Reproductive success, xenobiotic contaminants and hepatic mixed-function oxidase (MFO) activity in Platichthys stellatus populations from San Francisco Bay

To identify some specific effects of organic contaminants on fisheries in an urbanized estuary we compared the reproductive success of starry flounder from San Francisco Bay with concentrations of tissue contaminants and hepatic mixed-function oxidase (MFO) activity. We found significantly lower (P < 0·05) sediment concentrations of total identified polynuclear aromatic hydrocarbons (PAHs) in the less urbanized San Pablo Bay (SP) area (Fig. 1) than in the more urbanized central bay (CB) stations (Table 1). For flounder in early gametogenesis (August and September) the SP fish (n = 20) had significantly lower (P < 0·01) liver concentrations of Aroclor 1260 (0·34 ± 0·14 μg/g) than those at the CB stations: Berkeley (BK, n = 20, 1·6 ± 1·6 μg/g); Oakland (OK, n = 16, 2·3 ± 2·8 μg/g); and Alameda (AL, n = 4, 2·2 ± 1 μg/g). A similar pattern existed for DDT concentrations: SP = 0·2 ± 0·16 μg/g; BK = 0·1 ± 0·34 μg/g; OK = 0·4 ± 0·53 μg/g; and AL = 0·4 ± 0·33 μg/g. Total PAHs in livers were as follows: SP = 0·14 μg/g; BK = 2·6 μg/g; OK = 1·4 μg/g; and AL = 14 μg/g. Although gonad index, liver index, and presence of fin rot are inversely related to aryl hydrocarbon hydroxylase (AHH) activity, healthy fish in a similar reproductive state have lower AHH activities in the SP area. For example, in August and September, 1984, mean AHH activities were as follows: SP = 203 ± 89, and CB = 355 ± 200 pmol 3-OH-B[a]P mg microsomal protein min. We found a log-linear relationship for AHH activity and its percent inhibition by 7,8-benzoflavone (10 -4m) and only a few fish from SP showed enhanced AHH activity after addition of 7,8-benzoflavone. This suggests that most of the starry flounder in San Francisco Bay are induced.