Zonation Structure Research Articles

A possible archaic precursor of the octocoral structural plan from the Ordovician of Estonia

AbstractA new species and genus of colonial coral, Lindaphylon solovjevi, from the Upper Ordovician of Estonia is described in detail. The colony has a zonation similar to the zonation structure of the mesogleal skeleton of octocorals, since it consists of a narrow axis and a surrounding wide cortex of small calcite sclerites and a system of large solenia. Corallites present 12 sclerosepta in a wide shallow cup. A new family Lindaphylonidae and an order Lyndaphylonaceae are based on these features, and a new order placed in the subphylum Anthozoa as incertae sedis. A comparative study of skeleton formation and mesenteric apparatus symmetry in different groups of coral polyps is considered in detail.

Mouse Cyp2c expression and zonation structure in the liver begins in the early neonatal stage.

In the adult liver, drug-metabolizing enzymes such as cytochrome P450 (CYP) efficiently metabolize drugs by forming an expression pattern called "zonation" structure around the central veins (CV). However, most previous studies on CYPs have focused on the expression levels of CYP mRNA and proteins in the whole liver. In this study, we analyzed not only the expression levels of Cyp2c family mRNAs and proteins in mice during fetal liver development, but also the relationship with their localization. In the whole fetal liver, Cyp2c mRNA and protein were hardly expressed. On the other hand, zonation analysis results showed that only some cells around the CV of the fetal liver expressed Cyp2c. In addition, the protein expression level of Cyp2c in the whole liver during the neonatal period started from postnatal day (P) 7 in both males and females, while the zonation was weakly formed from P5. This study suggested that fetal liver cannot metabolize Cyp2c substrate drugs transferred from mother to fetus due to the low expression of Cyp2c and unformed zonation. The expression level of Cyp2c protein in neonates was lower than that in adult liver, and the zonation structure was not clear, suggesting that drug metabolism was not sufficient. Furthermore, this study revealed that the expression level of Cyp2c does not correlate with the formation of zonation structures, because Cyp2c expression is found in hepatocytes near the CV even in the fetal and neonatal stages, when Cyp2c protein expression is hardly detectable in the whole liver.

Identifying arbitrary parameter zonation using multiple level set functions

In this paper, we extended the analytical level set method [1,2] for identifying a piece-wisely heterogeneous (zonation) binary system to the case with an arbitrary number of materials with unknown material properties. In the developed level set approach, starting from an initial guess, the material interfaces are propagated through iterations such that the residuals between the simulated and observed state variables (hydraulic head) is minimized. We derived an expression for the propagation velocity of the interface between any two materials, which is related to the permeability contrast between the materials on two sides of the interface, the sensitivity of the head to permeability, and the head residual. We also formulated an expression for updating the permeability of all materials, which is consistent with the steepest descent of the objective function. The developed approach has been demonstrated through many examples, ranging from totally synthetic cases to a case where the flow conditions are representative of a groundwater contaminant site at the Los Alamos National Laboratory. These examples indicate that the level set method can successfully identify zonation structures, even if the number of materials in the model domain is not exactly known in advance. Although the evolution of the material zonation depends on the initial guess field, inverse modeling runs starting with different initial guesses fields may converge to the similar final zonation structure. These examples also suggest that identifying interfaces of spatially distributed heterogeneities is more important than estimating their permeability values.

An analytical approach for the simulation of flow in a heterogeneous confined aquifer with a parameter zonation structure

AbstractThis study introduces an analytical approach to estimate drawdown induced by well extraction in a heterogeneous confined aquifer with an irregular outer boundary. The aquifer domain is divided into a number of zones according to the zonation method for representing the spatial distribution of a hydraulic parameter field. The lateral boundary of the aquifer can be considered under the Dirichlet, Neumann or Robin condition at different parts of the boundary. Flow across the interface between two zones satisfies the continuities of drawdown and flux. Source points, each of which has an unknown volumetric rate representing the boundary effect on the drawdown, are allocated around the boundary of each zone. The solution of drawdown in each zone is expressed as a series in terms of the Theis equation with unknown volumetric rates from the source points. The rates are then determined based on the aquifer boundary conditions and the continuity requirements. The estimated aquifer drawdown by the present approach agrees well with a finite element solution developed based on the Mathematica function NDSolve. As compared with the existing numerical approaches, the present approach has a merit of directly computing the drawdown at any given location and time and therefore takes much less computing time to obtain the required results in engineering applications.

