Fitness in novel environments: Bisphenol S and warming reduce energy efficiency, reproductive success, and movement across generations in zebrafish (Danio rerio).

Natural environments today differ from those in the recent past because of altered abiotic conditions and the presence of endocrine disrupting compounds that modify responses to those conditions. We aimed to quantify the interactive effects of temperature and an emerging endocrine disrupting compound (bisphenol S [BPS]) on physiology and reproduction within and across generations of zebrafish (Danio rerio). We conducted a fully factorial experiment with temperature (24 and 30 °C) and BPS (control and 10μ g l-1) as factors. In the directly exposed parental F0 generation increased temperature and BPS decreased energy efficiency of locomotion (increased cost of transport), and clutch size decreased with increasing cost of transport indicating a shift in energy allocation. In the F0 and their unexposed offspring F1 generations, there were parallel decreases in locomotor performance, and fertilisation rate (F0) following (parental) BPS exposure. Similarly, survival of offspring from both generations was lowest in fish whose (grand)parents were treated with BPS at 30 °C. These parallel responses indicate cross-generational, epigenetic effects. Dispersal success of F1 fish decreased with increasingly challenging flow conditions in an artificial stream, and BPS exposure reduced dispersal success at 24 °C. Warming and BPS-mediated reductions in reproductive success combined with decreased offspring survival is likely to reduce populations sizes, which together with reduced dispersal can limit gene flow in meta-populations. It is important to incorporate data from physiological experiments into assessing the ecological impacts of novel environments to develop the most effective conservation strategies.