanobacteria. The former encompassed both red (phycoerythrin-rich) and blue-green (phycocyanin-rich) species. The majority of the picocyanobacteria measured less than 1 μm and this size fraction comprised as much as 80% of the total cyanobacterial biomass and contributed as much as 50% of the total primary production of a cyanobacterial bloom. The picocyanobacteria are incapable of fixing N₂, do not possess gas vesicles and are not toxic. However, a small filamentous Pseudanabaena sp. that could potentially fix N₂ was isolated from the picocyanobacteria fraction. The larger cyanobacteria may form surface scums because they possess gas vesicles that make them buoyant. Although their biomass was less than the picocyanobacteria, they therefore form the more conspicuous and nuisance-forming part of the bloom. The larger cyanobacteria were composed mainly of three different species: Nodularia spumigena, Aphanizomenon flos-aquae and Anabaena sp. These all belong to the heterocystous, N₂-fixing cyanobacteria. N. spumigena and A. flos-aquae were the dominant species; only N. spumigena was toxic. Although individual Nodularia filaments showed a range of different phenotypes, they all belong to one species as judged from 16S rDNA sequencing. Through determination of the genotypes of many individual Nodularia filaments, it was shown that this population was not clonal and that horizontal exchange of genetic information occurs. N. spumigena and A. flos-aquae were different with respect to their photosynthetic and N₂-fixing potentials. Depending on prevailing environmental conditions, these differences would promote the proliferation of one species over the other and hence would determine overall the toxicity of a bloom. Daily integrals of photon irradiance rather than temperature determined the onset of bloom formation. During a bloom, the diazotrophic cyanobacteria fixed N₂ at a rate that was 10–20% in excess of their own demand for N. Picocyanobacteria assimilated most of this excess N as shown by ¹⁵N incorporation. During bloom conditions, the diazotrophic cyanobacteria met about 50% of the N demand of the total cyanobacterial community. The picocyanobacteria were predominantly N-limited while the diazotrophic cyanobacteria were probably iron limited. These findings allow us to understand the formation of toxic cyanobacterial blooms and also to develop tools to predict bloom formation.  相似文献   

The variations in optical properties of CDOM throughout an algal bloom event     

Jun Zhao  Wenxi Cao  Guifen Wang  Dingtian Yang  Yuezhong Yang  Zhaohua Sun  Wen Zhou  Shaojun Liang 《Estuarine, Coastal and Shelf Science》2009

For studies in bio-optical oceanography, visible light properties by classes of dissolved organic matter should be characterized. The regional adjustment of model parameters is one approach which is being widely used to refine bio-optical models. In the present study, buoy and laboratory data were acquired, and during the 15-day observation period an algal bloom event occurred. The absorption coefficient of CDOM at 443 nm, a_g(443), changed in the range of 0.09–0.35 m⁻¹ and 0.1–0.34 m⁻¹ for two depths, 0.32 m and 2.3 m., respectively, throughout the entire period. CDOM absorption was larger for bloom conditions than for non-bloom conditions. In addition, the fraction of CDOM in total absorption was higher during the bloom event than that of non-bloom conditions. The spectral slope of CDOM absorption, S_g, regressed over 400–500 nm, ranged from 0.015 to 0.0185 nm⁻¹ with an average of 0.0166 nm⁻¹. CDOM fluorescence intensity (Fcdom) was obtained using an internal Raman standard and varied over the range of 467.44–1538.23 in relative units. Variations in Fcdom showed a similar pattern to that of CDOM absorption. A robust non-linear relationship between Fcdom and CDOM absorption was found, with a correlation coefficient of 0.893, throughout the whole observation. An attempt to describe S_g with absorption showed a promising consequence that can be described with a negative correlation during the bloom, however, without any distinguishable tendency for non-bloom time span. A two-band ratio algorithm was also carried out for retrieving CDOM absorption. The variations in optical properties of CDOM may be related to the complicated environment in the estuarine waters, which may result from different sources of CDOM.  相似文献   

Imprudent fishing harvests and consequent trophic cascades on the West Florida shelf over the last half century: A harbinger of increased human deaths from paralytic shellfish poisoning along the southeastern United States, in response to oligotrophication?     