페루 남동부 아뿌리막주 트라피체 동-몰리브데늄 광상의 지질 및 광화작용

Trapiche project corresponds to the advanced exploration stage which is thought to be a part of various porphyry copper deposits occurring in the margin of Andahuyalas-Yauri metallogenic belt. This deposit is genetically related to the monzonitic porphyry intrusion and Oligocene breccia pipe. Mineralization consists of primary sulfides such as pyrite, chalcopyrite, bornite, and molybdenite and secondary sulfides such as chalcocite, covellite and digenite. It occurs malachite, tenorite and cuprite as copper oxide. As a result of lixiviation or enrichment process, mineralization shows untypical zonation structure. Breccia and porphyry areas characterize the vertical zonation patterns. In the northern area, lixiviation zone, secondary enrichment zone, transitional zone and primary mineralized zone are distributed in northern area. In the western area of deposit, oxidation zone and mixed zones are narrowly occurred. Inferred resources of deposit is estimated to be 920 Mt @ 0.41% Cu with the cut-off grade of 0.15%.

Effects of shoreline erosion on salt-marsh floral zonation

The loss of salt-marsh habitat is proceeding at an alarming rate worldwide, resulting in the loss of ecosystem function and reduced exchange with adjacent habitats. The immediate result of shoreline erosion is the loss of fringing vegetation, but it is unclear how, and at what temporal scale, intertidal floral zones respond to shoreline loss. Using a transect-based approach over a 3 yr period, we compared community composition among 3 intertidal salt marshes in coastal Alabama that differ in the intensity of wave-generated disturbance. Each study marsh exhibited net annual rates of shoreline retreat, but differed in its exposure to wave-induced disturbance and erosional state. We also examined whether wave attenuation by oyster break waters reduced annual rates of shoreline erosion, providing a means to test whether the intensity of shoreline erosion affects inter-annual patterns of marsh zonation. Community composition differed across sites, but not between breakwater treatments and site-specific rates of shoreline loss, suggesting that differences in community composition are not due to differences in erosion intensity, but to other contrasts across sites. The cohesive nature of the floral communities at each site suggests that marshes maintain their zonation structure by migrating inland as the shoreline recedes. The inland migration of marsh zones will, however, ultimately be limited by the lack of area available for marsh colonization. The preservation of coastal salt marshes is, therefore, vitally contingent on effective shoreline management strategies.

Zoning for management in wetland nature reserves: a case study using Wuliangsuhai Nature Reserve, China

BackgroundZoning is a fundamental tool for the effective management of nature reserves. A three-zone model (core zone, buffer zone, and experimental zone) has been applied to nature reserves in China since 1980s; however, this model appears not fit for all types of nature reserves, especially wetlands.Case descriptionWuliangsuhai is such a typical wetland reserve, which can represent most of the other wetland reserves in China, for both its human utilization, and for its function as the bird habitat. The “Component-Process-Service” (CPS) framework of the Convention on Wetlands allows a determination of the “ecological character” of the wetland and also allows identification of potential threats, providing thus a perspective for management opportunities and challenges.Discussion and evaluationApplying the CPS framework to Wuliangsuhai wetland nature reserve, we have had a better understanding of the ecosystem services and its relationship with the ecological process and components of the wetland. A comparison of effectiveness in maintaining ecosystem services by the two zoning models (the existing three-zone model, and the new zoning model) was made.ConclusionsThe study suggested introducing an additional risk-control zone to be more effective in managing and alleviating threats to the ecological character than the standard 3-zone system. Furthermore, a “dynamic” zoning that takes into account the annual variation in habitat and avifauna distribution, as an elaboration of the Four-zone structure, may achieve the desired conservation objectives in an even more effective manner. The proposed zonation structure has the added benefit of promoting harmonization between nature conservation and local sustainable development.

