Rozprawy doktorskie: „Plankton”

1

Striebel, Maren. "PLANKTON DYNAMICS". Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-92597.

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Del, Giorgio Paul A. "Heterotrophy in lake plankton". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41362.

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The overall aim of this thesis was to determine the relative importance of heterotrophy and autotrophy in lake plankton. Empirical analyses using extensive surveys of literature data revealed three specific patterns in metabolism and biomass structure in freshwater plankton. First, the ratio of phytoplankton production to plankton respiration (P/R ratio) tends to be low in unproductive lakes ($<$1), and increases along gradients of enrichment. Second, the contribution of planktonic heterotrophs (bacteria and zooplankton) to community respiration is highest in oligotrophic lakes. Third, planktonic heterotrophs dominate community biomass in oligotrophic lakes, whereas phytoplankton increasingly dominate plankton biomass along gradients of enrichment. These three distinct patterns were then tested simultaneously in a set of lakes that span a wide trophic gradient. Results indicated that the plankton of oligotrophic and mesotrophic lakes were characterized by P/R ratios well below unity, and a high contribution of heterotrophs to both community respiration and biomass. These trends are completely the opposite in the most productive lakes. The plankton communities of oligotrophic temperate lakes are predominantly heterotrophic and extensively utilize external inputs of carbon, and therefore only the plankton of eutrophic lakes conformed to the classical phytoplankton-based food web. In most lakes, excess heterotrophic activity could be supported by inputs of organic matter from the drainage basin. Excess plankton respiration, fueled by allochthonous organic carbon, could represent an important source of CO$ sb2$ to lakes.

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Birch, Daniel A. "Plankton modeling at multiple scales". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3274810.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed October 9, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 132-138).

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Kotrc, Benjamin. "Evolution of Silica Biomineralizing Plankton". Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10969.

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The post-Paleozoic history of the silica cycle involves just two groups of marine plankton, radiolarians and diatoms. I apply paleobiological methods to better understand the Cenozoic evolution of both groups. The Cenozoic rise in diatom diversity has long been related to a concurrent decline in radiolarian test silicification. I address evolutionary questions on both sides of this coevolutionary coin: Was the taxonomic diversification of diatoms accompanied by morphological diversification? Is our view of morphological diatom diversification affected by sampling biases? What evolutionary mechanisms underlie the macroevolutionary decline in radiolarian silicification? Conventionally, diatom diversification describes a steep, monotonic rise, a view recently questioned due to sampling bias. For a different perspective, I constructed a diatom morphospace based on discrete characters, populated through time using an occurrence-level database. Distances between taxa in morphospace and on a molecular phylogeny are not strongly correlated, suggesting that morphospace was explored early in their evolutionary history, followed by relative stasis. I quantified morphospace occupancy through time using several disparity metrics. Metrics describing average separation of taxa show stasis, while metrics describing occupied volume show an increase with time. Disparity metrics are also subject to sampling biases. Under subsampling, I find that disparity metrics show varied responses: metrics describing separation of taxa into morphospace are unaffected, while those describing occupied volume lose their clear increases. Disparity can have geographic components, analogous to $\alpha$ and $\beta$ taxonomic diversity; I find more evidence of stasis in an analysis of $\bar{\alpha}$ disparity. Overall, these results suggest stasis in Cenozoic diatom disparity. The radiolarian decline in silicification could result from either macroevolutionary processes operating above the species level (punctuated queilibria) or anagenetic changes within lineages. I measured silicification in three phyletic lineages, Stichocorys, Didymocyrtis, and Centrobotrys, from four tropical Pacific DSDP sites. Likelihood-based model fitting finds no strong support for directional evolution, pointing toward selection among species, rather than within species. Each lineage shows a different trajectory, perhaps due to differences in the ecological role played by the test. Because Stichocorys shows close correspondence to the assemblage-level trend, abundance may be an important factor through which within-lineage changes can influence the macroevolutionary pattern.
Earth and Planetary Sciences

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Mantilla, Jose G. (Jose Gabriel) 1972. "Models of plankton biomass spectra". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80212.

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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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Kramer, Kurt A. "Identifying plankton from grayscale silhouette images". [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001402.

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Pitchford, Jonathan William. "Dynamics of multi-species plankton populations". Thesis, University of Leeds, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397772.

