Limnology and Oceanography: Fluids and Environments最新文献_第3页

Swimming by medusae Sarsia tubulosa in the viscous vortex ring limit 水母在粘性涡环极限中游泳

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-08-19 DOI: 10.1215/21573689-2338313

Kakani Katija, Houshuo Jiang

{"title":"Swimming by medusae Sarsia tubulosa in the viscous vortex ring limit","authors":"Kakani Katija, Houshuo Jiang","doi":"10.1215/21573689-2338313","DOIUrl":"10.1215/21573689-2338313","url":null,"abstract":"<div>\u0000 As organisms swim in their natural environment, they are constantly striving to forage successfully, escape from predation, and search for mates to reproduce. At some stage in their life cycle, most organisms have operated in environments where the Reynolds number (Re) is small and have developed strategies and behaviors to overcome the effects of viscosity. Relatively little is known about these animal-fluid interactions at relatively small (1 < Re < 10), viscous size scales. Swimming organisms have been described analytically using the self-propelled swimmer model, which applies for conditions where the organism is assumed to swim steadily in a noninertial fluid regime or Re < 1. However, for unsteady swimming processes, such as jumping or jet propulsion, these steady models do not account for the impulsiveness of the swimming behavior. The unsteady impulsive Stokeslet and impulsive stresslet models have been used to describe jumping by copepods, but neither model has been applied to jetting organisms. The purpose of this study is to identify which analytical, unsteady model best describes swimming by jetting organisms at small, viscous length scales. We conducted high-speed kinematic and velocity field measurements on 1-mm velar-diameter Sarsia tubulosa, a jetting, ambush-feeding medusa. From our measurements and comparisons using similar criteria established for copepod jumping, we conclude that the impulsive Stokeslet model more accurately describes swimming by small S. tubulosa. Since the hydrodynamic signature of an impulsive Stokeslet does not have strong vorticity bounding the medusa's body, this finding has important ecological implications for the ambush-feeding predator.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"103-118"},"PeriodicalIF":0.0,"publicationDate":"2013-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2338313","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Fluid motion mediates biochemical composition and physiological aspects in the green alga Dunaliella primolecta Butcher 流体运动介导绿藻杜氏藻的生化组成和生理方面

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-08-02 DOI: 10.1215/21573689-2326826

Anwar Chengala, Miki Hondzo, Douglas G. Mashek

{"title":"Fluid motion mediates biochemical composition and physiological aspects in the green alga Dunaliella primolecta Butcher","authors":"Anwar Chengala, Miki Hondzo, Douglas G. Mashek","doi":"10.1215/21573689-2326826","DOIUrl":"10.1215/21573689-2326826","url":null,"abstract":"<div>\u0000 Experiments were conducted in a laboratory bioreactor to study the effect of small-scale fluid motion on the composition of some key biochemical compounds and physiological processes of the microalga, Dunaliella primolecta Butcher. The bioreactor with submersible speakers generated nearly homogeneous and isotropic turbulence. Fluid flow was the only systematically controlled experimental variable, with other environmental conditions, including light intensity, temperature, initial salinity, and nutrient concentration, nearly similar during the experimental measurements. The growth, protein, and fatty acid accumulation of D. primolecta were enhanced by the moving fluid flow in the bioreactor. Over an 8-d experiment under turbulent fluid flow conditions, a twofold increase in cell number, chlorophyll, protein, and total fatty acid concentrations was observed in D. primolecta. Conversely, no significant increase in these variables was observed under stagnant fluid conditions. The results could have important implications for the design and operation of natural and engineered bioreactors under specified fluid flow conditions for efficient bioenergy production from microalgae.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"74-88"},"PeriodicalIF":0.0,"publicationDate":"2013-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2326826","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

The maintenance of the subsurface chlorophyll maximum in the stratified western Irish Sea 层状西爱尔兰海地下叶绿素最大值的维持

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-06-20 DOI: 10.1215/21573689-2285100

