Increasing Production of Copepod Nauplii in a Brown-Water Zooplankton Culture with Supplemental Feeding and Increased Harvest Levels

Abstract Two experiments were performed to investigate increasing the number of copepod nauplii obtained from a brown-water zooplankton culture for feeding to larval red snapper Lutjanus campechanus. Brown-water zooplankton cultures rely on the regular exchange of (brown) estuarine water to nourish and harvest the copepods. The majority of copepods in both experiments were Acartia tonsa. The goal of the first experiment was to determine whether adding rice bran to a brown-water zooplankton culture would increase copepod density. Brown-water zooplankton cultures supplemented with rice bran had significantly higher naupliar densities than either brown-water zooplankton cultures without rice bran or zooplankton cultures supplemented with rice bran but without brown-water exchanges. Both the rice-bran-supplemented brown-water zooplankton culture and the rice bran zooplankton culture had higher copepodid densities than the brown-water zooplankton culture, but they were not different from each other. The goal of the second experiment was to determine the harvest rate (25, 50, and 75% of the water volume every other day) that would produce the most copepods. Copepod densities increased with a decrease in harvest rate; however, naupliar yields increased with increasing harvest rate. Copepod populations subjected to the various harvest rates appeared to undergo similar dynamics and were thus equally sustainable. There were significantly more nauplii harvested with the 75% harvest rate than with the other rates, but there was no difference in the number of harvested copepodids resulting from the different harvest rates. Naupliar yields of brown-water zooplankton cultures may be increased by rice bran supplementation and harvesting 75% of the culture volume every other day.