Thursday, March 31, 2011

Decline in Diatoms in Great Lakes

Algal productivity in the Great Lakes, the fixation of atmospheric carbon by algae, is largely a result of the size of the springtime bloom of diatoms. Diatoms are algae that pull silica out of the water column to encase themselves in intricate glass coatings, Evans explains. "The amount of silica removed by the bloom has long been used as an indicator of algal production in the Great Lakes," she says.

Mining data on silica concentrations collected over the past 30 years, Evans and her colleagues determined that algal production was about 80% lower in 2008 than in the 1980s and 1990s. The decline began in the mid-1990s after zebra and quagga mussels invaded the lakes. The study estimates that mussels consume up to 74% of new spring algae. When the foundation of a food web is depleted, Evans says, populations of the fish at the top of the web can suffer.

Phytoplankton production is an important factor in determining both ecosystem stability and the provision of ecosystem goods and services. The expansive and economically important North American Great Lakes are subjected to multiple stressors and understanding their responses to those stresses is important for understanding system-wide ecological controls. Here we show gradual increases in spring silica concentration (an indicator of decreasing growth of the dominant diatoms) in all basins of Lakes Michigan and Huron (USA and Canadian waters) between 1983 and 2008. These changes indicate the lakes have undergone gradual oligotrophication coincident with and anticipated by nutrient management implementation. Slow declines in seasonal drawdown of silica (proxy for seasonal phytoplankton production) also occurred, until recent years, when lake-wide responses were punctuated by abrupt decreases, putting them in the range of oligotrophic Lake Superior. The timing of these dramatic production drops is coincident with expansion of populations of invasive dreissenid mussels, particularly quagga mussels, in each basin. The combined effect of nutrient mitigation and invasive species expansion demonstrates the challenges facing large-scale ecosystems and suggest the need for new management regimes for large ecosystems.

Wednesday, March 30, 2011

Melting ice reveals several winter fish kills in Iowa’s lakes, ponds

Melting ice reveals several winter fish kills in Iowa’s lakes, ponds.

The Iowa Department of Natural Resources has received numerous reports of dead fish in lakes and ponds across Iowa as the ice cover disappears for another year.

These winter fish kills have been reported at Swan Lake (Carroll), Badger Creek Lake (Madison), Clark Lake (Cerro Gordo), Kuhn Wildlife Pond (Cerro Gordo), Pilot Knob Pond (Winnebago), Alice Wyth Lake (Black Hawk), Middle Sabula and Green Island lakes (Jackson), Credit Island Lagoon (Scott), and a storm water retention pond in Guttenberg.

Fisheries staff are also watching lakes and ponds with low oxygen levels that are at risk of having a winter fish kill. Many north Iowa lakes and ponds are still under ice, so additional winter kills are likely.

Winter kills happen when a combination of ice and snow blocks sunlight from reaching aquatic plants, which in turn, stop producing oxygen. The longer the snow and ice cover lasts, the less oxygen is in the water.

“Winter kills are rarely complete kills. We get a lot of calls from farm pond owners who think they lost all of their fish in their pond to winter kill. Our advice to them is to fish the pond in the spring, note the species, number and size of what you catch and talk to their local fisheries biologist about the health of the pond,” said Joe Larscheid, chief of the fisheries bureau for the Iowa Department of Natural Resources.

“What is important to understand it that this is a natural phenomenon and has been occurring in lakes, ponds and river backwaters throughout our history,” Larscheid said. “On the positive side, winter kills create a surplus of food that allows the remaining fish to experience rapid growth over the following year or two.”

Winter kills are visible shortly after ice out when fish that died during the winter float and are blown to shore. In certain lakes, like Rathbun, Black Hawk, Storm and Coralville, these dead fish are often a source of food for channel catfish that will go on a feeding spree. Many anglers see this as an early season fishing opportunity for trophy sized channel catfish.

