| San Francisco Bay is well documented to be contaminated with several kinds of chemical pollutants. This study's objectives were to determine possible alterations in thyroid endocrine status in two indigenous fish species, the shiner perch (Cymatogaster aggregata) and Pacific staghorn sculpin (Leptocottus armatus), in association with their residence at different SFB locations having distinct types of chemical pollution, and as correlated to accumulated tissue concentrations of specific chemicals within individuals. Significant, site-associated differences were observed in plasma concentrations of thyroxine (T4), triiodothyronine (T3) and T3/T4 ratio, and these differences were associated with locations representing differing types of contamination. Correlation analyses between specific chemicals and thyroid endocrine parameters within individuals elucidated a number of significant correlations, in which some chemicals were associated with depressed T4 and corresponding increases in T3 and/or T3/T4 ratio, and other chemicals having specific effects on T3 and/or T3/T4 ratio. Different possible underlying mechanisms of these thyroid alterations are discussed. |
