Widespread 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 t...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2007-11, Vol.274 (1626), p.2693-2702
Main Authors: Thomas, Peter, Rahman, Md. Saydur, Khan, Izhar A, Kummer, James A
Format: Article
Language:English
Subjects:
Animal reproduction
Animals
Brackish
Ecosystem
Endocrine Disruption
Estuaries
Estuary
Female
Fish
Gametogenesis
Gonadotropin-Releasing Hormone
Hydroxyindoleacetic Acid
Hypoxia
Luteinizing Hormone
Male
Marine
Marine fishes
Materials
Messenger RNA
Micropogonias undulatus
Neuroendocrine Mechanism
Oocytes
Ovary - growth & development
Ovulation
Perciformes - physiology
Reproduction
Reproduction - physiology
RNA, Messenger
Seasons
Serotonin - metabolism
Serotonin receptors
Spermatogenesis
Spermatozoa
Testis - growth & development
Tryptophan Hydroxylase
Water - chemistry
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Summary: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 that the endocrine disruption was associated with impairment of reproductive neuroendocrine function and decreases in hypothalamic serotonin (5-HT) content and the activity of the 5-HT biosynthetic enzyme, tryptophan hydroxylase. Pharmacological restoration of hypothalamic 5-HT levels also restored neuroendocrine function, indicating that the stimulatory serotonergic neuroendocrine pathway is a major site of hypoxia-induced inhibition. Inhibition of tryptophan hydroxylase activity to downregulate reproductive activity could have evolved as an adaptive mechanism to survive periodic hypoxia, but in view of the recent increased incidence of coastal hypoxia could become maladaptive and potentially affect fish population abundance and threaten valuable fishery resources.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2007.0921