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Satellite observes agricultural runoff causing algal blooms
Space Daily ^ | December 9, 2004 | SPX

Posted on 12/09/2004 8:45:38 AM PST by cogitator

Direct Link Discovered Between Agricultural Runoff And Algal Blooms In Sea

Scientists have found the first direct evidence linking large-scale coastal farming to massive blooms of marine algae that are potentially harmful to ocean life and fisheries.

Researchers from Stanford University's School of Earth Sciences made the discovery by analyzing satellite images of Mexico's Sea of Cortez, also known as the Gulf of California - a narrow, 700-mile-long stretch of the Pacific Ocean that separates the Mexican mainland from the Baja California Peninsula.

Immortalized in the 1941 book Sea of Cortez, by writer John Steinbeck and marine biologist Edward Ricketts, the region remains a hotspot of marine biodiversity and one of Mexico's most important commercial fishing centers.

The results of the Stanford study will be presented at the annual meeting of the American Geophysical Union (AGU) in San Francisco on Dec. 13.

Algal blooms

Algal blooms occur naturally when cold-water upwellings bring from the seafloor to the surface nutrients that stimulate the rapid reproduction and growth of microscopic algae, also known as phytoplankton. These events often benefit marine ecosystems by generating tons of algae that are consumed by larger organisms.

But several phytoplankton species produce harmful blooms, known as red or brown tides, which release toxins in the water that can poison mollusks and fish. Excessively large blooms can also overwhelm a marine ecosystem by creating oxygen-depleted "dead zones" in the ocean.

Scientists have long suspected that many harmful blooms are fueled by fertilizer runoff from farming operations, which in many regions pour tons of excess nitrogen and other nutrients into rivers that eventually flow into coastal waters. However, some agricultural industry groups contend that there is not enough evidence to link farm runoff to red tides or dead zones.

Satellite imagery

To assess the impact of agriculture on marine algae, Stanford scientists turned their attention to one of Mexico's most productive coastal farming regions - the Yaqui River Valley, which drains into the Sea of Cortez.

"The Yaqui Valley agricultural area is 556,000 acres [225,000 hectares] of irrigated wheat," said Pamela A. Matson, the dean of Stanford's School of Earth Sciences and co-author of the AGU study. "The entire valley is irrigated and fertilized in very short windows of time during a six-month cycle. The excess water from irrigation runs off through streams and channels into the estuaries, and then out to sea."

Matson and her colleagues wondered if each fertilization and irrigation event would trigger a noticeable phytoplankton bloom near the mouth of the Yaqui River, which is located on the mainland side of the Sea of Cortez.

To find out, the researchers analyzed a series of images from an orbiting NASA satellite called SeaWiFS, which is equipped with special light-sensitive instruments that can detect phytoplankton floating near the surface of the sea.

"These instruments measure the level of greenness in the water," explained Kevin R. Arrigo, an associate professor of geophysics at Stanford and co-author of the AGU paper. "The greener the water, the more phytoplankton there are."

Dramatic results

Stanford doctoral candidate Mike Beman carefully analyzed dozens of SeaWiFS images taken over the Sea of Cortez from 1998 through 2002. The results were dramatic.

"I looked at five years of satellite data," said Beman, lead author of the study. "There were roughly four irrigation events per year, and right after each one, you'd see a bloom appear within a matter of days."

Each bloom was enormous, he said, covering from 19 to 223 square miles (50 to 577 square kilometers) of the Sea of Cortez and lasting several days. "Sometimes eddies actually pulled the plumes across the gulf, from the mainland side all the way to the Baja Peninsula," Beman added.

"Mike found that immediately following each one-week window in which much of the valley was irrigated, there was a response in the ocean off the coast of the Yaqui Valley," Matson explained.

"We were quite surprised," Arrigo added, noting that the AGU paper marks the first time that scientists have documented a "one-to-one correspondence between an irrigation event and a massive algal bloom."

