Previous studies have demonstrated that mummichogs (Fundulus heteroclitus) collected from Piles Creek (PC), New Jersey, USA (a site polluted with heavy metals and organic materials), were sluggish and showed poorer prey capture and predator avoidance than those from a reference site (Tuckerton [TK], NJ, USA). We hypothesized that the behavioral dysfunction of the PC fish might be associated with thyroid impairment due to toxic exposures. In this preliminary study, we compared thyroid histology and thyroid hormones in the two populations and experimentally determined whether a polluted or an unpolluted environment could alter levels of thyroid hormones. In comparison to TK, PC fish had larger thyroid follicles and greater follicle epithelial cell heights and also contained significantly higher plasma thyroxine (T4) levels. However, no significant differences were found in levels of either plasma or tissue triiodothyronine (T3). The TK fish raised in a simulated PC environment contained higher plasma T4 and lower plasma T3 levels than those sampled from the field. The PC fish raised in clean water showed a reduction in both plasma T4 and T3 levels in comparison to field-sampled fish. In either case, no significant difference was found tissue T3 content. The contaminants in PC may cause the differences in thyroid structure and function, which may be partly responsible for the behavioral differences between fish from the polluted PC and from the reference TK.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Health, Toxicology and Mutagenesis
- Endocrine disruptors
- Fundulus heteroclitus