Spolna zrelost, stanište i ekološki aspekti rasprostranjenosti jednakonošca Sphaeroma venustissimum u tuniskim vodama

A total of 4665 specimens of Sphaeroma venustissimum Monod, 1931 were collected between February 2012 and January 2013, in Tunis Southern Lagoon, a brackish area located in northern Tunisia. This species was mainly recorded in the Atlantic Ocean and recently extended its natural range toward the southern Mediterranean Sea. Biological and ecological traits were not available to date with special regard to its native and recipient habitat. S. venustissimum isopoda inhabits area below stones covered by biofouling and empty nests of barnacles. The species occurs and reproduces in Tunis Southern Lagoon throughout the year with a peak in early spring and late summer. Males significantly outnumbered females during high reproductive activity period (May - July). The first gravid female was observed at 7 mm and the fecundity ranged between 6 and 17 eggs. Among the gravid females, a significant relationship was noted between the importance of brood versus total body length for all ovigerous female cohorts. The recruitment occurred throughout the year with a winter peak. S. venustissimum have established a sustainable population in Tunisia and have spread into the wild in its new host area.Ukupno 4665 primjeraka Sphaeroma venustissimum Monod, 1931., prikupljeno je između veljače 2012. i siječnja 2013. u tuniskoj Južnoj laguni, u bočatoj vodi koja se nalazi u sjevernom Tunisu. Ova vrsta je uglavnom zabilježena u Atlantskom oceanu, te je nedavno proširila svoj prirodni raspon prisutnosti prema južnom Sredozemnom moru. Do danas nisu bile dostupne biološke i ekološke osobitosti ovog izopoda s posebnim osvrtom na stanište i primatelje. Izopod S. venustissimum nastanjuje se ispod kamenja prekrivenih obraštajem i praznim gnijezdima rakova vitičara ispitivanja stabala kao staništa. Vrste se pojavljuju i reproduciraju u Južnoj laguni u Tunisu tijekom cijele godine s vrhuncem u rano proljeće i kasno ljeto. Mužjaci su brojčano značajno nadmašili ženke tijekom razdoblja visokog reproduktivnog djelovanja (svibanj - srpanj). Prva promatrana gravidna ženka je bila veličine 7 mm, a plodnost je iznosila između 6 i 17 jaja. Među gravidnim ženkama, zabilježena je značajna veza između važnosti legla u odnosu na ukupnu dužinu tijela za sve ženke s prekomjernom veličinom. Novačenje se odvijalo tijekom cijele godine s vrhuncem u zimskom periodu. Uspostavljene su održive populacije izopoda S. venustissimum u Tunisu, te su se proširile u divljinu kao svom novom prostoru domaćina

Spolna zrelost, stanište i ekološki aspekti rasprostranjenosti jednakonošca Sphaeroma venustissimum u tuniskim vodama

