El efecto del viento Mistral en la presencia y abundancia de atún rojo (Thunnus thynnus) en las almadrabas de Cerdeña (Mediterráneo Occidental)

From April to June Atlantic bluefin tuna, Thunnus thynnus, migrate along the western Sardinian coastline in a southward direction, where they are intercepted by the trap fishery. Fishermen claim that Mistral episodes facilitate the entry of tuna schools towards the traps, thus increasing capture rates. To test the fishermen’s hypothesis we conducted underwater visual counts of tuna in the trap chambers and analysed these data under the effect of wind. The results indicate a “stair-step” pattern in the abundance of tuna, demonstrating that major increases in abundance are associated with the Mistral. The second analytical approach involved a longer time scale to test whether higher Mistral occurrences corresponded to periods when higher captures were recorded. Using a linear regression model we found a significant correlation (p 15 knots seemed to have a negative effect on captures. This pattern may be caused by wind-induced advection of coastal waters generating a physical boundary that may have had a deterrent effect on tuna schools.Entre abril y junio, el atún rojo (Thunnus thynnus) emigra a lo largo de la costa oeste de Cerdeña en dirección suroeste, donde es interceptado por las almadrabas locales. Los pescadores afirman que los fuertes vientos del Noroeste (Mistral) facilitan la entrada de los bancos hacia las almadrabas incrementando las capturas. Para verificar la hipótesis de los pescadores se han contado los ejemplares de atún mediante observaciones subacuáticas y se han puesto en relación a los datos de viento recogidos en la zona. Los resultados muestran un modelo de incremento “escalonado” de abundancia en la almadraba, cuyos valores más altos corresponden a los vientos más fuertes. Para probar si los años con mayor número de días con vientos del NO se corresponden con mayor número de capturas, hemos hecho un segundo enfoque del análisis que utiliza una escala de tiempo más amplia. Mediante un modelo de regresión lineal encontramos una correlación positiva significativa (p 15 nudos parece tener un efecto negativo en las capturas. Una posible explicación que encontramos es que la advección de aguas costeras, provocada por el viento, genera una barrera física en el área de la almadraba, manteniendo los bancos alejados

El efecto del viento Mistral en la presencia y abundancia de atún rojo (Thunnus thynnus) en las almadrabas de Cerdeña (Mediterráneo Occidental)

From April to June Atlantic bluefin tuna, Thunnus thynnus, migrate along the western Sardinian coastline in a southward direction, where they are intercepted by the trap fishery. Fishermen claim that Mistral episodes facilitate the entry of tuna schools towards the traps, thus increasing capture rates. To test the fishermen’s hypothesis we conducted underwater visual counts of tuna in the trap chambers and analysed these data under the effect of wind. The results indicate a “stair-step” pattern in the abundance of tuna, demonstrating that major increases in abundance are associated with the Mistral. The second analytical approach involved a longer time scale to test whether higher Mistral occurrences corresponded to periods when higher captures were recorded. Using a linear regression model we found a significant correlation (p 15 knots seemed to have a negative effect on captures. This pattern may be caused by wind-induced advection of coastal waters generating a physical boundary that may have had a deterrent effect on tuna schools.Entre abril y junio, el atún rojo (Thunnus thynnus) emigra a lo largo de la costa oeste de Cerdeña en dirección suroeste, donde es interceptado por las almadrabas locales. Los pescadores afirman que los fuertes vientos del Noroeste (Mistral) facilitan la entrada de los bancos hacia las almadrabas incrementando las capturas. Para verificar la hipótesis de los pescadores se han contado los ejemplares de atún mediante observaciones subacuáticas y se han puesto en relación a los datos de viento recogidos en la zona. Los resultados muestran un modelo de incremento “escalonado” de abundancia en la almadraba, cuyos valores más altos corresponden a los vientos más fuertes. Para probar si los años con mayor número de días con vientos del NO se corresponden con mayor número de capturas, hemos hecho un segundo enfoque del análisis que utiliza una escala de tiempo más amplia. Mediante un modelo de regresión lineal encontramos una correlación positiva significativa (p 15 nudos parece tener un efecto negativo en las capturas. Una posible explicación que encontramos es que la advección de aguas costeras, provocada por el viento, genera una barrera física en el área de la almadraba, manteniendo los bancos alejados

