Regional and temporal changes in bivalve diversity off the south coast of Portugal

From 2000 to 2006, a total of 75 bivalve species were identified, varying from 29 (spring 2001) to 54 species (spring 2005) per year. Seasonal tendencies in diversity varied according the year, thus the interpretation of long-term and regional scales is essential before drawing any conclusions in other studies. Richness and diversity consistently decreased with depth and increased with sediment grain size (from low in very coarse sand to high in coarse silt). Diversity decreased progressively from 3 to 16 m depth, thus the harsher shallower environments (due to waves and tidal air exposure) showed greater diversity than the most stable areas. Communities in finer sediments were more diverse than those in coarser sand. Evenness showed patterns opposite to diversity, overall.Diversity and evenness maps (produced with multivariate universal kriging), showed that most geographic areas with greater diversity were farer from river outflows and wastewater treatment plants. Two types of geographic pattern were observed: areas with persistently greater bivalve diversity through time and areas that changed locally from year to year. This spatial analysis can be used to establish priority conservation areas for management purposes, and to analyse the persistency of regional diversity patterns. The area with most habitat heterogeneity (Sotavento) corresponded to greatest diversity.There was a positive relationship between Spisula solida and Chamelea gallina landings and bivalve diversity 2 years and 1 year later, respectively. Possibly, local fisheries, by selectively withdrawing the commercial numerically dominant species from the ecosystem, increased diversity 1 to 2 years later, as the ecological niches of the dominants are quickly filled by several other species thereby creating a more even community. On regional scales, no significant impact was found on long-term bivalve diversity in local fisheries,     

Information for Authors

<正>The Journal of Ocean University of China(Oceanic and Coastal Sea Research)is a comprehensive academic quarterly sponsored by the Ocean University of China,published one volume per year.This journal is devoted to the publication of the theoretical and applied research     

Acta Geologica Sinica （English Edition） Calls For Submission of Review Papers

正Acta Geologica Sinica(English Edition)is a bimonthly,SCI-indexed academic journal produced by the Geological Society of China.Having an impact factor ranging from 1.5 to 2.15,it has long been indexed by many international databases and websites,such as SCI,CA,BIG,etc.Internationally,the journal cooperates with John WileySons Co.Ltd     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Performance of the stereoscopic system of the HEGRA imaging air erenkov telescopes: Monte Carlo simulations and observations

Based on the Monte Carlo simulations we have studied the performance of the HEGRA system of imaging air http://www.sciencedirect.com/cache/MiamiImageURL/B6TJ1-3WV9GV8-1-1/0?wchp=dGLzVzb-zSkWA" alt="Image" title="Image" style="vertical-align:bottom" border="0" height=15 width="11"/> erenkov telescopes (IACTs) in its present configuration of 4 IACTs as well as in its future final configuration of 5 IACTs. Here we present the results on the basic characteristics of the IACT system which are used in the standard data analysis procedure, i.e., the collection areas, the detection rates, the angular resolution, the energy resolution, and the γ/hadron-separation efficiency. By comparing several key Monte Carlo predictions with experimental results it is possible to check the accuracy of the simulations. The Monte Carlo results concerning hadron-nuclear showers are tested with the recorded cosmic ray events and the results concerning photon-induced showers are tested with a large data sample of γ-rays observed from BL Lac object Mkn 501 during its high flaring activity in 1997. Summarizing the simulations and current observations we give the basic recommendations of using the instrument and the major values of its sensitivity.     

A numerical study of swash flows generated by bores

The dynamic processes of bore propagation over a uniform slope are studied numerically using a 2-D Reynolds Averaged Navier–Stokes (RANS) solver, coupled to a non-linear k − ε turbulence closure and a volume of fluid (VOF) method. The dam-break mechanism is used to generate bores in a constant depth region. Present numerical results for the ensemble-averaged flow field are compared with existing experimental data as well as theoretical and numerical results based on non-linear shallow water (NSW) equations. Reasonable agreement between the present numerical solutions and experimental data is observed. Using the numerical results, small-scale bore behaviors and flow features, such as the bore collapse process near the still-water shoreline, the ‘mini-collapse’ during the runup phase and the ‘back-wash bore’ in the down-rush phase, are described. In the case of a strong bore, the evolution of the averaged turbulence kinetic energy (TKE) over the swash zone consists of two phases: in the region near the still-water shoreline, the production and the dissipation of TKE are roughly in balance; in the region farther landwards of the still-water shoreline, the TKE decay rate is very close to that of homogeneous grid turbulence. On the other hand, in the case of a weak bore, the bore collapse generated turbulence is confined near the bottom boundary layer and the TKE decays at a much slower rate.     

ACTA GEOLOGICA SINICA (English Edition) Contents

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Seasonal and spatial characteristics of seawater and sediment at Youngil Bay, southeast coast of Korea

The seasonal geochemical characteristics of the seawater and sediments and the major factors causing heavy metal contamination were investigated at the Youngil bay and the Hyungsan river estuary in the Southeast Coast of Korea, where a world-scale steel-industry complex (Pohang iron and steel industrial complex, POSCO) is located. The seasonal and spatial distribution characteristics of temperature, dissolved oxygen (DO), pH, and nutrients of the seawater were studied at 45 fixed stations, especially focusing on the river mouth area. Sediments at 27 stations were examined during winter and summer to determine the major controlling factors for the distribution of metals, using correlation matrix and R-mode factor analyses, and to evaluate the pollution status, using the modified geoaccumulation (I(geo)(')) index. Temperatures for the effluent from the POSCO located at the Hyungsan river mouth were 2-3 degrees C higher compared to other sampling areas, due to the thermal discharge from the POSCO. The DO concentration of the surface water at the Pohang old port was as low as 2-4 mg/L. In spring, the DO value at the Hyungsan river mouth was higher than 12 mg/L, by the mass multiplication of phytoplanktons at the river mouth where seawater temperature and nutrients concentrations were relatively high, resulting in the pH value of higher than 8.3. The nitrogen to phosphorus (N/P) ratios at the river mouth were 20-150 times higher compared to other areas, implying that the nitrogen loading into this semi-enclosed bay is significantly higher than phosphorus and the major nitrogen sources are not only the domestic sewage from the city but the industrial wastewater from the POSCO and other steel factories nearby. The phosphorus concentrations at the Pohang old port were shown 3-10 times higher than those at other stations, due to the inflow of pollutants generated from the nearby ships anchoring and the release of phosphate from the bottom sediment. Results from the sediment analysis showed that the major controlling factors for the distribution pattern of each metal are grain size and organic carbon (C(org)) content. Based on the factor analysis, Al, Fe, Cr, Li, and Pb were shown strongly correlated with the mean grain size (Mz), whereas Cd, Cu, Zn, and Sn with the C(org) content. Results from the fractionation of the sedimentary metals into lattice and labile fractions to characterize the mobility of sediment metals showed that the mineral lattice fraction was high in the order of Al=K>Cr>Li>Sr>Fe, while the labile fraction, which might be released to the overlying water, was in the order of Pb>Zn>Cd>Cu>Ca>Sn. Evaluation of the sediment pollution status by applying (I(geo)(')) of 13 metals showed Cd, Cu, and Zn as high as 1-3 range at the old port. Even though the overall marine pollution mainly by the world-class steel industrial complex in this semi-enclosed bay area studied does not currently pose a serious threat, due to the seawater circulation and the large influx of river discharge, the countermeasures to implement the sediments concentrated with heavy metals, especially at the old port with no seawater circulation, are still warranted for this coastal water environment.