Littérature scientifique sur le sujet « Phytoplankton light absorption »
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Articles de revues sur le sujet "Phytoplankton light absorption"
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Duarte, C. M., S. Agustí et J. Kalff. « Particulate light absorption and the prediction of phytoplankton biomass and planktonic metabolism in northeastern Spanish aquatic ecosystems ». Canadian Journal of Fisheries and Aquatic Sciences 57, no 1 (1 janvier 2000) : 25–33. http://dx.doi.org/10.1139/f99-184.
Texte intégralRésumé :
Examination of particulate light absorption and microplankton metabolism in 36 northeastern Spanish aquatic ecosystems, ranging from alpine rivers to inland saline lakes and the open Mediterranean Sea, revealed the existence of general relationships between particulate light absorption and the biomass of phytoplankton and microplankton metabolism. The particulate absorption spectra reflected a dominance of nonphotosynthetic, likely detrital, particles in rivers and a dominance of phytoplankton in coastal lagoons. There was a strong relationship between the light absorbed by phytoplankton and the chlorophyll a (Chl a) concentration of the systems, which indicated an average (±SE) Chl a specific absorption coefficient of 0.0233 ± 0.0020 m2·mg Chl a-1 for these widely diverse systems. Chl a concentration was a weaker predictor of the total particulate light absorption coefficient, pointing to an important role of nonphytoplanktonic particles in light absorption. Gross production was very closely related to the light absorption coefficient of phytoplankton, whereas community respiration was strongly correlated with the total particulate light absorption coefficient, indicating the optical signatures of sestonic particles to be reliable predictors of planktonic biomass and metabolism in aquatic ecosystems.
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Asselot, Rémy, Frank Lunkeit, Philip B. Holden et Inga Hense. « Climate pathways behind phytoplankton-induced atmospheric warming ». Biogeosciences 19, no 1 (14 janvier 2022) : 223–39. http://dx.doi.org/10.5194/bg-19-223-2022.
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Abstract. We investigate the ways in which marine biologically mediated heating increases the surface atmospheric temperature. While the effects of phytoplankton light absorption on the ocean have gained attention over the past years, the impact of this biogeophysical mechanism on the atmosphere is still unclear. Phytoplankton light absorption warms the surface of the ocean, which in turn affects the air–sea heat and CO2 exchanges. However, the contribution of air–sea heat versus CO2 fluxes in the phytoplankton-induced atmospheric warming has not been yet determined. Different so-called climate pathways are involved. We distinguish heat exchange, CO2 exchange, dissolved CO2, solubility of CO2 and sea-ice-covered area. To shed more light on this subject, we employ the EcoGEnIE Earth system model that includes a new light penetration scheme and isolate the effects of individual fluxes. Our results indicate that phytoplankton-induced changes in air–sea CO2 exchange warm the atmosphere by 0.71 ∘C due to higher greenhouse gas concentrations. The phytoplankton-induced changes in air–sea heat exchange cool the atmosphere by 0.02 ∘C due to a larger amount of outgoing longwave radiation. Overall, the enhanced air–sea CO2 exchange due to phytoplankton light absorption is the main driver in the biologically induced atmospheric heating.
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Agustí, Susana. « Allometric Scaling of Light Absorption and Scattering by Phytoplankton Cells ». Canadian Journal of Fisheries and Aquatic Sciences 48, no 5 (1 mai 1991) : 763–67. http://dx.doi.org/10.1139/f91-091.
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Examination of the allometric scaling of light absorption (acell) and scattering (bcell) by 28 phytoplankton species showed that light absorption is scaled to the cross-sectional area of the cells (log acell (square micrometres per cell) = −1.06 + 2.32 log d (micrometres)) whereas light scattering is scaled to their volume (log bcell (square micrometres per cell) = −1.09 + 3.45 log d (micrometres)). The scaling of light absorption to the cross-sectional area of algal cells is explained by a decrease in intracellular chlorophyll a concentration as cell size increases, thereby avoiding inefficient light capture by photosynthetic pigments. The scaling of light scattering to cell volume conforms to the general theory for large particles (Mie theory). Light absorption by phytoplankton cells, unlike light scattering, deviates from that of nonliving particles because of the covariation between pigment content and cell size that help prevent self-shading.
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Bracher, A., M. Vountas, T. Dinter, J. P. Burrows, R. Röttgers et I. Peeken. « Quantitative observation of cyanobacteria and diatoms from space using PhytoDOAS on SCIAMACHY data ». Biogeosciences Discussions 5, no 6 (28 novembre 2008) : 4559–90. http://dx.doi.org/10.5194/bgd-5-4559-2008.
