Haemolymph nitrogen compounds and ammonia efflux rates under anoxia in the brackish water isopod Saduria entomon

• Published in: Marine ecology. Progress series (Halstenbek) 1994-01, Vol.103 (3), p.285-289
• Main Authors: Hagerman, Lars, Szaniawska, Anna
• Format: Article
• Language: English
• Subjects: Amino acids; Ammonia; Anaerobiosis; Anoxia; Blood; Brackish; Brackish water; Crustaceans; Excretion; Hemolymph; Hypoxia; Marine; Saduria entomon
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps103285

Production and excretion of nitrogenous end products was studied in the benthic Baltic isopod Saduria entomon (L.) under normoxic and anoxic conditions. S. entomon is ammonotelic. Normoxic haemolymph ammonia concentrations were 176 ± 53 (SD) μmol NH4+ l−1 decreasing with time to 50 μmol NH4+ l−1 after 120 h anoxia. Normoxic ammonia efflux rate was 0.53 ± 0.07 (SD) μmol NH4+ g−1 h−1, decreasing 90% after 96 h anoxia. Normoxic haemolymph urate amounted to 135 μmol l−1, increasing after 120 h under anoxia to 741 ± 79 (SD) μmol l−1. Haemolymph urate concentrations were relatively high because of the ammonia excretion and an undetectable urate excretion even under anoxia. Circulating free amino acids also increased progressively under anoxia, from the normoxic 28 to 165 mmol l−1 after 96 h anoxia. This increase was largely due to accumulation of alanine as a result of an anaerobic metabolism. Ammonia was calculated to be the quantitatively dominating nitrogenous end product in S. entomon. An effective efflux of ammonia prevents an excessive build-up of toxic ammonia in the haemolymph.