Ion regulation in two species of estuarine crabs

Abstract

In low salinities sodium, potassium and calcium ion concentrations in the blood of both species, Hernigrapsus nudus and H. oregonensis, are hypertonic to the media. In high salinities, ion regulation is less effective and concentrations approach isotonicity. This regulation is effected by extra-renal processes, since U/B ratios approximate unity. Blood concentration of magnesium is regulated in both species at a hypotonic level, one-third that of the medium concentration in all salinities. It is suggested that the principal site of ion uptake from the medium in Hernigrapsus is the lamelIar epithelium of the gill. Winter animals of both species appear to be more effective regulators of the calcium ion in low salinities. All other ion concentrations are similar, summer and winter. No consistent temperature effect could be demonstrated for ion concentration in blood or urine. The principal function of the antennary glands is to maintain a blood magnesium concentration hypotonic to all salinities. It is suggested that this regulation of magnesium is necessary to facilitate neuromuscular transmission and is a characteristic feature of ionregulation in active decapod crustacea. Ion regulatory ability of the two species differed only with respect to winter blood levels of sodium. H. oregonensis more effectively regulates this ion at hypotonic blood levels in high salinities. Chloride regulation in the two species demonstrates that the blood is hyperosmotic in low salinities and hyposmotic in higher salinities. Urine is hyperosmotic over the entire salinity range and is approximately 35 to 40 o/0 higher than the blood. Blood concentrations of chloride approximate a gradient of 15 to 30% above the experimental media. U/B ratios suggest that the antennary gland is not solely responsible for the regulation of this ion. Chloride regulation in the muscle of H. nudus demonstrates that in a high blood chloride environment, muscle chloride remains low, about one-third that of blood. Consideration of muscle cations of H. nudus shows that blood sodium is about

DOI: 10.1007/BF01610058

Cite this paper

@article{Dehnel2005IonRI, title={Ion regulation in two species of estuarine crabs}, author={Paul A. Dehnel}, journal={Helgol{\"a}nder wissenschaftliche Meeresuntersuchungen}, year={2005}, volume={9}, pages={474-475} }