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Abstract. In this study the technique Differential Optical Absorption Spectroscopy (DOAS) has been adapted for the retrieval of the absorption and biomass of two major phytoplankton groups (PhytoDOAS) from data of the satellite sensor Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). SCIAMACHY measures back scattered solar radiation in the UV-Vis-NIR spectral region with a high spectral resolution (0.2 to 1.5 nm). In order to identify phytoplankton absorption characteristics in SCIAMACHY data in the range of 430 to 500 nm, phytoplankton absorption spectra measured in-situ during two different RV "Polarstern" expeditions were used. The two spectra have been measured in different ocean regions where different phytoplankton groups (cyanobacteria and diatoms) dominated the phytoplankton composition. Results show clearly different absorption characteristics of the phytoplankton groups in the SCIAMACHY spectra. Globally distributed pigment concentrations for these characteristic phytoplankton groups for two monthly periods (February–March 2004 and October–November 2005) were derived from these differential absorptions by including the information of the sensor's optical paths within the water column (i.e. light penetration depth) according to Vountas et al. (2007) derived from DOAS fits of inelastic scattering. The satellite retrieved information on cyanobacteria and diatoms distribution matches well the concentrations measured at collocated water samples with HPLC technique and concentrations derived from the global model analysis with the NOBM model (Gregg et al., 2003; Gregg and Casey, 2007). Identifying quantitative distribution of key phytoplankton groups from space allow to distinguish various biogeochemical provinces and will be of great importance for the global modelling of marine ecosystem and biogeochemical cycles addressing climate changes in the oceanic biosphere.
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Churilova, Tatiana, Natalia Moiseeva, Elena Skorokhod, Tatiana Efimova, Anatoly Buchelnikov, Vladimir Artemiev et Pavel Salyuk. « Parameterization of Light Absorption of Phytoplankton, Non-algal Particles and Coloured Dissolved Organic Matter in the Atlantic Region of the Southern Ocean (Austral Summer of 2020) ». Remote Sensing 15, no 3 (20 janvier 2023) : 634. http://dx.doi.org/10.3390/rs15030634.
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Climate affects the characteristics of the Southern Ocean ecosystem, including bio-optical properties. Remote sensing is a suitable approach for monitoring a rapidly changing ecosystem. Correct remote assessment can be implemented based on a regional satellite algorithm, which requires parameterization of light absorption by all optically active components. The aim of this study is to analyse variability in total chlorophyll a concentration (TChl-a), light absorption by phytoplankton, non-algal particles (NAP), coloured dissolved organic matter (CDOM), and coloured detrital matter (CDM = CDOM+NAP), to parameterize absorption by all components. Bio-optical properties were measured in the austral summer of 2020 according to NASA Protocols (2018). High variability (1–2 orders of magnitude) in TChl-a, absorption of phytoplankton, NAP, CDOM, and CDM was revealed. High variability in both CDOM absorption (uncorrelated with TChl-a) and CDOM share in total non-water absorption, resulting in a shift from phytoplankton to CDOM dominance, caused approximately twofold chlorophyll underestimation by global bio-optical algorithms. The light absorption of phytoplankton (for the visible domain in 1 nm steps), NAP, CDOM, and CDM were parametrized. Relationships between the spectral slope coefficient (SCDOM/SCDM) and CDOM (CDM) absorption were revealed. These results can be useful for the development of regional algorithms for Chl-a, CDM, and CDOM monitoring in the Southern Ocean.
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Liew, S. C., C. K. Choo, J. W. M. Lau, W. S. Chan et T. C. Dang. « Monitoring water quality in Singapore reservoirs with hyperspectral remote sensing technology ». Water Practice and Technology 14, no 1 (10 janvier 2019) : 118–25. http://dx.doi.org/10.2166/wpt.2018.119.
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Abstract In this work, algorithms were developed for retrieving water quality parameters related to Singapore's reservoirs. The main constituents that affect the water reflectance (WR) – i.e. proportion of incident light reflected from the surface of water bodies after removing the surface glint component – are the suspended particles, phytoplankton and coloured dissolved organic matter (CDOM). The existing absorption spectrum model for phytoplankton in seawater is not accurate for the phytoplankton types that exist in the fresh water environment. The phytoplankton absorption spectrum was modelled by a series of Gaussian peaks from 400 to 750 nm. The peak strengths were dynamically derived from the WR measured. The phytoplankton absorption model is incorporated into a semi-empirical WR model for retrieving the absorption and backscattering coefficients of water components such as suspended sediments, CDOM and phytoplankton. The chlorophyll-a concentration and water turbidity estimated using this model correlate well with field sampling measurements, with coefficients of determination (R2) exceeding 0.8.
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Brunelle, Corinne B., Pierre Larouche et Michel Gosselin. « Variability of phytoplankton light absorption in Canadian Arctic seas ». Journal of Geophysical Research : Oceans 117, no C9 (3 août 2012) : n/a. http://dx.doi.org/10.1029/2011jc007345.
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Kraus, Cleber Nunes, Daniel Andrade Maciel, Marie Paule Bonnet et Evlyn Márcia Leão de Moraes Novo. « Phytoplankton Genera Structure Revealed from the Multispectral Vertical Diffuse Attenuation Coefficient ». Remote Sensing 13, no 20 (14 octobre 2021) : 4114. http://dx.doi.org/10.3390/rs13204114.
