Spatial scale variability in shoot density and epiphytic leaves of Posidonia oceanica on Kerkennah Island (Tunisia) in relation to current tide effects

A study was undertaken of the patterns of spatial variability, epiphytic biomass and distribution of epiphytic fauna and flora of Posidonia oceanica. Samples were taken at four stations located approximately 4 km apart, exposed to different current conditions. Stations A and B, situated near the Oued Mimoun tidal channel with its relatively strong bi‐directional flows, were affected by high current tide. The other two stations, North Oued Mimoun (L1) and South Oued Mimoun (L2), were located further from the channel, in low current tide conditions. Sampling was conducted in the Attaya area of Kerkennah Island (Tunisia) in August 2009 at depths between 2 and 3 m, with the results indicating differences among the stations. Shoot density decreased when exposed to high levels of hydrodynamic activity generated by current tides whereas the epiphytic biomass of P. oceanica leaves decreased at sheltered stations located far from the channel. Epiphytic algae such as Heterokontophyta, Rhodophyta and Chlorophyta, and epiphytic fauna represented by Bryozoa, Hydrozoa, Annelida, Porifera and Tunicata, dominated the epiphytic assemblages and were abundant at the station most exposed to high current tide hydrodynamics. Cyanobacteria, however, were dominant in stations exposed to low current tide.     

Geochemical Anomaly and Mineral Prospectivity Mapping for Vein-Type Copper Mineralization,Kuhsiah-e-Urmak Area,Iran: Application of Sequential Gaussian Simulation and Multivariate Regression Analysis

Natural Resources Research - In this paper, sequential Gaussian simulation (SGS) and number–size (N–S) fractal modeling were used for copper geochemical anomaly mapping in the western...     

Use of Late-Barremian sands from Central Tunisia in white cement clinker

The present work focuses on the ability of Late-Barremian sands from Ouaddada Mountain (Central Tunisia), to produce high-quality white cement clinker. Results indicate that these sands are particularly characterized by their fineness of grains (mean grain-size 90–140 μm), high cleanness (sand equivalent 88–98%), extremely low coloring oxides and volatiles levels (less than 0.03 and 1.9% respectively) and high values of whiteness and lightness indices (more than 86 and 90% respectively). Studies based on Bogue calculation, X-ray diffraction (XRD), burnability of raw mixes, Point Counting and Scanning Electron Microscopy (SEM) with Energy-Dispersive X-Ray Spectroscopy (EDS) methods, reveal that the Late-Barremian sands from Ouaddada Mountain can be used in the production of white Portland clinker by mixing with 70.8–75.6% of local limestones and 3.5–24.8% by weight of common Mediterranean kaolins from Guadalajar province (Central Spain), Tamazert (North-East Algeria), ?ile (North-West Turkey), Sebha (South-West Libya), and Abu Zanima area (West-Central Sinai, Egypt). Synthesized clinkers are composed largely of alite (75–76.2%), belite (12.8–16.5%) and aluminate (7.4–8.9%) with subordinate quantities of ferrite (less than 1%), slightly harder to burn and seem to be much whiter than Mediterranean ones with a whiteness index β more than 86%.     

Fluctuating asymmetry in grass goby Zosterisessor ophiocephalus Pallas, 1811 inhabiting polluted and unpolluted area in Tunisia

Fluctuating asymmetry, a random deviation of bilateral traits, is assessed on grass goby Zosterisessor ophiocephalus Pallas, 1811 living in one disturbed site and in one unpolluted site Gulf of Gabes (Tunisia). Statistical analysis showed that assessed asymmetries are fluctuating. FA of orbital diameter, sub-orbital distance, pectoral fin and post-orbital length are higher in polluted site compared to control. Chemical pollution seems to be responsible for this high FA.     

Origin and Petrogenetic Implications of Spessartine Garnet in Highly‐Fractionated Granite from the Central Eastern Desert of Egypt

A highly-fractionated garnet-bearing muscovite granite represents the marginal granitic facies of the Abu-Diab multiphase pluton in the Central Eastern Desert of Egypt. New electron microprobe analyses(EMPA) and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) data from garnets are reported, in order to constrain their origin and genesis. Garnet in the Abu-Diab host granite is euhedral to subhedral, generally homogeneous and, in rare cases, it shows weak zonation. The garne...     

