Osmoregulation in the Sheepshead Minnow, Cyprinodon variegatus: Influence of a Fluctuating Salinity Regime

• Published in: Estuaries Vol. 22; no. 4; pp. 1071 - 1077
• Main Author: Haney, Dennis C.
• Format: Journal Article
• Language: English
• Published: Lawrence, KS Estuarine Research Federation 01.12.1999; Springer Nature B.V
• Subjects: Aquaculture; Atlantic Ocean; Biochemistry; Biological and medical sciences; Blood plasma; Brackish; Chlorides; Cyprinodon variegatus; Estuaries; Experimentation; Fish; Fundamental and applied biological sciences. Psychology; Hematocrit; Marine; Marine fishes; Metabolisms and neurohumoral controls; Mexico Gulf; Osmoregulation; Osmosis; Physiological regulation; Physiology; Plasma; Salinity; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water and mineral metabolism. Osmoregulation. Acidobasic balance; Gulf of Mexico; ASW, USA, Florida; Brackish water environment; Salt marsh; Vertebrata; Osmolarity; Cyprinodon variegatus; Pisces; Osmoregulation; Environmental factor; Hematocrite; Dose activity relation; Salinity
• ISSN: 0160-8347; 1559-2723; 1559-2758; 1559-2731
• DOI: 10.2307/1353084

Cyprinodon variegatus (sheepshead minnow), a common coastal resident of the western Atlantic Ocean and Gulf of Mexico, can live in ambient salinities ranging from 0‰ to greater than 140‰. Fish in this study were obtained from a Gulf of Mexico salt marsh near Cedar Key, Florida. This study examined the ability of individual C. variegatus to regulate plasma osmolality under the influence of a cycling salinity regime. Individuals of C. variegatus were exposed for 21 d to one of seven cyclical salinity regimes. Each cycle lasted for 2 d, with salinity varied between 10‰ and 30‰ each day. Plasma osmolality of fish from each group was determined on five dates during the course of the experiment. C. variegatus efficiently regulated plasma osmolality, even when fishes were exposed to large fluctuations in salinity. Fish previously exposed to large salinity fluctuations regulated plasma osmolality better than fish that previously had experienced no change or small changes in salinity. Increasing salinity had a greater impact on osmoregulation than did decreasing salinity.