Picocyanobacteria Prochlorococcus and Synechococcus are abundant in the global oceans and subject to active viral infection. In this study, the genetic diversity of picocyanobacteria and the genetic diversity of cyanopodoviruses were synchronously investigated along water columns in the equatorial Indian Ocean and over a seasonal time course in the coastal Sanya Bay, South China Sea. Using the 16S-23S rRNA internal transcribed spacer (ITS)-based clone library and quantitative PCR (qPCR) analyses, the picocyanobacterial community composition and abundance were determined. Sanya Bay was dominated by clade II Synechococcus during all the seasons, and a typical population shift from high-light-adapted Prochlorococcus to low-light-adapted Prochlorococcus was found along the vertical profiles. Strikingly, the DNA polymerase gene sequences of cyanopodoviruses revealed a much greater genetic diversity than we expected. Nearly one-third of the phylogenetic groups were newly described here. No apparent seasonal pattern was observed for the Sanya Bay picocyanobacterial or cyanopodoviral communities. Different dominant cyanopodovirus lineages were identified for the coastal area, upper euphotic zone, and middle-to-lower euphotic zone of the open ocean. Diversity indices of both picocyanobacteria and cyanopodoviruses were highest in the middle euphotic zone and both were lower in the upper euphotic zone, reflecting a host-virus interaction. Cyanopodoviral communities differed significantly between the upper euphotic zone and the middle-to-lower euphotic zone, showing a vertical pattern similar to that of picocyanobacteria. However, in the surface waters of the open ocean, cyanopodoviruses exhibited no apparent biogeographic pattern, differing from picocyanobacteria. This study demonstrates correlated distribution patterns of picocyanobacteria and cyanopodoviruses, as well as the complex biogeography of cyanopodoviruses.IMPORTANCE Picocyanobacteria are highly diverse and abundant in the ocean and display remarkable global biogeography and a vertical distribution pattern. However, how the diversity and distribution of picocyanobacteria affect those of the viruses that infect them remains largely unknown. Here we synchronously analyzed the community structures of cyanopodoviruses and picocyanobacteria at spatial and temporal scales. Both spatial and temporal variations of cyanopodoviral communities can be linked to those of picocyanobacteria. The coastal area, upper euphotic zone, and middle-to-lower euphotic zone of the open ocean have distinct cyanopodoviral communities, showing horizontal and vertical variation patterns closely related to those of picocyanobacteria. These findings emphasize the driving force of host community in shaping the biogeographic structure of viruses. Our work provides important information for future assessments of the ecological roles of viruses and hosts for each other.
We studied species diversity and enzyme activities of fungi from 11 marine sediment samples in the South China Sea.Salt-tolerant fungi were isolated by a dilution-plate method, and their diversity was studied based on fungal morphology and rDNA ITS (Internal Transcribed Spacer) sequences. Enzyme activities were screened by six special selective media.A total of 1689 strains of salt-tolerant fungi were isolated. Morphology and ITS sequence analysis identified these fungi to 41 species of 15 described genera, of which Aspergillus sp. and Penicillium sp. were the dominant populations. Studies on enzyme activities of 41 sequenced strains showed that 8 strains produce cellulase, 9 strains produce amylase, 5 strains produce compound enzyme, 16 strains produce protease, 3 strains produce lipase and no strain produce chitonsanase. Acrodontium sp. 8m and Aspergillus sp. 86b produced the most multiple enzymes, while Penicillium sp. 41m produced comparatively higher protease.There were abundant salt-tolerant fungi from marine sediment samples in the South China Sea, and more strains had enzyme activities.
Coral harbor diverse and specific bacteria play significant roles in coral holobiont function. Bacteria associated with three of the common and phylogenetically divergent reef-building corals in the South China Sea, Porites lutea, Galaxea fascicularis and Acropora millepora, were investigated using 454 barcoded-pyrosequencing. Three colonies of each species were sampled, and 16S rRNA gene libraries were constructed individually. Analysis of pyrosequencing libraries showed that bacterial communities associated with the three coral species were more diverse than previous estimates based on corals from the Caribbean Sea, Indo-Pacific reefs and the Red Sea. Three candidate phyla, including BRC1, OD1 and SR1, were found for the first time in corals. Bacterial communities were separated into three groups: P. lutea and G. fascicular, A. millepora and seawater. P. lutea and G. fascicular displayed more similar bacterial communities, and bacterial communities associated with A. millepora differed from the other two coral species. The three coral species shared only 22 OTUs, which were distributed in Alphaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, Chloroflexi, Actinobacteria, Acidobacteria and an unclassified bacterial group. The composition of bacterial communities within each colony of each coral species also showed variation. The relatively small common and large specific bacterial communities in these corals implies that bacterial associations may be structured by multiple factors at different scales and that corals may associate with microbes in terms of similar function, rather than identical species.
Drought is a damaging and costly natural disaster that will become more serious in the context of global climate change in the future. Constructing a reliable drought risk assessment model and presenting its spatial pattern could be significant for agricultural production. However, agricultural drought risk mapping scientifically still needs more effort. Considering the whole process of drought occurrence, this study developed a comprehensive agricultural drought risk assessment model that involved all risk components (exposure, hazard, vulnerability and mitigation capacity) and their associated criteria using geospatial techniques and fuzzy logic. The comprehensive model was applied in Songnen Plain to justify its applicability. ROC and AUC techniques were applied to evaluate its efficiency, and the prediction rate was 88.6%. The similar spatial distribution of water resources further verified the model’s reliability. The southwestern Songnen Plain is a very-high-risk (14.44%) region, determined by a high vulnerability, very high hazardousness and very low mitigation capacity, and is the region that should be paid the most attention to; the central part is a cross-risk region of high risk (24.68%) and moderate risk (27.28%) with a serious disturbance of human agricultural activities; the northeastern part is a dry grain production base with a relatively optimal agricultural production condition of very low risk (22.12%) and low risk (11.48%). Different drought mitigation strategies should be adopted in different regions due to different drought causes. The findings suggest that the proposed model is highly effective in mapping comprehensive drought risk for formulating strong drought mitigation strategies and could be used in other drought-prone areas.
Bivalve shellfish farming is expected to be performed as the effective mitigator of the growing pressure for global animal protein demand.Carbon emission reduction in the whole farming process of the bivalve shellfish has great potential in reducing carbon emissions in food production in the future.However, the hatchery stage of oyster, with high energy input, may be a high carbon emission process and necessitates effective carbon emission reduction.This study uses life cycle assessment (LCA) to analyze the carbon footprint of the farming of Pacific oyster (Crassostrea gigas), a shellfish with the largest farming yield in the world, in Fujian province in China.The results show that the total carbon footprint, from cradle to gate is 70.81 kgCO2-eq/tonne fresh oyster, which suggested that oyster farming perform favorably against livestock farming for protein products and can justifiably be promoted as a lowcarbon food product.Hatchery culture contributed 62.2% of the total carbon emission.The feed production in the hatchery culture stage, account for about 2.27 % of carbon emission, were not the major emission factor.Carbon emission form energy consumption and material inputs are about half and half.The carbon footprint of Pacific oyster can be reduced by employing energyconserving transport technology and utilizing renewable energy.The improvements could be helpful for sustainable production of Pacific oyster farming.
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