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Dissertations / Theses on the topic 'Marine plankton'
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1
Martin, Mark A. "The influence of seasonal and climatic environmental changes on plankton in the marine mixed layer /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/6788.
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Lo, Shiu-hong. "Antibacterial activity of some marine planktonic algae in Hong Kong /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19667152.
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Veloza, Adriana J. "Transfer of Essential Fatty Acids by Marine Plankton." W&M ScholarWorks, 2005. http://www.vims.edu/library/Theses/Veloza05.pdf.
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Rani, Raj. "Modelling plankton dynamics in the east coast of India." Thesis, IIT Delhi, 2015. http://localhost:8080/xmlui/handle/12345678/6668.
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Wilson, William Hector. "Characterisation of viruses infecting marine phytoplankton." Thesis, University of Warwick, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283512.
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Chan, Lai-chun. "The ecology of marine plankton in Tai Tam Bay, Hong Kong, with special reference to barnacle (arthropoda : cirripedia) larvae /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14709089.
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Shaw, Stephanie Lyn 1973. "The production of non-methane hydrocarbons by marine plankton." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8255.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.Includes bibliographical references (p. 118-134).
The oceans are a small source of non-methane hydrocarbons (NMHC), a suite of volatile organics whose chemical destruction mechanism by reaction with hydroxyl radical can significantly affect the oxidation capacity of the atmosphere. Little is known about the water column cycling processes that constrain this source; previous work has established a photochemical source for many alkenes, and a phytoplanktonic source for isoprene. The focus of this thesis was to gain further insight on marine microbiological cycling of NMHC. This included investigations on two main themes. The first was the effect of different physiological conditions on phytoplanktonic isoprene production. A variety of phytoplankton were examined for the ability to produce isoprene. All were found to have constant isoprene production rates per cell during exponential growth, with decreasing rates as the populations senesced. A positive allometric relationship between isoprene production rate and cell volume was found; highest production rates were found for the largest cell tested, Emiliania huxleyi, and lowest rates for Prochlorococcus, the smallest. Isoprene production in Prochlorococcus was found to be a function of light intensity and temperature, with patterns similar to the relationships between growth rate of this species and these environmental parameters. The second theme investigated was the effect that heterotrophic marine plankton might have on NMHC cycling. We detected no clear production or consumption of any NMHC, except isoprene, from any of the phytoplankton or other organisms tested.
(cont.) The heterotrophic bacteria examined had no detectable effect on isoprene production per Prochlorococcus cell in a dual-species culture, but a temporary production of isoprene was detected from bacterial cultures grown in organically-enriched media. Nanoflagellate grazing by Cafeteria roenbergensis on Prochlorococcus had no detectable effect on NMHC cycling except to control the total phytoplankton counts, and thus total isoprene production. Besides controlling phytoplankton counts, phage lysis of Prochlorococcus had no detectable effect on NMHC cycling except to decrease isoprene production per Prochlorococcus cell during the latent period of infection. Any other effect these particular organisms may have on NMHC cycling likely involves other processes, such as photochemistry.
by Stephanie Lyn Shaw.
Ph.D.
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Anning, Tracy. "The expression of photosynthetic genes in natural populations of marine phytoplankton." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307079.
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Zhang, Rui. "Bacterioplankton in Hong Kong waters : diversity, dynamics, and mortality /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?BIOL%202007%20ZHANGR.
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Kunz, Thomas J. Diehl Sebastian. "Effects of mixing depth, turbulent diffusion, and nutrient enrichment on enclosed marine plankton communities." Connect to this title online, 2005. http://edoc.ub.uni-muenchen.de/archive/00004539/.
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Thesis (Ph. D.)--Ludwig-Maximilians-Universität München, 2005..Title from PDF title page (viewed on May 13, 2006). Includes three articles co-authored with Sebastian Diehl. Vita. Includes bibliographical references.
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Haskell, Andrew Glenn Edward. "Modeling plankton community structure under environmental forcing on the southeastern U.S. contintental shelf." [Norfolk, VA. : Center for Coastal Physical Oceanography], 1997. http://catalog.hathitrust.org/api/volumes/oclc/39263483.html.
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Vaga, Ralph M. "Experimental studies on trophic interactions in the plankton /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487264603217449.
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Johnson, Kevin Brett. "Predation on planktonic marine invertebrate larvae." Thesis, Thesis (Ph. D.)--University of Oregon, 1998, 1998. http://hdl.handle.net/1794/10086.
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Lee, Nga-wing Christine. "The ecology of planktonic copepods and hyperbenthic communities in the Cape d'Aguilar Marine Reserve, Hong Kong." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25212199.
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Christian, James Robert. "Modelling studies on a marine plankton community : biological, temporal and spatial structure." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27859.
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The SELECT model (Frost, 1982) is analyzed, criticized, and extended to embrace new information about the feeding behaviour of copepods and the structure of the planktonic food web in a series of alternative models. Diel variations in photosynthesis, grazing, and predation on copepods (temporal structure) and patchiness of zooplankton and their predators (spatial structure) are modelled in other variants. It is observed that the vertical, temporal, and (horizontal) spatial structure of the planktonic ecosystem are important components of ecosystem models that can not safely be ignored. It is further observed that a convincing mechanism for the termination of diatom blooms is lacking and should be a subject of intensive research, and that the status of chlorophyll-containing microflagellates as phototrophs is questionable and should be reconsidered.Science, Faculty of
Zoology, Department of
Graduate
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Daniels, Robert M. "Inverse Model Analysis of Plankton Food Webs in the North Atlantic and Western Antarctic Peninsula." W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539617808.
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Katechakis, Alexis. "Selected interactions between phytoplankton, zooplankton and the microbial food web: Microcosm experiments in marine and limnic habitats." Diss., Connect to this title online, 2006. http://edoc.ub.uni-muenchen.de/archive/00005047/.
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Thesis (doctoral)--Ludwig-Maximilians-Universität München, 2006.Title from PDF t.p. (viewed on May 14, 2006). Includes reprints of papers co-authored with others. Vita. Includes bibliographical references.
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Penczykowski, Rachel M. "Interactions between ecosystems and disease in the plankton of freshwater lakes." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50368.
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I investigated effects of environmental change on disease, and effects of disease on ecosystems, using a freshwater zooplankton host and its fungal parasite. This research involved lake surveys, manipulative experiments, and mathematical models. My results indicate that ecosystem characteristics such as habitat structure, nutrient availability, and quality of a host’s resources (here, phytoplankton) can affect the spread of disease. For example, a survey of epidemics in lakes revealed direct and indirect links between habitat structure and epidemic size, where indirect connections were mediated by non-host species. Then, in a mesocosm experiment in a lake, manipulations of habitat structure and nutrient availability interactively affected the spread of disease, and nutrient enrichment increased densities of infected hosts. In a separate laboratory experiment, poor quality resources were shown to decrease parasite transmission rate by altering host foraging behavior. My experimental results also suggest that disease can affect ecosystems through effects on host densities and host traits. In the mesocosm experiment, the parasite indirectly increased abundance of algal resources by decreasing densities of the zooplankton host. Disease in the experimental zooplankton populations also impacted nutrient stoichiometry of algae, which could entail a parasite-mediated shift in food quality for grazers such as the host. Additionally, I showed that infection dramatically reduces host feeding rate, and used a dynamic epidemiological model to illustrate how this parasite-mediated trait change could affect densities of resources and hosts, as well as the spread of disease. I discuss the implications of these ecosystem–disease interactions in light of ongoing changes to habitat and nutrient regimes in freshwater ecosystems.
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Painting, Suzanne Jane. "Bacterioplankton dynamics in the Southern Benguela upwelling region." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/23358.
