Variable Topography Research Articles

The influence of static versus dynamic pressure distribution strategies for modelling nonlinear waves generated by ships

A moving static pressure distribution is commonly used to simulate a travelling ship. However, the ship movement changes the fluid velocity around the hull, inducing pressures on the hull surface that are no longer equal to the static pressure. Therefore, we introduce a dynamic pressure correction strategy, which can accurately simulate the impact of the ship movement on the hull-surface pressure and preserve the desired hull shape under both stationary and transient conditions. The strategy is applied to a high-order spectral model and used to investigate ship-induced waves and wave resistance over a both flat and variable topography. We explore various parameters in our study, including the average water depth to ship draft ratio ( $h_0/d$ ), the channel width to ship width ratio ( $W/B$ ), the Froude number ( $Fr_0=U/\sqrt {gh_0}$ ) and variations in bathymetric slope. Compared with experiments on a flat bottom, the numerical results with dynamic correction show better accuracy in the simulation of ship-induced waves and wave resistance than those obtained using a static pressure distribution. The correlation coefficient for wake waves between the numerical and experimental results is improved by approximately 0.25 with the dynamic correction strategy. The amplitude and wavelength of ship-induced mini-tsunamis over a variable topography are found to be reduced when employing a dynamic correction compared with a static pressure distribution, and this effect becomes more pronounced with higher Froude number. The static pressure approach is shown to allow large deformations of the desired hull shape and changes in ship volume which are responsible for the different wave patterns from the two approaches.

Exploring the Branching Pattern of the Posterior Division of the Internal Iliac Artery: An Analysis Based on 75 Computed Tomography Angiographies.

The internal iliac artery stands as the main blood supplier of the pelvis, serving as the primary source of blood for the pelvic viscera while also nourishing the musculoskeletal framework within. The arterial anatomy of the pelvis exhibits a vast array of variations, especially regarding the branching pattern of the internal iliac arteries. The posterior division of the internal iliac artery (PDIIA) may also have variable topography, especially regarding the location of its origin in the pelvic region. A retrospective study was carried out to determine the anatomical variations, prevalence, and morphometric data of the PDIIA and its branches. A total of 75 computed tomography angiographies were analyzed. The most prevalent branch of the PDIIA was the superior gluteal artery, as it was present in 114 of the studied cases (77.03%). The median diameter of the PDIIA at its origin was 6.66mm. The median cross-sectional area of the PDIIA at its origin was set to be 34.59 mm2. Our study highlights the critical significance of understanding the PDIIA and its branches in surgical interventions aimed at managing pelvic hemorrhage. The present study provides valuable insights into the precise localization and characteristics of the PDIIA and its branches, which are essential for surgical procedures targeting specific vessels to control bleeding effectively. Owing to the high level of variability of the branching pattern of the PDIIA, a novel classification system consisting of six types was created.

Size and Topography of the Brain’s Functional Networks with Psychotic Experiences, Schizophrenia, and Bipolar Disorder

BackgroundExisting functional connectivity studies of psychosis use population-averaged functional network maps, despite highly variable topographies of these networks across the brain surface. We aimed to define the functional network areas and topographies in the general population and the changes associated with psychotic experiences (PEs) and disorders. MethodsMaps of 8 functional networks were generated using an individual-specific template-matching procedure for each participant from the Human Connectome Project Young Adult cohort (n = 1003) and from a matched case cohort (schizophrenia [SCZ], n = 27; bipolar disorder, n = 35) scanned identically with the same Connectom scanner. In the Human Connectome Project Young Adult cohort, PEs were estimated based on scores from the Achenbach Self-Report Scale. The relationship of symptoms to the probability of network representation at each cortical vertex was assessed using logistic regression. ResultsIn Human Connectome Project Young Adult participants, PE severity on the Achenbach thought problems scale was predicted by increased language network (LAN) and dorsal attention network (DAN) areas and decreased cingulo-opercular network area (r < 0.12). Significant effects were found in SCZ, with a larger DAN and LAN and a smaller frontoparietal network. Network pattern analysis in SCZ showed an increased probability of LAN in the posterior region of the left superior temporal gyrus and of the visual network in the left insula. Regression analyses in SCZ found that mood dysregulation was related to increased DAN surface area. ConclusionsThose with PEs and SCZ showed abnormal functional network cortical topographies, particularly involving DAN and LAN. Network findings may predict psychosis progression and guide earlier intervention.

