Those who find reason to celebrate that the Gulf isn’t quite dead shouldn’t be surprised a few weeks from now, in a few months or a few years, when there’s a call that something has gone terribly wrong: The marshes that provide 95 percent of our seafood harvest are disintegrating; the crabs, shrimp, oysters and fish we once caught abundantly are suddenly scarce or nowhere to be found.
The oil some people claim has disappeared is sending a shudder through the life of the Gulf. Its impacts will manifest in ways that none of us are smart enough to fully predict or calculate.
To understand how it all unravels, you have to understand how the Gulf has built a pyramid of life to support its bounty.
I’m keeping my eye on the few parts of this great body that I can easily see and comprehend, particularly that little snail they call the marsh periwinkle (winkles, they call them fondly in England, where they’re abundant and prized delicacies).
In each square yard of Gulf salt marsh, there may be 100 or more of these dollop-sized snails — so many that the marsh sometimes reverberates with their rasping.
Small as they are, they’re capable of grazing salt marsh at a prodigious rate, mowing down, with the help of a fungus, far more marsh than they actually consume.
No one worries about the winkles when the marsh is healthy.
The reeds and grasses of the marsh grow faster than the snails can eat them, and the snails in turn provide a rich diet for crabs, turtles and birds, and by extension all the fish, shrimp and other creatures that depend on healthy marsh.
But what happens when the growth of marsh has been shackled by the pools of oil that have gathered around its roots?
The robust marsh grasses may — and almost certainly will — survive the immediate toxicity of the oil. The oil-consuming bacteria of the marsh will consume some, and the rest will sink out of sight, deeper in the marsh soil, sucking up the oxygen and nutrients the marsh itself needs to keep growing.
The marsh survives for months, maybe a year or two, but there’s every reason to believe it could be crippled, growing too slowly to keep up with the appetites of the snails.
And what happens when much of this year’s crop of crabs — the major predators of the snails — doesn’t return to shore because the tiny and highly vulnerable young crabs were suspended helpless, deep in the Gulf, when the oil hit?
What happens when next year’s class of fiddler crabs is stunted and deformed from repeatedly burrowing through oiled marsh? What then controls the rabbitlike reproduction of the snails?
The amusing winkles we thought were safe to ignore become, thanks to the effects of the oil, a cancer spreading through Gulf salt marshes, denuding the landscape.
When the grasses go, the very ground underneath them dissolves, swallowed by open water. No marsh, no birds, no young shrimp or fish, not even so much as a winkle.
We’ve seen it happen before on a small scale, in stressed marshes of Louisiana and the Chesapeake. Who’ll still be paying attention if the same thing happens Gulfwide?
The number of birds and sea life killed by direct contact with oil suddenly becomes inconsequential when compared to the number of creatures that could be eliminated in this kind of oil-induced collapse of the Gulf’s pyramid of life.
What previous spills have taught us is that such deadly cascades are almost inevitable when vast quantities of oil infiltrate a system.
Some of them, like the explosion of periwinkles, are predictable. Most of them are still unimaginable.
But the most severe impacts won’t be apparent until long after the oil drops out of sight.