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The role of heterotrophic bacteria in the carbon and nitrogen flux of the pelagic food web was investigated during laboratory and field-based studies of the temporal development of the planktonic community after upwelling. Bacterial community structure, activity and production were closely coupled to the upwelling cycle and to the dynamics of the phytoplankton community. The initial bacterial population (<l x 10⁶ cells ml⁻¹, 20 to 40 μg C l⁻¹) was metabolically dormant. Increased availability of phytosynthetically produced dissolved organic carbon (PDOC) stimulated bacterial growth (0.016 h⁻¹) and abundance (8 to 10 x 10⁶ cells ml⁻¹, 140 to 200 μg C l⁻¹). Rapid successions in the dominant plateable strains were attributed to substrate preferences and substrate availability. Significant correlations of bacterial biomass with total standing stocks of phytoplankton and particulate carbon provided evidence of close coupling between bacteria and PDOC, and between bacteria and recalcitrant substrates available during phytoplankton decay. These relationships were best described by power functions, suggesting that bacterial biomass was relatively reduced at high levels by predation. A microcosm study indicated that zooflagellate predation could control bacterial biomass. Low net growth yields (34 to 36%) of flagellates suggested inefficient transfer of carbon to higher trophic levels, but considerable nitrogen regeneration (ca 6 to 7 μg N mg dry weight⁻¹ h⁻¹). Thymidine-measured bacterial production (TTI, <0.1 to 1.25 mg C m⁻³ h⁻¹) was linearly related to phytoplankton growth. Non-uniform response of bacteria to added tracer substrates may result in underestimates of bacterial production by 2 to 34 times by TTI, particularly in deep or oligotrophic waters, or during phytoplankton decay. Close coupling of copepod (Calanoides carinatus) production to the upwelling cycle suggested co-existence of the microbial food web and the classical diatom-copepod food chain. Recently upwelled water was dominated by phytoplankton. Assuming that all phytoplankton carbon was available for utilisation, copepods and bacteria were calculated to consume approximately 12 and 22% of primary production respectively. As the bloom declined the planktonic community was increasingly dominated by bacteria, detritus and mesozooplankton. On average, copepods consumed 60% of primary production, while bacteria consumed 49%. Carbon consumption requirements of both bacteria and copepods were satisfied by resource partitioning and carbon cycling. Under food-limiting conditions herbivorous copepods may switch to omnivory, ingesting microzooplankton of the microbial food web, and stimulating enhanced remineralisation to further sustain primary production. A generic size-based simulation model of the dynamics of the plankton community indicated that bacteria and the microbial food web increase the overall productivity of the planktonic food web, and that heterotroph predation in the smaller size classes (<200 μm) is an important mechanism in nutrient recycling.
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Kunz, Thomas Joerg. "Effects of mixing depth, turbulent diffusion and nutrient enrichment on enclosed marine plankton communities." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-45397.
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Arenovski, Andrea Lynn. "The distribution, abundance and ecology of mixotrophic algae in marine and freshwater plankton communities." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/33523.
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Hjorth, Morten. "Responses of marine plankton to pollutant stress : integrated community studies of structure and function." [Copenhagen] : Danish Ministry of the Environment, National Environmental Research Institute, 2005. http://www2.dmu.dk/1_viden/2_Publikationer/3_Ovrige/rapporter/phd_moh.pdf.
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Matuszewski, Damian Janusz. "Computer vision for continuous plankton monitoring." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-24042014-150825/.
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Plankton microorganisms constitute the base of the marine food web and play a great role in global atmospheric carbon dioxide drawdown. Moreover, being very sensitive to any environmental changes they allow noticing (and potentially counteracting) them faster than with any other means. As such they not only influence the fishery industry but are also frequently used to analyze changes in exploited coastal areas and the influence of these interferences on local environment and climate. As a consequence, there is a strong need for highly efficient systems allowing long time and large volume observation of plankton communities. This would provide us with better understanding of plankton role on global climate as well as help maintain the fragile environmental equilibrium. The adopted sensors typically provide huge amounts of data that must be processed efficiently without the need for intensive manual work of specialists. A new system for general purpose particle analysis in large volumes is presented. It has been designed and optimized for the continuous plankton monitoring problem; however, it can be easily applied as a versatile moving fluids analysis tool or in any other application in which targets to be detected and identified move in a unidirectional flux. The proposed system is composed of three stages: data acquisition, targets detection and their identification. Dedicated optical hardware is used to record images of small particles immersed in the water flux. Targets detection is performed using a Visual Rhythm-based method which greatly accelerates the processing time and allows higher volume throughput. The proposed method detects, counts and measures organisms present in water flux passing in front of the camera. Moreover, the developed software allows saving cropped plankton images which not only greatly reduces required storage space but also constitutes the input for their automatic identification. In order to assure maximal performance (up to 720 MB/s) the algorithm was implemented using CUDA for GPGPU. The method was tested on a large dataset and compared with alternative frame-by-frame approach. The obtained plankton images were used to build a classifier that is applied to automatically identify organisms in plankton analysis experiments. For this purpose a dedicated feature extracting software was developed. Various subsets of the 55 shape characteristics were tested with different off-the-shelf learning models. The best accuracy of approximately 92% was obtained with Support Vector Machines. This result is comparable to the average expert manual identification performance. This work was developed under joint supervision with Professor Rubens Lopes (IO-USP).Microorganismos planctônicos constituem a base da cadeia alimentar marinha e desempenham um grande papel na redução do dióxido de carbono na atmosfera. Além disso, são muito sensíveis a alterações ambientais e permitem perceber (e potencialmente neutralizar) as mesmas mais rapidamente do que em qualquer outro meio. Como tal, não só influenciam a indústria da pesca, mas também são frequentemente utilizados para analisar as mudanças nas zonas costeiras exploradas e a influência destas interferências no ambiente e clima locais. Como consequência, existe uma forte necessidade de desenvolver sistemas altamente eficientes, que permitam observar comunidades planctônicas em grandes escalas de tempo e volume. Isso nos fornece uma melhor compreensão do papel do plâncton no clima global, bem como ajuda a manter o equilíbrio do frágil meio ambiente. Os sensores utilizados normalmente fornecem grandes quantidades de dados que devem ser processados de forma eficiente sem a necessidade do trabalho manual intensivo de especialistas. Um novo sistema de monitoramento de plâncton em grandes volumes é apresentado. Foi desenvolvido e otimizado para o monitoramento contínuo de plâncton; no entanto, pode ser aplicado como uma ferramenta versátil para a análise de fluídos em movimento ou em qualquer aplicação que visa detectar e identificar movimento em fluxo unidirecional. O sistema proposto é composto de três estágios: aquisição de dados, detecção de alvos e suas identificações. O equipamento óptico é utilizado para gravar imagens de pequenas particulas imersas no fluxo de água. A detecção de alvos é realizada pelo método baseado no Ritmo Visual, que acelera significativamente o tempo de processamento e permite um maior fluxo de volume. O método proposto detecta, conta e mede organismos presentes na passagem do fluxo de água em frente ao sensor da câmera. Além disso, o software desenvolvido permite salvar imagens segmentadas de plâncton, que não só reduz consideravelmente o espaço de armazenamento necessário, mas também constitui a entrada para a sua identificação automática. Para garantir o desempenho máximo de até 720 MB/s, o algoritmo foi implementado utilizando CUDA para GPGPU. O método foi testado em um grande conjunto de dados e comparado com a abordagem alternativa de quadro-a-quadro. As imagens obtidas foram utilizadas para construir um classificador que é aplicado na identificação automática de organismos em experimentos de análise de plâncton. Por este motivo desenvolveu-se um software para extração de características. Diversos subconjuntos das 55 características foram testados através de modelos de aprendizagem disponíveis. A melhor exatidão de aproximadamente 92% foi obtida através da máquina de vetores de suporte. Este resultado é comparável à identificação manual média realizada por especialistas. Este trabalho foi desenvolvido sob a co-orientacao do Professor Rubens Lopes (IO-USP).
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Pudota, Jayaprabandh. "Seasonal Variations in Biofouling and Plankton Community Connected to a Large Scale Salmon Farm." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12792.
