Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study may explain extreme algae growth in streams where they should starve

03.06.2011
A species of freshwater algae that lives in streams and rivers is able to colonize and dominate the bottoms of some of the world's cleanest waterways --precisely because they are so clear, according to a new study.

The alga, called Didymo for Didymosphenia geminata, does so with a little help from its friends -- in this case, bacteria-- which allow it to make use of nutrients like phosphorus.

Blooms of Didymo, also known as "rock snot," are made up of stalks that form thick mats on the beds of oligotrophic (low-nutrient) streams and rivers, says scientist P.V. Sundareshwar of the South Dakota School of Mines and Technology in Rapid City. Sundareshwar is the lead author of the paper, published on 28 May in Geophysical Research Letters, a journal of the American Geophysical Union.

"In recent decades, human activities have led to many uncommon environmental phenomena," he says. "Now we have Didymo."

The freshwater diatom has become notorious. Didymo has taken over oligotrophic rivers in North America and Europe. It has also invaded water bodies in the Southern Hemisphere, including those in New Zealand and Chile.

Because its blooms alter food webs and have the potential to impact fisheries, "Didymo presents a threat to the ecosystem and economic health of these watercourses," says Sundareshwar.

Algae blooms are usually linked with the input of nutrients that fuel the growth of microscopic aquatic plants. Didymo's ability to grow prolifically in waters where nutrients such as phosphorus are in short supply had puzzled scientists.

Environmental managers had tried to mitigate Didymo blooms and predict their spread. But how the diatoms sustained such high growth in oligotrophic systems was unknown.

In the study, Sundareshwar and colleagues revealed that Didymo is able to concentrate phosphorus from the water.

The scientists conducted their research in Rapid Creek, an unpolluted mountain stream in western South Dakota where Didymo was first observed in 2002. The creek regularly has Didymo blooms, with 30 to 100 percent of the streambed covered with Didymo over an area up to ten kilometers (6.2 miles) long.

Didymo thrives in Rapid Creek through biogeochemical processes in biofilms in the mats. As Didymo mats develop, new stalks develop at the surface and older stalks-which have already bound phosphorus-are displaced to the mats' inner regions.

Phosphorus is available to Didymo thanks to the activity of the bacteria that live inside these mats.

"This study solves the puzzle of how Didymo can produce such large blooms in low-nutrient rivers and streams," says Tim Kratz, program director in the National Science Foundation's (NSF) Division of Environmental Biology.

"It has uncovered the fascinating mechanism by which Didymo 'scrubs' phosphorus from a stream or river," says Kratz, "then creates a microenvironment that allows microbes to make this nutrient available for Didymo's growth."

The concentration of phosphorus on Didymo mats far exceeds the level that was expected based on the nutrient content of surface waters, says Sundareshwar. "The ability of the mats to store phosphorus is in turn tied to the availability of iron in the water."

Didymo cells adsorb (collect on their surfaces) both iron and phosphorus. Then bacterial processes in the mat interact with iron to increase the biological availability of phosphorus.

The process results in abundant phosphorus for cell division, "and hence," says Sundareshwar, "a resolution to the paradox of Didymo blooms in oliogotrophic streams and rivers."

The result may help managers identify water bodies susceptible to Didymo blooms, and develop management strategies.

"It also has the potential to lead to discoveries that may stem this organism's prolific growth in rivers around in the world," says Sundareshwar.

This study was funded by NSF and the State of South Dakota Carbon Scientist fund.

Notes for Journalists
Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper by Sundareshwar et al. by clicking on this link:

http://dx.doi.org/10.1029/2010GL046599

Or, you may order a copy of the paper by emailing your request to Maria-Jose Vinas at mjvinas@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither this paper nor this press release are under embargo.

Title:
"Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers"
Authors:
P. V. Sundareshwar, S. Upadhayay, M. Abessa, S. Honomichl, C. Sandvik, and A. Trennepohl:

Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA;

B. Berdanier: Deparment of Civil and Environmental Engineering, South Dakota State University, Brookings, South Dakota, USA;

S. A. Spaulding: INSTAAR, U.S. Geological Survey, Boulder, Colorado, USA.

Contact information for the author:
P. V. Sundareshwar: pvs@sdsmt.edu, +1 (605) 394-2492

Maria-Jose Vinas | American Geophysical Union
Further information:
http://www.agu.org

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>