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R.I. Shellfish Offer Clue to Health of Chesapeake
By Elizabeth Williamson
Washington Post Staff Writer
Monday, May 8, 2006

Although 4.5 billion creatures died, the whole thing might have gone unnoticed, except for a couple of Brown University ecologists who dived to the bottom of Rhode Island's Narragansett Bay in the summer of 2001. There they found acres of blue mussels, suffocated by pollution-related oxygen loss in the bay waters.

The grim discovery triggered a study that has given experts new insights into the crucial role that shellfish play in maintaining the health of estuaries worldwide, documenting that reefs of mussels and other shellfish serve as powerful water filters, food sources and habitat for other species.

"What we captured in 2001 was the loss of those mussels and implications for an entire ecosystem," said Brown University ecologist Andrew Altieri, who with biology professor Jon Witman wrote the study published in the March issue of Ecology. "That's instructive for what historic and future losses might be for the Chesapeake."

Rhode Island's Narragansett Bay holds only one-twentieth as much water as the Chesapeake, but both are shallow and relatively slow-flushing, with plenty of people and industry nearby. And both suffer from summer bouts of hypoxia caused when excess nitrogen and phosphorus, chiefly from fertilizer runoff and sewage plants, feed "blooms" of microscopic algae too numerous to be eaten by other creatures. The algae die and decompose in a process that hogs oxygen.

Intense hypoxia, with algae's miles-long blooms, creates massive "dead zones," areas too starved of oxygen to support much life. The United Nations estimates that over the past 15 years, the number of waters harmed by hypoxia has doubled. Last year, about 5 percent of the Chesapeake Bay was classified as a dead zone.

Warm weather, scant wind and heavy rain can all spur hypoxic events. But the biggest factor is the nitrogen-laden spring runoff pouring into estuaries right now.

By the end of May, "you've set things up for the way the summer is going to look," said Dave Jasinski, water quality analyst for the Chesapeake Bay Program. For that reason, this year's spring drought bodes well for the bay, he said.

Only radical reductions in nitrogen and phosphorus dumping can eliminate hypoxia. But the group of hinged shellfish called bivalves have an amazing capacity to stem the condition. Lying on the bottom like tiny vacuum units, they constantly pull in water, eat algae called phytoplankton and spew clear water back out.

In the Narragansett, mussels and clams such as the locally renowned quahog do most of this work. But because they live on the bottom, they are themselves susceptible to hypoxia. The result is a double loss: of the animal and a vital self-cleansing mechanism.

The Chesapeake, the nation's largest estuary, is a premier example of this. Historically, oysters were the dominant shellfish in the bay -- as they were in the Narragansett until the 1930s -- but overfishing and disease have all but killed off the Eastern Oyster. Today, despite decades of restoration efforts, the oyster population remains less than 1 percent of what it was in 1880, the dawn of the region's oyster industry.

"It's criminal, really," said Roger Newell, professor at the University of Maryland Center for Environmental Science, who studies the impact of oysters. "It's a keystone species -- once it's removed from the environment, that system is irreversibly deteriorated."

Oysters make superior filters for three reasons. They process water at a rate of two to three times that of mussels. The Chesapeake's oysters generally live in high-oxygen shallows and tributaries, where they are less susceptible to hypoxia. And as the oysters feed and excrete, they also remove nitrogen from the water in a process similar to one used by sewage treatment plants.

Newell calculated that at their current numbers, the bay's oysters would need a year to filter its entire volume.
But without enough shellfish around, Newell must rely on computer models to estimate the impact. "This is all educated arm-waving, because you can't go back in time," he said.

That historical view is what Altieri and Witman gained in Rhode Island. Ironically, the pair were investigating an unusual boom in blue mussels in 2001 that local watermen called "a once-in-20-years occurrence," Witman said. The nine reefs they studied covered the equivalent of 229 football fields. Lying open in rows, the creatures gleamed blue-black and red, attracting crabs, sea stars and fish that eat them and live in the reefs. Snorkeling over them, the ecologists could see the reefs through 20 feet of water in a bay where average visibility is about four feet.

Altieri calculated that the reefs were processing the bay's entire water volume once every 20 days, even though they covered less than 1 percent of the bay floor.

Then one day in August, the men saw sea stars and crabs in the reefs climbing higher, searching for oxygen. Altieri noted that dissolved oxygen in the water had plummeted.

Within days, a hypoxic episode triggered by warm weather, low wind and the usual nutrients contributed to fish kills and beach closures around the bay. Two months later, mussels lay scattered like broken pottery on the bay floor, silted over and empty, more than 4 billion of them. Their filtering capacity had dropped by 75 percent.