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Biofouling is the one of the main problems in marine finfish aquaculture. Biofouling occludes the nets and incurs major costs to fish farmers in the form of copper containing anti fouling paints used on the net surfaces, cleaning and changing of nets. Copper containing anti fouling paints is the major protective method in use by the fish farmers, but given the toxicity of the copper towards the marine invertebrates and its ability to accumulate in the food chain, it may face a ban in marine aquaculture. So, there is a need to develop better anti fouling methods which will be as effective as copper, have least impact on the environment and cost effective to use. To design these, better understanding of the process of biofouling is needed. There is little data available about the biofouling in marine aquaculture.In this regard, I studied biofouling in a marine cage aquaculture farm (ACE/Tristeinen), located in mid-Norwegian coastal waters. In this study, knot less nylon net panels and Micanti net panels were used to compare different aspects of biofouling and to test the effectiveness of the Micanti nets. Zooplankton samples were collected and analyzed with a focus on the larval stages of the fouling organisms, to relate the plakntonic stages of the foulers in the zooplankton sample to the foulers present on the net panels. Sea lice larval stages presence in the zooplankton samples was also detected to study the movement of sea lice larval stages.Analysis of the net panels and zooplankton samples together showed a trend between the larvae of foulers found in the zooplankton samples and foulers present on the net panels. On net panels hydroids, mussels, algae, amphipods and nudibranchs accounted for the major proportion of the fouling. On nylon net panels hydroids were more compared to mussels and on Micanti net panels mussels were more compared to hydroids. Nets occlusion and net fouling wet weight was slightly less on the micanti net panels compared to nylon net panels. Few sea lice, Lepeophtheirus salmonis larval stages were found in the zooplankton samples. Micanti did not work as expected, as it having problems with strength, length and density of the fibers flocked on the net. Improving these would help to improve the functionality of the Micanti nets as a better non-toxic antifouling technology.
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Amundsson, Katharina. "Control of marine plankton respiration : High temperature sensitivity at low temperatures influenced by substrate availability." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-128624.
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Temperature dependence of marine plankton respiration is an important factor in understanding the function and changes in the ecosystem of the ocean. The aim of this study is to test the temperature sensitivity (Q10) of plankton respiration. The oxygen optode method was used to measure plankton respiration. Natural water samples from the Baltic Sea was incubated at short (in situ +1, +2, +3°C) and long (in situ +5, +10, +20°C) temperature intervals with influence of dissolved organic matter (DOC). The Arrhenius equation and Q10-model was used to determine the temperature dependence (Q10) of respiration at different temperatures. There was a significant difference in Q10 between short temperature intervals at low temperatures (p=0,008) and long temperature intervals at higher temperatures. There was no significant difference between long and short temperature intervals when DOC was added (p=0,094). A significant effect could be seen with the DOC enrichment at low temperatures, where the Q10-values became significantly lower (p=0,002) after DOC addition. This effect could, however, not be seen at higher temperatures (p=0,117). Together with results from earlier studies it was concluded that the difference in temperature depends on the actual temperature and not the length of the interval. Lowered temperature dependence at raised DOC concentration, was the opposite of what was expected. The results suggest that the importance of temperature for CO2 emissions and development of hypoxia in the sea may have been underestimated.
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Cavender-Bares, Kent Keller 1966. "Size distributions, population dynamics, and single-cell properties of marine plankton in diverse nutrient environments." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/34338.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.Includes bibliographical references.
The goal of this thesis is to study the relationship between the community structure of marine microorganisms and nutrient availability. To this end, size spectra of microbes were studied over a range of nutrient regimes, both natural and manipulated. Three transects in the Atlantic provided a natural range of nutrient environments, especially because they captured seasonal variations. The transects encompassed Sargasso Sea, Gulf Stream, and coastal waters, during winter, spring, and summer. Nutrient regimes ranged from surface waters of the Sargasso Sea during stratified periods (low-nutrient), to deeply mixed waters in all three regions of the transects during winter and spring (high-nutrient). Complementing natural variations in nutrients, two experiments were used to study the effects of enrichment on size structure. An in situ iron-enrichment experiment conducted in the equatorial Pacific (IronEx II) provided a unique opportunity to monitor changes in community structure following increased nutrient availability. In a second experiment in the Sargasso Sea, enrichments with nitrogen and phosphorus were conducted in bottles, because one or both are commonly thought to be limiting in this region. In order to carry out the goal of this thesis, which depended on the use of flow cytometry to characterize bacterio-, pico-, ultra-, and nanophytoplankton, advancements were made in methods for enumerating a wide range of cell sizes and for estimating cell size from forward angle light scatter. In addition, because ambient concentrations of inorganic nitrogen and phosphorus are exceedingly low (<10nM) in the Atlantic, especially during stratified periods, low-level determinations of these nutrients were made to compliment the analyses of community structure. Size structure varied systematically, although not necessarily as a function of nutrient availability. Two parameters were explored: 1) spectral slope, which indicates the relative contribution of large and small cells to total biomass, and 2) spectral shape, or adherence of the spectra to relationships explained by a power law. The relative ranking of the slopes from specific regions of the transects remained constant throughout different seasons. Shapes ranged from discontinuous to those which adhered to a power law. It is hypothesized that only microbial systems with abundant nutrient inputs and, perhaps, reduced grazing pressure, have smooth spectra whose shapes conform to power laws.
by Kent Keller Cavender-Bares.
Ph.D.
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Kramer, Kurt A. "System for Identifying Plankton from the SIPPER Instrument Platform." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3646.
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Plankton imaging systems such as SIPPER produce a large quantity of data in the form of plankton images from a variety of classes. A system known as PICES was developed to quickly extract, classify and manage the millions of images produced from a single one-week research cruise. A new fast technique for parameter tuning and feature selection for Support Vector Machines using Wrappers was created. This technique allows for faster feature selection, while at the same time maintaining and sometimes improving classification accuracy. It also gives the user greater flexibility in the management of class contents in existing training libraries.
Support vector machines are binary classifiers that can implement multi-class classifiers by creating a classifier for each possible combination of classes or for each class using a one class versus all strategy. Feature selection searches for a single set of features to be used by each of the binary classifiers. This ignores the fact that features that may be good discriminators for two particular classes might not do well for other class combinations. As a result, the feature selection process may not include these features in the common set to be used by all support vector machines. It is shown through experimentation that by selecting features for each binary class combination, overall classification accuracy can be improved and the time required for training a multi-class support vector machine can be reduced. Another benefit of this approach is that significantly less time is required for feature selection when additional classes are added to the training data. This is because the features selected for the existing class combinations are still valid, so that feature selection only needs to be run for the new combination added.
This work resulted in a system called PICES, a GUI based user friendly system, which aids in the classification management of over 55 million images of plankton split amongst 180 classes. PICES embodies an improved means of performing Wrapper based feature selection that creates classifiers that train faster and are just as accurate and sometimes more accurate, while reducing the feature selection time.
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Chan, Lai-chun, and 陳麗珍. "The ecology of marine plankton in Tai Tam Bay, Hong Kong, with specialreference to barnacle (arthropoda : cirripedia) larvae." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31234112.
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Lo, Shiu-hong, and 羅兆康. "Antibacterial activity of some marine planktonic algae in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B3121339X.
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李雅詠 and Nga-wing Christine Lee. "The ecology of planktonic copepods and hyperbenthic communities in theCape d'Aguilar Marine Reserve, Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B43895062.
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Hackett, Christine Anne. "Mathematical and statistical modelling of marine plankton in the vicinity of the Western Irish sea front." Thesis, Cardiff Metropolitan University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314595.
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Liu, Zonghua. "A shape-based image classification and identification system for digital holograms of marine particles and plankton." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238473.
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The objective of this project is to develop a shape-based image analysis system, which allows classification and identification of holographic images of marine particles and plankton recorded by an underwater digital holographic camera. In order to achieve this goal, the first step is to extract shape regions of objects from images and to describe the regions by polygonal boundaries. After extraction of the polygonal boundary curve of an object, affine-invariant curve normalisation is implemented on the curve to reduce the influence of object shape deformations on object identification and classification. Six numeric features are then selected to describe shape properties of an object. Before these six shape features are used as a numeric interpretation of an object for image analysis, some processing of them is necessary, consisting of selecting the number of items in each feature and rescaling the selected feature vectors. Afterwards, Gaussian rescaling is adopted to rescale the feature data. Lastly, a shape-based image classification and identification system is built. The system contains two components: semi-automatic image classification (imCLASS) and automatic image identification (imIDENT). In imCLASS, an image retrieval method based on the support vector machine with a feedback mechanism has been developed. The function of imCLASS is to classify given images into different folders with the corresponding labels from the user. These labelled folders can be used to train the artificial neural network in imIDENT. A set of analyses of effects of the proposed methods in the process chain on image analysis are carried out. The whole performance of the system for classifying and identifying marine particles and plankton is also evaluated in terms of the time-cost and accuracy performance. In the end, some main conclusions are listed. The areas of weakness of the system are also highlighted for future work.
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Moloney, Coleen Lyn. "A size-based model of carbon and nitrogen flows in plankton communities." Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/22132.
