Estimates of bottom roughness length and bottom shear stress in South San Francisco Bay, California

Cheng, R.S.; Ling, Chi-Hai; Gartner, Jeffrey W.; Wang, P. F.

doi:10.1029/1998jc900126

Cited by 83 publications

(93 citation statements)

References 22 publications

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“…Schlichting & Gersten 2000): (2) where κ = 0.41, z is the height above the bed, z o is the roughness length-scale, and d is the roughness height, which is a vertical offset to account for e 2 n 2 0.5 Since the flow in the benthic boundary layer is assumed to be turbulent and fully rough, Eq. (2) can be used to appropriately describe the velocity profile (Cheng et al 1999). Estimates of u * and z o were obtained by a linear regression of the velocity magnitude (U ) to ln(z) using 10 min averaged velocity profiles.…”

Section: Discussionmentioning

confidence: 99%

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Benthic flow environments affect recruitment of Crassostrea virginica larvae to an intertidal oyster reef

Whitman¹,

Reidenbach²

2012

Mar. Ecol. Prog. Ser.

111

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Restoration efforts to enhance Crassostrea virginica oyster populations along the Virginia, USA, coastline focus on creating benthic habitat suitable for larval recruitment, survival, and growth. To determine how benthic flow processes affect larval recruitment, velocity and turbulence we collected data over multiple intertidal benthic surfaces including a mud bed, a C. virginica oyster reef, and 2 restoration sites comprised of deposited C. virginica oyster shell or the relatively larger Busycotypus canaliculatus whelk shell. Mean estimates of the drag coefficient, C D , used as a measure of hydrodynamic roughness over the C. virginica reef were found to be 2 times greater than over the restoration sites and 5 times greater than over the mud bed. Enhanced fluid shear increased both peak Reynolds stresses and vertical momentum transport above the reef, but within the interstitial areas between individual oysters, velocities and turbulence were reduced. Larval settlement plates of varying triangular-shaped benthic roughness were used to mimic the natural topographic variability found along oyster reefs. The greatest larval recruitment occurred along interstitial regions between high-roughness topography, where shear stresses, which act to dislodge larvae, were found to be up to 20 times smaller than along exposed surfaces. Greater recruitment was also found on the more hydrodynamically rough whelk shell compared to the oyster shell restoration site. Results suggests that restoration efforts should consider creating 3-dimensional benthic topography similar to established oyster reefs to provide hydrodynamic conditions and settlement surfaces that promote larval recruitment, prevent burial by sediment, and provide refuge from predation.KEY WORDS: Turbulence · Boundary layers · Larvae · Recruitment · Oyster · Crassostrea virginica Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 463: [177][178][179][180][181][182][183][184][185][186][187][188][189][190][191] 2012 cess of their larvae (Nelson et al. 2004), with the goal of forming a living oyster reef over these created habitats after continued settlement and growth of generations of oysters (Nestle rode et al. 2007).Larvae preferentially settle on existing oyster reefs because they provide hard, stable substrate that contains topographic variability, thus preventing burial by sediments (Wethey 1986, Butman 1987, Koehl & Hadfield 2010 and offering protection from predation (Nestlerode et al. 2007). For reefs to develop, oysters must survive a planktonic larval phase that lasts for several weeks (Loosanoff 1965, attach to substrate, and grow from spat to large individuals. Studies have found that the higher the vertical relief of the benthic substrate, the more successful is the recruitment and growth of oysters (Lenihan 1999, Schulte et al. 2009). In addition, oysters within reef interstices were found to grow faster and live longer than oysters found at the reef surface (Bartol et al. 1999), suggesting that...

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Section: Discussionmentioning

confidence: 99%

“…(2) can be used to appropriately describe the velocity profile (Cheng et al 1999). Estimates of u * and z o were obtained by a linear regression of the velocity magnitude (U ) to ln(z) using 10 min averaged velocity profiles.…”

Section: Discussionmentioning

confidence: 99%

Benthic flow environments affect recruitment of Crassostrea virginica larvae to an intertidal oyster reef

Whitman¹,

Reidenbach²

2012

Mar. Ecol. Prog. Ser.

