Matisse’s glass-enclosed liquid sculptures contain an object whose movement through the liquid creates whorls that can be seen only because elongated particles trailing the object align with the direction of the current; light reflects off the particles, making the current visible to the viewer.
Researchers at MIT recently demonstrated that this same phenomenon is responsible for the swirling patterns scientists typically see when they agitate a flask containing microbes in water; many microbes are themselves elongated particles that make the whorls visible. More importantly, they say this phenomenon occurs in the ocean when elongated microbes caught in a current align horizontally with the ocean surface, affecting how much light goes into the ocean and how much bounces off as backscatter. Because many ocean microbes, like large phytoplankton, have either an elongated shape or live in communities of long chains, this orientation to ocean currents could have a substantial effect on ocean light — which in turn influences photosynthesis and phytoplankton growth rates — as well as on satellite readings of light backscatter used to inform climate models or assess algal blooms.
In a quiescent ocean, phytoplankton are randomly oriented and light filters through easily. This random arrangement is usually assumed in models of light propagation in the ocean and in satellite readings. But fluid flow can change things.
“Even small shear rates can increase backscattering from blooms of large phytoplankton by more than 30 percent,” said Roman Stocker, Professor of Civil and Environmental Engineering at MIT and lead author on a paper about this work. “This implies that fluid flow, which is typically neglected in models of marine optics, may exert an important control on light propagation, influencing the rates of carbon fixation and how we estimate these rates via remote sensing.”
Another consideration is microbial size. Very small microbes (less than 1 micrometer in diameter) don’t align with the ocean current no matter what their shape. “These very small things don’t align because they are too vigorously kicked around by water molecules in an effect called Brownian motion,” said Stocker, who studies the biomechanics of the movements of ocean microbes, often in his own micro-version of a Kalliroscope called microfluidics. He recreates an ocean environment in microfluidic devices about the size of a stick of gum and uses videomicroscopy to trace and record the microbes’ movements in response to food and current.
In this case, however, the research methodology was observation, followed by mathematical modeling (much of which was handled by graduate student Marcos, who created a model that coupled fluid mechanics with optics), and subsequent experimentation carried out by graduate students Mitul Luhar and William Durham using a tabletop-sized device.
But the impetus for the research was an observance of swirling microbes in a flask of water and a question posed by Justin Seymour, a former postdoctoral fellow at MIT. “Justin walked up to me with a flask of microbes in water, shook it, and asked me what the swirls were,” said Stocker. “Now we know.”
In addition to Seymour, who is now a research fellow at the University of Technology Sydney, other co-authors on the paper are Marcos, Luhar and Durham; Professor James Mitchell of Flinders University in Adelaide, Australia; and Professor Andreas Macke of the Leibniz Institute for Tropospheric Research in Germany.
Next steps: The researchers plan to test this mechanism in the field in a local environment suitable for experimentation, most likely a nearby lake.
Funding: Funding was provided by grants from the National Science Foundation and the Australian Research Council and by a Hayashi Grant from MIT’s International Science and Technology Initiatives Program.
Source: “Microbial alignment in flow changes ocean light climate,” by Marcos, Justin Seymour, Mitul Luhar, William Durham, James Mitchell, Andreas Macke and Roman Stocker, in PNAS Early Edition online Feb. 21, 2011.
Written by: Denise Brehm, Civil and Environmental Engineering
Denise Brehm | EurekAlert!
Plant seeds survive machine washing - Dispersal of invasive plants with clothes
11.09.2018 | Gesellschaft für Ökologie e.V.
Air pollution leads to cardiovascular diseases
21.08.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
The Fraunhofer FEP has been involved in developing processes and equipment for cleaning, sterilization, and surface modification for decades. The CleanHand Network for development of systems and technologies to clean surfaces, materials, and objects was established in May 2018 to bundle the expertise of many partnering organizations. As a partner in the CleanHand Network, Fraunhofer FEP will present the Network and current research topics of the Institute in the field of hygiene and cleaning at the parts2clean trade fair, October 23-25, 2018 in Stuttgart, at the booth of the Fraunhofer Cleaning Technology Alliance (Hall 5, Booth C31).
Test reports and studies on the cleanliness of European motorway rest areas, hotel beds, and outdoor pools increasingly appear in the press, especially during...
The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.
This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.
Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...
Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.
"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...
A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.
Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...
Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.
21.09.2018 | Event News
03.09.2018 | Event News
27.08.2018 | Event News
25.09.2018 | Life Sciences
25.09.2018 | Life Sciences
25.09.2018 | Life Sciences