Fjord light regime: Bio‐optical variability, absorption budget, and hyperspectral light availability in <scp>S</scp>ognefjord and <scp>T</scp>rondheimsfjord, <scp>N</scp>orway

Mascarenhas, V.; Voß, Daniela; Wollschlaeger, J.

doi:10.1002/2016jc012610

Cited by 27 publications

(25 citation statements)

References 72 publications

(156 reference statements)

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“…The dissolved and particulate materials in addition to water molecules interact with light and are therefore known as optically active constituents (OACs). Phytoplankton, colored dissolved organic matter (CDOM), and suspended particulate matter (SPM) being variable in time and space are the three OACs extensively studied across fresh and marine water eco-systems (Binding et al 2008;Garaba et al 2014;Holinde and Zielinski 2016;Mascarenhas et al 2017). The OACs in the medium interact with the ambient light via processes of absorption and scattering, which gives water its characteristic color.…”

Section: Fate Of Light In Water: Optically Active Constituents and Opmentioning

confidence: 99%

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Marine Optics and Ocean Color Remote Sensing

Mascarenhas

Keck

2018

YOUMARES 8 – Oceans Across Boundaries: Learning From Each Other

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Light plays an important role in aquatic ecosystems, both marine and freshwater. Penetration of light underwater influences various biogeochemical processes and also influences activities and behavioral patterns of marine organisms. In addition, dissolved and particulate water constituents present in the water column absorb and scatter light, giving water its characteristic color. The concentration or abundance of these constituents, referred to as optically active constituents (OACs) also determine light availability underwater. Thus color being an indicator of water column content, serves as a water quality parameter. Monitoring of the ocean color variables, such as the OAC concentrations and their optical properties, therefore, allows assessment of the health of an ecosystem. Advances in optical methodologies have improved the understanding of our ecosystems through multispectral and hyperspectral in situ measurements and observations. However, the ocean environment is vast and dynamic and so limitations of spatial and temporal coverage have been overcome with satellite remote sensing that provides oceanographers with repeated synoptic coverage. Being recognized as an essential climate variable (ECV) ocean color is monitored as part of the climate change initiative (CCI) of the European Space Agency (ESA). This chapter aims to provide the reader with an overview of the science of ocean color, introducing involved common terminologies and concepts and its global coverage using satellite remote sensing.

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Section: Fate Of Light In Water: Optically Active Constituents and Opmentioning

confidence: 99%

“…3b). In estuarine and fjordal ecosystems, with different fresh and saltwater mixing zones, the euphotic depth reduces gradually with increase in turbidity from the outer (downstream) to inner region (upstream) (Mascarenhas et al 2017). It is in the euphotic zone, that the majority of primary production takes place.…”

Section: Light Penetration and Euphotic Depthmentioning

confidence: 99%

Marine Optics and Ocean Color Remote Sensing

Mascarenhas

Keck

2018

YOUMARES 8 – Oceans Across Boundaries: Learning From Each Other

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“…Phytoplankton absorption coefficients were then derived as the difference between total particulate and non-algal absorption coefficients. Detailed sample analysis is presented in [17]. The a p (λ) and a nap (λ) data are published and accessible via the Pangaea database [24].…”

Section: Particulate Absorption Measurementsmentioning

confidence: 99%

“…Detailed sample analysis is presented in [17]. The a p (λ) and a nap (λ) data are published and accessible via the Pangaea database [24].…”

Section: Particulate Absorption Measurementsmentioning

confidence: 99%

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Parameterization of Spectral Particulate and Phytoplankton Absorption Coefficients in Sognefjord and Trondheimsfjord, Two Contrasting Norwegian Fjord Ecosystems

Mascarenhas

2018

Remote Sensing

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We present here parameterizations of particulate and phytoplankton absorption coefficients as functions of pigment concentrations (Tchla) in Sognefjord and Trondheimsfjord along the northwestern coast of Norway. The total particulate and non-algal optical densities were measured via quantitative filter technique (QFT) in a spectrophotometer with integrating sphere. The spectral parameter coefficients A(λ) and E(λ) of the power law describing variations of particulate and phytoplankton absorption coefficients as a function of Tchla, were not only different from those provided for open ocean case 1 waters, but also exhibited differences in the two fjords under investigation. Considering the influence of glacial meltwater leading to increased inorganic sediment load in Sognefjord we investigate differences in two different parameterizations, developed by excluding and including inner Sognefjord stations. Tchla are modelled to test the parameterizations and validated against data from the same cruise and that from a repeated campaign. Being less influenced by non-algal particles parameterizations performed well in Trondheimsfjord and yielded high coefficients of determination (R 2) of modelled vs. measured Tchla. In Sognefjord, the modelled vs. measured Tchla resulted in better R 2 with parameter coefficients developed excluding the inner-fjord stations influenced by glacial meltwater influx.

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Sea surface phytoplankton community response to nutrient and light changes

et al. 2020

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The sea surface microlayer (SML) is the boundary layer between the ocean and the atmosphere and plays a unique role in marine biogeochemistry. Phytoplankton communities in this uppermost surface layer are exposed to extreme ultraviolet (UV) radiation and potentially high nutrient supplies. In order to understand the response of SML communities to such contrasting conditions, we conducted experiments at three different sites, the North Sea (open ocean) and two sites, outer and middle fjord, in the Sognefjord, Norway, with differing physical and chemical parameters. We manipulated light, nitrogen (N) and phosphorus (P) supply to natural communities collected from the SML and compared their response to that of the underlying water (ULW) communities at 1-m depth. Phytoplankton communities in both SML and ULW responded significantly to N addition, suggesting the upper 1-m surface phytoplankton communities were N-limited. While phytoplankton growth rates were higher with high N and high light supply, biomass yield was higher under low light conditions and with a combined N and P supply. Furthermore, biomass yield was generally higher in the ULW communities compared to SML communities. Nutrient and light effects on phytoplankton growth rates, particulate organic carbon (POC) and stoichiometry varied with geographical location. Phytoplankton growth rates in both SML and ULW at the open ocean station, the site with highest salinity, did not respond to light changes, whereas the communities in the middle fjord, characterized by high turbidity and low salinity, did experience light limitation. This work on the upper surface phytoplankton communities provides new insights into possible effects of coastal darkening and increases understanding of oceanic biogeochemical cycling.

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Fjord light regime: Bio‐optical variability, absorption budget, and hyperspectral light availability in Sognefjord and Trondheimsfjord, Norway

Cited by 27 publications

References 72 publications

Marine Optics and Ocean Color Remote Sensing

Marine Optics and Ocean Color Remote Sensing

Parameterization of Spectral Particulate and Phytoplankton Absorption Coefficients in Sognefjord and Trondheimsfjord, Two Contrasting Norwegian Fjord Ecosystems

Sea surface phytoplankton community response to nutrient and light changes

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