Restrictive Ecological Conditions On The Growth Of Oscillatoria SP.

Oscillatoria sp. is a common species of cyanphytes in prawn ponds, proliferation of them will destroy the ecological balance of waters, that’s harmful to breeding prawns directly. This paper analysed the effects of environmental condition(temperature illumination intensity、salinity and pH) and nutrient conditions(trace elements:Fe3+、 Mn2+、Cu2+\Zn2+、Mo6+、Co2+, macro elements:N、P、Si4+、Mg2+、Ca2+, vitamins: VB1、VB12、VH) on the growth of Oscillatoria sp. This paper set the restrictive ecological conditions by set chlorophyll-a content and dry weight of Oscillatoria sp. as the growth index, and did range analysis to the results of orthogonal experiments to find the lowest of growth conditions of Oscillatoria sp.. The main results are as follows:1、Analysed the results of single-factors experiments, which shows the conditions that limiting the increase of chlorophyll-a content are temperature:<10℃and>35℃, illumination intensity:<50lxand>1100lx, salinity:<15.0and>35.0, pH:<5.2and>8.6; the conditions that limiting the increase of dry weight are temperature:<10℃, illumination intensity:<50lx, salinity:<22.5and>40.0, pH:<5.2. the temperature of begining growth of Oscillatoria sp. is10℃, illumination intensity50lx, salinity15.0, pH5.2; the most suitable temperature of growth is30℃, illumination intensity600～1100lx, salinity30.0, pH7.3.2、Analysed the results of single-factors experiments, which shows the conditions that limiting the increase of chlorophyll-a content are N concentration:<9.927×10-3mg/L, P concentration:<9.927×10-3mg/L, Fe3+:concentration<5.163×10-3mg/L; the conditions that limiting the increase of dry weight are N concentration:<6.180mg/L, P concentration:<1.985×10-3mg/L, Fe3+:concentration:<2.581×10-4mg/L and25.810mg/L. the N concentration of begining growth of Oscillatoria sp. is6.180mg/L and P1.985×10-3mg/L、Fe3+2.581×10-4mg/L; the most suitable range of N concentration to Oscillatoria sp. is higher than2.361mg/L、and P1.985～9.927mg/L、Fe3+0.516～2.581mg/L3、Analysed the results of single-factors experiments, which shows the conditions that limiting the increase of chlorophyll-a content and dry weight are Mn2+concentration:>27.759mg/L, Cu2+concentration:>0.127mg/L, Zn2+>6.821×10-2mg/L, Co2+concentration:>3.096mg/L, Mg2+concentration:<579.762mg/L. the most suitable range of Mn2+concentration to Oscillatoria sp. is0～2.776mg/L, and Cu2+concentration 0～0.127mg/L、Zn2+concentration0～6.821×10-2mg/L、Co2+concentration0-3.096mg/L.4、The experiments have demonstrated Mo6+、Si4+、Ca2+are not significant factors on increase of chlorophyll-a content and dry weight, can’t limiting the growth of Oscillatoria sp..5、The experiments have demonstrated VB1、VB12、VH are not significant factors on increase of chlorophyll-a content and dry weight, can’t limiting the growth of Oscillatoria sp..6、Analysed the results of orthogonal experiments, which shows the lowest conditions combination of begining growth of Oscillatoria sp. is temperature15℃, illumination intensity600lx, salinity17.5, pH5.5. The strength of the relationship on chlorophyll-a content of the impact is:temperature>pH> salinity> illumination intensity; The strength of the relationship on chlorophyll-a content of the impact is:temperature> salinity> pH> illumination intensity, the conditions of the most suitable for growth of Oscillatoriasp. is temperature25℃, illumination intensity800lx, salinity25.0, pH6.3;so the most possible way to limit the growth of Oscillatoria sp. is drop the salinity lower than15.0.7、Analysed the results of orthogonal experiments, which shows the lowest conditions combination of begining growth of Oscillatoria sp. is N concentration:7.416concentration mg/L, P2.978mg/L, Fe3+concentration2.065mg/L. N、P、Fe3+on the strength of the relationship between chlorophyll-a content and dry weight of the impact is: N>Fe3+>P. the concentration of the most suitable combination for growth of Oscillatoria sp. is N32.962mg/L、P2.978mg/L、Fe3+2.065mg/L, so the effective way to limit the growth of Oscillatoria sp. is control the concentration of N、P、Fe3+down to the lowest conditions.