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Pascual-Dunlap, Maria Mercedes. "Some nonlinear problems in plankton ecology". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38049.

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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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11

Prince, Emily Katherine. "Chemically-mediated interactions in the plankton:". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22701.

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Thesis (Ph. D.)--Biology, Georgia Institute of Technology, 2008.
Committee Chair: Kubanek, Julia; Committee Member: Hay, Mark; Committee Member: Jiang, Lin; Committee Member: Pavia, Henrik; Committee Member: Snell, Terry.

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12

Gjersdal, Jan. "Instrumentering og styring av produksjonsprosess for plankton". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14084.

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I denne oppgaven er det presentert instrumentering og reguleringssystem av produksjonsprosess for plankton. Systemet er utviklet og implementering med to tanker for produksjon av planktonet rotatorier. PC brukes som styresystem og grensesnitt mot bruker. Regulering av rotatorietetthet med en ny strategi for tilførsel av fôr og vann er implementert og testet. Systemet fungerte tilfredsstillende foruten den nye strategien som trenger mer testing for å fungere optimalt.

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13

Basu, Ben Kumar. "Plankton development and trophic interactions in rivers". Thesis, University of Ottawa (Canada), 1997. http://hdl.handle.net/10393/10146.

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The factors regulating the development and trophic interactions of planktonic communities were determined in 31 medium to large size temperate rivers. In addition, the Rideau River, Ontario, was studied in detail over three field seasons. Variables measured included: phytoplankton biomass as measured by chlorophyll $\alpha$ concentration; zooplankton biomass (rotifers and crustaceans); heterotrophic bacterial abundance; heterotrophic flagellate abundance; nutrient concentrations (phosphorus and nitrogen); dissolved organic carbon concentration; river discharge; water residence time; depth; temperature; and light attenuation. Phytoplankton was abundant in eutrophic rivers ($>$15 $\mu$g L$\sp{-1}$ of chlorophyll a) and was most strongly related to nutrient concentrations, primarily total phosphorus, which explained up to 76% of the variation in chlorophyll a. Phytoplankton biomass in the rivers was not related to the hydrological parameters of water residence time or discharge, possibly due to the short generation time of phytoplankton (hours to days). Light did not appear to limit phytoplankton biomass due to shallow depths and extensive vertical mixing. In the Rideau River phytoplankton biomass exhibited longitudinal heterogeneity, but in general increased in a downstream direction, concomitant with increases in nutrient concentrations. Phytoplankton biomass did not appear to be affected by zooplankton grazing in the rivers. However, phytoplankton biomass may have been negatively impacted by benthic filter feeders, in particular the invasive zebra mussel (Dreissena polymorpha), in the downstream reaches of the Rideau River. Zooplankton biomass in the rivers was low (usually 20 $\mu$g L$\sp{-1}$ dry mass) and small taxa dominated the zooplankton communities (e.g. rotifers, bosminids). Large zooplankton taxa, such as Daphnia sp., were much less abundant. Due to longer generation times (days to weeks), zooplankton biomass was primarily related to water residence time which explained 33% of the variation. Zooplankton appeared susceptible to advective loss in the rivers. A positive resource effect of either nutrients or phytoplankton on zooplankton biomass, typically observed in lakes, was weaker in the rivers. In comparison to lakes, zooplankton appeared less tightly coupled to phytoplankton. As with phytoplankton, zooplankton biomass in the Rideau River increased with downstream travel and appeared to be negatively affected by benthic filter feeders. Heterotrophic bacteria were abundant in the rivers (4.5 $\times$ 10$\sp6$ cells ml$\sp{-1})$ and, as in lakes, bacteria were most strongly related to nutrient concentrations (total phosphorus) and phytoplankton biomass (chlorophyll a). In contrast to lakes, no relationship between bacterial abundance and dissolved organic carbon was observed, possibly due to the more allochthonous, refractory nature of river dissolved organic carbon. Heterotrophic flagellates were also abundant in the rivers $(4.0\times10\sp{3}$ cells ml$\sp{-1})$ and were most strongly related to bacterial abundance and nutrient concentrations (total phosphorus). Neither bacterial nor flagellate abundance was related to water residence time. A negative relationship between zooplankton biomass and bacterial or flagellate abundance was not observed, possibly because of the low biomass (hence low grazing pressure) of zooplankton in the rivers. Due to the scarcity of zooplankton in rivers, there may be little transfer of energy from the planktonic microbial food web to planktonic metazoans.

