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International Journal of Aquaculture 2012, Vol.2, No.6, 29-39
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32
Figure 2 Characterization of fluorescent dependent water
particulate
Note: Characterization of algal/plankton populations 1~6 as
determined by both red and green auto-fluorescence. Lines have
been fitted to the points using a Loess regression. The shaded
area represents a 95% confidences interval for the regression line.
Points are individual measurements from each tank
Figure 3 Fluctuation of size dependent biofloc determined with
flow cytometry
Note: Plankton populations observed in raceways utilizing settling
tanks (ST) or foam fractionation (FF). Using flow cytometry,
cells were characterized according to three sizes: solid
line=picoplankton (0.2 to 1.0 µm), dotted line=nanoplankton (5 to
10 µm) and dashed line=plankton greater than 10 µm. Lines have
been fitted to the points using a Loess regression. The shaded area
represents a 95% confidences interval for the regression line.
Points are individual measurements from each tank
according to the adjusted R-squared value. The
variability in gram-positive bacteria was negatively
influenced by NO
2
-N (
p
<0.01) and positively by
NO
3
-N (
p
<0.05). Turbidity and cBOD
5
displayed
insignificant negative influence on gram-positive
bacteria variability. The variability in macro, nano,
and pico particles as well as the variability in
autofluorescent regions could not be well described
using multiple linear regression models of water
quality parameters (
p
>0.05). The variability of
gram-positive.parameters compared to that of foam
fractionation. In particular VSS (
p
<0.05) and cBOD
5
(
p
<0.01) accounted for a majority of the influence.
The full model (
p
<0.01) describing 95% of the
variability also included PO
4
+
, TSS, and turbidity.
Similarly to foam fractionation, size based particulates
as well as autofluorescent regions could not be well
described by multiple linear regression models
(
p
<0.05).
Statistical analysis of shrimp harvest data indicate no
We have shown in support of previous research exist
in mean final weight between treatments. However,
we observed growth rates varying between 1.35 g/wk and
1.39 g/wk whilst final shrimp weights were 21.9 g and
22.4 g. It is also noteworthy to report that survival
rates were high in all four raceways (94.5%~96.8%);
FCR was between 1.53 and 1.60. Shrimp yields were
9.34 kg/m to 9.75 kg/m, although the latter weight
represented one sample in the FF raceway. The
volume of water per 1 kg of shrimp produced used in
the raceways varied between 98 L to 126 L.
2 Discussion
We have shown in support of previous research
(Menasveta, 2002; Wasielesky Jr. et al., 2006; Ballester
et al., 2010), the efficacy of super-intensive zero
exchange systems to produce market-sized
L. vannamei
at a very high culture density (450 shrimp/m
3
)
without the indication of disease. This technique is
considered efficient, sustainable, biologically secure,
environmentally sound, and therefore an alternative to
traditional aquaculture methods, which have notable
environmental impacts (Páez-Osuna, 2001a; 2001b).
Unlike other super-intensive zero exchange shrimp
rearing studies, we utilized water from a successful
62-day
L. vannamei
growth period from larvae to
juvenile. We define successful as disease free with
low incidence of mortality (<5%). We consider this