Rock outcrops as interglacial refugia for plants: Ecological evidence from the forest‐steppe transition of Patagonia

AbstractIn the forest‐steppe transition of Patagonia from Argentina, the intense physical variability promotes the occurrence of contrasting vegetation units, among which is the saxicolous meadow developed on rock outcrops. In temperate and tropical regions, these geoforms of highly variable climate and topography, and poor soil development play an ecological and evolutionary role disproportionate to their reduced area. In Aguas Frías (38°46′S, 70°54′W), the range, diversity, density and adaptation of vascular plant species growing in the saxicolous meadow were compared to those of the surrounding steppe, forest and hygrophilous meadow. We hypothesize that rock outcrops exhibit a compositionally and functionally divergent, cold‐adapted flora of a previously more widespread distribution, allowing them to be categorized as refugia for species whose range retreated during the current interglacial. In comparison to the other units, the saxicolous meadow exhibited a small area, low plant cover, high total, native and rare species richness, high density and diversity of species, high richness of unique families and species and an exclusive presence of (rock) ferns. It also presented a high richness of endemic species with more extreme latitudinal and altitudinal distribution, particularly &gt;46° S and &gt;3000 m a.s.l. The similarity of species between the saxicolous meadow and the other units was low. Chamaephytes and nanophanerophytes were dominants, hemicryptophytes and geophytes were infrequent and mesophanerophytes and therophytes were absent. Equivalent results in terms of area of rock outcrops, and origin, strategy, composition, diversity and range of species were found in different regions. The biological and physical attributes would allow these outcrops to be characterized as reduced habitats of high diversity which could be acting as refugia for cold‐adapted plants. Conservation actions must prevent and mitigate the effects of fire, biological invasion and cattle grazing that represent the current threats to this ecosystem.

Variability of the Bottom Boundary Layer Induced by the Dynamics of the Cross‐Isobath Transport Over a Variable Shelf

AbstractThe bottom boundary layer (BBL) dynamics play an important role in regulating the energy, momentum balance, and circulation in the shallow shelf areas. Unlike previous studies that disconnected BBL with background variable shelf circulation, we investigate the dynamic connection between the wind‐driven shelf circulation and BBL dynamics, and show the spatial characteristics of BBL dynamics in response to three‐dimensional (3D) heterogeneous transport over the highly variable shelf topography in the Northern South China Sea. Our process‐oriented modeling study demonstrates that the mixing dynamics and upslope buoyancy transport over varying shelf topography alter the spatial variability of BBL dynamics. Driven by southwesterly upwelling‐favorable winds, the along‐shelf current generated a frictional upslope Ekman transport. The along‐isobath pressure gradient force () formed by the flow‐topography interactions over the meandering shelf induces the geostrophic cross‐isobath transport. The downwave (upwave) enhances (offset) the frictional upslope transport over the east (west) of the shelf that has a concaving (uniform) bottom topography. Over the eastern shelf with concave isobaths, the intensified and upslope cross‐isobath dense water transport strengthen stratification and weaken the effect of bottom stress‐induced mixing, limiting the development of the BBL. The antithesis occurs over the western shelf, where a small bottom stress controls the BBL. River discharge and the tidal current modulate the alongshore current, upslope transport, bottom stress intensity, and BBL development. We model the trajectory of seabed particles as they respond to the BBL dynamic regimes, and find that high (low) concentration, short (long) suspension time, and strong (weak) shoreward transport occurover the eastern (western) shelf, respectively.

3D Genial Tubercle Anatomic Considerations in Genioglossus Advancement Surgery.