Development of scientifically base management towards a sustainable fishery of the common sea urchin, Paracentrotus Lividus, in Sardinia

In recent years sea urchins have become a premium commodity in the world where both males and females of the species are harvested for their gonads, generally referred to as “roe” in the fishery and catering market. Fishing for sea urchins can be a very profitable business during the first 5 to 10 years operations on a new fishing ground. However, after that short period of time, wild populations decline due to the high efficiency and selectivity of the employed fishing techniques. In several countries fisheries declined considerably since their peaks and stocks are now likely to be over-exploited. Paracentrotus lividus is the main echinoid consumed in Mediterranean and Atlantic Europe. France is the world’s second largest consumer of sea urchin. In Italy, sea urchin fisheries occur in the South and the Islands. Recent studies suggest that the risk of collapse of the sea urchins stocks in Sardinia could be imminent, unless the fishery agencies take on immediate strategies for the species conservation. Considering such preconditions, the general aim of my PhD project have been to develop possible alternative strategies to improve the sustainability of current management practices for sea urchin fishery in Sardinia. In detail, the goal is to encourage a science-based management in order to avoid the collapse of this resource. This overarching objective has been achieved through: a) investigation the pre- and post-effects caused by fishing harvesting on spatial patterns, abundance fluctuations and total mortality rate; b) improvement of the knowledge of the effect of habitat on the ecology behaviour of the species; c) introduction of aquaculture as operational tool to improve wild stocks numbers via restocking and to provide viable alternatives to commercial fishery. The development and application of a geostatistical approach for determining the spatial distribution and resilience of P. lividus population were studied in a fishing ground of western Sardinia (Western Mediterranean). The framework proposed, combining field data collection, experimental modelling and mapping, was adequate for biomass estimation and assessment of sea urchin resource. The effect of different habitats was investigated on spine and gonad colouring and the gonad index in the purple sea urchin, Paracentrotus lividus. Colorimetric analyses of spines and gonads were conducted by a digital colorimeter using CIELAB colour spaces, which defines the colour in terms of 3 coordinate values: lightness (L*), redness (a*) and yellowness (b*). The results suggested that that habitat does affect spine colour but not gonad colour. Spine colour seems to be site dependent while the gonad index depends solely on the habitat. A land-based rearing system for sea urchins was set up in Sardinia to produce juveniles of P. lividus for restocking purposes and develop and test protocols on echiniculture. The results coming from the hatchery are promising, we obtained over 8,000 post-larvae for each of the 150 l tanks , that means at least 250,000 post-larvae will be cultured per year. In conclusion, my suggestion to guaranty the sustainability of the fishery in the future should be: 1) start a collaboratively consultative process between fishermen, researchers and policymakers to review and provide advice regarding the current management issues in order to propose a new management plan for the fishery; 2)develop a fishery-independent stock assessment in Sardinian seas; 3) develop a plan for the fishery-dependent monitoring in order to reduce/avoid the poaching and to provide appropriate data for assessment strategy; 4) testing the effectiveness of restocking by cultured juveniles in overfished areas; 5) increasing the profitability of sea urchin roe production by echiniculture, aimed to reducing harvesting pressure on wild stocks

Modelo de distribución espacial y estructura poblacional del erizo de mar Paracentrotus lividus (Echinodermata: Echinoidea) en la pesquería costera de Cerdeña occidental (Mediterráneo occidental): aplicación de un enfoque geoestadístico