Red tides and dead zones

According to the researchers, artificially induced algal blooms could have major impacts on recreational and commercial fishing, major industries in the Sea of Cortez. Red tides, for example, can cause outbreaks of life-threatening diseases, such as paralytic shellfish poisoning, which can shut down mussel and clam harvesting for long periods of time.

Another concern is hypoxia, or oxygen depletion, which is caused by excessive algae growth. As the algal mass sinks, it is consumed by bacteria, which use up most of the oxygen in the water as they multiply. The result is an oxygen-depleted dead zone at the bottom of the sea where few creatures can survive.

A massive dead zone appears every summer in the Gulf of Mexico off the coast of Louisiana and Texas. Scientists believe that agricultural runoff from the Mississippi River plays a pivotal role in creating this annual dead zone, which measured 8,500 square miles (22,000 square kilometers) in 2002-an area bigger than the state of Massachusetts.

"In the Sea of Cortez, there's the possibility that hypoxia could occur at a local scale, which could be devastating to the shrimp and shellfish industries," Matson said.

"Shrimp fisheries are very important economically, and they're already under a lot of stress from overfishing and aquaculture. It is possible that agricultural runoff could cause additional stress if it does lead to toxic blooms or hypoxia." She and her colleagues plan to conduct follow-up studies to assess the ecological impact of Yaqui Valley runoff events.

"The availability of high-resolution satellite data has opened up a whole new opportunity to look at the importance of what's going on on land in the sea," Matson added. "This study shows that you have to pay attention to the land-sea connections."


TOPICS: Business/Economy; Culture/Society; Extended News; Foreign Affairs; Government; News/Current Events
KEYWORDS: algae; coastalenvironment; ecoping; environment; farming; fertilizer; fishing; oceans; oxygen; phytoplankton; runoff; satellite
Living in the Chesapeake Bay watershed in Maryland, we're now paying a "flush tax" to pay for improvements in wastewater treatment plants to cut down on the amount of nutrients pouring into the Bay. Hopefully that'll help a little.
1 posted on 12/09/2004 8:45:39 AM PST by cogitator
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To: cogitator
Hopefully that'll help a little.

Until they start taking out those ChemLawn trucks with RPGs, I'm afraid the situation is hopeless. Every manicured lawn is dumping nutrients right into the watershed. It's all gotta go somewhere!

2 posted on 12/09/2004 8:55:13 AM PST by gridlock (ELIMINATE PERVERSE INCENTIVES)
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To: cogitator

This is a big problem in the Great Lakes region as well. From our digital orthophotos we can see algal blooms as well as sediment plumes coming from the tributaries. This is going to be a hotbed issue.


3 posted on 12/09/2004 8:56:06 AM PST by GreenFreeper
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To: cogitator; abbi_normal_2; Ace2U; adam_az; Alamo-Girl; Alas; alfons; alphadog; amom; AndreaZingg; ...
Rights, farms, environment ping.
Let me know if you wish to be added or removed from this list.
I don't get offended if you want to be removed.
4 posted on 12/09/2004 8:56:20 AM PST by farmfriend ( In Essentials, Unity...In Non-Essentials, Liberty...In All Things, Charity.)
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To: GreenFreeper
This is going to be a hotbed issue.

Excess nutrient input is probably the biggest remaining pollution problem in the United States right now -- most of the more noxious and dangerous chemicals and substances have been pretty well (with some exceptions) cleaned up. But improving stormwater runoff and wastewater treatment is difficult and expensive.

5 posted on 12/09/2004 9:01:38 AM PST by cogitator
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To: farmfriend

BTTT!!!!!!!


6 posted on 12/09/2004 9:02:18 AM PST by E.G.C.
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To: E.G.C.
Same problem on Mars

7 posted on 12/09/2004 9:04:13 AM PST by evets (God bless president George W. Bush)
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To: GreenFreeper; Carry_Okie; farmfriend

The solution to pollution is dilution, right???


