THE EFFECTS OF STORAGE-TEMPERATURE AND TIME ON SEDIMENT TOXICITY

The toxicity of an estuarine sediment stored at differ ent temperature s (- 22 degrees C, 4 degrees C, and 25 degrees C) was monitored over t ime (at 0, 2, 4, 7, and 20 weeks) by conducting 96 h suspended particu late phase (SPP) tests with 24- to 48-h-old Mysidopsis bahia. Toxicity generally increased with time for sediments stored at 4 degrees C and - 22 degrees C. For both temperature treatments, survival was reduced from 40% at week 0 to < 10% at week 12. Survival at 25 degrees C was much more variable, fluctuating between 10% and 90% during the experim ent. Reference toxicant tests with sodium dodecyl sulfate (SDS) were c onducted throughout the sediment storage experiment. Relative sensitiv ity to SDS was similar at all time periods except for week 20 where de creased sensitivity was observed. This decreased sensitivity to the re ference toxicant corresponded to a significant and uniform increase in survival to all stored sediment samples.