Blackspot seabream early life stages dispersal by hydrodynamic modelling (Strait of Gibraltar - Alboran Sea)

The Blackspot seabream (Pagellus bogaraveo) is a commercially appreciated demersal fish, widespread in the north-eastern Atlantic and middle-western Mediterranean. The Strait of Gibraltar (SoG) is an important fishing area where artisanal fleets from Spain and Morocco target this species using special longline gears known as “voracera”. Different studies on the health status of this species claim an overexploitation of the resource without any kind of objective management measures implemented yet by the associated countries. Improving the knowledge of the population dynamics, and particularly during the spawning window, is crucial for a better management of the fishing effort for this species. There is an agreement in literature in considering the SoG as an especially energetic and dispersive spawning zone for this species. Once spawned, eggs and larvae (ELS) are assumed to be scattered by the currents towards both sides of the SoG, mostly to the eastwards Alboran basin, where high concentrations of juveniles occur. A high resolution hydrodynamic model coupled to a Lagrangian particle tracking system is employed to assess the potential dispersal pathways of blackspot seabream ELS spawned in the SoG. Recursive releases of passive tracers in different virtual spawning spots and depths within the SoG region are tracked under different tidal conditions in order to obtain an overall characterization of the spatial dispersion patterns of the studied species. Semidiurnal tidal currents emerge as the primary factor in determining the horizontal dispersion and pathway of the spawning products, although the spring-neap tidal cycle and the spawning depth can be also important variables depending on the region considered as well as the arrival zone for the ELS dispersal paths over the Alboran SeaUniversidad de Málaga. Campus de Excelencia Internacional CEIMA

Landscapes of maritime-coastal complexity: Territorial actors, dynamics and scenarios in the Quinchao district, Chiloé Island

La presente ponencia pretende explorar la emergencia de paisajes socioterritoriales en un escenario contextual específico: el mar interior de Chiloé y, más específicamente aún, el sistema archipelágico de la Comuna de Quinchao. Utilizando un modelo teórico que recoge reflexiones e ideas de diversas disciplinas de conocimiento (filosofía, ecología social, antropología y geografía), articuladas bajo cuatro entradas teóricas (Complejidad, Estrategias de subsistencia, Modos de Habitar y Paisajes) se intenta responder la siguiente interrogante: ¿Qué paisajes emergen en la comuna de Quinchao, Isla Grande de Chiloé, a partir de los cambios experimentados/percibidos en las estrategias de subsistencia y modos de habitar?Estratégicamente, hemos decidido operar en base a unidades referenciales específicas, focalizándonos en algunas modalidades de la interacción socioambiental, como son actividades artesanales en las Áreas de Manejo y Explotación de Recursos Bentónicos (AMERB´s) y en la industria acuícola salmonera, como referentes de la actividad antrópica sobre el espacio.El objetivo principal de esta presentación es elucidar procesos de construcción de paisajes marítimos-costeros, indagando dos hipótesis:i) existen emergencias territoriales en las relaciones socioespaciales, a partir de la instauración de la industria salmonera que actualizan las opciones de estrategias de subsistencia y modos de habitar;ii) existen elementos fundamentales en la construcción de paisajes que están ligados íntimamente al proceso de “afford” o enacción, los cuales posibilitan reconocer diversas identidades del ambiente.This paper explores the emergence of socio-territorial landscapes in a specific contextual setting: the interior sea of Chiloé (Gulf of Corcovado and Gulf of Ancud) and more specifically, the archipelago in the Quinchao District. Using a theoretical model that includes reflections and ideas from various disciplines of knowledge (philosophy, social ecology, anthropology and geography) brought together under four theoretical concepts (Complexity, Subsistence Strategies, Ways of Inhabiting and Landscapes), it attempts to answer the following question: What landscapes emerge in the Quinchao District, Chiloé Island, from the changes experienced/perceived in subsistence strategies and ways of inhabiting?Strategically, the authors have decided to operate on the basis of specific reference units and focus on some forms of socioenvironmental interaction as referents of human activity on space, such as traditional activities in the Areas of Management and Exploitation of Benthic Resources (AMERB’s) and in the salmon aquaculture industry.The main objective of this work is to elucidate processes of construction of maritime-coastal landscapes by investigating two hypotheses:i) there are territorial emergencies in socio-spatial relations due to the establishment of the salmon industry that update subsistence strategy options and ways of inhabiting;ii) there are fundamental elements in the construction of landscapes that are closely linked to the process of “afford” or enaction, which make it possible to recognize the environment´s different identities