8 posted on 12/09/2004 9:10:03 AM PST by SierraWasp (Ronald Reagan was an exceptional "celebrity!" Jesse Ventura & Arnold Schwarzenrenegger are NOT!!!)
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To: cogitator

I agree, I've done some work with the CSO (combined sewer overflow) problems in the Great Lakes region. Many communities still have these antiquated waste water treatment plants that discharge untreated water directly into lakes, streams, etc. after rain events. Instead of separating storm and sewer water, they often take the bandaid approach of increasing the plants water retention capacity. There are hundreds of communities that aren't in compliance with the EPA's NPDES (National Pollution Discharge Elimination System) permiting system. At least around here communities don't seem to care as the polluted water flows into surrounding communities, eventually ending up in Lake Michigan. A people wonder why the beaches are closed due to contamination.


9 posted on 12/09/2004 9:12:01 AM PST by GreenFreeper
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To: SierraWasp
The solution to pollution is dilution, right???

Very punny! But actually, you are correct...although it really doesn't solve the problem, it just disperses pollutants over a larger area.

10 posted on 12/09/2004 9:17:53 AM PST by Aracelis
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To: GreenFreeper

I grew up in New London, WI and went to college at UW-Oshkosh. One of the big environmental issues while I was in high school and college was the sad state of the Fox River that flows from Lake Winnebago to Green Bay. At the time, it was a mess. It's substantially better now, and the improvement shows that progress can be made. It's still got problems, mainly PCBs, but they're being addressed.


11 posted on 12/09/2004 9:27:36 AM PST by cogitator
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To: cogitator
I don't worry too much about PCB's, they often are trapped under the sediment layer. Evil environmental consulting firms (I can name quite a few) use somewhat stabilized PCB measures from underneath the sediment to push environmentally hazardous and costly dredging. Then they have no where to dump the toxic sediment, which begins a whole new debate.

Speaking of eutrophication, you ever go to Lake Koshkenog (spelling?). My grandmother lived on that lake near Edgerton, WI until she passed away a few years ago. That has to be the most algae fill lake I have ever seen!

12 posted on 12/09/2004 9:39:21 AM PST by GreenFreeper
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To: cogitator

Excess nutrient input is probably the biggest remaining pollution problem in the United States right now
=====
Considering all of today's triumphant technology, surely there must be a way to convert excess nutrient input to a new form of breathtaking breakfast cereal !!! ;-))


13 posted on 12/09/2004 9:41:19 AM PST by GeekDejure ( LOL = Liberals Obey Lucifer !!!)
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To: GreenFreeper
Speaking of eutrophication, you ever go to Lake Koshkenog (spelling?). My grandmother lived on that lake near Edgerton, WI until she passed away a few years ago. That has to be the most algae fill lake I have ever seen!

Koshkenong. I've been by it on I-90 but never actually to it. Any idea why it was so green? (There's a lot of dairy around there -- I might be able to guess.)

14 posted on 12/09/2004 9:52:36 AM PST by cogitator
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To: cogitator

Not until they quit dumping sewage sludge on agricultural land, (within 25 ft. of the water).


15 posted on 12/09/2004 9:55:14 AM PST by Smokin' Joe (I'm from North Dakota and I'm all FOR Global Warming!)
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To: cogitator
Let me see if I understand this correctly. Algal blooms can either be very good or very bad.

On the good side the nutrients are feeding algae that is important to the food chain in the ocean.

On the bad side, some types of algae release bad toxins.

Which happened in the blooms in Mexico?

I'm a bit skeptical about this report, because it seems to be leaving a lot of information out.

It talks about red tides and hypoxia, but it doesn't say that they saw evidence of those occurrences in the areas they were observing.

They mention problems with hypoxia at the end of Mississippi river, but they don't really show that they have any evidence to show that it's related to algal blooms or nutrient runoff. I suspect that there are a lot of different pollutants in the Mississippi river, what ties the hypoxia to the nutrients?

The article mentions bacteria that eats the algae uses up oxygen. However green algae is the biggest source of oxygen in the oceans. I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water. That kind of seems to violate the natural cycle.