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Bibliography: pages 163-183.A generic, size-based simulation model is developed to investigate the dynamics of carbon and nitrogen flows in plankton communities. All parameters in the model are determined by body size using empirically-determined relationships calculated from published data. The model is robust with respect to most parameters and assumptions. Because the model is based on general ecological principles, it can be used to simulate microplankton community interactions in any planktonic ecosystem. Two coastal ecosystems from the southern Benguela region in South Africa are simulated; one typical of the relatively stable surface waters on the Agulhas Bank and one typical of upwelling plumes, usually found off the west coast of South Africa. Simulated communities compare well with field observations in terms of standing stocks and size composition, and simulation results indicate that the small-scale structure of the two ecosystems and the processes occurring within them are relatively well understood. Consequently, the dynamic functioning of the two systems is investigated at the ecosystem level, using the simulation results. Hypothetical carbon flow networks are constructed, and the average importance of different flow pathways at different times is assessed. In both ecosystems, the vast majority of carbon flows pass through short, efficient-transfer pathways, although longer pathways are potentially possible. Simulation analyses are extended from coastal to oceanic food webs, and the model results are consistent with the hypothesis that oceanic phytoplankton have rapid rates of primary production. At-sea sampling of a phytoplankton bloom is mimicked by "sampling" from simulation output, and interpretation of the data using standard techniques is compared with the model output. The dangers of extrapolating from snapshot measurements is highlighted, and the experiment emphasizes the importance of size-fractionated sampling of phytoplankton. A hypothetical pelagic food web is described, consisting of at least five different trophic pathways from phytoplankton to pelagic fish. It is suggested that coastal waters probably have all the different pathways, and the relative importance and efficiency of the different pathways will determine the total fish production in an ecosystem.
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Eloire, Damien. "Spatial and temporal patterns of plankton in European coastal waters : analysis and comparison of zooplankton time series." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20059.
Full textAbstract:
Le changement climatique est incontestable et affecte les océans. L'observation à long terme d'indicateurs comme le plancton peut permettre l'étude de ces changements. Le suivi du plancton dans les eaux côtières d'Europe représente une source de données importante actuellement sous-exploitée et sur laquelle cette étude est basée. Des outils analytiques ont d'abord été conçus pour résoudre des divergences taxonomiques entre les données et pour réaliser l'analyse temporelle. L'étude du plancton à L4 de 1998 à 2007 révèle de profonds changements dans la composition phytoplanctonique des blooms de printemps et d'automne, et des variations à long terme dans l'abondance des taxa dominants du zooplancton. Le phytoplancton gouverne la succession saisonnière des larves méroplanctoniques. Les changements de température de surface et de vent contrôlent les variations temporelles des communautés planctoniques. Les variations spatio-temporelles du zooplancton ont été comparées à 4 sites de 1998 à 2007 : Ston (Mer du Nord), L4 (Manche), MC (Mer Tyrrhénienne ), et C1 (Mer Adriatique). La structure des communautés est globalement stable, la saisonnalité étant la principale source de variabilité à long terme. La chlorophylle a et le vent expliquent les variations de la communauté zooplanctonique à Ston et L4 alors que c'est la température à MC et C1. Cette étude confirme l'extrême adaptabilité des communautés zooplanctoniques à un environnement variable. Elle souligne l'importance de facteurs tels que taxonomie et échelle temporelle pour l'analyse de séries, et la nécessité de maintenir les séries à long terme pour le suivi de futurs changements dans le contexte du changement climatiqueClimate change is unequivocal and dramatic changes are under way in the world's oceans. Long-term observations of indicators such as plankton can provide a better understanding of these changes. Considerable efforts have been made to monitor plankton in European coastal waters and have produced a large amount of datasets yet to be fully exploited. Analytic tools were first developed to solve taxonomic discrepancies in datasets and for temporal analyses. Time series analysis of plankton at L4 from 1988 to 2007 reveals profound changes in the composition of the spring and autumn phytoplankton blooms, and long-term variations in abundance of the dominant zooplankton taxa. Phytoplankton is driving the seasonal succession of meroplanktonic larvae. Changes in sea surface temperature and wind conditions control temporal patterns of plankton communities. Spatio-temporal patterns of zooplankton are compared at 4 sites: Ston (northern North Sea), L4 (wes tern English Channel), MC (Tyrrhenian Sea), and C1 (Adriatic Sea) from 1998 to 2007. The communities structure is on average stable and seasonal variations are the main source of long-term variability. Chlorophyll a and wind are responsible for the community patterns observed at Ston and L4 whereas temperature is the main driver at MC and C1. This study supports evidences of the extreme flexibility of zooplankton communities in adjusting to a variable environment. We highlighted the importance of factors such as taxonomy and temporal scale on time series analysis, and the necessity of maintaining long-term series to monitor future changes in the context of climate change
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Arp, Jennifer Rebecca. "Quantification of marine archaea in the Cape Fear River Estuary in southeastern North Carolina using fluorescence in situ hybridization /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/arpj/jenniferarp.html.
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Braker, John M. "The Impact of Variability in Coastal Circulation on Plankton Distributions Along the Continental Shelf of Southeast Florida." NSUWorks, 1995. http://nsuworks.nova.edu/occ_stuetd/346.
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Time series of zooplankton concentrations and current velocities were collected with a bottom mounted (190 m) 307.2 kHz acoustic Doppler current profiler (ADCP) at the shelf break off Fort Lauderdale, Florida. Simultaneously, time series of temperature and salinity were collected with a moored CTD in the Port Everglades estuary approximately 4 km inshore of the ADCP mooring. Software was developed to extract acoustic volume scattering strength data (Vs) from the ADCP data stream. Vs is a relative measure of zooplankton concentration. In addition, eastward velocity and northward velocity data were collected from the ADCP. Data were recorded in two minute averages, with additional processing yielding hourly averages. Acoustic volume scattering strength and current velocity records from 176, 136, 95, and 56 m deep were isolated during post-processing for spectral analysis. The acoustic estimate of zooplankton concentration was found to be coherent with current velocity (both north and east components) at frequencies corresponding to the scales of Gulf Stream meanders (2-10 days per cycle) and diurnal and semi-diurnal tidal variability (24 and 12 hours per cycle, respectively). Estuarine salinity variations were also coherent with variability in circulation at the shelf break at the energetic periods of 24, 12, 8 and 6 hours per cycle. Estuarine salinity varied inversely with the distance of the Gulf Stream front from shore (0.5 - 6 week observation interval). Apparently, low frequency variability in the salinity of estuarine water is also associated with variability in the position of the Gulf Stream. It would appear that variability of Gulf Stream position and flow influences the cross-shelf transport of planktonic organisms, such as fish larvae, at a variety of temporal scales and thereby links offshore and estuarine ecosystems off southeast Florida.
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Sauterey, Boris. "How do ecological and evolutionary dynamics interact together and with the environment to shape the structure of oceanic plankton communities? : A modelling approach." Paris 7, 2014. http://www.theses.fr/2014PA077259.
Full textAbstract:
Les modèles récents de circulation océanique intègrent l'écologie des phytoplanctons d'une manière relativement détaillée, prenant en compte divers types fonctionnels de planctons, voir la variabilité spécifique (Follows et al. 2007). Ces modèles ont montré l'importance de l'écologie fonctionnelle dans la compréhension des cycles biogéochimiques et des potentielles rétroactions entre écosystèmes marins et changement globaux (Cermerio and Falkowski 2009). Une question reste cependant ouverte : l'évolution des planctons accélère-t-elle ou atténue-t-elle l'impact du changement climatique sur le cycle du carbone ? Cette question va au delà du cadre de cette thèse, mais ce travail est un premier pas dans cette direction. Avant de pouvoir répondre, une problématique plus fondamentale doit être abordée : comment l'évolution et l'écologie interagissent, façonnant ainsi les communautés écologiques vivant dans l'écosystème complexe et hautement forcé dans le temps, que sont les océans ? Une autre question, plus appliquée est : est il possible de décrire de manière fiable les réseaux trophiques complexes dans un tel contexte, sans tenir compte des dynamiques évolutives ? Et donc, à quel point les modèles actuels basés sur le paradigme "everything is everywhere, but the environment selects" sont ils fiables ? Pour répondre à ces questions, le premier objectif spécifique de cet thèse est de modifier un modèle de circulation océanique existant (le MITgcm Follows et al. 2007; Ward et al. 2012, 2013) afin d'y intégrer l'adaptation en trait des phytoplanctonsRecent global ocean circulation models integrate phytoplankton ecology in a relatively detailed manner, accounting for a variety of plankton functional types or even species-level variability (Follows et al. 2007). Such models have demonstrated the importance of ecological detail (in terms of functional composition) for global biogeochemical cycles and possible positive feedbacks between marine ecosystems and climate change (Cermeho and Falkowski 2009). An open question today is : does phytoplankton (and zooplankton) evolution accelerate or mitigate the impact of climate change on the global carbon cycle ? Answering this question is beyond the scope of this thesis, and the work in this thesis should be seen as a first step in this direction. Before being able to answer to the above question, a more fundamental topic needs to be addressed: how do evolution and ecology interact to shape the ecological communities living in the highly complex and temporally forced environment that is the ocean? And a derived, more applied question is: can we obtain a plausible description of the complex food webs in such contexts, without accounting for evolution? Otherwise stated, how reliable is the currently used methodology for simulating the emergence of complex food webs through community assembly, based on the non-adaptive paradigm of "everything is everywhere, but the environment selects"? In order to answer these questions, the more specific objective of my thesis is to extend an existing global circulation model (the MITgcm, Follows et al. 2007; Ward et al. 2012, 2013) in order to allow for the simulation of adaptation of phytoplankton traits
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Toledo, Gerardo V. "Genetic diversity of the unicellular cyanobacteria Synechococcus in the California Current /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3025941.
