Identification of coccolithophore blooms in the SE Atlantic Ocean off Namibia by satellites and in-situ methods

Siegel, Herbert; Ohde, Thomas; Gerth, Monika; Lavik, Gaute; Leipe, Thomas

doi:10.1016/j.csr.2006.10.003

Cited by 40 publications

(35 citation statements)

References 25 publications

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“…Phytoplankton production in the ocean is normally limited by nutrient availability and solar radiation (Tang et al, 2004a;Siegel et al, 2007;Dwivedi et al, 2008). The study area is located in a relatively oligotrophic tropical-subtropical ocean (Tang et al, 1999(Tang et al, , 2004b.…”

Section: The Region Of the Phytoplankton Bloomsmentioning

confidence: 99%

Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

Wang

Tang

Sui

2010

Journal of Marine Systems

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Section: The Region Of the Phytoplankton Bloomsmentioning

confidence: 99%

Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

Wang

Tang

Sui

2010

Journal of Marine Systems

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“…The independence of bottom topography and discolorations at the Namibian coast is demonstrated in Figures 4A and 4B. The bottom structures are different from the patterns of discolorations because only a low reflective diatomaceous mud belt is found at the Namibian shelf [2] and the transparency of the high biological productive water is low [5]. Furthermore, the discolorations developed in a completely different manner than the patterns of oceanbottom topography.…”

Section: Resultsmentioning

confidence: 94%

“…This suspended material could be responsible for a part of the observed discolorations in the area around this river. There are many algae blooms in the area of investigation because of the upwelling of nutrient-rich water masses [5][6][7]. The algae blooms (diatom, coccolithophorid, red tides and others) discolour the water depending on the algae species and could also generate the turquoise discolorations.…”

Section: Resultsmentioning

confidence: 99%

“…The newest investigations have demonstrated that most of the nearshore discolorations are caused by oxidised hydrogen sulphide which is produced in the shelf region in the sediment layer or in the water layer near the seafloor by sulphate reduction of anaerobic bacteria [2,4]. Different absorbing and scattering phytoplankton blooms were often observed in the coastal area off Namibia due to the transport of nutrients by upwelling processes [5][6][7]. Sometimes these blooms discoloured the water surface bluish-green to turquoise depending on their optical properties.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the blooms were similarly turquoise like the hydrogen sulphide events. Newer studies have demonstrated that the offshore plumes outside the immediate upwelling area are generated by coccolithophores increasing the backscattering due to the calcite coccoliths [5].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

Ohde

2009

Open Geosciences

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Hydrogen sulphide eruptions with their typical turquoise discolorations at the water surface are a unique phenomenon along the Namibian coastline. The remote sensing techniques of ocean colour sensors and microwave scatterometers were used for the investigation of such events. The studies with ocean colour sensors showed that the turquoise discolorations near the Namibian coast were neither linked to dust deposition into the water column by desert storms nor to the reflection of bright material in shallow water areas. In addition, other coloured marine events like algae blooms and river outflows were differentiable from the hydrogen sulphide eruptions by their special optical properties. Quasi-true colour images and spectral identification methods were utilised to monitor and investigate the spatial and temporal distribution of sulphide events. In the past years, they were sometimes and locally limited discovered. Newest remote sensing observations including our own investigations have established that the occurrence of sulphide events is more frequent and longer lasting. The north-westerly direction of propagation and their velocity between 12 cm s −1 and 15 cm s −1 were derived from an event on 14 April 2004. Lastly, the microwave scatterometer remote sensing was applied to investigate the relation of sulphide events to oceanographic conditions. The events from May 2004 were clearly related to strong coastal upwelling.

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Bio-optical variability at a Vancouver Island aquaculture site

et al. 2016

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Variability of the particulate beam attenuation, scattering, and backscattering coefficients, along with discrete measurements of HPLC derived pigments and particulate organic carbon, is investigated within and beside a finfish aquaculture cage on the west coast of Vancouver Island, Canada. Large bio‐optical variability was observed over three seasons: fall, spring, and summer. The use of multiple optical proxies for organic particle concentrations, bulk particle‐size distributions, and compositions allowed for the characterization of the particle assemblage over the dynamic conditions. Specifically, in fall, low biological productivity and surface influences from runoff were observed. In the lower‐cage, after feeding the fish, optical proxies suggest the dominance of large particles with high indices of refraction, possibly due to the influence of fish fecal particles. Optical variability in spring was driven by diatom bloom conditions (Chaetoceros and Skeletonema). Strong bio‐optical relationships were observed and the optical proxies suggest a particle‐size distribution (PSD) dominated by large particles with low indices of refraction. In turn, summer conditions displayed noticeably high and persistent particulate backscattering in the surface waters, suggesting the presence of an Emiliania huxleyi bloom. Neither spring nor summer showed distinct influences by aquaculture wastes indicating that optical characterization of particulate waste dispersal is likely constrained to low ambient seston conditions. Outside of these conditions bio‐optical analysis would be beneficial for environmental monitoring of ambient particles moving through aquaculture systems.

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Identification of coccolithophore blooms in the SE Atlantic Ocean off Namibia by satellites and in-situ methods

Cited by 40 publications

References 25 publications

Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

Bio-optical variability at a Vancouver Island aquaculture site

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