Culture density effects on the age of reproduction and cysts production of fairy Shrimp Streptocephalus mackini

Abstract

DURING THE TRIAL NAUPLII OF FAIRY SHRIMP (STREPTOCEPHALUS MACKINI) WERE CULTIVATED IN THREE FRESH-WATER FISH BOWLS WITH 200 L OF FRESH-WATER, AT A DENSITY OF 100 ORG.L⁻¹, 25% DAILY WATER CHANGES, AND SEMI-CONTROLLED CONDITIONS OF TEMPERATURE (27 ± 3 °C), PH 7-8.5, PHOTOPERIOD (12 L: 12 O), DISSOLVED OXYGEN AT SATURATION, AND FEEDING WITH A DIET BASED OF MICROALGAE CHORELLA SP (1 × 10⁶CEL. ML⁻¹), TO EVALUATE THE VELOCITY OF GROWTH AND DETERMINE ITS EQUATION. SUBSEQUENTLY, THE EFFECT OF THE DENSITY OF CULTURE ON REPRODUCTIVE AGE (1:1 MALE: FEMALE) AND PRODUCTION OF CYSTS OF PRE-ADULTS OF THE SHRIMP WERE EVALUATED DURING 21 DAYS. FOUR TREATMENTS WITH THREE REPLICATES WERE TESTED: T1-50 ORG. L⁻¹, T2-100 ORG. L⁻¹, T3-150 ORG. L⁻¹ AND T4-200 ORG. L⁻¹; IN 12 CONTAINERS OF 3 L OF CAPACITY AND SEMI-CONTROLLED ENVIRONMENTAL CONDITIONS. THE ORGANISMS INITIATED THEIR REPRODUCTIVE PHASE, IN AVERAGE, AT 10 DAYS AFTER THEIR BIRTH, AND CONTINUED TO THE END OF THE TRIAL. IT WAS FOUND THAT THE MAXIMUM THEORETICAL LENGTH UNDER PREVAILING CONDITIONS WAS 26.49 MM, THE VALUE OF THE CONSTANT OF CATABOLISM WAS 0.034 MM AND SIZE AT THE TIME OF BIRTH WAS 0.896 MM. RESULTS INDICATE THAT DENSITY DIRECTLY AFFECTED THE PRODUCTION OF CYSTS AND SURVIVAL. THE FEMALES THAT REMAINED IN T1 PRODUCED SIGNIFICANTLY HIGHER NUMBER OF CYSTS (178.01 CYSTS/FEMALE) IN RELATION TO THE REMAINING TREATMENTS (Α = 0.05). THE SURVIVAL OF THE ORGANISMS IN T1 AND T2 (74.76 AND 71.33%) INDICATE THAT THE MASSIVE PRODUCTION OF THIS SPECIES CAN BE ECONOMICALLY FEASIBLE, UNDER THE CONDITIONS THAT WERE TESTED.