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Huggett, Jenny A. "The effect of chlorine, heat and physical stress on entrained plankton at Koeberg Nuclear Power Station." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/17079.
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Bibliography: pages 112-138.The large volume of seawater used for cooling at Koeberg Nuclear Power Station contains many planktonic organisms which are exposed to heat, chlorine and physical stress during their passage through the system. Phytoplankton biomass, measured as chlorophyll a, was reduced by an average of 55.32% due to entrainment, and productivity was decreased by 38.30% on average, mainly due to chlorination. Zooplankton mortality averaged 22.34% for all species and 30.52% for copepods, the dominant group. The copepod Paracartia africana was used in laboratory experiments designed to simulate entrainment. Latent mortality was monitored up to 60 hours after a 30-minute application of stress factors (physical stress was not simulated), and approximately 75% of the total mortality occurred within the 30-minute period. Male Paracartia experienced higher mortalities than females. Extrapolation of these results predicts an overall entrainment mortality (including latent mortality) of 40% for copepods and 29.04% for total zooplankton, although the latter cannot be substantiated. Plankton entrainment at Koeberg was not considered to be overly detrimental to the marine environment because of the very localised area affected, rapid dispersion of heat and chlorine, rapid regeneration times of phytoplankton and some zooplankton, low abundance of commercially important species and potential recruitment from the surrounding productive Benguela upwelling region.
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Du, Qingling. "Relationship of plankton and marine snow to hydrography and currents on the south portion of Georges Bank during June 1997." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/31192.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Biology, 2005.Includes bibliographical references (leaves 76-79).
A key question in biological oceanography is how plankton populations maintain themselves in regions of favorable growth and survival in the face of horizontal transport by ocean currents. Plankton are thought to be retained on the highly productive Georges Bank by the clockwise flow, which intensifies with vernal warming. The extent to which plankton are transported off the bank to the southwest or transported northward and retained on the bank remains poorly understood. This thesis examined the relationship between plankton and physical properties in the southwest corner of the bank, the retention-loss region (RLR). Analysis of field data (Video Plankton Recorder, Acoustic Doppler Current Profiler, and satellite-tracked drifters) and modeling results was performed to quantify the relationships between plankton, hydrography, and currents and the fluxes through the RLR. Temperature-salinity-plankton diagrams and factor analysis revealed that most plankton taxa had characteristic relationships to the hydrography, with the exception of copepods which were everywhere abundant. The flux of plankton during a complete tidal cycle and in the de-tided current data indicated this region was not retentive to plankton, since the bulk of the flow remained to the southwest, despite the presence of a vernally warmed surface layer. A Lagrangian particle trajectory model was used to further examine transport of plankton through the RLR during late spring /early summer (June) when vernal stratification was established. Passive particles were used, since no diel vertical migration by plankton was found in the data. The model revealed that the bulk of the plankton was carried out of the RLR through the southern and western boundaries.
(cont.) The modeling and data analysis show clearly that the plankton were lost from the bank to the southwest rather than being re-circulated to the north. These results have important implications for the plankton populations on Georges Bank and can be used in future modeling efforts that examine the factors controlling plankton populations in this region.
by Qingling Du.
S.M.
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Meng, Arnaud. "Étude de la symbiose dans le plancton marin par une approche transcriptome et méta-transcriptome." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066478/document.
Full textAbstract:
Les relations symbiotiques entre organismes sont essentielles pour l’évolution de la bio- diversité et le fonctionnement des écosystèmes. En milieu terrestre ou en milieu marin benthique les symbioses sont assez bien décrites. Si dans le plancton marin, les relations entre hôtes hétérotrophes et symbiontes photosynthétiques sont des phénomènes observés dès le 19ème siècle, les mécanismes fonctionnels qui régissent ces symbioses restent largement inconnus. C’est le cas de la symbiose entre certaines espèces de radiolaires et leurs symbiontes dinoflagellés. Il s’agit d’un modèle symbiotique, composé de deux unicellulaires eucaryotes, sur lequel je me suis concentré au cours de cette thèse. Ces deux organismes sont connus pour être largement répandus dans les océans et pour leur importance au sein des écosystèmes marins, et il est donc important de mieux caractériser ces symbioses afin d’approfondir nos connaissances de ces organismes. Grâce aux technologies de séquençage haut-débit il est désormais possible d’obtenir, pour ces organismes non cultivables mais isolés depuis l’environnement, une quantité sans précédent d’information génomique. Ces approches représentent une opportunité de décrypter les mécanismes à l’oeuvre dans ces interactions symbiotiques. Mon travail de thèse a combiné la création d’outils bioinformatiques dédiés à l’analyse de données de transcriptomique des holobiontes de radiolaires et dinoflagellés et l’étude de ce modèle de symbiose. Ce travail de doctorat contribue à une meilleure compréhension des mécanismes d’adaptation fonctionnelle et évolutive des organismes photosymbiotiques marinsSymbiotic associations between organisms are essentials in biodiversity evolution and ecosystems functioning. In terrestrial environments or in the benthic marine environment, the symbioses encountered are fairly well described and studied. In the marine plankton, photosymbioses are phenomena described and observed since the 19th century. However, if the actors of these associations begin to be identified, the fundamental functional mechanisms for the establishment and the maintenance of these symbioses remain largely unknown. This is particularly true for the symbiotic association between symbiotic radiolarians and their dinoflagellate photosymbionts, two unicellular eucaryotes, which I was interested in during this thesis. These two organisms are known to be widespread in the oceans and for their key role in marine ecosystems, and it is therefore important to characterize these symbiotic events in order to deepen our knowledge of these organisms. Thanks to high-throughput sequencing technologies it is now possible to obtain an unprecedented amount of data for these unicellular organisms that are not cultivable and need to be directly isolated from the environment. These new technologies represent a unique opportunity to better characterized the mechanisms involved in these intimate cellular interactions. My Ph.D. work has combined the implementation of bioinformatics protocols and tools dedicated to the assembly and analysis of RNA-seq data as well as to the study of holobiont transcriptomes of radiolarians and dinoflagellates. This thesis contributes to a better understanding of the mechanisms of functional and evolutionary adaptation of marine photosymbiotic organisms
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Maldonado, Elisa Marie. "Biological-physical interactions in marine plankton the effects of small-scale turbulence on grazing, growth, and swimming of sea urchin larvae /." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3386891.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed January 19, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Schultz, Cristina. "A modeling study of the marine biogeochemistry, plankton dynamics, and carbon cycle on the continental shelf off the West Antarctic Peninsula." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122331.
Full textAbstract:
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 189-202).
Over the past several decades, the West Antarctic Peninsula (WAP) has undergone physical and ecological changes at a rapid pace, with warming surface ocean and a sharp decrease in the duration of the sea ice season. The impact of these changes in the ocean chemistry and ecosystem are not fully understood and have been investigated by the Palmer-LTER since 1991. Given the data acquisition constraints imposed by weather conditions in this region, an ocean circulation, sea ice and biogeochemistry model was implemented to help fill the gaps in the dataset. The results with the present best case from the suite of sensitivity experiments indicate that the model is able to represent the seasonal and interannual variations observed in the circulation, water mass distribution and sea ice observed in the WAP, and has identified gaps in the observations that could guide improvement of the simulation of the regional biogeochemistry. Comparison of model results with data from the Palmer-LTER project suggests that the large spatial and temporal variability observed in the phytoplankton bloom in the WAP is influenced by variability in the glacial sources of dissolved iron. Seasonal progression of the phytoplankton bloom is well represented in the model, and values of vertically integrated net primary production (NPP) are largely consistent with observations. Although a bias towards lower surface dissolved inorganic carbon (DIC) and alkalinity was identified in the model results, interannual variability was similar to the observed in the Palmer-LTER cruise data.
by Cristina Schultz.
Ph. D.
Ph.D. Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution)
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Zablotski, Yury [Verfasser]. "Optimality and trait based approaches to sympatric speciation and sympatric co-evolution of predator and prey traits in marine plankton / Yury Zablotski." Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/105432820X/34.
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Meng, Arnaud. "Étude de la symbiose dans le plancton marin par une approche transcriptome et méta-transcriptome." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066478.
Full textAbstract:
Les relations symbiotiques entre organismes sont essentielles pour l’évolution de la bio- diversité et le fonctionnement des écosystèmes. En milieu terrestre ou en milieu marin benthique les symbioses sont assez bien décrites. Si dans le plancton marin, les relations entre hôtes hétérotrophes et symbiontes photosynthétiques sont des phénomènes observés dès le 19ème siècle, les mécanismes fonctionnels qui régissent ces symbioses restent largement inconnus. C’est le cas de la symbiose entre certaines espèces de radiolaires et leurs symbiontes dinoflagellés. Il s’agit d’un modèle symbiotique, composé de deux unicellulaires eucaryotes, sur lequel je me suis concentré au cours de cette thèse. Ces deux organismes sont connus pour être largement répandus dans les océans et pour leur importance au sein des écosystèmes marins, et il est donc important de mieux caractériser ces symbioses afin d’approfondir nos connaissances de ces organismes. Grâce aux technologies de séquençage haut-débit il est désormais possible d’obtenir, pour ces organismes non cultivables mais isolés depuis l’environnement, une quantité sans précédent d’information génomique. Ces approches représentent une opportunité de décrypter les mécanismes à l’oeuvre dans ces interactions symbiotiques. Mon travail de thèse a combiné la création d’outils bioinformatiques dédiés à l’analyse de données de transcriptomique des holobiontes de radiolaires et dinoflagellés et l’étude de ce modèle de symbiose. Ce travail de doctorat contribue à une meilleure compréhension des mécanismes d’adaptation fonctionnelle et évolutive des organismes photosymbiotiques marinsSymbiotic associations between organisms are essentials in biodiversity evolution and ecosystems functioning. In terrestrial environments or in the benthic marine environment, the symbioses encountered are fairly well described and studied. In the marine plankton, photosymbioses are phenomena described and observed since the 19th century. However, if the actors of these associations begin to be identified, the fundamental functional mechanisms for the establishment and the maintenance of these symbioses remain largely unknown. This is particularly true for the symbiotic association between symbiotic radiolarians and their dinoflagellate photosymbionts, two unicellular eucaryotes, which I was interested in during this thesis. These two organisms are known to be widespread in the oceans and for their key role in marine ecosystems, and it is therefore important to characterize these symbiotic events in order to deepen our knowledge of these organisms. Thanks to high-throughput sequencing technologies it is now possible to obtain an unprecedented amount of data for these unicellular organisms that are not cultivable and need to be directly isolated from the environment. These new technologies represent a unique opportunity to better characterized the mechanisms involved in these intimate cellular interactions. My Ph.D. work has combined the implementation of bioinformatics protocols and tools dedicated to the assembly and analysis of RNA-seq data as well as to the study of holobiont transcriptomes of radiolarians and dinoflagellates. This thesis contributes to a better understanding of the mechanisms of functional and evolutionary adaptation of marine photosymbiotic organisms
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Jones, Benjamin Thomas. "Trait-based modeling of larval dispersal in the Gulf of Maine." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112889.
Full textAbstract:
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 151-163).
Population connectivity is a fundamental process that governs the spatial and temporal dynamics of marine ecosystems. For many marine species, population connectivity is driven by dispersal during a planktonic larval phase. The ability to obtain accurate, affordable, and meaningful estimates of larval dispersal patterns is therefore a key aspect of understanding marine ecosystems. Although field observations provide insight into dispersal processes, they do not provide a comprehensive assessment. Individual-based models (IBMs) that couple ocean circulation and particle-tracking models provide a unique ability to examine larval dispersal patterns with high spatial and temporal resolution. Obtaining accurate results with IBMs requires simulating a sufficient number of particles, and the sequential Bayesian procedure presented in chapter 2 identifies when the number of particles is adequate to address predefined research objectives. In addition, this method optimizes the particle release locations to minimize the requisite number of particles. Even after applying this method, the computational expense of IBM studies is still large. The model in chapter 3 seeks to increase the affordability of IBM studies by transferring some of the calculations to graphics processing units. Chapter 4 describes three algorithms that assist in interpreting IBM output by identifying coherent geographic clusters from population connectivity data. The first two algorithms have existed for nearly a decade and recently been applied separately to marine ecology, and we provide a direct comparison of the results from each. Additionally, we develop and present a new algorithm that simultaneously considers multiple species. Finally, in chapter 5, we apply these tools and a trait-based modeling framework to assess which species traits are most likely to impact dispersal success and patterns in the Gulf of Maine. We conclude that the traits influencing spawning distributions and habitat requirements for settlement are most likely to influence dispersal.
by Benjamin Thomas Jones.
Ph. D.
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Henry, Nicolas. "Écologie moléculaire des symbioses eucaryotes des écosystèmes planctoniques de la zone photique des océans." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066181/document.
