LANDRY, CA; MANNING, S; CHEEK, AO; Southeastern Louisiana University, Hammond; Gulf Coast Research Laboratory, Ocean Springs; Southeastern Louisiana University, Hammond: Hypoxia Affects Reproduction in Gulf Killifish, Fundulus grandis

Hypoxia is a naturally occurring consideration of water quality. The longevity and range of low dissolved oxygen occurrences can be exacerbated by eutrophication, now listed as a water quality concern by the United States Environmental Protection Agency for Gulf of Mexico Estuaries. Chronic hypoxia has been shown to cause disturbances in the regulation of endocrine systems in teleost fish. A controlled laboratory study was performed to focus on the effects of low dissolved oxygen on the reproductive capacity of Fundulus grandis, the Gulf killifish. Serum hormone levels of 11-ketotestosterone were significantly lower in hypoxic males, while serum testosterone levels tended to be lower in hypoxic males when compared to male fish kept under normoxic conditions. Females kept under hypoxic conditions showed significantly lower numbers of ovulated/spawned eggs than controls with trends toward lower levels of serum estrogen. These results are suggestive that under chronic hypoxic conditions, the fish are more likely to focus on metabolic processes necessary for survival rather than reproduction.