Efecto de la temperatura sobre la diferenciación sexual en juveniles de la langosta de agua dulce, Cherax quadricarinatus (Astacida, Parastacidae)

VAZQUEZ, F.; CHAULET, A.; BUGNOT, A. Y L.S. LÓPEZ GRECO

CONGRESO VIRTUAL DE ACUICULTURA 2004

REVISTA ACUATIC

Lugar: ZARAGOZA; Año: 2004 p. 255 - 259

The aim of this work was to determine the effect of temperature on sexual differentiation in the early juveniles of the freshwater crayfish, Cherax quadricarinatus (“red claw” crayfish).  Recently independent juveniles (stage III) obtained from two ovigerous females, were isolated in plastic containers filled with 200 ml of dechlorinated freshwater, fed daily ad libitum on Elodea sp and Tetradiskus® granules and mantained with a photoperiod of 14: 10 light: darkness. The juveniles were exposed to either 25-27ºC (n= 56) or 30-32ºC (n=56) temperature ranges. Molted or dead individuals were daily recorded. Twice a month, juveniles were weighed and observed under stereoscopic microscope to determine the presence of the genital openings at the basis of the third (females), fifth (males) or both (intersex) pair of walking legs. When all juveniles could be sexed, the proportion of males was compared by means of the exact test of Fisher. The exposure to 30-32ºC induced a greater proportion (p<0.05) of males (calculated on survival juveniles) compared to the group maintained at 25-27 ºC. Since in C. quadricarinatus, both males and females have a greater somatic growth in a monosex culture than in a mixed culture, also having isolated males a significant higher growth than females, the exposure of early juveniles to high temperatures could be an useful tool to improve the monosex male production in this species.