J.J. Walsh  C.R. TomasK.A. Steidinger  J.M. LenesF.R. Chen  R.H. WeisbergL. Zheng  J.H. LandsbergG.A. Vargo  C.A. Heil 《Continental Shelf Research》2011,31(9):891-911

Within the context of ubiquitous overfishing of piscivores, recent consequent increments of jellyfish and clupeids have occurred at the zooplanktivore trophic level in the eastern Gulf of Mexico (GOM), after overfishing of one of their predators, i.e. red snapper. Initiation of a local trophic cascade thence led to declines of herbivore stocks, documented here on the West Florida shelf. These exacerbating world-wide trophic cascades have resulted in larger harmful algal blooms (HABs), already present at the base of most coastal food webs. Impacts on human health have thus far been minimal within nutrient-rich coastal regions. To provide a setting for past morbidities, consideration is given to chronologies of other trophic cascades within eutrophic, cold water marine ecosystems of the Scotian Sea, in the Gulf of Alaska, off Southwest Africa, within the Barents, White, and Black Seas, in the Gulf of Maine, and finally in the North Sea. Next, comparison is now made here of recent ten-fold increments within Florida waters of both relatively benign and saxitoxic HABs, some of which are fatal to humans. These events are placed in a perspective of other warm shelf systems of the South China and Caribbean Seas to assess prior and possible future poison toxicities of oligotrophic coastal habitats. Past wide-spread kills of fishes and sea urchins over the Caribbean Sea and the downstream GOM are examined in relation to the potential transmission of dinoflagellate saxitoxin and other epizootic poison vectors by western boundary currents over larger “commons” than local embayments. Furthermore, since some HABs produce more potent saxitoxins upon nutrient depletion, recent decisions to ban seasonal fertilizer applications to Florida lawns may have unintended consequences. In the future, human-killing phytoplankton, rather than relatively benign fish-killing HABs of the past, may be dispersed along the southeastern United States seaboard.  相似文献   

基于视频监控图像的环巢湖蓝藻实时动态监测     

马腾耀  肖鹏峰  张学良  段洪涛  邱银国 《湖泊科学》2022,34(6):1840-1853

蓝藻的防控与治理是湖泊水环境、水生态管理的重要内容,实时获取蓝藻的空间分布信息对于降低蓝藻灾害风险具有重要意义.针对地面调查费时费力、卫星遥感监测粒度较粗且时效性不强等问题,本文提出了一种基于视频监控网络的湖泊蓝藻实时监测技术.基于环巢湖视频监控网络的33个功能摄像机,研究如何从视频图像中实时、准确提取蓝藻的分布信息.为克服不同摄像头的观测角度不一致、光照强度和背景条件不一致等诸多挑战,在视频图像蓝藻表征分析的基础上,通过多尺度深度网络进行图像粗粒度分类,区分蓝藻与浑浊、阴影水体;基于随机森林进行蓝藻精细化识别,克服蓝藻的强异质性.最后以渔政站沿岸水域的日均蓝藻覆盖率和月均蓝藻覆盖率为统计单位,开展了巢湖沿岸蓝藻的动态监测.研究成果可为科学制定蓝藻治理方案提供技术支撑.  相似文献   

黄海浒苔绿潮及其溯源研究进展   总被引：7，自引：0，他引：7  

刘峰  逄少军 《海洋科学进展》2012,30(3):441-449

2007-2012年,黄海连续6a暴发了大规模绿潮。分析了过去5a国内外对黄海绿潮以及绿潮形成种浒苔的研究进展,并总结了对黄海绿潮浒苔溯源的主要观点。结合国内外对绿潮浒苔生物学研究结果,深入分析了大规模黄海绿潮暴发的关键要素(绿潮形成种、近海海水富营养化和其它海洋环境因子)以及生物生态学机制,根据已知的结果推演黄海绿潮全年发生发展过程。据此,认为黄海绿潮大暴发与江苏省近岸海域海水富营养化密切相关,辐射沙洲的浒苔微观繁殖体(孢子、配子及其不同发育程度的显微个体)在绿潮暴发过程中扮演重要角色。  相似文献   

Surveys of mussels (Mollusca: Lamellibranchia) in the firth of Thames, 1961–67     

J. P. C. Greenway 《新西兰海洋与淡水研究杂志》2013,47(2):304-317

Surveys are described which were made to determine distribution and relative density of stocks of mussels, Perna canaliculus Gmelin (Lamellibranchia: Anisomyaria; Mytilidae), in the Firth of Thames, North Island, New Zealand, during the late autumn‐early winter of each year 1961–63 and 1965–67.

