Small-scale convective turbulence constrains microbial patchiness

Abstract Microbes play a primary role in aquatic ecosystems and biogeochemical cycles. Patchiness is a critical component of these activities, influencing biological productivity, nutrient cycling and dynamics across trophic levels. Incorporating spatial dynamics into microbial models is a long-standing challenge, particularly where small-scale turbulence is involved. Here, we combine a realistic simulation of turbulence with an individual-based microbial model to test the key hypothesis that the coupling of motility and turbulence drives intense microscale patchiness. We find that such patchiness is depth-structured and requires high motility: Near the fluid surface, strong convective turbulence overpowers motility, homogenising motile and non-motile microbes equally. In deeper, thermocline-like conditions, highly motile microbes are up to 1.6-fold more patch-concentrated than non-motile microbes. Our results demonstrate that the delicate balance of turbulence and motility that triggers micro-scale patchiness is not a ubiquitous consequence of motility, and that the intensity of such patchiness in real-world conditions is modest.

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Investigating microscale patchiness of motile microbes driven by the interaction of turbulence and gyrotaxis in a 3D simulated convective mixed layer.

10.21203/rs.3.rs-152503/v2 ◽

2021 ◽

Author(s):

Alexander Christensen ◽

Matthew Piggott ◽

Erik van Sebille ◽

Maarten van Reeuwijk ◽

Samraat Pawar

Keyword(s):

Mixed Layer ◽

Fluid Model ◽

Spatial Dynamics ◽

Critical Factor ◽

Trophic Levels ◽

Small Scale ◽

Swimming Velocity ◽

Primary Role ◽

Fluid Surface ◽

Convective Mixed Layer

Abstract Microbes play a primary role in aquatic ecosystems and biogeochemical cycles. Spatial patchiness is a critical factor underlying these activities, influencing biological productivity, nutrient cycling and dynamics across trophic levels. Incorporating spatial dynamics into microbial models is a long-standing challenge, particularly where small-scale turbulence is involved. Here, we combine a fully 3D direct numerical simulation of convective mixed layer turbulence, with an individual-based microbial model to test the key hypothesis that the coupling of gyrotactic motility and turbulence drives intense microscale patchiness. The fluid model simulates turbulent convection caused by heat loss through the fluid surface, for example during the night, during autumnal or winter cooling or during a cold-air outbreak. We find that under such conditions, turbulence-driven patchiness is depth-structured and requires high motility: Near the fluid surface, intense convective turbulence overpowers motility, homogenising motile and non-motile microbes approximately equally. At greater depth, in conditions analogous to a thermocline, highly motile microbes can be over twice as patch-concentrated as non-motile microbes, and can substantially amplify their swimming velocity by efficiently exploiting fast-moving packets of fluid. Our results substantiate the predictions of earlier studies, and demonstrate that turbulence-driven patchiness is not a ubiquitous consequence of motility but rather a delicate balance of motility and turbulent intensity.

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Effects of small-scale turbulence on lower trophic levels under different nutrient conditions

Journal of Plankton Research ◽

10.1093/plankt/fbq011 ◽

2010 ◽

Vol 32 (4) ◽

pp. 575-575

Author(s):

K. R. Iversen ◽

R. Primicerio ◽

A. Larsen ◽

J. K. Egge ◽

F. Peters ◽

...

Keyword(s):

Trophic Levels ◽

Small Scale ◽

Scale Turbulence ◽

Nutrient Conditions

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Effects of small-scale turbulence on lower trophic levels under different nutrient conditions

Journal of Plankton Research ◽

10.1093/plankt/fbp113 ◽

2009 ◽

Vol 32 (2) ◽

pp. 197-208 ◽

Cited By ~ 16

Author(s):

K. Rokkan Iversen ◽

R. Primicerio ◽

A. Larsen ◽

J. K. Egge ◽

F. Peters ◽

...

Keyword(s):

Trophic Levels ◽

Small Scale ◽

Scale Turbulence ◽

Nutrient Conditions

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Plastic Pollution and the Ecological Impact on the Aquatic Ecosystem

Handbook of Research on Environmental and Human Health Impacts of Plastic Pollution - Advances in Environmental Engineering and Green Technologies ◽

10.4018/978-1-5225-9452-9.ch005 ◽

2020 ◽

pp. 80-93 ◽

Cited By ~ 1

Author(s):

Irfan Rashid Sofi ◽

Javid Manzoor ◽

Rayees Ahmad Bhat ◽

Rafiya Munvar

Keyword(s):

Aquatic Ecosystems ◽

Ecological Impact ◽

Freshwater Ecosystems ◽

Trophic Levels ◽

Small Scale ◽

Plastic Pollution ◽

Marine Litter ◽

Plastic Debris ◽

Plastic Wastes ◽

The One

Plastic pollution in the environment is currently receiving worldwide attention. Improper dumping of disused or abandoned plastic wastes leads to contamination of the environment. Contamination by bulk plastics and plastic debris is currently the one of the most serious problems in aquatic ecosystems. In particular, small-scale plastic debris such as microplastics and nanoplastics has become a leading contributor to the pollution of marine and freshwater ecosystems. Over 300 million tons of plastic is produced annually, and around 75% of all marine litter is plastic. Plastic litter is widespread in aquatic ecosystems and comes from a variety of sources. The abundance of plastics, combined with their small size and subsequent association with plankton in the water column, allows for direct ingestion by aquatic biota at different trophic levels.

