Document Type : Research Paper
Authors
1
Assistant Professor, Department of Fisheries, Faculty of Natural Resources, University of Zabol, Zabol, Iran.
2
Assistant Professor, Department of Fisheries, Payame Noor University, Gorgan, Iran.
3
Ph.D. Student, Department of Fisheries, Faculty of Fisheries and Environment, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
4
Assistant Professor, Department of Environmental Sciences, Faculty of Natural Resources, University of Zabol, Zabol, Iran.
Abstract
In general, the relationship between zooplankton and bacteria is important to increase the productivity of live food production. The present study was done with the objective to investigate the predominant bacteria in Daphnia pulex (Cladocera) and Apocyclops dengizicus (Copepoda) fed with manure (chicken and sheep manure at rates of 1:1), vegetables (Fenugreek + Thymus + Savory at rates of 1: 1: 1 weight ratio) and Oscillatoria africanum, the effect of culture medium on zooplankton density and medium BOD and COD. The results showed that different diets had a significant effect on the D. pulex and A. dengizicus density, bacterial populations and biochemical medium properties (BOD and COD). The dominant bacteria in the mediums enriched with manure and vegetables for D. pulex were Acinetobacter sp. and in the medium containing O. africanum, Aeromonas sp. was dominant. In the A. dengizicus cultivation medium enriched with manure, vegetables and O. africanum, the Neisseri sp., Enterobacteria sp. and Alcaligenes sp. were dominant, respectively. Maximum microbial population in medium was measured in D. pulex fed manure (11×104 cells/ml) and A. dengizicus fed with O. africanum (12×103 cells/ml). The highest density of D. pulex (289±11.9) and A. dengizicus (188±19.2) were calculated in the medium enriched with O. africanum, while the least density was counted when manure was used. BOD and COD showed maximum amount in D. pulex and A. dengizicus fed with vegetables (101 and 298 mg/l, respectively). The results showed that there was no significant correlation between D. pulex density and bacterial population, but there was a significant correlation between bacterial populations and A. dengizicus density. Also, there was a significant correlation between zooplankton density (D. pulex and A. dengizicus) and biochemical medium parameters (BOD and COD). In general, it can be concluded that in order to achieve the highest density of D. pulex and A. dengizicus, the use of culture media containing O. africanum has a higher efficiency. Also, zooplankton species and diet used during breeding period affect the type of bacteria and their population density.
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