The effect of ambient pH on electrolyte regulation during the postmoult period in freshwater crayfish Procambarus clarkii

• Published in: Journal of experimental biology Vol. 178; no. 1; pp. 1 - 19
• Main Authors: ZANOTTO, F. P, WHEATLY, M. G
• Format: Journal Article
• Language: English
• Published: Cambridge Company of Biologists 01-05-1993; The Company of Biologists Ltd
• Subjects: Biochemistry; Biochemistry. Physiology. Immunology; Biological and medical sciences; Calcium; Crustacea; Fundamental and applied biological sciences. Psychology; Invertebrates; Physiology. Development; Shellfish; Calcium; Hemolymph; Environmental factor; Molt; Macrura; Crustacea; Freshwater environment; Regulation(control); Arthropoda; pH; Decapoda; Procambarus clarkii; Invertebrata
• ISSN: 0022-0949; 1477-9145
• DOI: 10.1242/jeb.178.1.1

The effects of ambient pH on postmoult net fluxes of Ca, acidic/basic equivalents (H+, NH4+/OH−, HCO3−), Na and Cl−, total body Ca, haemolymph pH and electrolyte status were assessed in the freshwater crayfish Procambarus clarkii (Girard). Variables were monitored for 5 days postmoult in acidic (pH5.2; H2SO4) or alkaline (pH9.2; KOH) artificial tap water (ATW) and compared with those in control (pH7.4) tap water. In control ATW there was an initial net influx of Ca (+2700 μmolkg−1 h−1) and titratable basic equivalents (+5000 μmolkg−1 h−1) that declined with time. Calcium uptake accounted for 40% of total body Ca (0.49mmol g−1); haemolymph Ca concentration remained constant. Haemolymph pH was initially relatively alkalotic (7.7) but recovered within 24h. A 20% haemolymph dilution by water uptake at ecdysis necessitated uptake of Cl− and Na for the first 2–3 days postmoult (+1000 μmolkg−1 h−). In acidic ATW, Ca and basic equivalent uptake were both 60% reduced during the first 3–4 days and total body Ca was reduced by 37%. Chloride and Na uptake and haemolymph [Cl−] were decreased. In alkaline ATW, Ca and basic equivalent uptake were elevated by 30% for the first 2 days and haemolymph alkalosis was maintained. Sodium and Cl−balance were unaffected. Thus, ambient pH affects Ca and basic equivalent fluxes associated with postmoult calcification. Regulation of Na and Cl−levels is also impaired in acidic ATW.