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Improving the Small Scale Turbulence Structure for Fluid Dynamics Computations

41st Aerospace Sciences Meeting and Exhibit ◽

10.2514/6.2003-195 ◽

2003 ◽

Author(s):

Rod Frehlich ◽

Robert Sharman

Keyword(s):

Fluid Dynamics ◽

Small Scale ◽

Turbulence Structure ◽

Scale Turbulence

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Similarity of dissipation and enstrophy in particle-induced small-scale turbulence

Physical Review Fluids ◽

10.1103/physrevfluids.5.014301 ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

Zhuo Wang ◽

Kun Luo ◽

Junhua Tan ◽

Dong Li ◽

Jianren Fan

Keyword(s):

Small Scale ◽

Scale Turbulence

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Role of large-scale advection and small-scale turbulence on vertical migration of gyrotactic swimmers

Physical Review Fluids ◽

10.1103/physrevfluids.4.124304 ◽

2019 ◽

Vol 4 (12) ◽

Author(s):

C. Marchioli ◽

H. Bhatia ◽

G. Sardina ◽

L. Brandt ◽

A. Soldati

Keyword(s):

Vertical Migration ◽

Large Scale ◽

Small Scale ◽

Scale Turbulence

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Fabrication of freestanding Pt nanowires for use as thermal anemometry probes in turbulence measurements

Microsystems & Nanoengineering ◽

10.1038/s41378-021-00255-0 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Hai Le-The ◽

Christian Küchler ◽

Albert van den Berg ◽

Eberhard Bodenschatz ◽

Detlef Lohse ◽

...

Keyword(s):

Room Temperature ◽

Fluid Velocity ◽

Current Mode ◽

Constant Current ◽

Small Scale ◽

Turbulence Measurements ◽

High Dynamic ◽

Scale Turbulence ◽

Constant Current Mode ◽

Pt Nanowires

AbstractWe report a robust fabrication method for patterning freestanding Pt nanowires for use as thermal anemometry probes for small-scale turbulence measurements. Using e-beam lithography, high aspect ratio Pt nanowires (~300 nm width, ~70 µm length, ~100 nm thickness) were patterned on the surface of oxidized silicon (Si) wafers. Combining wet etching processes with dry etching processes, these Pt nanowires were successfully released, rendering them freestanding between two silicon dioxide (SiO2) beams supported on Si cantilevers. Moreover, the unique design of the bridge holding the device allowed gentle release of the device without damaging the Pt nanowires. The total fabrication time was minimized by restricting the use of e-beam lithography to the patterning of the Pt nanowires, while standard photolithography was employed for other parts of the devices. We demonstrate that the fabricated sensors are suitable for turbulence measurements when operated in constant-current mode. A robust calibration between the output voltage and the fluid velocity was established over the velocity range from 0.5 to 5 m s−1 in a SF6 atmosphere at a pressure of 2 bar and a temperature of 21 °C. The sensing signal from the nanowires showed negligible drift over a period of several hours. Moreover, we confirmed that the nanowires can withstand high dynamic pressures by testing them in air at room temperature for velocities up to 55 m s−1.

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3–D Models of Galaxy Magnetic Fields with Spiral Shocks

Symposium - International Astronomical Union ◽

10.1017/s0074180900189752 ◽

1990 ◽

Vol 140 ◽

pp. 133-134

Author(s):

J. Panesar ◽

A.H. Nelson

Keyword(s):

Gas Flow ◽

Density Wave ◽

Shock Velocity ◽

Small Scale ◽

Hydrodynamic Simulation ◽

Dynamo Equation ◽

Scale Turbulence ◽

Wave Induced ◽

The Magnetic Field ◽

Stellar Density

We report here some preliminary results of 3–D numerical simulations of an α–ω dynamo in galaxies with differential rotation, small–scale turbulence, and a shock wave induced by a stellar density wave. We obtain the magnetic field from the standard dynamo equation, but include the spiral shock velocity field from a hydrodynamic simulation of the gas flow in a gravitational field with a spiral perturbation (Johns and Nelson, 1986).

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