BIOENERGETICS OF PRAWN Macrobrachium tenellum (SMITH, 1871) DEPENDING ON WATER SALINITY

Background. The Macrobrachium tenellum prawn is captured and commercialized by local fishermen along its distribution interval.  It is considered an euryhaline palemonid prawn.  If its cultivation is wanted, the best conditions for its growth and reproduction should be investigated, including proper intervals of temperature, salinity, density and dissolved oxygen. Objective. To determine the effect of two different salinities (0 and 15PSU) on the physiological rates that balance the energy equation in M. tenellum adults and to determine if energy use is more efficient under isosmotic conditions. Methodology. Specimens were collected in Guasave, Sinaloa, Mexico, in July 2018 and taken to the Aquaculture Laboratory at UAdeO.  The energy balance was calculated in hyposmotic (0 PSU) and isosmotic (15 PSU) conditions at preferred temperature (28.5 ± 1 ° C). The energy invested in respiration and excretion, the feces lost and the ingested food and the growth potential was calculated using a semi-open respirometer. Results. The highest energy expenditure occurred in the respiratory rate (routine metabolism), then feces production and finally ammonia production in both salinities. The highest total energy expenditure was observed in fresh water. The highest amount of energy directed to the growth or reproduction was observed in brackish water (15 PSU), as well as the highest rate of food ingestion. Implications. Knowledge on the use of energy in the feed in the best saline condition for its cultivation useful for culture purposes. Conclusion. The saline condition in where more energy is channeled for the growth of M. tenellum is 15UPS (isosmotic point) and in it is also in where less energy is spent.