| dc.description.abstract |
The present study was done to establish the lethal salinity (LC50) and the effects of an abrupt change in the salinity on the oxygen consumption and the growth of postlarvae (PL10-PL21) of Litopenaeus setiferus, and their integration as assimilated energy. Postlarvae of L, setiferus presented a mean LC50 at 8 parts per thousand, and a time of response of 2 h. Thereafter, LC50 remained constant for the next 96 h. The effect of salinity on oxygen consumption and growth rate changed with the age of postlarvae. From PL10 to PL15, the highest oxygen consumption was obtained at 10 parts per thousand and the lowest ar:40 parts per thousand. During this time, growth rate increased with salinity with the maximum value in 40 parts per thousand and lowest at 10 parts per thousand. From PL15 to PL21, the highest oxygen consumption was obtained at 30 and 40 parts per thousand. In 30 and 40 parts per thousand, the growth rate was lower than that observed in animals maintained in 10 parts per thousand. The assimilation-salinity relationship changed with the age of the organisms. From PLIO to PL15, assimilated energy increased with a decrease in the salinity, and from PL15 to PL21, assimilation increased directly with an increase in the salinity. The inverse relationship between oxygen consumption and growth has been observed in other estuarine organisms and suggests that, when animals are found in an osmotically favorable medium, the processes of capture and distribution of the ingested energy are more efficient. These mechanisms change with age. From PL15 to PL21, an increase in the salinity produced an increase in the assimilation This was a result of an increase in the respiratory efficiency and, as a consequence, a reduction of the net growth efficiency. |
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