Date of this Version
Great Salt Lake-biotype brine shrimp cysts were added to 440-1 saltwater cultures maintained at 20° ,25° , and 30° C. A micronized corn-byproduct was added each day as food. Planktonic bacteria found during growth of the brine shrimp were enumerated on Plate Count Agar (Difco). From the 25° and 30° brine shrimp cultures, a total of seven prevalent bacterial types (five gram-negative and two gram-positive) were isolated from throughout the 12-day growth cycle. Eight antimicrobial agents were tested against these bacteria, with chloramphenicol the most effective antibacterial agent overall, followed by erythromycin and carbenicillin. The bacterial density of the culture medium upon cyst addition was 106 colony forming units (cfu)/ml. The density increased similarly in all cultures from day 1 to day 3, and continued to increase in both the 25°- and 30°- cultures to between 108 and 109 cfu/ml at the end of day 12, at which time many brine shrimp had reached sexual maturity. However, the bacterial density in the 20°- culture dropped after day 8, the culture medium became less turbid and the brine shrimp did not reach sexual maturity by day 11. Brine shrimp densities from 8 g of cysts were 2.5 animals/ml (day 11) at 20° , 3.0 animals/ml (day 11) at 25° , and 2.7 animals/ml (day 12) at 30°. Final wet weights from one data set were 5.1 g/l at 20° , 10.2 g/l at 25° , and 8.5 g/l at 30° for 12-day-old brine shrimp. The high initial and 1,000-fold increase in density of planktonic bacteria in both the 25°- and 30°- cultures was concomitant with significant accrual of Artemia franciscana biomass.