Common carp (Cyprinus carpio) is a commercially and recreationally important species that has declined by > 80% across the Illinois River basin since the 1960s, suggesting impairment of population-level reproduction. Numerous controlled experiments have shown common carp reproductive physiology is susceptible to endocrine-disrupting chemical (EDC) exposure at levels commonly associated with the urban and agricultural reaches of this large river. The aim of our study was to investigate spatial patterns of potential physiological and reproductive impairment in common carp related to basin-scale differences in land use. There were complex sex-specific differences in the spatial patterns of several biomarkers we examined from common carp in the Illinois River, suggesting common carp may be exhibiting physiological effects related to EDCs and other contaminants. Biomarkers in female common carp showed little spatial variation along the Illinois River, whereas multiple biomarkers in male common carp indicated a spatially variable response. However, the low prevalence of intersex condition in male common carp contrasts with centrarchid species from the same system, perhaps because of differences in trophic position, habitat use, or physiology. This same low prevalence of intersex may preclude the utility of blood plasma vitellogenin as a nonlethal indicator of intersex in male common carp. Ultimately, despite the evidence of intersex in largemouth bass and black crappie from the Illinois River, we conclude that it is unlikely that EDC exposure leading to intersex condition is contributing to the declining common carp population in this river.

鲤鱼 ( Cyprinus carpio) 是一种重要的商业和娱乐性物种，自 1960 年代以来，伊利诺伊河流域的物种数量下降了 > 80%，表明种群水平繁殖受到损害。大量对照实验表明，鲤鱼的生殖生理学容易受到内分泌干扰化学物质 (EDC) 的影响，其暴露水平通常与这条大河的城市和农业河段相关。我们研究的目的是调查与流域尺度土地利用差异相关的鲤鱼潜在生理和繁殖障碍的空间模式。我们从伊利诺伊河的鲤鱼身上检查的几种生物标志物的空间模式存在复杂的性别特异性差异，这表明鲤鱼可能表现出与 EDC 和其他污染物相关的生理效应。雌性鲤鱼的生物标志物在伊利诺伊河沿岸几乎没有空间变化，而雄性鲤鱼的多种生物标志物表明空间变化响应。然而，雄性鲤鱼双性病的低流行率与来自同一系统的中心鱼形成鲜明对比，这可能是因为营养位置、栖息地使用或生理学的差异。雌雄同体的同样低流行率可能会排除血浆卵黄蛋白原作为雄性鲤鱼雌雄异体的非致死指标的应用。最终，尽管伊利诺伊河的大口黑鲈和黑鲈鱼存在双性的证据，但我们得出的结论是，导致双性条件的 EDC 暴露不太可能导致这条河中鲤鱼数量的下降。