DEVELOPMENT OF A STATIC-WATER ECOASSAY WITH MICROCOSM TANKS FOR POSTLARVAL PENAEUS-VANNAMEI

A static-water ecoassay was developed to quantify the chemical impact of unassimilated nutrients and metabolic wastes on water quality in aq uaculture, Using shrimp as the test animal, increased stocking densiti es and feeding rates increased nutrient loading in the water column. A stocking density and feeding rate that resulted in high weight gain ( 28%/day) and survival (89%) of Penaeus vannamei postlarvae (PL) were s elected as appropriate for evaluating feed formulations. At the end of the 21-day growth trial, mass-balance analysis accounted, on average, for 90% of the phosphorus and 85% of the nitrogen that had entered th e culture system. Assimilation of phosphorus and nitrogen into shrimp biomass averaged 25% for phosphorus and 63% for nitrogen. This static- water ecoassay has good potential for laboratory evaluation of nutrien t dynamics in shrimp culture using 5- to 10-day-old PL at a stocking d ensity of 1.5 PL/1 (444 PL/m(2)) and a high variable feeding rate. (C) 1998 Elsevier Science B.V.