A total of 4665 specimens of Sphaeroma venustissimum Monod, 1931 were collected between February 2012 and January 2013, in Tunis Southern Lagoon, a brackish area located in northern Tunisia. This species was mainly recorded in the Atlantic Ocean and recently extended its natural range toward the southern Mediterranean Sea. Biological and ecological traits were not available to date with special regard to its native and recipient habitat. S. venustissimum isopoda inhabits area below stones covered by biofouling and empty nests of barnacles. The species occurs and reproduces in Tunis Southern Lagoon throughout the year with a peak in early spring and late summer. Males significantly outnumbered females during high reproductive activity period (May - July). The first gravid female was observed at 7 mm and the fecundity ranged between 6 and 17 eggs. Among the gravid females, a significant relationship was noted between the importance of brood versus total body length for all ovigerous female cohorts. The recruitment occurred throughout the year with a winter peak. S. venustissimum have established a sustainable population in Tunisia and have spread into the wild in its new host area.Ukupno 4665 primjeraka Sphaeroma venustissimum Monod, 1931., prikupljeno je između veljače 2012. i siječnja 2013. u tuniskoj Južnoj laguni, u bočatoj vodi koja se nalazi u sjevernom Tunisu. Ova vrsta je uglavnom zabilježena u Atlantskom oceanu, te je nedavno proširila svoj prirodni raspon prisutnosti prema južnom Sredozemnom moru. Do danas nisu bile dostupne biološke i ekološke osobitosti ovog izopoda s posebnim osvrtom na stanište i primatelje. Izopod S. venustissimum nastanjuje se ispod kamenja prekrivenih obraštajem i praznim gnijezdima rakova vitičara ispitivanja stabala kao staništa. Vrste se pojavljuju i reproduciraju u Južnoj laguni u Tunisu tijekom cijele godine s vrhuncem u rano proljeće i kasno ljeto. Mužjaci su brojčano značajno nadmašili ženke tijekom razdoblja visokog reproduktivnog djelovanja (svibanj - srpanj). Prva promatrana gravidna ženka je bila veličine 7 mm, a plodnost je iznosila između 6 i 17 jaja. Među gravidnim ženkama, zabilježena je značajna veza između važnosti legla u odnosu na ukupnu dužinu tijela za sve ženke s prekomjernom veličinom. Novačenje se odvijalo tijekom cijele godine s vrhuncem u zimskom periodu. Uspostavljene su održive populacije izopoda S. venustissimum u Tunisu, te su se proširile u divljinu kao svom novom prostoru domaćina

Unpublished Mediterranean records of marine alien and cryptogenic species

Good datasets of geo-referenced records of alien species are a prerequisite for assessing the spatio-temporal dynamics of biological invasions, their invasive potential, and the magnitude of their impacts. However, with the exception of first records on a country level or wider regions, observations of species presence tend to remain unpublished, buried in scattered repositories or in the personal databases of experts. Through an initiative to collect, harmonize and make such unpublished data for marine alien and cryptogenic species in the Mediterranean Sea available, a large dataset comprising 5376 records was created. It includes records of 239 alien or cryptogenic taxa (192 Animalia, 24 Plantae, 23 Chromista) from 19 countries surrounding the Mediterranean Sea. In terms of records, the most reported Phyla in descending order were Chordata, Mollusca, Chlorophyta, Arthropoda, and Rhodophyta. The most recorded species was Caulerpa cylindracea, followed by Siganus luridus, Magallana sp. (cf. gigas or angulata) and Pterois miles. The dataset includes records from 1972 to 2020, with the highest number of records observed in 2018. Among the records of the dataset, Dictyota acutiloba is a first record for the Mediterranean Sea. Nine first country records are also included: the alga Caulerpa taxifolia var. distichophylla, the cube boxfish Ostracion cubicus, and the cleaner shrimp Urocaridella pulchella from Israel; the sponge Paraleucilla magna from Libya and Slovenia; the lumpfish Cyclopterus lumpus from Cyprus; the bryozoan Celleporaria vermiformis and the polychaetes Prionospio depauperata and Notomastus aberans from Malta

Modélisation et Analyse des Réseaux Complexes : application à la sûreté nucléaire

