Diatoms Reveal Freshwater Pollution

Researchers in India have demonstrated that microscopic aquatic creatures could be used as the ecological equivalent of a canary in a coalmine for assessing inland freshwater lakes and ponds. Writing in the World Review of Science, Technology and Sustainable Development the team explains how diatoms respond badly to pollutants and sewage contamination.

Bijaya Kumar Padhi, Jnanendra Rath, and Pratap Kumar Padhy of the Visva-Bharati University, in Santiniketan, India, have looked at the ecological responses of diatoms to pollution and nutrient enrichment, caused by domestic and municipal sewage, in five freshwater ponds. Absent diatom species were present in some heavily polluted lakes, while raised levels of nutrients boost numbers of other species. They suggest that a Biological Index for Diatoms could be used as a simple biological method for monitoring water quality that avoids the need for sophisticated chemical analysis.

Rapid urbanization and economic development have resulted in unfavorable changes in the hydrology and ecology of freshwater systems, which are felt most acutely in the developing world. The researchers explain that the remediation and protection of freshwater ecosystems is increasingly important but water quality management requires reliable long-term data on water quality and how remediation work affects the water. Moreover, information about natural, baseline, conditions in undisturbed ponds, lakes and rivers is needed against which polluted bodies of water undergoing remediation might be gauged.

Natural changes in environmental conditions, such as flow rate, water temperature, dissolved oxygen, and food resources exert direct control on the population dynamics of aquatic organisms, which gives rise to characteristic biological communities within different ecosystems. However, pollution and other human activities also disturb these community profiles significantly and so can provide such a measure.

Diatoms are important contributors to the primary production in aquatic ecosystems, sitting at the bottom of the food chain. They are eukaryotic algae, commonly unicellular, although they do exist as filamentous colonies and are good indicators of the environmental integrity, the researchers explain. They have several advantages over other indicators, the team adds.

First, they are readily dispersed and can invade a variety of habitats. They are relatively easy to sample and such sampling has negligible impact on the ecosystem during collection. Their "response" time to variation in environmental conditions lies between bacteria (change hourly) and bigger invertebrates (change over the course of months). Finally, diatoms are sensitive to very subtle changes in environmental conditions and/or disturbances that may not visibly affect other communities, or may only affect other communities at greater levels of disturbance.

The team's evaluation of diatom monitoring of five freshwater bodies was consistent with more conventional physical and chemical determinations carried out in parallel. Diatoms usually grow better in unpolluted ponds and streams and this preliminary investigation suggests that they could be useful for biological monitoring of pollution levels and ecosystem integrity in the short and potentially in the long-term once seasonal studies confirm the preliminary results.

Bijaya Kumar Padhi, Jnanendra Rath, Pratap Kumar Padhy. Diatoms for assessing the ecological condition of inland freshwater bodies. World Review of Science, Technology and Sustainable Development, 2010; 7 (4): 352 DOI: 10.1504/WRSTSD.2010.032743

Clues from Green Algae on the Origin of Males and Females

A multicellular green alga, Volvox carteri, may have finally unlocked the secrets behind the evolution of different sexes. A team led by researchers at the Salk Institute for Biological Studies has shown that the genetic region that determines sex in Volvox has changed dramatically relative to that of the closely related unicellular alga Chlamydomonas reinhardtii.

Their findings, which will be published in the April 16th issue of the journal Science, provide the first empirical support for a model of the evolution of two different sexes whereby expansion of a sex-determining region creates genetic diversity followed by genes taking on new functions related to the production of male and female reproductive cells termed gametes.

"Until now, sex-determining chromosomes had generally been viewed as regions of decay, steadily losing genes that are not involved in sexual reproduction," explains James Umen, Ph.D., assistant professor in the Plant Molecular and Cellular Biology Laboratory at the Salk Institute, who led the team conducting the study. "Our study shows the opposite-that such regions can expand and generate new genetic material much more rapidly than the rest of the genome."

Most multicellular organisms such as plants and animals have two distinct sexes with females producing large immotile eggs and males producing small motile sperm. While unicellular organisms can also reproduce sexually, the two sexes of single-celled species are typically indistinguishable from each other and are thought to represent an ancestral or early evolutionary state. However, the large distances that separate plants or animals from their closest unicellular relatives have precluded understanding the evolutionary transition to male-female dimorphism.

"In unicellular organisms like Chlamydomonas, the gametes look the same. In contrast, multicellular organisms, including Volvox, produce eggs and sperm-they are distinctly male and female. Yet no one really has any idea how the evolution of males and females occurs or what genetic changes were required to achieve it," explains Umen.

Although the genomes of Chlamydomonas and Volvox are similar in most ways, there is one glaring exception that provided the Salk researchers with an entrée into the origin of male and female sexes-the so-called mating locus that functions in much the same way as human X and Y chromosomes to determine gender.

When Umen and his colleagues examined the mating locus genes in Chlamydomonas and Volvox they found that they shared some of the same genes, as you would expect from closely related species. However, Volvox also now possessed a surprising variety of new genes that were added to its expanded mating locus, and expression of many of these genes had come under the control of the male or female differentiation programs.

"We found that the Volvox mating locus is about five times bigger than that of Chlamydomonas," says postdoctoral researcher and co-first author Patrick Ferris, Ph.D. "We wanted to understand the evolutionary basis of this. How did it happen? And where did these new genes come from?"

To trace the origin of the added genes, the team looked to see if they could also find them in Chlamydomonas. "We found that although some of the mating locus genes in Volvox are completely new, many of them have counterparts in Chlamydomonas that are near the mating locus," explains co-first author Bradley Olson, Ph.D. "So Volvox has taken these genes that initially had nothing to do with sex, incorporated them into its mating locus, and started using some of them in its sexual reproductive cycle."

The team is now studying these new mating locus genes to understand their individual roles in sex determination and sexual development.

They have already identified a Volvox mating locus gene named MAT3 that appears to have evolved a new role in sexual differentiation. MAT3 is related to a human gene called the retinoblastoma tumor suppressor that controls cell division and is frequently mutated in cancer cells. In Volvox, MAT3 probably has a role in controlling cell division as it does in animals and plants, but has also acquired intriguing gender-specific differences in its sequence and expression pattern that correlate with differences in male/female reproductive development. Umen's laboratory is following up on this finding to determine the newly evolved role of MAT3 in Volvox gender specification.

"This study shows that Volvox and its relatives are a powerful model in which to study the evolution of sex," says Umen. "It provides us with a system in which we can retrace evolutionary history to ask questions about the origin of gender and other traits that are difficult to approach in groups such as plants and animals."

The team is also working with collaborators to examine the mating locus of an evolutionary intermediate between Chlamydomonas and Volvox called Gonium,which has between four and 16 cells. "Gonium allows us to look at the evolutionary steps between Chlamydomonas and Volvox to better understand how the evolutionary process happened," says Ferris.

In addition to Ferris, Olson and Umen, contributors to this work were Peter L. De Hoff, Ph.D., and Sa Geng, Ph.D. at the Salk Institute; Stephen Douglass, David Casero and Matteo Pellegrini at UCLA; Simon Prochnik at the U.S. Department of Energy (DOE) Joint Genome Institute (JGI), Rhitu Rai at the Salk Institute and the Indian Agricultural Research Institute, New Delhi; Jane Grimwood and Jeremy Schmutz at Hudson Alpha Institute for Biotechnology, Alabama; Ichiro Nishii at Nara Women's University, Nara, Japan; and Takashi Hamaji and Hisayoshi Nozaki at the University of Tokyo, Japan.

Patrick Ferris, Bradley J. S. C. Olson, Peter L. De Hoff, Stephen Douglass, David Casero, Simon Prochnik, Sa Geng, Rhitu Rai, Jane Grimwood, Jeremy Schmutz, Ichiro Nishii, Takashi Hamaji, Hisayoshi Nozaki, Matteo Pellegrini, and James G. Umen. Evolution of an Expanded Sex-Determining Locus in Volvox. Science, 16 April 2010 328: 351-354 DOI: 10.1126/science.1186222

Fish bounty hope after Aila churns bay

Cyclone Aila, which left a trail of death and destruction in Bengal in May last year, may lead to a boost in fish catch in eastern India over the next few months, a top ocean scientist said today.

