The effects of storage temperature and time on sediment toxicity

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