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  • A S Kolok
  • The American journal of physiology
  • 1992
Winter- and summer-acclimatized largemouth bass (Micropterus salmoides) were collected from hatchery ponds in eastern Colorado during late winter and midsummer, then challenged with two prolonged swimming performances (step test and constant-velocity endurance). Variation in the step test performances was significantly correlated with variation in the(More)
Studies reveal that surface waters worldwide are contaminated with hormonally active agents, many released from sewage treatment plants. Another potential source of aquatic hormonal contamination is livestock feedlot effluent. In this study, we assessed whether feedlot effluent contaminates watercourses by measuring a) total androgenic [methyltrienolone(More)
Over the last decade, research has examined the endocrine-disrupting action of various environmental pollutants, including hormones, pharmaceuticals, and surfactants, in sewage treatment plant effluent. Responding to the growth of concentrated animal feeding operations (CAFOs) and the pollutants present in their wastewater (e.g., nutrients, pharmaceuticals,(More)
The objective of the present study was to determine the occurrence and endocrine effects of agrichemicals in four Nebraska, USA, watersheds--the Elkhorn, Platte, Niobrara, and Dismal rivers. Land use in the Elkhorn River and Platte River watersheds is characterized by intense agriculture, including row crop and beef cattle production. In contrast, land(More)
The goal of the current study was to determine whether sediments from agriculturally intense watersheds can act as a potential source of anti-estrogenic endocrine-disrupting compounds. The specific objectives of the current study were to determine (1) whether female fathead minnows (Pimephales promelas) experience alterations in endocrine function when(More)
Precipitation induced runoff is an important pathway for agrichemicals to enter surface water systems and expose aquatic organisms to endocrine-disrupting compounds such as pesticides and steroid hormones. The objectives of this study were to investigate the distribution of agrichemicals between dissolved and sediment-bound phases during spring pulses of(More)
Previous studies have reported alterations in the endocrine function of fathead minnows (Pimephales promelas) collected and deployed in the Elkhorn River. The goal of the current study was to determine whether sediment from the Elkhorn River watershed could act as a source of endocrine-active compounds. To accomplish this, four aquaria containing sexually(More)
Endocrine disrupting effects in aquatic organisms have been observed in systems influenced by steroid hormones. Associating endocrine disruption with aqueous concentrations of steroids alone may overlook the influence of source-sink dynamics in sediments on steroid hormone bioavailability. The objective of this study was to determine the fate of(More)
Recent studies have detected bioavailable steroids in sediment, however, the mechanism by which these compounds become bioavailable is not completely understood. In this study, two experiments were conducted using a double aquarium system that allowed female fathead minnows to be exposed to sandy sediments without direct contact. In the first experiment,(More)
The caloric density of stomach contents in juvenile chinook salmon,Oncorhynchus tshawytscha, was not affected by gastric evacuation, suggesting a constant caloric density of stomach contents during evacuation. Differences in the caloric density of prey consumed did affect caloric density of stomach contents over a 24-h period. Consumption of the(More)