Recovery from hypoxia with and without sulfide in Saduria entomon: Oxygen debt, reduced sulfur and anaerobic metabolites

Abstract

The Baltic brackish water isopod Saduria entomon was exposed (8 h; T: 11°C; S: 10 ppt) to hypoxia (0.1 kPa) and to hypoxia (0.7 kPa) with sulfide (41 υM). Oxygen consumption was measured using computer-controlled intermittent respirometry. The routine oxygen consumption was 0.109 mg O2 h-1 g-1 at normoxia (19.5 kPa). The recovery from hypoxia with and without sulfide was studied in terms of oxygen debt, reduced sulfure concentration and anaerobic metabolites. In hypoxia, the metabolisms of S. entomon was reduced by 70% compared to the normoxic level and the oxygen debt was 0.57 and O2 g-1. Normal respiration rate was re-establish after 8 h of recovery. Lactate oxidation accounted for only 20% of the oxygen debt. Sulfide and detoxification products accounted for as little as 0.04% (υg O2 g-1 wet wt) of the oxygen debt. The majority (80%) of processes that occurred during the recovery from sulfide exposure are inferred to be involved in restoring normal cell function. Removal of internal sulfide and reoxidation of anaerobic metabolites play secondary roles.