QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by SUTCLIFFE, D. W. Articles by SHAW, J. Search for Related Content PubMed Articles by SUTCLIFFE, D. W. Articles by SHAW, J.

Journal of Experimental Biology 48,339-358 (1968)
Published by Company of Biologists 1968

Sodium Regulation in the Amphipod Gammarus Duebeni Lilljeborg form Freshwater Localities in Ireland

D. W. SUTCLIFFE ¹ and J. SHAW ²

¹ Department of Zoology, University of Newcastle upon Tyne; Freshwater Biological Association, The Ferry House, Far Sawrey Ambleside, Westmorland
² Department of Zoology, University of Newcastle upon Tyne

1. A quantitative study of sodium influx and loss was made on populations of Gammarus duebeni obtained from four freshwater localities in Ireland.

2. Characteristic features of sodium regulation in animals from the four localities were as follows, (a) The sodium influx increases gradually with increasing external sodium concentrations, but a maximum (saturation) level is abruptly reached at an external concentration of 1-2 mM/l. and the transporting system is half saturated at about 0.5 mM/l. sodium, (b) Over the range of sodium concentrations found in fresh waters a low rate of sodium uptake is sufficient to balance sodium losses at concentrations down to between 0.5 and 0.25 mM/l. At lower concentrations the influx is increased and the loss rate is reduced. (c) Calculations suggest that hypotonic urine containing approximately 40 mM/l sodium is produced at external concentrations ranging from fresh water to 40 % sea water. At external concentrations below 0.25 mM/l. sodium the urine concentration is probably reduced to well below 40 mM/l. sodium.

3. A detailed comparison is made of sodium regulation at external concentrations ranging between 0.07 and 1 mM/l. sodium in G. duebeni from fresh water in Ireland and from fresh water and brackish water in Britain. It is suggested that G. duebeni in Ireland constitutes a distinct physiological race adapted for living in fresh waters with relatively low sodium concentrations.