Nepheloid Layers

McCave, I.N.

doi:10.1006/rwos.2001.0420

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…Hence, we suggest that internal waves of tidal period may act as the primary mechanism in the erosion or non-deposition of contourite terraces T1, T2 and T3 as have been proposed along the south Atlantic continental slopes (e.g., Hernández-Molina et al, 2009;Preu et al, 2013). These can mobilize and re-suspend bottom sediments (e.g., Cacchione et al, 2002;McCave, 2009;Pomar et al, 2012;Shanmugam, 2013).…”

Section: The Effect Of Internal Tidesmentioning

confidence: 58%

Contourite depositional systems along the Mozambique channel: The interplay between bottom currents and sedimentary processes

Thiéblemont

Hernández-Molina

Miramontes

et al. 2019

Deep Sea Research Part I: Oceanographic Research Papers

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We present a combined study of the geomorphology, sedimentology, and physical oceanography of the Mozambique Channel to evaluate the role of bottom currents in shaping the Mozambican continental margin and adjacent Durban basin. Analysis of 2D multichannel seismic reflection profiles and bathymetric features revealed major contourite deposits with erosive (abraded surfaces, contourite channels, moats, furrows and scours), depositional (plastered and elongated-mounded drifts, sedimentary waves), and mixed (terraces) features, which were then used to construct a morphosedimentary map of the study area. Hydrographic data and hydrodynamic modelling provide new insights into the distribution of water masses, bottom current circulation and associated processes (e.g., eddies, internal waves, etc.) occurring along the Mozambican slope, base-of-slope and basin floor. Results from this work represent a novel deep-sea sedimentation model for the Mozambican continental margin and adjacent Durban basin. This model shows 1) how bottom circulation of water masses and associated sedimentary processes shape the continental margin, 2) how interface positions of watermasses with contrasting densities (i.e., internal waves) sculpt terraces along the slope at a regional scale, and 3) how morphologic obstacles (seamounts, Mozambique Ridge, etc.) play an essential role in local water mass behaviours and dynamics. Further analysis of similar areas can expand understanding of the global role of bottom currents in deep-sea sedimentation. Highlights► Combined study of the geomorphology, sedimentology, and physical oceanography of the Mozambique Channel. ► Bottom circulation of water masses and associated sedimentary processes shape the continental margin. ► Interface positions of water-masses with contrasting densities (i.e., internal waves) sculpt terraces along the slope at a regional scale. ► Morphologic obstacles play an essential role in local water mass behaviours and dynamics.

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Section: The Effect Of Internal Tidesmentioning

confidence: 58%

Contourite depositional systems along the Mozambique channel: The interplay between bottom currents and sedimentary processes

Thiéblemont

Hernández-Molina

Miramontes

et al. 2019

Deep Sea Research Part I: Oceanographic Research Papers

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“…However, the possibility that zooplankton attracted to the fluorometer light also contributed to that pattern had not been proposed. Moored instrument packages containing fluorescence and turbidity sensors have been routinely used in estuarine and coastal regions for several decades (McCave 2010;Moore 2010;Yagi et al 2015;Gorokhovich 2016;Zamyadi et al 2016;Jafar-Sidik et al 2017;Kakehi et al 2017). Fluorescence and turbidity measurements obtained during the night in such studies should be reevaluated.…”

Section: Discussionmentioning

confidence: 99%

“…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 2013). More sophisticated instruments, such as underwater nephelometers and fluorometers, were developed in the mid-20th century (Strickland and Parsons 1972), followed by miniaturized instruments to simultaneously measure fluorescence and turbidity (McCave 2010;Yagi et al 2015;Gorokhovich 2016;Zamyadi et al 2016;Jafar-Sidik et al 2017;Kakehi et al 2017).…”

mentioning

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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“…Enhanced aging may occur due to 14 C radioactive decay of sedimentary OM entrained in repeated deposition-resuspension loops in the benthic boundary layer induced by local hydrodynamic processes. A single deposition-resuspension loop may be up to 1-2 months in duration (van der Loeff et al, 2002), and mean residence times of freshly deposited OM in surface seabed sediments prior to resuspension may be on the order of years (McCave, 2009;McKee et al, 1983). Resuspended particles can experience numerous such episodes of emplacement/displacement between OM and inorganic particles due to sediment winnowing and reworking following short-term deposition (Hedges et al, 1999;Tao et al, 2016) and associated benthic nepheloid layer transport prior to permanent sedimentation (McKee et al, 1983).…”

Section: Geophysical Research Lettersmentioning

confidence: 99%

Organic Carbon Aging During Across‐Shelf Transport

Bao

Uchida

Zhao

et al. 2018

Geophysical Research Letters

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Compound‐specific radiocarbon analysis was performed on different grain‐size fractions of surficial sediments to examine and compare lateral transport times (LTTs) of organic carbon. 14C aging of long‐chain leaf wax fatty acids along two dispersal pathways of fluvially derived material on adjacent continental margins implies LTTs over distances of ~30 to 500 km that range from hundreds to thousands of years. The magnitude of aging differs among grain size fractions. Our finding suggests that LTTs vary both temporally and spatially as a function of the specific properties of different continental shelf settings. Observations suggest that 14C aging is widespread during lateral transport over continental shelves, with hydrodynamic particle sorting inducing age variations among organic components residing in different grain sizes. Consideration of these phenomena is of importance for understanding carbon cycle processes and interpretation on sedimentary records on continental margins.

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Nepheloid Layers

Cited by 5 publications

References 15 publications

Contourite depositional systems along the Mozambique channel: The interplay between bottom currents and sedimentary processes

Contourite depositional systems along the Mozambique channel: The interplay between bottom currents and sedimentary processes

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

Organic Carbon Aging During Across‐Shelf Transport

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