Governance and effects of marine reserves in the Gulf of California,Mexico

We trace the evolution, governance, and effects of three marine reserve (no-take zones) initiatives in the Gulf of California, Mexico: Loreto Bay National Park, Puerto Peñasco, and San Pedro Mártir Island Biosphere Reserve. Preliminary monitoring results, although highly variable, are encouraging for conservation and fisheries management. However, open access situations and differing conceptions among local stakeholders and government concerning access rights to fishing grounds, coupled with limited support for surveillance and lags between local and government institutional arrangements and interests, are the main constraints for the success of these and future reserves in the region. We discuss the main social–ecological feedbacks at play and the implications of our findings within a regional context.     

Interaction between seabed morphology and water masses around the seamounts on the Motril Marginal Plateau (Alboran Sea, Western Mediterranean)

The seabed morphology in the vicinity of the seamounts on the Motril Marginal Plateau (northern Alboran Sea) was investigated using high-resolution (sparker) and very high-resolution (TOPAS) seismic reflection profiles and multibeam bathymetry. The aim of the study was to determine the recent geological processes, and in particular those that control the contourite depositional system associated with the intermediate and deep Mediterranean water masses. Six groups of morphological features were identified: structural features (seamount tops, tectonic depressions), fluid escape-related features (pockmarks), mass-movement features (gullies, slides), bottom-current features (moats, scour marks, terraces, elongated and separated drifts, plastered drifts, confined drifts, sheeted drifts), mixed features (ridges) and biogenic features (including evidence of (dead) cold water corals such as Lophelia pertusa and Madrepora oculata). The main processes controlling the formation of these features are recent tectonic activity and the interaction of Mediterranean water masses with the seafloor topography. Seamounts act as topographic barriers that affect the pathway and velocity of the deep Mediterranean water masses, which are divided into strands that interact with the surrounding seafloor. The influence of the intermediate Mediterranean water mass, by contrast, is restricted mainly to the tops of the seamounts. Sediment instability and fluid-escape processes play a minor role, their occurrence being probably related to seismicity.     

A survey of groundwater quality in Tulum region,Yucatan Peninsula,Mexico

The city of Tulum, in the state of Quintana Roo (Mexico) depends almost exclusively on groundwater for water supply. The groundwater is exploited from a coastal aquifer which contains a karst network that is considered as one of the largest ones on earth. Given the nature of karst aquifers, the whole area is very sensitive to contaminants and bacteria transport, because flow paths, residence time and degradation rates differ significantly from what can be observed in the porous aquifer. The present study focuses on isotopes (¹⁸O and ²H), dissolved ions’ concentration and Escherichia coli (E. coli). The result of our survey points out the anthropic impact on groundwater quality. Furthermore, the chloride concentrations illustrate the influence of seawater mixing and geological heterogeneity over the study area. Due to an exponential growth of the tourism industry, the needs in terms of water supply and water treatment increase significantly. Tulum is a coastal city, facing a coral reef and is bordered by the Sian Ka’an biosphere reserve, therefore, an environmental issue is added to the sanitary issue, both being the basis of the local economic development. Our results show that E. coli remains a major issue, as several samples tested were contaminated, in particular those in the city center. Ions’ survey shows an anthropic impact through nitrate, phosphate and fluoride concentrations, but the obtained values are not alarming. Considering the saline intrusion, chloride concentrations indicate that the area below the Tulum city center seems to be less permeable (and maybe less karstified) than the surrounding areas, as groundwater is less subject to seawater mixing than other sampling sites at similar distance to the coast.     

Three-dimensional analysis of embankments on soft soils incorporating vertical drains by finite element method

Three-dimensional behaviour of an embankment on soft soils incorporating vertical drains is analysed by a numerical model based on the finite element method. The model, which incorporates the Biot’s consolidation theory (coupled formulation of the flow and equilibrium equations) and constitutive relations simulated by the p–q–θ critical state model, is applied on both the embankment with vertical drains (three-dimensional analysis) and the same problem but without vertical drains (two-dimensional analysis). Special emphasis is given to the analysis, during and after the construction period, of the excess pore pressures, settlements, horizontal displacements and stress levels.     

First record of fossil anguines (Squamata; Anguidae) from the Oligocene and Miocene of Turkey

Fossil anguine lizard specimens from several Turkish localities are described in this paper. The material comes from ten different localities, spanning a large geographic area consisting of both parts of the European Turkey and Anatolia, and ranging in age from the Oligocene to the Late Miocene. In certain cases, the generic determination was possible and, accordingly, members of Ophisaurus and Anguis were identified and described in detail. The specimens of Anguis, found in different, Middle and Late Miocene localities from Anatolia, represent two of only a few fossil occurrences of this taxon. Moreover, the material reported herein represents the oldest occurrences of anguine lizards, not only from Turkey, but from southeastern Europe and the Eastern Mediterranean basin as a whole. These rare records provide important information about the dispersal routes of anguines from Europe to Asia and significantly enhance our understanding of their biogeography.     

