DOWN here at the end of Manhattan, on the border between evacuation zones B and C, I’m prepared, mostly. My bathtub is full of water, as is every container I own. My flashlights are battery-ed up, the pantry is crammed with canned goods and I even roasted a pork shoulder that I plan to gnaw on in the darkness if ConEd shuts down the power.

But as I confidently tick off all the things that Governor Andrew M. Cuomo recommends for my defense as Hurricane Sandy bears down on me, I find I’m desperately missing one thing.

I wish I had some oysters.

I’m not talking about oysters to eat — although a dozen would be nice to go with that leftover bottle of Champagne that I really should drink if the fridge goes off. I’m talking about the oysters that once protected New Yorkers from storm surges, a bivalve population that numbered in the trillions and that played a critical role in stabilizing the shoreline from Washington to Boston.

Crassostrea virginica, the American oyster, the same one that we eat on the half shell, is endemic to New York Harbor. Which isn’t surprising: the best place for oysters is the margin between saltwater and freshwater, where river meets sea. Our harbor is chock-a-block with such places. Myriad rivers and streams, not just the Hudson and the East, but the Raritan, the Passaic, the Kill Van Kull, the Arthur Kill — the list goes on and on — flow into the upper and lower bay of the harbor, bringing nutrients from deep inland and distributing them throughout the water column.