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Currie, Warren J. S. "Scale-invariance and patchiness in the plankton". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ61972.pdf.

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15

Guirey, Emma Jane. "Application of synchronisation theory to plankton patchiness". Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/63137/.

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This study applies a metapopulation dynamics approach to modelling a distribution of plankton by representing a region of ocean as an ensemble of plankton populations interacting through the stirring and mixing eects of the ow. The methods of synchronisation theory are applied within this framework to gain insight into emergent spatial structure in biophysical simulations. The manifestation of synchronisation, including statistically stable local clustering of populations, frequency-locking or phase-locking of the entire ensemble and fully synchronised dynamics, is found to depend upon: the biological model used; the strength of mixing between populations; the number of populations or, equivalently, spatial resolution of the modelled region; the level of mismatch between and spatial arrangement of population natural frequencies; the strength of stirring of the ensemble at spatial scales larger than the grid-cell. The study therefore highlights a number of biophysical modelling parameters determining the properties of emergent spatial structure in simulations of surface ocean biological dynamics. This study shows that persistent spatial heterogeneity (patchiness) can result from what intuitively should be a homogenising in uence: mixing can increase the level of disorder between the plankton populations. Furthermore, the work shows that synchronisation eects occur generically under a range of simulation scenarios, giving condence that synchronisation theory can explain some of the spatial structure, or `patchiness', observed in plankton distributions, and providing one possible answer as to how populations of planktonic organisms maintain coherent spatial structures under the mixing and stirring action of the oceanic flow.

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Engström-Öst, Jonna. "Effects of cyanobacteria on plankton and planktivores". Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/engstrom-ost/.

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Menezes, Sunshine. "Nanoplankton biodiversity in the Pettaquamscutt River estuary, Rhode Island, U.S.A. /". View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3186914.

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Beck, Kristin. "Experimentelle Überprüfung der "Intermediate Disturbance Hypothesis" (Connell 1978) an Modell-Lebensgemeinschaften planktischer Bakterienisolate". [S.l. : s.n.], 2000. http://e-diss.uni-kiel.de/diss.

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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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Svee, Astrid. "Development and Testing of an Acoustic Plankton Recorder". Doctoral thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1477.

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Recent years have brought cross-disciplinary focus on possibilities, constraints and consequences of large scale zooplankton harvesting. Development of acoustic measurement technology is an important part of that work. Because of the small size of the plankton, the measurement frequencies have to be high compared to fishery acoustics. Based on a model of the size and shape of the plankton and its physical properties, the use of multiple frequency measurements will allow inverse modeling of the size and concentration of plankton. This thesis presents the development and test results of an Acoustical Plankton Recorder (APR). The system uses three frequencies, 200 kHz, 710 kHz, and 1 MHz. The system parameters are designed with a focus on measuring the zooplankton Calanus finmarchicus, which plays an important role in the Norwegian Sea ecosystem. The APR is a prototype instrument built to gain experience for future generations of instruments for plankton measurements. Different aspects of multi-frequency acoustical measurements are discussed with a focus on uncertainties and critical factors. The results from various experiments and measurements are presented. The estimated concentration of scatterers from data recovered by the Acoustical Plankton Recorder shows good agreement with biological samples.

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21

Haupt, Florian. "Plankton vertical migrations - Implications for the pelagic ecosystem". Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-135130.

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Sanderson, Rory J. "Ecology of freshwater plankton in contrasting hydraulic environments". Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29785.

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The effects of contrasting water residence time on the planktonic community of three water bodies was studied. The sites were Rutland Water, Covenham reservoir and the River Nene, in order of decreasing retention time. The river was the only site where the residence time was sufficiently short to directly impact upon planktonic populations. The importance of physical mechanisms of control in the river was indicated by the dominance of r-selected phytoplankton, namely diatoms and green algae, and zooplankton, namely rotifers. This pattern was in contrast to that of the reservoirs in which slower-growing cyanobacteria and cladocerans dominated. Riverine rotifers were found to have rapid population turnover, due to a combination of short pre-adult duration and high maximum growth rates. Some species also showed a shift in reproductive behaviour to the constant production of resting eggs. This was assumed to convey benefits in a system where resting stages may be less susceptible than adults to downstream displacements. The total chlorophyll 'a' concentration achieved per unit phosphorus was significantly lower in the river than either of the reservoirs. Algal density was negatively associated with discharge in the Nene, suggesting the importance of physical control. The relationship was not a simple one, however, as periods of increased retention time during the summer were associated with low algal density. The absolute density of rotifers was found to be constrained by discharge. Animals were rare above a threshold flow velocity of 0.08ms-1. Simple models of water flow in open channels were insufficient to account for the continued persistence of a plankton in the Nene given the level of advection. It was assumed that the overall retention time of the system was increased by the presence of dead zones within the channel which 'held' planktonic organisms for sufficient time for populations to develop. This behaviour was important during the spring when population density increased in the main channel.

