Altered endocrine physiology of marine flatfish associated with Southern California wastewater treatment plant (WWTP) outfalls: Stress, growth and reproduction

The Southern California Bight (SCB) receives over 1 billion gallons of treated wastewater per day generated by > 20 million persons and their activities. This Thesis study undertook an initial investigation of resident wild flatfish, including English sole (Parophrys vetulus) and hornyhead turbot (Pleuronichthys verticalis), and potential alterations in their endocrine systems occurring in association with environments impacted by wastewater treatment plants (WWTPs). Fish from affected environments were found to be incapable of producing normal surges in the stress hormone, cortisol, in response to stress. They also exhibited reductions in plasma levels of the growth-promoting peptide, insulin-like growth factor-I. In addition, in locations receiving the largest volumes of WWTP effluents, hornyhead turbot of both sexes exhibited elevated levels of the sex steroid, 17beta-estradiol. In conclusion, wild flatfish in the SCB appear to exhibit disruption of at least three essential endocrine systems when residing in environments impacted by WWTP outfalls.