Charlotte Williams, Jonathan Sharples, Mattias Green, Claire Mahaffey, Tom Rippeth

{"title":"The maintenance of the subsurface chlorophyll maximum in the stratified western Irish Sea","authors":"Charlotte Williams, Jonathan Sharples, Mattias Green, Claire Mahaffey, Tom Rippeth","doi":"10.1215/21573689-2285100","DOIUrl":"10.1215/21573689-2285100","url":null,"abstract":"<div>\u0000 The diapycnal flux of nitrate from the deep water provides a limit on new production in the subsurface chlorophyll maximum (SCM) during summer in stratified shelf seas. Here we estimate the diapycnal nitrate flux into the SCM in the stratified western Irish Sea (SWIS). Sampling took place immediately before neap tides when winds were light, so flux estimates reported provide a lower limit to nitrate supply to the SCM. Measurements of turbulent kinetic energy dissipation, chlorophyll a, and nitrate were used to estimate the flux of nitrate and chlorophyll through the SCM. Turbulent dissipation was low in the SCM (10–9 to 10–7 m2 s–3), driving a correspondingly low nitrate flux into the SCM (0.31 mmol m–2 d–1). The thermocline was marginally stable throughout sampling, and thus the addition of shear would likely result in shear instabilities and mixing. We show that although the SWIS is documented as having an energetic internal tide at this time, there was a low level of dissipation within the thermocline. We argue that the internal tide sets up background shear, which results in marginal stability. The addition of extra shear through the passage of nonlinear internal waves and/or the wind can trigger instability and mixing. We extrapolate our flux estimate over the summer and show that the nitrate flux is insufficient to sustain the documented summer production estimates for the SWIS. This suggests that episodic events are likely to be important for nitrate fluxes, or even largely responsible for the nitrate flux that sustains the SCM.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"61-73"},"PeriodicalIF":0.0,"publicationDate":"2013-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2285100","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26

Lagrangian transport pathways in the northeast Atlantic and their environmental impact 东北大西洋拉格朗日运输路径及其环境影响

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-05-24 DOI: 10.1215/21573689-2152611

Iria Sala, Rui M. A. Caldeira, Sheila N. Estrada-Allis, Elsa Froufe, Xavier Couvelard

{"title":"Lagrangian transport pathways in the northeast Atlantic and their environmental impact","authors":"Iria Sala, Rui M. A. Caldeira, Sheila N. Estrada-Allis, Elsa Froufe, Xavier Couvelard","doi":"10.1215/21573689-2152611","DOIUrl":"10.1215/21573689-2152611","url":null,"abstract":"<div>\u0000 This study focused on mapping the general transport pathways of the northeast Atlantic Ocean by using the Regional Oceanic Modeling System to calculate ocean current velocity components (u, v, w), and Ariane (an off-line Fortran code dedicated to the computation of three-dimensional streamlines from velocity fields) to calculate the transport of particles around the numerical model domain. The study was undertaken using a 10-year climatic simulation. Statistical comparisons with satellite and in situ data showed that the ocean circulation model captured known regional oceanographic features. Four depth ranges showed different Lagrangian transport pathways, 0–10 m, 20–200 m, 300–500 m, and 600–2000 m, confirming that these routes are consistent with the known ocean circulation patterns. Our results were supported by multiple sources: (i) connectivity between the African coast and the Canary Islands for sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), (ii) panmixia of lobsters (Scyllarides latus and Palinurus elephas), and European conger eel (Conger conger); (iii) connectivity between Azores and Canary archipelagos for sponge (Phorbas fictitius); and (iv) observed drifting of crude oil from the Prestige oil tanker spill. These results should help guide future observational campaigns, as well as the interpretation of open-ocean transport patterns and the distribution of marine organisms and chemical tracers in the northeast Atlantic region.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"40-60"},"PeriodicalIF":0.0,"publicationDate":"2013-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2152611","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 54

Boundary-trapped, inhalant siphon and drain flows: Pipe entry revisited numerically 边界捕获，吸入虹吸和排水流动:管道入口重新访问数值