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The composition of phytoplankton and the concentration of pigments in their cells make their absorption and specific absorption coefficients key parameters for bio-optical modeling. This study investigated whether the multispectral vertical diffuse attenuation coefficient of downward irradiance (Kd) gradients could be a good framework for accessing phytoplankton genera. In situ measurements of remote sensing reflectance (Rrs), obtained in an Amazon Floodplain Lake (Lago Grande do Curuai), were used to invert Kd, focusing on Sentinel-3/Ocean and Land Color Instrument (OLCI) sensor bands. After that, an analysis based on the organization of three-way tables (STATICO) was applied to evaluate the relationships between phytoplankton genera and Kd at different OLCI bands. Our results indicate that phytoplankton genera are organized according to their ability to use light intensity and different spectral ranges of visible light (400 to 700 nm). As the light availability changes seasonally, the structure of phytoplankton changes as well. Some genera, such as Microcystis, are adapted to low light intensity at 550–650 nm, therefore high values of Kd in this range would indicate the dominance of Microcysts. Other genera, such as Aulacoseira, are highly adapted to harvesting blue-green light with higher intensity and probably grow in lakes with lower concentrations of colored dissolved organic matter that highly absorbs blue light (405–498). These findings are an important step to describing phytoplankton communities using orbital data in tropical freshwater floodplains. Furthermore, this approach can be used with biodiversity indexes to access phytoplankton diversity in these environments.
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Wang, S. Q., J. Ishizaka, H. Yamaguchi, S. C. Tripathy, M. Hayashi, Y. J. Xu, Y. Mino, T. Matsuno, Y. Watanabe et S. J. Yoo. « Influence of the Changjiang River on the light absorption properties of phytoplankton from the East China Sea ». Biogeosciences 11, no 7 (3 avril 2014) : 1759–73. http://dx.doi.org/10.5194/bg-11-1759-2014.
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Abstract. Phytoplankton light absorption properties were investigated at the surface and subsurface chlorophyll a maximum (SCM) layer in the East China Sea (ECS), a marginal sea which is strongly influenced by the Changjiang discharge in summer. Results from ECS were compared with those from the Tsushima Strait (TS) where the influence of Changjiang discharge is less. The probable controlling factors, packaging effect (cell size) and pigment composition of total chlorophyll a (Tchl a)-specific absorption coefficient (aph*(λ)) were examined by the corresponding measurements of pigments identified by high-performance liquid chromatography. We observed distinct phytoplankton size structure and thereby absorption properties between ECS and TS. At the surface, mixed populations of micro-, nano- and pico-phytoplankton were recorded in ECS while pico-phytoplankton dominated in TS, generating a lower average aph*(λ) in ECS than in TS. Within SCM, average aph*(λ) was higher in ECS than in TS because of the dominance of nano- and micro-phytoplankton in ECS and TS, respectively. By pooling surface and SCM samples, we found regular trends in phytoplankton size-fraction versus Tchl a; and correlations between aph*(λ) and Tchl a consistent with previous observations for the global ocean in TS but not in ECS. In ECS phytoplankton size-fraction was not correlated with Tchl a, which consequently caused poor relationships between aph*(λ) and Tchl a. The abnormal values mainly originated from the surface low-salinity waters and SCM waters beneath them. At high Tchl a, aph*(λ) of these samples was substantially higher compared to the values in TS and from the global regressions, which was attributable to the lower micro-phytoplankton fraction, and higher nano- and/or pico-phytoplankton fractions in ECS. These observations indicated that the distinct light absorption properties of phytoplankton in ECS were possibly influenced by the Changjiang discharge. Our findings imply that general bio-optical algorithms proposed based on the correlations between aph*(λ) and Tchl a or the patterns in size-fraction versus Tchl a are not applicable in ECS, and need to be carefully considered when using these general algorithms in river-influenced regions.
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Behrenfeld, M. J., T. K. Westberry, E. S. Boss, R. T. O'Malley, D. A. Siegel, J. D. Wiggert, B. A. Franz et al. « Satellite-detected fluorescence reveals global physiology of ocean phytoplankton ». Biogeosciences Discussions 5, no 6 (5 novembre 2008) : 4235–70. http://dx.doi.org/10.5194/bgd-5-4235-2008.
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Abstract. Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we use satellite-based fluorescence measurements to evaluate light-absorption and energy-dissipation processes influencing phytoplankton light use efficiency and demonstrate its utility as a global physiological indicator of iron-limited growth conditions. This new tool provides a path for monitoring climate-phytoplankton physiology interactions, improving descriptions of light use efficiency in ocean productivity models, evaluating nutrient-stress predictions in ocean ecosystem models, and appraising phytoplankton responses to natural iron enrichments or purposeful iron fertilizations activities.
Thèses sur le sujet "Phytoplankton light absorption"
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Drzewianowski, Andrea F. « Temporal Changes in Phytoplankton Variable Fluroescence (FV/FM) and Absorption as a Result of Daily Exposure to High Light ». Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/DrzewianowskiAF2008.pdf.
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Du, Chunzi. « Autonomous optical measurements in Bayboro Harbor (Saint Petersburg, Florida) ». [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001384.
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Cannizzaro, Jennifer P. « Detection and Quantification of Karenia brevis Blooms on the West Florida Shelf from Remotely Sensed Ocean Color Imagery ». [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000257.
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Bucci, André Francisco. « Efeitos de morfotipos do fitoplâncton no comportamento espectral da absorção da luz, e possíveis implicações para a determinação de carbono particulado por sensoriamento remoto ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/21/21134/tde-09042014-163745/.
