FROM THE GULF OF MEXICO — Make a mistake about Gulf Coast oyster facts–say by running a picture showing Crassostrea gigas or Pacific oysters instead of Crassostrea virginica or Eastern oysters—and you are going to hear from Ed Cake.
Cake is practicing marine biologist with a Ph. D who has worked for the past couple of decades growing the Gulf oyster industry along side the oil business. He’d worked for both, usually at the same time as the two industries have tried to work through their shared interests in the Gulf.
Up and down the Gulf Coast, his familiar “Oyster 1” license plate can be found just about anytime industry and government officials are making oyster policy. He is a scientist adept in the world of Mississippi oyster and oil politics, giving the benefit of his knowledge in straight-talking English, not the mumbo-jumbo heard out of too many academic types.
With all the uncertainty surrounding the BP oil spill, Cake is the go-to guy for the answers everyone is asking, from the families that own the big seafood processing facilities to elected officials. They go to him because he knows his oysters.
“Remember,” Cake says, “a 3-inch oyster can filter up to 8 gallons of water an hour while feeding and everything in the water column surrounding the oyster can adversely affect it. All the particles, including oil droplets, that are in the range of 3 to 12 microns (millionths of a meter) will be ingested by the filter-feeding oysters.
“Those ingested oil droplets and other hydrocarbon residues in the digestive gland of the oysters may cause lesions in the digestive gland of oysters and lead to their death or to a reduction in their reproductive capabilities,” Cake adds.
“The oyster’s only hope is to tightly close its shells and live off internal body reserves until and unless the oil and its harmful components leave the area. If the oil remains for any length of time, the oyster may die outright for exposure to the oil and its components or succumb when its internal reserves are exhausted or when respiration ceases.”
Most of the television crews, sunbathers, and beach clean up crews up and down the Mississippi Gulf coast Wednesday afternoon—a strange mix on an otherwise sunny day–all seemed to expect a dark sticky oil slick to arrive any moment. Cake’s knowledge of oil in the Gulf brings out a longer explanation.
In his own words, here’s how he sees the likely impacts of the oil spill on oyster resources when the slick reaches the coastal waters of Louisiana, Mississippi, and Alabama.
OIL IN THE GULF
“To begin with, the lighter fractions spilled oil (the sheen) are already volatizing (vaporizing) and escaping into the atmosphere. On Sunday, May 3rd, hydrocarbon fumes from the offshore spill could be smelled in Ocean Springs on strong southwest winds off the Coast, an indication that the volitization process is ongoing.
“The heavier fractions of oil are already sinking into the Gulf and may not make it to the shoreline. They should not be a problem for the inshore oyster resources unless the spill continues to grow and comes into the bays and sounds in large volumes of floating oil that haven’t had time to break into the various components.
“The floating fractions are already being attacked by bacteria and will eventually become weathered ‘tar balls’ that are often found on our beaches, especially in the heat of the summer when they “melt” and foul our bare feet or shoes and sandals. Those ‘asphaltic’ tar balls result when all the short-chain hydrocarbon molecules are removed by bacterial degradation.
“If the oil spill is large enough in volume and aerial coverage, the floating oil will entrain air in rough sea conditions and become ‘chocolate mousse’ that the public is familiar with. When the “mousse” comes ashore or into the estuaries where oysters reside, it can cover and kill oysters outright or cause them to take on an ‘oily’ flavor that will make them inedible for a considerable time until natural purging occurs–in weeks or months if they don’t die from toxic contaminants in the oil.
OIL IN SHALLOW WATERS
“Oysters in shallow waters may become coated with floating oil at low tide and/or during rough sea conditions, thereby killing or stressing the oysters. They, too, would be unusable for harvest. The coatings of oil will also prevent new oyster spat from settling on shells or other suitable substrates in oyster-growing areas. So several generations of oysters may be lost.
“That leaves the soluble fractions that are already in the water column from the spilled oil. In large concentrations, toxic components of crude oil such as benzene and toluence can kill oysters and will kill oyster larvae. Those soluble factions can wreck havoc on other shellfish and finfish populations and marine food chains until those components are dissipated.
“Although oysters that are confronted with oil may survive the initial spill and its various components, they may form tissue lesions in their digestive gland in response to the digested oil. Those lesions may result in the death of the affected oysters and/or prevent natural reproduction (spawning); thereby causing a loss of future oyster spat sets (new, young-of-year oysters.).
“Depending on when and where and how much of the toxic oil dispersant chemicals (e.g. detergents) are applied to ‘make the spill go way,’ those chemicals may harm adult oysters as well as plank tonic oyster larvae in the water columns. Those dispersants also enable the crude oil components to ‘dissolve’ in the water columns, thereby causing additional problems for the oysters and their larvae as the filter feed.”
Finally, Cake provided Food Safety News with this list of oyster-related commercial and environmental problems that might result from the BP oil spill hitting the Gulf Coast:
-A “precautionary” shutdown of the Gulf oyster industry.
-The on-bottom oyster stocks could be lost.
-Consumer resistance to eating Gulf oysters out of fear of contamination or because of an “oily” taste.
-The fouling of shell substrates from the loss of future spat sets.
-An alteration of the organoleptic qualities of the Gulf oyster in taste, odor and texture that make them inedible.
-The Gulf oyster industry’s long-term recovery.