Monday, April 09, 2007
Cleaning the Chesapeake, one oyster at a time
The New York Times is running a fascinating op-ed piece this morning about oysters, their capacity to filter water, and why they are the key to cleaning up the Eastern seaboard:
This year marks 400 years since the founding of the Jamestown colony, a span in which everything about the area has changed, not least the water. When John Smith first encountered the Chesapeake, he was struck by its beauty and bounty. “Heaven and earth never agreed better to frame a place for man’s habitation,” he wrote. The water was clear, fish teemed in its depths, and oysters lay “as thick as stones” on the bottom.
Don’t try to look for those oysters today. They aren’t there. Even if they were, you wouldn’t be able to see them through the brown murk. Those oysters were the linchpin of a now-comatose ecosystem. Not only did they pave the bottom, providing footholds for aquatic plants, but they also formed prodigious “oyster reefs” 20 feet high and miles long that sheltered juvenile fish and crustaceans.
And they performed another vital function. Oysters eat algae. A single adult oyster can filter 50 gallons of water a day, and the uncountable billions that once inhabited the Chesapeake filtered the entire bay every few days. This allowed sunlight to penetrate to the bay bottom so eelgrass and other foundations of the food chain could thrive. By providing these three services — filtration, stabilization and habitation — oysters engineered the ecosystem.
Then they disappeared. Overharvesting was the main culprit, but pollution and disease played roles, too. Annual harvests on the Chesapeake plunged, from over 100 million pounds in 1880 to 20 million in 1960 and less than 250,000 pounds today.
Many East Coasters think that mid-Atlantic waters are supposed to look like brown soup. They’re not. Too many nutrients wash downstream from cities and farms, feeding algae blooms, and there aren’t enough oysters around to eat the algae. When the algae die and decay, they take the oxygen with them, causing the “dead zones” becoming all too common along America’s coasts.
Read the whole thing.
6 Comments:
By 
, at
Mon Apr 09, 01:28:00 PM:
The article is fascinating, but mostly by the author's extreme bias against non-native oysters. He reveals this quite clearly by comparing "Chinese oysters" to the zebra mussel.
Aquaculture cannot be sustained if the the product doesn't live long enough to reach the marketplace. although the native oyster, Crassostrea virginica was brought to the brink of ruin through over harvesting and habitat degradation, disease is its modern scourge. The oysters die off during the two years it takes them to reach market size.
Virginia, and to a lesser extent, Maryland have studied the introduction of a non-native oyster. Crassostrea gigas, an import which forms the base of the thriving Pacific Northwest oyster industry, proved unpromising. It fell to the same diseases as the native oysters and tasted lousy. However, Crassostrea ariakensis has shown great promise. It resists the diseases and reaches market size in about nine months. Plus, they taste good.
Our former Governor, Robert Ehrlich (Princeton class of 1979), attempted to accelerate the study and ultimate introduction of Crassostrea ariakensis. But, his plans were beat back amid calls for more study, more study grants, and more caution.
I will not get into oyster leaseholds in the bay or the waterman's and State's resistance to aquaculture. The University of Maryland has lots of good background on their web site. Try Googling on "Oyster Wars" to get the flavor. I will say that although I love oysters, I can no longer eat them. About 20 years ago I developed an allergy that has since spread to mussels, clams, and other bivalves. Not only do I become violently ill, I may also blackout or appear to be having a seizure!
By 
TigerHawk, at
Mon Apr 09, 03:40:00 PM:
I dunno, ID. The TigerHawk sister (Princeton '90) is an expert on invasive species, and has pretty much sold me on the idea that it is almost never smart to introduce them. Too hard to predict the consequences.
By , at
Mon Apr 09, 05:29:00 PM:
TH, your sis is right in that it is hard to predict what will happen when a new species is introduced. What is likely to happen is that the native Crassostrea virginica will be wiped out. I say "so what," "She should have died hereafter." A valid concern is that Crassostrea ariakensis would spread to waters outside of the Chesapeake watershed, perhaps threatening the famous Blue Point Oyster and others that are Crassostrea virginica (all east coast oysters are of that species). The main difference is that the proposal would replace oysters with other oysters. Not rabbits in Australia or nutria on the eastern shore of Maryland and in Louisiana.
My point is that the oyster in the Chesapeake is all but dead. If experts can't restore the bivalve population with a suitable species, then some rogue with a huge barge of imported oyster spat will.
Ask sis to ponder the alternatives. No oysters at all, or an introduced import that thrives?
By GreenmanTim, at
Mon Apr 09, 11:18:00 PM:
Introduced species in marine systems are notoriously hard to contain, so I agree with ID that the migration to other waters of Crassostrea ariakensis is a real concern for native oysters elsewhere along the east coast.
The idea of restoring damaged ecosystems that are lacking one or more keystone species that are now either non-viable or even extinct is an interesting one. There are forest systems in the Caribbean that evolved with frugiverous megafauna that once ate and spread the seeds of tree species but are now extinct. What else (mechanical, biological) could appropriately replace the role of these vanished species today in these systems?
There are folks who argue that fauna of North America is missing some meso and mega-carnivore species that died out at the end of the Pleistocene (American Cheetah, American Lion, Dire Wolf, Short-faced Bear) and what our overengineered pronghorn need to stay in peak condition are some faster introduced predators. I imagine that Montana Cheetah would not go down well with westerners, particularly the ranching community.
Finally, there are those on Martha's Vineyard who have investigated the introduction of the Greater prairie chicken to replace the extinct but related Heath Hen.
A lot depends on whether you believe that an ecological system has a range of available niches, and one can and should be able to substitute a comparable species (e.g. Eastern Coyote for Wolf in the Northeastern US in the slot for medium-sized canid carnervore). Actually,, the coyotes haven't waited for scientists and citizens to make a decision on this point: they are here now where 60 years ago there were none, and they are thriving, and managed it all on their own.
By , at
Tue Apr 10, 12:10:00 AM:
The oysters are only trying to hide from those twits at GREENPEACE those eco-wackos are a bunch of trouble makers especialy to us birds of paridise SQUAWK SQUAWK they dives me crazy SQUAWK SQUAWK SQUAWK
By Assistant Village Idiot, at
Wed Apr 11, 08:47:00 PM:
I am out of my depth (heh) on the current oyster issues. But as to the abundance of many species at the time of European arrival, that may have been only a temporary spike, not an edenic cornucopia which we destroyed. The indigenous peoples, who had previously fished, gathered, and hunted those areas, had quite recently been 90% wiped out by European diseases. Lacking these human predators, many species rapidly overpopulated before reverting to a stable population.
