LSU’s Sibel Bargu, along with her former graduate student Ana Garcia, from the Department of Oceanography and Coastal Sciences in LSU’s School of the Coast & Environment, has discovered toxic algae in vast, remote regions of the open ocean for the first time. The recent findings were published in the Nov. 8 edition of one of the most prestigious scientific journals, the Proceedings of the National Academy of Sciences, or PNAS.
Harmful algal blooms, or HABs, are reported as increasing both geographically and in frequency along populated coastlines. Bargu’s research shows that the ubiquitous diatom Pseudo-nitzschia – an alga that produces the neurotoxin, domoic acid, or DA, in coastal regions – actually also produces DA at many locations in the open Pacific. The presence of these potent toxins in deep water environments is worrisome, given that in coastal waters, where the phenomenon has been studied, DA can enter the food chain, forcing the closure of some fisheries and poisoning marine mammals and birds that feed on the contaminated fish. The main concern, though, is that the adding of iron to ocean waters – one of the most commonly proposed strategies to reduce global warming – appears now to likely result in promoting toxic blooms in the ocean.
Because both natural and artificial iron additions in open ocean waters can result in phytoplankton blooms in large areas of the sea that are deficient in the metal, and also because phytoplankton take up carbon dioxide and iron in addition to seawater, it has been suggested as a remedy to combat global warming. Basically, the new growth of photosynthetic cells draws carbon dioxide into the sea, reducing the amount of this gas in the atmosphere and thus reducing its warming effect. However, Pseudo-nitzschia-like cells have been known for a while to be common responders in a number of iron fertilization experiments conducted at sea over more than a decade.
To address the possible presence of the neurotoxin DA in regions where Pseudo-nitzschia occur in the open ocean, Bargu and one of the paper’s co-authors, Mary Silver from University of California, Santa Cruz, or UCSC, sought and received funding in 2007 from National Science Foundation to look for the toxin producers in the open sea. They joined Ken Bruland, professor of ocean Sciences at UCSC, on a research cruise to study iron chemistry in oceanic waters of the Gulf of Alaska. During this expedition, they collected water samples and found the algae and its toxin in nearly all of the natural oceanic environments throughout the region. This prompted them to examine older, stored samples from other sites around the Pacific, and again they found the toxin in most samples.
Then, with the help of Kenneth Coale, director of Moss Landing Marine laboratories and principal investigator on several cruises that conducted classic iron enrichment experiments in the Pacific, they retrieved samples and found both Pseudo-nitzschia and substantial amounts of toxin. Their findings show that iron enrichment indeed promotes high levels of toxins in the open sea, sometimes as high as those in coastal regions, where deaths of seabirds and mammals occur. The authors of this PNAS paper also noted that iron enrichments can occur naturally, suggesting that the high levels of toxins may also have occurred when iron was added by wind-blown dust and other climate and geological processes.
Bargu, a principal investigator on the Gulf of Alaska phytoplankton study, was responsible for identification of all the Pseudo-nitzschia species and the toxin testing in the project. In addition to Bargu and her former graduate student Garcia, the coauthors of the PNAS paper include Silver, Coale, Ken Bruland, Susan Coale and Kathryn Roberts at UCSC; and Claudia Benitez-Nelson and Emily Sekula-Wood at the University of South Carolina. This research was funded by the National Science Foundation, U.S. Department of Energy and the U.S. Office of Naval Research.
Impacts from HABs have been also the subject of regional interest in the northern Gulf of Mexico for many decades. Among the many HAB impacts in this region, those due to coastal blooms of the diatoms genus Pseudo-nitzschia and the associated DA are of particular concern. Studies of Louisiana coastal and estuarine waters have documented the occurrence of toxic Pseudo-nitzschia, often at bloom concentrations with annual occurrence of spring blooms exceeding a million toxic cells per liter. Current thinking suggests the annual spring peak in Pseudo-nitzschia probably occurs in response to the spring flood of the Mississippi River.
An ongoing study by Bargu’s lab is studying the extent of Pseudo-nitzschia and its toxin, finding that that DA-producing Pseudo-nitzschia are frequently present in nearshore and offshore Louisiana waters. Her research group has already detected high levels of DA in water and at moderate levels in gulf menhaden from Terrebone Bay, La., the second largest fishery in the U.S.
Bargu is specifically studying the impact of these blooms on the food web, trying to better understand the impact such algae growth can have on the next level up the food chain. She argues that it is now critical to understand the extent of toxic algal blooms in the area and their causes.
“Given our dependence on the seafood industry here, it is critical to recognize and then reduce the causes of toxic algal blooms,” she said. “Only by monitoring and addressing the causes of the blooms can we safeguard our fisheries and the people who make a living working in them.”
For more information about LSU’s School of the Coast & Environment, visit http://www.sce.lsu.edu/.Ashley Berthelot
Ashley Berthelot | EurekAlert!
Further reports about: > Algae > Environment > Gulf of Maine region > Oceanography > PNAS > Pacific coral > Pseudonitzschia > Science TV > Silver Gamer > Water Snake > algal bloom > carbon dioxide > coastal regions > food chain > global warming > ocean water > open ocean > toxic algal blooms > toxic metals
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences