Effect of four temperatures on the survival and growth of freshwater prawns (Decapoda, Caridea): a comparison between species.

MONTAGNA, MARCELA CECILIA

IHERINGIA. SéRIE ZOOLOGIA

FUNDACAO ZOOBOTANICA RIO GRANDE SUL

Lugar: Porto Alegre - RS - Brasil; Año: 2010

0073-4721

During the two-month rearing period, the effect of four water temperatures (15º, 20º, 25º and 30ºC) on survival rate, number of molts, and growth rate (molt increment and intermolt period) of juvenile Macrobrachium borellii and Palaemonetes argentinus prawns was evaluated. The two species showed some similarities in their survival and growth pattern at different temperatures. First, the survival rate was the highest at 20º and 25ºC, and it decreased at the lowest temperature. Second, the number of molts increased with the temperature increment. Third, the intermolt period was shorter at higher temperature, ranging respectively from about 22.2 days at 15ºC to 9.9 days at 30ºC for M. borellii, and from 20.8 to 9.5 days at the same temperatures for P. argentinus. Thus, there were no differences between species in the intermolt periods at 15° and 30°C. Fourth, the percentage of molt increment increased significantly from 15° to 25°C, whereas a reduction in the growth of prawns was observed at 30ºC. Significant variations were found in the slopes of the relationships between the percentage of molt increment and cephalothorax length in the temperature treatments. The differences between the two species were that M. borellii showed a significantly higher tolerance to elevated temperature and a faster growth (about twice at 25ºC) than P. argentinus. These differences could provide to M. borellii a competitive advantage in the dynamic of freshwater environment and areas with anthropogenic impact.