Xiubao Li

Polyoxygenated Sterols from the South China Sea Soft Coral Sinularia sp.

Chemical investigation of the ethanol extract of soft coral Sinularia sp. collected from the South China Sea led to the isolation of three new polyoxygenated sterols, (3S,23R,24S)-ergost-5-ene-3β,23α,25-triol (1), (24S)-ergostane-6-acetate-3β,5α,6β,25-tetraol (2), (24S)-ergostane-6-acetate-3β,6β,12β,25-tetraol (3) together with three known ones (4–6). The structures, including relative configurations of the new compounds (1–3), were elucidated by detailed analysis of spectroscopic data (IR, UV, NMR, MS) and by comparison with related reported compounds. The absolute configuration of 1 was further determined by modified Mosher’s method. Compound 5 exhibited moderate cytotoxicity against K562 cell line with an IC50 value of 3.18 μM, but also displayed strong lethality toward the brine shrimp Artemia salina with a LC50 value of 0.96 μM.

Coral bleaching caused by an abnormal water temperature rise at Luhuitou fringing reef, Sanya Bay, China

Luhuitou fringing reef, which has been seriously affected by human activities and terrestrial runoff, has degraded quickly in recent decades. However, direct impact by hyperthermal stress has probably been minimal because of the influence of the Qiongdong upwelling in summer. Seawater temperature anomalies in 2010 resulted in mean monthly seawater temperatures in summer to be 1–2°C higher than in the same period of the 3 preceding years. Moderate coral bleaching at Luhuitou fringing reef was observed in the summer of 2010 due to high thermal stress. Montipora was the most susceptible taxon, whereas Galaxea fascicularis and Pocillopora damicornis were among the least susceptible taxa. Mortality of Montipora was 21.7%, whereas for the remaining taxa it was less than 5%. No mortality was observed for tabular Acropora, G. fascicularis, P. damicornis, Favites and Leptoria. Most taxa showed relatively high bleaching in larger colonies compared with that in smaller ones. Juvenile coral colonies showed less bleaching (3%) than adult coral colonies (28%). Our study suggested that although most taxa in the survey area might recover from this moderate coral bleaching episode, coral reproduction in the year following bleaching may be adversely affected.

Steroids of soft coral Scleronephthya sp. from the South China Sea

0009-3130/12/4802-0341 2012 Springer Science+Business Media, Inc. 1) Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, P. R. China, e-mail: changyun@ouc.edu.cn; 2) South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510000, P. R. China; 3) KAUST Global Academic Partnership Program, Section of Marine Ecology and Biotechnology, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, P. R. China. Published in Khimiya Prirodnykh Soedinenii, No. 2, March–April, 2012, pp. 306–307. Original article submitted December 27, 2010. Chemistry of Natural Compounds, Vol. 48, No. 2, May, 2012 [Russian original No. 2, March–April, 2012]

In search of a Si/SiGe THz quantum cascade laser

While electroluminescence has been demonstrated at terahertz frequencies from Si/SiGe quantum cascade emitters, to date no laser has been achieved due to poor vertical confinement of the optical mode. A method of increasing the vertical confinement of the optical mode for a Si/SiGe quantum cascade laser is demonstrated using silicon-on-silicide technology. Such technology is used with epitaxial growth to demonstrate a strain-symmetrised 600 period Si/SiGe quantum cascade interwell emission and the polarisation is used to demonstrate the optical confinement. Electroluminescence is demonstrated at /spl sim/3 THz (/spl sim/100 /spl mu/m) from an interwell quantum cascade emitter structure. Calculated model overlap and waveguide losses for ridge waveguides are comparable to values from GaAs quantum cascade lasers demonstrated at terahertz frequencies.

Can private management compensate the ineffective marine reserves in China

Marine reserves (MRs) have emerged as a preferred method to protect coral reefs from overfishing and human disturbance. However, due to ineffective enforcement by governments, many MRs have been reduced to mere “paper parks” which fail to achieve conservation goals. This is especially true in countries such as China where compliance is low and resources dedicated to enforcement may be scarce. Privately managed marine reserves (PMMRs) may be effective in areas where government enforcement is lacking. To determine if PMMRs are a viable alternative strategy to protect coral reefs, we surveyed and compared fish assemblages and coral coverage in national MRs in Sanya, China to areas of reef privately leased to and managed by dive operators and hospitality industries. We found higher fish abundances and fish sizes in PMMR sites than in MR sites. However, while PMMRs are protected from fishing, other human impacts such as marine debris and illegal coral collection were evident in most tourist sites. Despite protection, long-term monitoring data of PMMRs revealed that in recent years, fish abundances have slightly recovered but species richness has not, indicating the need for a more comprehensive coral reef management plan. We strongly recommend coupling PMMRs with expertise supported regulations as an alternative coral reef management strategy in China.

Long-term variations in oxygen in sub-tropical coastal waters: Influence of sewage effluent

The increase in population in the Pearl River delta region has increased domestic sewage and industrial discharges, which influences biogeochemical (e.g. carbon dioxide release) and environmental (e.g. oxygen depletion) conditions. Dissolved oxygen and dissolved inorganic carbon concentrations along with salinity, temperature, pH, and chlorophyll a at the surface were collected during seven cruises at eight stations in different months in 2005–2006 to document the seasonal influence of anthropogenic inputs on dissolved oxygen in different areas of Hong Kong waters. Long-term data during 1997–2006 were used to assess air-sea exchange of dissolved oxygen. Near the Pearl River estuary, dissolved oxygen was undersaturated, while partial pressure carbon dioxide was oversaturated, which indicated that Pearl River estuary influenced waters were heterotrophic and represented net sources of carbon dioxide to the atmosphere. In Victoria Harbour, where there was greater sewage effluent influence, however, the degree of dissolved oxygen undersaturation was even more than the Pearl River estuary influenced waters throughout the year. In contrast, the eastern waters, where there was less influence of anthropogenic inputs, showed seasonal variability: undersaturation of dissolved oxygen (∼90%) in the dry season shifting to slight oversaturation (∼105%) in the wet season. The monthly average air-sea influx of oxygen decreased by ∼50 to 200 mmol m−2 d−1 in the wet season relative to that in the dry season in Victoria Harbour, which was coupled with an increase in chlorophyll a from the dry to wet season. These findings are important in understanding why the eutrophication impact from nutrient enrichments in Hong Kong waters is not as severe as one would expect, and also how sewage effluent influences biogeochemical processes of dissolved oxygen and carbon in coastal waters.

Black coral as a new environmental recorder: The lead profiles in coral skeletons over the past century

Lead (Pb) is a typical heavy metal pollutant in the environment, and most Pb contamination comes from human activities. In the present work, the Pb contents of two black coral specimens (Cirrhipathes spp.) collected from the northern South China Sea were measured by synchrotron radiation micro X-ray fluorescence (SR μ-XRF) analysis with 2.5 μm resolution. The results showed that sample SY-1 from the Sanya Bay (near the continent) exhibited higher Pb levels and greater fluctuations than sample XS-1 from the Xisha Islands (off the continent), reflecting the influence of terrestrial input and atmospheric deposition in coastal surface seawater. The present work also demonstrated that the Pb profile in black coral nearshore was highly influenced by human activities, mainly by war and economic development. Thus, black coral may serve as a new potential environmental Pb recorder with SR μ-XRF analytical technology.