Abstract: To investigate the effect of tilapia cultivation density on water quality parameters and bacterial diversity,water quality monitoring was carried out. After 30 days of breeding experiment,water samples were collected to detected the diversity and abundance of bacteria though Illumina Miseq 16S rDNA gene sequence,meanwhile histopathological examination was conducted. The results showed that the rearing density of tilapia did not affect liver tissue. With the increase of rearing density,gills presented pathological changes such as twist,enlarged ends and even loss of branchial lobule. The dissolved oxygen content in aquaculture water decreased with the increase of rearing density(P<0.05). The correlation coefficient matrix of water quality parameters and load analysis showed that the nitrate nitrogen and nitrite nitrogen in the water of different culture density groups were moderately correlated. Dissolved oxygen in the low-density and high-density groups was negatively correlated with ammonia nitrogen in medium intensity,while dissolved oxygen in the medium-density group was negatively correlated with ammonia nitrogen. The rearing densities lead to different abundance of bacteria in aquaculture water. The dominant bacteria were Flavobacterium, Sphingomonas, hgcl_clade,and Macrosomonas and so on,and most of them had the ability to degrade pollutants. The above results showed that adequate oxygen supply in medium-culture density of tilapia could promote the degradation of inorganic nitrogen in water,and the combination of effective water treatment could ensure the growth of fish,which could bring the maximum economic effect.

Key words: Tilapia, Stocking density, Water quality, Bacterial diversity, 16S rDNA high-throughput sequencing

CLC Number: 

• S965.1