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Les symbioses ont un role majeur dans le fonctionnement et l'equilibre des ecosystemes. Dans les oceans, qui couvrent pres de 70 % de la surface de la planete, vivent une multitude d'organismes incapables de lutter contre les courants et la plupart sont microscopiques, il s'agit du plancton. Les organismes du plancton, comme ceux d'autres ecosystemes, entretiennent des symbioses, mais la nature et l'ampleur de ces interactions sont encore mal connues dans le plancton du fait la petite taille de ces organismes et de la difficulte d'echantillonnage des ecosystemes planctoniques, surtout dans les zones les plus eloignees des cotes. Les principaux objectifs de cette these sont de donner un apercu global de la place occupee par ces symbioses dans le plancton et de proposer des methodes originales permettant leur detection. Les travaux presentes dans ce manuscrit s'appuient sur l'analyse des donnees generees lors de l'expedition Tara Oceans (2009-2013) pendant laquelle 210 stations oceaniques ont ete echantillonnees a travers le monde. Ils concernent plus precisement le jeu de donnees environnemental obtenu grace au sequencage a haut debit (Illumina) de la region hypervariable V9 (130 nucleotides) de la sousunite 18S de l'ADN ribosomique des organismes eucaryotes (metabarcoding). Dans un premier temps, un etat des lieux de la diversite et de la structure des communautes du pico-nano-micro-mesoplancton (0,8-2000 μm) eucaryote de la zone photique des oceans temperes a tropicaux est realise. Il met en evidence la place importante occupee par les symbiotes au sein de ces communautes. Ensuite, l'etude de deux cas de symbiose (Blastodinium- Copepodes et Symbiodinium-Tiarina) montre les difficultes inherentes a la detection de couples symbiotiques a partir d’un jeu de donnees issue d'etudes par metabarcoding du plancton (flexibilite de la specificite des symbioses dans le plancton), mais aussi la possibilite de distinguer les differentes phases de vie des symbiotes (libres et symbiotiques) lorsque les echantillons etudies ont ete fractionnes. Enfin, un ensemble de methodes est propose afin d'ameliorer l'efficacite de la detection de symbioses dans le cadre d'etudes par reseau de cooccurrences des communautes planctoniques. L'analyse de la distribution des metabarcodes le long des fractions de taille (piconano- (0.8-5 μm), nano- (5-20 μm), micro- (20-180 μm), et meso-plancton (180-2000 μm)) permet de differencier ceux provenant d'organismes symbiotiques de ceux d'organismes libres, sans a priori. De plus la comparaison de l'abondance de groupes genetiques definis a differents niveaux de resolution permet de detecter des associations symbiotiques peu specifiques et d'apprecier leur niveau de specificiteThe oceans, which cover nearly 70 % of the earth's surface, is host to a myriad of mostly microscopic organisms that drift with the currents and are collectively called plankton. As in other ecosystems, symbioses play a major role in the functioning and equilibrium of the plankton. But the exact nature and strength of those symbiotic interactions are still poorly known, not only due to the small size of most planktonic organisms, but also because of the inherent difficulty of sampling planktonic ecosystems, especially in the high-seas. The main goals of this thesis are to give a global view of the importance of planktonic symbioses and to propose novel methods for their detection. The work presented in this manuscript is based on analyses of data generated during the Tara Oceans expedition (2009-2013), during which sea water was collected and size fractionated by filtration at 210 sampling locations distributed across the world's oceans. The data analyses presented herein mostly focus on an environmental metabarcoding dataset obtained from next-generation sequencing (Illumina) of the V9 hypervariable region (~130 nucleotides long) of the 18S small ribosomal subunit of eukaryotic organisms. We begin by assessing the diversity and structure of pico-, nano-, micro and meso-planktonic eukaryotic communities (0.8-2000 μm) in the photic zone of tropical to temperate sea regions. Then, we present two cases of symbioses (Blastodinium-Copepods and Symbiodinium-Tiarina) to illustrate both the difficulties encountered when trying to detect symbiotic relationships using metabarcoding data due to varying specificities of symbiotic relationships, but also the potential solutions offered by size-fractionated sampling to distinguish between the different stages of the life cycle of symbiotic organisms (free living and symbiotic stages). Finally, we propose a set of methods to improve the detection of symbioses by studying the co-occurrence of organisms in planktonic communities: we use the distribution of metabarcodes along size fractions ((piconano- (0.8-5 μm), nano- (5-20 μm), micro- (20-180 μm), and meso-plancton (180-2000 μm)) to distinguish likely free living organisms from those that have a symbiotic life style, and we compare the abundance of genetic groups constructed by clustering metabarcodes at different resolution levels, which allows us to detect interactions occurring above the species level and to evaluate their level of specificity
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Anschütz, Anna-Adriana. "Modelling mixoplankton functional types – examples from the cryptophyte- Mesodinium-Dinophysis complex." Doctoral thesis, Universite Libre de Bruxelles, 2021. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/325724.
Full textAbstract:
Mixoplankton are protist plankton that are capable of phototrophy and phagotrophy. These organismsare increasingly recognised not just as freaks of nature, but as a substantial part of marineplankton. Most existing plankton models still assume a strict dichotomy between phototrophsand heterotrophs. Few models consider mixoplanktonic activity as a synergism of the two trophicmodes. Many different mixoplankton functional types exist on a gradient between heterotrophy andphototrophy. The cryptophyte (Teleaulax)-Mesodinium-Dinophysis (TMD) complex is a specificpredator-prey interaction of different types of mixoplankton and a good example of the complexityof mixoplankton interaction and trophodynamics. The specialist non-constitutive mixoplankton(SNCM) Mesodinium acquires its chloroplasts strictly from a specific constitutive mixoplankton(CM) cryptophyte, while the harmful algal bloom (HAB) species Dinophysis acquires its third-handchloroplasts exclusively from Mesodinium.The generic NPZ-style protist model developed here shows that mixoplankton displays dynamicsthat are distinctly different from strict heterotrophs and autotrophs in terms of growth and theway they shape their environment. In addition, there is a clear niche separation between differentmixoplankton types (general non-constitutive mixoplankton (GNCM), SNCM and CM) according tonutrient, prey and light resource availabilities indicating a niche separation of each type. Thus,considering the different mixoplankton functional types in specialised multi-organism relationshipsas they are found in the TMD-complex may be important for their understanding and accurateprediction of growth and biomass development. Currently, none of the many models of Dinophysiscapture the biological dependencies. Results from a nitrogen-based TMD model suggest thatthe timing and quantity of prey availability is crucial for the bloom dynamics of Mesodinium andDinophysis. Some CMs may only feed when phosphate is the limiting nutrient. The results ofthe variable stoichiometric “Perfect Beast” model that was configured as Teleaulax amphioxeia incombination with experimental data strongly suggest that the cryptophyte feeds on bacteria tocompensate for phosphate limitation.This work shows the importance of considering mixoplankton in ecosystem models alongsidestrict heterotrophs and autotrophs and that distinction between different mixoplankton functionaltypes matters. Mixoplankton distinctly differ in their nutrient utilisation and growth dynamics.Predator-prey interactions have different implications for mixoplankton than for heterotrophs andtheir inclusion in models could improve our understanding of the formation of harmful mixoplanktonblooms. The unique physiology of mixoplankton and their nutrient utilisation and trophic levelsneed consideration in species specific models.Le mixoplancton inclut les protistes planctoniques capables de phototrophie et de phagotrophie.Ces organismes sont de plus en plus reconnus comme une partie importante du plancton marin.Toutefois, la plupart des modèles mathématiques planctoniques existants supposent encoreune stricte dichotomie entre les organismes phototrophes et hétérotrophes et peu de modèlesconsidèrent l’activité mixoplanctonique comme une synergie entre les deux modes trophiques.De nombreux types fonctionnels mixoplanctoniques différents existent dans un gradient entrel’hétérotrophie et la phototrophie. Le complexe cryptophyte (Teleaulax)-Mesodinium-Dinophysis(TMD) est une interaction prédateur-proie spécifique entre différents types de mixoplancton et unbon exemple de la complexité des interactions et des relations trophodynamiques du mixoplancton.Mesodinium, mixoplancton spécialiste non constitutif (SNCM), ne peut acquérir ses chloroplastesque de cryptophytes (mixoplancton constitutif (CM)) spécifiques (tel que Teleaulax), tandis quel’espèce Dinophysis, responsable d’efflorescences algales nuisibles, acquiert ses chloroplastesexclusivement de Mesodinium. Le modèle générique de protistes, de type NPZ, développé dansce travail montre que le mixoplancton présente une dynamique nettement différente de celle deshétérotrophes et autotrophes strictes en termes de croissance et de la façon dont ils façonnentleur environnement. En outre, il existe une séparation de niches claire entre les différents typesde mixoplancton (mixoplancton généraliste non-constitutif (GNCM), SNCM et CM) en fonction dela disponibilité en lumière, en nutriments et en proies. En conséquence, la prise en compte desdifférents types fonctionnels du mixoplancton dans des relations multi-organismes spécialisées,telles qu’on les trouve dans le complexe TMD, peut être importante pour leur compréhension et laprédiction précise de leur croissance et biomasse. Actuellement, aucun des modèles existants deDinophysis ne rend compte de ces dépendances biologiques. Les résultats d’un modèle TMD basésur l’azote suggèrent que le moment et la quantité de proies disponibles sont des facteurs cruciauxpour la dynamique de Mesodinium et de Dinophysis. Certains CM peuvent se nourrir uniquementlorsque le phosphate est le nutriment limitant. Les résultats du modèle à stoechiométrie variable"Perfect Beast", qui a été configuré pour représenter Teleaulax amphioxeia sur base de donnéesexpérimentales, suggèrent fortement que le cryptophyte se nourrit de bactéries pour compenserla limitation en phosphate. Ce travail montre l’importance de prendre en compte le mixoplanctondans les modèles d’écosystème en plus des hétérotrophes et des autotrophes stricts et que ladistinction entre les différents types fonctionnels de mixoplancton est importante. Le mixoplanctonse distingue par son utilisation des nutriments et sa dynamique de croissance. Les interactionsprédateur-proie n’ont pas les mêmes implications pour le mixoplancton que pour les hétérotropheset leur prise en compte dans les modèles pourrait améliorer notre compréhension de la formationdes efflorescences nuisibles de mixoplancton. La physiologie unique du mixoplancton, sonutilisation des nutriments et ses niveaux trophiques doivent être pris en compte dans les modèlesspécifiques aux espèces.
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
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Ballón, Soto Roberto Michael. "Étude acoustique du macrozooplancton au Pérou : estimation de biomasse, distribution spatiale, impact du forçage physique, et conséquences sur la distribution des poissons fourrage." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20052/document.
