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1
Striebel, Maren. "Phytoplankton-Daphnien-Interaktionen Einfluss der Epilimniontiefe auf Phytoplankton-Daphnien-Interaktionen mit Schwerpunkt Phytoplankton". Saarbrücken VDM Verlag Dr. Müller, 2004. http://d-nb.info/989156214/04.
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Durham, William McKinney. "Phytoplankton in flow". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70868.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-120).
Phytoplankton are small, unicellular organisms, which form the base of the marine food web and are cumulatively responsible for almost half the global production of oxygen. While phytoplankton live in an environment characterized by ubiquitous fluid motion, the impacts of hydrodynamic conditions on phytoplankton ecology remain poorly understood. In this thesis, we propose two novel biophysical mechanisms that rely on the interaction between phytoplankton motility and fluid shear and demonstrate how these mechanisms can drive thin phytoplankton layers and microscale cell aggregations. First, we consider 'thin phytoplankton layers', important hotspots of ecological activity that are found meters beneath the ocean surface and contain cell concentrations up to two orders of magnitude above ambient. While current interpretations of their formation favor abiotic processes, many phytoplankton species found in these layers are motile. We demonstrate that layers can form when the vertical migration of phytoplankton is disrupted by hydrodynamic shear. Using a combination of experiments, individual-based simulations, and continuum modeling, we show that this mechanism - which we call 'gyrotactic trapping' - is capable of triggering thin phytoplankton layers under hydrodynamic conditions typical of the environments that often harbor thin layers. Second, we explore the potential for turbulent shear to produce patchiness in the spatial distribution of motile phytoplankton. Field measurements have revealed that motile phytoplankton form aggregations at the smallest scales of marine turbulence - the Kolmogorov scale (typically millimeters to centimeters) - whereas non-motile cells do not. We propose a new mechanism for the formation of this small-scale patchiness based on the interplay of gyrotactic motility and turbulent shear. Contrary to intuition, turbulence does not stir a plankton suspension to homogeneity, but instead drives patchiness. Using an analytical model of vortical flow we show that motility can give rise to a striking array of patchiness regimes. We then test this mechanism using both laboratory experiments and isotropic turbulent flows generated via Direct Numerical Simulation. We find that motile phytoplankton cells rapidly form aggregations, whereas non-motile cells remain randomly distributed. In summary, this thesis demonstrates that microhydrodynamic conditions play a fundamental role in phytoplankton ecology and, as a consequence, can contribute to shape macroscale characteristics of the Ocean.
by William McKinney Durham.
Ph.D.
3
Heilmann, Jens Peter. "Eutrophication, phytoplankton productivity and the size structure of the phytoplankton community". Thesis, Bangor University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263279.
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Tang, Senming. "Seasonal changes in phytoplankton species composition at Port Shelter, Hong Kong, China (1998-1999)". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22718850.
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Maldonado-Pareja, Maria Teresa. "Iron acquisition by marine phytoplankton". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0022/NQ50215.pdf.
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Contant, Jacinthe. "Phytoplankton Communities in Temperate Rivers". Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20623.
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The structure of phytoplankton communities was examined seasonally across five rivers with a focus on small cells and their relative importance. Picophytoplankton (0.2-2 μm), previously considered insignificant in rivers, reached densities as high as those observed in lakes and oceans (~ 10e4-10e5 cells/mL). Their relative importance was not a function of trophic state with the highest contribution to algal biomass found in the most eutrophic river. Body size distributions were analyzed from both chlorophyll-a size fractions and taxonomic enumerations; no significant effect of river or season was detected, suggesting that phytoplankton size distribution is not a useful metric of change in rivers. Unlike lake ecosystems, the rivers were uniformly dominated by small cells (< 20 μm). Taxonomic analyses of the seasonal succession did not reveal a common periodicity of particular divisions (e.g. diatoms). However, strong dominance was more typical of eutrophic rivers even though taxa richness was similar.
7
Foy, R. H. "Phytoplankton growth in Lough Neagh". Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333608.
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Browning, Thomas John. "Nutrient limitation of marine phytoplankton". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e250879e-131e-406a-a3cb-571e00dc0c81.
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Phytoplankton across the majority of the world’s oceans are thought to be limited by the availability of either nitrate or iron (Fe). However, the spatial resolution of experiments confirming this is low. Two thesis chapters present the results of bottle enrichment experiments at high spatial resolution across (i) the South Subtropical Convergence (SSTC) in the South Atlantic, and (ii) the Scotia Sea-Drake Passage sector of the Southern Ocean. These studies have added detail to the boundaries of limiting nutrients in these regions. Patterns of Fast Repetition Rate fluorometry (FRRf) derived parameters, physiological regulation of these parameters including influences of community structure, and the environmental controls driving them are analysed. Given its role as an essential micronutrient, there has been much effort in constraining potential sources of bioavailable Fe to the ocean, with one such source receiving recent interest: erupted ash from volcanoes. Bottle-scale ash-incubation experiments alongside conventional iron additions and laboratory ash-leaching experiments were conducted, the results of which suggest phytoplankton would respond strongly to ash deposition in the High Nitrate, Low Chlorophyll (HNLC) areas of the Southern Ocean. Particularly notable was the evidence these experiments provided for potential (co-)limitation of phytoplankton in these waters by the micronutrient manganese. The first three chapters of this thesis highlight a number of biogeochemical implications of trace metal stress, particularly that of Fe stress. Therefore, the ability to map the oceanographic extent of Fe-stressed regions using remote sensing would represent a particularly useful advance in marine biogeochemistry. Theoretically it could be possible to map Fe stress from space using satellite images of chlorophyll fluorescence, yet there are important uncertainties that need to be addressed before this can be carried out. In particular, a better understanding of the midday non-photochemical quenching driven reductions in chlorophyll fluorescence occurring at the time satellite images are captured is required. Analysis of over 200 non-photochemical quenching experiments collected over three research cruises, has allowed us to explore non-photochemical quenching and its relevance for using sunlight induced chlorophyll fluorescence to assess broad patterns of Fe stress. Our results have confirmed that satellite fluorescence quantum yields have the potential to reveal broad regions of Fe stress, however a dynamic non-photochemical quenching correction derived from our experiments and analysis was necessary to achieve this.
