The relationship between Suspended Particulate Matter and Turbidity at a mooring station in a coastal environment: consequences for satellite-derived products

Jafar-Sidik, Madihah; Gohin, Francis; Bowers, David; Howarth, John; Hull, Tom

doi:10.1016/j.oceano.2017.04.003

Cited by 44 publications

(20 citation statements)

References 42 publications

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“…However, this is likely an underestimate of the influence of bed shear stress on SPM; 8 d estimates of SPM are uncertain due to the sporadic nature of the remote sensing data because of cloud cover. In addition, there is an imperfect relationship between satellitederived SPM and in situ SPM, potentially because of a failure to distinguish between SPM and phytoplankton in some months (Jafar-Sidik et al, 2017). This implies that there will be a significantly large error term in our linear regressions due to differences between satellite and in situ SPM and that the R 2 values reported here underestimate the influence of bed shear stress on SPM.…”

Section: Discussionmentioning

confidence: 87%

“…The region of study was the northwest European Continental Shelf, which we define to be regions shallower than 150 m between 48 and 62 • N and between 13 • W and 9 • E. This region has large variation in seabed sediments (Wilson et al, 2018), wave and tidal conditions (Neill et al, 2014;Semedo et al, 2015), suspended sediment (van der Molen et al, 2016), and natural and anthropogenic disturbance of the seafloor (Aldridge et al, 2015;Diesing et al, 2013).…”

Section: Summary and Overviewmentioning

confidence: 99%

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Increasing turbidity in the North Sea during the 20th century due to changing wave climate

Wilson

Heath

2019

Ocean Sci.

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Abstract. Data on Secchi disc depth (the depth at which a standard white disc lowered into the water just becomes invisible to a surface observer) show that water clarity in the North Sea declined during the 20th century, with likely consequences for marine primary production. However, the causes of this trend remain unknown. Here we analyse the hypothesis that changes in the North Sea's wave climate were largely responsible by causing an increase in the concentrations of suspended particulate matter (SPM) in the water column through the resuspension of seabed sediments. First, we analysed the broad-scale statistical relationships between SPM and bed shear stress due to waves and tides. We used hindcasts of wave and current data to construct a space–time dataset of bed shear stress between 1997 and 2017 across the northwest European Continental Shelf and compared the results with satellite-derived SPM concentrations. Bed shear stress was found to drive most of the inter-annual variation in SPM in the hydrographically mixed waters of the central and southern North Sea. We then used a long-term wave reanalysis to construct a time series of bed shear stress from 1900 to 2010. This shows that bed shear stress increased significantly across much of the shelf during this period, with increases of over 20 % in the southeastern North Sea. An increase in bed shear stress of this magnitude would have resulted in a large reduction in water clarity. Wave-driven processes are rarely included in projections of climate change impacts on marine ecosystems, but our analysis indicates that this should be reconsidered for shelf sea regions.

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Section: Discussionmentioning

confidence: 87%

Section: Summary and Overviewmentioning

confidence: 99%

Increasing turbidity in the North Sea during the 20th century due to changing wave climate

Wilson

Heath

2019

Ocean Sci.

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“…Methodologies for their quantification have been developed for over 150 years, starting with the Secchi disk, proposed in the mid‐19th century (Watson and Zielinski ). More sophisticated instruments, such as underwater nephelometers and fluorometers, were developed in the mid‐20th century (Strickland and Parsons ), followed by miniaturized instruments to simultaneously measure fluorescence and turbidity (McCave ; Yagi et al ; Gorokhovich ; Zamyadi et al ; Jafar‐Sidik et al ; Kakehi et al ).…”

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confidence: 99%

Biased measurements by stationary turbidity‐fluorescence instruments due to phototactic zooplankton behavior

Tanaka

Genin

Lopes

et al. 2019

Limnology & Ocean Methods

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Submersible fluorescence and turbidity sensors are widely used in studies of oceans and lakes. To reduce the instrument size, an overlapping interrogation volume is commonly used for the two sensors. Fluorescence sensors emit blue light for excitation and measure the red light emitted by excited chlorophyll pigments. However, during the night, many phototactic zooplankters are attracted to the blue light. If the instrument is fixed in place (e.g., on a mooring), the aggregation of the attracted animals may bias both the fluorescence and turbidity readings. To examine this potential bias, we carried out experiments with natural assemblages of zooplankton and Artemia nauplii in tanks equipped with a commercially available fluorescence‐turbidity sensor. Our findings indicate that zooplankters were attracted by the blue light emitted from a fluorometer during the dark, biasing the reading of both sensors. The bias in fluorescence was likely due to phytoplankton in the guts of the aggregated zooplankton. The induction of turbulence in the tank greatly reduced the bias, likely due to the inability of the zooplankton to counteract the resulting flow and swim toward the light. Field observations carried out with a similar instrument in a coastal station off Japan were consistent with the laboratory experiments. Our findings indicate a need to redesign coupled fluorescence‐turbidity sensors and to reevaluate the results of past studies where they had been used with stationary observing systems.

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“…A relationship can be inferred between turbidity and Suspended Particulate Matter (SPM) [62,63] but this relation is highly dependent on the area explored and on the season considered as well [64]. Consequently, the present SVR model can be used to estimate suspended matter concentration, but only on the VKP region where this regression was set.…”

Section: Validity Of the Svr For Turbidity Or Spm Estimation And Commentioning

confidence: 99%

Application of the Support Vector Regression Method for Turbidity Assessment with MODIS on a Shallow Coral Reef Lagoon (Voh-Koné-Pouembout, New Caledonia)

Wattelez

Dupouy

Lefêvre

et al. 2017

Water

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Abstract:Particle transport by erosion from ultramafic lands in pristine tropical lagoons is a crucial problem, especially for the benthic and pelagic biodiversity associated with coral reefs. Satellite imagery is useful for assessing particle transport from land to sea. However, in the oligotrophic and shallow waters of tropical lagoons, the bottom reflection of downwelling light usually hampers the use of classical optical algorithms. In order to address this issue, a Support Vector Regression (SVR) model was developed and tested. The proposed application concerns the lagoon of New Caledonia-the second longest continuous coral reef in the world-which is frequently exposed to river plumes from ultramafic watersheds. The SVR model is based on a large training sample of in-situ turbidity values representative of the annual variability in the Voh-Koné-Pouembout lagoon (Western Coast of New Caledonia) during the 2014-2015 period and on coincident satellite reflectance values from MODerate Resolution Imaging Spectroradiometer (MODIS). It was trained with reflectance and two other explanatory parameters-bathymetry and bottom colour. This approach significantly improved the model's capacity for retrieving the in-situ turbidity range from MODIS images, as compared with algorithms dedicated to deep oligotrophic or turbid waters, which were shown to be inadequate. This SVR model is applicable to the whole shallow lagoon waters from the Western Coast of New Caledonia and it is now ready to be tested over other oligotrophic shallow lagoon waters worldwide.

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The relationship between Suspended Particulate Matter and Turbidity at a mooring station in a coastal environment: consequences for satellite-derived products

Cited by 44 publications

References 42 publications

Increasing turbidity in the North Sea during the 20th century due to changing wave climate

Increasing turbidity in the North Sea during the 20th century due to changing wave climate

Biased measurements by stationary turbidity‐fluorescence instruments due to phototactic zooplankton behavior

Application of the Support Vector Regression Method for Turbidity Assessment with MODIS on a Shallow Coral Reef Lagoon (Voh-Koné-Pouembout, New Caledonia)

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