Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nitrogen from pollution, natural sources causes growth of toxic algae, study finds

07.02.2013
Nitrogen in ocean waters fuels the growth of two tiny but toxic phytoplankton species that are harmful to marine life and human health, warns a new study published in the Journal of Phycology.

Researchers from San Francisco State University found that nitrogen entering the ocean -- whether through natural processes or pollution -- boosts the growth and toxicity of a group of phytoplankton that can cause the human illness Amnesic Shellfish Poisoning.


This is a scanning electron micrograph of the phytoplankton species Pseudo-nitzschia cuspidata (the long, thin needle-like objects).

Credit: Brian Bill/NOAA

Commonly found in marine waters off the North American West Coast, these diatoms (phytoplankton cells) of the Pseudo-nitzschia genus produce a potent toxin called domoic acid. When these phytoplankton grow rapidly into massive blooms, high concentrations of domoic acid put human health at risk if it accumulates in shellfish. It can also cause death and illness among marine mammals and seabirds that eat small fish that feed on plankton.

"Regardless of its source, nitrogen has a powerful impact on the growth of phytoplankton that are the foundation of the marine food web, irrespective of whether they are toxic or not," said William Cochlan, senior research scientist at SF State's Romberg Tiburon Center for Environmental Studies. "Scientists and regulators need to be aware of the implications of both natural and pollutant sources of nitrogen entering the sea."

Nitrogen can occur naturally in marine waters due to coastal upwelling, which draws cool, nutrient-rich water containing nitrate (the most stable form of nitrogen) from deeper depths into sunlit surface waters. Pollution, including agricultural runoff containing fertilizer and effluent from sewage plants, is also responsible for adding nitrogen, including ammonium and urea, to ocean waters, but in most regions these types of nitrogen occur at relatively low concentrations.

In laboratory studies, Cochlan and former graduate student Maureen Auro found that natural and pollution-caused nitrogen forms equally support the growth of the harmful Pseudo-nitzschia algae and cause the production of the domoic acid, but in all cases the natural form of nitrogen caused the most toxic cells.

They also found that these small diatoms became particularly toxic under low light levels – a condition that usually slows the growth of phytoplankton. The species, P. cuspidata, underwent an up to 50 fold increase in toxicity under low light levels compared to the conditions that are thought to normally favor phytoplankton growth.

Scientists already know that in some large-celled species of Pseudo-nitzschia their toxicity increases when the cells grow slower, but in previous studies the slowing of cellular growth was due to the limitation of vital nutrients, such as silicate. However Cochlan's latest study found that the toxicity of these small toxigenic diatoms is affected by the type of nitrogen they consume. He found that under low light levels -- leading to slow growth -- phytoplankton cells that were fed on naturally occurring nitrate were more toxic than cells that were fed on either urea or ammonium caused by pollution.

"Our results demonstrate that the reason for the growth of these specific harmful algal blooms off the coast of North America from British Columbia to California may in fact be due to totally natural causes," Cochlan said.

Such toxic algal blooms may be largely supported by the natural upwelling of nitrogen. However, Cochlan cautions that when the pattern of upwelling is weaker, nitrogen from pollution could play an important role in sustaining a "seed population" of harmful algae – a remnant that keeps the bloom going until upwelling resumes and the bloom is able to grow again and perhaps increase their toxic effect on the marine ecosystem.

"This is the first physiological study to look at the environmental conditions that promote both the growth and the toxicity of these small diatoms," Cochlan said. "The findings may shed light on why these microorganisms produce a potent neurotoxin and what the ecological advantage is for the phytoplankton producing it."

"Nitrogen Utilization and Toxin Production by Two Diatoms of the Pseudo-nitzschia pseudodelicatissima complex: P. cuspidata and P. fryxelliana," was published in the February 2013 issue of the Journal of Phycology. The paper was authored by Maureen E. Auro, a graduate of the marine biology master's program at SF State, and William P. Cochlan, senior research scientist at SF State's Romberg Tiburon Center for Environmental Studies.

The study was funded by the National Science Foundation's Ecology and Oceanography of Harmful Algal Blooms program (ECOHAB).

Elaine Bible | EurekAlert!
Further information:
http://www.sfsu.edu

More articles from Studies and Analyses:

nachricht New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg

nachricht Disarray in the brain
18.12.2017 | Universität zu Lübeck

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>