Theses and Dissertations


Title: Collection and Acclimation of Copepod Nauplii for Feeding Larval Red Snapper Lutjanus Campechanus

Name: Lan, Hsiang-Pin

Degree: MS

Chair: Ronald P. Phelps

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2001

Pages: 73

Keywords: first feed,red snapper,copepod,acclimation

Abstract:

A series of experiments were conducted to develop a protocol for collecting copepod nauplii from fertilized brackish water ponds, acclimating nauplii from low salinity to high salinity, and evaluating the effect of food density on red snapper (Lutjanus campechanus) larvae. In the first study, two trap designs were developed and evaluated for the collection of copepod nauplii from fertilized ponds. Trap I was designed to collect copepods over an extended period of time at a slow pumping rate. Trap II was designed to collect mass quantities of copepod nauplii with less clogging problems. Trapping regimes were conducted during the day, night without a light and night with a light in Trap I trial. Trap II trial was conducted during the day over a short (4 to 4.5 h) or long (8 to 9 h) period and over a long (9 to 10 h) period at night. Trapping efficiencies and the number of copepod nauplii collected/h were similar among trapping regimes in each design's trial. The mean number of copepod nauplii collected was 36,204/h using Trap I and 690,006/h using Trap II. In the second study, copepod nauplii were acclimated to seawater over three time periods to determine the appropriate acclimation time. Copepod nauplii were acclimated in 6-h, 12-h, or 24-h periods from the original pond salinity of 8 ppt to 32 ppt seawater. Mortalities were observed at just before acclimation, just after acclimation, 6, 12, 24, and 48 h after acclimation. Mean mortalities were similar among the three different acclimation periods. The 6-h acclimation did not result in higher mortality than that of nauplii acclimating in a longer period. Copepod nauplii mortality increased in both the treatment and control containers according to the time of post harvest. In study three, red snapper larvae were fed copepod nauplii as the first food at a target density of 1, 10, and 20/mL from day 2 to 16 post hatch and artemia at a density of 2/mL from day 15 to 30 post hatch. Copepod nauplii and artemia densities were counted daily and additions made to bring the concentration back to the target density. Fish larvae were harvested at day 32 post hatch. The survival rate and mean body length was relatively similar among treatments ranging from 0.1% to 1.4% and 1.64 cm to 2.59 cm, respectively. Survival was not correlated to body length. Copepod nauplii depletion rate was not correlated to larval survival or growth.

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