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-04-11 DOI: 10.1215/21573689-2082871

Peter A. Jumars

{"title":"Boundary-trapped, inhalant siphon and drain flows: Pipe entry revisited numerically","authors":"Peter A. Jumars","doi":"10.1215/21573689-2082871","DOIUrl":"10.1215/21573689-2082871","url":null,"abstract":"<div>\u0000 Flows produced in suspension feeding and tube and burrow ventilation cause and influence many exchange processes and chemical reactions. I investigated two geometries, a capillary drawing water far from any other boundary and a constant-diameter drain flush with the bottom. Flow descriptions just inside these inlets have relied on solutions to pipe entry that posit uniform entrance velocity. I substituted the more realistic boundary condition of constant volumetric outflow rate in finite-element models for 0.01 ≤ Re ≤ 2000. Re is the pipe Reynolds number, the product of mean capillary flow speed and capillary inside diameter (D) divided by kinematic viscosity of the fluid. For the smallest Re in both geometries, axial velocity reached 99% of its maximal value at a distance 0.2725D into the entry—not the 0.619 D found with uniform entrance velocity—and flow entering the capillary originated from a small, cylindrical region centered on the pipe axis. Axial flow velocities approaching the inlets therefore decreased away from the opening more slowly than predicted by simple convergence. For Re >330, flow converging on the capillary found traction on its outer wall (an apparent Coandă effect), and flow separation had major effects inside. Flow entering the siphon at these high Re values originated below the capillary entrance, and subsequent decrease in Re failed to dislodge the flow from its boundary-trapped state. Such hysteresis and flow bifurcation is unusual at low Reynolds numbers and could affect suspension feeders that deploy siphons and water samplers that use suction.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"21-39"},"PeriodicalIF":0.0,"publicationDate":"2013-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2082871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

On the global estimates of geostrophic and Ekman surface currents 地转和埃克曼表面流的全球估计

Limnology and Oceanography: Fluids and Environments Pub Date : 2013-02-21 DOI: 10.1215/21573689-2071927

Joël Sudre, Christophe Maes, Véronique Garçon

{"title":"On the global estimates of geostrophic and Ekman surface currents","authors":"Joël Sudre, Christophe Maes, Véronique Garçon","doi":"10.1215/21573689-2071927","DOIUrl":"10.1215/21573689-2071927","url":null,"abstract":"<div>\u0000 Surface currents in oceanic environments are of crucial importance because they transport momentum, heat, salt, and tracers over large distances that regulate both the local and large-scale climate conditions, and because they contribute to the Lagrangian displacement of floating material, ranging from living resources to marine pollution. In recent decades, the understanding of surface currents has benefited from the opportunity of observing sea level and wind stress via satellite-derived measurements. Combining these parameters into geostrophic and wind-driven components provides an estimate of surface currents with a quarter-degree horizontal resolution at a global scale and at a daily time scale. In the present study, improvements are made on the consideration of the time dependence of the main parameters implied in the determination of the Ekman wind-driven component, and on the treatment of the equatorial singularity. The resulting Geostrophic and Ekman Current Observatory (GEKCO) estimates were validated with independent observations from both Lagrangian and Eulerian perspectives. The statistics of comparison were significant over the globe for the 2000–2008 period. The only exception was the estimation of meridional current along the equator, which requires further developments of the dynamic model and, probably, more accurate measurements. Applications using our GEKCO surface current estimates in cross-disciplinary approaches from physical oceanography to marine ecology are presented and discussed.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"1-20"},"PeriodicalIF":0.0,"publicationDate":"2013-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2071927","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 123

Wind-driven physical processes and sediment characteristics affect the distribution and nutrient limitation of nearshore phytoplankton in a stratified low-productivity lake 海风驱动的物理过程和沉积物特征影响了层状低生产力湖泊近岸浮游植物的分布和营养限制

Limnology and Oceanography: Fluids and Environments Pub Date : 2012-12-19 DOI: 10.1215/21573689-1964968

