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Freshwater to seawater transitions in migratory fishes

January 1, 2012

The transition from freshwater to seawater is integral to the life history of many fishes. Diverse migratory fishes express anadromous, catadromous, and amphidromous life histories, while others make incomplete transits between freshwater and seawater. The physiological mechanisms of osmoregulation are widely conserved among phylogenetically diverse species. Diadromous fishes moving between freshwater and seawater develop osmoregulatory mechanisms for different environmental salinities. Freshwater to seawater transition involves hormonally mediated changes in gill ionocytes and the transport proteins associated with hypoosmoregulation, increased seawater ingestion and water absorption in the intestine, and reduced urinary water losses. Fishes attain salinity tolerance through early development, gradual acclimation, or environmentally or developmentally cued adaptations. This chapter describes adaptations in diverse taxa and the effects of salinity on growth. Identifying common strategies in diadromous fishes moving between freshwater and seawater will reveal the ecological and physiological basis for maintaining homeostasis in different salinities, and inform efforts to conserve and manage migratory euryhaline fishes.

Publication Year 2012
Title Freshwater to seawater transitions in migratory fishes
DOI 10.1016/B978-0-12-396951-4.00006-2
Authors Joseph D. Zydlewski, Michael P. Wilkie
Publication Type Book Chapter
Publication Subtype Book Chapter
Index ID 70174110
Record Source USGS Publications Warehouse
USGS Organization Coop Res Unit Leetown