Relative abundance and bacterial composition obtained by pyrosequencing from phycosphere samples in September and October, by phylum.

<p>Phylogenetic classification for the pyrosequencing analysis obtained from Ribosomal Database Project Classifier analyses.</p

Environmental variables at the three sampling times.

<p>Environmental variables at the three sampling times.</p

Organic carbon-utilization conceptual model illustrating the role of bacteria on different-sized aggregates in the cyanobacterial phycosphere.

<p>Organic carbon-utilization conceptual model illustrating the role of bacteria on different-sized aggregates in the cyanobacterial phycosphere.</p

Observed bacterial richness and diversity estimates based on 97% and 95% OTU clusters respectively.

<p>Observed bacterial richness and diversity estimates based on 97% and 95% OTU clusters respectively.</p

Rarefaction analysis of the 16S rRNA gene sequences among phycosphere samples using an evolutionary distance threshold of 3% (i.e., 97% similarity).

<p>Rarefaction analysis of the 16S rRNA gene sequences among phycosphere samples using an evolutionary distance threshold of 3% (i.e., 97% similarity).</p

Pareto-Lorenz curves derived from phycosphere samples in Lake Taihu.

<p>The 16S rRNA gene sequences were divided in OTUs based on a sequence similarity threshold of 97% and the OTUs were ranked from high to low, based on their abundance. The Pareto-Lorenz evenness curve is the plot of the cumulative proportion of OTU abundance (y-axis) against the cumulative proportion of OTUs (x-axis). The <i>Fo</i> index, i.e. the combined relative abundance of 20% of the OTUs, is shown. The 45° diagonal is the Pareto-Lorenz curve of a community with perfect evenness.</p

Principle component analysis of the phycosphere samples including cyanobacterial reads (A) and excluding cyanobacterial reads (B).

<p>The Yue and Clayton measure of dissimilarity between the structures of the communities was estimated and visualized using the dist.shared and pcoa commands of Mother.</p

Temperature effects on calculated Q10 of metabolic processes in freshwater systems.

<p>*Q10 values were calculated from the data in the reference.</p

Temperature and Cyanobacterial Bloom Biomass Influence Phosphorous Cycling in Eutrophic Lake Sediments

<div><p>Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB) settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P) in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC), we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II) and the formation of FeS/FeS₂. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures.</p></div

Iron reduction and sulfate reduction in sediments.

△<p>Data are means ± standard deviation;</p>¶<p>Parentheses indicate the time (day) of the maximum iron reduction rate;</p><p>*ND, not detected;</p>a<p>Significant difference for iron reduction at 25°C and 32°C in unamended sediments (<i>P</i><0.05);</p>b<p>Significant difference for iron reduction at 15°C and 32°C in CBB-amended sediments (<i>P</i><0.05);</p>c<p>Significant difference for iron reduction at 25°C and 32°C in CBB-amended sediments (<i>P</i><0.05);</p>d<p>Sulfate reduction rates in amended sediments at any two respective temperatures show significant difference (<i>P</i><0.05).</p