To qualitatively describe variation in morphology of the genial tubercle and quantify the spatial relationship between the tubercle and genioglossus muscle. Case series. Cadaver dissection. Segmental sections of the mandible, with muscular attachments intact, were harvested from 18 fresh cadaver heads. Three-dimensional laser scans, with a resolution of 0.025 mm, were taken of each specimen with muscle attached and repeated after muscle removal. The genioglossus muscular attachment was measured relation to bony landmarks. The morphology of the genial tubercle varied, with anywhere from 1 large spine to 4 individual spines. However, all specimens had a distinguishable superior portion of the tubercle, where the genioglossus attached, and an inferior portion, where the geniohyoid attached. The height of the superior tubercle (ST) was 6.1 mm (95% confidence inerval [CI]: 5.7-6.5). The height of the genioglossus muscle above the peak amplitude of the ST was 4.3 mm (3.8-4.9), but only 2.5 mm (2.0-3.0) below. On average, 64.4% (58.6-70.2) of the height of the genioglossus muscle attachment was above the peak. Overall, 19.5% (14.1-25.0) of the muscle surface area extended beyond the boundaries of the tubercle. The genioglossus muscle attachment originates from the superior genial tubercle, which has a variable topography and amplitude. However, the muscle is not centered on the spines-more of the muscular fibers attach above the spine as compared to below. This new data may explain the genioglossus advancement "miss rate"-failure to advance muscle on initial osteotomy-of 39-78% reported in the literature.

Intraocular lens selection in diabetic patients: How to increase the odds for success.

The incidence of cataracts is significantly higher in diabetic individuals, particularly in younger age groups, with rates quadrupled in those under 65 and doubled in those over 65 compared to non-diabetics. Cataract surgery in diabetic patients poses many challenges: Poor epithelial healing, decreased corneal sensitivity, increased central corneal thickness, decreased endothelial cell count, variable topography, poor pupillary dilatation, anterior capsular phimosis, posterior capsular opacification (PCO), chances of progression of diabetic retinopathy (DR), zonular weakness, and vitreous prolapse and diabetic macular edema. Selection of an appropriate intraocular lens (IOL) is crucial for visual rehabilitation and monitoring DR. The choice of IOL in diabetic cataract patients is a challenging scenario. Square-edge IOLs are favored for their capacity to mitigate PCO, whereas hydrophilic counterparts may incur calcification in the setting of proliferative DR. The advisability of premium IOLs for achieving spectacle independence warrants judicious evaluation, particularly in the presence of advanced retinopathy. Optimal IOL placement within the capsular bag is advocated to minimize postoperative complications. Rigorous preoperative assessment and informed patient counseling regarding IOL options are indispensable for optimizing surgical outcomes. This review article covers various aspects regarding the choice of IOLs in different case scenarios and complications in the diabetic population.

An arterial map of the uterine artery - a tool for endovascular and gynecological procedures

IntroductionThe anatomy of the uterine artery (UA) is highly complex, demonstrating various patterns of origin and course. The main objective of the present study is to provide the first anatomical heat map of the UA, demonstrating the location of its origin and course in the pelvis.MethodsIn July 2022, an assessment was conducted on the findings from 40 consecutive female patients who had undergone computed tomography angiography of the abdomen and pelvis. Morphometric features of the UA and its associated anatomical area were gathered in 19 categories.ResultsThe presented results are based on a total of 58 UAs. 40 UAs originated from the anterior trunk of the internal iliac artery (69.0%), 16 of the UAs originated from the umbilical artery (27.6%), and the remaining two originated from the inferior gluteal artery (3.4%). The median diameter of the UA at its origin was found to be 3.20 mm (LQ = 2.63; HQ = 3.89).ConclusionThe anatomy of the UA is highly complex, showcasing variable topography, origin patterns, and morphometric properties. In the present study, a novel arterial map of this vessel was made, highlighting the diversity in its origin location and course. In our studied cohort, the UA originated most commonly from the anterior trunk of the internal iliac artery (69.0%), as described in the major anatomical textbooks. Having adequate knowledge about the anatomy of this artery is of immense importance in various gynecological and endovascular procedures, such as hysterectomies and embolizations.

