GIS-based models for the development of sustainable aquaculture of native fish species in central Mexico: a catchment level approach for the protection of biodiversity.

Over the last 3 decades, freshwater aquaculture has become one of the most important food industries. However the constant introduction of a reduced number of very successful species for aquaculture has been identified as one of the main activities related to the alarming decline of fish biodiversity worldwide. This issue has raised awareness amongst the scientific community, governmental authorities and the general public towards freshwater fish biodiversity. This new awareness has promoted the development of “green” markets and environmentally friendly strategies, aiming for a reliable production of protein sources. The development of native species aquaculture has been presented as a strong alternative for sustainable aquaculture and the protection of biodiversity. However, it seems clear that unplanned native species aquaculture developments can be as detrimental on local biodiversity as the introduction of exotic fish, if not more dangerous. Therefore, the advantages and disadvantages of native species aquaculture have to be clearly analysed before any aquaculture development. This study aimed to establish a philosophical background regarding the use of native fish species in aquaculture in contrast to the introduction of exotic species that may compete for a similar niche as food in local markets. The main ecological impacts that exotic fish species may have on natives, such as competition, predation, and hybridization were discussed. In addition, a well planned native species Aquaculture Strategy for the Protection of Biodiversity was produced, at catchment level, within a Geographic Information System (GIS). For the development of the native species aquaculture strategy in central Mexico, four species of Atherinids (Chirostoma estor, C. Jordani, C. promelas and Atherinella balsana) and two species of native Ictalurids (Ictalurus balsanus and Ictalurus dugesii) were included in this study. These six species are relatively new to aquaculture and they were selected on the basis of their importance in local fisheries and markets in their native basins of the Lerma-Santiago and Balsas rivers. Both of these basins are of great importance in central Mexico, not only because of their biodiversity but also because of their high human population densities and socio-economic status. The use of Geographic Information Systems was a fundamental factor in the development of the native species aquaculture strategy at catchment level, consisting of site suitability models (SSM) for each species in their corresponding native catchments. Overall, SSM identified 13,916 km2 and 11,178 km2 highly suitable for aquaculture of the studied Atherinids and Ictalurids respectively, based on Water, Soil and Terrain, Infrastructure and Risk sub-models. A set of predictive species distribution models (PSDM), which related ecological characteristics for each studied species with relevant environmental and topographic parameters into a GIS, were also produced. Such models were developed for the establishment of potential natural ranges of distribution for each species, as well as their potential to become exotic in new environments, as a potential for invasion model (PI). Based on a partial verification, both PSDM and PI models produced results that were satisfactorily consistent with the known distribution of each modelled species. The combination of SSM and PSDM produced an Aquaculture Strategy for the Protection of Biodiversity model (ASPB) which identified the most environmentally friendly suitable areas for aquaculture sites. In contrast, the combination of the SSM with PI models into an ASPB model identified the site suitability potential for non-native species that are genetically close to native ones, in an attempt to reduce the known impacts that exotic species have on local biodiversity. In this way the ASPB model identified 7,651 km2 suitable for aquaculture of I. balsanus in its native Balsas basin and 15,633 km¬2 suitable for aquaculture of the non-native I. dugesii. ASPB models were produced for all the studied species. The final results were used to produce a set of guidelines for the development of sustainable aquaculture of native species at catchment level that cover genetic and ecological implications, as well as a well planned decision making tool produced in a GIS

A composite approach to produce reference datasets for extratropical cyclone tracks: application to Mediterranean cyclones

Many cyclone detection and tracking methods (CDTMs) have been developed in the past to study the climatology of extratropical cyclones. However, all CDTMs have different approaches in defining and tracking cyclone centers. This naturally leads to cyclone track climatologies with inconsistent physical characteristics. More than that, it is typical for CDTMs to produce a non-negligible number of tracks of weak atmospheric features, which do not correspond to large-scale or mesoscale vortices and can differ significantly between CDTMs. Lack of consensus in CDTM outputs and the inclusion of significant numbers of uncertain tracks therein have long prohibited the production of a commonly accepted reference dataset of extratropical cyclone tracks. Such a dataset could allow comparable results on the analysis of storm track climatologies and could also contribute to the evaluation and improvement of CDTMs. To cover this gap, we present a new methodological approach that combines overlapping tracks from different CDTMs and produces composite tracks that concentrate the agreement of more than one CDTM. In this study we apply this methodology to the outputs of 10 well-established CDTMs which were originally applied to ERA5 reanalysis in the 42-year period of 1979-2020. We tested the sensitivity of our results to the spatiotemporal criteria that identify overlapping cyclone tracks, and for benchmarking reasons, we produced five reference datasets of subjectively tracked cyclones. Results show that climatological numbers of composite tracks are substantially lower than the ones of individual CDTMs, while benchmarking scores remain high (i.e., counting the number of subjectively tracked cyclones captured by the composite tracks). Our results show that composite tracks tend to describe more intense and longer-lasting cyclones with more distinguished early, mature and decay stages than the cyclone tracks produced by individual CDTMs. Ranking the composite tracks according to their confidence level (defined by the number of contributing CDTMs), it is shown that the higher the confidence level, the more intense and long-lasting cyclones are produced. Given the advantage of our methodology in producing cyclone tracks with physically meaningful and distinctive life stages, we propose composite tracks as reference datasets for climatological research in the Mediterranean. The Supplement provides the composite Mediterranean tracks for all confidence levels, and in the conclusion we discuss their adequate use for scientific research and applications

