Las playas de Menorca: naturaleza y distribución

La costa de Menorca acoge 114 sistemas de playa que representan el 9,9% de la línea de costa de Menorca. Ubicadas en un ambiente micromareal y expuestas a oleajes que raras veces superan los 3m de altura significante, la mayoría de las playas menorquinas se caracterizan por presentar arenas biogénicas de medias a gruesas, estando su distribución y naturaleza condicionadas, principalmente, por el contexto morfoestructural de la isla. Tanto en lo tocante a la configuración fisiográfica de las playas y su espacio de acomodación como a la naturaleza y tipología del sedimento. En general, la tasa de evolución media de las playas de Menorca no presenta grandes problemas y se caracteriza por la estabilidad, una estabilidad reforzada por el carácter protegido o semi-protegido de las ensenadas que acogen a las playas o porque las playas más expuestas coinciden las acumulaciones de cantos y bloques al pie de acantiladosThe Menorcan coast contains 114 beach systems, which occupy 9,9% of the coastline. Menorcan beaches are characterized by a microtidal and a moderate wave energy environment where, at annual scale, in few occasions significant wave heights attend values larger than 3m. Biogenic medium to coarse sands beaches are the dominant feature, although the island morphostructure controls both: the type of beach and the sediment nature and/or texture. In average, the shoreline change rate for the island beaches shows a stability scenario reinforced by the large number of embayed and pocket beaches along the Menorcan coast. The beaches exposed to the most energetic waves tend show cobble-boulder beaches at the cliff-toeVersión del edito

Las playas de Menorca: naturaleza y distribución

La costa de Menorca acoge 114 sistemas de playa que representan el 9,9% de la línea de costa de Menorca. Ubicadas en un ambiente micromareal y expuestas a oleajes que raras veces superan los 3m de altura significante, la mayoría de las playas menorquinas se caracterizan por presentar arenas biogénicas de medias a gruesas, estando su distribución y naturaleza condicionadas, principalmente, por el contexto morfoestructural de la isla. Tanto en lo tocante a la configuración fisiográfica de las playas y su espacio de acomodación como a la naturaleza y tipología del sedimento. En general, la tasa de evolución media de las playas de Menorca no presenta grandes problemas y se caracteriza por la estabilidad, una estabilidad reforzada por el carácter protegido o semi-protegido de las ensenadas que acogen a las playas o porque las playas más expuestas coinciden las acumulaciones de cantos y bloques al pie de acantiladosThe Menorcan coast contains 114 beach systems, which occupy 9,9% of the coastline. Menorcan beaches are characterized by a microtidal and a moderate wave energy environment where, at annual scale, in few occasions significant wave heights attend values larger than 3m. Biogenic medium to coarse sands beaches are the dominant feature, although the island morphostructure controls both: the type of beach and the sediment nature and/or texture. In average, the shoreline change rate for the island beaches shows a stability scenario reinforced by the large number of embayed and pocket beaches along the Menorcan coast. The beaches exposed to the most energetic waves tend show cobble-boulder beaches at the cliff-toeVersión del edito

Physical forcing and physical/biochemical variability of the Mediterranean Sea: a review of unresolved issues and directions for future research

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries

Challenges for sustained observing and forecasting systems in the Mediterranean Sea

The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research infrastructures and private companies to implement advanced multi-platform and integrated observing and forecasting systems that facilitate the advancement of operational services, scientific achievements and mission-oriented innovation. Thus, the community can respond to societal challenges and stakeholders needs, developing a variety of fit-for-purpose services such as the Copernicus Marine Service. The combination of state-of-the-art observations and forecasting provides new opportunities for downstream services in response to the needs of the heavily populated Mediterranean coastal areas and to climate change. The challenge over the next decade is to sustain ocean observations within the research community, to monitor the variability at small scales, e.g., the mesoscale/submesoscale, to resolve the sub-basin/seasonal and inter-annual variability in the circulation, and thus establish the decadal variability, understand and correct the model-associated biases and to enhance model-data integration and ensemble forecasting for uncertainty estimation. Better knowledge and understanding of the level of Mediterranean variability will enable a subsequent evaluation of the impacts and mitigation of the effect of human activities and climate change on the biodiversity and the ecosystem, which will support environmental assessments and decisions. Further challenges include extending the science-based added-value products into societal relevant downstream services and engaging with communities to build initiatives that will contribute to the 2030 Agenda and more specifically to SDG14 and the UN’s Decade of Ocean Science for sustainable development, by this contributing to bridge the science-policy gap. The Mediterranean observing and forecasting capacity was built on the basis of community best practices in monitoring and modeling, and can serve as a basis for the development of an integrated global ocean observing system

