Impacts of Wastewater Effluent on Lepomis auritus Reproductive Physiology in Cibolo Creek

Date

2024

Authors

Guajardo, Jesse Ray

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Abstract

Wastewater treatment is essential for community well-being and ensures continuous flow for stream ecosystems during water-stressed periods. However, unregulated hormones and abnormal temperatures in effluent discharge pose risks to receiving water bodies, prompting ecological assessments of aquatic organisms. This study examines the impacts of wastewater effluent pollutants 17-β-estradiol (E2) and 17-α ethinyl-estradiol (EE2) on the reproductive physiology of Lepomis auritus in Cibolo Creek, in Kendall County, Texas. Monthly hepatosomatic index (HSI) and gonadosomatic index (GSI) data were gathered for male and female fish from an effluent-receiving reach and an upstream control reach from February 2023 – January 2024. Female fish were assessed for oocyte diameter and male fish were assessed for vitellogenin proteins (Vtg) using mucosal ELISA analysis. Linear mixed effects models revealed non-significant GSI results between sites across a temporal scale for males. Male Vtg was detected in only one L. auritus individual from the test site. Together, these results indicate weak estrogenic effects. HSI was higher at the test site, potentially impacted by pollutants or warmer water temperature from effluent from October 2023 through January 2024. Smaller oocyte diameter at the test site suggests potential impact from the same factors. Despite minimal impact on male GSI, the known presence of E2 and EE2 at the test site, the small GSI for females, the enlargement of hepatosomatic index (HSI), reduced oocyte sizes, and the detection of male vitellogenin (Vtg) in 1 out of 11 males at the test site indicate impacts of wastewater effluent on some aspects of fish physiology.

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Environmental Science