Acute Toxicity of Yellow Phosphorus to Atlantic Cod (Gadus morhua) and Atlantic Salmon (Salmo salar) Smolts

The acute toxicity of yellow phosphorus (P4) to Atlantic cod (Gadus morhua) and Atlantic salmon smolts (Salmo salar) was investigated using two experimental procedures: (a) continuous exposure and (b) single brief exposure.In continuous-exposure experiments, P4 was lethal to cod and seawater-maintained salmon at concentrations as low as 1.89 and 0.79 μg/liter, respectively. Salmon that were exposed to P4 concentrations of 40 μg/liter or less developed a distinct external red color and showed signs of extensive hemolysis. At death, salmon that had been exposed to P4 concentrations of 90 μg/liter and lower showed a progressive decline in hematocrits. In contrast, cod were never observed to show any evidence of external redness, hemolysis, or reduced hematocrits.In the brief-exposure experiments, cod and salmon were subjected (20 min to 3.5 hr) to P4 concentrations ranging from 245 to 4030 μg/liter. These brief exposures resulted in mortalities to both species that were delayed for as long as 2 weeks. Salmon turned "red" 16–24 hr following exposure, and at death showed evidence of hemolysis and reduced hematocrits. None of the cod exhibited any of these symptoms.