Shailesh Nayak, secretary with the ministry of earth sciences, told a gathering at the 97th Indian Science Congress that the cyclone which killed nearly 140 people and affected 65 lakh in Bengal, caused an unprecedented spurt in the production of a marine organism which forms the bottom of the aquatic food chain.

"Following the cyclone, the production of phytoplankton (microscopic plant-like marine organisms) doubled in the Bay of Bengal," Nayak said. This bloom that lasted a month was spread over an area of 3,000sqkm in the Bay of Bengal, he said.

While such algal blooms are commonly observed in India's western coast, it rarely happens in the Bay of Bengal because its waters are highly compartmentalised. As a result, there is a limited scope for the circulation of the nutrient-rich water from the bottom to the surface and vice versa.

The algal bloom may have beneficial effects on fish catch from the sea, fishery experts said. "Fish availability increases considerably after a phytoplankton boom," said B. Madhusoodana Kurup, the director of the school of industrial fisheries at the Cochin University of Science and Technology in Kerala. This is because phytoplankton are eaten by another set of marine organisms called zooplankton which forms the feed for fish. When zooplankton are abundant in the spawning season, fish production goes up, Kurup said.

Such a spurt in potential fish production is normally witnessed six months to 18 months after the phytoplankton boom, depending on the type of fish harvested from a particular area. Considering that some of the prominent marine fish varieties harvested in Bengal are perch, mackerel and carangid, the effective increase in yield can be expected one year to 18 months after the disaster, he said.

Nayak said a passing cyclone triggers a churning process in the ocean, which in turn brings up the nutrients lying at the bottom of the sea surface. The increase in nutrient availability prompts the plankton to work overtime to produce more.

Mapping Nutrient Distributions Over The Atlantic Ocean

Large-scale distributions of two important nutrient pools -- dissolved organic nitrogen and dissolved organic phosphorus (DON and DOP) have been systematically mapped for the first time over the Atlantic Ocean in a study led by Dr Sinhue Torres-Valdes of the National Oceanography Centre, Southampton. The findings have important implications for understanding nitrogen and phosphorus biogeochemical cycles and the biological carbon pump in the Atlantic Ocean.

Tiny marine plants called phytoplankton living in the sunlit surface waters of the oceans produce organic matter through the process of photosynthesis, thereby drawing carbon dioxide down from the atmosphere. Much of this organic matter is recycled, but some of it -- the so-called export production -- sinks as 'marine snow' to the deep ocean. This is also known as the biological carbon pump, and it helps to significantly reduce the CO2 released by the burning of fossil fuels (oil, gas and coal), that would otherwise accumulate in the atmosphere.
In addition to light, phytoplankton growth requires nutrients for growth. However, inorganic nutrients are in short supply in vast areas of the oceans known as oligotrophic regions or oligotrophic oceans. This means that phytoplankton must get the nutrients from somewhere else and therefore "understanding the sources and distribution of nutrients is of major interest to oceanographers," says Torres-Valdes. The new study involved scientists based at the National Oceanography Centre, Southampton and the University of Liverpool.
The scientists studied the distributions of dissolved organic nutrients during eight research cruises in the Atlantic between spring 2000 and autumn 2005. Six of these cruises sampled north-south transects between 50 degrees N and 50 degrees S, while the other two sampled east-west transects at 24 and 36 degrees N. In this way, they were able systematically to cover large tracts of the Atlantic Ocean.
"This big effort combines observations and a modelling study in order to understand the role dissolved organic nutrients play in export production" said Torres-Valdes: "The large scale distributions revealed very interesting things: First, nutrient pools in surface waters are dominated by dissolved organic nutrients, making up typically more that 75% of the total nutrient pools in the upper 100 metres of the oligotrophic Atlantic Ocean. Second, patterns emerged showing differences exist between the extensive oligotrophic North and South Atlantic subtropical gyres. DON and DOP concentrations are lower in the North Atlantic. These differences are more striking in the case of DOP, which is very low in the North Atlantic subtropical gyre."
This is important because export production over the nutrient poor, or 'oligotrophic' subtropical gyres is thought to account for up to half of global oceanic carbon export. The patterns observed probably reflect differences in how dissolved organic nutrients are recycled, with DON being mostly refractory. DOP seems more easily taken up by organisms than DON. In the North Atlantic subtropical gyre, DOP may actually provide the extra phosphorus required by microbes that 'fix' nitrogen.
The researchers also used a computer model to study the effect of cycling and transport on export production. The modelling work shows that both DON and DOP are important. While DON contributes up to 40% of the particulate nitrogen export, DOP contributes up to 70% of the modelled particulate phosphorus export. This also shows that DOP is more easily used by microbes than DON.
The observations and model results are consistent with the hypothesis that DON and DOP are important for sustaining export production in surface layers of oligotrophic gyres. Specifically, these dissolved organic nutrients are produced as a result of enhanced primary production over upwelling regions -- the tropical Atlantic more or less along the equator, off the Northwest African Coast and the North Atlantic subpolar gyre. These nutrients are then distributed by the ocean circulation, with a very important eddy component, and are then used and recycled as they are transported.
"It's very likely that this situation also applies to many nutrient-poor marine systems, including other subtropical gyres, the Mediterranean Sea, and summer, stratified shelf seas," said Torres-Valdes.
The study was supported by the UK Natural Environment Research Council.
The researchers are Sinhue Torres-Valdes NOCS), V. Roussenov (University of Liverpool), Richard Sanders (NOCS), S. Reynolds, S. (U. Liverpool; now at the British Oceanographic Data Centre, Liverpool, X. Pan (NOCS; now at the British Oceanographic Data Centre), R. Mather U. (Liverpool), A. Landolfi (NOCS; now at Leibniz-Institut Fur Meereswissenschaften, Marine), G. Wolff (U. Liverpool), Eric Achterberg (NOCS) and R. G. Williams (U. of Liverpool).

Adapted from materials provided by National Oceanography Centre, Southampton (UK), via EurekAlert!, a service of AAAS.

How Dinoflagellates Protect Themselves During Photosynthesis

During photosynthesis at high light intensities dangerous oxygen radicals can form inside cells. Dinoflagellates have a unique light-harvesting complex (antenna) which can divert superfluous energy extremely efficiently to avoid this cell damage. In cooperation with colleagues in the USA and the Czech Republic, a team of biophysicists from the Ruhr-University Bochum around Prof. Eckhard Hofmann and Tim Schulte has now been able to determine which molecules in the antenna are of significance.