“Channel catfish are attracted to food that gives off a strong odor and these dead fish put off an odor that will bring in catfish from across the lake. We tell anglers to fish on the windblown shore this time of year because the dead fish will be there, followed closely by the catfish. This can be some of the best fishing of the year,” Larscheid said.

While Mother Nature may be responsible for many fish kills discovered after ice out, the Iowa DNR would like to make sure some other factor is not to blame.

“If in doubt, give your local fisheries biologist a call so we can discuss your situation,” Larscheid said.

Saturday, March 26, 2011

Red Tides Research

Red tide more harmful, study finds


Published: March 26, 2011

TAMPA - It took 22 scientists from eight organizations, more than 500 volunteers and nearly $16 million in funding, but officials now have a better grasp on the effects of red tide.

They know now that the toxin can drift as far as a mile inland, meaning that the exposure has a much wider swath than originally thought.

They found that at least 12 different toxins are contained in red tide that can be harmful to people.

They also discovered an antitoxin currently being used to develop a drug to fight cystic fibrosis.

"I think it's tremendous," Barbara Kirkpatrick, senior scientist at Mote Marine Laboratory, said of the many findings of the decadelong study.

Mote worked with the University of North Carolina Wilmington, the Centers for Disease Control and Prevention, the state Department of Health and other agencies in the most comprehensive study of red tide, the organism that blooms in the Gulf of Mexico, killing fish and fouling the air.

The drug-related discovery was one of the most exciting for Kirkpatrick. "It's just one of those awesome things that you can't predict in research," she said. "We were researching red tide and now we will help people with cystic fibrosis. That's just cool."

Researchers used to think that people visiting the beach would be OK as long as their exposure was short-lived. Now, Kirkpatrick said, they have found that someone with asthma who visits the beach for an hour during red tide can have problems for days.

They also learned that people inland as far as a mile can suffer ill-effects of red tide, she said.

"The next time we have red tide in town, our message will be a lot stronger," Kirkpatrick said. "Even mainlanders who are near the shore need to be more aware."

It's been five years since the last full-fledged outbreak of red tide.

"That's a Catch-22 when you are studying the critter," the Mote official said. "You actually want the critter to show up."

Thursday, March 17, 2011

Dr James Barnard wins Lee Kuan Yew Water Prize

Dr James Barnard wins Lee Kuan Yew Water Prize
By Joanne Chan | Posted: 17 March 2011 1723 hrs

SINGAPORE : The inventor of an eco-friendly method of treating used water has been named this year's Lee Kuan Yew Water Prize winner.

The international award recognises outstanding contributions towards solving global water problems.

It will be handed out at the Singapore International Water Week in July.

In fish farming, algae that grow in the water is an important part of the ecology - as a food source for the marine life. However, excessive algae bloom can quickly turn fatal.

Dr James Barnard, winner of the Lee Kuan Yew Water Prize, said: "Other organisms feed on the algae, fish feed on the other organisms, and of course we eat the fish. That is the normal chain of events.

"The main problem is when the system becomes imbalanced, the algae growth becomes excessive, and when it's excessive, it disturbs the water balance so the fish can no longer survive in it."

This happens when nutrients like nitrogen and phosphorus are not removed from used water before being discharged into lakes and rivers.

In 2008, the outbreak of algae bloom in waters off China's Qingdao disrupted the Olympics sailing competition and damaged marine life.

Dr Barnard's technology, known as Biological Nutrient Removal, uses micro-organisms already present in the water to remove the nutrients.

Pioneered in the 1970s, this technology is currently used in thousands of water treatment plants worldwide.

It is more eco-friendly compared to traditional treatments as it does away with the use of resource-intensive chemicals. It can also result in up to 90 per cent of cost savings.

The Lee Kuan Yew Water Prize received a record 72 nominations from 29 countries this year. Dr Barnard's technology stood out from the competition for his innovative and cost-effectiveness in treating used water.

