Listado con primeros registros de los equinodermos del norte de Túnez (Mediterráneo central)

Tunisia occupies a strategic biogeographic position in the Mediterranean Sea and the Strait of Sicily is considered a biogeographical boundary that separates the eastern and western basins. Despite the importance of marine biodiversity in Tunisia, the few studies of Echinodermata fauna in this region data from long ago. In order to update and produce a validated checklist of the echinoderms that occur in northern Tunisia, a study of this phylum was carried out between 2012 and 2016. Forty-five species were inventoried and distributed into the five living Echinodermata classes (Crinoidea, Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea). New occurrences of four species from Tunisian marine waters [Asterina pancerii (Gasco, 1876), Luidia atlantidea (Madsen, 1950), Ophiactis virens (Sars, 1859) and Leptopentacta tergestina (Sars, 1857)], are cited and discussed here for the first time.Túnez ocupa un área biogeográfica estratégica en el Mediterráneo. El estrecho tunecino-siciliano es considerado una frontera biogeográfica que separa las cubetas oriental y occidental. Sin embargo, a pesar de su interés, los estudios sobre la fauna de equinodermos de Túnez son antiguos y escasos. Con el fin de elaborar el inventario de los equinodermos de la región septentrional del mar de Túnez, se realizó un estudio de este filum entre los años 2012 y 2016. Se han inventariado cuarenta y cinco especies pertenecientes a las cinco clases actuales de Echinodermata (Crinoidea, Asteroidea, Ophiuroidea, Echinoidea y Holothuroidea). Cuatro especies [Asterina pancerii (Gasco, 1876), Luidia atlantidea (Madsen, 1950), Ophiactis virens (Sars, 1859) y Leptopentacta tergestina (Sars, 1857)] se han recolectado por primera vez en estas aguas

The reproductive biology of the school shark, Galeorhinus galeus Linnaeus 1758 (Chondrichthyes: Triakidae), from the Maghreb shore (southern Mediterranean)

The school shark, Galeorhinus galeus, is commonly captured off the Maghreb shore along the Algerian and Tunisian coasts of the southern Mediterranean. Of 517 specimens collected during more than twenty years, the smallest adult male was 1225 mm total length (TL) and weighed 11 580 g, the largest adult male was 1580 mm and weighed 18 000 g, and the heaviest male was 1570 mm and weighed 19 900 g. All males above 1260 mm TL were adult. Adult females were 1400-1900 mm TL. The smallest pregnant female was 1400 mm TL and carried developing embryos. The largest female was 1990 mm TL and weighed 27 900 g. Females were generally heavier than males, but there was no significant difference between males and females in mass versus total length relationship. Two ovulation and two pupping seasons occurred in winter and in spring. Gestation was estimated at twelve months, with most females appearing to reproduce in alternate years. The diameter of the largest yolky oocytes ranged 43-47 mm (mean 44.7±1.8) and the mass ranged 45-52 g (mean 47.9±2.2). Both uteri were compartmentalized into chambers and a single embryo developed in each chamber. Length and weight at birth, based on near-term embryos, were estimated at 240-320 mm TL and 88-109 g. The chemical balance of development, based on the mean dry mass of the largest yolky oocytes and of near-term fetuses, was about 1, showing that G. galeus can be considered as an incipient histotrophic species. Ovarian fecundity was higher than uterine fecundity. Litter sizes ranged 8-41. Males generally outnumbered females, especially among free-swimming adult specimens

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

Population structure and conservation status of the white gorgonian Eunicella singularis (Esper, 1791) in Tunisian waters (Central Mediterranean)

The white gorgonian, Eunicella singularis, is thriving in Mediterranean hard-bottom communities; however, data regarding its distribution and ecology remain absent and insufficient, particularly in the southern Mediterranean Sea. In this study, the population structure and disturbance levels of the most common gorgonian in Tunisia were assessed for the first time. During two years (2015-2016), a total of 818 colonies of E. singularis were surveyed in five coastal sites, by scuba diving, between 7 to 40 m depth. Collected data included density, colony height, and extent of injury. Mean population density was 11.91 ± 7.42 colonies per m2 (mean ± SD). Mean and maximum colony heights were 16.49 ± 5.59 cm and 51 cm, respectively. Among populations, mean extent of tissue injury differed considerably, ranging from 12.47% to 58.88% and most affected colonies showed old necrosis. These data regarding the demographic structure and level of injuries are needed to provide insights into the conservation status of the Tunisian population of E. singularis. Indeed, data on the amount of necrosis could highlight the strength of the colonies’ exposure to mechanical impacts and are consequently crucial to study changes in their demographic structure over time. In fact, the size, structures, and the high level of tissue necrosis of the colonies suggest a low conservation status of the studied Tunisian populations

O pojavi ribe šila tupokljunog Syngnathus typhle Linnaeus, 1758 (Osteichthyes: Syngnathidae) u tuniskim vodama (srednji Mediteran)

Morphometrical measurements, counts and a short description of the deep-snouted pipefish Syngnathus typhle Linnaeus, 1758 are presented in this paper from specimens caught in Tunisian waters. The occurrence of the species in the area is commented on and discussed.Morfološka mjerenja, rezultati, kratki opis ribe šila tupokljunog Syngnathus typhle Linnaeus, 1758 su dati u ovom radu prema primjercima uhvaćenim u tuniskim vodama. Također je raspravljana učestalost ove vrste na istraživanom području

Records of the critically endangered Squatina aculeata and Squatina oculata (Elasmobranchii: Squatiniformes: Squatinidae) from the Mediterranean Sea