In the complex four carotenoid molecules cluster around a central chlorophyll molecule. The researchers were able to identify one specific carotenoid as a type of integrated lightning rod. It interacts with a “short-living” (nanosecond range, one millionth of a millisecond), energetically activated state of the chlorophyll and diverts the superfluous energy as soon as the chlorophyll passes into a “long-living” (microsecond range, a thousandth of a millisecond) energy state dangerous for the cell.
The scientists have published their findings in the current edition of the Proceedings of the National Academy of Science (PNAS).
During photosynthesis, plants and algae use biophysical and biochemical processes to convert light-energy into chemically stable forms of energy storage. Pigments bound in protein complexes are essential for light-harvesting.
Different pigments absorb different wavelengths of the natural light spectrum, leading to the different colours visible to the human eye.
Plants primarily use green chlorophyll for light absorption, but also contain carotinoids (yellow, orange or red) responsible for the wide spectrum of colouring of autumn foliage, or fruits such as the red tomato. In plants, carotinoids cannot only harvest light, but are also capable of quenching of superfluous light-energy that cannot be used during photosynthesis. They thus primarily have a protective function, preventing the organism from building toxic oxygen radicals when solar radiation is too high.
Dinoflagellates use the carotinoid peridinin as light-harvesting pigment
Dinoflagellates are an important part of marine plankton and live at a depth of about ten metres below sea level. A special attribute of dinoflagellates is that they use a carotinoid, namely peridinin, as light-harvesting pigment. These algae make use of the fact that peridinin absorbs light of exactly the wavelength that predominates at this specific level below the surface of the sea. The dinoflagellates produce a unique light-harvesting complex, the peridinin-chlorophyll-protein (PCP) for this purpose. This complex consists of one chlorophyll molecule per four peridinin molecules. The peridinins harvest the incoming light and transfer the energy extremely efficiently onto the internal chlorophyll molecule. Presumably the energy is then transferred from this chlorophyll molecule to other light-harvesting proteins and ultimately to the central photosystems where energy transformation and oxygen production take place.
Carotinoid notices excited state of chlorophyll
By targeted modification of the peridinin-chlorophyll-protein, scientists in Bochum -- working at an international level -- have now managed to identify a single peridinin molecule within the peridinin quartet, which interacts more strongly with the central chlorophyll. This peridinin molecule is located so close to the chlorophyll that it is aware of its excited energy state. This proximity also appears to be the prerequisite for preventing the development of a long-living excited state of the chlorophyll. The formation of such a long-living so-called triplet state leads to the development of toxic oxygen radicals that damage the cells.
International cooperation to clarify the relationship between the structure and function
The structural biological research performed in Bochum had to be combined with femtosecond (10 to the power ‑5 seconds) resolution absorption spectroscopy to be able to investigate this carotinoid-chlorophyll interaction. This was done in Connecticut, USA. Eckhard Hofmann praised this project as an outstanding example of international interdisciplinary cooperation. Based on the results of preparatory research work performed by Roger Hiller and his team from Australia, the biophysicists in Bochum were able to analyze the structure of the proteins investigated. The ultrafast spectroscopic measurements were carried out in extremely close cooperation with Harry Frank and Dariusz Niedzwiedzki's research team in Connecticut. The results were interpreted with the support of Robert Birge (Connecticut) and Tomás Polivka (University of South Bohemia, Czech Republic).
Biophysics and Protein Research Department
The infrastructure for the protein crystallography used in this project was developed by Prof. Eckhard Hofmann during the past few years, originally within the frameworks of the Protein Centre and currently in the Protein Research Department (Contact: Prof. Klaus Gerwert) which is part of the Department of Biophysics, Faculty of Biology and Biotechnology. The work is funded within the collaborative research center SFB480 "Molecular Biology of complex functions in botanical systems" (Contact: Prof. Ulrich Kück). Adapted from materials provided by Ruhr-Universitaet-Bochum, via AlphaGalileo.

Could Tiny Diatoms Help Offset Global Warming?

Diatoms -- some of which are so tiny that 30 can fit across the width of a human hair -- are so numerous that they are among the key organisms taking the greenhouse gas carbon dioxide out of the Earth's atmosphere.

The shells of diatoms are so heavy that when they die in the oceans they typically sink to watery graves on the seafloor, taking carbon out of the surface waters and locking it into sediments below.
Scientists have reported the discovery of whole subsets of genes and proteins that govern how one species of diatom builds its shell. For oceanographers, the work might one day help them understand how thousands of different kinds of diatoms -- and their ability to remove carbon dioxide from the atmosphere -- might be affected by something like global climate change. Material scientists involved in the work are interested in the possibilities of manipulating the genes responsible for silica production as a way of fabricating more efficient computer chips.
Diatoms, most of which are far too tiny to see without magnification, are incredibly important in the global carbon cycle, says Thomas Mock, a University of Washington postdoctoral researcher in oceanography and lead author of the paper. During photosynthesis, diatoms turn carbon dioxide into organic carbon and, in the process, generate oxygen. They are responsible for 40 percent of the organic carbon produced in the world's oceans each year.
The new work took advantage of the genomic map of the diatom Thalassiosira pseudonana published in 2004 by a team led by UW oceanography professor Virginia Armbrust, who is corresponding author of the new PNAS paper.* Thalassiosira pseudonana is encased in a hatbox-shaped shell comprised of a rigid cell wall, made mainly of silica and delicately marked with pores in patterns distinctive enough for scientists to tell it from other diatoms.
Armed with the genomic map, the researchers changed environmental conditions in laboratory cultures of Thalassiosira pseudonana, for example limiting the amount of silicon and changing the temperatures. Then researchers used what's called "whole genome expression profiling" to determine which parts of the genome were triggered to compensate.
Think of a plant on a windowsill that starts getting a lot more sunlight, Mock says. The new set of conditions will cause genes in the plant to turn on and off to help the plant acclimate to the increased light as best it can.
Scientists since the late 1990s have found only a handful of genes that influence diatom shell formation. The work with Thalassiosira pseudonana identified large, previously unknown subsets. A set of 75 genes, for example, was triggered to compensate when silicon was limited.
The researchers were surprised to find another subset of 84 genes triggered when either silicon or iron were limited, suggesting that these two pathways were somehow linked. Under low-iron conditions, the diatoms grew more slowly and genes involved in the production of the silica shell were triggered. Individual diatoms also tended to clump together under those conditions, making them even heavier and more likely to sink.
The response of thin and thick cell walls depending on the amount of iron available had been observed at sea but "no one had a clue about the molecular basis," Mock says.
Considering that 30 percent of the world's oceans are iron-poor, some scientists have suggested fertilizing such areas with iron so diatoms become more numerous and absorb more carbon dioxide from the atmosphere, thus putting the brakes on global warming. If, however, adding iron causes diatoms to change the thickness of their shells then perhaps they won't be as likely to sink and instead would remain in the upper ocean where the carbon they contain might be released back to the atmosphere as they decay or are eaten.
"Iron increases primary production by diatoms but our study adds another concern about the efficiency of iron fertilization," Mock says.
Along with helping scientists understand implications for climate change and absorption of carbon dioxide, diatoms can manipulate silica in ways that engineers can only dream about.
University of Wisconsin professor Michael Sussman, the co-corresponding author on the paper, says the new findings will help his group start manipulating the genes responsible for silica production and potentially harness them to produce lines on computer chips. This could vastly increase chip speed because diatoms are capable of producing lines much smaller than current technology allows, he says.
*This research was published recently in the online edition of the Proceedings of the National Academy of Sciences.
Other co-authors from the University of Washington are Vaughn Iverson, Chris Berthiaume, Karie Holtermann and Colleen Durkin; from Systemix Institute is Manoj Pratim Samanta; and from University of Wisconsin are Matthew Robinson, Sandra Splinter BonDurant, Kathryn Richmond, Matthew Rodesch, Toivo Kallas, Edward Huttlin and Franceso Cerrina.
Funding for the research came from the Gordon and Betty Moore Foundation, National Science Foundation, German Academic Exchange Service, National Institutes of Health Genomic Sciences Training Center and the University of Wisconsin. Adapted from materials provided by University of Washington

'Milking' Microscopic Algae Could Yield Massive Amounts Of Oil

Scientists in Canada and India are proposing a surprising new solution to the global energy crisis —"milking" oil from the tiny, single-cell algae known as diatoms, renowned for their intricate, beautifully sculpted shells that resemble fine lacework.

Richard Gordon, T. V. Ramachandra, Durga Madhab Mahapatra, and Karthick Band note that some geologists believe that much of the world's crude oil originated in diatoms, which produce an oily substance in their bodies. Barely one-third of a strand of hair in diameter, diatoms flourish in enormous numbers in oceans and other water sources. They die, drift to the seafloor, and deposit their shells and oil into the sediments. Estimates suggest that live diatoms could make 10−200 times as much oil per acre of cultivated area compared to oil seeds, Gordon says.
"We propose ways of harvesting oil from diatoms, using biochemical engineering and also a new solar panel approach that utilizes genetically modifiable aspects of diatom biology, offering the prospect of "milking" diatoms for sustainable energy by altering them to actively secrete oil products," the scientists say. "Secretion by and milking of diatoms may provide a way around the puzzle of how to make algae that both grow quickly and have a very high oil content."

