DIFFERENTIATION OF THE MALE REPRODUCTIVE SYSTEM IN THE FRESHWATER CRAYFISH Cherax quadricarinatus

FERNANDA J. VAZQUEZ; LAURA S. LÓPEZ GRECO*

VERACRUZ, MEXICO

Congreso; WAS AQUACULTURE 2009; 2009

World AQUACULTURE SOCIETY

Differentiation of the male reproductive system in the freshwater crayfish Cherax quadricarinatus Fernanda J. Vazquez; Laura S. López Greco* Dept. of Biodiversity and Experimental Biology, FCEyN, University of Buenos Aires Ciudad Univ. C1428EHA, Buenos Aires, Argentina. laura@bg.fcen.uba.ar Cherax quadricarinatus is a crayfish species of growing importance in freshwater aquaculture but many aspect of their reproductive biology are still unknown. The aim of this study was to characterize the sexual differentiation and onset of maturity in males. For this purpose, males of C. quadricarinatus (0.09 to 150 g) were weighted, the carapace length (CL) was measured and the gonads and vasa deferentia were inspected and processed for histological analysis. The presence of the appendices masculine, (lobular or elongated) and the “red patch” were also recorded. Three developmental stages were recognised: B A B A Stage I: The differentiation of the reproductive system begins (Table 1). The testes are differentiated into two parallel cords and they tend to acquire an X-shape with a few small lateral lobules (Fig 1A). No spermatophore is evident within the vas deferens. At this stage, males develop lobular appendices masculinae that present a rounded, transparent and not very cuticularized aspect (Fig. 1B). E D C C D Stage II: The testes present a greater size and higher number of lobes with respect to the previous stage (Fig. 1C and Table 1). The testes are differentiated as an H. Males begin to elongate their appendices masculinae. Figure 1: Histological and morphological characterization of the three developmental stages of C. quadricarinatus males. F Stage III: As the animal size increases, the relative size of the reproductive system and the number of testicular lobes, increase as well (Fig D). All males present elongated appendices masculinae and “red patch” (Table1; Fig 1E,F) Table 1: Macroscopic and microscopic characterization of the three stages. (+) Presence (-) Absence. The quantitative differences for a given character are indicated by increasing the number of (+). The present study shows that differentiation of sexual characters occurs simultaneously and very early. This could be useful for the culture of the species, since it demonstrates that males begin to derivate energy towards spermatic production and spermatophore formation from earlier sizes than the previously reported.  According to the present study, males should be separated from females earlier in development in order to avoid shifting of energy towards reproduction maximizing the energy from nutrients towards somatic growth. Financial support: UBACYT X458; PIP 112-200801-00129 and PICT 2007 area: PESCA 01187. We thank Lic. Carlos Anselmi, Las Golondrinas Farm, Argentina, for supplying the crayfishes.