http://www.abc.net.au/news/stories/2010/03/31/2860925.htm
Lack of oxygen kills fish
Posted Wed Mar 31, 2010 9:49am AEDT
MAP: Pinjarra 6208
Authorities are blaming last week's storm for the deaths of about 1,000 fish near Pinjarra, south of Perth.
The bream were found along the Murray River near the Dandalup River mouth.
The Department of Water says there was a lack of oxygen in the water after fresh water was flushed into the river by the storm.
The Department's Leon Brouwer says the fish would have suffocated as a result.
"The rainfall event causes a lot of organic matter and other things to flow down through the water column, so the oxygen demand in the water column is very high and it essentially just strips out what available oxygen there is in the water column in a very quick time.
"Some species have been seen, like mullet and herring, swimming upstream from the areas we located the fish kill but others that do get caught out in those pockets where there's no oxygen can suffocate."
Fish kills have also been reported in the Swan and Canning rivers over the past week.
Wednesday, March 31, 2010
Tuesday, March 30, 2010
Lake Okeechobee Performance Measure - Diatom / Cyanobacteria Ratio
http://www.evergladesplan.org/pm/recover/recover_docs/et/lo_pm_cyano-diatom.pdf
Lake Okeechobee Performance Measure
Diatom/Cyanobacteria Ratio
Last Date Revised: March 7, 2007
Acceptance Status: Accepted
1.0 Desired Restoration Condition
The target is to substantially reduce the dominance of cyanobacteria relative to diatoms. This can be expressed as a numeric target of having a long-term pelagic ratio of biovolume (diatoms: cyanobacteria) greater than 1.5:1.
2.0 Justification
Studies of phytoplankton taxonomic structure of Lake Okeechobee in the 1970s indicated that the community was dominated by diatoms; today the community is dominated by pollution-tolerant bloom-forming cyanobacteria (Havens et al. 1996). The five-year mean diatom to cyanobacteria ratio for 2000-2005 was 0.63 (SFER, 2006). If phosphorus loads are substantially reduced the percentage of the community comprised of cyanobacteria should decline (LATHROP et al., 1998).
--------------------------
The target of this approach is to reduce phosphorus to reduce the cyanobacteria population. The alternative of increasing Silica to increase Diatoms population is not being discussed. This is an easier solution.
Lake Okeechobee Performance Measure
Diatom/Cyanobacteria Ratio
Last Date Revised: March 7, 2007
Acceptance Status: Accepted
1.0 Desired Restoration Condition
The target is to substantially reduce the dominance of cyanobacteria relative to diatoms. This can be expressed as a numeric target of having a long-term pelagic ratio of biovolume (diatoms: cyanobacteria) greater than 1.5:1.
2.0 Justification
Studies of phytoplankton taxonomic structure of Lake Okeechobee in the 1970s indicated that the community was dominated by diatoms; today the community is dominated by pollution-tolerant bloom-forming cyanobacteria (Havens et al. 1996). The five-year mean diatom to cyanobacteria ratio for 2000-2005 was 0.63 (SFER, 2006). If phosphorus loads are substantially reduced the percentage of the community comprised of cyanobacteria should decline (LATHROP et al., 1998).
--------------------------
The target of this approach is to reduce phosphorus to reduce the cyanobacteria population. The alternative of increasing Silica to increase Diatoms population is not being discussed. This is an easier solution.
Monday, March 29, 2010
Harmful Algal blooms increasing and causing low DO levels
http://blog.cleantechies.com/2010/03/29/ocean-oxygen-catastrophic-change/
Lower Ocean Oxygen Levels Predict Catastrophic Change
Published on March 29th, 2010 by Celsias
Posted in Climate Change & Carbon Emissions, Pollution, Water Resources
Leave comment »
There is a cascade failure going on in the world’s oceans that promises nothing but trouble in the future, and the problem stems in part from agricultural practices developed over the last half-decade aimed at growing more food on the same amount of land to feed rising populations.
A cascade failure is the progressive collapse of an integral system. Many scientists also call them negative feedback loops, in that unfortunate situations reinforce one another, precipitating eventual and sometimes complete failure.
The agricultural practices relate to “factory farming,” in which farmers grow crops using more and more chemical fertilizers, specifically nitrogen and phosphorus, which are the first two ingredients (chemical symbols N and P) listed on any container or bag of fertilizer. The last is potassium, or K.
But farmers aren’t the only culprits. Lawn enthusiasts add to the problem with their massive applications of fertilizer designed to maintain a species of plant that doesn’t provide either food or habitat, and is grown merely to add prestige. And groundskeepers at parks and large corporate headquarters are equally guilty. In fact, a whole generation needs to rethink its addiction to lawns.
Whoever is guilty of applying the fertilizer, these megadoses are eventually washed off the fields and lawns and into waterways. From there, they migrate to the nearest large bodies of water, where they spark such tremendous and unnatural growth in aquatic plants that the result is eutrophication , or lack of oxygen in the water as bacteria act to reduce the sheer mass of dying organic matter.
One of these aquatic growths is algae, or phytoplankton. Moderate algal growth can produce higher fish yields and actually benefit lakes and oceans, but over-stimulation leads to a whole host of problems whose integral relationship to one another threatens not only aquatic but human life.
A classic example would be the Baltic Sea, where phytoplankton are raging out of control. The Baltic Sea is, as a result, home to seven out of ten of the world’s largest “dead zones,” aquatic areas where nothing survives.
One of the other three is the Gulf of Mexico, where a 2008 dead zone the size of Massachusetts is expected to grow in future years thanks to the U.S. government’s biofuel mandate. Most of the crops for biofuel are grown along the Mississippi River, which drains directly into this dead zone.
In the Baltic, as elsewhere, overfishing has exacerbated the problem. Fish feed on smaller aquatic organisms, which themselves feed on the algae. Take the fish out of the equation, and the balance is lost. It’s very much like removing the wolves that keep down the deer population in order to protect the sheep, and it doesn’t work in the ocean any better than it works on land.
Once the algal blooms begin to thrive, they block sunlight to deeper water and begin to kill off seaweeds and other aquatic plants which are home to fish species. The dying plants then consume more oxygen as bacteria consume them. And, as the seaweeds die, the few remaining fish and shellfish species move away, deprived of habitat.
This is a classic example of a negative feedback loop, and it is reinforced by every meal of fish, every instance of Scotts lawn fertilizer, and every ear of corn grown with a little help from Cargill or Dow, to name just two multinational fertilizer manufacturers.
Another example is occurring in the Pacific Northwest , along the West Coast of the United States, where — in Washington State, Oregon, and even Northern California — piles of Dungeness crab shells on the ocean floor mark areas of severe eutrophication well within sight of land.
Elsewhere along the Pacific shoreline, bird deaths – ranging from pelicans to sea ducks – predict a failure in the natural world that can’t help but reverberate among the planet’s prime predator, man.
These areas of eutrophication have always been present, but their spread – from one or two areas to miles of coastal waters – indicates a larger problem that is likely about to overwhelm not only the fishing industry and tourism but the existence of oceans as living entities.
As Oregon State University ocean sciences professor Jack Barth notes, the once-scarce areas of low oxygen have become the “new normal”, with old areas repeating and new areas cropping up every year. In many of these areas, oxygen levels are 30 percent lower than they were a mere half-decade ago.
Not all algal blooms are harmful or noxious, of course. But those which occur in response to eutrophication do seem to be, and these – known as HABs, or harmful algal blooms – include pseudo-nitzschia producing algae, which deliver a neurotoxin called domoic acid that can kill humans, birds and aquatic mammals that eat the affected shellfish; golden algae, which under certain conditions produce toxins that cause massive fish and bivalve (clams, mussels, oysters) kills; brown tides, which are not toxic in themselves but create aquatic conditions that can kill fish larvae; red tides, which produce brevetoxins that can affect breathing and sometimes trigger fatal, respiratory illnesses in humans; and blue-green algae, or cyanobacteria, which can form dense colonies that cause water to smell and become toxic to fish, pets and humans.
This last, which has spread from Texas to Minnesota, has led to livestock deaths in the former. In the latter, where having a lake home is a sign of prestige, many homeowners have been forced to sell at a loss to get away from once-pristine lakes so smelly and toxic that dozens of pet dogs have been killed drinking the water.
Lower oxygen levels in oceans are very attractive to one species; jellyfish, and these odd creatures with their many tentacles and poisonous sting thrive under such conditions. In fact, jellyfish have few predators except man, and those few (tuna, sharks, swordfish, a carnivorous coral , one species of Pacific salmon and the leatherback turtle) are all at great risk of extinction because of eutrophication and its related conditions, pollution, overfishing and climate change.
As one of the most prolific species in the ocean, and certainly one with a long history (the species has been around since the Cambrian), jellyfish will probably take over the oceans if things continue as they have been going since the 1960s. This is good news for the Japanese, Chinese and other Oriental cultures who regard the slimy beast as a delicacy.
For the rest of us, jellyfish are an acquired taste, and one we had better acquire if we want to keep eating seafood. Either that, or we can support legislation that, in the U.S. at least, promises some relief through research, monitoring and rule-making regarding the Great Lakes and both coasts.
Article by Jeanne Roberts appearing courtesy Celsias.
---------------------------------------------------
This article seems to contradict the NASA finding that Phytoplankton population is decreasing.
www.gsfc.nasa.gov/topstory/20020801plankton2.html
It also contradicts the old paper of 1958 by Prof Ryther that Diatom blooms cause high Dissolved Oxygen level.
http://www.jstor.org/stable/1539030
The truth is perhaps that Diatoms blooms have decreased and other algal blooms have increased. No one seems to be monitoring this change.
Usually Chlorophyll 'a' is measured, however, Chlorophyll a is present in all types of algae, so it is not an effective means to identify useful vs harmful algae.
Lower Ocean Oxygen Levels Predict Catastrophic Change
Published on March 29th, 2010 by Celsias
Posted in Climate Change & Carbon Emissions, Pollution, Water Resources
Leave comment »
There is a cascade failure going on in the world’s oceans that promises nothing but trouble in the future, and the problem stems in part from agricultural practices developed over the last half-decade aimed at growing more food on the same amount of land to feed rising populations.
A cascade failure is the progressive collapse of an integral system. Many scientists also call them negative feedback loops, in that unfortunate situations reinforce one another, precipitating eventual and sometimes complete failure.
The agricultural practices relate to “factory farming,” in which farmers grow crops using more and more chemical fertilizers, specifically nitrogen and phosphorus, which are the first two ingredients (chemical symbols N and P) listed on any container or bag of fertilizer. The last is potassium, or K.