Incorporating flowpaths as an explicit measure of river-floodplain connectivity to improve estimates of floodplain sediment deposition

Variation in floodplain topography can lead to gradual flooding and increase river-floodplain connectivity. We show that incorporating flowpaths as an explicit measure of river-floodplain connectivity can improve estimates of floodplain sediment deposition. We focus on the floodplain of the South River, downstream of Waynesboro, Virginia, where measurements of mercury accumulation have been used to estimate decadal-scale sedimentation rates. We developed a two-dimensional Hydrologic Engineering Center's River Analysis System (2D HEC-RAS) hydrodynamic model and used simulated model results with sediment deposition data to create regression models describing sedimentation across the floodplain. All of our statistical models incorporated a flowpath length from the location on the floodplain downstream to the riverbank as an explicit measure of river-floodplain connectivity that improved our estimates of floodplain sediment deposition (r2 = 0.514). We applied our best regression model to our hydrodynamic model results to create a map of floodplain sedimentation rate and discuss differences of three separate sections of floodplain. We found that floodplains with variable topography had wider, bimodal probability distribution functions (PDFs) of sedimentation rate (aggregated spatially) than floodplains without this topographic relief (with narrower log-normal PDFs). Our work highlights how floodplain topography and river-floodplain connectivity affect sedimentation rates and can help inform the development of floodplain sediment budgets.

Optimization of Multibeam Survey Measurement Based on Greedy Algorithm

The effectiveness of multibeam bathymetric technology is widely recognized in marine depth measurements, especially in areas with complex and variable seafloor topography. This study aims to design a multibeam bathymetric survey plan for a specific maritime region, with the objectives of minimizing the total survey line length, ensuring comprehensive coverage of the target area, controlling the overlap between adjacent survey lines, and fully considering variations in seafloor topography. An optimization model was developed to determine the optimal route for comprehensive seafloor depth measurements within the specified maritime area.The model initially considers the influence of seafloor slope, establishing a single optimization objective model with the goal of minimizing the total survey line length. The decision variables primarily include the spacing between adjacent survey lines. The objective function of the model aims to reduce the number of survey lines, thereby achieving the minimization of the total survey line length. Constraints of the model encompass limitations on coverage range, calculations of coverage width, and relationships between survey lines. The model is solved using a greedy algorithm-based optimization approach, iteratively updating the positions of survey lines while determining the spacing based on the relationship between depth and coverage width. Ultimately, a layout of survey lines with the shortest total length, totaling 64 nautical miles with a configuration of 32 survey lines, is obtained for the assumed maritime area. Multibeam bathymetric technology holds broad prospects in the field of marine measurements, particularly in areas characterized by complex and variable seafloor topography. This study, by designing a multibeam bathymetric survey plan for a specific maritime region, not only contributes to improving measurement efficiency and accuracy but also reduces measurement costs and resource consumption. The outcomes of this research have significant practical implications for marine resource development, seafloor engineering construction, environmental protection, providing professionals in related fields with an effective measurement method and optimization strategy.

High order well-balanced asymptotic preserving IMEX RKDG schemes for the two-dimensional nonlinear shallow water equations

In this paper, a high order well-balanced asymptotic preserving scheme is presented for the two-dimensional nonlinear shallow water equations over variable bottom topography in all Froude number regimes. To obtain the well-balanced property, the system is first reformulated as a new form by introducing an auxiliary parameter. The flux is then split into a linear stiff part to be treated implicitly and a nonlinear non-stiff part to be treated explicitly, and the source term is treated explicitly. An implicit-explicit Runge-Kutta discontinuous Galerkin scheme is designed for solving the equations. The proposed scheme can be proved to be well-balanced, asymptotic preserving and asymptotically accurate. Finally, several numerical tests are carried out to validate the performance of our proposed scheme.

Gaussian Pulses over Random Topographies for the Linear Euler Equations

This study investigates numerically the interaction between a Gaussian pulse and variable topography using the linear Euler equations. The impact of topography variation on the amplitude and behavior of the wave pulse is examined through numerical simulations and statistical analysis. On one hand, we show that for slowly varying topographies, the incoming pulse almost retains its shape, and little energy is transferred to the small reflected waves. On the other hand, we demonstrate that for rapidly varyingtopographies, the shape of the pulse is destroyed, which is different from previous studies.