Full textAbstract:
La partie nord du Système du courant de Humboldt (NSCH) couvre moins de 0.1% de la surface océanique mondiale mais produit plus de poisons, en particulier d'anchois du Pérou (Engraulis ringens), par unité de surface que n'importe quelle autre région du monde. Bien que ce système produise suffisamment de macrozooplancton pour alimenter les populations de poisson fourrage, le manque d'informations sur ce compartiment limite nos capacités d'étude. L'objectif de cette thèse est d'étudier la dynamique de la distribution spatiotemporelle de la biomasse en macrozooplancton du NSCH en relation avec l'environnement physique et les poissons fourrage, à différentes échelles. Pour ce faire une méthode acoustique bi-fréquences a été développée et appliqué à des séries de données acoustiques historiques. Des informations à haute résolution ont ainsi pu être extraite sur la biomasse et les patrons de distribution du macrozooplancton, de la galathée pélagique 'munida', des poissons et des autres compartiments. Cette méthode nous a également permis d'estimer l'extension verticale de la communauté épipélagique (ZVEEC). Nous avons démontré que ZVEEC coïncide avec la limite supérieure de la zone de minimum d'oxygène (ZMO), ce qui permet de produire des donnés spatialisées à haute résolution de la limite supérieure de la ZMO et d'estimer le volume d'habitat de l'anchois. Notre estimation de biomasse en macrozooplancton, environ quatre fois supérieures aux estimations antérieures, est en accord avec les découvertes récentes sur l'écologie trophique des poissons fourrage du NSCH et fournit des éléments étayant les théories actuelles sur l'origine de la haute productivité en poissons du NSCH. L'étude des impacts des structures physiques de submeso- et mesoéchelle sur la distribution du macrozooplancton supporte l'hypothèse d'une structuration de type 'bottom-up'. Nous avons également mis en évidence l'impact de la structuration spatiale du macrozooplancton sur la distribution des poissons fourrage. Les données physiques et biologiques à haute résolution obtenues grâce à cette étude ouvrent de nouvelles perspectives pour réaliser des études écologiques intégrées à échelles multiples et pour calibrer les modèles biogéochimiques, trophiques ou End-to-EndThe Northern Humboldt Current system (NHCS) represents less than 0.1% of the world ocean surface but produces more fish, mainly Peruvian anchovy (Engraulis ringens), per unit area than any other region in the world. Although this system produces enough macrozooplankton to feed its high production of forage fish, the paucity of information on zooplankton hampers research in the system. The objective of this study was to investigate the multiscale dynamics of the spatiotemporal distribution of the macrozooplankton biomass off Peru in relation to the physical environment and their fish predators. For that a bi-frequency acoustic method was developed and applied to extract, from historical acoustic data, high-resolution information on the biomass and the patterns of distribution of macrozooplankton, the pelagic red squad 'munida', fish and other marine compartments. This method also allows estimating the vertical extension of this epipelagic community (ZVEEC). We demonstrated that ZVEEC coincide with the upper limit of the oxygen minimum zone (OMZ), which allowed both producing high-resolution spatial data of the upper limit of the OMZ and estimating the volume habitat of anchovy. The estimated macrozooplankton biomass was about four times higher than previously reported. This estimate is in agreement with the recent findings on forage fish trophic ecology and supports the current hypotheses explaining the NHCS high fish production. The study of the impacts of the submeso- and mesoscale physical structures on macrozooplankton provided evidence of the bottom-up physical effect on the distribution of macrozooplankton biomass. We also found further evidence of the structuring bottom-up effect that macrozooplankton exert on forage fish. The high-resolution biological and physical data obtained in this study opens new perspective to perform integrated multiscale ecological studies and to calibrate biogeochemical, trophic and End-to-End models
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Meakin, Nicholas G. "Metagenomic analyses of marine new production under elevated CO2 conditions." Thesis, University of Stirling, 2009. http://hdl.handle.net/1893/1555.
Full textAbstract:
A mesocosm experiment was carried out in a Norwegian fjord near Bergen in May 2006, with the main objective being the study of the effects of increasing concentrations of atmospheric CO2 (and associated effects such as increased acidification) on blooms of natural marine coastal plankton. Three mesocosms were bubbled with CO2(g) to achieve a high (~700ppm) CO2 concentration (pH ~7.8) to simulate predicted future conditions as a result of rising atmospheric CO2 concentrations. Another three mesocosms were treated as controls and bubbled with ambient air to represent a near pre-industrial scenario (atmospheric CO2 concentration ~300ppm, surface seawater pH ~8.15). Blooms in the mesocosms were stimulated by the addition of nutrients at a near-Redfield ratio ([N:P] ≈ [16:1]), and scientific measurements and analyses were carried out over the course of the blooms for approximately one month. Of particular interest in this study were the autotrophic plankton. The diversity and activities of these microorganisms under the two treatments was therefore investigated. By designing and using new degenerate primers specifically targeting ‘Green-type’ (Form IA and IB), ‘Red-type’ (Form IC and ID) and Form II RuBisCO, analysis of primary producers was carried out using PCR and either gDNA or cDNA (mRNA) templates from key time points spanning the complete duration of the blooms throughout the mesocosm experiment. Over 1250 novel RuBisCO large subunit sequences have been fully annotated and deposited in the NCBI GenBank® database. These sequences revealed distinct changes in the diversity of primary producers both over the courses of the blooms and between treatments. Particularly striking was the effect of acidification on the community structure of the eukaryotic picoplankton, Prasinophytes. A clade of prasinophytes closely related to Micromonas pusilla showed a distinct preference for the high CO2 conditions; a laboratory-based experiment confirmed the high tolerance of Micromonas pusilla to lower pH. Conversely, a clade related to Bathycoccus prasinos was almost entirely excluded from the high CO2 treatments. Clades of form II RuBisCO-containing dinoflagellates were also abundant throughout the experiment in both treatments. The high similarity of some of these clades to the toxin-producing species Heterocapsa triquetra and Gonyaulax polyedra, and apparent high tolerance of some clades to high CO2 conditions, is perhaps cause for concern in a high CO2 world and demands further research. In parallel with the RubisCO work, new primers were designed that target the gene encoding the Fe protein of nitrogenase (NifH). 82 Bergen genomic nifH sequences have been annotated and submitted to GenBank®. These sequences include those from organisms related to Alpha, Beta, and Gammaproteobacteria, and Cluster II and Cluster III sequences that align most closely with anaerobic Bacteria, Gram positive, and/or sulphur-reducing Bacteria. The biggest surprise, however, was the apparent abundance and significance of a Rhodobacter sphaeroides-like microorganism throughout the duration of the experiment in both treatments. Whilst this clade was unsurprisingly absent in the RuBisCO cDNA libraries, all but two of 128 nifH cDNA clones analysed were identical to the gene from Rhodobacter sphaeroides. This shows that this clade was potentially fixing N2 throughout the entire experiment, even in the presence of combined N added to both sets of mesocosms at the start of the experiment. A group of Rhodobacter sphaeroides-like microorganisms present at Bergen may therefore have been an unexpected source of new N during the experiment and contributed to the maintenance of the mesocosm communities as nutrients became depleted. One organism dominated the autotrophic communities after the blooms in both treatments. Synechococcus spp. Form IA rbcL clones most closely related to the coastal strain Synechococcus sp. strain CC9902 were recovered throughout the experiment but were particularly numerous toward the end of the experiment and dominated the “Green-type” libraries at this time. Initially, rbcL clones from these cyanobacteria were mostly derived from the ambient CO2 mesocosms but were equally distributed between treatments by the end of the experiment. This suggests that cyanobacteria related to strain CC9902 may be less tolerant of elevated CO2 (which was greatest at the beginning rather than the end of the experiment). However, despite the mesocosms being Pi-limited at the end of the experiment, several Synechococcus species (including those related to strain CC9902 and another coastal strain, CC9311) thrived. Following on from this observation, Pi uptake and assimilation mechanisms in a Synechococcus species were investigated in the laboratory. This led to the sequencing and characterisation of a pstS gene from the marine cyanobacterium Synechococcus sp. WH 8103. Unlike conventional pstS, it was discovered that the pstS II gene in this organism is constitutively expressed and unresponsive to or only weakly regulated by Pi supply. The use of PstS/pstS as a marker for P-limitation in natural samples, therefore, should be interpreted with caution.