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O conhecimento da estrutura da comunidade fitoplanctônica depende de estimativas robustas de biomassa e de como variam suas taxas de absorção de luz. Assim, é essencial descrever a relação entre grupos taxonômicos e seus morfotipos. Este trabalho investigou a influência da forma do fitoplâncton, por meio de sua razão S/V no coeficiente de absorção de luz. Comunidades fitoplanctônica de plataforma continental foram detalhadas taxonomicamente e categorizada como morfotipos para o cálculo de biomassa fitoplanctônica, razão S/V e tamanho médio, e relações com o coeficiente de absorção de luz foram exploradas. A razão Carbono:Clorofila-a variou entre a superfície e máximo de fluorescência, enquanto a biomassa permaneceu constante, sendo diatomáceas e dinoflagelados os principais grupos formadores de biomassa. Observamos morfotipos exclusivos a um dado grupo taxonômico, contudo, os intervalos de S/V são compartilhados entre grupos taxonômicos e entre morfotipos. A conversão entre biovolume e biomassa deve incorporar informações taxonômicas. A S/V média da comunidade não mostrou relação com a magnitude da absorção de luz pelo fitoplâncton. Os resultados puderam comprovar a baixa performance de modelos para a determinação de tamanho do fitoplâncton por pigmentos e sugerem que a fotoaclimatação deve ser incorporada para a discriminação bio-ótica do fitoplâncton marinhoAcurate descriptions of phytoplankton community structures depends on reliable estimation of biomass and on the understanding of light absorption. It is crucial to trace relationships between taxonomic groups and geometrical morphotypes. We investigated the influence of phytoplankton shapes in the light absorption coefficient by investigating surface/volume (S/V) ratios. Phytoplankton communities from the continental shelf were detailed taxonomicaly and also categorized in geometrical morphotypes in order to calculate phytoplankton biomass, S/V ratios and size to explore relatioships with spectral light absorption coefficients. The Carbon-to-Chlorophyll ratio varied between surface and the chlorophyll maximum deph while biomass remain fairly constant, and both diatoms and dinoflagellates were the main groups present in high biomass. Exclusive morfotypes were observed for some taxonomic groups, however, S/V ratios ranges were shared by distinct taxonomic groups and morphotypes. The conversion between biovolume and biomass must take taxonomic composition into account. The mean S/V for a community show no relatioship with the magnitude of ligth absorption. The results show a low performance of pigment-based models for description of fitoplankton size classes and highlight the importance of incorporating photooaclimation for bio-optical discrimination of marine phytoplankton communities
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Ferreira, Amábile. « Propriedades ópticas das florações do fitoplâncton na quebra da plataforma argentina ». reponame:Repositório Institucional da FURG, 2013. http://repositorio.furg.br/handle/1/4168.
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Tese(mestrado) - Universidade Federal Do Rio Grande, Programa de Pós-graduação em Oceanografia Biológica, Instituto de Oceanografia, 2013.Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-11-18T12:52:36Z No. of bitstreams: 1 AMABILE.pdf: 5765676 bytes, checksum: a4926b187c0614bc4d913a29b23870ab (MD5)
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Imagens de satélite da cor do oceano detectam intensas florações do fitoplâncton durante primavera e verão ao longo da quebra de plataforma Argentina, mas são escassas as medidas ópticas in situ na região. O objetivo geral desta tese foi investigar a variabilidade das propriedades ópticas das florações do fitoplâncton na quebra de plataforma Argentina e arredores. Entre 2006 e 2009, seis cruzeiros foram conduzidos com diversas medidas biológicas e físicas, incluindo medicões bio-ópticas, dentre as quais algumas inéditas na região. As seguintes medidas foram consideradas: coeficientes spectrais de absorção da luz pelo material particulado, que inclui o fitoplâncton e detritos; coeficiente de atenuação da luz pelo material particulado a 660nm; irradiância descendente e radiância ascendente da luz com alta resolução espectral, a partir das quais se obtém os coeficientes da atenuação difusa e a reflectância do sensoriamento remoto in situ; reflectância do sensoriamento remoto medida por satélite; concentração de clorofila-a total e fracionada por classes de tamanho do fitoplâncton estimada pelo método fluorimétrico; concentrações de clorofila-a e pigmentos acessórios do fitoplâncton, obtidas por HPLC; abundância taxonômica relativa do fitoplâncton estimada por CHEMTAX; e fator de tamanho celular do fitoplâncton estimado pelos espectros de absorção da luz pelo fitoplâncton. Grande variabilidade foi observada nos coeficientes de absorção, atenuação (e espalhamento) e atenuação difusa da luz para uma dada concentração de clorofila-a e vice-versa. Grande parte dessa variabilidade pôde ser explicada por variações no tamanho celular do fitoplâncton e, portanto, ao efeito “pacote”. A variabilidade nos espectros de reflectância do sensoriamento remoto (propriedade óptica aparente) medidos in situ revelou o fitoplâncton como componente dominante nas propriedades ópticas das florações na região. Porém, a variabilidade nos coeficientes específicos (i.e., normalizados por clorofila-a) de absorção e espalhamento (propriedades ópticas inerentes), devido a variações no tamanho celular do fitoplâncton, influenciou o desempenho de modelos bio-ópticos para estimar concentração de clorofila-a por satélite. As principais situações de composição taxonômica do fitoplâncton que ocorrem durante as florações na região (dominância por diatomáceas, haptofíceas, e com contribuições destes grupos e de outros, sem dominância) foram refletidas de forma coerente nos comportamentos espectrais de absorção da luz pelo fitoplâncton, indicando o potencial em discriminar as assembleias das florações na região através de dados ópticos. Particularmente, a identificação de dominância de diatomáceas e haptofíceas, a partir de um comprimento de onda, e também pelo fator de tamanho celular do fitoplâncton, que pode ser estimado por satélite, indica o potencial em identificar a dominância de tais grupos taxonômicos por sensoriamento remoto na região.