9
Charlton, Fergus. "Remote sensing of freshwater phytoplankton". Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/21140.
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This study researches the potential for using hyperspectral remote sensing to identify the phytoplanktonic composition of a freshwater bloom. Six novel analytical techniques were developed to identify phytoplankton class from reflectance spectra. These techniques offer the water manager a variety of means to identify the dominant phytoplankton class in a target water body. Identification of phytoplankton class is possible because certain photosynthetic pigments contained within phytoplankton cells are taxonomically significant, being indicative of a particular class. The detection of these pigments can be used to identify the presence of a particular phytoplanktonic class in an aquatic system. It is possible to identify these pigments using optical methods because they exhibit unique spectral absorption signatures. Such pigment absorption features are manifest in the composite reflectance signature from water bodies as measured by remote sensing instruments. However, due to the presence of the spectral features from other photosynthetic pigments and the other optically active components of water bodies, extracting from reflectance spectra the spectral information pertaining to individual class marker pigments can be difficult. The phytoplankton class identification techniques presented in this study were developed using absorption and reflectance spectra from pure cultures of phytoplankton. The reflectance spectra were measured in the controlled environment of a laboratory based experimental tank designed for this study. The class identification techniques were tested on field and airborne reflectance spectra measured from a eutrophic inland lake.
10
Malick, Lisa A. "Light quality and phytoplankton viability". [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000350.
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Sackmann, Brandon S. "Remote Assessment of 4-D Phytoplankton Distributions off the Washington Coast". Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/SackmannBS2007.pdf.
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Moore, Timothy S. "Dynamics of phytoplankton community composition in the western Gulf of Maine". Restricted access (UM), 2008. http://libraries.maine.edu/gateway/oroauth.asp?file=orono/etheses/37803141.pdf.
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These (Ph.D.)--University of New Hampshire, 2008.Title from PDF title page. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (leaves 145-157). Also issued in print.
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Mouw, Colleen Beckmann. "Bio-optical and remote sensing investigation of phytoplankton community size structure /". View online ; access limited to URI, 2009. http://digitalcommons.uri.edu/dissertations/AAI3368002.
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Johnson, Virginia L. "Primary productivity by phytoplankton : temporal, spatial and tidal variability in two North Carolina tidal creeks /". Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/johnsonv/virginiajohnson.pdf.
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Hardenbicker, Paulin. "Phytoplankton dynamics in two large rivers:". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-147859.
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This study addresses the regulation of large river phytoplankton by climate-related drivers with the help of three different approaches, i.e. analyses of long-term data and spatial dynamics (longitudinal samplings) as well as mathematical modeling. The central hypothesis is that discharge has a dominant role among climate-related variables which strongly alters phytoplankton biomass development. A multi-factorial statistical analysis on the basis of long-term data (1990 – 2009; 1994 – 2009) from two measuring stations of the rivers Rhine and Elbe revealed that discharge conditions and light availability were the main driving forces regulating phytoplankton spring bloom dynamics. For the Rhine, a trend towards an earlier occurrence of the spring bloom event and a decrease in seasonal mean phytoplankton biomass could be detected, whereas for the Elbe no shift in the timing of the spring bloom and a tendency towards increasing seasonal mean phytoplankton biomass was found. Longitudinal sampling campaigns served to analyze the spatial plankton development on a short-term scale. River-internal growth and loss processes, as well as import mediated by tributaries were examined. Four longitudinal profiles were realized at different seasons in recent years (2009 – 2011) and it was revealed that tributaries mainly had a diluting impact on plankton densities in the Elbe and provided an additional import of phyto- and zooplankton densities in the Rhine. In the present study, high bivalve abundances were detected in the Rhine, probably leading to river-internal losses of phytoplankton which could compensate phytoplankton production resulting in low phytoplankton concentrations. In the Elbe, low abundances of bivalves and a low benthic grazing pressure prevailed. On the other hand, an unusually low discharge event in spring 2011 in the Rhine demonstrated that loss processes can at times be