Diversity and abundance of wrasse species in the Gulf of Aqaba

The diversity, distribution and abundance of wrasse fishes of the family Labridae were analysed along the Egyptian Red Sea coast in the southern Gulf of Aqaba. Different sites around Dahab (South Sinai Peninsula) were investigated at 4 depth levels from reef flat to reef slope and fore reef. A total of 37 species from 19 genera were recorded, and evenness and diversity indices, frequency, absolute and relative abundances of the species were calculated. A total of 10 more species were observed outside sampled transects resulting in a total diversity of 47 wrasse species for the region. The Gulf of Aqaba thus harbours a higher wrasse species richness than previously reported. The spatial heterogeneity of wrasses was influenced by the reef zonation, substrate composition and habitat structure. The average number of species was highest on the reef slope, while wrasse density was highest on the reef flat due to the schooling of some smaller species and aggregations of juveniles. Many wrasse species showed a clear zonation preference in their distribution and occurred in limited habitats, while others were documented in all areas and depth levels. Environmental influences have a major impact on the species composition in coral reefs. Some factors were evaluated for their importance on the wrasse diversity in the Gulf of Aqaba. Temperature and photoperiod-dependent reproductive cycles have been identified for most species. All studied reefs showed high wrasse diversity, which was (among other factors) influenced by tourist activities (e.g. SCUBA diving) in the area.

Role of post-settlement mortality in the establishment of Acropora reef slope zonation in Ishigaki Island, Japan

The relative contributions of larval recruitment and post-settlement mortality to the establishment of the zonation of Acropora communities, a dominant group in reef corals, remain unknown. Our field research revealed that the relative abundances of juveniles between two morphological categories of acroporid corals were different on shallow and deep slopes: tabular species dominated in shallow waters (1.5-2.5m), whereas arborescent species dominated in deep waters (5.5-11m). These abundances were consistent with the distributional patterns of the adults, suggesting that the zonation structure is formed during the initial life stages of settlement and early post-settlement periods. To determine to what extent Acropora zonation is determined by depth-related differences in initial mortality among species, a transplant experiment using artificially settled corals (10 days after settlement) of four dominant species (the shallow-dominants Acropora digitifera and A. selago and the deep-dominants A. muricata and A. tenuis) was performed at four depths (1.5, 2.5, 5.5, and 11m). Survivorship of all four species was lower at 5.5m than the other depths and that the survival rate of A. muricata was much higher than that of other species at all depths. However, there was no species-specific survival related to adaptation to a particular habitat (i.e., depth), implying that Acropora spats do not possess species-specific tolerance for the environmental stresses of their own particular habitat, at least during the first 6 months after settlement. Post-settlement survival rate during this period is therefore not a major factor in forming the vertical zonation pattern of these Acropora species in subtropical reefs around Japan.

Enhancing random heterogeneity representation by mixing the kriging method with the zonation structure

This research develops a zonation‐kriging (ZK) method and extends the geostatistical theory to investigate the spatially distributed random field and obtain an optimal nonsmooth conditional estimate. In the ZK method the zonal structure honors the parameter measurements such that each sample location represents a distinct zone, while the kriging method also honors the same data set and results in a smooth distribution. The ZK method integrates the conditional estimates of the zonal structure and the kriged field over a set of weighting coefficients on the sample data. The extended geostatistical theory using the ZK method is applied to the intrinsic field, stationary field, and nonstationary field. The study shows that the conditional variance using the ZK method is bounded between the kriging variance and variogram. When estimating hydraulic conductivity by inversion of a groundwater model, the optimal values of weighting coefficients are determined via predictive probability of the Bayesian decision theory. The numerical examples show that the ZK method has less dependence on the semivariogram model. The ZK method outperforms the kriging method in both smooth and nonsmooth fields. The ZK method shows high efficiency to better the conditional estimate of hydraulic conductivity distribution with low conditional uncertainty and good agreement to the groundwater head observations.

Characterization and identification of aquifer heterogeneity with generalized parameterization and Bayesian estimation