One reef died entirely. A year later, seven of the other eight were mostly dead, too.
"The magnitude of mortality that hypoxia could cause . . . had never been documented" in the Narragansett, Witman said. "We had the ability to look at effects on individual species and the entire ecosystem." The damage from that one event, they estimated, could take more than a decade to undo.

The study has stocked the arsenals of the Chesapeake's oyster restoration advocates. Virginia and Maryland have spent tens of millions of dollars on oyster restoration and billions on bay cleanup over the past three decades, but they have not significantly curtailed oyster harvests. Meanwhile, the beleaguered industry has turned to a mechanized process called "power dredging" to maximize skimpy harvests, further threatening the oyster population. Some have proposed introducing a disease-resistant Asian species, but environmentalists argue that could have unintended consequences for the bay's battered ecosystem.

"It's very compelling," Maryland's Newell said of the Narragansett report. "The more examples like that we have, maybe we can get people" -- he paused for a short laugh -- "to actually change policies."

(c) 2006 The Washington Post Company
 

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OK this idea has been bugging me for a several months now. A while back they decided that phosphorous was a big deal in the Chesapeake Bay watershed. One of the major sources was laundry detergent. What did they do? They banned the sale of laundry detergent containing phosphorous within that same watershed.

OK so now the two big sources of nitrogen loading are sewage treatment plants and lawn fertilizer. Now the states are starting to modernize the sewage treatment plants.

So here is the big very simple question . . . Why can't they also ban the sale of lawn fertilizer in the watershed?

Tom
 

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Discussion Starter #5
I thought this reference to power dredging was particular good.

The study has stocked the arsenals of the Chesapeake's oyster restoration advocates. Virginia and Maryland have spent tens of millions of dollars on oyster restoration and billions on bay cleanup over the past three decades, but they have not significantly curtailed oyster harvests. Meanwhile, the beleaguered industry has turned to a mechanized process called "power dredging" to maximize skimpy harvests, further threatening the oyster population. Some have proposed introducing a disease-resistant Asian species, but environmentalists argue that could have unintended consequences for the bay's battered ecosystem.
Skimpy harvest?
Lets allow power dredging so we can get the very last one!
(sarcasm intentional...)

What needs to be done is to close the Bay to oyster harvesting... period.
What do you think the odds are that DNR would do that? [sad]
 
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[Q]Megabyte originally wrote:
I thought this reference to power dredging was particular good.

The study has stocked the arsenals of the Chesapeake's oyster restoration advocates. Virginia and Maryland have spent tens of millions of dollars on oyster restoration and billions on bay cleanup over the past three decades, but they have not significantly curtailed oyster harvests. Meanwhile, the beleaguered industry has turned to a mechanized process called "power dredging" to maximize skimpy harvests, further threatening the oyster population. Some have proposed introducing a disease-resistant Asian species, but environmentalists argue that could have unintended consequences for the bay's battered ecosystem.
Skimpy harvest?
Lets allow power dredging so we can get the very last one!
(sarcasm intentional...)

What needs to be done is to close the Bay to oyster harvesting... period.
What do you think the odds are that DNR would do that? [sad]

[/Q]

The oyster harvest in the winter of 2005-2006 doubled from the previous year without power dredging above the Choptank River.

The odds of closing the oyster harvest are about the same as the odds that the human population will decrease to a point that will help the bay.[sad]
 

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Discussion Starter #7
[Q]Capt. Mike Anderson originally wrote:
The odds of closing the oyster harvest are about the same as the odds that the human population will decrease to a point that will help the bay.[sad]
[/Q]

Very true Mike.

There isn't anything we can do to decrease the human population in the Bay watershed...
However, we (or rather, DNR) could put a halt to oystering in the Bay until the bivalve population recovers.

One is do-able, the other is not.
 

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Kevin

Because you can’t raise oysters in a septic tank, your wish that the harvesting stop will probably come to pass in 5 years or so. The only problem is all oysters will be dead from disease and pollution along with the bay. People blaming others for the problem need to look in the mirror at the real culprit.

Saying one is do-able and the other is not, reminds me of the guy who said kill half the population and the bay will straighten itself out. Killing half is also do-able. Does it make it morally right?

The bivalve population will never recover unless the bay is cleaned up. Banking on menhaden and oysters to even put a dent in the problem is wishful thinking even without a harvest.
 

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Discussion Starter #9
If we kill all of the oysters (and the menhaden), the Bay will always be dirty because we will have forcefully removed its natural filters.
The Bay needs the filter feeders in order to survive. We cannot loose sight of that fact.
 

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[Q]Megabyte originally wrote:
If we kill all of the oysters (and the menhaden), the Bay will always be dirty because we will have forcefully removed its natural filters.
The Bay needs the filter feeders in order to survive. We cannot loose sight of that fact.

