Acclimation of adult males of Litopenaeus setiferus exposed at 27 degrees C and 31 degrees C: Bioenergetic balance

Abstract

The reduction of reproductive performance of adult males of Litopenaeus setiferus in captivity has been limiting the massive nauplii production, mainly by lowering the spermatophore attachment success associated with the male reproductive tract degenerative and the male reproductive melanization syndromes. Both syndromes had been related to the captivity and management stress. In this study the bioenergetic alterations were measured after seven days in captivity through absorption efficiency (AE), absorption (A), routine respiratory rate (R-ROUT), apparent heat increment (R-AH1), ammonia excretion (U) and post-prandial nitrogen excretion (PPNE), as indexes of captivity stress in adult males of L. setiferus kept at 27 and 31 degreesC. All this parameters were integrated through the production equation (P-t) =A - (R-AH1 + R-ROUT + U) At 31 degreesC the equation values were higher than those observed at 27 degreesC, except for R-ROUT and ammonia excretion. The amount of energy directed to P-T at 31 degreesC was 1784.99 j g(-1) afdwd(-1), in contrast with shrimp exposed at 27 degreesC, where it was 1269.22 J g(-1) afdw d(-1) (P > 0.05). The O:N ratio obtained was lower than 10, indicating the use of a proteic substrate (P > 0.05). The reduction of the metabolic responses at high temperature shows what the adaptation capability of this shrimp is to tolerate a wide range of temperatures, also reflecting the adaptation mechanisms associated with its distribution in shallow coastal waters.