Satellite images usually detect intense phytoplankton blooms during spring and summer along the Argentina shelf break. Because in situ optical measurements are scarce in the region, six cruises were conducted from 2006 to 2009 to measure several physical, biological, and optical properties. Some of the bio-optical properties were gathered for the first time in the region. The aim of this thesis was to characterize the optical properties of phytoplankton blooms along the Argentina shelf break e adjacent areas. For this purpose, the following measurements and data were considered: light absorption coefficients of particulate material that includes phytoplankton and detritus; light attenuation coefficient of particulate material at 660 nm; hyperspectral downwelling irradiance and upwelling radiance, from which one obtains the vertical attenuation coefficients for downwards irradiance and upwards radiance and in situ reflectance of remote sensing; total and size-fractionated chlorophyll-concentration, estimated by fluorimetric method; concentrations of chlorophyll-a and accessory pigments of phytoplankton obtained by HPLC; relative taxonomic abundance of phytoplankton estimated by CHEMTAX; a cell size parameter for phytoplankton estimated from the phytoplankton absorption spectra. Large variability was observed for absorption coefficients of phytoplankton, scattering of particles and the vertical attenuation coefficients for downwards irradiance for a given chlorophyll-a concentration. Such variability could be largely explained by variations in cell size of phytoplankton and therefore the "package" effect, as indicated by the cell size parameter. The characterization of the variability in the remote sensing reflectance (apparent optical property) measured in situ revealed phytoplankton as the dominant component on the optical properties of algal blooms in the region. Nevertheless, the variability in absorption and scattering coefficients (inherent optical properties) due to variations in cell size of phytoplankton was shown to impact the performance of bio-optical models that relies on band reflectance ratios of remote sensing to retrieve chlorophyll-a from satellite. The main taxonomic composition of the phytoplankton blooms (dominance of diatoms, haptophytes, and mixed contributions of these and others groups, but with no dominance) was consistently reflected on the spectral shape of light absorption of phytoplankton. Our results indicate a potential to discriminate phytoplankton assemblages in the region through optical data. Particularly, the identification of diatoms or haptophytes using one wavelength or through a phytoplankton cell size parameter, which can be estimated from satellite, has a potential of identifying the dominance of such taxonomic groups from remote sensing in the region.
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Bricaud-Wehrlin, Annick. « Propriétés optiques du phytoplancton : étude théorique et expérimentale : application à l'interprétation de la couleur de la mer ». Paris 6, 1989. http://www.theses.fr/1989PA066074.
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Une étude théorique des propriétés optiques des particules selon leurs caractéristiques physiques a permis de proposer une modélisation de l'absorption (effet de discrétisation), ainsi que de l'atténuation et de la diffusion de la lumière par le phytoplancton. De plus la variabilité de la relation concentration en pigments-production primaire a été examinée à partir des données in situ de diverses zones.
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王, 勝強, et Shengqiang WANG. « Remote Estimation of Phytoplankton Size Structure Using Light Absorption Spectra ». Thesis, 2014. http://hdl.handle.net/2237/20720.
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ORGANELLI, EMANUELE. « Spectral differentiation of phytoplankton light absorption related to taxonomic composition ». Doctoral thesis, 2011. http://hdl.handle.net/2158/488456.
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SPECTRAL DIFFERENTIATION OF PHYTOPLANKTON LIGHT ABSORPTION
RELATED TO TAXONOMIC COMPOSITION
Dottorando: Emanuele Organelli
Coordinatore: Prof. Paolo Grossoni Tutor: Dr.ssa Caterina Nuccio Cotutor: Dr. Luca Massi
INDICE DEGLI ARGOMENTI TRATTATI NELLA TESI
1. Differenziazione spettrale dell’assorbimento della luce in colture algali;
2. Effetti dell’irradianza sulla composizione pigmentaria e sulla forma spettrale dell’assorbimento della luce in colture algali;
3. Effetti della variabilità di un popolamento a composizione mista sull’assorbimento spettrale;
4. Caratteristiche bio-ottiche e composizione tassonomica su base pigmentaria dei popolamenti fitoplanctonici del Mar Mediterraneo;
5. Determinazione ottica della composizione dei popolamenti fitoplanctonici del Mar Mediterraneo.
PRODUZIONE SCIENTIFICA DEL TRIENNIO 2008-2010
•Organelli E., Massi L., Nuccio C., Fani F., Lazzara L., 2008. Phytoplankton spectral absorption and scattering for optical groups discrimination using complete and reduced spectral information. Atti “Ocean Optics” XIX Conference (CD-ROM), Il Ciocco, Barga (Lu) 6-10 Ottobre 2008: pp. 11.
•Organelli E., Lazzara L., Nuccio C., Massi L. 2010. Proposal of an absorption method to discriminate phytoplankton optical groups in natural mixed assemblages of the Mediterranean Sea. In Barale V., Gower, L. Alberotanza (eds): Proceedings “Ocean from Space” Venice 2010. European Commission, EUR 24324 EN: 185-186.
