Assessment of gonadal and thyroid histology in Gulf killifish (Fundulus grandis) from Barataria Bay Louisiana one year after the Deepwater Horizon oil spill

We examined gonads and thyroid glands of Gulf killifish (Fundulus grandis) 1 yr after the Deepwater Horizon oil spill. F. grandis were trapped from two impacted sites in Barataria Bay (Bayou St. Denis, Bay Jimmy) and an un-impacted site in East Texas (Sabine Pass). The greatest number of F. grandis were collected at Sabine Pass. F. grandis collected at Bayou St. Denis were smaller and had smaller Fulton condition factor scores than fish collected at Sabine Pass. Sex ratios were biased roughly 2:1 in favor of females at Sabine Pass and Bayou St. Denis. Gonad-somatic index (GSI) in males from Sabine Pass was double that of fish from Bay Jimmy while germinal epithelium thickness of the testes was 2.7 fold smaller in males from the impacted site. GSI and oocyte diameters in females from Bayou St. Denis were significantly smaller than females from Bay Jimmy or the reference site. There were no differences in thyroid follicle cell height. While total polyaromatic hydrocarbons at the impacted sites were no different from the reference site, the impacted sites did have greater concentrations of benzo[a] pyrene in sediment pore water. The finding of smaller GSI and testicular germinal epithelium in males from an impacted site suggest that exposure to a combination of oil and dispersants may adversely impact testicular function.