Determination of thermal conductivity variation through Modified Transient Plane Source (MTPS), and its relationship with porosity variation on thermally treated Prada limestone

In this research, the variation of thermal conductivity with temperature of a limestone and its relationship with porosity is studied. Samples from Prada formation, a lower Cretaceous limestone from the Catalan Pyrenees (Spain), obtained from the Tres Ponts road tunnel were subjected to temperatures of 105, 300, and 600 °C and then cooled at a slow rate by air-cooling to laboratory temperature. Open porosity tests were determined before and after heating to evaluate the porosity increase and the micro-cracks growth. Complementarity, thermal conductivity was measured in the rock samples before and after the application of a thermal treatment by means of C-Therm TCi device, a Modified Transient Plane Source (MTPS). This is a non-invasive, quick, and precise method, when compared with other steady-state laboratory alternatives, widely used to directly determine thermal properties of rock samples. A clear decrease in the thermal conductivity of above 10% was observed for samples heated at 600 °C, probably due to a dramatic increase in porosity. The obtained results could be of great interest for the incorporation of the effect of temperature on rock in numerical models, to evaluate the potential impacts induced by eventual fires developed inside the Tres Ponts tunnel.This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

In this investigation, two different varieties of ‘Prada’ limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400 °C: (1) the explosion of certain samples and (2) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400, and 500 °C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO2 from 400 °C. This process jointly with the presence of microfissures in the dark texture, would cause a dramatic increase in pore pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400 °C. That result also points towards a significant contribution of oxidation of pyrites on the thermo-chemical damage of the rock, among other factors such as the pre-existence of microfissures and the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bears risk for mass fracturing and dramatic strength decay from 400 °C. Moreover, SO2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.This work was supported by the Spanish Government [Grant number RTI2018-099052-B-I00] and by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Thermal effects on the drilling performance of a limestone: relationships with physical and mechanical properties

This work evaluates the effect of high temperatures and cooling methods on the drillability of Prada limestone. Samples from boreholes drilled during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) were subjected to temperatures of 105, 200, 300, 400, and 600 °C, and then cooled at a slow rate or by quenching. Sievers’ J-value (SJ) and brittleness (S20) were determined on thermally treated samples, and the drilling rate index (DRI) was calculated for each temperature. The results show that thermal treatment implied a sustained increase in the drillability of the rock of up to 40% at 600 °C and a change in the drillability category (from medium to high). At 600 °C, SJ and S20 tripled and doubled, respectively, the initial values obtained for the intact rock. The results were inconclusive about the influence of the cooling method on the drilling performance of Prada limestone for the tested range of temperatures. The substantial improvement observed in the drillability of Prada limestone when heated, measured in terms of DRI, could help in the development of novel thermally-assisted mechanical excavation methods. Additionally, strong correlations between drillability variables (i.e., SJ and S20) and physical and mechanical variables of Prada limestone (i.e., P- and S-wave velocities, uniaxial compression strength, elastic modulus, and Poisson’s ratio) are proposed. Correlations will help make preliminary predictions of drillability based on properties such as uniaxial compression strength and ultrasound wave velocities.The authors wish to acknowledge David Benavente and Juan Carlos Canaveras from the University of Alicante, for their valuable help on mineralogical and petrographic description of the rock. Additionally, Kreum SA, Ayesa SA, Infraestructures de la Generalitat de Catalunya, S.A.U., and the Lleida regional roads authority (Servei Territorial de Carreteres de Lleida, Generalitat de Catalunya) for providing rock samples. This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politecnica de Valencia

Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres

[EN] During construction of road and railway projects, expansive soils may be encountered. Their use as construction material for embankments presents difficulties, due to their tendency to swell or shrink. Traditional solutions include mixing soil with cement or quicklime, or to import materials from other locations. As an alternative to these solutions, the present paper proposes a less expensive and more sustainable solution, consisting in mixing the natural expansive soil with rubber particles obtained from scrap tyres. Especially, the Facies Tap (a typical soil of southeastern Spain) is studied in this paper. This soil, which is mainly a white argillaceous marlstone, is mixed with six different amounts of rubber content (2.5, 5, 10, 15, 20 and 25% in terms of weight) and submitted to several geotechnical tests, including compaction, free swelling, unidimensional consolidation, direct shear testing and undrained shear compression. The addition of rubber particles to the soil up to a 15% makes it lighter and less prone to swelling, while compressibility remains similar to the natural soil and the drained shear strength slightly increases. Based on experimental results, the optimum rubber content mixed with the soil to prevent its swelling is established at around 3%.Hidalgo Signes, C.; Garzón-Roca, J.; Martínez Fernández, P.; Garrido De La Torre, ME.; Insa Franco, R. (2016). Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres. Applied Clay Science. 132-133:768-773. doi:10.1016/j.clay.2016.07.027S768773132-13

Hydrodinamic connectivity and dispersal patterns in the Strait of Gibraltar: implications for a transboundary species

The blackspot seabream is a highly appreciated species that has an important target of the Spanish and Moroccan fisheries in the transcontinental waters of the Strait of Gibraltar area (Gil, 2006). It is also one of the most exploited resources of the region, which has led to a notable drop of catches over the years, arriving to a vulnerable status nowadays. Consequently, a reduction of fishing mortality towards sustainability levels was recommended (GFCM, 2021). Improving our knowledge on the interaction of this species with its physical environment is a key issue in the efforts towards rebuilding the fishery target population until its maximum sustainable yield (Cowen et al., 2006). To gain insight into this interaction, a high-resolution circulation model coupled to a lagrangian tracking module has been employed, using eggs and larvae (early-life-stages, ELS) as purely passive particles advected by simulated currents. Several spawning scenarios consisting of different temporal (tidal phase and strength) and spatial (depths and sites) initial conditions have been analyzed to identify the most likely pathways of ELS dispersion. Eastward transport by the Atlantic Jet exiting the Strait of Gibraltar is the most influencing process in that dispersion. Regarding temporal fluctuations, fortnightly tidal modulation appears to be the prevailing factor determining the horizontal paths of ELS, being the spring tide responsible of the greatest scattering of eggs and larvae. Interestingly, the spatial distribution numerically simulated is consistent with results of larvae distribution obtained from samples collected during recent scientific surveys. The results presented in this study can be certainly different attending to the species strategy. The role of other important larval traits not included in this study requires also further research that may help decision-makers to establish biological rest periods that lead to maximize connectivity and sustainability

A New SJ* Value Based on Sievers' J-Miniature Drill Tests to Determine the Drillability of Limestones

[EN] This research presents a new drillability value (SJ*) that corrects the most-used Sievers¿ J-value (SJ) by removing the accommodation effect of the drill bit in the first tenths of a millimetre to better represent the real drillability of limestones. Moreover, this research demonstrates how such an effect is more notable when porosity and micro-cracking increase, which in this study has been achieved by inducing thermal damage in the samples. To do so, limestone samples from the Prada formation were subjected to temperatures of 105, 300 and 600 °C and then cooled at fast and slow rates to induce porosity and micro-cracking. Two characteristic zones were identified in the penetration¿time plots: (a) a shallow region (Zone 1) with a variable drilling rate including an initial peak and (b) a deeper region (Zone 2) where the drilling rate stabilises. These drilling rates increase with thermally induced porosity and mi-cro-cracking, and the authors propose a new method to delimit Zones 1 and 2. Zone 1 is attributed to the time it takes for the drill bit to adjust and settle in the rock surface, while Zone 2 more realistically represents the drillability of the material. The above influ-ences the SJ value derived from Sievers¿ J-miniature drill tests, so a new drillability value SJ* is proposed that corrects SJ by ex-cluding Zone 1 and giving more weight to Zone 2. The novel SJ* presented in this research constitutes a more accurate tool to assess and predict the drilling performance in limestones.This research received no external funding. The author, Roberto Tomas, is supported by the Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital within the framework of the CIAICO/2021/335 project.Martínez Ibáñez, V.; Garrido De La Torre, ME.; Hidalgo Signes, C.; Tomás, R.; Álvarez-Fernández, M. (2023). A New SJ* Value Based on Sievers' J-Miniature Drill Tests to Determine the Drillability of Limestones. Sustainability. 16(1):1-17. https://doi.org/10.3390/su1601000811716

