Influence of salinity on the bioaccumulation and photoinduced toxicity of fluoranthene to an estuarine shrimp and oligochaete.

The effect of salinity on the photoinduced toxicity of waterborne fluoranthene to larvae of the grass shrimp (Palaemonetes pugio) and tubificid oligochaete worms (Monopylephorus rubroniveus) was studied in a laboratory system under simulated sunlight. In the grass shrimp toxicity tests, five concentrations of fluoranthene (0, 3.6, 7.3, 13.8, and 29.0 microg/L) and four salinities (6.9, 14.5, 21.2, and 28.6 per thousand) were achieved. In the oligochaete toxicity tests, five concentrations of fluoranthene (0, 0.8, 1.4, 3.3, and 7.7 microg/L) and four salinities (7.1, 13.3, 20.5, and 27.6 per thousand) were achieved. Salinity had no effect on either the photoinduced toxicity or the bioaccumulation of fluoranthene in the grass shrimp. However, the highest level of salinity decreased the median lethal time for the oligochaete. Bioaccumulation of fluoranthene was inversely related to salinity for the oligochaete. Additional experiments demonstrated an inverse relationship between salinity and short-term osmotic weight change in the oligochaete. Weight of the grass shrimp larvae was not affected by salinity. These findings show that salinity can influence the toxicity and bioaccumulation of fluoranthene in some estuarine organisms. The influence of salinity on these populations may be related to physiological responses associated with internal osmotic volume changes. Thus, salinity needs to be taken into account when assessing the risk of photoactivated polycyclic aromatic hydrocarbon (PAH) to at least some estuarine species.