Endocrine disrupting effects on creek chubs (Semotilus atromaculatus) exposed to agricultural contaminants in the Cedar Creek watershed, northeast Indiana

Daragh J Deegan, Purdue University

Abstract

Current research that has been performed suggests that agricultural contaminants are potential endocrine disrupters. However, there has been a lack of field studies performed that assesses the endocrine disrupting impacts of synergistic mixes of agrichemicals on wild fishes. Creek chubs (Semotilus atromaculatus ) were collected from four agricultural drainage ditch sites on two occasions (May and June) of 2008. Based on similarities in concentrations of agrichemicals, two treatment groups were made; high-impact sites (HIS) and low-impact sites (LIS). Chubs were also collected from one reference headwater stream. It was hypothesized that male creek chubs inhabiting sites with the greatest concentrations of agrichemicals would show greater gene expression of vitellogenin and aromatase and demonstrate other indicators of endocrine disruption. Relative expression of CYP19 in male and unknown gender chubs did not differ significantly among sites, but was significantly lower in females at the HIS compared to the LIS and the reference site. Relative expression of VTG in females, males, and unknowns did not differ significantly among sites. HCT values in male and unknown gender fish did not differ significantly among sites, but HCT values in females were significantly higher at the HIS compared to the reference site. LSI values in females, males, and unknowns did not differ significantly among sites. Four intersex chubs were collected from the HIS and one was collected from the LIS. Other gonad abnormalities were observed at all sites, and a high proportion of fish collected during the May sample had gonads that were too small to be observed histologically. The collection of 4 intersex creek chubs, and in the inhibition of CYP19 in females at sites with the highest concentration of agricultural contaminants, suggest that agrichemicals may cause endocrine disruption in female creek chubs.

Degree

M.S.

Advisors

Gillespie, Purdue University.

Subject Area

Endocrinology|Physiology

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