Adapted from materials provided by American Chemical Society. Ramachandra et al. Milking Diatoms for Sustainable Energy: Biochemical Engineering versus Gasoline-Secreting Diatom Solar Panels. Industrial & Engineering Chemistry Research, 2009; 090609115002039 DOI: 10.1021/ie900044j

When Glass Develops Into a Shell: New Findings in Diatoms

Diatoms are microalgae that are responsible for nearly a quarter of the oxygen we breathe, but how does their glass-like skeleton develop? Researchers from CNRS and ENS Paris have solved part of the mystery concerning these organisms, so abundant in our oceans, by discovering several genes that are involved in the storage and transport of silica, the principal constituent of glass.

Published in the journal PLoS One, their study suggests a reorganization of certain genes that optimizes their response in the presence of silica. Above all, they confirm the important silicon requirements of diatoms. Elucidation of these mechanisms will enable a clearer understanding of glass chemistry and the anticipation of certain environmental modifications linked to the silicon and carbon cycles.
Silicon, the most abundant element on Earth after oxygen, has long been used by architecture and industry, notably as a component in glass (in the form of silica). This substance is essential to the growth of certain species of microalgae called diatoms. These astonishingly diverse, microscopic algae prosper in most of the oceans, rivers and lakes of the world. Endowed with a glass-like shell, they are one of the most abundant types of phytoplankton and are of considerable interest to scientists because of their numerous applications (as a model in the field of nanotechnologies , for their role in climate regulation , etc.).
A team of scientists led by Pascal Jean Lopez from CNRS has tried to understand the mechanisms that control the formation of their glass-like extracellular skeleton. Indeed, the processes involved in their assimilation, storage and transport of silicon have so far remained poorly understood. Clarification of these factors would improve our overall understanding of diatoms. And the stakes are high: these algae produce nearly a quarter of the oxygen we breathe, which is almost as much as tropical forests.
This study focused on one of the rare diatom species in which the synthesis of a silicon skeleton is not obligatory, called Phaeodactylum tricornutum. The scientists thus revealed that even if this particular species can survive without silicon, it still seeks to assimilate it. Above all, they discovered that a grouping of certain genes must have been favored during its evolution. This spatial rearrangement enabled a better coordination of the genome response in the presence of silicic acid (the dissolved form of silicon). The scientists also managed to identify genes likely to be implicated in the storage and metabolism of this compound, as well as demonstrating certain types of gene regulation responsible for silicon transport, both at the level of their expression and their cellular localization.
"Elucidation at the molecular level of silicon biomineralization is essential if we are to predict the effects of anthropogenic environmental changes on the biogeochemical cycle of silicon," explained Lopez. Adapted from materials provided by CNRS (Délégation Paris Michel-Ange), via AlphaGalileo.

Nitrogen Fixation And Phytoplankton Blooms In The Southwest Indian Ocean

Observations made by Southampton scientists help understand the massive blooms of microscopic marine algae – phytoplankton – in the seas around Madagascar and its effect on the biogeochemistry of the southwest Indian Ocean.

The observations were made by researchers based at the National Oceanography Centre, Southampton (NOCS) during a 2005 hydrographic survey south and east of Madagascar while aboard the royal research ship RRS Discovery. The fully analysed results are published in the journal Geophysical Research Letters.
Nitrogen-fixing bacteria convert atmospheric nitrogen into nitrogen compounds that organisms can then use as food. This process is thought to be important in areas of the ocean where nitrogen-based nutrients are otherwise in short supply, and the researchers confirm that this is indeed the case in the region south of Madagascar.
But there were some surprises. Previously, it has been thought that the large-scale autumn bloom that develops in this region is driven by nitrogen-fixing blue-green algae, or cyanobacteria, called Trichodesmium, colonies of which the researchers found to be abundant. However, the 2005 bloom was dominated by a diatom – a type of phytoplankton – the cells of which play host to another nitrogen-fixing cyanobacterium called Richella intracellularis, with Trichodesmium apparently playing second fiddle.
Diatoms have relatively large cells, and when they die they sink down the water column, carrying with them carbon that is ultimately derived from carbon dioxide drawn from the atmosphere though the process of photosynthesis. "Carbon dioxide is a greenhouse gas, and enhanced export of carbon to the deep ocean in the bodies of diatoms is an important natural mechanism by which the ocean regulates atmospheric carbon dioxide and our climate," says team member Dr Alex Poulton of NOCS.
The researchers believe that their findings will have an impact on modelling and satellite studies of the Madagascar bloom. "Future research will also need to account for the magnitude of carbon export associated with diatoms and their nitrogen-fixing guests in the southwest Indian Ocean, and indeed other subtropical oceanic settings," says Dr Poulton.
Journal reference:
Poulton, A.J., Stinchcombe, M.C. & Quartly, G.D. High numbers of Trichodesmium and diazotrophic diatoms in the southwest Indian Ocean. Geophysical Research Letters, 2009; 36 (15): L15610 DOI: 10.1029/2009GL039719
Adapted from materials provided by National Oceanography Centre, Southampton (UK).

'Toxic' seaweed spreading on France's northern coast

Mounds of putrified green algae are building up on France's northern coast, releasing poisonous fumes blamed for the recent death of a horse and the collapse of the rider.Part of the coastline has been declared off-limits as local authorities acknowledge they are unable to get rid of the decomposing seaweed that has washed up on shores in more than 80 communities across Brittany.Green groups accuse President Nicolas Sarkozy's government of turning a blind eye to an "environmental cancer" caused by the algae and blame intensive farming for producing nitrates that feed the seaweed's toxicity.Veterinarian Vincent Petit lost consciousness and his horse collapsed when he slipped on a patch of rotting algae near the beach of Saint-Michel-en-Greve on July 28.The horse died almost instantly and Petit was pulled to safety by a crew of workers who happened to be nearby.The veterinarian has since threatened to sue local authorities for reckless endangerment, raising alarm in a string of coastal communities in Brittany's Cote d'Armor region."The death of the horse may be the opportunity to get things moving so that finally, something is done," said Rene Ropartz, mayor of Saint-Michel-en-Greve.Some 400 people turned out Sunday for a rally on the town's beach to demand action from the government to deal with the green algae problem once and for all.Already this year, the town of 500 souls has spent a paltry 150,000 euros (212,000 dollars) to clean up the algae and that effort is floundering over the growing masses of the nuisance."Two or three years ago, we would collect a maximum of 21,000 tonnes of algae. But this year, we are going to beat those records by a long shot," said Ropartz.Yvette Dore, mayor of the nearby town of Hillion, said clean up operations had yielded in early August the same amount of green algae usually collected by the end of October.The problem has plagued the area for more than 30 years but local leaders say more green algae has washed up this year and new territory is being invaded on the Atlantic coast.The green algae develops in shallow waters such as the wide bays in Brittany, fed by the farm chemicals seeping into the water.Environmental groups say the onus is on Brittany's farmers, mostly pig raisers, to take action to prevent nitrates from polluting the water.The group Eau et Rivieres de Bretagne on Monday accused the government of ignoring the algae problem and said shutting down beaches was not the answer."Everyone knows that only a major reduction of the use of fertilizers and other nitrogen chemicals will result in a lower green algae tide," said the group.Local doctor Pierre Philippe said fumes from the seaweed can be noxious in some cases depending on the state of putrification. His advice is to stay away from them."Up until now, it was not a major problem, other than the cleanup and the cost of those operations," said Joel Le Jeune, mayor of Tredrez-Locquemeau. "But now the safety of people and animals is at stake." Le Jeune decided to bar access to a strip of 200 metres of coastline where the green algae is thick and potent. Due to the rugged terrain, workers had been unable to clean up that area. But Dore, the mayor of Hillion, insisted that locally-elected officials were powerless to deal with what she described as an agricultural problem, saying the matter went far beyond their jurisdiction. The green algae has also been bad for business. Mario Scotto, owner of the last beach hotel in the village of Saint-Michel-en-Greve, blames the foul-smelling seaweed for the drop in tourism. "It has caused enormous damage," said Scotto.

