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ASSESSING THE EFFECTS OF HYPOXIA ON FISH POPULATION ECOLOGY USING ELEMENTS AND ISOTOPES
Impact/Purpose:
The objectives of this research are to use fish otolith (earstone) chemistry as a natural chronological indicator of hypoxia exposure, and investigate links between exposure history, fish performance and trophic dynamics in the seasonally hypoxic northern Gulf of Mexico. Specific research questions include: Does the redox-sensitive element manganese (Mn) get released from the sediment during hypoxic conditions and become incorporated into fish otoliths, offering a proxy of exposure? Does hypoxic exposure alter fish growth rates, conditions and trophic interactions?
Description:
Linking hypoxic exposure to trophic dynamics of Atlantic croaker, an abundant fish and integral component in Gulf of Mexico food webs, will provide information on ecosystem structure and functioning in response to seasonal hypoxia. Additionally, validating a natural permanent chronological recorder of hypoxia in fish will allow new hypotheses to be tested regarding historic hypoxic episodes by examining archived otoliths of other species and in other ecosystems across the world.
Potential to Further Environmental/Human Health Protection
Hypoxia is one of many stressors that threaten the sustainability of valuable ecosystem services provided by estuarine and coastal regions across the United States and world. Understanding the sub-lethal populationwide effects of hypoxia, such as reduced individual fitness and altered trophic structure of ecologically and economically important fish species, is necessary to improve objectives of environmental policy and enhance resource protection measures.