This omission was understandable, Mr. Tollefsen said, because the loss of nitrogen from shellfish removal in most estuaries usually was not significant. Chesapeake Bay, for instance, has far more sources of nitrogen, he said, so that the export of nutrients in the form of shellfish is more than compensated for and does not matter in the total scheme of things. To prove his point, Mr. Tollefsen described how after the Southwest Sewer District in western Suffolk replaced thousands of individual cesspools, quahog production in Great South Bay decreased from 675,000 bushels in 1976 to 12,000 bushels so far this year. He said the sewer system effluent, which is pumped into the Atlantic, dumps 3,000 pounds of nitrogen each day. Much of that nitrogen once flowed into the bays via groundwater and leaching septic systems.
Clams are filter feeders.
If I were a clam in the Peconic Bay last July and trying to fatten up to reproduce, I would have to pump four times the amount of water to get the same amount of food as a clam did in the Great South Bay in 1975. Super Clams Mr. Tollefsen said the venerable Blue Point company, with shellfish farms in the Great South Bay, went out of the clam business this year because it was taking 10 years to grow a clam to marketable size. He said his theory was consistent with the observation that the brown tide seems to coincide with drought periods. Rain increases the amount nitrogen via road runoff and groundwater infiltration. There's no brown tide.