Dr Barnard said he would donate the S$300,000 cash prize to charity. The South African native also hopes to use the money to improve school systems in his country.

Past winners include Professor Gatze Lettinga from the Netherlands for his anaerobic technology for used water treatment, and Dr Andrew Benedek for pioneering low-pressure membrane

Tuesday, March 15, 2011

Diatom and Oysters


by J. Bartholomew

From our good friend, J. Bartholomew, we have interesting news. Together with Dr. Hopkins, he is now engaged in oyster research at Biloxi, Miss. It seems that this bivalve delicacy is on the way out,or at least rapidly decreasing in numbers at this locality which is economically, as well as gastronomically, a great loss to the citizenry at large. It may be possible that polution by waste water from Freeport Sulphur Co. is the cause of the oyster demise; however, it may also be possible that there are other causes, hence, this research project.

One reason for which this project is most interesting to microscopists is the fact that young oysters find their main food supply in plankton of which diatoms are the most prominent inhabitants. One may almost say no diatoms , no oysters. Some curious observations have been made in this respect. Mr. Bartholomew reports that the Menhaden (a surface feeding fish of the herring family) is quite a consumer of diatoms. He writes as follows: "You will probably be astonished to know that a 200 millimeter beaker of Menhaden intestines will frequently yield, after cleaning 25 millimeter of diatoms. Years ago, I thought I was a collector but my hat is off to the Menhaden."

"It is possible to set up an oyster control under laboratory conditions, feed him for 24 hours in natural seawater rich in plankton, take him out at the end of the period, scrub him, sterilize him and put him into filtered sea water and let him deficate for 24 hours and then make complete diatom studies of what has actually passed through his intestines. These angles of course fascinate me. Of the 60 odd genera and perhaps 100 species, common in townet-takes and the studies of the mud bottom, darned if the little brat does not confine himself almost wholly to Melosira, several species Cosciusdiscus, goodness knows how many varied species and Navicula - virtually all the strictly linears he rejects and even among the Navicula will only pick the nearly oval shapes. Also in studying sizes, if the Cosciusdiscus, for instance, will average a hundred to one hundred and fifty microns in natural sea water, the little skunk will ingest nothing beyond 50 or 60 microns. We are now ready to set up pure cultures in Miguel solution and grow the genera and species that the oysters accept. We will then treat the cultures in various percentages of bleedwater to see how it affects the growth of the diatoms themselves!

Mr. Bartholomew is inviting our diatom interested readers to cooperate with him in this project, particularly the taxonomitical assistance would be helpful.If you feel you can be of help, kindly contact J. E. Nielsen, 5517 Drexel Ave., Chicago 37.


Thursday, March 10, 2011

Biogeochemical Cycles

A very comprehensive presentation on Biogeochemical cycles

Silicon, Carbon / Oxygen, Nitrogen, Sulfur cycles are discussed.

Monday, March 7, 2011

Arctic plankton blooms

Shifting spring: Arctic plankton blooming up to 50 days earlier now

A light micrograph shows plankton including water fleas (family Daphniidae).
A light micrograph shows plankton including water fleas (family Daphniidae). (Laguna Design)

Washington Post Staff Writer
Monday, March 7, 2011

Climate researchers have long warned that the Arctic is particularly vulnerable to global warming. The dramatic shrinking of sea ice in areas circling the North Pole highlights those concerns.

A new report finds that the disappearing ice has apparently triggered another dramatic event - one that could disrupt the entire ecosystem of fish, shellfish, birds and marine mammals that thrive in the harsh northern climate.

Each summer, an explosion of tiny ocean-dwelling plants and algae, called phytoplankton, anchors the Arctic food web.

But these vital annual blooms of phytoplankton are now peaking up to 50 days earlier than they did 14 years ago, satellite data show.

"The ice is retreating earlier in the Arctic, and the phytoplankton blooms are also starting earlier," said study leader Mati Kahru, an oceanographer at the Scripps Institution of Oceanography in San Diego.