superimposed by strong phytoplankton production leading to extremely high phytoplankton biomasses and chlorophyll a values. Hence, despite the observed long-term trend of decreasing chlorophyll values in the last two decades, extreme environmental conditions can provoke regime shifts with exceptional phytoplankton mass developments. To assess the potential impacts of future climate change on water quality, the water quality simulation model QSim was used to establish a model for the free-flowing part of the Rhine. The modeling approach was implemented by changing the hydrological and climatologic input data according to different climate projections for the near (2021 – 2050) and the far future (2071 – 2100). The model results indicated a weak response of phytoplankton biomass in the Rhine towards altered climatic conditions, including discharge reductions and water temperature increases. The study suggests that changes in discharge rather than water temperature mediate climate change effects on large river phytoplankton. However, the effects are river specific as a consequence of system specific differences in main control mechanisms (e.g. ‘bottom-up’ versus ‘top-down’)Anhand von drei verschiedenen Ansätzen analysiert die vorliegende Arbeit die Regulierung von Phytoplankton in großen Flüssen durch klimabedingte Faktoren: Auswertung von Langzeitdaten, räumliche Dynamik (fließzeitkonforme, longitudinale Beprobungen) und mathematische Modellierung. Die zentrale Hypothese ist, dass Abfluss eine dominante Rolle unter den klimabedingten Faktoren spielt und die Phytoplanktonbiomasse stark beeinflusst. Eine multifaktorielle statistische Analyse basierend auf Langzeitdaten (1990 – 2009; 1994 –2009) von zwei Stationen der Flüsse Rhein und Elbe zeigten, dass hauptsächlich Abflussbedingungen und Lichtverfügbarkeit die Antriebskräfte bei der Regulierung der Phytoplanktonfrühjahrsblüte darstellten. Während sich am Rhein ein Trend hin zu einem früheren Auftreten der Frühjahrsblüte und einer Abnahme der mittleren Phytoplankton-biomasse während der Vegetationsperiode zeigte, konnte für die Elbe keine zeitliche Verschiebung der Frühjahrsblüte festgestellt werden und mittlere Phytoplanktonbiomassen zeigten hier eine steigende Tendenz. Longitudinale Fließzeitbeprobungen dienten zur Analyse der kurzfristigen räumlichen Entwicklung des Planktons. Interne Produktions- und Verlustprozesse, sowie der Eintrag durch Zuflüsse wurden untersucht. Vier longitudinale Profile wurden zu unterschiedlichen Jahreszeiten der letzten Jahre (2009 – 2011) realisiert und es wurde gezeigt, dass die Nebenflüsse der Elbe vorwiegend einen Verdünnungseffekt auf die Planktondichten des Hauptstromes hatten, während sie für den Rhein einen wichtigen zusätzlichen Eintrag von Phyto- und Zooplankton darstellten. In der vorliegenden Arbeit wurden hohe Muscheldichten im Rhein gefunden, die möglicherweise zu hohen internen Planktonverlusten durch Fraß beigetragen haben, und somit zu niedrigen Phytoplankton-konzentrationen geführt haben könnten. In der Elbe waren die Muscheldichten dagegen gering und somit war auch der benthische Fraßdruck niedriger. Auf der anderen Seite zeigte ein ungewöhnlich niedriges Abflussereignis im Frühjahr 2011 am Rhein, dass diese Verlustprozesse zeitweise von starker Phytoplanktonproduktion überlagert werden können und dadurch extrem hohe Phytoplanktonbiomassen und Chlorophyllwerte entstehen können. Demzufolge können trotz der Beobachtung eines langfristigen abnehmenden Trends in den Chlorophyllgehalten während der letzen zwei Jahrzehnte extreme Umweltbedingungen einen Regime-shift mit außergewöhnlichen Massenentwicklungen des Phytoplanktons hervorrufen. Um den möglichen Einfluss des zukünftigen Klimawandels auf die Gewässergüte abzuschätzen, wurde mithilfe des Gewässergütesimulationsmodells QSim ein Modell für den frei fließenden Abschnitt des Rheins erstellt. Für den Modellierungsansatz wurden die hydrologischen und klimatologischen Eingangsdaten entsprechend der verschiedenen Klimaprojektionen für die nahe (2021 – 2050) und ferne Zukunft (2071 – 2100) verändert. Die Modellergebnisse zeigten, dass sich Änderungen in den klimatischen Bedingungen, einschließlich Abflussreduktion und Wassertemperaturanstieg, nur geringfügig auf die Phytoplankton¬biomasse des Rheins auswirkten. Die vorliegende Arbeit deutet darauf hin, dass Klimawandeleffekte eher durch Änderungen der Abflussverhältnisse auf das Phytoplankton in großen Flüssen wirken als durch Änderungen der Wassertemperatur. Der Effekt ist jedoch flusssystemspezifisch, da die Auswirkungen von systemspezifischen Unterschieden in den Hauptkontrollmechanismen gesteuert werden (z.B. ‚Bottom-up’ versus ‚Top-down’)
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Regel, Rudi Herbert. "Phytoplankton and turbulence at selected scales". Title page, contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phr333.pdf.
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Bibliography: leaves 309-329. This thesis attempts to contribute to the understanding of how turbulence affects phytoplankton in freshwater systems, focussing on the temporal and spatial scales in phytoplankton dynamics ranging from photochemistry in the surface mixed layer to a small-scale shear and growth to intra-seasonal changes in community composition in a lake subject to high disturbances.
