TABLE OF CONTENTS Pages Symposium 1 - the National Sea ...

RESULTS AND DISCUSSION:
Nine different commercial or research recirculating aquaculture facilities were
sampled. Two were mariculture facilities, growing flounder. The six freshwater
facilities were all producing tilapia. There was one hydroponics research facility that was
circulating filtered fish wastewater through plant beds before being sent back to the fish
tanks.
The nine facilities tested used different materials. Almost all of them used
polyvinyl chloride (PVC) for water pipes. Many of the systems used fiberglass and/or
plastic tanks. Other substances used in the aquaculture systems tested were glass,
stainless steel, rubber, aluminum, foam and cement. An unbalanced random block
statistical model was used to test whether pathogen growth was influenced by the type of
material, the type of facility, and the history of disease, or whether all of them were
significant.
Materials
1 2 3 4
Facilities
5 6 7 8 9
1
Fiberglass/
Plastic
1 17 9 1 12 4 7 15 4
2 PVC 3 6 3 3 11 2 1 - 6
3 Other 1 - - 3 - 5 2 16 10
History of
Disease
N N N Y N N Y Y Y
Figure 1.
Figure 1 shows the data used to determine the statistical analysis. The SAS
System for Windows V7 program was used to determine the relationship between the
growth of pathogens and the type of material. The p value was well above the 5%
significance level, indicating the type of material was not a significant factor in
determining the presence of pathogenic bacteria. A similar response was obtained when
comparing the history of disease. Running a comparison of the least squares means and
doing Tukey’s test supports this. However, when comparing facilities the p-value =
0.0027. This indicates that at least one facility showed a significant difference in
pathogen growth.
SAS Institute, Inc., Cary, NC 27513