Rapporti tecnici
MedCO08 - Cruise Report, (2008). Ribotti A., Borghini M. (eds.). IAMC-CNR Oristano, ISMARCNR
La Spezia: pp. 27. Disponibile su: http://www.imc-it.org/progetti/CR/MedCO08_Rapp.pdf
Congressi
Organelli E., Nuccio C., Massi L., 2008. Differenziazione spettrale dell’assorbimento del fitoplancton in coltura ed in natura. Congresso dei dottorandi in scienze dei sistemi acquatici, San
Michele all’Adige (Tn) 14-16 Aprile 2008: 27. Disponibile su
http://www.aiol.info/images/file/BOOKABSdottorandi08.pdf
Organelli E., Massi L., Nuccio C., Fani F., Lazzara L., 2008. Phytoplankton spectral absorption and scattering for optical groups discrimination using complete and reduced spectral information. Ocean Optics XIX Conference, Barga (Lu) 6-10 Ottobre 2008.
Organelli E., Nuccio C., Melillo C., Mannucci M., Massi L., 2009. Phytoplankton absorption
characteristics of some offshore areas of the Mediterranean Sea. XIX Congresso AIOL, Venezia
22-25 Settembre 2009: 120. Disponibile su
http://www.aiol.info/images/stories/19cong/absract_19aiol.pdf
Organelli E., Lazzara L. Nuccio C., Massi L., 2010. Proposal of an absorption method to discriminate phytoplankton optical groups in natural mixed assemblages of the Mediterranean Sea. Ocean from Space Symposium, Scuola Grande di San Giovanni Evangelista,Venezia 26-30 Aprile 2010.
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Drzewianowski, Andrea F. « Temporal changes in phytoplankton variable fluorescence (Fv/Fm) and absorption as a result of daily exposure to high light / ». 2008. http://www.library.umaine.edu/theses/theses.asp?highlight=1&Cmd=abstract&ID=SMS2008-002.
Texte intégralChapitres de livres sur le sujet "Phytoplankton light absorption"
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Yentsch, Charles S., David A. Phinney et Lynda P. Shapiro. « Absorption and Fluorescent Characteristics of the Brown Tide Chrysophyte Its Role on Light Reduction in Coastal Marine Environments ». Dans Novel Phytoplankton Blooms, 77–83. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-75280-3_5.
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Kishino, Motoaki. « Interrelationships between Light and Phytoplankton in the Sea ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0008.
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Light energy penetrating the sea is diminished almost exponentially with depth with an accompanying drastic change in the energy spectrum as the result of absorption by various components in the seawater. Such a change in the light environment will affect phytoplankton life directly. Accordingly, in the study of light in the sea, much attention has been drawn toward the contribution of phytoplankton to the light field and also how much energy or which parts of the light spectrum are utilized at various depths by phytoplankton. Spectral distribution of underwater irradiance is determined by the processes of absorption and scattering from various components of the seawater. Since absorption plays a much more important role in spectral variation than scattering (Preisendorfer, 1961), the spectral absorption of each component should be studied in order to adequately interpret the variation of spectral irradiance in the sea. The materials absorbing light are phytoplankton, other particles, dissolved organic substances, and the water itself. Spectral characteristics of the light environment in the sea are determined by the variable ratios of these components. Several authors have attempted to measure directly the spectral absorption of individual components in seawater (Kirk, 1980; Okami et al., 1982; Kishino et al., 1984; Carder and Steward, 1985; Weidemann and Bannister, 1986). However, the determination of the absorption coefficient of natural phytoplankton is quite difficult, because no suitable technique is available for the direct measurement of absorption. Accordingly, there is still considerable uncertainty about light absorption by phytoplankton under natural conditions. Phytoplankton photosynthetic efficiency is important for the algae as well as the other organisms in the same ecosystem. Photosynthetic efficiency can be estimated fundamentally from quantum yield, which is obtained by measuring three parameters: photosynthetic rate, spectral downward irradiance, and the spectral absorption coefficient of phytoplankton. The optical system of a recently designed spectral irradiance meter is shown in Fig. 4-1. The meter has two independent cosine collectors that receive downward and upward spectral irradiance, respectively, by rotation of the mirror placed behind the collectors. After collimation, light reflected by the mirror is separated by a beam splitter.
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Perry, Mary Jane. « Measurements of Phytoplankton Absorption Other Than Per Unit of Chlorophyll a ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0010.
