Interspecies differences in biochemical, histopathological, and population responses in four wild fish species exposed to ethynylestradiol added to a whole lakeThis paper is part of the series Forty Years of Aquatic Research at the Experimental Lakes Area.

Efforts to understand the effects of environmental estrogens on fish have shifted away from biochemical indicators towards population-level impacts. Ethynylestradiol (EE2) was added to a whole lake at environmentally relevant concentrations for 3 consecutive years to examine links between vitellogenin (VTG) induction, histopathological impacts, and population decline in four species of fish. VTG induction and histopathological effects in tissues were most severe in fathead minnow ( Pimephales promelas ) and pearl dace ( Margariscus margarita ). VTG was induced to a similar extent in lake trout ( Salvelinus namaycush ) but less so in white sucker ( Catostomus commersonii ). There were no histopathological effects in tissues of the two latter species. Population decline occurred in fathead minnows in the second year of EE2 additions and there were some indications of population decline in pearl dace during the third year. White suckers were not affected but lake trout declined in year 3. Habitat selection probably altered EE2 exposure and the different effects in each species likely also reflect differing sensitivities. It appears that VTG induction is not sufficient to predict effects of xenoestrogens on fish populations. However, stronger predictions can be made when VTG induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage.