EFFECT OF TEMPERATURE ON MOLT INCREMENT AND INTERMOLT PERIOD OF A JUVENILE AUSTRALIAN FRESH-WATER CRAYFISH, CHERAX DESTRUCTOR

The effect of 3 temperatures (22, 25, and 28 degrees C) on molt increm ent and intermolt period in juvenile C. destructor (the yabby) was inv estigated under laboratory conditions. Newly independent juveniles wer e grown individually in 1-1 polyethylene containers for 6 molts from m olt stages 3-9. Both the intermolt period and molt increment decreased with increasing temperature. The mean intermolt periods were 6.7, 5.5 , and 5.0 days and mean molt increments were 102, 98, and 93% at 22, 2 5, and 28 degrees C, respectively. Regression models derived by combin ing molt increment and intermolt period data indicated that overall gr owth increased with increasing temperature. Pairwise comparisons of re gression coefficients indicated that the growth rate of juvenile C. de structor at the two higher temperatures (25 and 28 degrees C) did not differ, but was significantly reduced at 22 degrees C. Thus, a shorter intermolt period, in spite of a reduced molt increment, is responsibl e for superior growth of juveniles of this species at elevated tempera tures.