[/Q]

The bays natural filters are not geared to remove chemicals, silt, and sewage. The bay cannot survive unless they are removed or at least reduced 50%.
 

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Big Mike
The Bay will never be cleaned up until filter feeders have been emplaced in it first, or you get about 50% of the population out of the watershed. The State and Feds have been treating wastewater, ind., san. for years with some effect, but not enough to remove hypoxia, dead zones. Nature provided these filter feeders to do what they do, and we changed the ecology by removing them, as well as wetlands to soak up runoff, which BTW has increased dramatically from construction. The Bay as a esturay is essentially a big septic tank. I saw how small mussels cleaned up a couple of very polluted creeks a few years ago. Your point about placing oysters in a polluted area is well founded, however, there are areas which are not hypoxic and there may a synergistic affect by emplacing oysters in areas which can support habitat. The cost of oysters vs the cost of a massive cleanup is small. The public is not yet ready to foot the cost of the massive cleanup in many billions maybe hundreds. Think of the cost of the cleanup up billions of gallons of runoff from urban and farm areas vs the cost of oysters, then add the air pollution costs.
 

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Do a little research on the zebra mussel in the Great Lakes. Everyone thought it was the end of the World but guess what? They filtered the water and now it's clean. Are there downsides? sure.
Can't believe I'm saying this but I agree with Reds that stopping Oyster harvesting will do nothing. Native oysters can not survive in the current water conditions. They only survive by powerdreging and planting spat. See Reds, I do listen & learn. I don't agree that DNR money is used to support a put and take oystery. But that's a different topic
It's not all doom and gloom. Ehrlich's flush tax is slated to reduce nitrogen in the Bay by some 30%. I think that will make a significant difference. Elkton has just started construction on it's new plant and I'm curious to see if it makes a difference. The old plant is a dirty one.
I'm told the name Susquehanna means 'muddy river' in native Indian. The Flats didn't just 'appear' 100 years ago. Have a little faith in Mother Nature. Dinosaurs are gone. Something came after them. Not trying to sugar coat it but, it could be worse.
 

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Discussion Starter #13
[Q]scotty80 originally wrote:
Native oysters can not survive in the current water conditions.[/Q]

I wonder how they would do if the water were a little cleaner?
What if there were more menhaden in the Bay to help out?
What if the mussles helped too?
Finally... if the gov's flush tax works and the wastewater discharge is really cleaner, would that help the oysters to survive and overcome the disease that is killing them now?
 

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The mussels can't survive in brackish water, so again no magical cure for the bay’s ills.

Some years they probably would survive down to the bay bridge but not this year.

Kevin

No one knows whether the diseases will disapear if the water is cleaner. Since their appearance, the water has not been clean enough to tell.
 

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It costs a lot less to leave the oysters and menhaden in the Bay than it does to replace their contribution by upgraded treatment plants. Yes the small numbers of oystermen & fishermen that will need to be compensated for lost livelyhood will be need to be borne, but the middlemen on down (up?) the foodchain will be supplied from other places. The crab market (flooded with foreign crabs ) for example.

I'm all for taxing the $#@% out of lawn fertilizer....
 

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Just to clarify, I did not mean to suggest that zebra mussels should be introduced into the Ches Bay. I meant to show how effective filter feeders can be.
 

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I don't know about in MD portion of bay, but in VA there are oysters living and reproducing on their own. Maybe if we give them a chance we could introduce these in other parts of the bay.
 

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[Q]Tom Powers originally wrote:
A while back they decided that phosphorous was a big deal in the Chesapeake Bay watershed. One of the major sources was laundry detergent. What did they do? They banned the sale of laundry detergent containing phosphorous within that same watershed.

[/Q]

I remeber that, but I don't remember it being Chesapeake Bay specific. I thought it was a national ban. Does anyone remember who the prime movers were in getting it banned?
 

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[Q]scotty80 originally wrote:
I agree with Reds that stopping Oyster harvesting will do nothing. Native oysters can not survive in the current water conditions. They only survive by powerdreging and planting spat.
[/Q]

To my way of thinking, doing nothing is doing nothing. Leaving the last remaining oysters will not clean the bay up by itself, no. But it is a step in the right direction. If there are no more oysters by the time we get the water clean, then what?

I'm guessing that power dredging uncovers old beds to allow new spat to attach, but you're taking out viable filter feeders to allow new ones to grow? If a shell bed is 100 sq feet and you power dredge the top layer, you still only have 100 sq feet of filtration, yes? Now if you dropped that living layer alongside the bed, then you'd have more filteration. ( I don't know if that would work in reality, if the oysters would survive, but the idea that harvesting a dwindling population is somehow improving things seems a stretch)
 

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I believe it was geared to the Chesapeake and wasn't that when all the Save the Bay stickers started. Seems like it was in the late 80's.
 
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