Effects of the carcinogenic polycyclic aromatic hydrocarbons (PAH), benzo(a)-pyrene (BAP), and methylcholanthrene (MCA) were investigated with sheepshead minnows (Cyprinodon variegatus) and channel catfish (Ictalurus punctatus). A closed-circulating system was designed to maintain up to 100 sheepshead minnows in artificial seawater for longterm exposures. Fish were maintained in this system for up to 31 weeks with weekly contaminations of PAH. Due to their chemical properties significant levels of BaP and MCA remained in the water column for only ca. 24 hours each week and no tumors were observed in the exposed fish during the period of the study. The incidence and types of lesions in control and exposed fish were basically similar except in catfish that were fed PAH contaminated food. High levels of contamination (1 mg/gm food) appeared to be toxic and lower levels of contamination (0.1 mg/gm food) produced sufficient stress to make the catfish susceptible to fatal parasite infestations. Both species accumulated radioactively labelled PAH at concentrations much higher than their nominal concentrations in the water. These results demonstrate that sheepshead minnows function well as experimental organisms in artificial seawater in a closed system maintained at a noncoastal facility. Thus, they provide an excellent model system for the study of longterm effects of chronic exposure to polluting agents.

Includes bibliographical references (pages 29-31).