But farmers aren’t the only culprits. Lawn enthusiasts add to the problem with their massive applications of fertilizer designed to maintain a species of plant that doesn’t provide either food or habitat, and is grown merely to add prestige. And groundskeepers at parks and large corporate headquarters are equally guilty. In fact, a whole generation needs to rethink its addiction to lawns.
Whoever is guilty of applying the fertilizer, these megadoses are eventually washed off the fields and lawns and into waterways. From there, they migrate to the nearest large bodies of water, where they spark such tremendous and unnatural growth in aquatic plants that the result is eutrophication , or lack of oxygen in the water as bacteria act to reduce the sheer mass of dying organic matter.
One of these aquatic growths is algae, or phytoplankton. Moderate algal growth can produce higher fish yields and actually benefit lakes and oceans, but over-stimulation leads to a whole host of problems whose integral relationship to one another threatens not only aquatic but human life.
A classic example would be the Baltic Sea, where phytoplankton are raging out of control. The Baltic Sea is, as a result, home to seven out of ten of the world’s largest “dead zones,” aquatic areas where nothing survives.
One of the other three is the Gulf of Mexico, where a 2008 dead zone the size of Massachusetts is expected to grow in future years thanks to the U.S. government’s biofuel mandate. Most of the crops for biofuel are grown along the Mississippi River, which drains directly into this dead zone.
In the Baltic, as elsewhere, overfishing has exacerbated the problem. Fish feed on smaller aquatic organisms, which themselves feed on the algae. Take the fish out of the equation, and the balance is lost. It’s very much like removing the wolves that keep down the deer population in order to protect the sheep, and it doesn’t work in the ocean any better than it works on land.
Once the algal blooms begin to thrive, they block sunlight to deeper water and begin to kill off seaweeds and other aquatic plants which are home to fish species. The dying plants then consume more oxygen as bacteria consume them. And, as the seaweeds die, the few remaining fish and shellfish species move away, deprived of habitat.
This is a classic example of a negative feedback loop, and it is reinforced by every meal of fish, every instance of Scotts lawn fertilizer, and every ear of corn grown with a little help from Cargill or Dow, to name just two multinational fertilizer manufacturers.
Another example is occurring in the Pacific Northwest , along the West Coast of the United States, where — in Washington State, Oregon, and even Northern California — piles of Dungeness crab shells on the ocean floor mark areas of severe eutrophication well within sight of land.
Elsewhere along the Pacific shoreline, bird deaths – ranging from pelicans to sea ducks – predict a failure in the natural world that can’t help but reverberate among the planet’s prime predator, man.
These areas of eutrophication have always been present, but their spread – from one or two areas to miles of coastal waters – indicates a larger problem that is likely about to overwhelm not only the fishing industry and tourism but the existence of oceans as living entities.
As Oregon State University ocean sciences professor Jack Barth notes, the once-scarce areas of low oxygen have become the “new normal”, with old areas repeating and new areas cropping up every year. In many of these areas, oxygen levels are 30 percent lower than they were a mere half-decade ago.
Not all algal blooms are harmful or noxious, of course. But those which occur in response to eutrophication do seem to be, and these – known as HABs, or harmful algal blooms – include pseudo-nitzschia producing algae, which deliver a neurotoxin called domoic acid that can kill humans, birds and aquatic mammals that eat the affected shellfish; golden algae, which under certain conditions produce toxins that cause massive fish and bivalve (clams, mussels, oysters) kills; brown tides, which are not toxic in themselves but create aquatic conditions that can kill fish larvae; red tides, which produce brevetoxins that can affect breathing and sometimes trigger fatal, respiratory illnesses in humans; and blue-green algae, or cyanobacteria, which can form dense colonies that cause water to smell and become toxic to fish, pets and humans.
This last, which has spread from Texas to Minnesota, has led to livestock deaths in the former. In the latter, where having a lake home is a sign of prestige, many homeowners have been forced to sell at a loss to get away from once-pristine lakes so smelly and toxic that dozens of pet dogs have been killed drinking the water.
Lower oxygen levels in oceans are very attractive to one species; jellyfish, and these odd creatures with their many tentacles and poisonous sting thrive under such conditions. In fact, jellyfish have few predators except man, and those few (tuna, sharks, swordfish, a carnivorous coral , one species of Pacific salmon and the leatherback turtle) are all at great risk of extinction because of eutrophication and its related conditions, pollution, overfishing and climate change.
As one of the most prolific species in the ocean, and certainly one with a long history (the species has been around since the Cambrian), jellyfish will probably take over the oceans if things continue as they have been going since the 1960s. This is good news for the Japanese, Chinese and other Oriental cultures who regard the slimy beast as a delicacy.
For the rest of us, jellyfish are an acquired taste, and one we had better acquire if we want to keep eating seafood. Either that, or we can support legislation that, in the U.S. at least, promises some relief through research, monitoring and rule-making regarding the Great Lakes and both coasts.
Article by Jeanne Roberts appearing courtesy Celsias.
---------------------------------------------------
This article seems to contradict the NASA finding that Phytoplankton population is decreasing.
www.gsfc.nasa.gov/topstory/20020801plankton2.html
It also contradicts the old paper of 1958 by Prof Ryther that Diatom blooms cause high Dissolved Oxygen level.
http://www.jstor.org/stable/1539030
The truth is perhaps that Diatoms blooms have decreased and other algal blooms have increased. No one seems to be monitoring this change.
Usually Chlorophyll 'a' is measured, however, Chlorophyll a is present in all types of algae, so it is not an effective means to identify useful vs harmful algae.
Phytoplankton population declining
www.gsfc.nasa.gov/topstory/20020801plankton2.html
SATELLITES SEE BIG CHANGES SINCE 1980s IN KEY ELEMENT OF OCEAN'S FOOD CHAIN
Since the early 1980s, ocean phytoplankton concentrations that drive the marine food chain have declined substantially in many areas of open water in Northern oceans, according to a comparison of two datasets taken from satellites. At the same time, phytoplankton levels in open water areas near the equator have increased significantly. Since phytoplankton are especially concentrated in the North, the study found an overall annual decrease in phytoplankton globally.
The authors of the study, Watson Gregg, of NASA's Goddard Space Flight Center, Greenbelt, Md., and Margarita Conkright, a scientist at the National Oceanic and Atmospheric Administration's (NOAA) National Oceanographic Data Center, Silver Spring, Md., also discovered what appears to be an association between more recent regional climate changes, such as higher sea surface temperatures and reductions in surface winds, and areas where phytoplankton levels have dropped.
Phytoplankton consist of many diverse species of microscopic free-floating marine plants that serve as food to other ocean-living forms of life. "The whole marine food chain depends on the health and productivity of the phytoplankton," Gregg said.
The researchers compared two sets of satellite data -- one from 1979 to 1986 and the other from 1997 to 2000 -- that measured global ocean chlorophyll, the green pigment in plants that absorbs the Sun's rays for energy during photosynthesis. The earlier dataset came from the Coastal Zone Color Scanner (CZCS) aboard NASA's Nimbus-7 satellite, while the latter dataset was from the Sea-Viewing Wide Field of View Sensor (SeaWiFS) on the OrbView-2 satellite.
The researchers re-analyzed the CZCS data with the same processing methods used for the SeaWiFS data, and then blended both satellite measurements with surface observations of chlorophyll from ocean buoys and research vessels over corresponding time periods. By doing so, the researchers reduced errors and made the two records compatible.
Results indicated that phytoplankton in the North Pacific Ocean dropped by over 30 percent during summer from the mid-80s to the present. Phytoplankton fell by 14 percent in the North Atlantic Ocean over the same time period.
Also, summer plankton concentrations rose by over 50 percent in both the Northern Indian and the Equatorial Atlantic Oceans since the mid-80s. Large areas of the Indian Ocean showed substantial increases during all four seasons.
"This is the first time that we are really talking about the ocean chlorophyll and showing that the ocean's biology is changing, possibly as a result of climate change," said Conkright. The researchers add that it remains unclear whether the changes are due to a longer-term climate change or a shorter-term ocean cycle.
Phytoplankton thrive when sunlight is optimal and nutrients from lower layers of the ocean get mixed up to the surface. Higher sea surface temperatures can reduce the availability of nutrients by creating a warmer surface layer of water. A warmer ocean surface layer reduces mixing with cooler, deeper nutrient-rich waters. Throughout the year, winds can stir up surface waters, and create upwelling of nutrients from below, which also add to blooms. A reduction in winds can also limit the availability of nutrients.
For example, in the North Pacific, summer sea surface temperatures were .4 degrees Celsius (.7 Fahrenheit) warmer from the early 1980s to 2000, and average spring wind stresses on the ocean decreased by about 8 percent, which may have caused the declines in summer plankton levels in that region.
Phytoplankton currently account for half the transfer of carbon dioxide from the atmosphere back into the biosphere by photosynthesis, a process in which plants absorb carbon dioxide (CO2) from the air for growth. Since carbon dioxide acts as a heat-trapping gas in the atmosphere, the role phytoplankton play in removing carbon dioxide from the atmosphere helps reduce the rate at which CO2 accumulates in the atmosphere, and may help mitigate global warming.
The paper appears in the current issue of Geophysical Research Letters.
SATELLITES SEE BIG CHANGES SINCE 1980s IN KEY ELEMENT OF OCEAN'S FOOD CHAIN
Since the early 1980s, ocean phytoplankton concentrations that drive the marine food chain have declined substantially in many areas of open water in Northern oceans, according to a comparison of two datasets taken from satellites. At the same time, phytoplankton levels in open water areas near the equator have increased significantly. Since phytoplankton are especially concentrated in the North, the study found an overall annual decrease in phytoplankton globally.
The authors of the study, Watson Gregg, of NASA's Goddard Space Flight Center, Greenbelt, Md., and Margarita Conkright, a scientist at the National Oceanic and Atmospheric Administration's (NOAA) National Oceanographic Data Center, Silver Spring, Md., also discovered what appears to be an association between more recent regional climate changes, such as higher sea surface temperatures and reductions in surface winds, and areas where phytoplankton levels have dropped.
Phytoplankton consist of many diverse species of microscopic free-floating marine plants that serve as food to other ocean-living forms of life. "The whole marine food chain depends on the health and productivity of the phytoplankton," Gregg said.
The researchers compared two sets of satellite data -- one from 1979 to 1986 and the other from 1997 to 2000 -- that measured global ocean chlorophyll, the green pigment in plants that absorbs the Sun's rays for energy during photosynthesis. The earlier dataset came from the Coastal Zone Color Scanner (CZCS) aboard NASA's Nimbus-7 satellite, while the latter dataset was from the Sea-Viewing Wide Field of View Sensor (SeaWiFS) on the OrbView-2 satellite.
