Comparison Of Bacterial Quantitative Dynamics And Environmental Changes In Differing Shrimp Culture Models

Bacterial dynamics of heterotrophic bacteria, Vibrio, Bacillus, and fecal coliforms were studied in waters and sediment of desalting culture,intensive culture,and ecological culture ponds for shrimp from September 2007 to August 2008 in Guangdong. The aim of the study was to evaluate variations of the primary bacteria groups of different shrimp culture models to 1) provide the basic data and 2) derive theoretical bases for healthy shrimp culture.Heterotrophic bacteria, Vibrio's and Bacillus in the prophase of cultivation were unstable, becoming stable in the mid-anaphase of cultivation. Ranges were 1.8×l0³-1.2×l0⁵CFU·ml^-1, 1.4×l0²-4.0×l0³ CFU·ml^-1 and 1.6×l0²-1.7×l0³ CFU·ml^-1, respectively. In bottom sludge, heterotrophic bacteria remained constant while the Vibrio's initially increased then declined; Bacillus increased through time. Densities of three groups of bottom sludge bacteria were higher than in the overlying water by 2 - 3 orders of magnitude; ranges were 1.0×l0⁶-2.2×l0⁷CFU·g^-1,7.0×l0³ - 4.7×10⁵CFU·g^-1and 4.7×l0⁴ - 2.4×10⁶CFU·g^-1 respectively.In the intensive mode of the shrimp cultivation pond, change of heterotrophic bacteria, Vibrio's and Bacillus were greatly. Quantities of Bacillus and fecal coliforms were low. Vibrio, Bacillus and heterotrophic bacteria ranged from 1.05×l0³-5.20×l0⁴ CFU·ml^-1, 0.11×l0³-4.30×l0³ CFU·ml^-1 and 1.35×10⁴-1.39×10⁶CFU·ml^-1, respectively. Fecal coliforms were lower than 100·L^-1, with a mean density≤97cfu·L^-1. Heterotrophic bacteria and DO were positively correlated ( P<0.05 ); Vibrio's and pH were inversely related (P<0.01) while these bacteria were directly related to COD and TP (P<0.05).During breeding mode of the cultivation pond, heterotrophic bacteria in the water approximated 6.4×l0³ - 3.00×10⁵ CFU·mL^-1. Vibrio's were low, at 0.1×l0³-1.65×l0⁴CFU·mL^-1. Bacillus was also low, ranging from 0.06×l0³-1.09×10³CFU·mL^-1. The abundance of heterotrophic bacteria in the bottom sludge was relative high, ranging from 5.8×l0⁵-2.95×l0⁷CFU·g^-1 to 6.1×l0⁴-5.30×l0⁶ CFU·g^-1, respectively. The range of the Vibrio's in sludge was 0.8×10⁴-2.75×l0⁵CFU·g^-1. Fecal coliforms in water of ponds number four and five were also low, while densities in pond number six were high. As complementary data, bottom sludge densities of these bacteria was very low.Water column heterotrophic bacteria and Bacillus were possibly related (positive linear correlation) to temperature; however, the correlation was not significant (P>0.05). Planktonic Bacillus could be explained by DO concentrations, lgB=l.263+1.7321gX[DO](r=0.835,n=7,P=0.01). Planktonic heterotrophic bacteria were directly linked numbers of the same group in bottom sludge, via lgPHB=-1.503+0.9261gX[SHB](r=0.717,n=7,P<0.05).