Kinetics and Effects of DDT in a Tidal Marsh Ditch

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Abstract
A tidal marsh ditch near Pensacola, Florida was treated with 0.2 pound of DDT per acre in March 1963, and observed for 4 months. Ninety‐eight per cent of the animal mortality occurred within 3 weeks after treatment. A population of cyprinodont fish was restored by reproduction of surviving and introduced fish. DDT was detected in surface water samples 8 days after treatment but not after 14 days, while DDT was not detected in bottom water samples later than 1 day after treatment. Seven weeks after treatment, vegetation samples averaged 9.1 ppm of DDT, after reaching a maximum of 75 ppm of DDT 3 to 4 weeks after treatment. Sediment samples yielded more variable residues, averaging 0.76 ppm of DDT at 7 weeks after reaching a maximum of 3.35 ppm of DDT 6 weeks after treatment. Fish accumulated up to 90 ppm of DDT within 5 weeks after treatment. Highest DDT residues detected in fiddler crabs and snails ranged from 15 to 25 per cent of the average residues detected in fish. The net water movement as indicated by the distribution of Rhodamine B dye, the general distribution of DDT residues in all samples, and the difference in mortality of fish at two holding sites, indicated an accumulation of DDT in the lower marsh after treatment.