World Aquaculture December 2018

46 DECEMBER 2018 • WORLD AQUACULTURE • WWW.WA S.ORG in Texas (Sager et al. 2007). Its effect on crustaceans is not well investigated but high concentrations have been anecdotally correlated with shrimp mortality in past years, although there was no apparent shrimp mortality associated with the presence of Prymnesium in this study. The density of Oscillatoria increased toward the end of the production trial at GPA (mean range: 207-222 million cells/L) which was much higher than detected at FS (mean range: 8-28 million cells/L). Their occurrence was likely associated with higher water temperature and increased pond fertility resulting from feed inputs. High concentrations of Oscillatoria have been associated with shrimp mortality in the past on this farm but there was no apparent correlation in this study as probiotic-treated and control ponds had similar levels of Oscillatoria . In summary, no significant differences in the density of golden or blue-green algae were observed between probiotic-treated and control ponds on either Alabama farm despite manufacturer claims that the probiotic will reduce the occurrence of blue-green algae. Shrimp Disease and Histopathology Effects Shrimp were tested for the presence of OIE-listed diseases at stocking and at harvest. No listed viruses, NHP or AHPND were detected. The probiotic, when tested in the laboratory at the U.S. Department of Agriculture Agriculture Research Service Aquatic Animal Health Laboratory in Auburn, AL using in vitro techniques revealed moderate efficacy at preventing the growth of Vibrio parahaemolyticus and V. alginolyticus (Fig. 9). Both pathogenic (green colonies) and non-pathogenic (yellow colonies) species of FIGURE 10. Pond water Vibrio counts through time in control ponds and in ponds treated with probiotics on three different farms, including Gulf American Shrimp (a), Greene Prairie Aquafarm (b) and Forkland Springs (c). No significant differences were observed between control and treated ponds on any of the farms (p>0.05). FIGURE 11. Pond water Vibrio type in pond water of three different farms over time in ponds that had been treated with probiotics or not treated on three different farms including Gulf American Shrimp (a), Greene Prairie Aquafarm (b) and Forkland Springs (c). The green color represents pathogenic Vibrio and the yellow represents non-pathogenic Vibrio . a. b. c. a. b. c.