Identification of surface water quality along the coast of Sanya, South China Sea

<p>Two cruises were carried out in the representative months of the dry and wet seasons.During spring, sampling was carried out in May. During autumn, sampling was carried out in November.There are 27 stations where we sampled the surface layers waters.Nutrients (NH4-N, NO3-N, NO2-N and PO4-P), COD, total suspended matter (TSM) and Chl-awere tested according to “The specialties for marine monitoring” (GB17378.4-1998, China). Dissolved oxygen (DO) was determined with the method of Winkler titration. Surface water was filteredthrough 0.45μmfilter membrane and stored in a PVCbottle at 4 ℃ prior to analysis. Heavy metals (As, and Hg) were analyzed on Atomic fluorescence photometer . Heavy metals (Cu, Zn,Pb, and Cd)were analyzed onMultifunction polarography.</p

Spatial and temporal variabilities of Chl-a (a) and boxplot (b) along stations in the coast of Sanya.

<p>Spatial and temporal variabilities of Chl-a (a) and boxplot (b) along stations in the coast of Sanya.</p

Dendrogram based on Ward’s method of clustering for 54 stations.

<p>Dendrogram based on Ward’s method of clustering for 54 stations.</p

Spatial and temporal variabilities of (a) As, (b)Hg, (c)Zn, (d) Cd, (e) Pb, and (f)Cu in surface water along stations in the coast of Sanya.

<p>Spatial and temporal variabilities of (a) As, (b)Hg, (c)Zn, (d) Cd, (e) Pb, and (f)Cu in surface water along stations in the coast of Sanya.</p

Monitoring stations along the coast of Sanya.

<p>Monitoring stations along the coast of Sanya.</p

Descriptive statistics of water quality parameters and the one-way analysis of variance for difference between May and November.

<p>*The significance level (p<0.05) is denoted in bold. “-”denotes value below the limit of detection.</p><p>Descriptive statistics of water quality parameters and the one-way analysis of variance for difference between May and November.</p

Spatial and temporal variabilities of temperature (a) and boxplot (b) along stations in the coast of Sanya.

<p>Spatial and temporal variabilities of temperature (a) and boxplot (b) along stations in the coast of Sanya.</p

Linear correlation coefficients of water quality parameters.

<p>*The significance level (p<0.05) is denoted in bold.</p><p>Linear correlation coefficients of water quality parameters.</p

The loadings of variables (a) and scores (b) of the monitoring stations for the first two PCs, respectively.

<p>The number denotes the station number; the letter denotes the variable. The uppercase M and N denote the sampling time in May and November, respectively.</p

Genetic Diversity of Bacterial Communities and Gene Transfer Agents in Northern South China Sea

<div><p>Pyrosequencing of the 16S ribosomal RNA gene (rDNA) amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS) and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS) than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA) major capsid gene (<i>g5</i>) was investigated. Four <i>g5</i> gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen <i>g5</i> clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of <i>g5</i> sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS), temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments.</p></div