INFLUí­Å NCIA DA SALINIDADE NA ECLOSÃO DOS OVOS E NO DESENVOLVIMENTO LARVAL DE Macrobrachium rosenbergii DE MAN (DECAPODA, PALAEMONIDAE

Resumo

The determination of the ideal values of salinity for hatching and larval development of Macrobrachium rosenbergii is a very important factor in the hatcheries optimization process and the know of the physiology of that species. The hatched egg number in function of salinity was determined in ovigerous females maintained under 6 values of salinity: 0, 4, 8, 12, 16 and 20‰ S. The experiment development was based on a wholly casualized plan with different numbers of replications by treatment. Thus, the covariance analysis shows that the female total length (L_T) and the hatched egg number (L_OC) do not differ statistically from the adjusted number (L_AJ) expressed by equation L_AJ = L_OC- 3579.55 (L_T - 14.796). The larvae after hatching were transferred to 30 liters plastic containers with biological filter and in a 20 larvae/liter density, in a total of 600 larvae (1,800 in 3 replications). The larvae were maintained under 8, 10, 12, 14, 16, 18 and 20‰ S salinity values with the purpose to verify the salinity effect in larval development. This experiment was based on the wholly casualized plan with different numbers of replications by each treatment. It was verified that the number of the new metamorphosed post-larvae increased with salinity. The 18‰ S value provides the best results. The data permit to conclude that the hatching of Macrobrachium rosenbergii in laboratory was independent on salinity under what ovigerous females were maintained, while it is recommended 18‰ S salinity value to increase both survival in the larval cycle and the post-larvae production in a short time. This fact is justified by similar isosmotic balance point.