This work aims to propose an adequate graph modeling approach for nuclear safety accident systems and sequences.These systems and sequences come from "Probabilistic Safety Analysis" (PSA) which is an exhaustive analysis of all possible accident scenarios, to estimate their probabilities of occurrence (by grouping them by families) and the associated consequences.Then, an analysis of the resulting networks is performed by network centrality measures. A first application consists on predicting the nuclear Risk Increase Factor, which is a PSA importance factor, using supervised learning algorithms : classification tree methods, logistic regression and ensemble learning methods, on un balanced data. Furthermore, a new synthetic centrality coefficient and a similarity measure are developed to compare the networks structures and their topological characteristics, based on their centrality vectors interdependencies. This new approach uses statistical techniques (sampling,correlation and homogeneity).The relevance and appreciation of this new measure of similarity are validated on the clustering of most popular theoretical graphs and on the prediction of the type of these graphs. Finally, an application of this approach has been conducted for the clustering of nuclear safety systems networks.Ce travail propose une modélisation adéquate en graphes pour les systèmes et séquences accidentelles de sûreté nucléaire. Ces systèmes et séquences proviennent des "Etudes Probabilistes de Sûreté" (EPS) qui consistent à analyser de façon exhaustive tous les scénarios accidentels envisageables, d’estimer leurs probabilités d’occurrence (en les regroupant par famille) et les conséquences associées.Ensuite une analyse des réseaux complexes résultants est effectuée par des mesures de centralités.Une première application consiste à la prédiction du Facteur d’Accroissement du Risque nucléaire en utilisant les algorithmes d’apprentissages supervisé : méthodes à base d’arbre de classification, régression logistique et méthodes ensemblistes, sur des données déséquilibrées.Par ailleurs, un nouveau coefficient synthétique de centralité et une mesure de similarité sont conçus pour comparer les structures de réseaux, indépendamment de leurs caractéristiques topologiques, en se basant sur les interdépendances entre leurs vecteurs de centralités.Cette nouvelle approche utilise des techniques statistiques (échantillonnage, corrélation ethomogénéité).La pertinence et l’efficacité de cette nouvelle mesure de similarité sont validées sur le clustering de graphes théoriques classiques et la prédiction du type de graphes. Enfin, une application de cette approche est réalisée pour le clustering des réseaux complexes des systèmes de sûreté nucléaire

Complex Networks Modeling and Analysis : application to Nuclear Safety

Ce travail propose une modélisation adéquate en graphes pour les systèmes et séquences accidentelles de sûreté nucléaire. Ces systèmes et séquences proviennent des "Etudes Probabilistes de Sûreté" (EPS) qui consistent à analyser de façon exhaustive tous les scénarios accidentels envisageables, d’estimer leurs probabilités d’occurrence (en les regroupant par famille) et les conséquences associées.Ensuite une analyse des réseaux complexes résultants est effectuée par des mesures de centralités.Une première application consiste à la prédiction du Facteur d’Accroissement du Risque nucléaire en utilisant les algorithmes d’apprentissages supervisé : méthodes à base d’arbre de classification, régression logistique et méthodes ensemblistes, sur des données déséquilibrées.Par ailleurs, un nouveau coefficient synthétique de centralité et une mesure de similarité sont conçus pour comparer les structures de réseaux, indépendamment de leurs caractéristiques topologiques, en se basant sur les interdépendances entre leurs vecteurs de centralités.Cette nouvelle approche utilise des techniques statistiques (échantillonnage, corrélation ethomogénéité).La pertinence et l’efficacité de cette nouvelle mesure de similarité sont validées sur le clustering de graphes théoriques classiques et la prédiction du type de graphes. Enfin, une application de cette approche est réalisée pour le clustering des réseaux complexes des systèmes de sûreté nucléaire.This work aims to propose an adequate graph modeling approach for nuclear safety accident systems and sequences.These systems and sequences come from "Probabilistic Safety Analysis" (PSA) which is an exhaustive analysis of all possible accident scenarios, to estimate their probabilities of occurrence (by grouping them by families) and the associated consequences.Then, an analysis of the resulting networks is performed by network centrality measures. A first application consists on predicting the nuclear Risk Increase Factor, which is a PSA importance factor, using supervised learning algorithms : classification tree methods, logistic regression and ensemble learning methods, on un balanced data. Furthermore, a new synthetic centrality coefficient and a similarity measure are developed to compare the networks structures and their topological characteristics, based on their centrality vectors interdependencies. This new approach uses statistical techniques (sampling,correlation and homogeneity).The relevance and appreciation of this new measure of similarity are validated on the clustering of most popular theoretical graphs and on the prediction of the type of these graphs. Finally, an application of this approach has been conducted for the clustering of nuclear safety systems networks

État de l’art des méthodes de détections de communautés dans les réseaux bipartis binaires et pondérés.