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Orgill, Christopher H. "Plankton population density measurement by acousto-electronic testing". Thesis, Bangor University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278548.

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Pan, Anon Maria. "Decapod crustacean larvae in Scottish (UK) coastal plankton". Thesis, University of Aberdeen, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499700.

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Decapod larval assemblages were studied at two sites in Scottish coastal waters, Stonehaven and Loch Ewe. Plankton data from 4.5 years at Stonehaven and from 2 years at Loch Ewe were analysed, allowing the study of decapod larval cycles, species composition and seasonality at these locations. An 8 years time series of weekly data on total abundance of decapod larvae from Stonehaven and 4 years and 8 months time series from Loch Ewe were also studied. The influence of environmental variables in the patterns observed was analysed using mixed modelling techniques. The results showed differences in abundance, although not in diversity, between the two sampling locations. The temperature was the main factor affecting the patterns observed, followed by food availability (expressed as chlorophyll a) and salinity. Artificial substrates were employed to study the settlement and the early establishment phases for the decapod community at Stonehaven area. Species composition and occurrence of megalopae and juveniles and links with the mesoplanktonic larvae were studied. A significant correlation was detected between the abundance of megalopae and early juveniles in the collectors and the abundance of decapod larvae in the plankton a month earlier. The same was observed for the species Pisidia longicornis, but not for other taxa. Real-Time PCR was successfully employed in the identification of Liocarcinus depurator, Cancer pagurus, Carcinus maenas and Necora puber larvae. This technique allowed inference of the annual cycle of L. depurator and showed the potential of this method to obtain relative quantifications of the larvae. A photographic guide for the decapod species identified was created, providing a good overview of the species present in these two Scottish coastal locations, useful as a complementary tool to the dichotomous keys.

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Yool, Andrew. "The dynamics of open-ocean plankton ecosystem models". Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/1129/.

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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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Gonzalez, de Macias Ma Refugio. "Plankton and physiochemical factors in a vernal pool". Scholarly Commons, 1989. https://scholarlycommons.pacific.edu/uop_etds/2183.

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Recently the uniqueness of the vernal pool habitat has been recognized by several groups of biologists. A survey of the literature reveals that interest of botanists, but one notes a lack of information of plankton which are so fundamental in the food web. Therefore, a taxonomic survey of the plankton seems appropriate. In the present study, the abundance of the predominant species of plankton were studied during a seasonal and also diurnal cycle. A possible correlation of this information with some physicochemical factors was also tested. Because of time constraints this study was limited to one pool but hopefully other researchers will extend this work in the future.

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Höglander, Helena. "Studies of Baltic Sea plankton : spatial and temporal patterns /". Stockholm : Department of Systems Ecology, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-323.

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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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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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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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Baird, Mark E. "Towards a verified mechanistic model of plankton population dynamics". Thesis, University of Warwick, 1999. http://wrap.warwick.ac.uk/1123/.

