The interactive effect of water-borne cadmium and environmental hypoxia on common carp (Cyprinus carpio) metabolism

Regarding to the tight association between aquatic hypoxia and heavy metal contaminations in one hand and the role of both parameters on fish respiration, metabolism of carp could be assessed under single and mutual exposures to hypoxia and cadmium. Following measuring LC50-96h of cadmium (43.679 mg/l) for this species, 80 common carp were exposed to 10 different treatments, including control, acute (43.68 mg/l), sub-lethal (21.84 mg/l) and chronic (4.37 mg/l) cadmium as well as hypoxia for immediately (20% of saturation), 24h (40%) and 7 days (60%), and joint exposure of each similar treatment. By using of respirometer technique, we measured oxygen consumption rate in different time spans to calculate each individual standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS), factorial aerobic scope (FAS) and critical oxygen tension (PCrit). Obtained data show that acute and sub-lethal cadmium treatments led to significant (P