The researchers re-analyzed the CZCS data with the same processing methods used for the SeaWiFS data, and then blended both satellite measurements with surface observations of chlorophyll from ocean buoys and research vessels over corresponding time periods. By doing so, the researchers reduced errors and made the two records compatible.
Results indicated that phytoplankton in the North Pacific Ocean dropped by over 30 percent during summer from the mid-80s to the present. Phytoplankton fell by 14 percent in the North Atlantic Ocean over the same time period.
Also, summer plankton concentrations rose by over 50 percent in both the Northern Indian and the Equatorial Atlantic Oceans since the mid-80s. Large areas of the Indian Ocean showed substantial increases during all four seasons.
"This is the first time that we are really talking about the ocean chlorophyll and showing that the ocean's biology is changing, possibly as a result of climate change," said Conkright. The researchers add that it remains unclear whether the changes are due to a longer-term climate change or a shorter-term ocean cycle.
Phytoplankton thrive when sunlight is optimal and nutrients from lower layers of the ocean get mixed up to the surface. Higher sea surface temperatures can reduce the availability of nutrients by creating a warmer surface layer of water. A warmer ocean surface layer reduces mixing with cooler, deeper nutrient-rich waters. Throughout the year, winds can stir up surface waters, and create upwelling of nutrients from below, which also add to blooms. A reduction in winds can also limit the availability of nutrients.
For example, in the North Pacific, summer sea surface temperatures were .4 degrees Celsius (.7 Fahrenheit) warmer from the early 1980s to 2000, and average spring wind stresses on the ocean decreased by about 8 percent, which may have caused the declines in summer plankton levels in that region.
Phytoplankton currently account for half the transfer of carbon dioxide from the atmosphere back into the biosphere by photosynthesis, a process in which plants absorb carbon dioxide (CO2) from the air for growth. Since carbon dioxide acts as a heat-trapping gas in the atmosphere, the role phytoplankton play in removing carbon dioxide from the atmosphere helps reduce the rate at which CO2 accumulates in the atmosphere, and may help mitigate global warming.
The paper appears in the current issue of Geophysical Research Letters.
Friday, March 26, 2010
Diatoms, Primary Productivity, Fish
The Dynamics of a Diatom Bloom
J. H. Ryther, C. S. Yentsch, E. M. Hulburt and R. F. Vaccaro
Biological Bulletin, Vol. 115, No. 2 (Oct., 1958), pp. 257-268
Published by: Marine Biological Laboratory
Stable URL: http://www.jstor.org/stable/1539030
Photosynthesis and Fish Production in the Sea
http://www.icess.ucsb.edu/~davey/Geog158/Readings/RytherScience1969.pdf
The production of organic matter and its conversion to higher forms of life vary throughout the world ocean.
John H. Ryther
Science, VOL. 166, 3 October 1969
The result has been modification of the estimate of primary production in the
world ocean from 1.2 to 1.5 x 10 * 10 tons of carbon fixed per year (5) to a new
figure, 1.5 to 1.8 x 10 * 10 tons (18 billion tons).
Attempts have also been made by Steemann Nielsen and Jensen (5), Ryther (8), and Koblentz-Mishke et al. (7) to assign specific levels or ranges of productivity to different parts of the ocean. Although the approach was somewhat different in each case, in general the agreement between the three was good and, with appropriate condensation and combination, permit the following conclusions.
1) Annual primary production in the open sea varies, for the most part, between
25 and 75 grams of carbon fixed per square meter and averages about 50 grams of carbon per square meter per year. This is true for roughly 90 percent of the ocean, an area of 326 x 106 square kilometers.
J. H. Ryther, C. S. Yentsch, E. M. Hulburt and R. F. Vaccaro
Biological Bulletin, Vol. 115, No. 2 (Oct., 1958), pp. 257-268
Published by: Marine Biological Laboratory
Stable URL: http://www.jstor.org/stable/1539030
Photosynthesis and Fish Production in the Sea
http://www.icess.ucsb.edu/~davey/Geog158/Readings/RytherScience1969.pdf
The production of organic matter and its conversion to higher forms of life vary throughout the world ocean.
John H. Ryther
Science, VOL. 166, 3 October 1969
The result has been modification of the estimate of primary production in the
world ocean from 1.2 to 1.5 x 10 * 10 tons of carbon fixed per year (5) to a new
figure, 1.5 to 1.8 x 10 * 10 tons (18 billion tons).
Attempts have also been made by Steemann Nielsen and Jensen (5), Ryther (8), and Koblentz-Mishke et al. (7) to assign specific levels or ranges of productivity to different parts of the ocean. Although the approach was somewhat different in each case, in general the agreement between the three was good and, with appropriate condensation and combination, permit the following conclusions.
1) Annual primary production in the open sea varies, for the most part, between
25 and 75 grams of carbon fixed per square meter and averages about 50 grams of carbon per square meter per year. This is true for roughly 90 percent of the ocean, an area of 326 x 106 square kilometers.
Tuesday, March 23, 2010
Diatomaceous earth
Many uses of Diatomaceous earth
http://www.agrisilica.co.za/diatomsconcentrate.html
http://www.diatoms.co.za/downloads/ENGBrochure.pdf
http://www.durhamhens.co.uk/Diatom.html
http://www.agrisilica.co.za/diatomsconcentrate.html
http://www.diatoms.co.za/downloads/ENGBrochure.pdf
http://www.durhamhens.co.uk/Diatom.html
Sunday, March 21, 2010
Dan Barber - How I fell in Love with a Fish
TED Video
http://www.ted.com/talks/dan_barber_how_i_fell_in_love_with_a_fish.html
Chef Dan Barber squares off with a dilemma facing many chefs today: how to keep fish on the menu. With impeccable research and deadpan humor, he chronicles his pursuit of a sustainable fish he could love, and the foodie's honeymoon he's enjoyed since discovering an outrageously delicious fish raised using a revolutionary farming method in Spain.
Dan Barber is the chef at New York's Blue Hill restaurant, and Blue Hill at Stone Barns in Westchester, where he practices a kind of close-to-the-land cooking married to agriculture and stewardship of the earth. As described on Chez Pim: "Stone Barns is only 45 minutes from Manhattan, but it might as well be a whole different universe. A model of self-sufficiency and environmental responsibility, Stone Barns is a working farm, ranch, and a three-Michelin-star-worthy restaurant." It's a vision of a new kind of food chain.
Barber's philosophy of food focuses on pleasure and thoughtful conservation -- on knowing where the food on your plate comes from and the unseen forces that drive what we eat. He's written on US agricultural policies, asking for a new vision that does not throw the food chain out of balance by subsidizing certain crops at the expense of more appropriate ones.
In 2009, Barber received the James Beard award for America's Outstanding Chef, and was named one of the world's most influential people in Time’s annual "Time 100" list.
"Dan Barber is increasingly becoming known as a chef-thinker, popularizing simple ideas that upend the way people think about the food we eat."
http://www.ted.com/talks/dan_barber_how_i_fell_in_love_with_a_fish.html
Chef Dan Barber squares off with a dilemma facing many chefs today: how to keep fish on the menu. With impeccable research and deadpan humor, he chronicles his pursuit of a sustainable fish he could love, and the foodie's honeymoon he's enjoyed since discovering an outrageously delicious fish raised using a revolutionary farming method in Spain.
Dan Barber is the chef at New York's Blue Hill restaurant, and Blue Hill at Stone Barns in Westchester, where he practices a kind of close-to-the-land cooking married to agriculture and stewardship of the earth. As described on Chez Pim: "Stone Barns is only 45 minutes from Manhattan, but it might as well be a whole different universe. A model of self-sufficiency and environmental responsibility, Stone Barns is a working farm, ranch, and a three-Michelin-star-worthy restaurant." It's a vision of a new kind of food chain.
Barber's philosophy of food focuses on pleasure and thoughtful conservation -- on knowing where the food on your plate comes from and the unseen forces that drive what we eat. He's written on US agricultural policies, asking for a new vision that does not throw the food chain out of balance by subsidizing certain crops at the expense of more appropriate ones.
In 2009, Barber received the James Beard award for America's Outstanding Chef, and was named one of the world's most influential people in Time’s annual "Time 100" list.
"Dan Barber is increasingly becoming known as a chef-thinker, popularizing simple ideas that upend the way people think about the food we eat."
Sunday, March 14, 2010
Glacial / interglacial variations in atmospheric carbon dioxide
http://www.up.ethz.ch/education/biogeochem_cycles/reading_list/sigman_nat_00.pdf
Glacial/interglacial variations in atmospheric carbon dioxide
Daniel M. Sigman* & Edward A. Boyle²
* Department of Geosciences, Guyot Hall, Princeton University, Princeton, New Jersey 08544, USA
² Department of Earth, Atmospheric, and Planetary Sciences, Room E34-258, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Massachusetts 02139,
USA
Twenty years ago, measurements on ice cores showed that the concentration of carbon dioxide in the atmosphere was lower during ice ages than it is today. As yet, there is no broadly accepted explanation for this difference. Current investigations focus on the ocean's `biological pump', the sequestration of carbon in the ocean interior by the rain of organic carbon out of the surface ocean, and its effect on the burial of calcium carbonate in marine sediments. Some researchers surmise that the whole-ocean reservoir of algal nutrients was larger during glacial times, strengthening the biological pump at low latitudes, where these nutrients are currently limiting. Others propose that the biological pump was more efficient during glacial times because of more complete utilization of nutrients at high latitudes, where much of the nutrient supply currently goes unused. We present a version of the latter hypothesis that focuses on the open ocean surrounding Antarctica, involving both the biology and physics of that region.
Pg 8 -
In the subantarctic, planktonic foraminiferal Cd/Ca and the 13C/12C of diatom-bound organic matter both show changes that are consistent with an ice age state of higher nutrient utilization62,82.
Fig 6 on page 9 gives a very clear depiction of the Dissolved Oxygen levels of surface water in present day oceans and during the last glacial period.
Glacial/interglacial variations in atmospheric carbon dioxide
Daniel M. Sigman* & Edward A. Boyle²
* Department of Geosciences, Guyot Hall, Princeton University, Princeton, New Jersey 08544, USA
² Department of Earth, Atmospheric, and Planetary Sciences, Room E34-258, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Massachusetts 02139,
USA
Twenty years ago, measurements on ice cores showed that the concentration of carbon dioxide in the atmosphere was lower during ice ages than it is today. As yet, there is no broadly accepted explanation for this difference. Current investigations focus on the ocean's `biological pump', the sequestration of carbon in the ocean interior by the rain of organic carbon out of the surface ocean, and its effect on the burial of calcium carbonate in marine sediments. Some researchers surmise that the whole-ocean reservoir of algal nutrients was larger during glacial times, strengthening the biological pump at low latitudes, where these nutrients are currently limiting. Others propose that the biological pump was more efficient during glacial times because of more complete utilization of nutrients at high latitudes, where much of the nutrient supply currently goes unused. We present a version of the latter hypothesis that focuses on the open ocean surrounding Antarctica, involving both the biology and physics of that region.