Spatio-temporal variations of lacustrine groundwater discharge and related nutrient fluxes in a typical lake in front of hillocks

Lacustrine groundwater discharge (LGD) as a hidden hydrologic process has been widely found to affect water and nutrient balance in various lakes, but a comprehensive research on both spatial and temporal variations of LGD and associated nutrient fluxes was poorly conducted. Herein, this study elucidated their spatio-temporal variations and underlying factors of a typical lake in front of hillocks with spatially variable topography and hydrogeology, and intense seasonal groundwater-lake exchange, within central Yangtze River basin. The 222Rn mass balance model was used in conjunction with hydrochemistry, water isotope, and nutrient data. The results showed that the overall LGD rate and related N/P fluxes were clearly higher in the wet season than in the dry season, for which the stronger evaporation relative to precipitation, more groundwater recharge from agricultural irrigation or aquacultural pond infiltration, and more N/P input from anthropogenic or aquacultural activities could be responsible. In the wet season, the area with more recharge from irrigating water or fish pond water infiltration and associated extensive agricultural or aquacultural activities, had the significantly highest LGD rate and related N/P fluxes. In the dry season, the area with the deepest water depth and largest topographic slope, exhibited the significantly highest LGD rate and slightly higher LGD-related N/P fluxes due to relatively low groundwater N/P concentrations. This study enriched the understanding on LGD and related nutrient fluxes in the perspective of both spatial and temporal variations, taking a new type of lakes (i.e., lakes in the transitional zone of hills and plains in temperate climate) as a typical case.

TOPOGRAPHICAL EFFECTS ON WAVE SCATTERING BY AN ELASTIC PLATE FLOATING ON TWO-LAYER FLUID

This article illustrates the hydroelastic interactions between surface gravity waves and a floating elastic plate in a two-layer liquid with variable bottom topography under the assumptions of small amplitude waves and potential flow theory. In this study, semi-infinite and finite-length plates are considered. The eigenfunction expansion method is applied in the fluid region with uniform bottom topography. A system of differential equations (mild-slope equations) is solved in the fluid region with variable bottom topography. From the matching and jump conditions, the solution is expressed as a linear algebraic system from which all the unknown constants are computed. We explored the effects of density ratio, depth ratio, and bottom topography on the bending moment, shear force, and the deflection of the elastic plate. Results show that when the density ratio becomes closer to one, the occurred bending moment and shear forces to the elastic plates tend to diminish. The bending moment and shear forces to the pates are higher and lower at a smaller depth ratiofor the incident surface wave and interfacial waves, respectively. The variations in the bending moment, shear force, and plate deflection, caused by surface and interfacial waves, are observed to be in opposite trends, respectively. Bottom profiles similarly affect semi-infinite and finite-length plates when they undergo free-edge conditions. These effects, however, are substantial when the plate is simply supported at the edges. Elastic plate with free edges experiences lower deflection for concave-up and plane-sloping bottoms for incident surface and interfacial waves, respectively.

Zone-specific longshore sampling as a strategy to reduce uncertainties of SGD-driven solute fluxes from high-energy beaches

