Data_Sheet_1_Comparative Analysis of Total and Size-Fractionated Chlorophyll a in the Yellow Sea and Western Pacific.docx

Measurements of different size-fractionated chlorophyll a concentrations (Chl a) of phytoplankton assemblages in situ are vital for advancing our understanding of the phytoplankton size structure and thus the marine biogeochemical cycle. In the present study, we thus made a comparative analysis of total and size-fractionated Chl a in the Yellow Sea (YS) and Western Pacific (WP). Our results suggest that the total Chl a was highly variable in the YS (averaging ~1.02 μg L−1) and was generally 3–4-fold more than that in the WP (averaging ~0.30 μg L−1). The pico-sized Chl a had a significant contribution to total Chl a in the WP (range 75–88%), while the average contributions of the nano-sized and pico-sized Chl a to total Chl a in the YS were 47 and 38%, respectively, suggesting that a majority of the total Chl a in the YS was associated with nano- and picophytoplankton. Moreover, we applied the generalized additive models (GAMs) to explore the relationships between the total Chl a and that contained in each of the three size classes. These GAMs relationships suggested a continuum from picophytoplankton dominated waters to large phytoplankton (cells> 2 μm) domination with increasing Chl a. Finally, we made a comparison of the total Chl a obtained with GF/F filters and that measured from size-fractionated filtration and revealed that their corresponding concentrations are in good agreement, indicating the size-fractionated filtration had no effect on total Chl a determination.</p

DataSheet_1_Exploring the key factors affecting the seasonal variation of phytoplankton in the coastal Yellow Sea.doc

Marine phytoplankton play crucial roles in the ocean’s biological pump and have great impacts on global biogeochemical cycles, yet the knowledge of environmental variables controlling their seasonal dynamics needs to be improved further, especially in the coastal ecosystems. In order to explore the determinants affecting the seasonal variation of phytoplankton, here we conducted three surveys during spring, summer and autumn along the coastal Yellow Sea. Among the phytoplankton community, 49 species of diatoms and 9 species of dinoflagellates were observed in spring, 63 species of diatoms and 10 species of dinoflagellates in summer, and 62 species of diatoms and 11 species of dinoflagellates in autumn. These results thus suggested that there were obvious differences in the number of species across the three seasons, of which diatoms were the most diverse group, followed by dinoflagellates. Additionally, diatoms were the most dominant species of the phytoplankton community and varied largely during different seasons. According to the redundancy analysis, the abundance of phytoplankton community was mainly related to water temperature and dissolved inorganic nitrogen (DIN) during the three seasons, indicating that water temperature and DIN could be the key factors controlling the seasonal variability of phytoplankton community along the coastal Yellow Sea. Also, significant correlations were observed between phytoplankton abundance and heavy metals Zn, As, and Hg during the three seasons, suggesting that these metals also had potential influences on the seasonal dynamics of phytoplankton community in the coastal Yellow Sea.</p

Online Monitoring of Bacterial Growth with an Electrical Sensor

Herein, we developed an automatic electrical bacterial growth sensor (EBGS) based on a multichannel capacitively coupled contactless conductivity detector (C⁴D). With the use of the EBGS, up to eight culture samples of <i>E. coli</i> in disposable tubes were online monitored simultaneously in a noninvasive manner. Growth curves with high resolution (on the order of a time scale of seconds) were generated by plotting normalized apparent conductivity value against incubation time. The characteristic data of <i>E. coli</i> growth (e.g., growth rate) obtained here were more accurate than those obtained with optical density and contact conductivity methods. And the correlation coefficient of the regression line (<i>r</i>) for quantitative determination of viable bacteria was 0.9977. Moreover, it also could be used for other tasks, such as the investigation of toxic/stress effects from chemicals and antimicrobial susceptibility testing. All of these performances required neither auxiliary devices nor additional chemicals and biomaterials. Taken together, this strategy has the advantages of simplicity, accuracy, reproducibility, affordability, versatility, and miniaturization, liberating the users greatly from financial and labor costs

Image_1_Comparative investigation on heterotrophic denitrification driven by different biodegradable polymers for nitrate removal in mariculture wastewater: Organic carbon release, denitrification performance, and microbial community.TIF

Heterotrophic denitrification is widely studied to purify freshwater wastewater, but its application to seawater wastewater is rarely reported. In this study, two types of agricultural wastes and two types of synthetic polymers were selected as solid carbon sources in denitrification process to explore their effects on the purification capacity of low-C/N marine recirculating aquaculture wastewater (NO3−-N 30 mg/L, salinity 32‰). The surface properties of reed straw (RS), corn cob (CC), polycaprolactone (PCL) and poly3-hydroxybutyrate-hydroxypropionate (PHBV) were evaluated by Brunauer–Emmett–Teller, Scanning electron microscope and Fourier-transform infrared spectroscopy. Short-chain fatty acids, dissolved organic carbon (DOC), and chemical oxygen demand (COD) equivalents were used to analyze the carbon release capacity. Results showed that agricultural waste had higher carbon release capacity than PCL and PHBV. The cumulative DOC and COD of agricultural waste were 0.56–12.65 and 1.15–18.75 mg/g, respectively, while those for synthetic polymers were 0.07–1.473 and 0.045–1.425 mg/g, respectively. The removal efficiency of nitrate nitrogen (NO3−-N) was CC 70.80%, PCL 53.64%, RS 42.51%, and PHBV 41.35%. Microbial community analysis showed that Proteobacteria and Firmicutes were the most abundant phyla in agricultural wastes and biodegradable natural or synthetic polymers. Quantitative real-time PCR indicated the conversion from nitrate to nitrogen was achieved in all four carbon source systems, and all six genes had the highest copy number in CC. The contents of medium nitrate reductase, nitrite reductase and nitrous oxide reductase genes in agricultural wastes were higher than those in synthetic polymers. In summary, CC is an ideal carbon source for denitrification technology to purify low C/N recirculating mariculture wastewater.</p