Blue crab mortality: interaction of temperature and DDT residues.

Serial observations of DDT-contaminated and uncontaminated salt marshes in the norther Gulf of Mexico were made in November and December, 1973. Blue crab (Callinectes sapidus) mortalities observed in the DDT-contaminated marsh during this period were correlated with reduced daily temperature minima. Gas chromatographic analysis of hepatopancreas and swimmeret muscle tissue of dead and dying crabs revealed total DDT residue concentrations as high as 39.0 ppm and 1.43 ppm, respectively. It is suggested that the DDT body burdens and reduced temperatures interact to produce acutely toxic effects. Several physiological and behavioral mechanisms are proposed.