Do Laboratory Species Protect Endangered Species? Interspecies Variation in Responses to 17β-Estradiol, a Model Endocrine Active Compound

Abstract

Although the effects of estrogens on model laboratory species are well documented, their utility as surrogates for other species, including those listed as endangered, are less clear. Traditionally, conservation policies are evaluated based on model organism responses but are intended to protect all species in an environment. We tested the hypothesis that the endangered Rio Grande silvery minnow (Hybognathus amarus) is more vulnerable to endocrine disruption-as assessed through its larval predator-escape performance, survival, juvenile sex ratios, and whole-body vitellogenin concentration-than the commonly used toxicological model species fathead minnow (Pimephales promelas) and the bluegill sunfish (Lepomis macrochirus). Fish were exposed concurrently for 21 days to the model endocrine active compound (EAC) 17ß-estradiol (E2) at 10 ng E2/L and 30 ng E2/L in a flow-through system using reconstituted water that simulated the physicochemical conditions of the Middle Rio Grande in New Mexico, USA. No significant differences were observed between the fathead and silvery minnow in larval predator-escape response or juvenile sex ratio. Rio Grande silvery minnow survival decreased significantly at day 14 compared with the other two species; by day 21, both cyprinid species (silvery minnow and fathead minnow) exhibited a significant decrease in survival compared with bluegill sunfish, a member of the family Centrarchidae. Male Rio Grande silvery minnow showed a significant increase in whole-body vitellogenin concentration in the 10 ng/L treatment, whereas fathead minnow and bluegill sunfish showed no significant increases in vitellogenin concentrations across treatments. Our study showed response differences to estrogen exposures between the two cyprinid species and further divergence in responses between the families Cyprinidae and Centrarchidae. These results suggest that commonly used laboratory model organisms may be less sensitive to EACs than the endangered Rio Grande silvery minnow. However, this study supports the continued use of surrogate species for the beneficial implementation of water-quality regulations for the protection of threatened and endangered species if phylogenetic relationships are taken into consideration.

Uptake and Disposition of Select Pharmaceuticals by Bluegill Exposed at Constant Concentrations in a Flow-Through Aquatic Exposure System

“…In this study, bluegill sunfish was selected as the model species because it is a common species in freshwater environments throughout North America and has been used for exposure both in laboratory and in field studies . Experiments were conducted in a flow-through system previously used for other studies .…”

“…In this study, bluegill sunfish was selected as the model species because it is a common species in freshwater environments throughout North America and has been used for exposure both in laboratory and in field studies. 52 Experiments were conducted in a flow-through system previously used for other studies. 53 Juvenile bluegill (15−20 g) were purchased from a commercial hatchery (10 000 Lakes Aquaculture, Osakis, MN, U.S.A.) and allowed to acclimatize to laboratory conditions at least 1 week prior to use.…”

Divergent responsiveness of two isoforms of the estrogen receptor to mixtures of contaminants of emerging concern in four vertebrates

“…However, their effects as complex, environmentally relevant mixtures are poorly understood across vertebrate phylogeny. A wide variety of wildlife, including listed (e.g., threatened or endangered) species, have been experimentally exposed to CECs, and the consequences of exposures to reproductive function have been documented in various species including teleost fishes (Clement, Reiner, & Bhavsar, ; Jorgenson, Buhl, Bartell, & Schoenfuss, ; Newsted et al, ; Stahl et al, ), American alligators (Bangma et al, ) and humans (Casas et al, ; D’Hollander, de Voogt, De Coen, & Bervoets, ). Although it has been documented that species are being exposed and have the potential to bioaccumulate CECs, information is limited relating exposure to effects in wildlife, particularly listed species.…”

Reference Species

“…Because findings on reference species tested in laboratories are often extrapolated with the attempt to protect endangered and threatened species, Jorgenson et al (2014) have tested the model endocrine active compound 17 β-estradiol (E2) on two cyprinids (the endangered Rio Grande silvery minnow and the fathead minnow, commonly used in bioassays), both species being found in the Middle Rio Grande. They have also assessed exposure effects in bluegill sunfish, a centrarchid sometimes used in field studies, and phylogenetically distant from cyprinids.…”