17
Chan, Terence. "Phytoplankton dynamics in a seasonal estuary". University of Western Australia. Centre for Water Research, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0089.
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[Truncated abstract] The Swan River is a highly seasonal estuary in the south-west of Western Australia. Salinity may vary from fresh to marine at various times throughout the estuary, depending mostly on the intensity of freshwater discharge. There are occasional problematic dinoflagellate blooms which have spurred investigation of the dynamics of the phytoplankton community. The objective of this research was to examine how phytoplankton biomass and species' successions are influenced by the multiple variables in the aquatic ecosystem, and, if possible, to determine the dominant factors ... Comparisons of phytoplankton nutrient limitation simulations with experimental observations from field bioassays require further investigation, but reinforce findings that nutrients may only limit phytoplankton biomass when there is a convergence of favourable hydrological and hydrodynamic conditions. The Swan River estuary has undergone substantial hydrological modifications from pre-European settlement. Land clearing has increased freshwater discharge up to 5- fold, while weirs and reservoirs for water supply have mitigated this increase and reduced the duration of discharge to the estuary. Nutrient loads have increased approximately 20-fold from pre-European levels. The individual and collective impacts of these hydrological changes on the Swan River estuary were examined using the hydrodynamic-ecological numerical model. The simulation results indicate that despite increased hydraulic flushing and reduced residence times, increases in nutrient loads are the dominant perturbation, producing increases in the frequency and biomass of blooms by both estuarine and freshwater phytoplankton. By comparison, changes in salinity associated with altered seasonal freshwater discharge have a limited impact on phytoplankton dynamics. Reductions of nutrient inputs into the Swan River estuary from its catchment will provide a long-term improvement in water quality but manipulations of freshwater discharge have the potential to provide a provisional short-term remediation measure allowing at least partial control of phytoplankton bloom potential and eutrophication.
18
Kennaway, Gabrielle M. A. "The population biology of freshwater phytoplankton". Thesis, Bangor University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236909.
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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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See, Jason Holt. "Availability of humic nitrogen to phytoplankton". W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539616848.
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The chemical, physical, and biological factors affecting the bioavailability of humic nitrogen (N) to coastal phytoplankton were examined. Historically, humic substances have largely been considered biologically refractory, and humic-N is though to be unavailable biologically without prior oxidation via photochemical cleavage or remineralization by bacteria. This is due in part to the high aromaticity and low N content of humic substances. This dissertation investigates whether these assumptions are valid, and whether humic substances may be a more important source of N to the coastal phytoplankton community than previously believed. The research consisted of four main parts. First, changes in the structure and N content of humic substances were monitored by forming humics in the laboratory and following the changes in structure and chemical composition as they aged. It was found that as humics age, they become more aliphatic and fulvic-like. It was also determined that the commonly used XAD-8 extraction technique may underestimate the N content of aquatic humics by stripping ammonium (NH4+) from the humic structure. Second, whether or not this underestimation of humic-N has an effect on previously reported rates of photochemical N liberation from humic compounds was investigated. It was found that while the potential for the underestimation of photochemical release exists, previously reported rates are close to correct, largely due to physical and chemical interactions of humic substances with the surrounding environment. Third, the bioavailability of humic-N was examined using a suite of coastal phytoplankton strains. In short, all coastal strains exposed to humic substances could take up humic-N in short-term incubations; an open ocean strain tested did not take up humic-N. Furthermore, younger humics appeared to be more labile than those aged for time periods greater than three months. Finally, the significance of the salinity-mediated release was investigated and found to be a potentially important transport mechanism of NH4 + to the mid-saline regions of the estuary. In conclusion, the combination of chemical, physical, and biological processes occurring in the estuarine and coastal ecosystems suggests that humic substances are highly dynamic, biologically active compounds and not the biologically recalcitrant molecules portrayed in current literature.
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Tozzi, Sasha. "Photobiological studies of Ross Sea phytoplankton". W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539616879.
