Flow, flapping, and photosynthesis ofNereocystis leutkeana: a functional comparison of undulate and flat blade morphologies

Koehl, M. A. R.; Alberte, Randall S.

doi:10.1007/bf02112137

Cited by 220 publications

(270 citation statements)

References 22 publications

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“…This would increase turbidity and thus attenuate the supply of light to the canopy. This in turn would reduce the rate of photosynthesis (Koehl and Alberte 1988). Which of these effects dominates would depend on local conditions (rate of sediment supply, depth of water, etc.)…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamics of model Posidonia oceanica patches in shallow water

2005

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The hydrodynamics of simulated patches of the Mediterranean seagrass Posidonia oceanica were studied in laboratory flume experiments in which the height of the pronated canopy was always greater than half the total water depth. The effects of variations in speed (from 0.08 m s Ϫ1 to 0.24 m s Ϫ1) and patch configuration on the hydrodynamics were investigated. Significant speeds penetrated the patches to approximately half their height. Reducing speed did not change the flow patterns observed, except to weaken and blur them. Flow encountering a single patch formed a turbulent wake at the height of the top of the canopy. Within this wake, the vertical shear stress decreased monotonically downstream, but the Reynolds stress increased initially and then decayed. When a second patch was positioned within the region where Reynolds stress increased (referred to as the ''06 patch''), the wake center penetrated it, causing average turbulent velocities with horizontal components 3.3 times higher and vertical components 4.2 times higher than in the upstream patch. When this patch was positioned where the Reynolds stress decayed (referred to as the ''14 patch''), the wake center rose above it. Nevertheless, the turbulence in the 14 patch had horizontal components 12% higher and vertical components 22% higher on average than in the 06 patch because its upstream end was closer to the Reynolds stress maximum. Thus the ratio of the patch separation to the length of wake in which the Reynolds stress increased was identified as central to quantifying the turbulence within the downstream patch. The increased turbulence is likely to be important in determining sedimentary and ecological patch characteristics by increasing retention of particulates in suspension and thus reducing depositional rates of, for example, larvae, nutrients, and dead organic matter.

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Section: Discussionmentioning

confidence: 99%

Hydrodynamics of model Posidonia oceanica patches in shallow water

2005

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“…We chose to study patch reefs in Kaneohe Bay, not only because they are known habitat for P. sibogae, but also because the wave conditions they experience can be produced in our laboratory flume, whereas the longerperiod large waves hitting the exposed seaward edges of coral reefs cannot. The reef on which we did our detailed ADV measurements experienced flow typical of the patch reefs in Kaneohe Bay (Bathen 1968;Koehl and Hadfield 2004). The dominant coral species at our study site was Porites compressa (Fig.…”

Section: Methodsmentioning

confidence: 97%

“…We used the C D for a sphere sitting on a surface. Values of C D were obtained from Coleman (1977) and expressed as: Competent larvae (i.e., larvae developmentally capable of metamorphosis) were gently pipetted into a glass well (14 mm in diameter and 3 mm deep) containing a water sample collected from the spaces within a Porites compressa reef , which induced them to withdraw their ciliated swimming organ, (the velum), sink, and attach to surfaces Koehl and Hadfield 2004). Larvae were videotaped (60 frames sec 21 ) using a SPI-Minicam color video camera on a Wild stereomicroscope at a magnification of 503.…”

Section: Methodsmentioning

confidence: 99%

“…Water motion across the benthos at wave-exposed sites is characterized by slow net horizontal transport but high instantaneous velocities, accelerations, and turbulence (Koehl 1977;Koehl and Powell 1994;Koehl and Hadfield 2004). Wave action can have a dramatic effect on the small-scale flow patterns near benthic surfaces and can greatly increase intermittent bed shear stresses compared with those in unidirectional currents (Reidenbach et al 2007).…”

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confidence: 99%

“…We chose P. sibogae as the research system for our investigation because it has for many years been a model organism in studies of larval settlement and metamorphosis, and thus there is a wealth of background information available about this species. Larvae of P. sibogae are induced to sink, adhere to surfaces, and undergo metamorphosis into benthic juveniles by a dissolved chemical cue from their prey, the branching coral Porites compressa (Hadfield and Pennington 1990;Hadfield and Koehl 2004;Koehl and Hadfield 2004). Shallow coral reefs in Hawaii, which are exposed to turbulent, wave-driven flow , are dominated by P. compressa (Fig.…”

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confidence: 99%

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Hydrodynamic forces on larvae affect their settlement on coral reefs in turbulent, wave-driven flow

2009

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This study investigates a key aspect of how ambient flow affects the recruitment of water-dispersed marine larvae onto benthic substrata: the sweeping away of larvae that have landed on surfaces. Through a combination of field and laboratory measurements, we studied how waves interact with a complex substratum to affect hydrodynamic forces encountered by microscopic larvae sitting at different positions on the bottom terrain. We used larvae of the nudibranch Phestilla sibogae settling onto coral reefs as the system to address this question. Laser Doppler anemometry was utilized within a laboratory flume to measure water velocities encountered 200 mm from coral surfaces by microscopic larvae sitting at different locations within a reef of the branching coral Porites compressa. Comparing wave-driven flow, based on conditions measured over P. compressa reefs in Hawaii, with unidirectional flow of the same mean velocity, we found that peak shear stresses along coral surfaces were ,15 times greater and hydrodynamic forces on larvae were ,10 times higher in wave conditions. Peak forces on larvae sitting on the reef top were 3-10 times greater than on larvae 5-10 cm below the reef top. Intermittent bursts of high velocity, which occurred more often at the reef top than within it, determined the settlement probability for larvae in different reef microhabitats. The faster and more strongly a larva sticks to a surface, the higher the probability of successful settlement. Using values for P. sibogae adhesive strength, we predict they can settle only on sheltered surfaces within reefs.

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2005

Dynamics of Marine Ecosystems

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Flow, flapping, and photosynthesis ofNereocystis leutkeana: a functional comparison of undulate and flat blade morphologies

Cited by 220 publications

References 22 publications

Hydrodynamics of model Posidonia oceanica patches in shallow water

Hydrodynamics of model Posidonia oceanica patches in shallow water

Hydrodynamic forces on larvae affect their settlement on coral reefs in turbulent, wave-driven flow

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