3.4. Study 3 water quality and BOD
Mean TAN and chlorophyll a concentrations in ponds did not differ
significantly by sample date, but salinity increased significantly over
time (Table 6). Mean coefficient of variation for measured DO
concentrations for replicate samples at each time period was low
and averaged 2.6%. A representative DO consumption curve for
replicate pond and canal samples is shown in Fig. 2. The mean BOD
:
BOD
88–94
ratio was 0.35. The BOD
for the harvest sample was
significantly lower than for the 30- and 61-d samples, which did not
differ. Pond BOD
88–94
5
for the harvest and 61-d samples was
significantly lower than for the 30-d sample. Computed UBOD,
however, did not differ significantly among sample dates, and
averaged 61.30 mg L
−1
. The mean decomposition rate constant was
0.071 d
−1
. The computed UBOD and BOD
in pond water were
linearly related (R
2
(d) (kg ha
5
−1
d
−1
) (kg ha
=0.899). The increment in BOD that resulted from
shrimp culture was calculated using the water supply canal BOD
because no estuarine BOD data was available. The water supply canalBOD at day 61, which was higher than for the pond likely because of
the high phytoplankton biomass, was not used in calculating
incremental BOD. After 30 d of culture, incremental BOD
was
57.8 mg L
−1
was 39.7 mg L
, but at harvest (70–72 d of culture) incremental BOD
−1
.
88
94
3.4. Study 3 water quality and BODMean TAN and chlorophyll a concentrations in ponds did not differsignificantly by sample date, but salinity increased significantly overtime (Table 6). Mean coefficient of variation for measured DOconcentrations for replicate samples at each time period was lowand averaged 2.6%. A representative DO consumption curve forreplicate pond and canal samples is shown in Fig. 2. The mean BOD:BOD88–94ratio was 0.35. The BODfor the harvest sample wassignificantly lower than for the 30- and 61-d samples, which did notdiffer. Pond BOD88–945for the harvest and 61-d samples wassignificantly lower than for the 30-d sample. Computed UBOD,however, did not differ significantly among sample dates, andaveraged 61.30 mg L−1. The mean decomposition rate constant was0.071 d−1. The computed UBOD and BODin pond water werelinearly related (R2(d) (kg ha5−1d−1) (kg ha=0.899). The increment in BOD that resulted fromshrimp culture was calculated using the water supply canal BODbecause no estuarine BOD data was available. The water supply canalBOD at day 61, which was higher than for the pond likely because ofthe high phytoplankton biomass, was not used in calculatingincremental BOD. After 30 d of culture, incremental BODwas57.8 mg L−1was 39.7 mg L, but at harvest (70–72 d of culture) incremental BOD−1.8894
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