This research proposes a generalized parameterization method (referred to as GP) and Bayesian estimation for parameter heterogeneity characterization and identification in groundwater modeling. GP unifies zonation and interpolation through a set of weighting coefficients and is capable of creating a zonation structure, a continuous distribution, or a mixed structure. GP shows greater flexibility not only in manipulating the highly complex spatial distribution but also in identifying the parameter structure. With GP, parameter structure identification seeks to identify the parameter dimension, parameter pattern, parameter values, as well as the values of the weighting coefficients simultaneously through a set of basis points. Additionally, this study develops an embedded genetic algorithm (GA) for solving the structure identification problem. A Bayesian estimator that estimates the basis point values as well as the values of the weighing coefficients is embedded in the GA, which searches for the best basis point locations. We demonstrate the inverse methodology by a numerical example in which the distributed transmissivity in a two‐dimensional confined aquifer is identified. We calculate the Jacobian matrix by the adjoint state method. With GP we have successfully identified the transmissivity structure with four basis points that results in a good fitting in groundwater heads and captures the nonsmooth characteristic as well as the trend of the true transmissivity field. We compare GP with Voronoi tessellation (zonation) and natural neighbor interpolation. Results show that GP outperforms the other two parameterization methods in that GP identified the transmissivity field with a smaller parameter uncertainty along with a sufficiently small fitting residual and without over‐parameterization.

Local changes in the composition and community structure of suprabenthic peracarid crustaceans on the bathyal Mediterranean: influence of environmental factors

Deep-water assemblages of suprabenthic peracarids were analyzed in the SW Balearic Islands (Algerian Basin, southwestern Mediterranean) between 249 and 1,622 m depth; the patterns of species composition, possible zonation, and trophic structure found in this area were compared with those exhibited by peracarids in the mainland side of the Catalan Sea slope (northwestern Mediterranean). One hundred and four peracarid species (plus one leptostracan) were identified on the Balearic Islands slope, amphipods being the most diversified taxon (45 species). On the Balearic slope, two distinct depth assemblages were distinguished: one at the upper slope (US), between 249 and 402 m depth and the second at the deep slope, between 543 and 1,620 m depth. A remarkable species substitution occurred at depths between 402 and 638 m. In the Catalan Sea, in addition to the US assemblage occupying depths between 208 and 408 m, a second boundary of faunal change was found around 1,250 m. Suprabenthos biomass increased from 242 to approximately 500 m. Suprabenthos attained the highest biomass values (100 g wet weight/10,000 m2) at intermediate depths between 504 and 1,211 m, as also occurred with the associated zooplankton collected with suprabenthos (peak biomass between 502 m and 898 m). Suprabenthos biomass did not show any significant correlation with any environmental water-column variable. In contrast, zooplankton (especially small fish and decapod crustaceans) showed a significant positive correlation with fluorometry and turbidity at different levels of the water column. The feeding guilds of species showed important differences between the two areas only on the US, with a higher abundance of deposit feeders in the Catalan Sea (20.4%) than in the Balearic Islands (4.2%). The low contribution of deposit feeders in the SW Balearic Islands may ultimately be a consequence of the lack of river discharges in this area.

Simultaneous Estimation of Transmissivity Values and Zonation

The extended Kalman filter (EKF) has long been recognized as a powerful, yet computationally intensive, methodology for stochastic parameter estimation. Three improvements to traditional algorithms are presented and applied to heterogeneous transmissivity estimation. First, the costly EKF covariance updates are replaced by more efficient approximations. Second, the zonation structure of the distributed parameter field being estimated is dynamically determined and refined using a partitional clustering algorithm. Third, a new method of merging first and second moments of random fields that have heterogeneous statistics is introduced. We apply this method, called random field union, as an alternative to conventional random field averaging for the systematic shrinking of covariance matrices as the dimensionality of the parameter space is reduced. The effects of these three improvements are examined. In applications to steady state groundwater flow test problems, we show that the first and second improvements reduce the computational time requirements dramatically, while the second and third can improve the accuracy and stability of the results. The resulting integrated method is successfully applied to a larger, more realistic calibration test case under steady and cyclostationary flow conditions (similar to regular seasonal fluctuations). When flow is steady, the method can be viewed as iterative; when flow is transient, the method is fully recursive.

Determination of the transmissivity zonation using a linear functional strategy

For aquifers having a zonation structure with the transmissivity varying smoothly and slowly over each zone, a common approach in determining transmissivity is to presume a known zonation structure and seek a constant approximation to the transmissivity over each zone. However, this procedure is not always acceptable as it may lead to instability in the estimation process. By adapting the linear functional strategy proposed by Anderssen and Dietrich (1987), the authors show how one may simultaneously determine the zonation structure and a piecewise constant representation of the transmissivity. Stability results are derived for this procedure under conditions which guarantee identifiability. A generalization of this method using a Petrov-Galerkin interpretation is also examined.