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Phytoplankton plays a critical role in determining light fields of the world’s oceans, primarily through absorption of light by photosynthetic pigments (see Chapters 1 to 5). Consequently there has been considerable interest from optical researchers in determining phytoplankton absorption. Conversely, from the biological point of view, this absorption assumes paramount importance because it is the sole source of energy for photosynthesis and thus should be central to direct estimates of primary production. There are two logical parts in determining this effect of phytoplankton and in estimating primary production. One is the estimation of abundance, and the other is estimation of specific effect or specific production rate. The earliest estimates of phytoplankton abundance were based on cell counts. From the time of Francis A. Richards’ Ph.D. dissertation, however, measurement of chlorophyll a concentration per unit of water volume, because of its relative ease, has assumed a central role in abundance estimation. Physiological studies and technological advances in optical instrumentation over the last decade lead me to question whether the continued use of chlorophyll a concentration to estimate phytoplankton abundance was wise either from the viewpoint of narrowing confidence intervals on estimates of absorption and production or from the viewpoint of mechanistic understanding of the processes involved. The measurement of chlorophyll a has become such a routine tool of biological oceanography, however, that the reasons for my heresy require elaboration. Some of the reasons are not too subtle. Chlorophyll a exists with other photosynthetic pigments in organized arrays associated with photosynthetic membranes. The function of these arrays is to harvest photons and transfer their energy to the specialized reaction center complexes that mediate photochemistry (see Chapter 9). The size of the arrays or packages and the ratio of chlorophyll a molecules to other light-harvesting pigments within the packages vary with phytoplankton cell size, total irradiance and its spectral distribution, as well as with other environmental parameters. It is well known that dark-adapted (= light-limited) cells increase their complements of photopigments. This plasticity in pigment packaging is evidenced in the variability of chlorophyll a-specific absorption coefficients. Simple optical models based only on chlorophyll a concentrations cannot be accurate or precise unless the effects of pigment packaging are considered.
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Kiefer, Dale A. « Light Absorption, Fluorescence, and Photosynthesis : Skeletonema Costatum and Field Measurements ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0013.
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In this chapter we will consider the fate of photons that are absorbed by phytoplankton. While such interaction will involve both the scattering and absorption of photons, we will be concerned with absorption and the subsequent processes of photosynthesis and the fluorescence of chlorophyll a. In particular and as the title of this chapter indicates, I wish to consider the environmental factors that cause variations in the cellular rates of light absorption, fluorescence, and photosynthesis. This consideration will focus on how environmental factors such as temperature, nutrient concentration, light intensity, and photoperiod effect changes in these three processes. Our approach to examining the relationship between light absorption, fluorescence, and photosynthesis is based upon phenomenological formulations between these three processes.
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« LIGHT ABSORPTION BY PHYTOPLANKTON AND THE VERTICAL LIGHT ATTENUATION : ECOLOGICAL AND PHYSIOLOGICAL SIGNIFICANCE ». Dans Oceanography And Marine Biology, 70–93. CRC Press, 1997. http://dx.doi.org/10.1201/b12590-3.
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Gordon, Howard R. « Modeling and Simulating Radiative Transfer in the Ocean ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0005.
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The propagation of light in the sea is of interest in many areas of oceanography: light provides the energy that powers primary productivity in the ocean; light diffusely reflected by the ocean provides the signal for the remote sensing of subsurface constituent concentrations (particularly phytoplankton pigments); light absorbed by the water heats the surface layer of the ocean; light absorbed by chemical species (particularly dissolved organics) provides energy for their dissociation; and the attenuation of light with depth in the water provides an estimate of the planktonic activity. Engineering applications include the design of underwater viewing systems. The propagation of light in the ocean-atmosphere system is governed by the integral-differential equation of radiative transfer, which contains absorption and scattering parameters that are characteristic of the particular water body under study. Unfortunately, it is yet to be shown that these parameters are measured with sufficient accuracy to enable an investigator to derive the in-water light field with the radiative transfer equation (RTE). Furthermore, the RTE has, thus far, defied analytical solution, forcing one to resort to numerical methods. These numerical solutions are referred to here as “simulations.” In this chapter, simulations of radiative transfer in the ocean-atmosphere system are used (1) to test the applicability of approximate solutions of the RTE, (2) to look for additional simplifications that are not evident in approximate models, and (3) to obtain approximate inverse solutions to the transfer equation, e.g., to derive the ocean’s scattering and absorption properties from observations of the light field. The chapter is based on a lecture presented at the Friday Harbor Laboratories of the University of Washington directed to both students and experts. For the students, I have tried to make the material as self-contained as possible by including the basics, i.e., by providing the basic definitions of the optical properties and radiometry for absorbing-scattering media, developing the approximate solutions to the RTE for testing the simulations, detailing the model used for scattering and absorbing properties of ocean constituents in the simulations, and briefly explaining the simulation method employed. For the experts, I hope I have provided some ideas worthy of experimental exploration.
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Morél, Andre. « Optics from the Single Cell to the Mesoscale ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0009.
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The inherent optical properties of a water body (mesoscale), namely, the absorption coefficient, the scattering coefficient, and the volume scattering function combine with the radiant distribution above the sea to yield the apparent optical properties (Preisendorfer, 1961). The radiative transfer equation is the link between these two classes of optical properties. Locally, the inherent properties of seawater are governed by, and strictly result from, the sum of the contributions of the various components, namely, the water itself, the various particles in suspension able to scatter and absorb the radiant energy, and finally the dissolved absorbing compounds. Analyzing these contributions is an important goal of optical oceanography. Among these particles, the phytoplanktonic cells, with their photosynthetic pigments, are of prime importance, in particular in oceanic waters far from terrestrial influence. They also are at the origin of other kinds of particles, such as their own debris, as well as other living “particles” grazing on them (bacteria, flagellates and other heterotrophs). Studying optics at the level of single cells and particles is therefore a requirement for a better understanding of bulk optical properties of oceanic waters. Independently of this goal, the study of the individual cell optics per se is fundamental when analyzing the pathways of radiant energy, in particular the light harvesting capabilities and the photosynthetic performances of various algae or their fluorescence responses. The following presentation is a guidline for readers who will find detailed studies in the classic books Light Scattering by Small Particles by van de Hulst (1957) and Light and Photosynthesis in Aquatic Ecosystems by Kirk (1983), as well as in a paper dealing specifically with the optics of phytoplankton by Morel and Bricaud (1986). This chapter is organized according to the title, with first a summary of the relevant theories to be applied when studying the interaction of an electromagnetic field with a particle, and then, as a transition between this scale and that of in vitro experiments, some results concerning the optical behavior of pure algal suspensions; finally the more complicated situations encountered in natural environments are briefly described to introduce the “nonlinear biological” effect (Smith and Baker, 1978a) upon the optical coefficients for oceanic waters, and to examine some of the empirical relationships, as presently available, between the pigment concentration and the optical properties of the upper ocean at mesoscale and global scale.