Pg 8 -
In the subantarctic, planktonic foraminiferal Cd/Ca and the 13C/12C of diatom-bound organic matter both show changes that are consistent with an ice age state of higher nutrient utilization62,82.
Fig 6 on page 9 gives a very clear depiction of the Dissolved Oxygen levels of surface water in present day oceans and during the last glacial period.
Friday, March 12, 2010
Charles 'Mac' Mathias, founder of Chesapeake Bay cleanup effort, dies
http://wjz.com/local/algae.bill.chesapeake.2.1557656.html
Charles 'Mac' Mathias, founder of Bay cleanup effort, dies
By Karl Blankenship
Charles McC. Mathias Jr., a three-term United States senator from Maryland who was instrumental in launching the Chesapeake Bay restoration effort, died Jan. 25 at his home in Chevy Chase, MD, of complications from Parkinson's Disease. He was 87.
Mathias, who served in the U.S. House from 1961 through 1969, then in the Senate until 1987, was a liberal Republican who sponsored civil rights legislation, advocated for equal rights for women and was critical of the Vietnam War. He was called "the conscience of the Senate" by its Democratic leader, Mike Mansfield.
Mathias also played a pivotal role in Chesapeake restoration, even though he grew up far from the Bay in western Maryland. Sen. Barbara Mikulski, who was elected to Mathias' seat after his retirement, hailed him as "the founding father of a great and ongoing effort to save the Chesapeake."
As a first-term senator, Mathias heard a growing number of complaints from Marylanders about the Bay's condition and its poor water quality. "I remember when I was a small child, the Chesapeake Bay was pretty clear," he recalled in 2003 interview with the Bay Journal. "Now it looked just muddy."
In 1973, "Mac" as he was commonly known, took a a five-day, 450-mile tour of the Chesapeake Bay for a firsthand look at problems facing the Bay.
Then-EPA Administrator Russell Train was along for part of the trip, as was Interior Secretary Rogers Morton. Along the way, Mathias talked to more than 150 people, from businessmen to government officials to watermen to farmers to scientists. "Everyone we met was interested and wanted to be a part of it," he said. "The spirit of the time was tremendous."
The boat trip, Mathias said, gave him a sense of the diverse problems facing the Bay, from discharge pipes leading out of cities, to runoff from rural areas, to the loss of underwater grass beds almost everywhere. "By pulling all of these things together, you got a comprehensive picture of what all the problems of the Bay were," he said. "They were not just one thing."
After the trip, Mathias pushed for increased attention on the Bay, which ultimately resulted in a five-year, $25 million study by the EPA. The state-federal Chesapeake Bay Program was created in 1983 in response to the findings of that study.
Two decades after the Bay Program was started, though, he said he was not surprised the task of restoring the Chesapeake was still under way. "I had hoped it could be completed long before this, but in a way there is no completion," he said. "It is an ongoing problem because of the difficulties that feed the problem."
"The fact there are thousands of homes being built ultimately ends in a greater burden on the Bay from all kinds of pollution," he said. "We are beginning to realize that it has to be an ongoing project. As long as there are human activities in the Bay there are going to have to be offsetting programs to deal with them."
Nonetheless, he said, "I think we've come a long way." And, he said, other politicians should follow his lead by taking a trip like his to appreciate the diversity of issues afflicting the nation's largest estuary. "I would recommend it."
Charles 'Mac' Mathias, founder of Bay cleanup effort, dies
By Karl Blankenship
Charles McC. Mathias Jr., a three-term United States senator from Maryland who was instrumental in launching the Chesapeake Bay restoration effort, died Jan. 25 at his home in Chevy Chase, MD, of complications from Parkinson's Disease. He was 87.
Mathias, who served in the U.S. House from 1961 through 1969, then in the Senate until 1987, was a liberal Republican who sponsored civil rights legislation, advocated for equal rights for women and was critical of the Vietnam War. He was called "the conscience of the Senate" by its Democratic leader, Mike Mansfield.
Mathias also played a pivotal role in Chesapeake restoration, even though he grew up far from the Bay in western Maryland. Sen. Barbara Mikulski, who was elected to Mathias' seat after his retirement, hailed him as "the founding father of a great and ongoing effort to save the Chesapeake."
As a first-term senator, Mathias heard a growing number of complaints from Marylanders about the Bay's condition and its poor water quality. "I remember when I was a small child, the Chesapeake Bay was pretty clear," he recalled in 2003 interview with the Bay Journal. "Now it looked just muddy."
In 1973, "Mac" as he was commonly known, took a a five-day, 450-mile tour of the Chesapeake Bay for a firsthand look at problems facing the Bay.
Then-EPA Administrator Russell Train was along for part of the trip, as was Interior Secretary Rogers Morton. Along the way, Mathias talked to more than 150 people, from businessmen to government officials to watermen to farmers to scientists. "Everyone we met was interested and wanted to be a part of it," he said. "The spirit of the time was tremendous."
The boat trip, Mathias said, gave him a sense of the diverse problems facing the Bay, from discharge pipes leading out of cities, to runoff from rural areas, to the loss of underwater grass beds almost everywhere. "By pulling all of these things together, you got a comprehensive picture of what all the problems of the Bay were," he said. "They were not just one thing."
After the trip, Mathias pushed for increased attention on the Bay, which ultimately resulted in a five-year, $25 million study by the EPA. The state-federal Chesapeake Bay Program was created in 1983 in response to the findings of that study.
Two decades after the Bay Program was started, though, he said he was not surprised the task of restoring the Chesapeake was still under way. "I had hoped it could be completed long before this, but in a way there is no completion," he said. "It is an ongoing problem because of the difficulties that feed the problem."
"The fact there are thousands of homes being built ultimately ends in a greater burden on the Bay from all kinds of pollution," he said. "We are beginning to realize that it has to be an ongoing project. As long as there are human activities in the Bay there are going to have to be offsetting programs to deal with them."
Nonetheless, he said, "I think we've come a long way." And, he said, other politicians should follow his lead by taking a trip like his to appreciate the diversity of issues afflicting the nation's largest estuary. "I would recommend it."
Wednesday, March 10, 2010
Role of Increased Marine Silica Input on Paleo-pCO2 Levels
http://www.agu.org/journals/pa/v015/i003/1999PA000427/
PALEOCEANOGRAPHY, VOL. 15, NO. 3, PAGES 292–298, 2000
Role of Increased Marine Silica Input on Paleo-pCO2 Levels
Kevin G. Harrison
Geology and Geophysics Department, Boston College, Chestnut Hill, Massachusetts
Abstract
Changing the supply of silica to the ocean may alter pCO2 levels. The increase in dust delivered to the ocean during glacial times increased the availability of silica for biological uptake. The increased silica levels shifted species composition: Diatom populations increased and coccolith populations decreased. Decreasing the population of coccoliths decreased the flux of calcite to the sediments, which, in turn, lowered pCO2 levels enough to explain the glacial-interglacial pCO2 transition. Furthermore, the contemporary increase in dust delivered to the ocean’s mixed layer may be removing significant amounts of carbon dioxide from the atmosphere at present. To set the stage, this silica hypothesis is compared with the iron fertilization and nitrogen fixation hypotheses.
---------------
Silica flow into oceans has decreased in 20th Century and has not increased, this is one of the causes of Dead Zones in estuaries and coastal waters and for fish kills and harmful algal blooms in lakes and rivers.
The reduction is silica is both actual and in proportion to N and P flow.
Dams reduce the amount of silt flowing down rivers and higher agricultural activity results in higher N and P flow down rivers.
Its well documented that in River Mississippi Si : N ratio was 3 : 1 fifty years ago and not its < 1 : 1. This has resulted in the Gulf of Mexico Dead Zone.
PALEOCEANOGRAPHY, VOL. 15, NO. 3, PAGES 292–298, 2000
Role of Increased Marine Silica Input on Paleo-pCO2 Levels
Kevin G. Harrison
Geology and Geophysics Department, Boston College, Chestnut Hill, Massachusetts
Abstract
Changing the supply of silica to the ocean may alter pCO2 levels. The increase in dust delivered to the ocean during glacial times increased the availability of silica for biological uptake. The increased silica levels shifted species composition: Diatom populations increased and coccolith populations decreased. Decreasing the population of coccoliths decreased the flux of calcite to the sediments, which, in turn, lowered pCO2 levels enough to explain the glacial-interglacial pCO2 transition. Furthermore, the contemporary increase in dust delivered to the ocean’s mixed layer may be removing significant amounts of carbon dioxide from the atmosphere at present. To set the stage, this silica hypothesis is compared with the iron fertilization and nitrogen fixation hypotheses.
---------------
Silica flow into oceans has decreased in 20th Century and has not increased, this is one of the causes of Dead Zones in estuaries and coastal waters and for fish kills and harmful algal blooms in lakes and rivers.
The reduction is silica is both actual and in proportion to N and P flow.
Dams reduce the amount of silt flowing down rivers and higher agricultural activity results in higher N and P flow down rivers.
Its well documented that in River Mississippi Si : N ratio was 3 : 1 fifty years ago and not its < 1 : 1. This has resulted in the Gulf of Mexico Dead Zone.
Tuesday, March 9, 2010
Tests show algae [Red Tide] may affect Massachusetts sooner than usual
US issues red tide warning
Tests show algae may affect Massachusetts sooner than usual
By Victor Tine
Staff writer
NEWBURYPORT — Local clammers will be watching the wind this summer.
The National Oceanic and Atmospheric Administration has issued a warning that the poisonous algae known as red tide could cause significant problems in New England shellfish beds, starting this spring.
NOAA scientists based their warning on a sea floor survey in the Gulf of Maine that found a substantial increase in the number of seed-like cysts of an organism that causes blooms of red tide, which causes an illness called paralytic shellfish poisoning.
The name red tide comes from the reddish-brown tint that colors waters with a large algae presence.
Red tide algae is ingested by filter feeders, such as clams and mussels. The algae causes no harm to the shellfish, but can cause paralysis in humans who eat them.
While NOAA declined to predict where and when the red tide would appear, the scientists found that the cysts' presence appears to have expanded southward, which means the red tide could affect Massachusetts Bay sooner than it has in the past.
