Darren T. Lerner

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Over a 2-yr period, we investigated the annual cycles of plasma testosterone and corticosterone and the relationships between these hormones and body condition in a wild population of male red-spotted garter snakes, Thamnophis sirtalis concinnus. In the 10 mo that were sampled, a peak in testosterone was observed in late summer during gametogenesis and(More)
Sex steroids are known to interfere with the parr-smolt transformation of anadromous salmonids, and environmental estrogens such as nonylphenol have recently been implicated in reduced returns of Atlantic salmon in the wild. To determine the endocrine pathways by which estrogenic compounds affect smolt development and seawater tolerance, groups of juvenile(More)
Population declines of wild Atlantic salmon have been attributed to an array of anthropogenic disturbances, including dams, commercial and recreational fishing, habitat loss, and pollution. Environmental contaminants in particular, can act as environmental stressors on fish, typically causing disruption of ion homeostasis due to their close association with(More)
Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon(More)
Polychlorinated biphenyls (PCBs) are a widespread aquatic contaminant and are present in both wild and hatchery raised Atlantic salmon, Salmo salar. The possible sub-lethal alterations in smolt physiology and behavior due to PCB exposure of salmon have not been widely examined. In this study, we examined the effects of the PCB mixture Aroclor 1254 on(More)
Introduced species are an increasingly pervasive problem. While studies on the ecology and behavior of these pests are numerous, there is relatively little known of their physiology, specifically their reproductive and stress physiology. One of the best documented introduced pest species is the brown tree snake, Boiga irregularis, which was introduced onto(More)
Polychlorinated biphenyls (PCBs) exist as persistent organic pollutants in numerous river systems in the United States. Unfortunately, some of these rivers are sites of active Atlantic salmon restoration programs, and polychlorinated biphenyls have been implicated as ancillary factors contributing to failed salmon restoration. Here, we investigate the(More)
The red-spotted garter snake exhibits adult size dimorphism in which females are the larger sex. To understand which hormones may influence differential growth in this species, growth curves and hormone profiles of estradiol-17beta (E2) and testosterone (T) were constructed in male and female neonates. Growth was manipulated via implantation of exogenous(More)
Exposure of Atlantic salmon smolts to estrogenic compounds is shown to compromise several aspects of smolt development. We sought to determine the underlying endocrine mechanisms of estrogen impacts on the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. Smolts in freshwater (FW) were either injected 3 times over 10 days with 2 μgg(-1)(More)
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