Predicting the Uniaxial Compressive Strength of a Limestone Exposed to High Temperatures by Point Load and Leeb Rebound Hardness Testing

The effect of exposure to high temperature on rock strength is a topic of interest in many engineering fields. In general, rock strength is known to decrease as temperature increases. The most common test used to evaluate the rock strength is the uniaxial compressive strength test (UCS). It can only be carried out in laboratory and presents some limitations in terms of the number, type and preparation of the samples. Such constrains are more evident in case of rocks from historical monuments affected by a fire, where the availability of samples is limited. There are alternatives for an indirect determination of UCS, such as the point load test (PLT), or non-destructive tests such as the Schmidt’s hammer, that can also be performed in situ. The aims of this research are: (i) measuring the effect of high temperatures and cooling methods on the strength and hardness of a limestone named Pedra de Borriol widely used in several historic buildings on the E of Spain, and (ii) studying the possibility of indirectly obtaining UCS by means of PLT and Leeb hardness tests (LHT), using Equotip type D. Limestone samples were heated to 105 (standard conditions), 200, 300, 400, 500, 600, 700, 800 and 900 ºC and cooled slowly (in air) and quickly (immersed in water). After that, UCS, PLT and LHT tests were performed to evaluate the changes as temperature increases. Results show decreases over 90% in UCS, of between 50 and 70% in PLT index and smaller than 60% in LHT index. Insignificant differences between cooling methods were observed, although slowly cooled samples provide slightly higher values than quickly cooled ones. The results indicate that LHT can be used to indirectly estimate UCS, providing an acceptable prediction. Research on correlating strength parameters in rocks after thermally treated is still scarce. This research novelty provides correlations to predict UCS in historic buildings if affected by a fire, from PLT and non-destructive methods such as LHT whose determination is quicker and easier.The authors acknowledge the support by Canteras Bernad SL which has generously provided samples, and Department of Geotechnical and Geological Engineering of Universitat Politècnica de València and Department of Civil Engineering of Universidad de Alicante, for its continuous support. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature

Biophysical Processes Determining the Connectivity of the Alboran Sea Fish Populations

This chapter revises biogeophysical issues of connectivity processes for fish populations in the Alboran Sea—Strait of Gibraltar—Gulf of Cadiz area. Connectivity of early life history stages between distant spawning grounds is crucial to incorporate vital developmental rates that condition survival probabilities at critical ontogenic stages. Hydrodynamics is pivotal to the process and most particular for pelagic species originating from adult fish adapted to recurrent patterns. Therefore, special focus has been placed on the hydrodynamics of the region, particularly on the Alboran Sea where the swift and energetic eastward-flowing Atlantic Jet entering the basin from the Strait of Gibraltar determines the surface circulation patterns. The Jet establishes an obvious zonal west-to-east connectivity, prevents the one in the opposite east-to-west direction and works as a hydrodynamic barrier that hampers the north-to-south connectivity. The chapter addresses these processes, discusses possible mechanisms to achieve connectivity between north and south shores, which have to overcome the hydrodynamic barrier, and assesses the feasibility of east-to-west connectivity by means of intermediate-depth currents. Implications on the populations and ecosystems of the Alboran Sea and on the three main harvested species potentially affected by hydrodynamic connectivity in the basin (European hake, the sardine, and the blackspot seabream) are also commented.Preprin