There is increasing concern that certain chemicals in the aquatic environment can disrupt endocrine systems, leading to reproductive impairment and threatening survival of wild populations of invertebrates, fish, bird, reptiles, and wildlife. For the first time, we report that hypoxia is also an endocrine disruptor and poses a significant threat to the reproduction and hence sustainability of fish populations. Serum levels of testosterone, estradiol, and triiodothyronine significantly decreased in carp (Cyprinus carpio) upon chronic exposure to hypoxia. These hormonal changes were associated with retarded gonadal development in both male and female carp, reduced spawning success, sperm motility, fertilization success, hatching rate, and larval survival, indicating that adverse effects of hypoxia on reproductive performance resulted from endocrine disruption. Since aquatic hypoxia commonly occurs over thousands of square kilometers in aquatic systems worldwide, our results imply that endocrine disruption and reproductive impairment in fish may be a widespread environmental problem.
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http://dx.doi.org/10.1021/es0258327 | DOI Listing |
Comp Biochem Physiol A Mol Integr Physiol
January 2025
Department of Biology, University of Ottawa, K1N6N5, 20 Marie Curie, Ottawa, ON, Canada. Electronic address:
The occurrence of environmental hypoxia in freshwater and marine aquatic systems has increased over the last century and is predicted to further increase with climate change. As members of the largest extant vertebrate group, freshwater fishes, and to a much lesser extent marine fishes, are vulnerable to increased occurrence of hypoxia. This is important as fishes render important ecosystem services and have important cultural and economic roles.
View Article and Find Full Text PDFMov Ecol
January 2025
Great Lakes Laboratory for Fisheries and Aquatic Science, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, ON, Canada.
Background: Globally, temperate lakes are experiencing increases in surface water temperatures, extended periods of summer stratification, and decreases of both surface and deep water dissolved oxygen (DO). The distribution of fish is influenced by a variety of factors, but water temperature and dissolved oxygen are known to be particularly constraining such that with climate change, fish will likely feel the "squeeze" from above and below.
Methods: This study used acoustic telemetry to explore the effects of both thermal stratification and the deoxygenation of the hypolimnion on walleye (Sander vitreus) movements in a coastal embayment in Lake Ontario.
Comp Biochem Physiol A Mol Integr Physiol
January 2025
Beijing Normal University, Beijing 100875, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Science, Beijing 100012, China.
The prevalence of heatwave and hypoxia events and their devastating impacts on aquatic ecosystems and fishery resources reinforces the priority of research to address the resilience and adaption mechanisms to these two stressors in important fish species. However, our understanding of the development of cross-tolerance of these two stressors in fish still limited. Here, we investigated the impacts of prior heatwave exposure on hypoxia tolerance and the underlying mechanisms in silver carp (Hypophthalmichthys molitrix), a species of considerable ecological and commercial importance.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA.
Hypoxia tolerance and its variation with temperature, activity, and body mass, are critical ecophysiological traits through which climate impacts marine ectotherms. To date, experimental determination of these traits is limited to a small subset of modern species. We leverage the close coupling of carbon and oxygen in animal metabolism to mechanistically relate these traits to the carbon isotopes in fish otoliths (δC).
View Article and Find Full Text PDFFish Physiol Biochem
February 2025
Department of Biological Sciences, University of North Texas, Denton, TX, USA.
Ventilation frequencies of the gills (f) and the air-breathing organ (f) were measured in juveniles and adults of the air-breathing betta (Betta splendens) and the blue gourami (Trichopodus trichopterus) in response to temperature and hypoxia. Ventilatory rates were evaluated after 1 h of exposure to 27 °C (control), 23 and 31 °C (PO = 21.0 kPa), after acute temperature changes (ATC) from 23 to 27, and 27 to 31 °C, and under progressive hypoxia (PH; PO = ~ 21 to 2.
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