Hydrodynamics of larval settlement: The influence of turbulent stress events at potential recruitment sites

Crimaldi, John P.; Thompson, Janet K.; Rosman, Johanna H.; Lowe, Ryan J.; Koseff, Jeffrey R.

doi:10.4319/lo.2002.47.4.1137

Cited by 115 publications

(112 citation statements)

References 44 publications

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“…They imply that particles would remain in suspension longer in patches located within the wake of other patches than in those where patch spacing is greater than wake length. This would alter rates of pollen interception by seagrass carpels (Ackerman 2002) and would reduce the rates of deposition of bivalves and other pelagic larvae (Irlandi et al 1999;Crimaldi et al 2002). This implies that these ''in-wake'' patches would have sparser populations of adult bivalves and other fauna such as gastropods and polychaetes than homogeneous meadows (Bologna and Heck 2002).…”

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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“…Instantaneous stress events caused by wave driven flows may be a better predictor of larval 7 settlement than mean stress (Crimaldi et al, 2002). Wave driven flows result in instantaneous 8 high turbulent flow that increase shear stress and reduce the thickness of the viscous sublayer 9 (Koehl, 2007).…”

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confidence: 99%

“…If larvae settle more on substrates with pits and 21 grooves, one could speculate that larval settlement rate may be greater on plates with high 1 settlement than on plates with low settlement, as roughness increases with settlement (see 2 Thomason et al, 1998 for effects of adult barnacles on flows). On the other hand, the type and 3 spacing of roughness elements could decrease the chance of contact or attachment if turbulence 4 is increased (Crimaldi et al, 2002). Larval response to fine-scale hydrodynamics in concert with 5 a positive response to conspecific or other chemical cues could be predictors of a settlement 6 increase.…”

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confidence: 99%

“…12 Variability in roughness, however, creates microhabitats with reduced shear stress. In 13 microhabitats such as rough subtidal surfaces (Walters, 1992) or within coral reefs (Reidenbach 14 et al, 2009), and clam beds (Crimaldi et al, 2002), larvae will have longer contact times and 15 have a greater opportunity to settle. Natural patchiness of roughness elements will result in 16 greater variability in instantaneous stresses and events, and this may translate to greater 17 variability in larval settlement.…”

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confidence: 99%

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Causes of decoupling between larval supply and settlement and consequences for understanding recruitment and population connectivity

Pineda

Porri

Starczak

et al. 2010

Journal of Experimental Marine Biology and Ecology

176

100

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Marine broadcast spawners have two-phase life cycles, with pelagic larvae and benthic adults. 2 Larval supply and settlement link these two phases and are crucial for the persistence of marine 3 populations. Mainly due to the complexity in sampling larval supply accurately, many 4 researchers use settlement as a proxy for larval supply. Larval supply is a constraining variable 5 for settlement because, without larval supply, there is no settlement. Larval supply and 6 settlement may not be well correlated, however, and settlement may not consistently estimate 7 larval supply. 8This paper explores the argument that larval supply (i.e., larval abundance near settlement sites) 9 may not relate linearly to settlement. We review the relationship between larval supply and 10 settlement, from estimates and biases in larval supply sampling, to non-behavioral and 11 behavioral components, including small-scale hydrodynamics, competency, gregarious behavior, 12 intensification of settlement, lunar periodicity, predation and cannibalism. Physical and structural 13 processes coupled with behavior, such as small-scale hydrodynamics and intensification of 14 settlement, sometimes result in under-or overestimation of larval supply, where it is predicted 15 from a linear relationship with settlement. Although settlement is a function of larval supply, 16 spatial and temporal processes interact with larval behavior to distort the relationship between 17 larval supply and settlement, and when these distortions act consistently in time and space, they 18 cause biased estimates of larval supply from settlement data. 19Most of the examples discussed here suggest that behavior is the main source of the decoupling 20 between larval supply and settlement because larval behavior affects the vertical distribution of 21 3 larvae, the response of larvae to hydrodynamics, intensification of settlement, gregariousness, 1 predation and cannibalism. Thus, larval behavior seems to limit broad generalizations on the 2 regulation of settlement by larval supply. Knowledge of the relationship is further hindered by 3 the lack of a well founded theoretical relationship between the two variables. 4The larval supply-settlement transition may have strong general consequences for population 5 connectivity, since larval supply is a result of larval transport, and settlement constrains 6 recruitment. Thus, measuring larval supply and settlement effectively allows more accurate 7 quantification and understanding of larval transport, recruitment and population connectivity. 8 9 4

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“…The velocity gradient is steepest and the profile is linear with respect to distance from the substratum within the viscous sublayer (Schlichting and Gersten 2000). Although many types of marine invertebrate larvae are small enough (a few hundred microns) to lie fully within the viscous sublayer after they have landed on the substratum, small-scale topographic variability combined with instabilities in the flow due to bursting and sweeping of turbulent eddies can periodically disrupt this viscous sublayer, exposing the larvae to higher instantaneous flow forces (Ligrani 1986;Wright 1989;Crimaldi et al 2002).…”

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confidence: 99%

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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Hydrodynamics of larval settlement: The influence of turbulent stress events at potential recruitment sites

Cited by 115 publications

References 44 publications

Hydrodynamics of model Posidonia oceanica patches in shallow water

Hydrodynamics of model Posidonia oceanica patches in shallow water

Causes of decoupling between larval supply and settlement and consequences for understanding recruitment and population connectivity

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

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