Great Diversity Of Marine Plankton Drive Oceanic Photosynthesis

Marine biologists have demonstrated that there is considerable diversity amongst the smallest microalgae belonging to the group of so-called haptophytes(1). Scientists from the Marine Biology Laboratory in Roscoff and Oceanographic Laboratory in Villefranche sur Mer (UPMC/CNRS), in collaboration with Rutgers University (USA) and University of Ottawa (Canada), have shown that these photosynthetic microorganisms, highly diversified and extremely abundant, are some of the most important producers of oceanic organic matter.

The oceans of our planet are responsible for more than half of the global production of organic matter, due to the photosynthetic activity of marine phytoplankton. Indeed, these microorganisms suspended in water are involved in the carbon cycle by using sunlight to produce matter. As a driver of this oceanic photosynthesis, novel biodiversity has been revealed by researchers working at the marine research stations in Roscoff and Villefranche sur Mer (UPMC/CNRS).
These scientists have resolved an important oceanographic paradox: the omnipresence in seawater of a photosynthetic pigment (2) (19'-hexanoyloxyfucoxanthin) borne by an unsuspected diversity of organisms. Thanks to novel genetic protocols, they have identified a multitude of microorganisms carrying this pigment: protists belonging to the Haptophyta lineage.
Protists are unicellular, eukaryote (with a single nucleus) organisms that are dispersed throughout the biosphere. Neither bacterium, nor virus, nor plant nor animal as such, they display major anatomical and physiological plasticity. Haptophyta constitute one of the most ancient lineages of protists.
Calculations suggest that a few liters of tropical water may contain more than 1000 genetically-different species of these haptophytes, of a size ranging from 2 to 8 microns (thousandths of a millimeter). A quantitative evaluation of the global importance of their pigment during the year 2000 suggested that the biomass of these organisms may be up to twice as important as that of cyanobacteria or diatoms, the two groups of phytoplankton classically considered as the champions of photosynthesis in open ocean waters.
The success of these small haptophytes may reside in the fact that in addition to feeding from light via photosynthesis, they consume bacterial prey, organic matter or pico-protists (protists with dimensions of between 1 and 2 microns) and thus supplement their diet as they diversify.
Identifying the richness and functioning of ocean plankton biodiversity is essential to understanding how climate is regulated by living organisms.
Studies on marine protists are the subject of new research programs being coordinated by CNRS scientists in Roscoff, such as BioMarKs (Biodiversity of Marine euKaryotes) along European coastlines, or Tara-Oceans, the round-the-world scientific expedition on board the yacht Tara.
Notes: (1): Haptophytes are unicellular organisms with a flagellum-like appendix called a haptonema.
(2): A photosynthetic pigment is a colored molecule that is capable of absorbing the light radiation necessary for photosynthesis.
Journal reference:
Liu et al. Extreme diversity in noncalcifying haptophytes explains a major pigment paradox in open oceans. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0905841106
Adapted from materials provided by CNRS (Délégation Paris Michel-Ange).

A thirst for blood sparks toxic algal blooms

The blooming of toxic algae that occurs during the summer conceal a fight for life and death. Scientists at the University of Gothenburg, Sweden, propose in an article published in the journal PNAS that algal blooms are created when aggressive algae kill and injure their competitors in order to absorb the nutrients they contain.
"The behaviour of the algae can be compared to that of blood-sucking insects", says Per Jonsson of the Department of Marine Ecology.
The blooming of toxic algae in the oceans and lakes is a familiar health risk and causes problems every summer, leading to increased costs for water cleaning, water consumption and the tourist industry. Scientists still do not know why algal blooms arise, and what it is that causes certain species of microalgae to multiply and form dense blooms.
New explanation
Scientists within the research platform MARICE (Marine Chemical Ecology) at the Faculty of Science, the University of Gothenburg, present a new possible explanation of why algal blooms arise in a study published in the international journal Proceedings of the National Academy of Sciences (PNAS).
Other factors
Current theory postulates that the algae produce toxins not only in order to inhibit the growth of competing species, but also to protect themselves from predators. The strategy of inhibiting competitors, however, is difficult to explain from an evolutionary perspective. The turbulent ocean surface means, quite simply, that it is difficult for one algal species to obtain exclusive rights on the effect of a toxin that inhibits competitors. The production of the toxin must be explained by other factors.
Kills competators
Marine ecologist Per Jonsson and his colleagues suggest that the inhibition of competitors that previous research had found is only a side-effect of a considerably more aggressive behaviour: toxic algae injure or kill competing algae in order to gain access to the nutrients in their cells.
Blood-sucking
"The way the algae absorb food is similar to that of blood-sucking insects, such as mosquitoes. Our study shows that this theft of nutrients may be an important mechanism in the formation of blooms of toxic plankton", says Per Jonsson."The results will lead to several further experimental studies, and we hope that these will eventually contribute to solving the mystery of how algal blooms arise."
The article, Formation of harmful algal blooms cannot be explained by allelopathic interactions, was published in PNAS on 15 June, and was written by Per Jonsson, Henrik Pavia and Gunilla Toth, all of whom are scientists working at the Department of Marine Ecology, University of Gothenburg.

Low Summer Iron Availability Limits Biological Production In The High-latitude North Atlantic

Southampton scientists have demonstrated an unexpected role of iron in regulating biological production in the high-latitude North Atlantic. Their findings have important implications for our understanding of ocean-climate interactions.

Tiny plant-like organisms called phytoplankton dominate biological production in the sunlit surface waters of the world's oceans and, through the process of photosynthesis, sequester large amounts of atmospheric carbon dioxide. A proportion of the carbon is exported to the deep ocean, and because carbon dioxide is a greenhouse gas, this so-called 'biological carbon pump' helps prevent runaway global climate warming.
Iron is an essential micro nutrient for phytoplankton growth. In high-nutrient, low-chlorophyll (HNLC) oceanic regions, phytoplankton growth is limited by low iron availability. Classical HNLC regions, which account for about a third of the world's oceans, include the Southern Ocean and the subpolar North Pacific.
In contrast, it has been widely assumed that iron supply does not limit biological production of the high-latitude (>50 degrees N) North Atlantic Ocean. Here, winter cooling causes the sinking of nutrient-depleted surface waters and their replacement by deep nutrient-rich water. This winter 'overturning' replenishes surface water nutrients, and in the spring, when light intensities increase, a large phytoplankton bloom develops, leading to high rates of carbon export.
However, in many regions of the open North Atlantic, including the Iceland and Irminger Basins, residual amounts of nitrate persist into the summer period, after the spring bloom has ceased. This represents an inefficiency of the biological carbon pump that is potentially of global significance to the partitioning of carbon between the atmosphere and ocean.
Phytoplankton are grazed upon and some of the larger phytoplankton species such as diatoms with low grazing mortality are susceptible to silicate shortage. Traditionally, it has been believed that these factors, acting in concert, might be sufficient to terminate the spring bloom leaving some nitrate unused. However, there have been indications that phytoplankton might simply run out of iron before they are able to exploit any remaining other nutrients.
Now a team of scientists from the National Oceanography Centre, Southampton, have tested this 'iron limitation hypothesis' for the high-latitude North Atlantic Ocean. Their measurements were performed on a cruise aboard the RRS Discovery within the central Iceland Basin during the summer of 2007, and the findings are published this month in the scientific journal Global Biogeochemical Cycles.
The researchers found that the concentration of dissolved iron in surface waters was very low, as was biological production, despite the presence of residual nitrate. Experimental addition of iron to bottles containing seawater samples increased photosynthetic efficiency, chlorophyll concentrations, and growth of several types of phytoplankton, including the ubiquitous Emiliania huxleyi, a coccolithophore.
"These results, backed up by additional experiments, are extremely exciting," said team member Maria Nielsdottir: "They provide strong evidence that low iron availability limits summer biological production in the high-latitude North Atlantic. This has only previously been suspected, but helps explain why the spring phytoplankton bloom does not continue well into the summer and why residual amounts of nitrate remain unused."
The central Iceland Basin receives little iron input from continental sources or from atmospheric dust, and some iron is also lost through detrital sinking. Moreover, the new findings suggest that iron brought to the surface during winter overturning is insufficient to support maintenance of the phytoplankton bloom into the summer.
Nielsdottir, a research student at the University of Southampton's School of Ocean and Earth Science based at the National Oceanography Centre, said: "In effect, the high-latitude North Atlantic is a seasonal HNLC region, whereas classic, HNLC regions such as the Southern Ocean remain in this condition throughout the year."
The failure of the phytoplankton community to exploit residual nitrate remaining in the summer reduces the effectiveness of the biological carbon pump. "This is important," says Nielsdottir, "because the high-latitude North Atlantic is second only to the Southern Ocean in its potential to lower atmospheric carbon dioxide and un used nitrate in the surface highlight the potential for even higher CO2 drawdown, high levels of which are an important cause of global climate warming."
The work was supported by the National Oceanography Centre with a PhD to MCN, Natural Environment Research Council, Oceans2025 and the Faroese Ministry of Interior and Law. The authors are Maria Nielsdottir, C. Mark Moore, Richard Sanders, Daria Hinz and Eric Achterberg, University of Southampton's School of Ocean and Earth Science based at the National Oceanography Centre, Southampton.
Journal reference:
Nielsdóttir, M. C., C. M. Moore, R. Sanders, D. J. Hinz, and E. P. Achterberg. Iron limitation of the postbloom phytoplankton communities in the Iceland Basin. Biogeochem. Cycles, 23, GB3001 DOI: 10.1029/2008GB003410
Adapted from materials provided by National Oceanography Centre, Southampton (UK).