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The Ross Sea polynya is characterized by high spatial and temporal variability and by an annual cycle of sea ice retreat, water column stratification, large phytoplankton blooms, and months of complete darkness. This region is also highly susceptible to increasingly changing climatic conditions that will significantly affect the hydrography, iron supply, primary production patterns and carbon cycling. This project focused on analyzing how differences in photosynthetic traits between the two major bloom-forming functional groups in the polynya, diatoms and the prymnesiophyte Phaeocystis antarctica, and investigate if these differences can explain their dominance and succession. The study was conducted as part of the Controls on Ross Sea Algal Community Structure (CORSAC) program during two cruises in December 2005-January, 2006, and November-December, 2006. A fast repetition rate fluorometer (FRRF) was used to assess photochemical efficiency on natural phytoplankton assemblages and on monoclonal cultures. Measurements were made on cultures to determinate differences in photorecovery kinetics, as well on a suite of experiments performed to test the effects of temperature, iron, CO2 and micronutrients had on natural assemblages. In addition, FRRF measurements were made on 1,182 discrete samples representative of 98 profiles collected over the two cruises. Phaeocystis antarctica consistently photorecovered faster than the diatoms Pseudo-nitzschia sp., indicating different photosynthetic strategies and ecological niches; in addition, temperature and iron significantly promoted photosynthetic quantum yields, indicating a diffuse iron limitation of the natural assemblages used for the experiments and a high susceptibility to forecasted temperature increases in the region. Experiments also demonstrated that the Ross Sea phytoplankton is capable of maintaining high photosynthetic capacity after extensive periods in the dark. The dominance and successions in the blooms appears to be controlled by a combination of hydrography and in particular by the relative depths of the mixed layer and euphotic zone, as well by the water temperatures and possibly by iron concentrations. Diatom-dominated blooms were found in shallow mixed water layers characterized by higher temperature and fresher waters in the summer in the western part of the polynya, while Phaeocystis antarctica prevailed in colder regions with deeper mixed layer depths in the eastern part of the polynya. The dominance in the bloom significantly affected the relative macronutrient drawdown. Photosynthetic characteristic of natural assemblages were also modeled based on variable fluorescence rapid light curves (RLCs), and photophysiological differences were found between diatoms and Phaeocystis antarctica, with the latter having higher Ek and lower functional absorption cross sections (sigmaPSII) and alpha values, but similar maximum electron transport rates (ETRs). Lastly, correlation between RLC-based modeled photosynthetic rates and 14C based primary production presented some discrepancies due to limitations and differences in methodologies.
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Thompson, Brian P. "Temporal and Spatial Variability of Phytoplankton Biomass in the Damariscotta River Estuary, Maine, USA". Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/ThompsonBP2006.pdf.
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Armstrong, Gary Dale. "Colonies as defence in the freshwater phytoplankton genus Dinobryon (Chrysophyceae)". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24468.
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This thesis addresses the idea that colony formation effectively increases the size of a phytoplankter thereby reducing grazing losses by deterring ingestion by zooplankton. It was initially hypothesized that colonies of Dinobryon (Ochromonadales, Chrysophyceae) deter zooplankton grazers, and that their spring population declined either because of a drop in the mean colony size of the Dinobryon population or from an increase in the abundances of large zooplankton grazers capable of ingesting large colonies.
From January to May 1983 a small dystrophic lake was sampled weekly at three discrete depths at two stations. In the samples collected from one station, two species of Dinobryon, D. cylindricum Imhof and D. diverqens Imhof, as well as all zooplankton species were enumerated and morphometric variables of Dinobryon colonies were measured.
The results showed that, alone, each of the original hypotheses could not account for the population and colony size dynamics of the Dinobryon species present in the lake. A new hypothesis was generated from the results which suggested that Dinobryon colonies minimized grazing losses to small grazers because of increased size and to larger grazers by fragmentation upon capture. Subsequent evaluation of the assumptions of this new hypothesis, using both the original data and new data from the second station, added further support to the hypothesis.Science, Faculty of
Botany, Department of
Graduate
24
Allen, Jason D. "Correlating phytoplankton assemblages with water quality in Illinois lakes and reservoirs : validating models based on historical data /". View online, 2008. http://repository.eiu.edu/theses/docs/32211131464742.pdf.
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Karp-Boss, Lee. "Phytoplankton-flow interactions in relation to cell size and morphology /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11004.
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Hyde, Kimberly Joy Whitman. "Interannual and seasonal phytoplankton variability in Massachusetts Bay from remote and in situ measurements /". View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3248231.
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Lam, Yung-chun Nelson. "Annual distribution of phytoplankton in Tolo Harbour a flow cytometry approach /". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22718874.
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Maurer, Vinzenz. "Die Produktionsbiologie von Bieler- und Neuenburgersee, 1987-1988 : Beziehungen zwischen Nährstoffen, Algen und Crustaceen /". Bern : Selbstverlag, 1992. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Silsbe, Gregory. "Phytoplankton Production In Lake Victoria, East Africa". Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/1231.