""In the Sea of Cortez, there's the possibility that hypoxia could occur at a local scale, which could be devastating to the shrimp and shellfish industries," Matson said"

Sounds like another way of saying that we saw widespread evidence of algal blooms but no evidence of hypoxia, yet you should still be concerned because we say it could be happening.

""Shrimp fisheries are very important economically, and they're already under a lot of stress from overfishing and aquaculture. It is possible that agricultural runoff could cause additional stress if it does lead to toxic blooms or hypoxia." She and her colleagues plan to conduct follow-up studies to assess the ecological impact of Yaqui Valley runoff events."

Shrimp eat algae. So unless the runoff is causing toxic blooms, I would think that the shrimp population would thrive during algal blooms. If the shrimp populations are low, it sounds like there might be other causes.

It sounds like they gathered some good information with their research. However the tone of the article seems to imply that these algal blooms are bad. All they've done so far is show that the nutrients appear to effect algae growth, but they don't know what type of algae or if it's good or bad.

They appear to be concentrating on possible harm. It always scares me when environmentalists go into research and appear to already assume that there is harm being caused, and then look for evidence that they are right.
16 posted on 12/09/2004 9:55:22 AM PST by untrained skeptic
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To: Aracelis; Carry_Okie; farmfriend; Lurker; forester; Issa; B4Ranch
"...it just disperses pollutants over a larger area."

Too much concentration of just about anything can be considered a pollutant these days! The so called pollutants come directly, or indirectly from the ground and even the ground it'self is considered a "pollutant" by militant GANG-GREEN when ANY erosion occurs... it's called TURBIDITY and according to them... MUST be eliminated!!!

In 1998, I attended a much ballyhooed conference attended by both Clinton and Bruce Babbit at Lake Tahoe about lake clarity. As usual, one could only submit questions on 3x5 cards in advance. It rained heavily that day and I submitted two and one was "I noticed on the way in here through the parking lots that a lot of ugly yellow stuff was being washed down the parking lot drains and into the lake! It appeared to be coming from our beautiful pine trees! What program does the Federal Government have in place to stop this detrimental substance from polluting the lake?"

The other question I submitted was, "Erosion is perceived as the prime cause of degradation in lake clarity. Since the time Lake Tahoe was formed, how does one explain how all the buildable level and semi-level land got into this basin and the lake remain as pristine as it has been?"

17 posted on 12/09/2004 9:56:51 AM PST by SierraWasp (Ronald Reagan was an exceptional "celebrity!" Jesse Ventura & Arnold Schwarzenrenegger are NOT!!!)
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To: untrained skeptic
I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water.

Its more of an indirect effect. Untreated wastewater is generally rich in organic matter. This organic matter feeds the bacteria and algae normally present in healthy water sources. The presence of excessive amounts of nutrients discharged as a result of untreated wastewater will cause an increase in concentration of both bacteria and algae within the surface water. Beside organic matter, wastewater also contains both organic and oxidizable inorganic compounds. These organic and inorganic compounds directly and indirectly consume the available oxygen present in the ecosystem. This process is called eutrification and will eventually kill off other living organisms (plants, animals, & insects) in the aquatic system.

18 posted on 12/09/2004 10:02:53 AM PST by GreenFreeper
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To: FredZarguna

I meant to ping you to this discussion. I think you will probably have many enlightening things to add to offset my rhetorical questions, platitudes, puns and hypercritical replies. So get in here, quick!!!


19 posted on 12/09/2004 10:07:49 AM PST by SierraWasp (Ronald Reagan was an exceptional "celebrity!" Jesse Ventura & Arnold Schwarzenrenegger are NOT!!!)
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To: cogitator
Any idea why it was so green? (There's a lot of dairy around there -- I might be able to guess.)

From what little I know/remember of that area, Lake Koshkenog was formely farmland. The native americans farmed it previously and then I believe white settlers also farmed it. Somehow we altered the Rock River (most likely dammed upstream) and the farmland flooded. I remember hearing the Lake has only a maximum depth of 7 feet, so that would support that theory-- pretty shallow for a lake that size. So I would assume the lake bed soil was already pretty nutrient rich to begin with and I'm sure the nearby dairy industry doesn't help.