Particle transport in gravel-bed rivers: Revisiting passive tracer data

Data from tracer experiments were compiled and analysed in order to explore the role of geomorphological, hydrological and sedimentological constraints on fluvial gravel transport in gravel-bed rivers. A large data set from 217 transport episodes of tagged stones were compiled from 33 scientific papers. Our analyses showed that while magnitude of peak discharge is a major control on gravel transport and mobility, tracer travel distances show some scale dependence on the morphological configuration of the channel. Our results also highlight differences in the way tracers are displaced between step–pool and riffle and pool channels. The riffle–pool sequence seems to be a more efficient trap for travelling gravels than the step–pool pair. In addition, in step–pool channels there are clear differences in tracer transport between observations of first displacements after tracer seeding (unconstrained-stone conditions), and second and subsequent observations of tracer displacements (constrained-stone conditions). The comparison between tracer experiments under constrained conditions and those under unconstrained conditions also highlights the importance of bed state and structures in gravel mobility. The results of this study confirm that sediment transport in gravel-bed rivers is a complex process, whereby sedimentological and geomorphological controls are superimposed on the hydraulic forcing. © 2018 John Wiley & Sons, Ltd.     

Jellyfish diversity and distribution patterns in the tropical Southwestern Atlantic

Jellyfish are often the most prominent components of plankton, with severe consequences for fisheries and tourism. However, in tropical regions, there is much uncertainty about these consequences due to the lack of basic data. Our objective was to improve the knowledge about jellyfish in the Western Atlantic, with an emphasis on understanding diversity, abundance, and distribution patterns. Samples were collected at 34 stations in 1995 using a 300‐μm‐mesh Bongo net. The 21 species identified belonged to Hydromedusae (11), Siphonophora (nine), and Scyphomedusae (one). The overall mean density was low (5.2 ± 5.3 ind. m^?3). Total Hydromedusae biomass was 130.86 mg C m^?3, and total Siphonophora biomass was 19.04 mg C m^?3. Chelophyes appendiculata (Eschscholtz, 1829) was the most frequent species captured in the oceanic samples, and Aglaura hemistoma (Péron & Lesueur, 1810) was the most common in the neritic region. The latter species is sometimes characterized as a bloom associated with the most polluted and eutrophic river plumes. The main role of jellyfish species in the area is as a higher‐order carnivore. A cross‐shelf significant difference (P < 0.05) was registered, with higher species numbers in oceanic regions and higher densities and biomass in neritic regions.     

Fluid flow evolution in petroleum reservoirs with a complex diagenetic history: An example from Veracruz, Mexico

This paper discusses the fluid flow evolution in the Veracruz petroleum province of eastern Mexico based on results of an integrated diagenetic, sedimentological and structural analysis. The area progressively changed from passive foreland towards an active fold-and-thrust belt into a passive belt with infill of the foreland basin and finally underwent transpressional deformation. This varied kinematic evolution resulted in numerous fluid flow events, among which were four different petroleum migration pulses.     

A small-scale landslide susceptibility assessment for the territory of Western Carpathians

This study presented herein compares the bivariate and multivariate landslide susceptibility mapping methods and presents the landslide susceptibility map of the territory of Western Carpathians in small scale. This study also describes pioneer work for the territory of Western Carpathians, overreaching state borders, using verified sophisticated statistical methods. In the susceptibility mapping, digital elevation model was first constructed using a GIS software, and parameter maps affecting the slope stability such as geology, seismicity, precipitation, topographical elevation, slope angle, slope aspect and land cover were considered. In the last stage of the analyses, landslide susceptibility maps were produced using bivariate and multivariate analyses, and they were then compared by means of their validations. The validation of the bivariate analysis data was performed using the results of bivariate analysis for landslide areas of Slovakia containing five classes of susceptibility in scale 1:500,000. The validation area is the area of Western Carpathians within Slovakia. Eighty-two per cent of area does not differ in more than one class. The validation of the multivariate analysis data was performed using the results from the Kysuce region in the northern part of Slovakia in scale 1:10,000. The raster calculator was used to express the difference between each pair of pixels within these two layers. Seventy-seven per cent of the pixels do not differ in more than 25 %, 94 % of the pixels do not differ in more than 50 %. The maximal possible difference is 100 % (one pixel with value 0 and other with value 1, or vice versa). Receiver operating characteristic analysis was also performed, the area under curve value for bivariate model was calculated to be 0.735, while it was 0.823 for multivariate. The results of the validation can be considered as satisfactory.