Fish kill feared as algae blooms in Bay

A fish kill could happen soon in Tampa Bay. Scientists in Pinellas County are concerned about an algae bloom stretching 14 miles from Safety Harbor to Weedon Island. The bloom appears as reddish-brown streaks in the water."It's an indicator that something is wrong," said Kelli Levy, with the Pinellas county Department of Environmental Management. "A bloom only occurs if we have stimulated it in some way to grow that fast and to that extent."The bloom could cause the fish kill. At night and on cloudy days, algae depletes oxygen from the water. Fish are left unable to breath."We can have very low oxygen, so you might see fish in the water gulping for air," said Levy."There's no potential human health, risk per se. It's the environmental impacts we're worried about in this case," said Cindy Heil, Senior Research Scientists at the Fish and Wildlife Research Institute.But a fish kill can prompt human health concerns. Last year, thousands of dead fish turned up floating along the Courtney Campbell Causeway. Ben T. Davis beach shut down. The current bloom is much bigger."That area is 3.8 miles where dead fish were found. So now, the bloom is all the way down to Weedon Island so that's 14 miles," said Levy.Microscopic algae can't be removed from the water. It feeds on unnecessary pollutants, from us."We had a lot of rain in May which brought in with it pollutants like fertilizers and yard waste and things that go into storm drains and then we get a good rain event and then it flushes out into the Bay," said Levy.She says the county is making improvements to better protect water quality. "We're building storm water ponds so that the runoff goes from the drain into a pond and gets cleaned a little bit and then the pond discharges to the Bay," Levy said.The algae is not Red Tide. It's Pyrodinium, a species potentially toxic to Shellfish and definitely suffocating to all fish.Levy says a fish could happen in the "near future." However, Heil told FOX 13 "We don't expect one, but if we get a period of more than one or two cloudy days, it's something well be keeping an eye out for.". Kristin Wright Fox News

Saharan Dust Storms Linked To Enigmatic Fertilizer Plankton In Ocean

The tropical Atlantic waters around Cape Verde are very low in plant nutrients. Nitrogen is in especially short supply and limits the growth of the phytoplankton, the tiny plants that are at the basis of the food chain in the ocean. In this area, the nutrients fall out from the sky: Trade winds carry Saharan dust rich in iron and phosphorus which can fertilize the surface of the ocean. This was one of the reasons for the IFM-GEOMAR and other German and UK institutions to establish an observatory on the Cape Verde island Sao Vicente. The Tenatso Observatory now supports long-term measurements of dust and greenhouse gases as well as an oceanographic mooring and regular sampling expeditions by the small Cape Verdean research vessel Islandia. "We're testing whether Saharan dust can promote the growth of a particular type of microbe, a cyanobacteria. These cyanobacteria can fertilize the surface of the ocean by fixing the abundant nitrogen gas that is dissolved in seawater", says Prof. Julie LaRoche from IFM-GEOMAR, co-leader of the expedition.There is plenty of nitrogen gas in the atmosphere but it needs to be "fixed" so that it turns into a fertilizer which is available to phytoplankton. The enigmatic cyanobacteria UCYN-A seems to be a very special nitrogen fixer. In contrast to other cyanobacteria, it is probably incapable of producing oxygen. This in turns enables it to fix nitrogen during the day while others cannot. The Trade Winds and frequent dust storms that make this area so important for ocean research also complicate the scientists' work. Dust samples are collected with filters on top of the atmospheric observatory. The collection of the water samples, however, requires sailing on the Islandia for several hours to the ocean observatory located 130 kilometres offshore in a surrounding water depth of 3600 metres. The samples are returned to laboratories that have been established at Cape Verde's "National Institute for Fishery Development" where the dust experiments are conducted."The working conditions are difficult and some trips on the Islandia are like a roller coaster. But overall it's a very positive work experience, thanks to our supportive Cape Verdean colleagues, the crew of the Islandia, and the general ambience on the islands ", says Stefanie Sudhaus , Ph.D. student at IFM-GEOMAR and member of the last expedition. Loaded with plenty of data from their experiments and confident that the experiments will deliver new discoveries, the scientists have returned to Kiel. During the expedition they were accompanied by scientists from the Max Planck Institute for Marine Microbiology, the Alfred Wegener Institute for Polar and Marine Research, Leibniz Institute for Baltic Sea Research and the Leibniz Institute for Tropospheric Research.Research Project at the Cape VerdeScientists from German and Cape Verdean institutes have started collecting data at Cape Verde Observatory Tenatso in 2008, measurements that they hope to continue in order to follow the effect of global change in the tropical Atlantic Ocean. Their research is part of the SOPRAN project (Surface Ocean Processes in the Anthropocene) that is largely supported by the German Federal Ministry of Education and Research (BMBF).Nitrogen fixers and UCYN-AThere is plenty of nitrogen gas (N2) in the atmosphere but only few organisms are able to "fix" it so that it turns into a fertilizer with biologically useful molecules. Cyanobacteria or blue-green algae are amongst the most important nitrogen-fixers. Until recently scientists thought that single-cell organisms could only fix the nitrogen during the night because during the day, oxygen is released through photosynthesis and inhibits nitrogen fixation by poisoning the enzyme responsible for it. The cyanobacterium UCYN-A doesn't seem to work like that. It lacks the genes for photosystem II that are needed for the oxygen release and apparently cannot fix carbon dioxide into sugars. Thus, it may utilize light energy in other ways and forgoes photosynthesis, as is normally carried out by land plants and other algae. Although this organism has never been isolated in pure culture, an initial characterization of its genome was published in 2008 by the group of Jonathan Zehr at University of Santa Cruz (Zehr et al. 2008, Science Vol. 322 no. 5904, pp. 1110-1112).