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This thesis develops, validates and applies an empirical model that provides the first spatially explicit estimates of gross and net phytoplankton production in Lake Victoria. Gross and net phytoplankton production are in turn used to estimate the maximum sustainable yield (MSY) of Lake Victoria's fishery following an empirical formula and the carbon efficiency transfer method. Chapter 2 presents results from three inshore areas where diurnal and sub-seasonal gross and net phytoplankton production was derived using an adapted version of the phytoplankton production model developed by Fee (1990). Spatial and temporal trends of chlorophyll (chl), PI parameters, the vertical attenuation of PAR (kPAR), Secchi depths (SD) and respiration rates are identified. kPAR and SD are highly correlated to chl within the euphotic zone, as well as to each other. Furthermore, the two PI parameters, PBM and aB, exhibit a strong linear relationship and both decline along an increasing chl gradient, presumably due to increased light-limitation, a taxonomic shift from diatoms to cyanobacteria with increasing chl as well as an increased need for biologically fixed nitrogen. These hypotheses are supported by observed synchronous changes in the PSII:PSI ratio of phytoplankton and changes in the chl-specific attenuation of PAR (kchl). Relationships are also derived between biomass-specific respiration rates (RB) with chl and PBM; similar to PI parameters RB decreases with increasing chl. Owing to these correlative trends, only one parameter is required to estimate gross phytoplankton production through the empirical model developed in this thesis. The empirical model predicts that gross phytoplankton production increases in a near linear fashion between chl of 0 to 10 mg. m-3, begins to flatten out as chl approaches 20 mg. m-3 and then slightly decreases when chl exceeds 40 mg. m-3 where the maximum PPG of 13. 1 g O₂. m-2. day-1 is reached and is in close agreement with a theoretical argument proposed by Talling (1965). Areal respiration and consequently net phytoplankton production are sensitive to chl within the mixed layer as well as mixed layer depths. Overall, the lakewide averages of gross and net phytoplankton production are 9. 68 and 2. 2 g O₂. m-2. day-1 respectively. Significant temporal variability was observed on sub-seasonal scales within the inshore of Lake Victoria, and changes in limnological parameters coincided with changes in water column temperatures in each of the three bays. In Fielding Bay, the availability of meteorological data revealed that strong nocturnal wind events decreased both the water column temperature and chl, while both parameters generally increased in the absence of any such wind event. Lateral exchange of water with deeper areas through strong wind events essentially flushes Fielding Bay causing the observed decreases in both the water column temperature and chl; this hydrodynamic event also influences other limnological parameters according to their respective correlative regression equations with chl. Spatial trends were also observed between inshore areas. The deepest area, Napoleon Gulf, has the lowest values of chl while the shallowest area, Inner Murchison Bay, has the highest chl as the mean depth of a bay sets an approximate upper limit on chl. With respect to diurnal variability, PI parameters decline through the day, kPAR increases over the day and no statistically valid trends were ascertained for chl and RB. Chapter three examined spatial and seasonal patterns of chlorophyll fluorescence, temperature, dissolved oxygen and water transparency from four lakewide cruises. Significant spatial variability of each parameter confirmed that lakewide data is required to generate spatially explicit estimates of phytoplankton production. Complex patterns in the thermal structure during each cruise illustrated that physical processes in Lake Victoria are at times more complex that a previously stated unidirectional hypothesis of warm water in the north and cool water in the south (Spigel and Coulter 1996), and these patterns influence spatial patterns in dissolved oxygen and Secchi depths. Similar to Chapter 2, estimates of chl within the mixed layer were highly correlated to mixed depths, while lakewide averages of chl are lower than previously reported offshore values (Mugidde 1993, 2001).
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Butler, Joanne Elizabeth. "Phytoplankton ecology in a high arctic polynya". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25080.
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Primary production was studied in Fram Sound, part of the Hell Gate-Cardigan Strait polynya, from June to August, 1982. Primary production rates, phytoplankton biomass (chlorophyll α), and water transparency were measured and used in conjunction with modelled solar radiation values to numerically model primary production during this time. The major phytoplankton nutrients were also measured.
Early season chlorophyll α concentrations were low, and the increased light availability due to reduced ice cover in this area did not appear to enhance early season production. Chlorophyll concentrations peaked twice; the first peak occured on 20 July and the
second on 14 August. The mean primary production rate and phytoplankton
biomass were 998 mg C.m⁻² .d⁻¹ and 72 mg chl.m⁻² . This production rate
is higher than that measured in other High Arctic areas.
Nitrogen, phosphorus and silica were essentially homogeneously
distributed during the sampling period and these concentrations varied
little from June to August except during 5 days in late August, when
they decreased by half then returned to previous levels.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Kyewalyanga, Margareth Nabuma. "Spectral dependence of photosynthesis in marine phytoplankton". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24750.pdf.
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Wiegman, Saskia. "Photoenhanced toxicity of azaarenes to marine phytoplankton". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/64908.
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Thomas, Lorraine. "Estimating phytoplankton growth rates from compositional data /". Online version of original thesis, 2008. http://hdl.handle.net/1912/2255.
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Hutchings, Alison Jayne. "Phytoplankton distribution in the River Thames, England". Thesis, Durham University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362137.
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MacCallum, Iain. "Measurement and modelling of phytoplankton light scattering". Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248311.
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Dimier, Celine. "Photoacclimation processes and ecological characteristics of phytoplankton". Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437316.
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Thomas, Lorraine (Lorraine Marie). "Estimating phytoplankton growth rates from compositional data". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43755.
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Thesis (S.M.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008."February 2008."
Includes bibliographical references (p. 133).
I build on the deterministic phytoplankton growth model of Sosik et al. by introducing process error, which simulates real variation in population growth and inaccuracies in the structure of the matrix model. Adding a stochastic component allows me to use maximum likelihood methods of parameter estimation. I lay out the method used to calculate parameter estimates, confidence intervals, and estimated population growth rates, then use a simplified three-stage model to test the efficacy of this method with simulated observations. I repeat similar tests with the full model based on Sosik et al., then test this model with a set of data from a laboratory culture whose population growth rate was independently determined. In general, the parameter estimates I obtain for simulated data are better the lower the levels of stochasticity. Despite large confidence intervals around some model parameter estimates, the estimated population growth rates have relatively small confidence intervals. The parameter estimates I obtained for the laboratory data fell in a region of the parameter space that in general contains parameter sets that are difficult to estimate, although the estimated population growth rate was close to the independently determined value.
by Lorraine Thomas.
S.M.
