UBC Theses and Dissertations
Aspects of ionic regulation in Cancer magister, dana. Engelhardt, Frank Rainer
Regulation of chloride, sodium, potassium, calcium, and magnesium ions was determined for hypo- and hypersaline conditions in the crab, Cancer magister, from an estuarine environment. Animals from both summer and winter were examined. Chloride regulation in the blood was hypertonic in dilute salinities and hypotonic in concentrated salinities, with summer animals maintaining a greater gradient in the former and winter animals a greater gradient in the latter. Sodium in the blood is regulated hypertonically in all experimental salinities, with summer animals maintaining a greater gradient. Blood potassium is regulated hypertonically in dilute salinities, approaching isotonicity in hypersaline media. Summer animals maintain a greater gradient of potassium concentration. Blood calcium is regulated hypertonically in all experimental salinities, with summer animals maintaining a greater gradient in dilute salinities and winter animals a greater gradient in concentrated salinities. Magnesium is regulated at a pronounced hypotonic level in the blood over the entire experimental salinity range, with winter animals maintaining the greater gradient. Major changes in the adaptation of blood ionic concentrations occur within a few hours of exposure to the experimental salinities, with half of the final equilibrated concentration values attained by twelve hours. Animal weight was found to bear no significant relationship to the ionic regulatory activity observed. Renal involvement in regulation has been shown for all the ions, with the production of a urine hypertonic to the blood for chloride and magnesium, and a urine hypotonic to the blood for sodium, potassium, and calcium. Renal regulation was greater in winter animals for chloride, and greater in summer animals for sodium and potassium. Ionic regulation by the gills of summer and winter animals was investigated by potential difference measurements, and was suggested to occur for all ions. Chloride may have been regulated by the absorption from dilute media and excretion into concentrated media. Sodium may have been regulated by secretion into dilute media. The involvement of the gill in potassium, calcium, and magnesium regulation was implicated.
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