Abstract:
Human activities are having a huge impact on the natural world. Global climate change, urbanization, habitat fragmentation, and pollutants are all contributing to rapid and extensive environmental change and posing significant challenges to many species. An anthropogenic impact of growing concern is exposure to a class of contaminants known as endocrine disrupting compounds (EDCs). EDCs are natural or synthetic compounds that interfere in some way with endogenous hormones responsible for maintaining and regulating myriad phenotypic traits. These contaminants enter aquatic environments through agricultural runoff, wastewater treatment plant (WWTP) effluent, and sewage overflow. They have been shown to alter morphology, physiology, and behavior in exposed organisms. Mangrove ecosystems are often retrofitted with WWTPs due to their natural ability to cycle nutrients; however, little is known of how EDC exposure impacts the organisms that inhabit mangroves. The mangrove rivulus fish, Kryptolebias marmoratus, is a mangrove specialist and a suitable organism in which to study the effects of EDC exposure. Here, I use environmentally relevant concentrations of two prevalent EDCs - ethinyl estradiol, the main synthetic estrogen in contraceptive, and nonylphenol, a widespread compound used in plastics and pesticides - to assess how exposure can alter morphology, physiology, and behavior in juvenile and adult mangrove rivulus, in compound-, dose-, and route-specific ways. I also measure the extent to which exposure alters phenotypic variance-covariance structure, which can inform us about how EDCs trigger coordinated changes in many phenotypic traits, and allows us to better assess how anthropogenic activities might induce opportunities for natural selection to act and drive evolutionary change.