Cysts are deposited in the fall and hatch the following spring.
"Last fall, the abundance of cysts in the sediment was 60 percent higher than observed prior to the historic bloom of 2005, indicating that a large bloom is likely in the spring of 2010," NOAA said in a prepared statement.
"Our research has shown that cyst abundance in the fall is an indicator of the magnitude of the bloom the following year," said Dennis McGillicuddy, a senior scientist at the Woods Hole Oceanographic Institution.
Jeff Kennedy of the state's Marine Fisheries Division said the cyst beds extend south and east from roughly around Portsmouth, N.H.
"They're in closer proximity than we've ever seen it before, at least since we've been monitoring," he said.
The density of the cysts is also a cause for concern, he said.
But as Newbury shellfish constable Charles Colby observed, "It all depends on which way the wind blows."
Colby said the red tide algae float on top of the water. If the prevailing wind is from the west, as it usually is, the algae bloom will stay offshore where it won't affect the local shellfish beds, he said.
If the red tide does come ashore, clammers will have no choice but to stop harvesting, Colby said.
"There are no options," he said.
Kennedy said the Marine Fisheries Division monitors shellfish beds weekly, more frequently as algae levels rise, and close the areas when red tide reaches toxic levels.
He said the 2005 red tide bloom was the worst in recent memory. It closed Massachusetts shellfish beds from the New Hampshire border to Cape Cod for about two months.
Typically, a bloom on the North Shore will last about two weeks, he said.
Dishes containing shellfish are staples on the menus of a number of Newburyport-area restaurants, and NOAA said in its statement that restaurateurs may want to make plans for alternate supplies.
Gary Greco, owner of the Starboard Galley on Water Street, said that previous red tide outbreaks haven't affected supplies but can impact prices.
"Usually it just shifts," he said. "If I can't get them from Maine, I get them from Maryland."
Greco said he gets all his seafood from David's Fish Market in Salisbury, where owner Gordon Blaney confirmed that a red tide bloom leaves him with two choices, stop carrying clams or find another supply.
"We'd love to have good, wholesome stuff from our own area, but if we can't, we look elsewhere for the product," he said.
That usually means paying higher prices, Blaney said.
"It doesn't matter if it's oranges freezing in Florida or red tide in clams in Massachusetts, when a normal supply is disrupted, it affects the price," he said. "It's just supply and demand."
Tests show algae may affect Massachusetts sooner than usual
By Victor Tine
Staff writer
NEWBURYPORT — Local clammers will be watching the wind this summer.
The National Oceanic and Atmospheric Administration has issued a warning that the poisonous algae known as red tide could cause significant problems in New England shellfish beds, starting this spring.
NOAA scientists based their warning on a sea floor survey in the Gulf of Maine that found a substantial increase in the number of seed-like cysts of an organism that causes blooms of red tide, which causes an illness called paralytic shellfish poisoning.
The name red tide comes from the reddish-brown tint that colors waters with a large algae presence.
Red tide algae is ingested by filter feeders, such as clams and mussels. The algae causes no harm to the shellfish, but can cause paralysis in humans who eat them.
While NOAA declined to predict where and when the red tide would appear, the scientists found that the cysts' presence appears to have expanded southward, which means the red tide could affect Massachusetts Bay sooner than it has in the past.
Cysts are deposited in the fall and hatch the following spring.
"Last fall, the abundance of cysts in the sediment was 60 percent higher than observed prior to the historic bloom of 2005, indicating that a large bloom is likely in the spring of 2010," NOAA said in a prepared statement.
"Our research has shown that cyst abundance in the fall is an indicator of the magnitude of the bloom the following year," said Dennis McGillicuddy, a senior scientist at the Woods Hole Oceanographic Institution.
Jeff Kennedy of the state's Marine Fisheries Division said the cyst beds extend south and east from roughly around Portsmouth, N.H.
"They're in closer proximity than we've ever seen it before, at least since we've been monitoring," he said.
The density of the cysts is also a cause for concern, he said.
But as Newbury shellfish constable Charles Colby observed, "It all depends on which way the wind blows."
Colby said the red tide algae float on top of the water. If the prevailing wind is from the west, as it usually is, the algae bloom will stay offshore where it won't affect the local shellfish beds, he said.
If the red tide does come ashore, clammers will have no choice but to stop harvesting, Colby said.
"There are no options," he said.
Kennedy said the Marine Fisheries Division monitors shellfish beds weekly, more frequently as algae levels rise, and close the areas when red tide reaches toxic levels.
He said the 2005 red tide bloom was the worst in recent memory. It closed Massachusetts shellfish beds from the New Hampshire border to Cape Cod for about two months.
Typically, a bloom on the North Shore will last about two weeks, he said.
Dishes containing shellfish are staples on the menus of a number of Newburyport-area restaurants, and NOAA said in its statement that restaurateurs may want to make plans for alternate supplies.
Gary Greco, owner of the Starboard Galley on Water Street, said that previous red tide outbreaks haven't affected supplies but can impact prices.
"Usually it just shifts," he said. "If I can't get them from Maine, I get them from Maryland."
Greco said he gets all his seafood from David's Fish Market in Salisbury, where owner Gordon Blaney confirmed that a red tide bloom leaves him with two choices, stop carrying clams or find another supply.
"We'd love to have good, wholesome stuff from our own area, but if we can't, we look elsewhere for the product," he said.
That usually means paying higher prices, Blaney said.
"It doesn't matter if it's oranges freezing in Florida or red tide in clams in Massachusetts, when a normal supply is disrupted, it affects the price," he said. "It's just supply and demand."
Phytoplankton Bloom in the Arabian Sea
http://earthobservatory.nasa.gov/IOTD/view.php?id=43050&src=eoa-iotd
Phytoplankton Bloom in the Arabian Sea
Posted March 8, 2010
Phytoplankton swirled across the Arabian Sea on February 18, 2010, drawn into thin green ribbons by turbulent eddies. The bloom stretches from the shores of Pakistan (top) to the coast of Oman (lower left). The washed out appearance at the upper left of the image is due to sunglint, which is the mirror–like reflection of sunlight off the water. Some of the brightness may be caused by blowing dust. Pakistan’s coastal waters are tinged blue as well as green. The color may result from numerous influences, including phytoplankton and sediment.
The phytoplankton blooms in the northern Arabian Sea are strongly influenced by the seasonal wind shifts (the monsoon) that dominate the area’s climate. Because the Arabian Sea is landlocked to the north, it is less influenced by large-scale ocean circulation and more strongly influenced by the monsoon winds. Large blooms of phytoplankton occur in the summer, when strong southwesterly winds blow from the ocean toward land, mixing the water. Blooms also happen in the winter, however, when northeast winds blow offshore.
In the past few years, a team of oceanographers studying the Arabian Sea has noticed that kinds of phytoplankton present during the Northeast (winter) Monsoon seem to be changing. Among the changes is the increasingly frequent and widespread appearance of a dinoflagellate species called Noctiluca miliaris. Prior to the late 1990s, this type of phytoplankton showed up only sporadically during summer blooms, usually in conjunction with the upwelling of low-oxygen waters. According to the researchers, the unusual abundance of this organism in winter blooms may be a sign that the waters of the Arabian Sea are becoming more eutrophic—overly fertile and oxygen-depleted.
It generally isn’t possible to identify phytoplankton species through satellite observations alone, and many other kinds of phytoplankton occur in the area. However, the scientists’ description of the interloper—“N. miliaris tends to aggregate at the surface to form large, slimy green patches”— is certainly consistent with the bloom shown in this image. This natural-color image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite.
References
Gomes, H. D. R., Goes, J. I., Matondkar, S. P., Parab, S. G., Al-Azri, A. R., & Thoppil, P. G. (2008). Blooms of Noctiluca miliaris in the Arabian Sea—An in situ and satellite study. Deep Sea Research Part I: Oceanographic Research Papers, 55(6), 751-765.
Further Reading
Winds Connect Snow to Sea
What Are Phytoplankton?
NASA image by Norman Kuring, GSFC Oceancolor Team. Caption by Rebecca Lindsey and Norman Kuring.
Instrument: Aqua - MODIS
Phytoplankton Bloom in the Arabian Sea
Posted March 8, 2010
Phytoplankton swirled across the Arabian Sea on February 18, 2010, drawn into thin green ribbons by turbulent eddies. The bloom stretches from the shores of Pakistan (top) to the coast of Oman (lower left). The washed out appearance at the upper left of the image is due to sunglint, which is the mirror–like reflection of sunlight off the water. Some of the brightness may be caused by blowing dust. Pakistan’s coastal waters are tinged blue as well as green. The color may result from numerous influences, including phytoplankton and sediment.
The phytoplankton blooms in the northern Arabian Sea are strongly influenced by the seasonal wind shifts (the monsoon) that dominate the area’s climate. Because the Arabian Sea is landlocked to the north, it is less influenced by large-scale ocean circulation and more strongly influenced by the monsoon winds. Large blooms of phytoplankton occur in the summer, when strong southwesterly winds blow from the ocean toward land, mixing the water. Blooms also happen in the winter, however, when northeast winds blow offshore.
In the past few years, a team of oceanographers studying the Arabian Sea has noticed that kinds of phytoplankton present during the Northeast (winter) Monsoon seem to be changing. Among the changes is the increasingly frequent and widespread appearance of a dinoflagellate species called Noctiluca miliaris. Prior to the late 1990s, this type of phytoplankton showed up only sporadically during summer blooms, usually in conjunction with the upwelling of low-oxygen waters. According to the researchers, the unusual abundance of this organism in winter blooms may be a sign that the waters of the Arabian Sea are becoming more eutrophic—overly fertile and oxygen-depleted.
It generally isn’t possible to identify phytoplankton species through satellite observations alone, and many other kinds of phytoplankton occur in the area. However, the scientists’ description of the interloper—“N. miliaris tends to aggregate at the surface to form large, slimy green patches”— is certainly consistent with the bloom shown in this image. This natural-color image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite.
References
Gomes, H. D. R., Goes, J. I., Matondkar, S. P., Parab, S. G., Al-Azri, A. R., & Thoppil, P. G. (2008). Blooms of Noctiluca miliaris in the Arabian Sea—An in situ and satellite study. Deep Sea Research Part I: Oceanographic Research Papers, 55(6), 751-765.
Further Reading
Winds Connect Snow to Sea
What Are Phytoplankton?
NASA image by Norman Kuring, GSFC Oceancolor Team. Caption by Rebecca Lindsey and Norman Kuring.
Instrument: Aqua - MODIS
Sunday, March 7, 2010
The Global Biogeochemical Silicon Cycle
The Global Biogeochemical Silicon Cycle
Eric Struyf & Adriaan Smis & Stefan Van Damme &
Patrick Meire & Daniel J. Conley
http://www.springerlink.com/content/f40058279411v057/fulltext.pdf
Consequently, transport of continental DSi to the oceans is an important component
in oceanic primary production, a large part of which consists of diatoms [11]. Forty percent of all oceanic C sequestration (∼1.5–2.8 Gton C yr−1) can be attributed to the growth and sedimentation of diatoms [12, 13]. Although primary production through different groups of marine phytoplankton also results in a net CO2 flux towards the sea bottom (the “biological carbon pump”) [14], a crucial difference exists between diatoms and coccolithophores, an important subgroup of non-siliceous phytoplankton. Coccolithophores are characterized by calcite shells (=coccoliths); CO2 is produced
when calcium reacts with hydrogen carbonate during calcite formation (the “carbonate counter pump”) [15].
Therefore, an increased dominance of coccolithophores decreases the net sequestration of CO2 and consequently the flux of CO2 from the atmosphere towards the ocean floor
[11]. The biological carbon pump in the ocean is often referred to as the “biological Si pump” [7]. Changes in Si inputs to marine ecosystems, especially in the coastal ocean, can significantly influence the species composition of oceanic primary producers, especially the balance of production between diatoms and non-siliceous
phytoplankton [16]. It has been hypothesized that a higher contribution of diatoms to total oceanic phytoplankton biomass occurred during the Last Glacial Maximum (79%
vs. 54% today) as the result of increased eolian inputs of Si [11]. This demonstrates that a link exists between Si transport from terrestrial to oceanic systems, atmospheric CO2 concentrations and variations in global climate.
2.2 Silicon and Eutrophication of Coastal and Lake
Ecosystems Silicon plays an important role in the current eutrophication problems of numerous lacustrine, estuarine and coastal ecosystems [17, 18]. In most major rivers worldwide, concentrations of N and P have at least doubled as the result of anthropogenic inputs [19]. Whereas total algal growth is primarily regulated by the availability of N and P, the relative availability of Si and the availability of Si
relative to N and P, e.g. the Si:N and Si:P ratios, can influence the composition of the phytoplankton community [18]. The lack of Si can change aquatic ecosystems from
those dominated by diatoms to non-diatom based aquatic ecosystems usually dominated by flagellates [20]. Based on an evaluation of long-term algal blooms and nutrient
conditions in different regions, it can be concluded that decreased Si:N and Si:P ratios can give rise to Si limitation of diatoms and the reduction of diatoms in the phytoplankton community. In addition, subsequent non-diatom blooms can contain harmful algal species such as Phaeocystis sp., Gonyaulax sp., Chrysochromulina sp. [21].
Diatoms are the primary energetic source for estuarine and coastal food chains [22]. Transfer of energy to higher trophic levels is enhanced by diatoms through their higher nutritional value [23] and the limited amount of trophic steps between diatoms and higher trophic levels [24]. Nondiatom species are known to be less available to higher trophic levels [21, 25] and some non-diatom based food webs are economically undesirable [20]. Therefore, the proportion of diatoms in the phytoplankton community is of primary importance for many fisheries globally [20].
Furthermore, DSi limitation of diatoms and resultant blooms dominated by non-diatom species can result in anoxic conditions, increased water turbidity and excessive
production of toxic components [26].
Increases in diatom biomass as a result of higher N and P inputs results in increased diatom sinking rates and increased diatom burial in bottom sediments [27]. Consequently, in anthropogenically eutrophied systems that have experienced increases in N and P loading from human activities with sufficiently long hydrodynamic residence times, the aquatic DSi stock decreases and eutrophication problems are worsened [18]. A similar effect has been described for dams, e.g. the artificial lake effect [28]. Dams increase the residence time of water in river ecosystems, which stimulates phytoplankton productivity [29]. This results in the increased trapping of biogenic Si in lake sediments, and decreased transport of DSi downstream. This effect has been described for major dams worldwide, and is an important component of changed N:P:Si ratio’s in coastal ecosystems.
Eric Struyf & Adriaan Smis & Stefan Van Damme &
Patrick Meire & Daniel J. Conley
http://www.springerlink.com/content/f40058279411v057/fulltext.pdf
Consequently, transport of continental DSi to the oceans is an important component
in oceanic primary production, a large part of which consists of diatoms [11]. Forty percent of all oceanic C sequestration (∼1.5–2.8 Gton C yr−1) can be attributed to the growth and sedimentation of diatoms [12, 13]. Although primary production through different groups of marine phytoplankton also results in a net CO2 flux towards the sea bottom (the “biological carbon pump”) [14], a crucial difference exists between diatoms and coccolithophores, an important subgroup of non-siliceous phytoplankton. Coccolithophores are characterized by calcite shells (=coccoliths); CO2 is produced
when calcium reacts with hydrogen carbonate during calcite formation (the “carbonate counter pump”) [15].
Therefore, an increased dominance of coccolithophores decreases the net sequestration of CO2 and consequently the flux of CO2 from the atmosphere towards the ocean floor
[11]. The biological carbon pump in the ocean is often referred to as the “biological Si pump” [7]. Changes in Si inputs to marine ecosystems, especially in the coastal ocean, can significantly influence the species composition of oceanic primary producers, especially the balance of production between diatoms and non-siliceous
phytoplankton [16]. It has been hypothesized that a higher contribution of diatoms to total oceanic phytoplankton biomass occurred during the Last Glacial Maximum (79%
vs. 54% today) as the result of increased eolian inputs of Si [11]. This demonstrates that a link exists between Si transport from terrestrial to oceanic systems, atmospheric CO2 concentrations and variations in global climate.
2.2 Silicon and Eutrophication of Coastal and Lake
Ecosystems Silicon plays an important role in the current eutrophication problems of numerous lacustrine, estuarine and coastal ecosystems [17, 18]. In most major rivers worldwide, concentrations of N and P have at least doubled as the result of anthropogenic inputs [19]. Whereas total algal growth is primarily regulated by the availability of N and P, the relative availability of Si and the availability of Si
relative to N and P, e.g. the Si:N and Si:P ratios, can influence the composition of the phytoplankton community [18]. The lack of Si can change aquatic ecosystems from
those dominated by diatoms to non-diatom based aquatic ecosystems usually dominated by flagellates [20]. Based on an evaluation of long-term algal blooms and nutrient
conditions in different regions, it can be concluded that decreased Si:N and Si:P ratios can give rise to Si limitation of diatoms and the reduction of diatoms in the phytoplankton community. In addition, subsequent non-diatom blooms can contain harmful algal species such as Phaeocystis sp., Gonyaulax sp., Chrysochromulina sp. [21].
Diatoms are the primary energetic source for estuarine and coastal food chains [22]. Transfer of energy to higher trophic levels is enhanced by diatoms through their higher nutritional value [23] and the limited amount of trophic steps between diatoms and higher trophic levels [24]. Nondiatom species are known to be less available to higher trophic levels [21, 25] and some non-diatom based food webs are economically undesirable [20]. Therefore, the proportion of diatoms in the phytoplankton community is of primary importance for many fisheries globally [20].
Furthermore, DSi limitation of diatoms and resultant blooms dominated by non-diatom species can result in anoxic conditions, increased water turbidity and excessive
production of toxic components [26].
Increases in diatom biomass as a result of higher N and P inputs results in increased diatom sinking rates and increased diatom burial in bottom sediments [27]. Consequently, in anthropogenically eutrophied systems that have experienced increases in N and P loading from human activities with sufficiently long hydrodynamic residence times, the aquatic DSi stock decreases and eutrophication problems are worsened [18]. A similar effect has been described for dams, e.g. the artificial lake effect [28]. Dams increase the residence time of water in river ecosystems, which stimulates phytoplankton productivity [29]. This results in the increased trapping of biogenic Si in lake sediments, and decreased transport of DSi downstream. This effect has been described for major dams worldwide, and is an important component of changed N:P:Si ratio’s in coastal ecosystems.
Modification of the biogeochemical cycle of silica with eutrophication
Modification of the biogeochemical cycle of silica with eutrophication
Daniel J. Conley, Claire L. schelske, Eugene F. stoermer
Vol. 101: 179-192, 1993 MARINE ECOLOGY PROGRESS SERIES Mar. Ecol. Prog. Ser.
http://www.int-res.com/articles/meps/101/m101p179.pdf
ABSTRACT- Nutrient enrichment and consequent alteration of nutrient biogeochernical cycles is a serious problem in both freshwater and marine systems. The response of aquatic systems to additions of N and P is generally to increase algal biomass. The partitioning of these nutrients into different functional groups of autotrophic organisms is dependent upon both intrinsic and extrinsic factors.
A common response to nutrient loading in northern temperate aquatic ecosystems is an increase in diatom biomass. Because nutrient enrichment generally leads to increases in water column concentrations of total N and total P (and not Si) such nutrient loading can lead to transient nutrient limitation of diatom biomass due to lack of dissolved silicate (DSi). Increased production of diatom biomass can lead to an increased accumulation of biogenic silica in sediments, ultimately resulting in a decline in the water column reservoir of DSi. Such biogeochemical changes in the silica cycle induced by eutrophication were first reported for the North American Laurentian Great Lakes. However, these changes are not a regional problem confined to the Great Lakes, but occur in many freshwater and marine systems throughout the world. Here we summarize the effects of anthropogenic modification of silica biogeochemical cycles for the North American Laurentian Great Lakes, describe some of the biogeochemical changes occurring in other systems, and discuss some of the ecological implications of a reduction in water column DSi concentrations, including changes in species composition, as DSi concentrations become limiting to diatom growth and biomass, changes in food web dynamics, and altered nutnent-recycling processes.
...
Pg 11
"Man cannot alter the inputs of DSi to aquatic ecosystems to any significant extent; they are essentially uncontrollable and result from weathering reactions in the watershed."
This is no longer true.
NUALGI is a cost effective means to provide Silica to diatoms.
Daniel J. Conley, Claire L. schelske, Eugene F. stoermer
Vol. 101: 179-192, 1993 MARINE ECOLOGY PROGRESS SERIES Mar. Ecol. Prog. Ser.
http://www.int-res.com/articles/meps/101/m101p179.pdf
ABSTRACT- Nutrient enrichment and consequent alteration of nutrient biogeochernical cycles is a serious problem in both freshwater and marine systems. The response of aquatic systems to additions of N and P is generally to increase algal biomass. The partitioning of these nutrients into different functional groups of autotrophic organisms is dependent upon both intrinsic and extrinsic factors.