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Plankton are a signicant component of the biogeochemical cycles that impact on the global climate. Plankton ecosystems constitute around 40 % of the annual global primary productivity, and the sinking of plankton to the deep ocean (the so-called biological pump) is the largest permanent loss of carbon from the coupled atmosphere-surface ocean-land system. The biological pump need only increase by 25 % to cancel the anthropogenically-released ux of CO2 into the atmosphere. Mechanistic models of atmosphere-ocean dynamics have proved to have superior predictive capabilities on climate phenomena, such as the El Ni~no, than empirical models. Mechanistic models are based on fundamental laws describing the underlying processes controlling a particular system. Existing plankton population models are primarily empirical, raising doubts to their ability to forecast the behaviour of the plankton system, especially in an altered global climate. This thesis works towards a mechanistic model of plankton population dynamics based primarily on physical laws, and using laboratory-determined parameters. The processes modelled include: diusion and convection to the cell surface, light capture by photosynthetic pigments, sinking and encounter rates of predators and prey. The growth of phytoplankton cells is modelled by analogy to chemical kinetics. The equations describing each process are veried by comparison to existing laboratory experiments. Process-based model verication is proposed as a superior diagnostic tool for model validation than verication based on the changing state of the system over time. To increase our ability to undertake process-based verication, a model of stable isotope fractionation during phytoplankton growth is developed and tested. The developed model has been written to complement other process-based models of biogeochemical cycles. A suite of process-based, biogeochemical models, coupled to an atmosphere-ocean circulation model, will have superior predictive capabilities compared with present global climate models.

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33

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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Hu, Qiao Ph D. Massachusetts Institute of Technology. "Application of statistical learning theory to plankton image analysis". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39206.

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Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2006.
Includes bibliographical references (leaves 155-173).
A fundamental problem in limnology and oceanography is the inability to quickly identify and map distributions of plankton. This thesis addresses the problem by applying statistical machine learning to video images collected by an optical sampler, the Video Plankton Recorder (VPR). The research is focused on development of a real-time automatic plankton recognition system to estimate plankton abundance. The system includes four major components: pattern representation/feature measurement, feature extraction/selection, classification, and abundance estimation. After an extensive study on a traditional learning vector quantization (LVQ) neural network (NN) classifier built on shape-based features and different pattern representation methods, I developed a classification system combined multi-scale cooccurrence matrices feature with support vector machine classifier. This new method outperforms the traditional shape-based-NN classifier method by 12% in classification accuracy. Subsequent plankton abundance estimates are improved in the regions of low relative abundance by more than 50%. Both the NN and SVM classifiers have no rejection metrics. In this thesis, two rejection metrics were developed.
(cont.) One was based on the Euclidean distance in the feature space for NN classifier. The other used dual classifier (NN and SVM) voting as output. Using the dual-classification method alone yields almost as good abundance estimation as human labeling on a test-bed of real world data. However, the distance rejection metric for NN classifier might be more useful when the training samples are not "good" ie, representative of the field data. In summary, this thesis advances the current state-of-the-art plankton recognition system by demonstrating multi-scale texture-based features are more suitable for classifying field-collected images. The system was verified on a very large real-world dataset in systematic way for the first time. The accomplishments include developing a multi-scale occurrence matrices and support vector machine system, a dual-classification system, automatic correction in abundance estimation, and ability to get accurate abundance estimation from real-time automatic classification. The methods developed are generic and are likely to work on range of other image classification applications.
by Qiao Hu.
Ph.D.

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35

Wallhead, Philip John. "Accounting for unpredictable spatial variability in plankton ecosystem models". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63762/.

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Limitations on our ability to predict fine-scale spatial variability in plankton ecosystems can seriously compromise our ability to predict coarse-scale behaviour. Spatial variability which is deterministically unpredictable may distort parameter estimates when the ecosystem model is fitted to (or assimilates) ocean data, may compromise model validation, and may produce mean-field ecosystem behaviour discrepant with that predicted by the model. New statistical methods are investigated to mitigate these effects and thus improve understanding and prediction of coarse-scale behaviour e.g. in response to climate change. First, the standard model fitting technique is generalised to allow model-data ‘phase errors’ in the form of time lags, as has been observed to approximate mesoscale plankton variability in the open ocean. The resulting ‘variable lag fit’ is shown to enable ‘Lagrangian’ parameter recovery with artificial ecosystem data. A second approach employs spatiotemporal averaging, fitting a ‘weak prior’ box model to suitably-averaged data from Georges Bank (as an example), allowing liberal biological parameter adjustments to account for mean effects of unresolved variability. A novel skill assessment technique is used to show that the extrapolative skill of the box model fails to improve on a strictly empirical model. Third, plankton models where horizontal variability is resolved ‘implicitly’ are investigated as an alternative to coarse or higher explicit resolution. A simple simulation study suggests that the mean effects of fine-scale variability on coarse-scale plankton dynamics can be serious, and that ‘spatial moment closure’ and similar statistical modelling techniques may be profitably applied to account for them.