Two dredges available for sampling were tested against one another over similar ground. Both gave comparable results, but although the one chosen was never actually calibrated, it gave consistent results which allowed relative changes of abundance to be studied.

In 1961, 206 stations were sampled on a grid of 1 square mile which covered most of the Firth. Early results showed that the densest beds were along the western shore line; there were only small patches of mussels off Coromandel and along the eastern shore. A well‐stocked and readily identifiable area of 2 square miles off Matingarahi Point was selected for more intensive sampling on a 1/16 square‐mile grid. Samples collected there annually showed a rapid decline of the population after commercial dredging in 1961–62; there was no substantial regeneration on the bottom after this, though satisfactory settlement occurred above the bottom on experimental moorings. Declining yields are shown for other areas (Ponui Island and New Brighton) which were also sampled on a 1/16 square‐mile grid.

Commercial landings of mussels decreased rapidly after 1961, and have not recovered. There have been no regular landings since 1966 but a promising private experiment in small‐scale cultivation is described.  相似文献   

Phosphorus in suspended matter and sediments of a hypertrophic lake. A case study: Lake Dianchi,China   总被引：1，自引：0，他引：1  

Hu Jun  Liu Jiantong  Liu Yongding 《Environmental Geology》2009,58(4):833-841

From June 2004 to December 2004, Lake Dianchi, which had large scale of cyanobacterial blooms was investigated in order to study P-fractionation in the suspended matter and the sediment. The investigation improves our understanding of phosphorus in Lake Dianchi and the relationship between phosphorus and cyanobacterial blooms. It contributes to the available literature on the behavior of P in hypertrophic lakes. The distribution of P-fractions in Lake Dianchi was not uniform from northwest to south, but was closely related to the trophic status of the whole lake. The concentrations of total phosphorus, labile P (NH₄Cl-P), Organic P (NaOH-NRP) and loss on ignition in suspended matter were positively correlated with the strength of cyanobacterial blooms. Total phosphorus in suspended matter was relatively stable for almost half an year and closely related to Chl. a concentration. The main content of organic phosphorus is in the cyanobacterial blooms. The concentrations of phosphorus bound to metal oxides and carbonates (NaOH-SRP and HCl-P) in sediment were similar to NaOH-SRP and HCl-P in the corresponding suspended matter. The latter two forms of P in suspended matter were not affected by cyanobacterial blooms, indicating that the inorganic phosphorus is derived from the sediment after resuspension from the sediment due to wind and wave action. The contribution of the different P-fractions to TP in sediment and in suspended matter indicates that NH₄Cl-P in the suspended matter is an important buffer for maintaining dissolved phosphorus in water.  相似文献   

Coastal pollution due to increasing nutrient flux in aquaculture sites     

C. P. C. David  Y. Y. Sta. Maria  F. P. Siringan  J. M. Reotita  P. B. Zamora  C. L. Villanoy  E. Z. Sombrito  R. V. Azanza 《Environmental Geology》2009,58(2):447-454

The supply of nitrogen and phosphorus in coastal zones through time is reflected in the nutrients’ concentration in the sediment record. Five aquaculture sites in the Philippines were investigated in an effort to establish how long-term changes in land and coastal water use could have led to biogeochemical modifications affecting the coastal ecosystem. Samples from study sites show a narrow concentration range for nitrogen and did not reveal any significant trend through time. In contrast, phosphorus concentrations in most sites start at less than 20 ppm in sediments 30 years and older. The phosphorus value continuously increase in younger sediments, with each site having a different magnitude change as well as timing of when the major increase happened. The uppermost 10 cm, representing the last 15 years in sites with age control, typically show a 2- to 3-fold increase in P load values. Historical increase in nutrient load also coincides with harmful algal bloom events in each area; when effective P input exceeded 130 kg/km² per year. Lastly, the observed increase may be attributed to several factors including physical attributes of the area, urbanization of coastal zones, but most importantly in the proliferation of aquaculture activities.  相似文献