Satellite Detects Red Glow To Map Global Ocean Plant Health

Researchers from Oregon State University, NASA and other organizations said today that they have succeeded for the first time in measuring the physiology of marine phytoplankton through satellite measurements of its fluorescence – an accomplishment that had been elusive for years.With this new tool and the continued use of the MODIS Aqua satellite, scientists will now be able to gain a reasonably accurate picture of the ocean's health and productivity about every week, all over the planet.Data such as this will be critically important in evaluating the effect on oceans of global warming, climate change, desertification and other changes, the researchers said. It will also be a key to determining which areas of the ocean are limited in their productivity by iron deficiency – as this study just showed the Indian Ocean was."Until now we've really struggled to make this technology work and give us the information we need," said Michael Behrenfeld, an OSU professor of botany. "The fluorescence measurements allow us to see from outer space the faint red glow of tiny marine plants, all over the world, and tell whether or not they are healthy. That's pretty cool."Ocean phytoplankton are single-celled organisms that are responsible for half of the photosynthetic productivity on Earth. They fuel nearly all marine ocean ecosystems and are the base of the marine food chain.Measurements of phytoplankton are an important way to understand the broader health and productivity of the ocean, researchers say. Some of the measurements available prior to this, such as phytoplankton biomass or their carbon-to-chlorophyll ratio, provided part of the picture, but were often only available for tiny portions of the ocean at a time.To grow, however, these phytoplankton absorb energy from the sun, and then allow some of that energy to escape as red light that is called fluorescence. The new measurements of fluorescence, literally the dim glow that these plants put off, will help complete the understanding of ocean health on a much broader and more frequent basis.Some surprises are already in.It was known, for instance, that parts of the equatorial Pacific Ocean, some regions around Antarctica and parts of the sub-Artic Pacific Ocean below Alaska were limited in production by the poor availability of iron. The newest data, however, show that parts of the northern Indian Ocean during the summer are also iron limited – a phenomenon that had been suggested by some ocean and climate models, but never before confirmed."Iron is often brought to the oceans by dust coming off terrestrial regions, and is a necessary nutrient that often limits the potential for marine phytoplankton growth," said Allen Milligan, an OSU assistant professor of botany and co-author of this study, which is being published in the journal Biogeosciences."If forces such as global warming, circulation changes or the growth of deserts change the amount of dust entering the oceans, it will have an impact on marine productivity," Milligan said. "Now we'll be able to track those changes, some of which are seasonal and some of which may happen over much longer periods of time. And we'll also be able to better assess and improve the climate models that have to consider these phenomena."Funding for this research was provided by the Ocean Biology and Biogeochemistry Program of NASA, which announced the findings in a news conference. Other collaborators were from the University of Maine/Orono, University of California/Santa Barbara, University of Southern Mississippi, the NASA Goddard Space Flight Center, Woods Hole Oceanographic Institution, Cornell University, and the University of California/Irvine.In continued studies, researchers at OSU hope to reproduce the marine environment that these phytoplankton cells live in, learn more about their basic biology and better understand why and how they can be seen from space. Further research may also explore how the oceans might respond to iron enrichment.Journal reference:Behrenfeld et al. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton. Biogeosciences, 2009; Oregon State University

New Red Alga Discovered In Mediterranean Sea

An international team of researchers led by the University of Girona (UoG) has described a new species of red algae (Leptofauchea coralligena) in the western Mediterranean. This is the only species of the Leptofauchea genus currently known to be in the Mediterranean."The species that we have described, Leptofauchea coralligena, is a deep water red alga which can often be found in the western Mediterranean between the end of winter and autumn. It is of great ecological importance, given that it is a species characteristic of the coral lining situated between 30 and 45 metres below the surface", explains Conxi Rodríguez-Prieto, main author of the study and director of the UoG's Marine Benthic Algae team.The study of the red algae is mainly based on the morphology of the female reproductive structure and on the post-fertilisation stages. Rodríguez-Prieto affirms that "many macroalgae species were described based on sterile specimens, leading to many being classified in the wrong taxonomic groups (order, family, genus, species, and even class)".This is what happened with Leptofauchea coralligena, which, "despite being a very common species, until now was thought to belong to the Rhodymenia genus, and specifically to the Rhodymenia ardissonei species", clarifies the researcher.However, "the authentic Rhodymenia ardissonei is a common but sparse species which lives close to the surface and reproduces in a different manner (which is why it belongs even to a different family)", points out the scientist. The description of Leptofauchea coralligena, a new species for science, was possible thanks to the fact that researchers found fertile specimens and could study their reproduction.The study, recently published in the European Journal of Phycology, included the collaboration of Olivier De Clerck, a researcher from the University of Ghent (Belgium) and phycologist who is "very well-known internationally and someone with whom we have collaborated for years", adds Rodríguez-Prieto. DNA sequencing was used to confirm that the new species belongs to the Leptofauchea genus.Getting to know marine biodiversityThe Mediterranean has a great diversity of algae, but they are little known due to being so difficult to collect; they grow all the way from the surface down to 110 metres in depth. According to Rodríguez-Prieto, "the study of marine macroalgae is notably delayed in comparison to that of land plants", because individual diving did not begin until the mid 20th century.The scientific community considers the "conservation of biodiversity" fundamental , and it is therefore necessary to know which species currently exist and what their physiological requirements are.The UoG team, specialised in the reproduction, ecophysiology and ecology of red algae, especially those in deep water, is currently carrying out diverse studies on the effects of climate change. The scientists hope to "determine if the warming of the Mediterranean may affect the development and growth of various macroalgae species, among them the Leptofauchea coralligena", says Rodríguez-Prieto.Journal reference:Rodriguez-Prieto et al. Leptofauchea coralligena (Faucheaceae, Rhodophyta), a new species from the Mediterranean Sea. European Journal of Phycology, 2009; 44 (1): 107 DOI: 10.1080/09670260802357111Plataforma SINC

Origin of giant bloom discovered

A "green tide" swamped the shores of Qingdao in June 2008Scientists have discovered the source of the gigantic green tide of algae that almost derailed the Beijing Olympics sailing regatta. The huge algal bloom was triggered by a rapid expansion of farmed seaweed almost 200km down the coast, satellite images reveal. The green tide then grew and grew as it moved closer to the regatta city of Qingdao. At one point, it became the largest ever recorded anywhere in the world. Initially, the international media and many scientists suggested that excess nutrients (eutrophication) in coastal waters caused the algal bloom.We suspect that the reason the bloom had not occurred previously was that the growth of aquaculture in this region has been so rapid Dr John Keesing, CSIRO The new finding, published in Marine Pollution Bulletin, disproves that idea and suggests that similar tides could happen again. In late June 2008, the waters and shores at the Qingdao venue hosting the Olympic sailing regatta experienced a massive green tide covering about 600 sq km. Lasting over two weeks, it took more than 10,000 people to clean up, removing over one million tonnes of algae from the beach and coast. The algae responsible is called Enteromorpha prolifera .Satellites saw the algae appearing off Yancheng and moving north"It's not a dominant or common species in the local area," says Dongyan Liu, a marine biologist at the Chinese Academy of Sciences in Yantai, Shandong. "The rapid appearance and sheer scale made us suspect it had accumulated offshore and been transported in." E. prolifera pollutes aquaculture farms that grow Porphyra seaweed on semi-floating rafts made of bamboo and net curtain. The seaweed is mainly sold as food and also grown to prevent eutrophication, as the seaweed takes up nutrients that might otherwise pollute the water, allowing weeds to grow, staving other plants of oxygen. Photos passed to Liu and John Keesing of the Australian research organisation CSIRO showed the Qingdao green tide contained bamboo poles used in Porphyra aquaculture. The researchers then spoke to farmers growing the seaweed across the Yellow Sea on the coast of Jianngsu province. The timing of their harvest suggested the bloom could have originated there. To investigate further, Liu, Keesing and colleagues examined photos of China's north-eastern coast taken by instruments on board Nasa's Terra and Aqua satellites, which view the entire Earth's surface every one to two days. On the 15 May 2008, small green patches of algae, covering around 80 sq km, appeared off the coasts of Yancheng and Lianyungang in Jianngsu province, the images reveal.The bloom (in red circles) grows as it heads towards QingdaoWithin 10 days, these patches had moved away from the coast and into the Yellow Sea, covering 1,200 sq km, and impacting about 40,000 sq km of ocean, making it the largest algal boom, or green tide, ever recorded. On the 18 June, algae patches began to move towards the coast at Qingdao, landing on the shore on 28 June. Further satellite data confirmed that the right temperatures, wind speeds and oceanographic conditions existed at the time to favour the rapid growth of the algae, and transport it across the Yellow Sea. "We suspect that the reason the bloom had not occurred previously was that the growth of aquaculture in this region has been so rapid," said Keesing. >From 2003 to 2008, the coastal area used for seaweed aquaculture off the coast of Jianngsu has more than doubled to 23,000 hectares. "It has now reached a critical size where it has the capacity to produce enough Enteromorpha to cause the problems we saw in 2008," the CSIRO researcher said. To prevent a reoccurrence "we should carefully manage the distribution and production of coastal aquaculture and educate farmers not to discard unwanted Enteromorpha into the water." BBC