Drawing on observations from three American and European climate satellites, Kahru and his international team studied worldwide phytoplankton blooms from 1997 through 2009. The satellites can spot the blooms by their color, as billions of the tiny organisms turn huge swaths of the ocean green for a week or two.

The blooms peaked earlier and earlier in 11 percent of the areas where Kahru's team was able to collect good data. Kahru said the impacted zones cover roughly 1 million square kilometers, including portions of the Foxe Basin and the Baffin Sea, which belong to Canada, and the Kara Sea north of Russia.

"The trend is obvious and significant, and in my mind there is no doubt it is related to the retreat of the ice," said Kahru, who published the work in the journal Global Change Biology.In the late 1990s, phytoplankton blooms in these areas hit their peak in September, only after a summer's worth of relative warmth had melted the edges of the polar ice cap. But by 2009 the blooms' peaks had shifted to early July.

"A 50-day shift is a big shift," said plankton researcher Michael Behrenfeld of Oregon State University, who was not involved in the study. "As the planet warms, the threat is that these changes seen closer to land may spread across the entire Arctic."

Ecologists worry that the early blooms could unravel the region's ecosystem and "lead to crashes of the food web," said William Sydeman, who studies ocean ecology as president of the nonprofit Farallon Institute in Petaluma, Calif.

When phytoplankton explode in population during the blooms, tiny animals called zooplankton - which include krill and other small crustaceans - likewise expand in number as they harvest the phytoplankton. Fish, shellfish and whales feed on the zooplankton, seabirds snatch the fish and shellfish, and polar bears and seals subsist on those species.

The timing of this sequential harvest is programmed into the reproductive cycles of many animals, Sydeman said. "It's all about when food is available." So the disrupted phytoplankton blooms could "have cascading effects up the food web all the way to marine mammals."

But the Arctic food web is poorly studied, and so any resulting decline in fish, seabirds and mammals will be difficult to spot.

As the Arctic Ocean north becomes less and less icy, commercial fisherman have begun eyeing these vast, untapped waters as an adjunct to the famously rich fishing grounds of the subarctic Bering Sea, west of Alaska.

But in 2009, the U.S. body overseeing fishing in the region, the North Pacific Fishery Management Council, banned commercial fishing in the Arctic Ocean, citing a lack of knowledge about how many - or even what kind - of fish live there.

"There are no catches authorized because we don't know enough about the fish populations there to set a quota," said Julie Speegle, a spokeswoman for the Alaska office of the National Marine Fisheries Service.

Last week, that service reported results from the first fish survey in 30 years of the Beaufort Sea, an arm of the Arctic Ocean north of Alaska. The survey found sizeable populations of several commercially valuable species, including pollock, Pacific cod and snow crab.

Last week, the National Snow and Ice Data Center, in Boulder, Colo., reported that in February, Arctic sea ice covered a smaller area than ever seen in that month, tying with February 2005 as the most ice-free February since satellites began tracking Arctic ice in 1979.How these populations will respond to the ever-earlier plankton blooms is a big unknown, Sydeman said. But other research has shown that northern Atlantic cod populations crash when plankton blooms in that region shift in time.

The annual average Arctic sea ice coverage has decreased about 12 percent since then, a trend that appears to be accelerating, said Walt Meier, a research scientist at the center. Summer ice coverage has declined even more dramatically, he said, with the Arctic losing almost a third of its late-summer ice over the past 30 years.

Zeolite for lake remediation

Lake Okaro: core studies

The efficacy of modified zeolite on blocking the release of phosphorus from lake sediments was evaluated prior to conducting a whole lake trial (Gibbs and Özkundakci, 2010). Two cores were treated with two different grain sizes and dose rates of modified zeolite under both aerobic or anoxic water conditions.

