Heterotrophic flagellates (HFs) are important members of the aquatic microbial food web. However, information on their spatial patterns in relation to eutrophication is limited. Here, we examined the ...composition and spatial distributions of HFs (<3 μm) in subtropical coastal waters of different trophic status by re-analyzing two previously published small subunit rDNA pyrosequence datasets using information from the newly launched Protist Ribosomal Reference database (PR²). Whereas the contributions of different major clades composing the Marine Stramenopiles (MASTs), picobiliphytes and Chrysophyceae were found relatively comparable between the stations, contrasting compositions of the Marine Alveolates (MALV) groups I and II were observed. The high and relatively stable contribution of MAST-1, -3 and -7 among the MASTs in both stations suggest their importance as bacterial grazers in coastal waters, irrespective of trophic status. By contrast, the dominance of clades 3, 5 and 14 of MALV II in the eutrophic station implies their importance in regulating the dinoflagellate population at the site. Our study provides insights into the ecological importance of different HF groups in eutrophic coastal ecosystems.
A distributed Bragg reflector (DBR) composed of Y 2 O 3 -doped HfO 2 (YDH)/SiO 2 layers with high reflectivity spectrum centered at a wavelength of ~240 nm is fabricated using radio-frequency ...magnetron sputtering. Before the DBR deposition, optical properties for a single layer of YDH, SiO 2 , and HfO 2 thin films were studied using spectroscopic ellipsometry and spectrophotometry. To investigate the performance of YDH as a material for the high refractive index layer in the DBR, a comparison of its optical properties was made with HfO 2 thin films. Due to larger optical bandgap, the YDH thin films demonstrated higher transparency, lower extinction coefficient, and lower absorption coefficient in the UV-C regime (especially for wavelengths below 250 nm) compared to the HfO 2 thin films. The fabricated YDH/SiO 2 DBR consisting of 15 periods achieved a reflectivity higher than 99.9% at the wavelength of ~240 nm with a stopband of ~50 nm. The high reflectivity and broad stopband of YDH/SiO 2 DBRs will enable further advancement of various photonic devices such as vertical-cavity surface-emitting lasers, resonant-cavity light-emitting diodes, and resonant-cavity photodetectors operating in the UV-C wavelength regime.
The diel behavior and feeding ecology of three coexisting species of chaetognaths in two shallow subtropical bays in the northeastern part of Hong Kong were studied in summer 2005 and winter ...2005-2006. Average densities of adult Flaccisagitta enflata, Aidanosagitta delicata and Aidanosagitta neglecta ranged from 21 to 48 ind. m super(-3) in the semi-enclosed Tolo Harbour, but densities of the two Aidanosagitta species were low in Mirs Bay, which is deeper and opens into the South China Sea. Adult F. enflata, the largest of the three species, exhibited the most pronounced diel vertical migration (DVM) and diel feeding rhythm. The smaller juvenile F. enflata and adult A. delicata did not exhibit DVM. Although copepods were the most abundant component of the mesozooplankton, they were not preferred prey of chaetognaths. Predation impacts on copepods were generally <0.3% of the standing stock. Larvaceans, on the other hand, were highly preferred, with predation impact as high as >30%. As prey abundances in Tolo Harbour could be >9 10 super(4) ind. m super(-3), there was no evidence of resource partitioning behavior by the coexisting chaetognaths.
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