20 posted on 12/09/2004 10:12:32 AM PST by GreenFreeper
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To: untrained skeptic
You wrote a lot. In general, the issue with normal, non-toxic algal blooms is like a lot of other things; when they're normal, they aren't a problem. When there's too much, that can cause problems (likewise with too little).

It talks about red tides and hypoxia, but it doesn't say that they saw evidence of those occurrences in the areas they were observing.

They didn't; but the study supports the linkage between agricultural runoff and blooms that induce hypoxia elsewhere.

They mention problems with hypoxia at the end of Mississippi river, but they don't really show that they have any evidence to show that it's related to algal blooms or nutrient runoff. I suspect that there are a lot of different pollutants in the Mississippi river, what ties the hypoxia to the nutrients?

Pollutants that don't enhance phytoplankton growth don't participate in the process that causes hypoxia; they're just pollutants. Excess nutrients like nitrogen and phosphorus do enhance phytoplankton growth.

The article mentions bacteria that eats the algae uses up oxygen. However green algae is the biggest source of oxygen in the oceans. I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water.

Hypoxia is a problem on the sea floor. The algae die and sink to the bottom and get consumed by the bacteria. That's where the oxygen depletion occurs, not at the surface where the algae are growing.

Shrimp eat algae. So unless the runoff is causing toxic blooms, I would think that the shrimp population would thrive during algal blooms.

Shrimp breathe (respire), too, and they inhabit the bottom of the water body. If they are in waters that become hypoxic, they have to leave.

It sounds like they gathered some good information with their research. However the tone of the article seems to imply that these algal blooms are bad. All they've done so far is show that the nutrients appear to effect algae growth, but they don't know what type of algae or if it's good or bad.

I think it's more appropriate to say that excess algal blooms can be (but aren't always) bad. They don't really say that they've seen detrimental effects from this process in the Sea of Cortez, leading me to think that they haven't.

21 posted on 12/09/2004 10:25:49 AM PST by cogitator
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To: GreenFreeper
Thanks for the clarification. If I understand correctly there is bacteria feeding not just on the algae, but on other nutrients in the runoff. The net result is the bacteria uses more oxygen than the algae produces.

I wonder if it's possible to tailor the fertilizers used to be appetizing to good algae, but unappetizing to bad algae and harmful bacteria?
22 posted on 12/09/2004 10:27:56 AM PST by untrained skeptic
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To: cogitator
Thanks for all the info. A lot of my skepticism did result from not having enough knowledge on the subject to be able to follow the reasoning of the author as well as he probably expected his audience to be able to follow along.

It sounds like the still have some work to do to show cause and effect, but it seems like they're gathering good information.
23 posted on 12/09/2004 10:37:40 AM PST by untrained skeptic
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To: cogitator
We experience the same problems in the Great South Bay off of Long Island every few years; we call it brown tide.

The blooms have decimated the shell fishing industry in the region. It has also added to the decline in the fishing industry; although over fishing was probably the main culprit.

What was once a very bountiful ecosystem was experiencing a slow death.

Laws have helped in stabilizing the bay; in time it may one day came back. Only time will tell.




24 posted on 12/09/2004 10:55:37 AM PST by PigRigger (Send donations to http://www.AdoptAPlatoon.org)
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To: SierraWasp
a lot of ugly yellow stuff was being washed down the parking lot drains and into the lake! It appeared to be coming from our beautiful pine trees! What program does the Federal Government have in place to stop this detrimental substance from polluting the lake?"

ROFL! Pollen...Pollution...coincidence?

25 posted on 12/10/2004 9:36:32 AM PST by Aracelis
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To: Aracelis
"ROFL! Pollen...Pollution...coincidence?"

At a meeting headlined by one of the most corrupt Pollititions in history... Bill Clinton!!!

26 posted on 12/10/2004 9:53:38 AM PST by SierraWasp (Ronald Reagan was an exceptional "celebrity!" Jesse Ventura & Arnold Schwarzenrenegger are NOT!!!)
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