Submarine groundwater discharge (SGD) from intertidal beach systems forms a source of fresh and saline, often nutrient-enriched water to the near-shore across the world. The chemical composition of solute flux via SGD depends on several factors, including solid phase composition, organic matter supply, hydraulic gradients, as well as pore water residence time and origin, which are partly related to the beach topography. High-energy sandy beaches are especially prone to frequent sediment relocation and a variable topography, often characterized by a ridge and runnel structure. Topography may not only change on a temporal scale, but also in the longshore direction, which may alter SGD-driven solute fluxes. However, sampling high-energy beach sites is challenging and often does not allow for high resolution cross- and longshore sampling. We tested the approach of zone-specific pore water sampling, whereby samples were taken at the high water line, in the runnel, on top of the ridge, and close to the low water line of eight cross-shore transects. This was done in order to assess the longshore variability of pore water composition and flux over a 2.5 km wide beach section. In this study we relied on relatively few data points per transect and still found a characteristic cross-shore distribution of pore water parameters, related to redox conditions of each zone. Recharge zones (high water line and ridge) exhibited higher O2 and NOx concentrations and discharge zones (runnel and low water line) exhibited higher nutrient, DOC, Mn, and Fe concentrations. Furthermore, DOC concentrations in pore waters were lower than in coastal seawater, supporting previous assumptions of rapid organic matter turnover. Nevertheless, we observed large concentration ranges among samples assigned to the same zone, which could partly be related to longshore topography differences. The measured pore water concentrations and calculated SGD-driven solute fluxes indicated that sampling of single cross-shore transects may be representative for a beach section when assessing a redox-independent parameter like Si, while it is less representative for parameters affected by more complex biogeochemical processes like P, NH4, Mn, and Fe. For these, we suggest that longshore distributed data coverage combined with higher resolution sampling in discharge zones is a good strategy to reduce the uncertainty associated with estimating SGD-driven solute fluxes in a practicable way.

Synoptic sampling reveals spatial stability in flow and chemistry patterns despite large seasonal variability in a subarctic mountain catchment

AbstractSeasonality plays a critical role in cold mountain regions as variation in air temperature, ground thermal status, and precipitation phase alter the rate, timing and magnitude of hydrological and chemical transport. Additionally, cold mountain catchments can have highly variable topography, geology, permafrost, and landcover, which intrinsically add to this irregularity. Understanding how external and internal variability act to control mass fluxes requires sampling at a high spatial resolution over time, which rarely occurs in cold remote regions. In this work, we conduct five snapshot sampling surveys across 34 subcatchments during the ice‐free period in Wolf Creek Research Basin (a mesoscale montane subarctic catchment) and two additional winter surveys across a subset of sites to assess the drivers of variability in stream chemistry and discharge. We sampled for specific conductance (SpC), major ions, and dissolved organic carbon (DOC) and used statistical metrics and Bayesian mixing analysis to quantify patterns of flow and chemistry across space and time. Our results indicate patterns in both flow and chemistry remain largely consistent across seasons for all solutes. However, there was weaker correlation of chemistry between sites, suggesting asynchronous behaviour within the catchment. There was evidence of increasing production of ions and DOC along the stream network during high spring flows but not during low flows. Although concentrations and flows exhibit high seasonality in subarctic mountains, this seasonal variability does not alter spatial patterns that arise from highly variable catchment characteristics.

Proglacial lake evolution coincident with glacier dynamics in the frontal zone of Kvíárjökull, South‐East Iceland

AbstractThe termini of Icelandic glaciers are highly dynamic environments. Pronounced changes in frontal ablation in recent years have consequently changed ice dynamics. In this study, we reveal the inter‐seasonal dynamics of the Kvíárjökull ablation zone and proglacial zone using ArcticDEM and Sentinel‐2 images acquired between 2011 and 2021 and intra‐seasonal dynamics with repeated UAV surveys during summer 2021. Average glacier surface velocity in the ablation zone ranged from 51 m year−1 in 2015 up to 199 m year−1 in 2018, with maxima within the axial zone of the glacier and minima on the glacier edges. Coincidentally, and in accordance with glacier retreat/advance, the ice‐marginal proglacial lake fluctuated in its area, and we interpret that it was also a key factor in the development of the glacier terminus morphology. A complex spatial pattern of glacier surface elevation changes, including thickening in the frontal true left margin of the terminus, is interpreted to be due to variable subglacial topography, relatively fast ice flow from the accumulation zone and an insulating effect of glacier surface debris cover. In contrast, the true right (southern) part of the glacier terminus experienced thinning and retreat/disintegration also during the 2021 summer season, which we attribute to enhanced frontal ablation connected to the intrusion of lake water into the crevassed glacier terminus. Overall, this study suggests that where glaciers are developing ice‐marginal lakes complex patterns of glacier dynamics and mass loss can be expected, which will confound understanding of the short‐term evolution of these environments.