Hélène Cyr, Melissa A. Coman

{"title":"Wind-driven physical processes and sediment characteristics affect the distribution and nutrient limitation of nearshore phytoplankton in a stratified low-productivity lake","authors":"Hélène Cyr, Melissa A. Coman","doi":"10.1215/21573689-1964968","DOIUrl":"10.1215/21573689-1964968","url":null,"abstract":"<div>\u0000 Wind-driven physical processes are expected to affect the distribution and composition of phytoplankton communities and to determine their access to nearshore nutrients. We examined the effect of wind-driven physical processes (surface waves, seiching activity) on the distribution of phytoplankton biomass, their growth rate, and nutrient limitation. We sampled nearshore and offshore phytoplankton on 11 days during the pre-, early-, mid-, and late-stratification periods. Phytoplankton biomass (measured as chlorophyll concentration) accumulated downwind, but growth rate was usually higher at upwind than at downwind sites. This suggests that the quantity and quality of algal food sources for higher trophic levels may vary in predictable but opposite ways. Wind-driven surface waves and upwelling activity were associated with changes in phytoplankton nutrient limitation in nearshore areas, but these differences were site specific. Our results suggest that wind-driven physical processes and sediment characteristics are both important in determining internal nutrient loading and phytoplankton nutrient limitation in nearshore areas. On windy days, nutrient limitation of offshore phytoplankton at the lake surface was always related to the conditions found upwind, suggesting rapid exchanges between nearshore and offshore areas. Wind-driven physical processes affect the distribution and nutrient limitation of phytoplankton in lakes, and are likely to influence the efficiency of trophic transfers in planktonic communities. These wind-driven processes should be included more specifically into food web models.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"2 1","pages":"93-108"},"PeriodicalIF":0.0,"publicationDate":"2012-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-1964968","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

The effect of fluid viscosity, habitat temperature, and body size on the flow disturbance of Euchaeta 流体粘度、栖息地温度和体型对真毛藻流动扰动的影响

Limnology and Oceanography: Fluids and Environments Pub Date : 2012-11-19 DOI: 10.1215/21573689-1894514

Kimberly B. Catton, Donald R. Webster, Jeannette Yen

{"title":"The effect of fluid viscosity, habitat temperature, and body size on the flow disturbance of Euchaeta","authors":"Kimberly B. Catton, Donald R. Webster, Jeannette Yen","doi":"10.1215/21573689-1894514","DOIUrl":"10.1215/21573689-1894514","url":null,"abstract":"<div>\u0000 The spatial extent and temporal decay of copepod-generated hydrodynamic disturbances during cruise and escape behavior were examined using the particle image velocimetry technique combined with theoretical models. Our study compared results for two species in the genus Euchaeta: the larger E. elongata living in colder water of higher viscosity versus the smaller E. rimana living in warmer water of lower viscosity. We expected that body size and viscosity would work in opposite directions in shaping the spatial and temporal properties of the hydrodynamic disturbances generated by these two copepod species. We found that the spatial extent of the copepod-induced hydrodynamic signal in front of the copepods during cruising was equivalent, with the peak strength of the signal to preferred prey showing no significant difference. In contrast, the spatial extent and strength of the hydrodynamic disturbance during escape were larger for E. elongata, although the decay time of the flow disturbance to a threshold value was equivalent between the species. Importantly, the observation of vortex rings during escape for Euchaeta strongly supports the appropriateness of the impulsive stresslet model over the impulsive Stokeslet model. Moreover, our empirical data discount the validity of using a sphere in creeping flow to model copepod–fluid interactions. Rather, these results suggest a complicated interaction of fluid viscosity, body size, and swimming speed for the genus Euchaeta that partially explains the adaptations to the local environmental conditions.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"2 1","pages":"80-92"},"PeriodicalIF":0.0,"publicationDate":"2012-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-1894514","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66026992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 12