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36

Edwards, Andrew Michael. "A rational dynamical-systems approach to plankton population modelling". Thesis, University of Leeds, 1997. http://etheses.whiterose.ac.uk/21072/.

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Understanding the dynamics of plankton populations is of major importance since plankton form the basis of marine food webs throughout the world's oceans and play a significant role in the global carbon cycle. In this thesis we examine the dynamical behaviour of plankton models, exploring sensitivities to the number of variables explicitly modelled, to the functional forms used to describe interactions, and to the parameter values chosen. The practical difficulties involved in data collection lead to uncertainties in each of these aspects of model formulation. The first model we investigate consists of three coupled ordinary differential equations, which measure changes in the concentrations of nutrient, phytoplankton and zooplankton. Nutrient fuels the growth of the phytoplankton, which are in turn grazed by the zooplankton. The recycling of excretion adds feedback loops to the system. In contrast to a previous hypothesis, the three variables can undergo oscillations when a quadratic function for zooplankton mortality is used. The oscillations arise from Hopf bifurcations, which we track numerically as parameters are varied. The resulting bifurcation diagrams show that the oscillations persist over a wide region of parameter space, and illustrate to which parameters such behaviour is most sensitive. The oscillations have a period of about one month, in agreement with some observational data and with output of larger seven-component models. The model also exhibits fold bifurcations, three-way transcritical bifurcations and Bogdanov-Takens bifurcations, resulting in homo clinic connections and hysteresis. Under different ecological assumptions, zooplankton mortality is expressed by a linear function, rather than the quadratic one. Using the linear function does not greatly affect the nature of the Hopf bifurcations and oscillations, although it does eliminate the homoclinicity and hysteresis. We re-examine the influential paper by Steele and Henderson (1992), in which they considered the linear and quadratic mortality functions. We correct an anomalous normalisation, and then use our bifurcation diagrams to interpret their findings. A fourth variable, explicitly modelling detritus (non-living organic matter), is then added to our original system, giving four coupled ordinary differential equations. The dynamics of the new model are remarkably similar to those of the original model, as demonstrated by the persistence of the oscillations and the similarity of the bifurcation diagrams. A second four-component model is constructed, for which zooplankton can graze on detritus in addition to phytoplankton. The oscillatory behaviour is retained, but with a longer period. Finally, seasonal forcing is introduced to all of the models, demonstrating how our dynamical systems approach aids understanding of model behaviour and can assist with model formulation.

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Piltz, Sofia Helena. "Models for adaptive feeding and population dynamics in plankton". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:811fd94d-d58e-48fa-8848-ad7dc37a099f.

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Traditionally, differential-equation models for population dynamics have considered organisms as "fixed" entities in terms of their behaviour and characteristics. However, there have been many observations of adaptivity in organisms, both at the level of behaviour and as an evolutionary change of traits, in response to the environmental conditions. Taking such adaptiveness into account alters the qualitative dynamics of traditional models and is an important factor to be included, for example, when developing reliable model predictions under changing environmental conditions. In this thesis, we consider piecewise-smooth and smooth dynamical systems to represent adaptive change in a 1 predator-2 prey system. First, we derive a novel piecewise-smooth dynamical system for a predator switching between its preferred and alternative prey type in response to prey abundance. We consider a linear ecological trade-off and discover a novel bifurcation as we change the slope of the trade-off. Second, we reformulate the piecewise-smooth system as two novel 1 predator-2 prey smooth dynamical systems. As opposed to the piecewise-smooth system that includes a discontinuity in the vector fields and assumes that a predator switches its feeding strategy instantaneously, we relax this assumption in these systems and consider continuous change in a predator trait. We use plankton as our reference organism because they serve as an important model system. We compare the model simulations with data from Lake Constance on the German-Swiss-Austrian border and suggest possible mechanistic explanations for cycles in plankton concentrations in spring.

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38

Remsen, Andrew Walker. "Evolution and field application of a plankton imaging system". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002429.

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39

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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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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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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42

Burren, Claire Louise. "A numerical modelling investigation of the impact of mesoscale heterogeneity on oceanic primary productivity". Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239965.

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Luo, Tong. "Scaling up support vector machines with application to plankton recognition". [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001154.

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44

Fugagnoli, Alice. "The ratio of plastic to plankton in the Mediterranean Sea". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16962/.