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A Complex Network Analysis Approach for Risk Increase Factor Prediction in Nuclear Power Plants

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Modélisation et Analyse des réseaux complexes : Application à la sûreté nucléaire

International audienceL'objectif de cet article est d'explorer les Etudes Probabilistes de Sûreté nucléaire (EPS) par des approches basées sur la théorie des graphes afin de leur apporter un éclairage complémentaire. Pendant les phases de design où la réalisation des EPS est impossible, cet éclairage est important

Écobiologie du bivalve invasif Fulvia fragilis (Forskal in Niehbur, 1775) des cotes tunisiennes

Ce travail traite de l éco biologie de F. fragilis (Forskal in Niehbur, 1775), bivalve lessepsien, signalé en Tunisie depuis 1996. La biologie de la reproduction a été étudiée et un suivi la croissance relative et absolue a été effectué, à deux biotopes différents (la baie de Tunis et la lagune de Bizerte). Le statut de F. fragilis en Tunisie a été établi. Les études histologiques ont révélé que c est une espèce hermaphrodite simultanée. L échelle de maturation sexuelle a été dressée. La fécondation interne et l auto fécondation sont possibles chez cette espèce. La ponte est continue sur toute l année. Ce mode de reproduction optimise le succès de l installation de l espèce mais est coûteux en énergie. D ailleurs, des mortalités estivales ont été notées et une déficience du cycle de reproduction chez F. fragilis de la lagune de Bizerte, site fortement pollué, a été observée. Le suivi de la cinétique du diamètre ovocytaire a permis la validation de l échelle de maturation sexuelle. L indice de condition constitue un bon indicateur de l état physiologique de F. fragilis. L étude de la croissance relative de F. fragilis, aux deux sites de collecte, révèle des différences majeures. La coque présente une forme plus allongée à la baie de Tunis. La croissance pondérale de ce bivalve invasif est généralement défavorisée par rapport à celle de la longueur coquillière, à Tunis, inversement à la population de Bizerte. Au second site, la croissance coquillière pourrait être affectée par la pollution. Le suivi de la croissance absolue dans les deux sites atteste que le recrutement de ce bivalve serait étalé dans le temps à Tunis et très faible à Bizerte.This work deals with the biology of Eco F. fragilis (Forskal in Niebuhr, 1775), bivalve lessepsian, reported in Tunisia since 1996. The reproductive biology has been studied and monitored the relative and absolute growth was performed at two different biotopes (the Bay of Tunis and Bizerte Lagoon). The status of F. fragilis was established in Tunisia. Histological studies have revealed that it is a simultaneous hermaphrodite. The scale of sexual maturation has been established. Internal fertilization and self fertilization are possible in this species. Spawning is continuous throughout the year. This mode optimizes reproductive success of the installation of the species but is energetically costly. Moreover, summer mortality were noted and an impaired reproductive cycle in F. fragilis from the lagoon of Bizerte, heavily polluted site, was observed. Monitor the kinetics of oocyte diameter allowed the validation of the scale of sexual maturation. The condition index is a good indicator of the physiological state of F. fragilis. The study of the relative growth of F. fragilis, the two collection sites, reveals major differences. The shell has a more elongated in the Bay of Tunis. Weight gains of this invasive bivalve is generally disadvantaged relative to the length of shellfish in Tunis, inversely to the population of Bizerte. At the second site, shell growth could be affected by pollution. Monitoring of the absolute growth in both sites confirm that the recruitment of this bivalve is spread over time in Tunis and Bizerte to very low.LORIENT-BU (561212106) / SudocSudocFranceF

Les pêcheries fixes artisanales. Etudes de cas : les chrafi de la Chebba

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