Monitoring xenoestrogen exposure and endocrine disruption in a Puget Sound benthic flatfish, English sole (Parophrys vetulus)

Xenoestrogens, including natural estrogens and synthetic chemicals that mimic estrogens, can disrupt endocrine functions and reproduction in exposed fish. These chemicals are widespread, often entering the environment due to human activities such as industrial discharge, wastewater treatment plant effluents, stormwater or agricultural runoff. Vitellogenin (vtg) is an egg-yolk protein precursor synthesized in the liver of female fish in response to naturally produced estrogens during their normal reproductive cycle. However, vitellogenin can be abnormally induced in male fish if they are exposed to xenoestrogens, making this protein a suitable and widely used biomarker of xenoestrogen exposure. Vitellogenin in English sole is one indicator in the suite of Vital Signs being used by the Puget Sound Partnership to track ecosystem health and recovery. We measured xenoestrogen exposure and biological effects in English sole, a benthic marine flatfish, from twelve monitoring index sites throughout Puget Sound. Steroid estrogens (e.g. estradiol) and estrogen mimics (e.g. bisphenol-A) from the bile of male English sole were used to assess their exposure to environmental estrogens. Plasma vitellogenin occurrence and concentration were measured in male English sole as an indicator of their response to xenoestrogen exposure. Finally, fish of both sexes were analyzed histologically to identify gonadal abnormalities and examine reproductive timing. We observed vitellogenin induction in male English sole throughout central and south Puget Sound, with the highest concentrations of estrogenic chemicals in male bile and vitellogenin in male plasma in fish from Elliott Bay and Carr Inlet. In addition, a portion of female English sole at Elliott Bay and Carr Inlet were in spawning condition outside of the normal spawning period, providing further evidence of endocrine disruption at these locations. We are currently working to expand our endocrine disruption monitoring to additional species including juvenile Chinook salmon and Pacific herring.