The identification of appropriate spatial distribution patterns for the observation, analysis and management of stocks with a persistent spatial structure, such as sea urchins, is a key issue in fish ecology and fisheries research. This paper describes the development and application of a geostatistical approach for determining the spatial distribution and resilience of the population of the sea urchin Paracentrotus lividus in a fishing ground of western Sardinia (western Mediterranean). A framework combining field data collection, experimental modelling and mapping was used to identify the best-fit semivariogram, taking pre-fishing and post-fishing times into consideration. Variographic analyses indicate autocorrelation of density at small distances, while the isotropic Gaussian and spherical models are suitable for describing the spatial structure of sea urchin populations. The point kriging technique highlights a generally patchy population distribution that tends to disappear during the fishing season. Kriging maps are also useful for calculating predictable stock abundances, and thus mortality rates, by class diameters within six months of fishing. We conclude that the framework proposed is adequate for biomass estimation and assessment of sea urchin resources. This framework can therefore be regarded as a useful tool for encouraging a science-based management of this fishery.La identificación de modelos de distribución espacial apropiados para la observación, análisis y ordenación de los stocks con estructura espacial constante, como los erizos de mar, son temas clave en la ecología de los peces e investigación de pesquerías. El presente trabajo describe el desarrollo y aplicación de un enfoque geoespacial para determinar la distribución espacial y resistencia de la población del erizo de mar (Paracentrotus lividus) en un área pesquera al oeste de Cerdeña (Mediterráneo occidental). Se utilizó un marco que combina la recolección de datos de campo, modelos experimentales y mapas, para identificar el mejor ajuste en el semivariograma, teniendo en cuenta tiempos antes y después de la pesca. Los análisis variográficos indican una autocorrelación para la densidad a pequeñas distancias, mientras que los modelos isotrópicos Gaussianos y esféricos son apropiados para describir la estructura espacial de las poblaciones del erizo de mar. La técnica del kriging puntual destaca una distribución desigual de la población que tiende a desaparecer durante la temporada de pesca. Los mapas que utilizan kriging son también útiles para calcular una abundancia fiable del stock, y por lo tanto tasas de mortalidad por clases de diámetro en un período de seis meses de pesca. Concluimos que el marco propuesto es adecuado para la estimación de la biomasa y ordenación del recurso de erizo de mar. Por lo tanto, puede considerarse como una herramienta útil para apoyar una ordenación científica de esta pesquería

Modelo de distribución espacial y estructura poblacional del erizo de mar Paracentrotus lividus (Echinodermata: Echinoidea) en la pesquería costera de Cerdeña occidental (Mediterráneo occidental): aplicación de un enfoque geoestadístico

The identification of appropriate spatial distribution patterns for the observation, analysis and management of stocks with a persistent spatial structure, such as sea urchins, is a key issue in fish ecology and fisheries research. This paper describes the development and application of a geostatistical approach for determining the spatial distribution and resilience of the population of the sea urchin Paracentrotus lividus in a fishing ground of western Sardinia (western Mediterranean). A framework combining field data collection, experimental modelling and mapping was used to identify the best-fit semivariogram, taking pre-fishing and post-fishing times into consideration. Variographic analyses indicate autocorrelation of density at small distances, while the isotropic Gaussian and spherical models are suitable for describing the spatial structure of sea urchin populations. The point kriging technique highlights a generally patchy population distribution that tends to disappear during the fishing season. Kriging maps are also useful for calculating predictable stock abundances, and thus mortality rates, by class diameters within six months of fishing. We conclude that the framework proposed is adequate for biomass estimation and assessment of sea urchin resources. This framework can therefore be regarded as a useful tool for encouraging a science-based management of this fishery.La identificación de modelos de distribución espacial apropiados para la observación, análisis y ordenación de los stocks con estructura espacial constante, como los erizos de mar, son temas clave en la ecología de los peces e investigación de pesquerías. El presente trabajo describe el desarrollo y aplicación de un enfoque geoespacial para determinar la distribución espacial y resistencia de la población del erizo de mar (Paracentrotus lividus) en un área pesquera al oeste de Cerdeña (Mediterráneo occidental). Se utilizó un marco que combina la recolección de datos de campo, modelos experimentales y mapas, para identificar el mejor ajuste en el semivariograma, teniendo en cuenta tiempos antes y después de la pesca. Los análisis variográficos indican una autocorrelación para la densidad a pequeñas distancias, mientras que los modelos isotrópicos Gaussianos y esféricos son apropiados para describir la estructura espacial de las poblaciones del erizo de mar. La técnica del kriging puntual destaca una distribución desigual de la población que tiende a desaparecer durante la temporada de pesca. Los mapas que utilizan kriging son también útiles para calcular una abundancia fiable del stock, y por lo tanto tasas de mortalidad por clases de diámetro en un período de seis meses de pesca. Concluimos que el marco propuesto es adecuado para la estimación de la biomasa y ordenación del recurso de erizo de mar. Por lo tanto, puede considerarse como una herramienta útil para apoyar una ordenación científica de esta pesquería

