Effects of synthetic estrogen (17α-ethynylestradiol) on spawning in the aggregating anemone, Anthopleura elegantissima, and density and photosynthetic performance of its zooxanthellae symbiont, Breviolum muscatinei

The effect of estrogenic pollutants on wildlife is a growing concern. Synthetic estrogen, 17α-ethynylestradiol (EE2), is a potent estrogenic pollutant used in birth control that originates in wastewater and ends up in receiving surface waters where it can accumulate in sediments and aquatic organisms. EE2 can reduce growth, gametogenesis, semen quality, fecundity, and embryo viability and promote feminization and skewed sex ratios among different aquatic organisms. Most research on EE2 impacting aquatic life has focused on fish, with less attention paid to invertebrates and algae. We examine the effect of environmentally relevant concentrations of EE2 (0, 1.5, 15, and 150 ng/l) on spawning in males of the aggregating anemone, Anthopleura elegantissima, and density and photosynthetic performance of its zooxanthellae symbiont, Breviolum muscatinei. Exposure to 150 ng/l EE2 significantly increased chlorophyll a content per zooxanthellae cell and photosynthetic efficiency (Fv/Fm) of Photosystem II compared to the negative control. Symbiont density was not significantly associated with EE2 concentration, whereas host clonality was significantly associated. Lastly, EE2 concentration was a significant predictor of whether anemones spawned after being induced. This is the first study to our knowledge to examine the impact of EE2 exposure on anemone spawning and zooxanthellae density and photosynthetic performance.