Extensive reproductive disruption, ovarian masculinization and aromatase suppression in Atlantic croaker in the northern Gulf of Mexico hypoxic zone
نویسندگان
چکیده
The long-term impacts on marine ecosystems of the recent dramatic worldwide increase in the incidence of coastal hypoxia are unknown. Here, we show widespread reproductive disruption in Atlantic croakers collected from hypoxic sites approximately 120 km apart in the extensive northern Gulf of Mexico continental shelf hypoxic zone. Gonadal growth and gamete production were impaired in croakers from hypoxic sites compared with fish from reference normoxic sites east of the Mississippi River Delta. Male germ cells were detected in approximately 19 per cent of croaker ovaries collected in the hypoxic region, but were absent in ovaries from normoxic sites. In addition, the sex ratio was skewed towards males at the hypoxic sites. The masculinization and other reproductive disruptions were associated with declines in neuroendocrine function, as well as ovarian and brain expression of aromatase (the enzyme that converts androgens to oestrogens). A similar incidence of ovarian masculinization and decline in ovarian aromatase expression were observed in croaker after chronic laboratory hypoxia exposure, indicating that ovarian masculinization is a specific hypoxia response and is due to decreased aromatase activity. The results suggest severe reproductive impairment can occur over large coastal regions in marine fish populations exposed to seasonal hypoxia, with potential long-term impacts on population abundance.
منابع مشابه
Molecular and biochemical responses of hypoxia exposure in Atlantic croaker collected from hypoxic regions in the northern Gulf of Mexico
A major impact of global climate change has been the marked increase worldwide in the incidence of coastal hypoxia (dissolved oxygen, DO<2.0 mg l-1). However, the extent of hypoxia exposure to motile animals such as fish collected from hypoxic waters as well as their molecular and physiological responses to environmental hypoxia exposure are largely unknown. A suite of potential hypoxia exposur...
متن کاملReproductive endocrine dysfunction in Atlantic croaker exposed to hypoxia.
Although there is extensive evidence for impaired endocrine function in fishes exposed to environmental chemicals, information is currently lacking on reproductive endocrine effects of other environmental stressors such as hypoxia. The effects of ten weeks exposure to low dissolved oxygen (DO: 2.7 ppm and 1.7 ppm) on reproductive morphometric and endocrine responses in female Atlantic croaker (...
متن کاملFood of the Atlantic Croaker, Micropogonias undulatus, from Mississippi Sound and the Gulf of Mexico
lhe diet of the Atlantic croaker from Mississippi Sound has been examined for the f i s t time. Over 83 taxa were encountered, or more than were reported from croaker in any other region. We also found 60 taxa, 36 of which overlapped with the above, in croaker from various offshore stations in the Gulf of Mexico. In Mississippi Sound the frequency of occurrcnce of items revealed primarily crust...
متن کاملWidespread endocrine disruption and reproductive impairment in an estuarine fish population exposed to seasonal hypoxia.
The long-term effects on marine fish populations of the recent increase worldwide in the incidence of coastal hypoxia are unknown. Here we show that chronic environmental exposure of Atlantic croaker (Micropogonias undulatus) to hypoxia in a Florida estuary caused marked suppression of ovarian and testicular growth which was accompanied by endocrine disruption. Laboratory hypoxia studies showed...
متن کاملAromatase activity in the ovary and brain of the eastern mosquitofish (Gambusia holbrooki) exposed to paper mill effluent.
Studies have shown that female mosquitofish living downstream of a paper mill located on the Fenholloway River, Florida, have masculinized secondary sex characteristics, including altered anal fin development and reproductive behavior. Masculinization can be caused by exposure to androgens in the water or from an alteration in aromatase activity in the fish. We hypothesized that aromatase activ...
متن کامل