Navigation Links
MIT research could help predict red tide
Date:2/19/2009

CAMBRIDGE, Mass.--Not far beneath the ocean's surface, tiny phytoplankton swimming upward in a daily commute toward morning light sometimes encounter the watery equivalent of Rod Serling's Twilight Zone: a sharp variation in marine currents that traps billions of these single-celled organisms and sends them tumbling until a shift in wind or tide alters the currents and sets them free.

Scientists are aware of these thin layers of single-celled creatures and their enormous ecological ramifications, but until now, they knew little about the mechanisms responsible for their formation.

The explanation by researchers in MIT's Department of Civil and Environmental Engineering of how these common, startlingly dense layers of photosynthetic phytoplankton form, moves the scientific community a step closer to being able to predict harmful algal blooms, a well-known example of which is red tide. The work also opens new perspectives on other phenomena, like predatory feeding by larger organisms at these ecological hotspots.

"Phytoplankton are incredibly small. You would have to stack about 10 back to back to equal the width of a single human hair," said PhD student William Durham, co-author on a paper appearing in the Feb. 20 issue of Science. "But despite their small size, they play an outsized role in the environment: they form the base of the marine food web and cumulatively produce half the world's oxygen. Many species can swim, but this fact is often neglected by researchers because phytoplankton are slow compared to ocean currents. However, we have shown that their motility can play a crucial role by concentrating them into dense assemblages, known as thin layers."

In the Science paper, Durham, Professor Roman Stocker and University of Arizona physics Professor John Kessler explain how adjacent layers of water moving at different speeds produce a "shear" flow that traps the phytoplankton as they swim into it. These layers form in the top 50 meters of the ocean and can be anywhere from a few centimeters to a couple of meters thick, span several kilometers horizontally and last hours, days or weeks.

"Our research pinpoints a mechanism for the formation of these thin layers of phytoplankton, which are analogous to watering holes in a savanna localized areas of concentrated resources that draw a wide range of organisms and thus play a disproportionate role in the ecological landscape," said Stocker, the Doherty Assistant Professor of Ocean Utilization at MIT.

Because motile phytoplankton have different morphologies and swimming abilities, one species may be able to swim through a layer of shear that will capture another. This means that each species could be trapped in a different level of shear, creating a sort of oceanic layered-cake effect, a boon for zooplankton or young fish that feed on specific species.

And when a toxic species of phytoplankton gets trapped in a thin layer, that layer can spawn a harmful algal bloom an explosion in the population of toxic phytoplankton that sickens or kills the larger animals that ingest the cells. Harmful algal blooms are a major source of social and economic concern, particularly near coastal areas, because they are becoming more frequent and cause billions of dollars in annual losses to fishing and recreational industries worldwide.

In a perspective piece accompanying the paper in Science, scientist Daniel Grnbaum of the University of Washington writes: "The authors demonstrate a sort of Peter Principle for algae migrating in shear: cells swim up until they reach their level of instability. At this critical shear level, cells can swim in, but they cannot swim out. The resulting aggregation, in what is arguably an unfavorable microenvironment, may have widespread consequences, as harmful blooms of toxic algae often take the form of thin layers."

Using video-microscopy, Durham and Stocker were able to track the movements of individual cells as they become trapped in the layers of shear. They also modeled the movements of the swimming cells mathematically and proved that they cannot escape these layers. Once trapped, they're at the mercy of the flow, and must wait for the shear to decrease before they can swim out and exit the Twilight Zone.


'/>"/>

Contact: Elizabeth Thomson
thomson@mit.edu
617-258-5402
Massachusetts Institute of Technology
Source:Eurekalert

Related medicine news :

1. Women less likely to receive critical care after a stroke, MSU researchers find
2. Physical activity guidelines are too confusing, say researchers
3. Toxic Element Research Foundation Announces Its Latest Worldwide Educational Programs for Health Professionals and Patients
4. Society for Womens Health Research and MITA Promote Greater Awareness of Medical Imaging to Diagnose Womens Coronary Artery Disease
5. Research Brings New Hope to Multiple Sclerosis Patients
6. Study calls for increased research in flu transmission to prepare for pandemic flu outbreak
7. Research increases possibilities of personalizing treatment of infant osteosarcoma
8. Two Scientists Honored with MetLife Foundation Awards for Medical Research in Alzheimers Disease
9. The Canadian Foundation for Global Health Announces a Research and Development Partnership with Medizone International, Inc.
10. Apple's iPod Touch Joins the iPhone as a Stuttering Therapy Tool At Hollins Communications Research Institute
11. Rice Universitys Baker Institute experts available to discuss stem cell research, recommendations
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/13/2017)... ... October 13, 2017 , ... PurhealthRX , a leading Health and Nutrition ... the Purzorb™process to full spectrum CBD oil will revolutionize the rapidly growing CBD market ... can be easily incorporated into liquid products, while reducing costs to end users. , ...
(Date:10/13/2017)... ... October 13, 2017 , ... Apple Rehab Shelton Lakes , ... mock evacuation of the facility as part of a disaster drill on October 3rd. ... EMS and Shelton City Emergency Manager, as well as the Connecticut Long Term ...
(Date:10/13/2017)... ... October 13, 2017 , ... Ellevate Network, the leading ... to advocate for action towards gender equality at their inaugural Summit in New York ... globe, and reached a social audience of over 3 million. To watch the Mobilize ...
(Date:10/13/2017)... ... October 13, 2017 , ... Talented host, actor Rob Lowe, ... in a new episode of "Success Files," which is an award-winning educational program ... investigates each subject in-depth with passion and integrity. , Sciatica occurs when the ...
(Date:10/13/2017)... (PRWEB) , ... October 13, 2017 , ... “America On ... Christian identity. “America On The Brink” is the creation of published author, William ... several great-grandchildren. As a WWII veteran, he spent thirty years in the Navy. ...
Breaking Medicine News(10 mins):
(Date:9/27/2017)...  Commended for their devotion to personalized service, SMP Pharmacy ... one in the South Florida Business Journal,s 50 Fastest-Growing Companies, ... list, the national specialty pharmacy has found its niche.  To ... soon be honored by SFBJ as the 2017 Power Leader ... to receive his award in October, Bardisa said of the ...
(Date:9/25/2017)... --  Montrium , an industry leader in powerful ... Trial Master Files & Inspection Readiness Conference ( ... Services has selected eTMF Connect to ... a leading European contract research organization (CRO), will ... enable greater collaboration with sponsors, improve compliance and ...
(Date:9/23/2017)... 22, 2017 Janssen Biotech, Inc. (Janssen) announced ... from the U.S. Food and Drug Administration (FDA) for ... for the treatment of moderately to severely active rheumatoid ... data are needed to further evaluate the safety of ... RA. "We ...
Breaking Medicine Technology: