The effects of stress caused by low temperature, high salinities, and a combination of both low temperatures
and high salinities were evaluated in advanced (~5 g) juvenile freshwater crayfish (Cherax quadricarinatus).
Ten animals were weighed and assigned to each of the following combination of two temperature and three
salinity treatments: 27 °C (optimum for this species) or 20 °C and 0, 5, and 10 g/L salt concentrations. After
30 days in each treatment, oxygen consumption and weight were recorded, together with hemolymph levels
of glucose, sodium, potassium, and free amino acids (FAA). Glycogen level was determined in hepatopancreas
and abdominal muscle, while FAA levels were measured in abdominal muscle and hemolymph. A significant
decrease of weight gain was seen at the combination of 20 °C and 10 g/L salinity. A marked hyperglycemia
was seen at the lower temperature, at any salinity tested. At the same temperature, there was a concomitant
decrease of glycogen, in both hepatopancreas and muscle. Both sodium and potassium hemolymphatic levels
significantly increased with increasing salinity, but only at 20 °C. No changes were seen in hemolymphatic
FAA levels, but they increased in abdominal muscle at higher salinities, in correspondence with the sodium
hemolymphatic increase, in order to regulate cellular osmolarity. Although advanced juveniles of C. quadricarinatus
did not exhibit reduced survival or growth at 20 °C or 10 g/L salinity, the combination of relatively
low temperature and high salinity significantly reduces growth, suggesting that the combination of these two
factors is a stressful condition for these crayfish juveniles.