Actes de conférences sur le sujet "Phytoplankton light absorption"
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Gordon, Howard R., et Weiyan Gong. « Computations of solar-induced in vivo fluorescence of phytoplankton in the ocean ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thff2.
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A quasisingle scattering (QSS) model is developed for the radiative transfer of light generated at 683 nm through the solar-induced fluorescence of chlorophyll a contained in marine phytoplankton. The model utilizes the product of the spectral scalar irradiance (as a function of depth) at the exciting wavelength and the phytoplankton spectral absorption coefficient for the fluorescence source function. The radiative transfer equation is then solved using the QSS approximation. The results of the computational model are compared to, and validated by, a dual wavelength (excitation–emission) Monte Carlo simulation of the entire process including all orders of multiple scattering at both wavelengths. The QSS solution for the fluoresced irradiance, which utilizes the Monte Carlo results for the exciting wavelength, agrees with the results of the full Monte Carlo simulation to within ~2%. In contrast, while the simpler solution used by Gordon1 works well very near the surface, it fails to predict the correct fluorescence as a function of depth. The QSS model is combined with a biooptical model of the spectral inherent optical properties of phytoplankton to study the influence of the chlorophyll concentration and its vertical profile on the apparent optical properties of the ocean within the fluorescence band. The practice of modeling the fluorescence with the aid of a spectrally averaged plankton absorption is examined and shown to be valid only near the surface.
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Ackleson, Steven G. « Light scatter from Emiliania huxleyi in relation to nutrient availability ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tui5.
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Data collected in controlled laboratory experiments indicate that nutrient concentration can induce changes in the singlecell light scatter properties, as measured using flow cytometry, and beam attenuation of the marine phytoplankton Emiliania huxleyi. Nutrient-induced optical variability is due primarily to the production of external scales called coccoliths, which are composed almost entirely of calcium carbonate. Coccolith production appears to be inversely related to the concentration of nitrate. Cultures maintained in low nitrate conditions are heavily plated and ten to twenty times as many individual coccoliths are found suspended within the media. The result is an increased single-cell light scatter in both the forward and side directions. Cells grown in high nutrient conditions are either lightly plated or completely nude and fewer detached coccoliths are found within the media. As a result, single-cell light scatter is decreased. In either case, beam attenuation at 670 nm appears to be dominated by light scatter from coccoliths rather than absorption by chlorophyll.
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Moiseeva, Nataliia, Tanya Churilova, Tatiana Efimova et Olga Krivenko. « Dependence of fluorescence intensity on chlorophyll a concentration and light absorption coefficients by phytoplankton in the Black Sea (October 2017) ». Dans XXIV International Symposium, Atmospheric and Ocean Optics, Atmospheric Physics, sous la direction de Oleg A. Romanovskii et Gennadii G. Matvienko. SPIE, 2018. http://dx.doi.org/10.1117/12.2505415.
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Suslin, Vycheslav, Olga Krivenko, Tanya Churilova, Tatiana Efimova, Nataliia Moiseeva et Elena Georgieva. « Light absorption by phytoplankton, non-algal particles and colored dissolved organic matter in the Sea of Azov in January and April 2016 ». Dans XXIV International Symposium, Atmospheric and Ocean Optics, Atmospheric Physics, sous la direction de Oleg A. Romanovskii et Gennadii G. Matvienko. SPIE, 2018. http://dx.doi.org/10.1117/12.2504642.
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Moiseeva, Nataliia, Tanya Churilova, Tatiana Efimova, Alexandr Latushkin et Olga Krivenko. « Light absorption coefficients by phytoplankton pigments, suspended particles, and colored dissolved organic matter in the Crimea coastal water (the Black sea) in June 2016 ». Dans XXIII International Symposium, Atmospheric and Ocean Optics, Atmospheric Physics, sous la direction de Oleg A. Romanovskii et Gennadii G. Matvienko. SPIE, 2017. http://dx.doi.org/10.1117/12.2288351.
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Efimova, Tatiana, Tanya Churilova, Evgenii Sakhon, Nataliia Moiseeva, Ekaterina Zemlianskaia et Olga Krivenko. « Dynamics in pigment concentration and light absorption by phytoplankton, non-algal particles and colored dissolved organic matter in the Black Sea coastal waters (near Sevastopol) ». Dans XXIV International Symposium, Atmospheric and Ocean Optics, Atmospheric Physics, sous la direction de Oleg A. Romanovskii et Gennadii G. Matvienko. SPIE, 2018. http://dx.doi.org/10.1117/12.2504657.
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