Dispersal, eddies, and the diversity of marine phytoplankton 海洋浮游植物的扩散、漩涡和多样性

Limnology and Oceanography: Fluids and Environments Pub Date : 2012-11-08 DOI: 10.1215/21573689-2373515

Sophie Clayton, Stephanie Dutkiewicz, Oliver Jahn, Michael J. Follows

{"title":"Dispersal, eddies, and the diversity of marine phytoplankton","authors":"Sophie Clayton, Stephanie Dutkiewicz, Oliver Jahn, Michael J. Follows","doi":"10.1215/21573689-2373515","DOIUrl":"10.1215/21573689-2373515","url":null,"abstract":"<div>\u0000 We examined the role of physical dispersal in regulating patterns of diversity of marine phytoplankton in the context of global ocean simulations at eddy-permitting and coarse resolutions. Swifter current speeds, faster dispersal, and increased environmental variability in the higher-resolution model enhanced local diversity almost everywhere. In the numerical simulations, each resolved phytoplankton type was characterized as “locally adapted” at any geographical location (i.e., having net local biological production and physical export) or “immigrant” (i.e., net local biological loss but a population sustained by immigration via physical transport). Immigrants accounted for a higher fraction of the total diversity in the equatorial and subtropical regions, where the exclusion timescale is long relative to the physical transport between “provinces.” Hotspots of diversity were associated with western boundary currents and coastal upwelling regions. The former had high locally adapted diversity within the core of the current system, maintained by confluence of upstream populations and the induction of nutrient resources, as well as environmental variability associated with mesoscale eddies. Downstream of strong nutrient sources, convergence of populations led to immigrant-dominated diversity. The numerical simulations provide testable predictions of patterns in diversity and hypotheses regarding the mechanisms that control them. Molecular approaches to characterizing diversity in microbial populations will provide a means to test these hypotheses.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"3 1","pages":"182-197"},"PeriodicalIF":0.0,"publicationDate":"2012-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-2373515","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66027011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 86

Observations of mean and turbulent flow structure in a free-floating macrophyte root canopy 自由漂浮的大型植物根冠层的平均和湍流结构观测

Limnology and Oceanography: Fluids and Environments Pub Date : 2012-07-12 DOI: 10.1215/21573689-1631580

Maureen A. Downing-Kunz, Mark T. Stacey

{"title":"Observations of mean and turbulent flow structure in a free-floating macrophyte root canopy","authors":"Maureen A. Downing-Kunz, Mark T. Stacey","doi":"10.1215/21573689-1631580","DOIUrl":"10.1215/21573689-1631580","url":null,"abstract":"<div>\u0000 Free-floating macrophytes often grow in dense mats, and their feathery, unanchored roots form canopies at the water surface that can affect stream hydraulics and water quality. This study examines the physical interactions between a common species of free-floating macrophyte, water hyacinth (Eichhornia crassipes), and surrounding water flow to better understand the hydrodynamic effects of free-floating macrophyte root canopies. Experiments in an open-channel flow chamber were conducted to examine flow fields through and around root canopies. The presence of the root canopy in the channel caused deflection of flow around and reduced velocities within the canopy. Increased Reynolds stress and turbulent kinetic energy were observed beyond 50% of canopy length, culminating in a large wake region immediately downstream. Vertical profiles of mean streamwise water velocity beyond 50% of canopy length exhibited inflection points, suggesting mixing layer development analogous to mixing layers in leaf canopies of terrestrial and aquatic vegetation. The vertical turbulent structure exhibited sweeps, coherent vortices, and increased mixing efficiency along the canopy edge. Although turbulent mixing increased outside the root canopy, limited turbulent exchange between the root canopy and the open water was observed. This implies low momentum flux across the canopy–water interface, and therefore we expect residence time in the root canopy to be dominated by horizontal advection.\u0000 </div>","PeriodicalId":100878,"journal":{"name":"Limnology and Oceanography: Fluids and Environments","volume":"2 1","pages":"67-79"},"PeriodicalIF":0.0,"publicationDate":"2012-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1215/21573689-1631580","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66026980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22