A common response to nutrient loading in northern temperate aquatic ecosystems is an increase in diatom biomass. Because nutrient enrichment generally leads to increases in water column concentrations of total N and total P (and not Si) such nutrient loading can lead to transient nutrient limitation of diatom biomass due to lack of dissolved silicate (DSi). Increased production of diatom biomass can lead to an increased accumulation of biogenic silica in sediments, ultimately resulting in a decline in the water column reservoir of DSi. Such biogeochemical changes in the silica cycle induced by eutrophication were first reported for the North American Laurentian Great Lakes. However, these changes are not a regional problem confined to the Great Lakes, but occur in many freshwater and marine systems throughout the world. Here we summarize the effects of anthropogenic modification of silica biogeochemical cycles for the North American Laurentian Great Lakes, describe some of the biogeochemical changes occurring in other systems, and discuss some of the ecological implications of a reduction in water column DSi concentrations, including changes in species composition, as DSi concentrations become limiting to diatom growth and biomass, changes in food web dynamics, and altered nutnent-recycling processes.
...
Pg 11
"Man cannot alter the inputs of DSi to aquatic ecosystems to any significant extent; they are essentially uncontrollable and result from weathering reactions in the watershed."
This is no longer true.
NUALGI is a cost effective means to provide Silica to diatoms.
Friday, March 5, 2010
World's Largest Dead Zone Suffocating Sea
http://news.nationalgeographic.com/news/2010/02/100305-baltic-sea-algae-dead-zones-water/
James Owen in Stockholm
for National Geographic News
Published March 5, 2010
This story is part of a special series that explores the global water crisis. For more clean water news, photos, and information, visit National Geographic's Freshwater Web site.
"Eagle!" The shout goes up as a great shadow sweeps over our boat. The white-tailed eagle makes its descent to one of the 24,000 islands that make up Sweden's pine-covered, rocky Stockholm Archipelago.
The tourists on board for this nature tour in August 2009 mostly miss the photo opp. But local wildlife expert Peter Westman, of the conservation group WWF Sweden, assures the group that there will be others.
Numbers of this once-threatened predator have soared from 1,000 to more than 23,000 in the Baltic Sea (map) since pollutants including DDT, an eggshell-thinning pesticide, and PCBs, chemical compounds used in electrical equipment, were banned in the 1970s, Westman said.
But there is a new danger to the eagle and many other marine species: An explosion of microscopic algae called phytoplankton has inundated the Baltic's sensitive waters, sucking up oxygen and choking aquatic life.
Though a natural phenomenon at a smaller scale, these blooms have recently mushroomed at an alarming rate, fed by nutrients such as phosphorous and nitrogen from agricultural fertilizers and sewage. When it rains, farm fertilizers are washed into the sea. Sewage-treatment facilities also discharge waste into the Baltic ecosystem.
As a result, the Baltic is now home to seven of the of the world's ten largest marine "dead zones"—areas where the sea's oxygen has been used up by seabed bacteria that decompose the raining mass of dead algae.
"We’ve had enormous algal blooms here the last few years which have affected the whole ecosystem," Westman said.
Overfishing Adding to Algal Blooms
Overfishing of Baltic cod has greatly intensified the problem, Westman said. Cod eat sprats, a small, herring-like species that eat microscopic marine creatures called zooplankton that in turn eat the algae.
(Related: "Overfishing is Emptying World's Rivers, Lakes, Experts Warn.")
So, fewer cod and an explosion of zooplankton-eating sprats means more algae and less oxygen.
This vicious cycle gets worse as the spreading dead zones engulf the cod’s deep-water breeding grounds, he added.
The algal blooms, which can be toxic to animals and human swimmers, leave behind an ugly layer of green scum that fouls tourist beaches and starves seaweeds of light.
"Other species have taken the place [of cod], which don’t provide as good habitats for fish," especially juveniles, Westman said. "In the past couple of years common fishes like pike and perch have had virtually no reproduction in the inner part of the archipelago."
This vicious circle gets worse as the spreading algal blooms engulf the cod’s breeding grounds.
Too Late to Save the Baltic Sea?
Back in Stockholm, it's World Water Week, the annual global meeting on water issues organized by the Stockholm International Water Institute. On a conference room wall is a satellite image of the Baltic Sea, its deep blue edges giving way to a swirling, milky center that shows the algal blooms.
World Water Week attendees are pushing a new action plan called the Baltic Sea Strategy. The European Union-led initiative will attempt to coordinate the efforts of the eight EU members within the nine Baltic states—not including Russia—to revitalize their shared sea.
While the speakers all agree "it’s time for action," they don’t sound optimistic.
"It might well be too late," said Søren Nors Nielsen of the University of Copenhagen.
The planet’s youngest sea at less than 10,000 years old, the Baltic is unique in that it formed after the last ice age. It's also one of the world’s largest bodies of brackish water.
"Experience tells us such a system is almost impossible to predict," Nielsen said.
The Baltic Sea's unusual mix of fresh water and marine species means it's also especially vulnerable to environmental changes. "Evolution didn’t have time to develop an ecosystem able to tolerate flux," Nielsen explained.
(Related: "Viking Shipwrecks Face Ruin as Odd 'Worms' Invade.")
"Sea of Laws"
Water-law attorney Megan Walline of the Stockholm International Water Institute, who spoke at the Baltic Sea presentation, said there's already "a sea of laws" for dealing with human activities that threaten the Baltic.
Too numerous to list, they include existing EU directives that cover nutrient pollution and illegal fishing. The laws are there, they just need to be implemented, she said.
For his part, WWF’s Westman hopes the new EU strategy will at least turn the Baltic into "a kind of test area for enforcing and implementing the directives." For instance, the plan calls for phasing out phosphates in laundry and kitchen detergents, and putting in place more sustainable fishing regulations.
Even so, "There are no quick fixes, unfortunately," Westman concludes, reaching for his binoculars.
Seems it’s back to the eagles for now.
James Owen in Stockholm
for National Geographic News
Published March 5, 2010
This story is part of a special series that explores the global water crisis. For more clean water news, photos, and information, visit National Geographic's Freshwater Web site.
"Eagle!" The shout goes up as a great shadow sweeps over our boat. The white-tailed eagle makes its descent to one of the 24,000 islands that make up Sweden's pine-covered, rocky Stockholm Archipelago.
The tourists on board for this nature tour in August 2009 mostly miss the photo opp. But local wildlife expert Peter Westman, of the conservation group WWF Sweden, assures the group that there will be others.
Numbers of this once-threatened predator have soared from 1,000 to more than 23,000 in the Baltic Sea (map) since pollutants including DDT, an eggshell-thinning pesticide, and PCBs, chemical compounds used in electrical equipment, were banned in the 1970s, Westman said.
But there is a new danger to the eagle and many other marine species: An explosion of microscopic algae called phytoplankton has inundated the Baltic's sensitive waters, sucking up oxygen and choking aquatic life.
Though a natural phenomenon at a smaller scale, these blooms have recently mushroomed at an alarming rate, fed by nutrients such as phosphorous and nitrogen from agricultural fertilizers and sewage. When it rains, farm fertilizers are washed into the sea. Sewage-treatment facilities also discharge waste into the Baltic ecosystem.
As a result, the Baltic is now home to seven of the of the world's ten largest marine "dead zones"—areas where the sea's oxygen has been used up by seabed bacteria that decompose the raining mass of dead algae.
"We’ve had enormous algal blooms here the last few years which have affected the whole ecosystem," Westman said.
Overfishing Adding to Algal Blooms
Overfishing of Baltic cod has greatly intensified the problem, Westman said. Cod eat sprats, a small, herring-like species that eat microscopic marine creatures called zooplankton that in turn eat the algae.
(Related: "Overfishing is Emptying World's Rivers, Lakes, Experts Warn.")
So, fewer cod and an explosion of zooplankton-eating sprats means more algae and less oxygen.
This vicious cycle gets worse as the spreading dead zones engulf the cod’s deep-water breeding grounds, he added.
The algal blooms, which can be toxic to animals and human swimmers, leave behind an ugly layer of green scum that fouls tourist beaches and starves seaweeds of light.
"Other species have taken the place [of cod], which don’t provide as good habitats for fish," especially juveniles, Westman said. "In the past couple of years common fishes like pike and perch have had virtually no reproduction in the inner part of the archipelago."
This vicious circle gets worse as the spreading algal blooms engulf the cod’s breeding grounds.
Too Late to Save the Baltic Sea?
Back in Stockholm, it's World Water Week, the annual global meeting on water issues organized by the Stockholm International Water Institute. On a conference room wall is a satellite image of the Baltic Sea, its deep blue edges giving way to a swirling, milky center that shows the algal blooms.
World Water Week attendees are pushing a new action plan called the Baltic Sea Strategy. The European Union-led initiative will attempt to coordinate the efforts of the eight EU members within the nine Baltic states—not including Russia—to revitalize their shared sea.
While the speakers all agree "it’s time for action," they don’t sound optimistic.
"It might well be too late," said Søren Nors Nielsen of the University of Copenhagen.
The planet’s youngest sea at less than 10,000 years old, the Baltic is unique in that it formed after the last ice age. It's also one of the world’s largest bodies of brackish water.
"Experience tells us such a system is almost impossible to predict," Nielsen said.
The Baltic Sea's unusual mix of fresh water and marine species means it's also especially vulnerable to environmental changes. "Evolution didn’t have time to develop an ecosystem able to tolerate flux," Nielsen explained.
(Related: "Viking Shipwrecks Face Ruin as Odd 'Worms' Invade.")
"Sea of Laws"
Water-law attorney Megan Walline of the Stockholm International Water Institute, who spoke at the Baltic Sea presentation, said there's already "a sea of laws" for dealing with human activities that threaten the Baltic.
Too numerous to list, they include existing EU directives that cover nutrient pollution and illegal fishing. The laws are there, they just need to be implemented, she said.
For his part, WWF’s Westman hopes the new EU strategy will at least turn the Baltic into "a kind of test area for enforcing and implementing the directives." For instance, the plan calls for phasing out phosphates in laundry and kitchen detergents, and putting in place more sustainable fishing regulations.
Even so, "There are no quick fixes, unfortunately," Westman concludes, reaching for his binoculars.
Seems it’s back to the eagles for now.