The applied modified zeolite had a high affinity for phosphorus with a thin layer (~2mm) completely blocking the release of phosphorus from the sediment under aerobic and anoxic conditions. It also removed phosphorus from the overlying water in contact with the capping layer. Interestingly, it also absorbed mercury and arsenic from the geothermally influenced Lake Okaro sediments. Modified zeolite also completely blocked the release of ammoniacal nitrogen from the sediments as well as ammonia from the water in contact with it.

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Lake Okaro: 2007 application

Over four days in September 2007, Lake Okaro was treated with about 110 tonnes of modified zeolite to form a sediment cap. This modified zeolite was applied where the lake depth exceeded 5 m, equivalent to 20 ha of lakebed. Environment Bay of Plenty contracted NIWA to independently evaluate the efficacy of modified zeolite as a phosphate-inactivation agent and to identify any adverse effects (Gibbs et al., 2007). Their results demonstrated the modified zeolite applied as a capping agent is capable of blocking phosphorus released from the sediment and overlying water.

Despite the rapid reduction in lake water total phosphate following modified zeolite application, the trophic state level of the lake remained constant (Özkundakci et al. 2010b). The observed significant decline in P concentration in the bottom waters of Lake Okaro in response to the modified zeolite application suggests that sediment capping was the most effective amongst all of the restoration procedures carried out in this lake, which included a constructed wetland, farm nutrient management, and the riparian restoration.

A follow-up study in 2009 (Gibbs, 2009) showed the modified zeolite adsorbed about 50% of the available phosphorus in the sediment over 18 months from the September 20017 application. The P content in the sediment declined from 3.15g m-2 to around 1.5 g m -2 a reduction of around 50%. Measuring the P content of modified zeolite granules recovered from the lake indicated that most of the P reduction could be attributed to uptake by the modified zeolite.

The researchers speculated that the large grain size of the modified zeolite sank in to the sediment and effectively was only able to remove P from the sediment surrounding it. A further trial in 2009 used a smaller grain size and was expected to result in a more effective sediment cap.

The 2007 sediment capping of Lake Okaro using modified zeolite did not have any undesirable effect on zooplankton or phytoplankton community structure (Özkundakci, et al. 2009). In the long term, the zooplankton community is expected to change in composition with a reduction in nutrients and algal levels. Modified zeolite application had no effect on fish health in Lake Okaro (Landman and Ling, 2010).

Lake Okaro: 2009 application

In a second application in August 2009, the lake was treated with a further 44 tonnes of modified zeolite applied as a slurry (Gibbs, 2009). This application had a finer grain size (0.3-0.5mm) compared with the 2007 application (1-3mm). This fine grain size was able to absorb phosphorus from the water column, possibly a function of the lower settling rate. Results have not yet been reported on the efficacy of this application of modified zeolite as a sediment cap. There was strong evidence that the finer modified zeolite slurry acted as a flocculant as it precipitated organic matter, including algae out of the water.

Lake Rotorua trials

As part of the programme for the restoration of Rotorua lakes, Environment Bay of Plenty studied the use of sediment capping materials to reduce the amount of dissolved reactive phosphorus in the lake water column from sediment release. Of four P-inactivation products trialled (Gibbs et al. 2008), modified zeolite had a high P-binding rate and was the only capping material which reduced the released of ammonia nitrogen from the sediments.

The potential for modified zeolite as a sediment cap in Lake Rotorua has been trialled. Laboratory trials by NIWA and the University of Waikato (Gibbs and Hamilton, 2009) compared modified zeolite with two other potential sediment cap materials. All three performed well in the lab and suggested no phosphorus would be released from sediments following application of these capping materials.

Currently, consents are being applied for trials in a limited area in Lake Rotorua. A challenge will be the uneven application of the modified zeolite on the lake bottom due to lake depth, drifts and currents. Work is being progressed by Blue Pacific Minerals in this area with a site-specific water dispersible granule being developed.