Survey of Non-smooth Optimisation Methods and an Evaluation of a Method for Minimax Optimisation

Computing and Information Scienc

Study of Systems and Technology for Liquid Hydrogen Production Independent of Fossil Fuels

Based on Kennedy Space Center siting and logistics requirements and the nonfossil energy resources at the Center, a number of applicable technologies and system candidates for hydrogen production were identified and characterized. A two stage screening of these technologies in the light of specific criteria identified two leading candidates as nonfossil system approaches. Conceptual design and costing of two solar-operated, stand alone systems, one photovoltaic based on and the other involving the power tower approach reveals their technical feasibility as sited as KSC, and the potential for product cost competitiveness with conventional supply approaches in the 1990 to 1210 time period. Conventional water hydrolysis and hydrogen liquefaction subsystems are integrated with the solar subsystems

A composite approach to produce reference datasets for extratropical cyclone tracks: application to Mediterranean cyclones

Many cyclone detection and tracking methods (CDTMs) have been developed in the past to study the climatology of extratropical cyclones. However, all CDTMs have different approaches in defining and tracking cyclone centers. This naturally leads to cyclone track climatologies with inconsistent physical characteristics. More than that, it is typical for CDTMs to produce a non-negligible number of tracks of weak atmospheric features, which do not correspond to large-scale or mesoscale vortices and can differ significantly between CDTMs. Lack of consensus in CDTM outputs and the inclusion of significant numbers of uncertain tracks therein have long prohibited the production of a commonly accepted reference dataset of extratropical cyclone tracks. Such a dataset could allow comparable results on the analysis of storm track climatologies and could also contribute to the evaluation and improvement of CDTMs. To cover this gap, we present a new methodological approach that combines overlapping tracks from different CDTMs and produces composite tracks that concentrate the agreement of more than one CDTM. In this study we apply this methodology to the outputs of 10 well-established CDTMs which were originally applied to ERA5 reanalysis in the 42-year period of 1979–2020. We tested the sensitivity of our results to the spatiotemporal criteria that identify overlapping cyclone tracks, and for benchmarking reasons, we produced five reference datasets of subjectively tracked cyclones. Results show that climatological numbers of composite tracks are substantially lower than the ones of individual CDTMs, while benchmarking scores remain high (i.e., counting the number of subjectively tracked cyclones captured by the composite tracks). Our results show that composite tracks tend to describe more intense and longer-lasting cyclones with more distinguished early, mature and decay stages than the cyclone tracks produced by individual CDTMs. Ranking the composite tracks according to their confidence level (defined by the number of contributing CDTMs), it is shown that the higher the confidence level, the more intense and long-lasting cyclones are produced. Given the advantage of our methodology in producing cyclone tracks with physically meaningful and distinctive life stages, we propose composite tracks as reference datasets for climatological research in the Mediterranean. The Supplement provides the composite Mediterranean tracks for all confidence levels, and in the conclusion we discuss their adequate use for scientific research and applications.</p

Prediction of the ultimate behaviour of tubular joints in offshore jacket structures using nonlinear finite element methods

PhD ThesisTubular joints are of great importance in offshore jacket structures. This thesis examines the ultimate state behaviour of tubular joints in offshore structures. In particular, the validity of a nonlinear finite element method was investigated and it was subsequently used to determine the ultimate load behaviour of a range of tubular joints. A geometrically nonlinear, eight node isoparan-letric shell finite element program is developed which allows six degrees of freedom per node. The material laws in the model include elastic and elastoplastic multilaver solution with integration across the thickness. Strain hardening elfects can be included. The nonlinear solution strategies are based on the Newton-Raphson Method. The load is applied in increments where for each step, equilibrium iterations are carried out to establish equilibrium, subject to a given error criterion. To cross the limit point and to select load increments, iterative solution strategies such as the arc length and autoniatic load increments method are adopted. To analyse tubular joints, a simple inesh generator has been developed. Struc- Cural symmetry is exploited to reduce the number of elements. The hibular joijil. is divided into a few regions and by means of a blending function. each region is discret, ised into a joints have been analysed using this finite element method. The numerical results have been compared with experimental tests undertak- en by the Wimpey Offshore Laboratory using large scale specimens. Finally, the applicabiliy of the nonlinear finite element developed here is briefly discussed all potential areas of research in the ultimate behaviour of tubular joints are proposed.British Counci

Economics of Land Degradation and Improvement – A Global Assessment for Sustainable Development

environmental economics; biodiversity; sustainable developmen