Monday, March 1, 2010
Silicate as regulating nutrient in phytoplankton competition
http://www.int-res.com/articles/meps/83/m083p281.pdf
Vol. 83: 281-289, 1992
MARINE ECOLOGY PROGRESS SERIES
Published July 16
Silicate as regulating nutrient in phytoplankton competition
J. K. Egge, D. L. Aksnes
Department of Fisheries and Marine Biology. University of Bergen. Heyteknologisenteret, N-5020 Bergen. Norway
ABSTRACT- The development of phytoplankton communities was studied in floating enclosures. The enclosures were supplied with either surface water or water from 40 m depth. Nutrients with or without silicate were added in some of the experiments, while others received no artificial fertilization. It is shown that diatom dominance occurred irrespective of season if silicate concentration exceeded a threshold of approximately 2 PM. Flagellate dominance changed to diatom dominance within a few days after nutrient addition resulting in silicate concentrations above this threshold. Dominance of Phaeocystis sp. appeared on several occasions after the bloom of another species, but never at high silicate concentrations. The success of the diatom group seemed to be due to a high inherent growth rate at non-limiting silicate concentrations. Calculations indicated that the inherent growth rate for the diatom group had to be 5 to 50 % higher than for the flagellate group in order to explain the outcome of our experiments.
Vol. 83: 281-289, 1992
MARINE ECOLOGY PROGRESS SERIES
Published July 16
Silicate as regulating nutrient in phytoplankton competition
J. K. Egge, D. L. Aksnes
Department of Fisheries and Marine Biology. University of Bergen. Heyteknologisenteret, N-5020 Bergen. Norway
ABSTRACT- The development of phytoplankton communities was studied in floating enclosures. The enclosures were supplied with either surface water or water from 40 m depth. Nutrients with or without silicate were added in some of the experiments, while others received no artificial fertilization. It is shown that diatom dominance occurred irrespective of season if silicate concentration exceeded a threshold of approximately 2 PM. Flagellate dominance changed to diatom dominance within a few days after nutrient addition resulting in silicate concentrations above this threshold. Dominance of Phaeocystis sp. appeared on several occasions after the bloom of another species, but never at high silicate concentrations. The success of the diatom group seemed to be due to a high inherent growth rate at non-limiting silicate concentrations. Calculations indicated that the inherent growth rate for the diatom group had to be 5 to 50 % higher than for the flagellate group in order to explain the outcome of our experiments.
The possible importance of silicon in marine eutrophication
http://www.int-res.com/articles/meps/3/m003p083.pdf
Officer, C B., Ryther, J H (1980).
The possible importance of silicon in marine eutrophication.
Mar. Ecol. Prog. Ser 3: 83-91
Earth Sciences Department, Dartmouth College, Hanover, New Hampshire 03755, USA
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
ABSTRACT: Diatom phytoplankton populations are the usual food for zooplankton and filter feeding fishes and contribute in a direct way to the large fishable populations in coastal zones. Flagellates, on the other hand, are frequently poor foods for most grazers and can lead to undesirable eutrophication effects. Arguments are presented that silicon is often the controlling nutrient in altering a diatom to a flagellate community. The alteration is governed by the relative magnitudes of the natural fluxes of the nutrients nitrogen, phosphorus and silicon to the receiving water body and the recycled fluxes of nitrogen and phosphorus from zooplankton grazing and phytoplankton respiration and decomposition. Examples of such alterations are presented for oceanic, estuarine and inland water bodies.
THESIS
We can delineate several phytoplankton-based ecosystems in the coastal zone which may be altered by human introduction of nutrients and other biostimulatory chemicals into the ocean. Two such systems are of particular importance. One is the ecosystem dominated by diatoms which are the usual food for filter feeding fishes and zooplankton and contribute in a direct way to the large fishable populations in coastal zones. Diatoms grow very rapidly, have short lifetimes, are grazed heavily, and are rarely a nuisance. The other is the nondiatom ecosystem usually dominated by flagellates, including dinoflagellates, chrysophytes, chlorophytes and coccolithophoridae, though it also may contain large proportions of nonmotile green and bluegreen algae, particularly in brackish and estuarine environments. For convenience, the latter will be referred to here as the 'flagellate' ecosystem.
Flagellates persist for longer periods of time, many are known to be poor foods for most grazers, and the motile species are able to concentrate to undesirable concentrations due to their ability to swim and respond to light. Certain dinoflagellate epidemics, for example, are serious pollution events that must be understood to be predicted and controlled.
To our knowledge all excessive marine phytoplankton growths which have led to undesirable eutrophication effects have been related to flagellate blooms. These eutrophication effects can take several forms. One, the excessive growth, which is not grazed, can lead to oxygen deficiencies when the organic particulate matter sinks and subsequently consumes oxygen by respiration and decay. Such anoxic conditions can lead directly to fish and shellfish kills. Two, the toxic dinoflagellates, including some red tides, can adversely effect the marine ecosystem and can poison man through the consumption of shellfish which have filtered out the toxic components. Three, the flagellate blooms can reach proportions which discolor the water and make it unsightly and malodorous, reducing its esthetic and recreational value.
Diatoms require the major nutrients nitrogen, phosphorus and silicon for their photosynthesis; diatoms use silicon in approximately a one-to-one atomic ratio with nitrogen (Redfield et al., 1963). The flagellates associated with coastal eutrophication effects need only nitrogen and phosphorus, together with the trace elements and micronutrients that all autotrophs require.
Pg 5
H. Peterson (personal communication) states that San Francisco Bay does not at present have excessive or undesirable phytoplankton concentrations or conditions that might lead to the development of predominantly nuisance species or to serious dissolved oxygen deficiencies except locally, as in tributary streams along the margins. He cautions, however, that a significant reduction in the amount of available silicate that would accompany large scale diversions of freshwater inflow could alter this situation.
Pg 6
We suggest that the silicon in the bloom area was removed during the spring diatom bloom and that the recycled nitrogen and phosphorus provided the nutrient pool for the summer algal bloom.
CONCLUSIONS
Arguments have been presented as to the importance of the nutrient silicon in altering a generally desirable, diatom phytoplankton population to a frequently undesirable, flagellate phytoplankton population and consequent eutrophication effects. If these arguments are accepted, several possible conclusions follow. We mention three. One, rather than considering treatment procedures which remove the nutrients nitrogen and phosphorus from a sewage discharge into a eutrophied region, one might consider the addition, if feasible, of silica in quantity at the discharge site to alter the receiving waters to a diatom population and a consequent fertile and productive region. Two, regions with substantial natural silica inputs can toler ate larger sewage inputs of nitrogen and phosphorus before undesirable eutrophication effects occur. Three, as in Lake Michigan silica measurements are a critical key to the determination of the onset of undesirable eutrophication effects.
Officer, C B., Ryther, J H (1980).
The possible importance of silicon in marine eutrophication.
Mar. Ecol. Prog. Ser 3: 83-91
Earth Sciences Department, Dartmouth College, Hanover, New Hampshire 03755, USA
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
ABSTRACT: Diatom phytoplankton populations are the usual food for zooplankton and filter feeding fishes and contribute in a direct way to the large fishable populations in coastal zones. Flagellates, on the other hand, are frequently poor foods for most grazers and can lead to undesirable eutrophication effects. Arguments are presented that silicon is often the controlling nutrient in altering a diatom to a flagellate community. The alteration is governed by the relative magnitudes of the natural fluxes of the nutrients nitrogen, phosphorus and silicon to the receiving water body and the recycled fluxes of nitrogen and phosphorus from zooplankton grazing and phytoplankton respiration and decomposition. Examples of such alterations are presented for oceanic, estuarine and inland water bodies.
THESIS
We can delineate several phytoplankton-based ecosystems in the coastal zone which may be altered by human introduction of nutrients and other biostimulatory chemicals into the ocean. Two such systems are of particular importance. One is the ecosystem dominated by diatoms which are the usual food for filter feeding fishes and zooplankton and contribute in a direct way to the large fishable populations in coastal zones. Diatoms grow very rapidly, have short lifetimes, are grazed heavily, and are rarely a nuisance. The other is the nondiatom ecosystem usually dominated by flagellates, including dinoflagellates, chrysophytes, chlorophytes and coccolithophoridae, though it also may contain large proportions of nonmotile green and bluegreen algae, particularly in brackish and estuarine environments. For convenience, the latter will be referred to here as the 'flagellate' ecosystem.
Flagellates persist for longer periods of time, many are known to be poor foods for most grazers, and the motile species are able to concentrate to undesirable concentrations due to their ability to swim and respond to light. Certain dinoflagellate epidemics, for example, are serious pollution events that must be understood to be predicted and controlled.
To our knowledge all excessive marine phytoplankton growths which have led to undesirable eutrophication effects have been related to flagellate blooms. These eutrophication effects can take several forms. One, the excessive growth, which is not grazed, can lead to oxygen deficiencies when the organic particulate matter sinks and subsequently consumes oxygen by respiration and decay. Such anoxic conditions can lead directly to fish and shellfish kills. Two, the toxic dinoflagellates, including some red tides, can adversely effect the marine ecosystem and can poison man through the consumption of shellfish which have filtered out the toxic components. Three, the flagellate blooms can reach proportions which discolor the water and make it unsightly and malodorous, reducing its esthetic and recreational value.
Diatoms require the major nutrients nitrogen, phosphorus and silicon for their photosynthesis; diatoms use silicon in approximately a one-to-one atomic ratio with nitrogen (Redfield et al., 1963). The flagellates associated with coastal eutrophication effects need only nitrogen and phosphorus, together with the trace elements and micronutrients that all autotrophs require.
Pg 5
H. Peterson (personal communication) states that San Francisco Bay does not at present have excessive or undesirable phytoplankton concentrations or conditions that might lead to the development of predominantly nuisance species or to serious dissolved oxygen deficiencies except locally, as in tributary streams along the margins. He cautions, however, that a significant reduction in the amount of available silicate that would accompany large scale diversions of freshwater inflow could alter this situation.
Pg 6
We suggest that the silicon in the bloom area was removed during the spring diatom bloom and that the recycled nitrogen and phosphorus provided the nutrient pool for the summer algal bloom.
CONCLUSIONS
Arguments have been presented as to the importance of the nutrient silicon in altering a generally desirable, diatom phytoplankton population to a frequently undesirable, flagellate phytoplankton population and consequent eutrophication effects. If these arguments are accepted, several possible conclusions follow. We mention three. One, rather than considering treatment procedures which remove the nutrients nitrogen and phosphorus from a sewage discharge into a eutrophied region, one might consider the addition, if feasible, of silica in quantity at the discharge site to alter the receiving waters to a diatom population and a consequent fertile and productive region. Two, regions with substantial natural silica inputs can toler ate larger sewage inputs of nitrogen and phosphorus before undesirable eutrophication effects occur. Three, as in Lake Michigan silica measurements are a critical key to the determination of the onset of undesirable eutrophication effects.
Subscribe to:
Posts (Atom)
