Diel hypoxia in marsh creeks impairs the reproductive capacity of estuarine fish populations.

The article presents a field study which assesses the impact of diel hypoxia in the reproductive capacity of estuarine fishes captured in Alabama and Florida. The method of the study employs the acetylcholinesterase-based competitive enzyme-linked immunosorbent assay (ELISA) to analyze the hormones and vitellogenin (VTG) of sampled gulf killifish Fundulus grandis coming from sites with different dissolved oxygen cycles and different rate of diel hypoxia. It also analyzes the differences in condition factor, relative gonad size, steroid sex hormones and VTG via stepwise forward regression statistics. The result shows that testes and ovaries of gulf killifish coming from the site with severe and moderate diel hypoxia are significantly smaller.