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Plastic pollution is a huge problem that is affecting all the oceans of the Earth. Plastic items end into the sea, break into tiny pieces and pollute the marine environment. The aim of this research is to increase our knowledge on this problem by comparing microplastic and zooplankton distributions. Samples from the Mediterranean Sea and Gibraltar Strait have been collected and analyzed. Plastic fragments have been extracted, weighted, photographed, measured and analyzed with a hyperspectral camera. The planktonic part of the samples has been analyzed identifying the main typology of organisms, taking pictures of the samples and analyzing them with ImageJ to take the measures. Data analysis was focused to the plastic to zooplankton ratio. The results have highlighted that most of the plastic to plankton ratios occurred in the in 1mm-10mm size range, and half of the stations in the Mediterranean sea presented values higher than 1, meaning than there is more plastic than plankton in that size range, for 50% of the Mediterranean. The ratio was higher during the day, due to the ascent of zooplankton during night. The results clearly show that the rank of greater danger is between 1mm to 10mm, and for this reason future samplings should focus on a net for this specific size range, to make sampling more simple and effective. A pollution indicator was created, based on the data collected all around the Mediterranean Sea, which could help find out future danger classifications, and choose the best adoptable strategies to solve the problem. Furthermore, the fact that the higher ratio has been found during the day can help future plastic sampling to focus on this time lapse. Concluding, the data provided by this research will be useful to better understand the degree of plastic contamination of our oceans and give updates to develop quality guidelines according to the Marine Strategy Framework Directive.

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45

Beisner, Beatrix Elisabeth. "Response of plankton community structure to temporal heterogeneity and productivity". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0011/NQ56503.pdf.

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46

Bird, David F. "The ecological importance of algal phagotrophy to lake plankton communities /". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75763.

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The aim of this thesis is to incorporate the smallest organisms, in particular the heterotrophic bacteria and their predators, more fully into current descriptions of aquatic community structure and dynamics. A strong, positive empirical relationship was found between bacterial abundance and chlorophyll concentration in freshwater and marine systems. Common members of the photosynthetic phytoplankton (all chrysophyceans) were shown to be major, even dominant, grazers of these bacteria. This phagotrophic capability is quantitatively important to the bacterioplankton, to the mixotrophs themselves, and in some cases, to the structure of the limnological community as a whole. Grazing by mixo- and heterotrophic protozoans is concentrated on the largest bacterial cells that also have the greatest growth rates. Relatively lower removal rates of the tiniest cells, with low growth rates, is proposed to explain their numerical dominance in lakes.

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Stromberg, K. H. Patrik. "Plankton size distributions and metabolism of the pelagic global ocean". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520657.

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Graziano, Clemente. "Some observations on the plankton of the north Irish Sea". Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329418.

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Buchberger, Felicitas [Verfasser], i Herwig [Akademischer Betreuer] Stibor. "Plankton dynamics and anthropogenic changes / Felicitas Buchberger ; Betreuer: Herwig Stibor". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1222436493/34.

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Gustavsson, Maria. "Kalkningseffekter på plankton : ett mesokosmexperiment i den kalkrika sjön Tåkern". Thesis, Linköpings universitet, Biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130869.

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One of today's major environmental issues is algal blooms linked to eutrophication of lakes and oceans. That is a result of anthropogenic influence with nutrient loads (including phosphorus) from agriculture and industry, which benefits primary production (phytoplankton). Studies have shown that phosphorus availability in the water column can be limited by liming, therefore could be a way to counteract eutrophication. This was tested in the agriculturally surrounded lake Tåkern in southern Sweden, which in its present state is an internationally important bird lake and therefore in several respects would be affected by eutrophication. The purpose of this study was to investigate whether liming would be a good solution to solve any future eutrophication problems in Lake Tåkern. Liming experiments were performed in mesocosms during April 2015 with a mixture of limestone and slaked lime. Quantity and diversity of plankton and water chemical variables were measured before and after liming. Moreover, samples of phytoplankton from a similar experiment conducted in July 2014 were analyzed. Liming did not show any effect on neither phyto- nor zooplankton when performed in spring of 2015. During summer of 2014, there was an increase in number of phytoplankton (ml-1 ) and chlorophyll in controls while the study showed constant levels in treated mesocosms. For zooplankton there was no significant effects of liming on neither quantity nor diversity. Results of this study suggest that liming is not the most appropriate method to resolve eutrophication in Lake Tåkern.

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