The pond's shape matters: differential growth, physiological condition and survival of epibenthic Farfantepenaeus aztecus postlarvae.

As a function of the water quality provided by square, circular and oval experimental ponds, the growth, survival and oxygen requirements in epibenthic postlarvae of Farfantepenaeus aztecus were analysed in relation to their routine metabolism and apparent heat increment. Temperature, oxygen concentration, pH and salinity were measured daily in two experimental ponds of each shape. The postlarvae oxygen consumption during two 24-h cycles, their growth, physiological condition and survival and the productivity in the ponds were estimated. Low values of pH, oxygen concentration and phytobenthos productivity, and reduced postlarvae relative growth and survival were observed in the square ponds. We suggest that the latter results from a deficient water circulation related to the effect of the pond's shape on dissolved oxygen levels and, consequently, on growth and survival. The postlarvae routine metabolism, including feeding, varied between 1.91 and 2.25 mg O₂ h⁻¹ g⁻¹ wet weight, whereas the minimum oxygen concentration needed in the ponds is approximately 4.25 mg O₂ L⁻¹. These conditions were achieved in the oval ponds concurrent with higher survival and growth values, in which individuals distributed randomly, for which we suggest that oval-shaped ponds could be the most adequate for the culture of this and other penaeid species. [ABSTRACT FROM AUTHOR]