Wednesday, March 2, 2011

Reviving 100-Year-Old Resting Spores of Diatoms

Reviving 100-Year-Old Resting Spores of Diatoms

ScienceDaily (Feb. 28, 2011)

Diatoms account for a large proportion of the phytoplankton found in the water, and live both in the open sea and in freshwater lakes. By reviving 100-year-old spores that had laid buried and inactive in bottom sediment, researchers at the University of Gothenburg, Sweden, have shown that diatoms are also genetically stable and survival artists.

Recent research has shown that diatoms exhibit great genetic differences and that they occur in discrete populations, which means that they multiply sexually to a greater extent than previously believed. What makes diatoms special is that if the environment they live in becomes too inhospitable they form resting spores, which gather in sediment at the bottom of the sea. When conditions improve, the spores can be revived.

The study concerned is based on a sample of sediment from a highly eutrophic Danish fjord on the east coast of Jutland, Mariager Fjord, whose anoxic bottoms and bottom sediments today do not show any signs of life. After dating the different layers of a sediment core, the researchers took small pieces of sediment from various depths and transferred them to an environment favourable to diatoms. This enabled them to revive resting spores.

"We revived hundreds of genetic individuals of diatoms and induced them to start dividing again and to form cloned cultures. The oldest are more than 100 years old, the youngest quite fresh. We then identified the revived individuals genetically," says Anna Godhe of the Department of Marine Ecology at the University of Gothenburg.

40 000 generations of diatoms

As diatoms normally divide once a day, this means that for a diatom a period of 100 years is equivalent to 40 000 generations. In human terms, this means genetic material equivalent to around 800 000 years.

"We found certain differences between the algae that went into a state of rest at the start of the 20th century compared with those that formed resting spores when the eutrophication was at its worst and the freshest ones of all, but the individuals are for the most part very homogeneous throughout the sediment core, that's to say 40 000 generations of diatoms."

No traces of genetic impact over 100 years

"The most exciting thing of all in the whole study is that there are no traces at all of genetic impact from the open sea population on the diatoms in Mariager Fjord during the 100 years we have studied, despite a constant influx of diatoms from the Kattegatt with the surface water. Not one out of all the millions upon millions of diatoms that have found their way into the fjord from the Kattegatt has become established and continued to grow in the fjord.

The researchers believe that this is due to the fact that the algae that live inside the fjord are so superbly well adapted to the fjord environment and that there are so many of them (millions per litre of water, thousands per gram of sediment) that colonisers from outside are rapidly out-competed.

The article Hundred years of genetic structure in a sediment revived diatom population has been published in the scientific journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). The study has been conducted by Karolina Härnström and Anna Godhe at the University of Gothenburg in cooperation with Marianne Ellegaard and Thorbjørn J. Andersen at Copenhagen University.

Tuesday, March 1, 2011

Algal Bloom off New Zealand coast

To an oceanographer, the ocean around New Zealand in the summertime provides a fascinating field of study. This image, taken on February 10, 2011, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, cries out for closer investigation from sea level. The swirls of turquoise and green map out a large phytoplankton bloom along the shores of New Zealand’s South Island. From a ship on the water, a scientist would be able to sample the bloom to find out just what type of plankton are growing and how the bloom affects the region’s biology.

Some ocean scientists, however, come to New Zealand with different waters in mind. Christchurch serves as a staging ground for Antarctica, and that was the departure point for NASA Ocean Color staff member, Aimee Neeley, who recently left the city for McMurdo Station, Antarctica. Neeley is currently in the Southern Ocean on the research ship, R/V Nathaniel B. Palmer.

Over the next several weeks, Neeley will be taking measurements that will help scientists interpret ocean color observations, like the above image, from the MODIS sensors. She is keeping a blog to share her Antarctic experiences with the community. She will discuss daily life on an oceanographic vessel and describe the scientific questions she is working to answer.

NASA image by Norman Kuring, Ocean Color Team. Caption by Norman Kuring, adapted from New Zealand: Antarctic staging ground.

Aqua - MODIS