The effects of commercial microbial agents (probiotics) on phytoplankton community structure in intensive shrimps (litopenaeus.pdf

1、study was conducted to investigate the effects of probiotics on phytoplankton community structure in intensive shrimps (Litopenaeus vannamei) aquaculture ponds and to examine how commercial microbial agents alter the wat

2、er quality and shrimps production. Results show that，commercial microbial agents have potential to diminish harmful algae，retain of beneficially algae such as diatoms and maintain of water quality. Significant impact was

3、 noted between the treated ponds and untreated pondS.The analysis showed that ponds treated with commercial microbial agents had significant impact on the phytoplankton community structure (P<0.05). The phytoplankton pop

4、ulation density of diatoms and Chlorophyta were increased significantly (P<0.05). These findings suggest that the application of the commercial microbial agents had strong positive influence on the changes of phytoplankt

5、on community，increased of beneficially algae，which substantially will improving the primary productivity and water quality of earthen pond ecosystems.A mesocosm experiment was conducted to study the effects of different

6、commercial microbial agents (probiotics) on the phytoplankton community structure in a shrimp (Litopenaeus vannamei) farm located in Yinzhou-Ningbo，Zhejiang Province，China. Qualitative and quantitative analyses of the ph

7、ytoplankton were examined along with physico-chemical parameters in the ponds treated with microbial agents and in the untreated ponds without microbial agentS.A total of 18 well-diversified species of phytoplankton belo

8、nging to Bacillariophyta，Dinoflagellata，Cyanophyta and Chlorophyta were investigated during the study period. The average phytoplankton abundance in the treated ponds (6.08 ×105 cells L-1 in HJW ponds and 7.11 × 105 cell

9、s L-1 in JK27 ponds) was significantly less than that in the control ponds (1.27 × 106 cells L-1，P<0.05). The dominant group in both the treated ponds was Bacillariophyta (70.84％ in HJW and 64.36% in JK27)，whereas the do

10、minant group in the control ponds was Cyanobacteria(37.05%). The analysis showed that the addition of different probiotics significantly increased (P<0.05) the concentration of Coscinodiscus species from Bacillariophyta

11、in the treated ponds (HJW and JK27) and significantly decreased (P<0.05) the concentration of Oscillatoria species than that in the control pondS.None of the water quality parameter results differed significantly between

12、 the treatments (P>0.05). The findings of the present study suggest that the application of commercial probiotics in shrimp farms could positively influence the growth of beneficial algae，such as Bacillariophyta rather t

13、han harmful algae，such as Cyanobacteria，and thus improves the water quality，the health of the shrimp and increases production In order to determine the efficacy of high and low dosage of commercial microbe agent on phyto

14、plankton community structure and nutrient fluxes，Phytoplankton and water quality samples were collected from an intensive shrimp’s (Litopenaeus vannamei) aquaculture farm in Yinzhou –Ningbo from April to June 2013. There

15、 were significant differences (P<0.05) between phytoplankton species composition at the treated ponds and control pondS.The growth rate of beneficial algae in treated ponds with high dosage was 51%and lower dosage was 37

16、%which was higher than in control 22%，while the nutrients fluxes under treated ponds were lower than those in control ponds (P>0.05). Diatoms and Cyanophyta showed intensive variations and reached peak values (bloom) tow

17、ard the final culture days which response to increased organic input due to the shrimps farming. Abundance of Cynobacteria were significantly higher (6.34 ×105 cells L-1 (P<0.05) in the control compared with the treated

18、ponds (2.66 ×105 cells L-1 in HD ponds and 3.36 ×105 cells L-1 in LD ponds at the final dayS.Organic nutrient fluxes (NH4+，NO2-+NO3- and PO43- fluxes were measured using chamber incubations at laboratory. The concentrati

19、ons of total Organic nutrient fluxes NH4+，NO2-+NO3-and PO43-) didn’t differ significantly among months and with the treatments; however displayed minor variation (P>0.05). NH4+，PO43-，TP and Chl ɑ fluxes exhibit positive

20、correlations with phytoplankton density. The results obtained in this study imply that，the application of high dosage of commercial probiotics in shrimps aquaculture activities had led in redistribution of beneficial alg