111

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“…Above this, a deviation from a logarithmic profile occurred because of wind stress at the surface. At each site, it was assumed that both d and z o are properties of the bed roughness and independent of time, which is valid for the timescales of the experiment (Cheng et al 1999;Stacey et al 1999b). To ensure a well defined log region over the measurement points used in the fit, only profiles having an r 2 .…”

Section: Methodsmentioning

confidence: 99%

Boundary layer turbulence and flow structure over a fringing coral reef

et al. 2006

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Measurements of velocity and rates of turbulence were made across a fringing coral reef in the Gulf of Aqaba, Red Sea, to determine the effect that the rough topography has on boundary layer mixing and flow dynamics. Observations were made at two fore-reef sites and a nearby sandy slope. The friction velocity, u * , and drag coefficient, C D , were determined directly from turbulent Reynolds stresses measured using acoustic Doppler velocimeters. Values of C D for the coral substrates ranged from 0.009 to 0.015, three to five times greater than over the sandy bottom site. The turbulence dissipation rate, e, was determined by fitting spectra of vertical velocity to the theoretical ''5/3'' law expected for the inertial subrange of turbulence. There was a local balance between production and dissipation of turbulent kinetic energy, signifying that we could estimate u * from either the mean velocity profile, turbulence, or dissipation rate of turbulent kinetic energy. Estimates from all three measures agreed well with mean u * /U o ranging from 0.10 6 0.03 to 0.12 6 0.03, indicating that existing turbulent boundary layer flow theory can be applied to flows over the rough topography of coral reefs. The bottom topography, by enhancing both reef scale and local drag and mixing levels, allows reef biota to more effectively exchange dissolved and particulate matter with oceanic waters.

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“…Regarding the bottom roughness length z 0 , it is known to vary during spring-neap cycle (Cheng et al 1999). However, when the value of z 0 is varied in the model, the values of φ z and φ x (Fig.…”

Section: Insights From Additional Sensitivity Studies In the Electronmentioning

confidence: 99%

Quantifying the Effect of Salinity Stratification on Phytoplankton Density Patterns in Estuaries

Liu

Swart

2017

Estuaries and Coasts

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To quantify the effect of salinity stratification on phytoplankton density (denoted as P ) patterns, experiments were conducted with an idealised model that couples physical and biological processes. Results show that the idealised model is capable of capturing the main features of observed P patterns in the Columbia River estuary during the spring season: during weak stratification, P is almost vertically uniform with values decreasing towards the estuary mouth, whereas during strong stratification, high values of P extend further seawards but are confined to the upper layer. Sensitivity studies reveal that the strong vertical gradients of P can only occur if the intensity of turbulence (measured by depth-averaged values of vertical eddy viscosity and eddy diffusivity) is weak. The advection of P by subtidal currents is important in obtaining a smaller along-estuary gradient of P during weak stratification and in obtaining a smaller horizontal gradient and a larger vertical gradient of P during strong stratification. Accounting for stratification controlled vertical distribution of vertical eddy viscosity and eddy diffusivity is necessary for obtaining realistic P patterns if stratification is strong, but not if stratification is weak. A higher osmotic stress, which leads to faster loss of phytoplankton in salt water, results in a larger along-estuary gradient of P if stratification is weak and in a larger vertical gradient of P if stratification is strong.

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Estimates of bottom roughness length and bottom shear stress in South San Francisco Bay, California

Cited by 83 publications

References 22 publications

Benthic flow environments affect recruitment of Crassostrea virginica larvae to an intertidal oyster reef

Benthic flow environments affect recruitment of Crassostrea virginica larvae to an intertidal oyster reef

Boundary layer turbulence and flow structure over a fringing coral reef

Quantifying the Effect of Salinity Stratification on Phytoplankton Density Patterns in Estuaries

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