Ovarian masculinization and reproductive impairment in 3 species of groundfish in and around the hypoxic zone in the Gulf of Mexico

The results of this study provide additional evidence of ovar-ian masculinization in the Atlantic croaker (Micropogonias undulatus) in and around the hypoxic zone in the Gulf of Mexico and the first evidence of ovarian masculinization in the spot (Leiostomus xanthurus) and bigeye searobin (Prionotus longispinosus). In some specimens of Atlantic croaker and spot, we observed this phenomenon to a degree that has not been reported in either species. We also found evidence of smaller gonads in spot from hypoxic sites compared with the gonads in spot from sites with normal oxygen concen-trations. These findings indicate that ovarian masculinization and repro-ductive impairment associated with hypoxia exposure affect a wider range of species than was previously known, and they highlight the importance of continued research on this topic.