La maiolica arcaica pisana a Cagliari, status quaestionis alla luce delle nuove scoperte

L’elaborato prende in considerazione le testimonianze per lo più edite di maiolica arcaica pisana a Cagliari. Il saggio è aperto da una breve introduzione sulle caratteristiche tecnico-formali, le fasi produttive e la diffusione in Sardegna. Segue l’analisi dei più rilevanti contesti di Cagliari (tra cui la chiesa di Santa Chiara, piazza San Cosimo, vico III Lanusei) e si dà particolare rilievo al contesto di San Domenico. L’obiettivo è la riconsiderazione di un importante fenomeno della cultura materiale del Basso Medioevo a Cagliari, per trarne alcune considerazioni generali sulla sua reale consistenza e commercializzazione. This is a work on the archaic pisan majolica’s evidences in Cagliari, mostly published. The essay begin with a concise introduction on this potter’s technical-morphological features, production’s stages and presences in Sardinia. Then will be take in consideration the most relevant situations in the city, as the Santa Chiara church, the San Cosimo square, the vico III Lanusei con­text and, chiefly, the San Domenico context. The objective is to re-examine a revealing phenomenon about material culture in later medieval age in Cagliari, for draw from a new viewpoint some general estimation on his true consistence and commercialization. 

Climate Change over the Mediterranean Region: Local Temperature and Precipitation Variations at Five Pilot Sites

[EN] The Mediterranean region is one of the most responsive areas to climate change and was identified as a major "hot-spot" based on global climate change analyses. This study provides insight into local climate changes in the Mediterranean region under the scope of the InTheMED project, which is part of the PRIMA programme. Precipitation and temperature were analyzed in an historical period and until the end of this century for five pilot sites, located between the two shores of the Mediterranean region. We used an ensemble of 17 Regional Climate Models, developed in the framework of the EURO-CORDEX initiative, under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Over the historical period, the temperature presents upward trends, which are statistically significant for some sites, while precipitation does not show significant tendencies. These trends will be maintained in the future as predicted by the climate models projections: all models indicate a progressive and robust warming in all study areas and moderate change in total annual precipitation, but some seasonal variations are identified. Future changes in droughts events over the Mediterranean region were studied considering the maximum duration of the heat waves, their peak temperature, and the number of consecutive dry days. All pilot sites are expected to increase the maximum duration of heat waves and their peak temperature. Furthermore, the maximum number of consecutive dry days is expected to increase for most of the study areas.This paper is supported by the PRIMA programme under grant agreement No. 1923, project Innovative and Sustainable Groundwater Management in the Mediterranean (InTheMED). The PRIMA programme is supported by the European Union.Todaro, V.; D'oria, M.; Secci, D.; Zanini, A.; Tanda, MG. (2022). Climate Change over the Mediterranean Region: Local Temperature and Precipitation Variations at Five Pilot Sites. Water. 14(16). https://doi.org/10.3390/w14162499141

Chemosensitivity in the Sea Urchin Paracentrotus lividus (Echinodermata: Echinoidea) to Food-Related Compounds: An Innovative Behavioral Bioassay

Like other animals, echinoderms rely on chemical senses to detect and localize food resources. Here, we evaluate the chemical sensitivity of the sea urchin Paracentrotus lividus to a number of stimuli possibly related to food, such as a few sugars, compared to the blue-green algae Spirulina (Arthrospira platensis). To do this we developed a simple, innovative method based on the recording of “urchinograms” estimating the movements of spines, pedicellariae, tube feet, and eventually of the whole sea urchin, in response to chemicals, while keeping both the whole animal and the stimulus in their natural environment, underwater. Our results show that Spirulina is a highly stimulating compound for the sea urchin, by acting in a dose-dependent manner. The animals resulted also sensitive, even if to a lesser extent, to some sugars, such as the monosaccharide glucose, but not to its isomer fructose, while among disaccharides, they sensed cellobiose, but not sucrose or trehalose. From an applied point of view, any insight into the chemical sensitivity of sea urchins toward potential food-related compounds may lead to the discovery of key chemicals that would help improve the efficiency and reduce the costs of dietary substrates for optimization of intensive rearing strategies. Although this method has been developed for P. lividus, it will be suitable to evaluate the chemical sensitivity of other echinoderms and other marine invertebrates characterized by low mobility