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Yee, Donald. "Cobalt substitution for zinc in marine phytoplankton". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43289.
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Balbi, David Michael. "Phytoplankton dynamics of the River Nene, England". Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4281/.
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The distribution of suspended algae was investigated in a 69-km length of a small lowland river in the UK, the Nene (annual median discharge at km 91.7 =6 m(^3) s(^-1). Variations in chlorophyll a data collected between 1975 and 1998 by water management organisations at km 91.7 were evaluated against a range of physical and chemical variables. Interpretation was aided by additional sampling between 1993 and 1997.The latter half of the 24-year period had significantly higher temperatures and sunshine-hours and significantly lower ammonium concentrations. Discharge, temperature and sunshine-hours were significant predictors of chlorophyll concentration, particularly between January and June, and spring chlorophyll maxima ranged from 106 to 276 µg L(^-1).Centric diatoms were the most abundant taxa in the main-river and, in the absence of other limiting factors, appeared to be restricted by the availability of silica. There was also evidence that the centric diatoms suffered from severe parasitism. Inter-year phytoplankton abundance was most variable in the summer, and years with abundant submerged macrophytes had particularly low phytoplankton numbers. Spring phytoplankton peaks occurred earlier and had smaller amplitude at downstream sites than those further upstream. Average spring chlorophyll concentrations (April - June) increased significantly between km 22.4 and km 43.9, thereafter remaining high to km 91.7. Spatial trends were attributed to changes in channel morphology, retention time, dead zones, longitudinal variations in current velocity, temperature and silica limitation. An appraisal of the Utermöhl method of counting phytoplankton was made and a new technique proposed, called 'spaced fields'. The spaced fields method accurately identified small changes in phytoplankton abundance and was used to identify short-term temporal and small-scale spatial trends in the Nene.
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Bertos-Fortis, Mireia. "Baltic Sea phytoplankton in a changing environment". Doctoral thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-57860.
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Future climate scenarios in the Baltic Sea project increasing sea surface temperature, as well as increasing precipitation and river runoff resulting in decreased salinity. These changes can severely impact the dynamics and function of brackish water communities, specifically phytoplankton. Phytoplankton are a significant source of organic matter to other trophic levels, and some species can be toxic. Their response to future climate conditions is of great relevance for the health of humans and aquatic ecosystems. The aim of this thesis was to assess the potential for climate-induced changes, such as decreasing salinity, to affect phytoplankton dynamics, physiology and chemical profiles in the Baltic Sea. Phytoplankton successional patterns in the Baltic Proper consist of a spring bloom where diatoms and dinoflagellates co-occur and a summer bloom dominated by filamentous/colonial cyanobacteria. The consensus is that future warmer conditions will promote filamentous/colonial cyanobacteria blooms. This thesis shows that phytoplankton biomass in the spring bloom was lower in years with milder winters compared with cold winters. This suggests that in terms of annual carbon export to higher trophic levels, loss of biomass from the spring bloom is unlikely to be compensated by summer cyanobacteria. High frequency sampling of phytoplankton performed in this thesis revealed a strong relationship between the dynamics of pico- and filamentous cyanobacteria. Large genetic diversity was found in cyanobacterial populations with high niche differentiation among the same species. At community level, high temperature and low salinity were the main factors shaping the summer cyanobacterial composition. These conditions may promote the predominance of opportunistic filamentous cyanobacteria, e.g. Nodularia spumigena. This species produces various bioactive compounds, including non-ribosomal peptides such as the hepatotoxin nodularin. In this work, N. spumigena subpopulations evolved different physiological strategies, including chemical profiles, to cope with salinity stress. This high phenotypic plasticity ensures survival in future climate conditions. Under salinity stress, some subpopulations displayed shorter filaments as a trade-off. This indicates that the future freshening of the Baltic Sea may promote grazing on filamentous cyanobacteria and modify carbon flows in the ecosystem. In this thesis, Baltic N. spumigena chemotypes and genotypes grouped into two main clusters without influence of geographical origin. Thus, chemical profiling can be used to explore conspecific diversity in closely genetically related N. spumigena subpopulations. Overall, this thesis has significantly expanded the knowledge on phytoplankton community and population responses to short- and long-term environmental changes, relevant to project the impacts of future climate conditions in the Baltic Sea.
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Crawfurd, Katharine. "Marine phytoplankton in a high CO2 world". Thesis, University of Dundee, 2010. https://discovery.dundee.ac.uk/en/studentTheses/82b46f33-e436-4eff-9862-e464f2761dca.
