LETHAL AND SUBLETHAL EFFECTS OF THE SEDIMENT-ASSOCIATED PCB AROCLOR-1254 ON A MEIOBENTHIC COPEPOD

Acute toxicity tests were performed on field-collected copepods (Microarthridion littorale) using the sediment-associated polychlorinated biphenyl (PCB) Aroclor 1254 (i.e., PCB concentrations in bulk sediments in the bound and/or unbound states). Three replicates of 50 adult copepods (25 males + 25 females) were exposed to five levels of PCB-contaminated sediments for 96 h and compared to untreated controls and solvent controls. LC50 concentrations were nearly twice as high for females (251 mg/kg) as for males (117 mg/kg). To determine the effects of the PCB on reproductive output of the copepods, copulating pairs of Microarthridion littorale were allowed to reproduce in concentrations of Aroclor 1254-contaminated sediments below LC50 values. Two experimental trials with 10 and 15 replicates, each with one pair of Microarthridion littorale in copulus, were conducted for 12 d, the normal time needed for females to produce one set of nauplii and carry a second clutch of eggs. In both experiments, a significant decrease in number of nauplii was found with Aroclor contamination. Although NOECs were not determined, high concentrations (83 mg/kg) of the sediment-associated Aroclor 1254 were required to affect mortality significantly, whereas lower levels (4 mg/kg) impaired reproduction.