مصطفی آرمنده

Cyanobacterial blooms cause huge and irreparable financial losses to fish farmers every year. One of the most effective methods for managing water cyanobacterial bloom is biological control by adding pathogenic agents to break down cyanobacterial cells. Therefore, this study investigated the possibility of using Pseudomonas putida bacteria to control the bloom of cyanobacteria Chroococcus sp., Oscillatoria sp., Microcystis sp. and Gloeocapsa sp., isolated from fish Culture ponds was done in the laboratory. The results of this study showed that Pseudomonas putida bacteria have a significant effect on controlling all 4 cyanobacterial species. So, for the cyanobacterium Chroococcus sp. In the experimental group containing 106 CFU/ml of Pseudomonas putida bacteria, there was a moderate 80.7% reduction and also in the group containing 104 CFU/ml of this bacterium, there was 63.1% reduction compared to the control group models on the 10th day. Also, for the cyanobacterium Oscillatoria sp. at the 10th day, 78.9% reduction occurred in 104 CFU/ml and 87.7% in 106 CFU/ml. Next, for the cyanobacterium Microcystis sp. On the tenth day, there was 61.7 percent decrease in the group containing 104 CFU/ml and 70.5 percent decrease in the group containing 106 CFU/ml of Pseudomonas putida bacteria. Finally for the cyanobacterium Gloeocapsa sp. A decrease of 72.3% was observed in the experimental group containing 104 CFU/ml and an 83% decrease in the group containing 106 CFU/ml. Although the control group show an increase of 37-78 percent (P˂0.05). The results of this research showed that the bacterium Pseudomonas putida has a high efficiency in controlling the bloom of cyanobacteria.

This research aimed to evaluate the spatial patterns of water quality and its controlling factors in the Mazandaran coastal ecosystem during winter using the multivariate analysis methods.

Water quality parameters such as nutrients, temperature, conductivity, salinity, DO, pH, chlorophyll-a and turbidity were measured monthly in 16 stations (44 layers) along 4 transects (Amirabad, Babolsar, Noushahr and Ramsar). To evaluate the data, several multivariate statistical methods were used including discriminant function analysis, cluster and factor analysis as well as correlation test.

Results of cluster analysis showed that the sampling sites (44 layers) were classified into 4 groups. Based on discriminant analysis, 93.20% of the sampling sites correctly classified. Factor analysis extracted 4 principal components that explained 74.05% of the total variance. Based on these analyses, organic phosphorus, organic nitrogen, turbidity, chlorophyll-a and temperature were the most effective parameters on the spatial variation of water quality.

This study suggested that the number of sampling locations could be reduced to 3 transects including Amirabad, Babolsar and west coasts (Noushahr and Ramsar) and 2 stations (one surface layer and one deep layer). Transport of nutrients from land, sea floor and fish cage culture were the most effective factors on spatial patterns of water quality in Mazandaran coasts. Based on the results, multivariate statistical methods are also introduced as one of the useful methods for identifying the spatial pattern of water quality.

The bio-availability of phosphorus for primary producers is reduced mainly due to the formation of complex with cations and organic matter in warm-water fish ponds. Therefore, the most important new approaches for increasing water-soluble phosphate that are consistent with the principles of sustainable agriculture are the use of phosphate solubilizing and mineralizing bacteria (PSB). For this purpose, sampling of the sediment of warm-water fish ponds in central regions of Mazandaran province was carried out. Isolation and identification of bacteria were performed using by National Botanical Research Institute (NBRIP) medium and 16s rRNA gene sequence. The ability of strains to grow in the range of environmental parameters of warm-water fish ponds was also evaluated. In the present study, a total of 64 PSB strains were isolated, among these, 11 stronger PSBs were including Pseudomonas taiwanensis (Persian1 and Persian2), P. putida (Persian3), P. umsongensis (Persian4 and Persian5), P. kilonensis (Persian6), P. frederiksbergensis (Persian7, Persian8 and Persian9), P. deceptionensis (Persian10) and Acinetobacter lactucae (Persian11) had the best performance in solubilizing insoluble phosphates. The results showed that these strains have a high ability to dissolve insoluble phosphate compounds and grow well under the environmental parameter of warm-water fish ponds.

The production and use of phosphorus biofertilizers in agriculture began several decades ago, and the status of these fertilizers has now become widespread, that global revenues from the sale of biofertilizers in the year 2022 were estimated reach to 1.66 billion dollar that 13.9 percent of that for phosphorous biofertilizers. However, the production and consumption of phosphorous biofertilizers in the aquaculture sector has been less widely considered. The bioavailability of phosphorus for primary producers in warm-water fishponds is mainly reduced by the formation of complex with cations and organic matter. Therefore, in order to increase water soluble phosphorus, the use of phosphorus solubilizing microorganisms as a biofertilizer is pivotal. Phosphorus solubilizing microorganisms release phosphorus from insoluble phosphorus sources via production of organic acids and various enzymes. The application of phosphate biofertilizers to produce fishes reduces the use of chemical phosphorus fertilizers and produce organic products, cost effective and preserve the environment.