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Marine phytoplankton is responsible for ~50% of global primary productivity, it supports the oceanic food web and affects biogeochemical cycles. I participated in a large mesocosm experiment that observed altered community structure and carbon drawdown in response to increased CO2. There was a 27% reduction in community primary production at the peak of an Emiliania huxleyi-dominated bloom in mesocosms initially at 760 ppm CO2 compared to present day pCO2. There were changes in community structure but not dominance; Synechococcus and large pico-eukaryote abundances were reduced by ~60%, E. huxleyi was reduced by ~50%. A number of E. huxleyi strains persisted throughout the experiment in both treatments and no malformation or significant change in lith size occurred at increased CO2. In a second field experiment in the oligotrophic ocean off the Canary Islands, 760 ppm pCO2 did not change community structure or cell division rates of Synechococcus, Prochlorococcus or pico-eukaryotes.In laboratory experiments, I maintained the diatom, Thalassiosira pseudonana CCMP1335 at 760 ppm and present day pCO2 for ~100 generations in gas equilibrated continuous cultures – one of the longest experiments that has been attempted to investigate the effect of increased CO2 on marine phytoplankton. No clear evidence of adaptation or acclimation to increased CO2 was found, neither were there consistent changes in transcription of RuBisCO or carbonic anhydrase genes. Non-calcified E. huxleyi CCMP1516 and calcified CCMP371 grown in gas equilibrated semi-continuous cultures for several weeks showed no change in cell division rate at 760 ppm CO2. An understanding of the underlying changes in communities is required for modelling responses to increasing CO2, molecular tools may prove useful for this task. The strong community response in the mesocosms shows that rising atmospheric CO2 can greatly affect phytoplankton productivity and biogeochemical cycling.
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Brereton, Ashley. "Phytoplankton aggregations in a turbulent boundary layer". Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/15833/.
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Phytoplankton aggregations come in a wide range of space and time scales and, as such, simulating such behavior is computationally restrictive. I present a Large-eddy simulation of the upper mixed layer, resolving scales of o(1m). I then show how aggregations are promoted by nutrient upwellings (something which macroscale models struggle to emulate), facilitated primarily by Langmuir circulations. I then demonstrate how certain levels of turbulent mixing encourage planktonic thin layering, a phenomenon which is widely observed.
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Dustman, John M. "Carbon sequestration by Iron seeding of phytoplankton /". May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Dyhrman, Sonya T. "Cellular markers of phosphate stress in phytoplankton /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035410.
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Baker, Cynthia Fay. "Phytoplankton in Mt. St. Helens Lakes, Washington". PDXScholar, 1995. https://pdxscholar.library.pdx.edu/open_access_etds/5017.
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Phytoplankton communities in fifteen lakes in the Mt. St. Helens area were surveyed to assess the abundance and species present. Eleven of the lakes were inside the blast zone of the 1980 eruption and four were located outside the blast zone as a comparison. The hypothesis is that lakes will cluster together based on the algal species present and that some algae will be correlated with certain environmental conditions. A cluster analysis was performed to determine if the lakes would group together based on algal abundance. There did not appear to be any distinct clustering among the study lakes, but this analysis did help to sort out some similarities of algal species present between lakes. It demonstrated that the lakes outside the blast zone were not functional as control lakes because they were very different from the blast-zone lakes. They had different assemblages of algae and their origin was so different from the blast-zone lakes that there was little overlap between them. The factor analysis was applied to determine the relationships between environmental variables and phytoplankton. The hypothesis is that certain algae are associated with each other and with identifiable environmental factors. Factor analysis should detect these patterns. The factors represent some condition in the environment but the analysis would be virtually meaningless unless these conditions can be recognized and the factors named. From the factor analysis alone, I could not name the factors but returned to the task after the canonical correlation analysis was performed. The canonical correlation analysis gave some clues to identify the environmental conditions that exert control on these algae. The most useful statistical technique used in this study was the canonical correlation analysis. This analysis is a useful tool in community ecology studies where species-environment relationships can be inferred from community composition and environmental data. The environmental data used was nutrient and light attenuation present at the time the phytoplankton samples were taken. From this analysis I summarized a list of algae and with what environmental conditions that they are associated. Trophic state categories were assigned to the lakes from a trophic state index based on phytoplankton biovolume.
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Roncarati, Francesca <1977>. "Phytoplankton physiological responses under changing environmental conditions". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/541/1/roncarati_francesca_tesi.pdf.
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Roncarati, Francesca <1977>. "Phytoplankton physiological responses under changing environmental conditions". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/541/.
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Van, Wijk Kim. "The effect of organic carbon and nitrogen additions on inorganic nitrogen uptake by phytoplankton and bacteria". Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/18342.
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Bibliography: pages 76-89.This study examines the effects of enrichment with organic carbon and nitrogen on inorganic nitrogen partitioning between phyto- and bacterio- plankton. Strongly preferential uptake of ammonium over nitrate was observed by both the phytoplanktonic and bacterial fractions, with RPINH4 values typically between 1 and 5. The bacterial fraction ( <0.8μm) was found to be responsible for as much as 48-75% of community uptake of ammonium; while the netplanktonic fraction was observed to take up approximately 50% of intact community uptake of nitrate. The addition of amino acids appeared to mediate bacterial competition for ammonium, indicating their preference for DON as a nitrogen source and allowing increased ammonium uptake by the nanoplanktonic fraction. The effect of glucose enrichment was complicated by the presence of protozoans, which appeared to be indirectly responsible for decreased ammonium uptake due to depletion of this substrate in the presence of added glucose. The nanoplankton appeared to be responsible for the least nitrogen uptake with respect to biomass, indicating that they may have been subject to competition pressure from both the bacterial and netplanktonic fractions.
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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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Tang, Senming, i 唐森銘. "Seasonal changes in phytoplankton species composition at Port Shelter,Hong Kong, China (1998-1999)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B29867976.
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