Continuum large cracking in a rate‐dependent plastic–damage model for cyclic‐loaded concrete structures

Formulation and algorithmic treatment of a rate‐dependent plastic–damage model modified to capture large tensile cracking in cyclic‐loaded concrete structures are presented in detail for a three‐dimensional implementation. The plastic–damage model proposed by Lee and Fenves in 1998 was founded based on isotropic damaged elasticity in combination with isotropic multi‐hardening plasticity to simulate cracking and crushing of concrete under cyclic or dynamic loadings. In order that the model can capture large crack opening displacements, which are inevitable in plain concrete structures, the excessive increase in plastic strain causing unrealistic results in cyclic behaviors is prevented when the tensile plastic–damage variable controlling the evolution of tensile damage is larger than a critical value. In such a condition, the crack opening/closing mechanism becomes similar to discrete cracking. The consistent tangent operator required to accelerate convergence rate is also formulated for the large cracking state including viscoplasticity. The validation and performance of the modified algorithm implemented in a special finite element program is exemplified through several single‐element tests as well as three structural applications. The last example examines the model in the seismic fracture analysis of Koyna dam as a benchmark problem and the resulting crack profile is compared with the available experiment. The numerical experimentations well demonstrate that the developed model whose modification is necessary to properly simulate the cyclic behavior of plain concrete subjected to large tensile strains is robust and reasonably accurate. Copyright © 2012 John Wiley & Sons, Ltd.     

Spatial diversity of rocky midlittoral macro-invertebrates associated with the endangered species Patella ferruginea (Mollusca: Gastropoda) of Tunisian coastline

The present study focuses on horizontal spatial variability of benthic macrofauna associated with Patella ferruginea. Thirty-six samples collected at 12 transects belonging to 4 midlittoral sites along the rocky Tunisian coastline, were examined. A total of 44 species belonging to 5 taxa were found. Multivariate analysis applied on gathered data did not show a horizontal spatial variability at small scale (between transects), but at large scale, between sites as well as sectors. Thus, three groups of communities were identified (GI: Korbous and El Haouaria; GIIa: Zembra Island and GIIb: Kelibia). The distribution of species abundance within these groups revealed that crustaceans were the most abundant taxon, due to the overwhelming dominance of Chthamalus stellatus. This substratum appeared to create favourable micro-habitats for the installation of molluscs including gastropods. Regarding the low diversity index (H') and evenness (J), they seemed to reflect a disturbance and a demographic unbalance within these communities. The heterogeneity of substrate surface, created by C. stellatus specimens appeared to be caused by various complex interactions established between the key components of these communities in particular suspension feeders, predators, herbivorous molluscs and macroalgae. Thus, the dynamic status of each of these communities is the result of these complex interactions.     

Three-Dimensional Simulation of Water Circulation in the Java Sea: Influence of Wind Waves on Surface and Bottom Stresses

A one-year simulation of tide- andwind-driven circulation in the Java Sea, which is one ofthe Indonesian seas located in a tropical area, hasbeen carried out using a three-dimensionalhydrodynamic model incorporating the influence of thewind waves generated at the sea surface. This area isinfluenced by the monsoon climate (east- andwest-monsoon). Six hourly-wind fields at 10 m abovethe sea surface were used as a representative windfield. In other respects, the effect of waves on thethree-dimensional hydrodynamic model has beenrepresented by the surface and bottom stresses. Athird-generation wave model called WAM (WAMDI, 1988)was used to calculate the wave parameters and thewave dependence of the drag coefficient. Thetrajectory of water particles induced by thecalculated velocity fields in the Java Sea was then simulated.In dealing with hazardous phenomena, this modelwill be extended to predict suspended sediment fluxes,particularly those relating to catastrophic changes in seabottom topography and beach erosion. It is also animportant tool for the prediction of storm surge events.     

Impacts of an uncontrolled phosphogypsum dumpsite on summer distribution of phytoplankton, copepods and ciliates in relation to abiotic variables along the near-shore of the southwestern Mediterranean coast

In connection with the Taparura Project, studies of spatial distribution of the crustacean zooplankton community, nutrients, phytoplankton and ciliates were conducted in July 2007 at 45 stations spread over fifteen transects along the coast north of Sfax. The results showed that the N/P ratio was lower than the Redfield ratio, suggesting potential N limitation. Phytoplankton was characterised by the proliferation of several diatoms, while ciliates were largely dominated by spirotrichs. Copepods were the most abundant zooplankton present during the entire study period, comprising 61% of the total zooplankton community. Twelve copepod families were identified at every station, with a high percentage of Oithonidae (77% of copepods) dominated by Oithona nana. The abundance of this species was correlated with that of diatoms, Cocoolithophorideae and ciliated Colpodea, suggesting that O. nana may feed on a wide range of prey. Despite human pressure and industrial activities, the coastal waters north of Sfax showed a wide diversity of phytoplankton, ciliates and zooplankton.     

Contributions of gravity and field data on the structural scheme updating of the Tellian domain and its foreland (Nefza-Bizerte region,northern Tunisia)

International Journal of Earth Sciences - The Nefza-Bizerte region, eastern part of the Tunisian Alpine chain, covers the thrust sheets domain called the Tell and its Atlassic foreland. The deep...