Nearshore spatio-temporal sea surface trawls of plastic debris in the Balearic Islands

Nearshore sea-surface manta trawls were carried out monthly at seven sites along the coastline of Mallorca in the Balearic Islands in the Western Mediterranean Sea. Plastic marine debris was present in all trawls (n = 63) with an overall average abundance of 858,029 ± 4,082,964 items/km2 (mean ± standard deviation) and weight of 4,520 ± 22,806 g(DW)/km2 and the micro-plastic fraction (74%) dominating the size class. Polyethylene (LDPE and HDPE) was the most common polymer (70%) with high spatial heterogeneity, especially along the north-western coast. August showed almost two-fold as much plastic as the other months, and the number of items decreased significantly with distance from the coastline. A positive correlation was found with the fractal dimension of the coastline indicating higher coastal plastic debris retention in areas with a higher fractal dimension and backtracking simulations indicated that marine litter was mainly locally sourced. Overall results indicate a significant small scale variability of nearshore coastal marine plastic in the Balearic Islands

Characterization of changes in Western Intermediate Water properties enabled by an innovative geometry-based detection approach

Hydrographic changes in the western Mediterranean Sea (WMED), which is connected to the North Atlantic through the Strait of Gibraltar, may affect the global ocean thermohaline circulation. The Western Intermediate Water (WIW) is a regional water mass which is formed through winter convection processes in the north WMED. The variations of WIW characteristics are hardly detectable by the conventional criterion as defined in the literature and have been poorly addressed. This study introduces an innovative geometry-based method to properly detect WIW. New insights into changes in WIW properties are obtained by applying this method to glider data in the Ibiza Channel and numerical simulation in the whole WMED. Seasonal and interannual variations as well as positive trends in temperature and salinity leading to negative trend in density are highlighted in the Balearic Sea and Gulf of Lion. The basin-scale simulation also shows the spatio-temporal variability of WIW characteristics in the WMED under the influence of the location of formation site, local and regional atmospheric fluctuations, vertical mixing, horizontal advection and mixing with surrounding waters

Spatial scale, means and gradients of hydrographic variables define pelagic seascapes

Seascape ecology is an emerging discipline focused on understanding how features of the marine habitat influence the spatial distribution of marine species. However, there is still a gap in the development of concepts and techniques for its application in the marine pelagic realm, where there are no clear boundaries delimitating habitats. Here we demostrate that pelagic seascape metrics defined as a combination of hydrographic variables and their spatial gradients calculated at an appropriate spatial scale, improve our ability to model pelagic fish distribution. We apply the analysis to study the spawning locations of two tuna species: Atlantic bluefin and bullet tuna. These two species represent a gradient in life history strategies. Bluefin tuna has a large body size and is a long-distant migrant, while bullet tuna has a small body size and lives year-round in coastal waters within the Mediterranenan Sea. The results show that the models performance incorporating the proposed seascape metrics increases significantly when compared with models that do not consider these metrics. This improvement is more important for Atlantic bluefin, whose spawning ecology is dependent on the local oceanographic scenario, than it is for bullet tuna, which is less influenced by the hydrographic conditions. Our study advances our understanding of how species perceive their habitat and confirms that the spatial scale at which the seascape metrics provide information is related to the spawning ecology and life history strategy of each species.En prensa4,411

Integrating reproductive ecology, early life dynamics and mesoscale oceanography to improve albacore tuna assessment in the Western Mediterranean

Albacore tuna is a pelagic top predator of high ecological and commercial relevance worldwide. Despite the importance of this species, there is only limited knowledge of its life cycle, reproductive dynamics and early life ecology. In the Mediterranean, where the assessment is based on data-poor methods, the status of the albacore population remains uncertain. Here we combine information from commercial fisheries, ichthyoplankton surveys and oceanographic data in the Western Mediterranean Sea to identify the geographical location of the main spawning areas and larval habitats. We applied this information to develop a habitat-corrected larval abundance index providing information on early life dynamics. The larval index was compared with fisheries-dependent indices used for the stock assessment of the Mediterranean albacore. The results allowed the identification of the main spawning grounds, located around the Balearic Sea, and the role of oceanographic conditions when studying larval abundances. The larval abundance index shows a significant negative trend during the last decade, indicating a potential reduction in the spawning stock biomass, which is consistent with the trend observed from the fisheries-dependent indices. We discuss how the systematic integration of information from ichthyoplankton surveys and hydrography to improve assessment is an example of operational fisheries oceanography in practice