Researchers report 'moderately large' potential for red tide outbreak in Gulf of Maine region

Toxic bloom expected to be smaller than last year, but still significantThe potential for an outbreak of the phenomenon commonly called "red tide" is expected to be "moderately large" this spring and summer, according to researchers with the Woods Hole Oceanographic Institution (WHOI) and North Carolina State University (NCSU). This advisory is based in part on a regional seafloor survey of quantities of Alexandrium fundyense — the algae notorious for producing a toxin that accumulates in clams, mussels, and other shellfish and can cause paralytic shellfish poisoning (PSP) in humans who consume them. The survey maps are used with computer models that simulate different scenarios of weather and oceanographic conditions to indicate where and in what abundance the toxic cells might be expected in 2009. The researchers found concentrations of Alexandrium cysts — the dormant seed-like stage of the algae's life cycle — in the Gulf of Maine to be 40 percent lower than the historically high levels observed prior to last year's bloom, but still higher than the level preceding a major regional bloom in spring 2006 that closed shellfish beds from Canada to Massachusetts Bay. The Alexandrium survey has been conducted each fall since 2004 as part of several research and event response projects funded by the National Oceanic and Atmospheric Administration (NOAA) Center for Sponsored Coastal Ocean Research (CSCOR). Fall concentrations of Alexandrium cysts are one of the indicators of the magnitude of a potential bloom in spring.In October 2008, a survey team led by Don Anderson, a senior scientist in the WHOI Biology Department and the lead investigator of the Gulf of Maine Toxicity (GOMTOX) study, spent 10 days collecting seafloor sediment samples between Massachusetts Bay and the Bay of Fundy looking for Alexandrium cysts. After the samples were processed and analyzed, the team determined the cyst abundance to be about 40 percent lower than the high levels observed in fall 2007 (see figure).This is one line of evidence that leads Anderson and his colleagues to believe the bloom this spring won't be as extensive as last year's, which closed shellfish beds from the Canadian border to the Cape Cod Canal, and on the outer portions of Cape Cod as well. "Last year at this time, we issued an advisory for a very large regional bloom that did in fact occur. In hindsight, that advisory was 'easy' because the cyst concentrations were higher than we had ever seen – 30 percent higher than in 2004 just before the massive 2005 red tide that many people probably remember," said Anderson. "It's more difficult to make a prediction this year because the numbers of cysts we found are not extreme."The cysts for this year's bloom have been dormant in the seabed since late last summer, when they were formed at the end of the Alexandrium bloom. With the onset of spring and its warm temperatures and increased light, the cysts are already beginning to germinate, liberating cells that swim to the surface waters. Under the right conditions, a single cell can then divide into several hundred cells within a few weeks. But where and when the resulting bloom will make landfall depends on weather events that cannot be predicted months in advance.That's where computer modeling can help. While cyst abundance gives a general indication of the magnitude of the bloom, oceanographers Dennis McGillicuddy, a senior scientist in the WHOI Applied Ocean Physics and Engineering department, and his colleague Ruoying He of North Carolina State University (NCSU) have been working with Anderson to simulate the resulting growth and transport of the toxic cells using computer models. Working together over the last decade, the team has developed a computer simulation that incorporates weather conditions, river runoff, and various wind and current patterns to predict the intensity and location of blooms of the toxic algae in the Gulf of Maine.With data from last year's cyst counts, the WHOI and NCSU team ran their computer model through a range of scenarios, using the predominant regional wind patterns and ocean conditions from each year since 2004. (See figure......)According to He and McGillicuddy, the simulations suggest a moderately large regional bloom of Alexandrium, falling in the mid range of those that have occurred over the last five years. Red tides during those years have ranged from very large ones that stretched from the Canadian border to southern Massachusetts, including Cape Cod and the Islands, to small outbreaks that have only caused limited harvesting closures in Maine, New Hampshire, and northern Massachusetts.The researchers have found that toxicity in near-shore shellfish is the highest for years in which northeasterly storms occur, which tend to drive Alexandrium cells toward the southern New England coast. When southwesterly winds dominate, the algae tend to remain offshore. So even when there are a lot of cells in the Gulf of Maine, toxicity can be confined to offshore waters if the winds and currents cooperate.The Alexandrium cells can be expected to appear in surface waters in early April. By the end of that month, cells usually begin to appear in large numbers in the waters off coastal Maine and New Hampshire, which is when and where the first reports of toxicity typically appear. As the coastal bloom is transported to the south, the Massachusetts shoreline can be impacted as well. The severity of this year's outbreak along the coast will depend in large part on the wind patterns in May, June, and July. The GOMTOX researchers regularly share their results with coastal resource and fisheries managers in six states and at the National Oceanic and Atmospheric Administration, the Environmental Protection Agency, and the Food and Drug Administration (which oversees the safety of offshore shellfish beyond state limits). "We can only issue an advisory, as opposed to a forecast," says Anderson. "We can estimate how many cells will be in the water from the germination of cysts and potential growth of that population, but not whether those cells and that water will be blown to shore." These types of red tide or harmful algal bloom (HAB) advisories can help the economy. Advance warning of a potentially troublesome year for algae can give shellfish farmers and fishermen time to make contingency plans for the timing of their harvest or expansion of aquaculture beds; state agencies can make informed staffing decisions to accommodate additional monitoring that might be required to protect public health and the shellfish industry.The WHOI and NCSU researchers underscore that even when these major red tides occur, shellfish and other seafood products are safe to eat because they are carefully monitored. Shellfish stocks are regularly tested by state and federal agencies, ensuring that contaminated growing areas are closed to harvesting, and that dangerous product does not reach the market.

This research was supported by NOAA's Center for Sponsored Coastal Ocean Research, and the National Institutes of Health and the National Science Foundation (through the Woods Hole Center for Oceans and Human Health). Additional work examining other species of toxic algae in the Gulf and on Georges Bank is supported by the NOAA Oceans and Human Health Initiative (OHHI).The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans' role in the changing global environment.

Harmful 'red tide' hits Dubai beaches

Beaches in the Gulf tourism hub of Dubai have been plagued by a bloom of algae known as the "red tide" that has killed fish and is potentially harmful to humans, a municipality official said on Tuesday."This is a natural fauna that goes into harmful algal bloom," said Mohammed Abdulrahman Hassan, head of the marine and wildlife section in the municipality's environment office.The algae can cause skin and eye irritations as well as breathing problems for people, who should avoid swimming near it, Hassan said.The algae, whose scientific name is Cochlodinium polykrikoides, absorb oxygen at a high rate, especially at night. Reduced oxygen levels can harm fish, and the algae can also kill them by clogging their gills.On Tuesday municipality officials found algae near the iconic sail-shaped Burj Al-Arab Hotel, but Hassan said it was pointless closing sections of beach since the bloom was constantly on the move."People should use common sense. If they see the bloom or dead fish, they should not touch it and should not swim in that area," he said.Newspaper reports said the phenomenon has plagued neighbouring emirates Ras al-Khaimah and Fujairah for months, killing hundreds of tonnes of fish.One of the seven emirates comprising the United Arab Emirates, Dubai is popular with tourists and residents alike for its sunbaked beaches