Exposure to sublethal levels of waterborne lead alters reproductive behavior patterns in fathead minnows (Pimephales promelas).

Lead (Pb) caused multiple effects on reproductive behavior and overall reproductive success. Adult fathead minnows (Pimephales promelas) were acclimated at a 16L:8D photoperiod to stimulate reproductive development. Reproductively mature adults were separated as male-female pairs and maintained for 4 weeks in either 0.0 or 0.5 ppm Pb. High lead accumulations occurred in testes and ovaries of treated fish; lead concentrations in control fish gonads were not detectable. Lead suppressed spermatocyte production and retarded ovarian development, although no lead-induced gonadosomatic index changes for either sex were noted. Lead decreased the number of eggs oviposited, increased interspawn periods and suppressed embryo development. Control males displayed maximum secondary sex characteristic development (banding, tubercle formation, head and eye darkening); lead-exposed fish displayed less. Control males spent more time in ceiling-directed behaviors associated with nest preparation and maintenance than lead-exposed. These variables were affected differentially with respect to stage of reproductive maturity at time of lead exposure, i.e., fish displaying greater secondary sex characteristic development before exposure were less affected by lead than those fish that showed less development.