The effect of salinity on oxygen consumption and osmoregulation ofMacrobrachium tenellum

A study was made of the effect of salinities of 0, 3, 6, 9, 12, 17, 22 and 27%o on the oxygen consumption and osmoregulation of Macrobrachium tenellum. The metabolism salinity curve is “U” shaped although in freshwater the metabolic rate reduces by 38%. The oxygen consumption observed over this range of salinities corresponds to Type II of Kinne (1971). In M. tenellum, osmotic concentration of haemolymph remains constant around 531 mmol Kg‐1 which means that this species is a strong hyper‐hypo osmoregulator. The isosmotic point was 533 mmol Kg‐1which suggests that this species has only recently invaded the freshwater environment.