Assessing NASA-POWER Precipitation Product in Predicting Surface Flow: Lower Jhelum River Case Study

The Lower Jhelum River watershed has variable topography (i.e. northern mountains and southern plains) and a subtropical climate with hot summers and cool winters. This emphasized the extensive use of state-of-the-art POWER reanalysis precipitation product rather than gauge estimates for hydrological investigations (modeling rainfall runoff, floods, and droughts etc.). To understand the consistency and potential of the precipitation values from both sources, the primary objective of this study was to establish a relationship between POWER data and rain gauge data by utilizing 13 rain gauge stations present in the catchment. While analyzing the rainfall data, a relatively weaker linear association ( R), ranging from .6, .68 to .78, was found between the ground-based observatories and the POWER product especially for the arid and semi-arid regions. For the mountainous part, covering a wide glacial range, POWER product showed a better match with ground-based observatories that is, R value ranging from .78, .88 to .91. The simulated stream flow results by integrated HEC-HMS model showed that the POWER product can become a good asset in developing the weather data for those areas where the rain gauges are either absent or inaccessible.

Inter- and intrapopulation resource use variation of marine subsidized western fence lizards

Marine resource subsidies alter consumer dynamics of recipient populations in coastal systems. The response to these subsidies by generalist consumers is often not uniform, creating inter- and intrapopulation diet variation and niche diversification that may be intensified across heterogeneous landscapes. We sampled western fence lizards, Sceloporus occidentalis, from Puget Sound beaches and coastal and inland forest habitats, in addition to the lizards’ marine and terrestrial prey items to quantify marine and terrestrial resource use with stable isotope analysis and mixing models. Beach lizards had higher average δ13C and δ15N values compared to coastal and inland forest lizards, exhibiting a strong mixing line between marine and terrestrial prey items. Across five beach sites, lizard populations received 20–51% of their diet from marine resources, on average, with individual lizards ranging between 7 and 86% marine diet. The hillslope of the transition zone between marine and terrestrial environments at beach sites was positively associated with marine-based diets, as the steepest sloped beach sites had the highest percent marine diets. Within-beach variation in transition zone slope was positively correlated with the isotopic niche space of beach lizard populations. These results demonstrate that physiography of transitional landscapes can mediate resource flow between environments, and variable habitat topography promotes niche diversification within lizard populations. Marine resource subsidization of Puget Sound beach S. occidentalis populations may facilitate occupation of the northwesternmost edge of the species range. Shoreline restoration and driftwood beach habitat conservation are important to support the unique ecology of Puget Sound S. occidentalis.

Estimation of harbor and bay resonances by MMS-FEM model with application to the Bay of Toulon, France

Bay and harbor resonances are investigated in this work, taking into account the variable bathymetry of the semi-enclosed basin. The Modified Mild-Slope (MMS) equation is implemented for the description of combined refraction-diffraction effects, from which the eigenperiods and eigenmodes are calculated by means of a low-order Finite Element Method (FEM scheme). The model is first applied to a coastal-port region of Toulon, France, illustrating the versatility of the model to easily include coastal structures such as detached breakwater. Next, the present model is applied to the extended nearshore area of Toulon including the Gulf of Giens showing the applicability of the developed MMS-FEM model for the estimation of harbor and bay resonances, as well as more extended nearshore regions where variable bottom topography effects become important. The calculated resonant frequency depends on the domain characteristics and the size of the open sea boundary and accurately reproduces the measurements within Toulon Bay. On the other hand, for open bays such as the Gulf of Giens, a discrepancy is observed between calculated and measured eigenperiods which is due to a very wide opening of the sea boundary that cannot accurately describe the seiching. This underlines the difficulty of accurately calculating the resonance frequency for open bays, in contrast to the classic studies carried out for ports, which are considered virtually closed basins, and confirms the complementary nature of long-term water level measurements and numerical calculations, for better quantification of the risks associated with energetic meteorological and/or oceanographic events.