Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>

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dc.contributor.authorMatthews, M W
dc.contributor.authorBernard, S
dc.date.accessioned2021-10-08T06:20:15Z
dc.date.available2021-10-08T06:20:15Z
dc.date.issued2013
dc.description.abstractA two-layered sphere model is used to investigate the impact of gas vacuoles on the inherent optical properties (IOPs) of the cyanophyte Microcystis aeruginosa. Enclosing a vacuole-like particle within a chromatoplasm shell layer significantly altered spectral scattering and increased backscattering. The two-layered sphere model reproduced features in the spectral attenuation and volume scattering function (VSF) that have previously been attributed to gas vacuoles. This suggests the model is good at least as a first approximation for investigating how gas vacuoles alter the IOPs. Measured R(subrs) was used to provide a range of values for the central value of the real refractive index, 1 + e, for the shell layer using measured IOPs and a radiative transfer model. Sufficient optical closure was obtained for 1 + e between 1.1 and 1.14, which had corresponding Chl a-specific phytoplankton backscattering, b(subbf)*, between 3.9 and 7.2 × 10-3 m2 mg-1 at 510 nm. The b(subbf)* values are in close agreement with the literature and in situ particulate backscattering measurements. R(subrs) simulated for a population of vacuolate cells was greatly enlarged relative to a homogeneous population. A sensitivity analysis of empirical algorithms for estimating Chl a in eutrophic/hypertrophic waters suggests these are robust under variable constituent concentrations and likely to be species-sensitive. The study confirms that gas vacuoles cause significant increase in backscattering and are responsible for the high Rrs values observed in buoyant cyanobacterial blooms. Gas vacuoles are therefore one of the most important bio-optical substructures influencing the IOPs in phytoplankton.
dc.identifier.apacitationMatthews, M. W., & Bernard, S. (2013). Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>. <i>Biogeosciences</i>, 10(6), 10531 - 10579. http://hdl.handle.net/11427/34234en_ZA
dc.identifier.chicagocitationMatthews, M W, and S Bernard "Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>." <i>Biogeosciences</i> 10, 6. (2013): 10531 - 10579. http://hdl.handle.net/11427/34234en_ZA
dc.identifier.citationMatthews, M.W. & Bernard, S. 2013. Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>. <i>Biogeosciences.</i> 10(6):10531 - 10579. http://hdl.handle.net/11427/34234en_ZA
dc.identifier.issn1726-4170
dc.identifier.issn1726-4189
dc.identifier.ris TY - Journal Article AU - Matthews, M W AU - Bernard, S AB - A two-layered sphere model is used to investigate the impact of gas vacuoles on the inherent optical properties (IOPs) of the cyanophyte Microcystis aeruginosa. Enclosing a vacuole-like particle within a chromatoplasm shell layer significantly altered spectral scattering and increased backscattering. The two-layered sphere model reproduced features in the spectral attenuation and volume scattering function (VSF) that have previously been attributed to gas vacuoles. This suggests the model is good at least as a first approximation for investigating how gas vacuoles alter the IOPs. Measured R(subrs) was used to provide a range of values for the central value of the real refractive index, 1 + e, for the shell layer using measured IOPs and a radiative transfer model. Sufficient optical closure was obtained for 1 + e between 1.1 and 1.14, which had corresponding Chl a-specific phytoplankton backscattering, b(subbf)*, between 3.9 and 7.2 × 10-3 m2 mg-1 at 510 nm. The b(subbf)* values are in close agreement with the literature and in situ particulate backscattering measurements. R(subrs) simulated for a population of vacuolate cells was greatly enlarged relative to a homogeneous population. A sensitivity analysis of empirical algorithms for estimating Chl a in eutrophic/hypertrophic waters suggests these are robust under variable constituent concentrations and likely to be species-sensitive. The study confirms that gas vacuoles cause significant increase in backscattering and are responsible for the high Rrs values observed in buoyant cyanobacterial blooms. Gas vacuoles are therefore one of the most important bio-optical substructures influencing the IOPs in phytoplankton. DA - 2013 DB - OpenUCT DP - University of Cape Town IS - 6 J1 - Biogeosciences LK - https://open.uct.ac.za PY - 2013 SM - 1726-4170 SM - 1726-4189 T1 - Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i> TI - Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i> UR - http://hdl.handle.net/11427/34234 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34234
dc.identifier.vancouvercitationMatthews MW, Bernard S. Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>. Biogeosciences. 2013;10(6):10531 - 10579. http://hdl.handle.net/11427/34234.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Oceanography
dc.publisher.facultyFaculty of Science
dc.sourceBiogeosciences
dc.source.journalissue6
dc.source.journalvolume10
dc.source.pagination10531 - 10579
dc.source.urihttps://dx.doi.org/10.5194/bg-10-8139-2013
dc.subject.otherMicrocystis aeruginosa
dc.subject.otherPhytoplankton
dc.subject.otherOptical properties
dc.subject.otherIOPs
dc.subject.otherCyanophyte Microcystis aeruginosa
dc.subject.otherArticle
dc.titleUsing a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>M. aeruginosa</i>
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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