Differential haemotoxic effect of PCB congeners in the common shrimp, Crangon crangon.

1. Specimens of the common shrimp, Crangon crangon, were exposed to sub-acute logarithmically separated concentrations (ranging from 0.05 microgram to 500 micrograms l-1) of two structurally dissimilar PCB congeners (PCB 15 and PCB 77) for five days in vitro. 2. Mortality, recoverable haemolymph volume, haemocyte count, plasma protein and haemolymph osmolarity were determined for test animals together with levels of haemolymph cell prophenoloxidase, an indicator of immune potential. 3. Sub-acute concentrations of PCB 15, but not PCB 77, produced significant decreases in haemocyte count and phenoloxidase activity with a marked increase in recoverable haemolymph volume. 4. No effect was observed on haemolymph osmolarity or plasma protein levels with either PCB 77 or PCB 15.