Study On Abundance And Diversity Of Virioplankton In Scallop Farming Around Qinhuangdao

Aquaculture activity has serious impact on marine environment, but there is alack of comprehensive awareness about that, especially the effect of aquacultureactivity on ultraplankton such as virioplankton. This paper studied the abundance anddistribution characteristics of virioplankton and its host by flow cytometry and thediversity of virioplankton by metagenomic in Qinhuangdao scallop cultivating area.Then comparative research on the abundance and diversity of virioplankton in culturezone and non-culture zone, in order to study the influence of aquaculture activity onvirioplankton.In the cultured area, the average value of virioplankton abundance is8.73×105cells/ml in spring,1.05×106cells/ml in summer,1.91×106cells/ml in fall,6.13×105cells/ml in winter. The abundance of virioplankton decreases with seasons insequence of fall, summer, spring, winter. Total abundance was greatest in autumn, butnon-difference of four seasons. In the cultured area, the abundance of Synechococcusranged from9.00×102cells/ml to7.07×105cells/ml. Total abundance was greatest inautumn. There was obvious difference between autumn and other seasons. Theabundance of Picoeukaryote ranged from5.80×102cells/ml to3.23×105cells/ml.When the red tide outbreak in summer, the abundance of Picoeukaryote obvioushigher than other seasons reached3.23×105cells/ml. The abundance of heterotrophicbacteria ranged from3.10×105cells/ml to3.79×106cells/ml. Total abundance wasgreatest in autumn. The abundance of heterotrophic bacteria in summer and autumnwas higher than spring and winter. The correlation analysis shows the abundance ofvirioplankton was positively correlated with heterotrophic bacteria in spring andwinter and negative correlated with Picoeukaryote in summer and negative correlatedwith Synechococcus in fall. The results showed that aquaculture activity makesvirioplankton significant correlation with its host which had the highest abundance in4seasons. Aquaculture activity affects the abundance and distribution of Synechococcus, Picoeukaryote and heterotrophic bacteria. Total abundance ofSynechococcus was greatest of fall in culture zone, but of summer in non-culture zone.The abundance of Picoeukaryote in culture zone is higher than in non-culture zone, insummer. The abundance of heterotrophic bacteria in summer and autumn was higherthan spring and winter in culture zone, but no significant seasonal variation innon-culture zone. The principal component of ultraplankton was heterotrophicbacteria in cultured area, however, in non-cultured area it was Phytoplankton.Metagenomic studies show that the paper detected2618virus ORFs, includingbacteeriophage (21%), cyanophage(11%), phycovirus(20%), animal virus(0.8%) andunknown virus(47.2%) in summer in culture zone. Myoviridae is the dominant groupof bacteriophage and cyanophage, detected23and11species. The phycovirus iscomposed of Prasinovirus, Chlorovirus, Coccolithovirus and Phaeovirus, no detectedPrymnesiovirus and Raphidovirus. Six species of animal virus was detected, in whichBovine viral diarrhea virus1and Macacine herpesvirus5is terrestrial animal virus.The paper detected1574virus ORFs, including bacteeriophage (16%),cyanophage(24%), phycovirus(5%), animal virus(0.4%) and unknown virus(54.6%)in summer in non-culture zone. Myoviridae is the dominant group of bacteriophageand cyanophage, detected13and14species. The phycovirus is only composed ofPrasinovirus, Chlorovirus and Phaeovirus. Six species of animal virus was detected,in which Diachasmimorpha longicaudata entomopoxvirus and Cotesia congregatabracovirus is insect virus. The largest percentages of hits to viral genes of knownfunction were to those involved in Replication and Repair or Nucleotide Metabolism.The results showed that aquaculture activity was elevated the diversity of phycovirusand bacteeriophage. Aquaculture activity has impact on the diversity of cyanophage ofseasonal. Aquaculture activity makes the terrestrial animal virus exists invirioplankton, such as Bovine viral diarrhea virus1and Macacine herpesvirus5.