Biomaterial Database

Osmoregulation of the Atlantic stingray (Dasyatis sabina) from the freshwater Lake Jesup of the St. Johns River, Florida. 1998

P M Piermarini, and D H Evans

Department of Zoology, University of Florida, Gainesville 32611, USA.

The goals of this study were to (1) measure plasma osmolytes and rectal gland weights of a freshwater (FW) Atlantic stingray (Dasyatis sabina) population in the St. Johns River, Florida, and (2) determine how these parameters change after acclimation to seawater (SW). We hypothesized that the FW D. sabina may show physiological divergence from marine D. sabina, because the FW individuals reproduce and complete their life cycle in the St. Johns River. The FW D. sabina hyperregulate their plasma osmolality (621.4 mOsm kg(-1)), with plasma Na+, Cl-, and urea concentrations of 211.9, 207.8, and 195.9 mmol L(-1), respectively. FW D. sabina were exposed to 100% SW for 8 d, and their hematocrit did not change significantly compared to control animals left in FW. However, plasma osmolality increased significantly (953 mOsm kg(-1)), with significant increases in plasma concentrations of Na+, Cl-, and urea to 319.13, 296.1, and 329.76 mmol L(-1), respectively. The plasma of the SW-adapted D. sabina was hypo-osmotic and hypoionic to 100% SW. Rectal gland weight to body weight (RGBW) ratios of FW D. sabina were about 80% lower than RGBW ratios reported for marine D. sabina; the RGBW ratio did not increase significantly after SW acclimation. This may indicate that branchial and renal mechanisms are also involved with ion excretion. We conclude that the FW D. sabina are physiologically euryhaline and have not evolved the osmoregulatory strategy of stenohaline FW Potamotrygonid stingrays.

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D004777	Environment	The external elements and conditions which surround, influence, and affect the life and development of an organism or population.	Environmental Impact,Environmental Impacts,Impact, Environmental,Impacts, Environmental,Environments
D005618	Fresh Water	Water containing no significant amounts of salts, such as water from RIVERS and LAKES.	Freshwater,Fresh Waters,Freshwaters,Water, Fresh,Waters, Fresh
D000222	Adaptation, Physiological	The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.	Adaptation, Physiologic,Adaptations, Physiologic,Adaptations, Physiological,Adaptive Plasticity,Phenotypic Plasticity,Physiological Adaptation,Physiologic Adaptation,Physiologic Adaptations,Physiological Adaptations,Plasticity, Adaptive,Plasticity, Phenotypic
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012860	Skates, Fish	The common name for all members of the Rajidae family. Skates and rays are members of the same order (Rajiformes). Skates have weak electric organs.	Raja,Rajidae,Rajiformes,Rays (Fish),Rays, Fish,Skates (Fish),Fish Ray,Fish Rays,Fish Skate,Fish Skates,Ray (Fish),Ray, Fish,Skate (Fish),Skate, Fish
D014508	Urea	A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.	Basodexan,Carbamide,Carmol
D014882	Water-Electrolyte Balance	The balance of fluid in the BODY FLUID COMPARTMENTS; total BODY WATER; BLOOD VOLUME; EXTRACELLULAR SPACE; INTRACELLULAR SPACE, maintained by processes in the body that regulate the intake and excretion of WATER and ELECTROLYTES, particularly SODIUM and POTASSIUM.	Fluid Balance,Electrolyte Balance,Balance, Electrolyte,Balance, Fluid,Balance, Water-Electrolyte,Water Electrolyte Balance