All three species of angelsharks that inhabit the Mediterranean Sea, Squatina aculeata Cuvier, 1829; Squatina oculata Bonaparte, 1840; and Squatina squatina (Linnaeus, 1758), are classified as Critically Endangered on the IUCN Red List of Threatened Species, since their populations have suffered severe decline and range reduction, mainly due to fishing pressure. The presently reported study aims to further update records of S. aculeata and S. oculata in the basin in order to achieve a clearer picture of their current status and geographical distribution. In this way, we were able to add a contribution to our knowledge about their biological characteristics. Records on the incidental capture and observation of specimens of S. aculeata and S. oculata between 2005 and 2022 were collected through the input of alerted professional fishermen, fisher amateurs, and specialist observers on fishery landings or on board in the context of specific surveying programs as well as of citizens’ science initiatives. Biological characters such as total length, total weight, sex, and maturity were determined whenever possible. A total of 18 S. aculeata and 34 S. oculata specimens were recorded. Data corroborate the current occurrence, which is almost rare, of these two Critically Endangered elasmobranchs from the central to the east part of the basin, revealing furthermore the presence of S. aculeata in Sardinian waters, in the western part of the basin. Data document the important habitats for both species existing in the Strait of Sicily, especially in the area around Malta, and confirm the occurrence of S. aculeata in the southern Aegean Sea. The current presence of both species is also established in Mediterranean Egyptian waters. Our study suggests the urgent need for a wider application and/or reinforcement of existing protection measures for these angelshark species and their habitat, including populations of the southern Mediterranean waters.peer-reviewe

Modeling macroalgal forest distribution at Mediterranean scale : present status, drivers of changes and insights for conservation and management

Macroalgal forests are one of the most productive and valuable marine ecosystems, but yet strongly exposed to fragmentation and loss. Detailed large-scale information on their distribution is largely lacking, hindering conservation initiatives. In this study, a systematic effort to combine spatial data on Cystoseira C. Agardh canopies (Fucales, Phaeophyta) was carried out to develop a Habitat Suitability Model (HSM) at Mediterranean scale, providing critical tools to improve site prioritization for their management, restoration and protection. A georeferenced database on the occurrence of 20 Cystoseira species was produced collecting all the available information from published and grey literature, web data portals and co-authors personal data. Data were associated to 55 predictor variable layers in the (ASCII) raster format and were used in order to develop the HSM by means of a Random Forest, a very effective Machine Learning technique. Knowledge about the distribution of Cystoseira canopies was available for about the 14% of the Mediterranean coastline. Absence data were available only for the 2% of the basin. Despite these gaps, our HSM showed high accuracy levels in reproducing Cystoseira distribution so that the first continuous maps of the habitat across the entire basin was produced. Misclassification errors mainly occurred in the eastern and southern part of the basin, where large gaps of knowledge emerged. The most relevant drivers were the geomorphological ones, followed by anthropogenic variables proxies of pollution and urbanization. Our model shows the importance of data sharing to combine a large number of spatial and environmental data, allowing to individuate areas with high probability of Cystoseira occurrence as suitable for its presence. This approach encourages the use of this modeling tool for the prediction of Cystoseira distribution and for supporting and planning conservation and management initiatives. The step forward is to refine the spatial information of presence-absence data about Cystoseira canopies and of environmental predictors in order to address species-specific assessments.peer-reviewe

Gradients of genetic diversity and differentiation across the distribution range of a Mediterranean coral: Patterns, processes and conservation implications

Aim: How historical and contemporary eco-evolutionary processes shape the patterns of genetic diversity and þÿdifferentiation across species distribution range remain Focusing on the orange stony coral, Astroides calycularis, we (a) characterized the pattern of neutral genetic diversity across the distribution range; (b) gave insights into the underlying processes; and (c) discussed conservation implications with emphasis on a national park located on a hotspot of genetic diversity. Location: South Mediterranean Sea and Zembra National Park. Methods: We combined new data from 12 microsatellites in 13 populations located in the Centre and in the Western Periphery of the distribution range with a published dataset including 16 populations from the Western and Eastern Peripheries. We analysed the relationship among parameters of genetic diversity (He, Ar(g)) and structure (population-specific FST) and two measures of geographic peripherality. We compared two estimators of pairwise genetic structure (GST, DEST) across the distribution range. The evolutionary and demographic history of the populations following the Last Glacial Maximum was reconstructed using approximate Bayesian computations and maximum-likelihood analyses. We inferred the contemporary connectivity among populations from Zembra National Park and with the neighbouring area of Cap Bon. Results: We demonstrate a decrease in genetic diversity and an increase in genetic differentiation from the Centre to the Eastern and Western Peripheries of the distribution range. Populations from Zembra show the highest genetic diversity reported in the species. We identified a spillover effect towards Cap Bon. Main conclusions: The patterns of genetic diversity and þÿdifferentiation are most likely explained by the postglacial range expansion hypothesis rather than the þÿ central peripheral hypothesis. Enforcement of conservatio

Low Pufferfish and Lionfish Predation in Their Native and Invaded Ranges Suggests Human Control Mechanisms May Be Necessary to Control Their Mediterranean Abundances

The silver-cheeked toadfish (Lagocephalus sceleratus, from the pufferfish family Tetraodontidae) and the Pacific red lionfish (Pterois miles, family Scorpaenidae) have recently invaded the Mediterranean Sea. Lagocephalus sceleratus has spread throughout this entire sea with the highest concentrations in the eastern basin, while more recently, Pterois miles has spread from the Eastern to the Central Mediterranean Sea. Their effects on local biodiversity and fisheries are cause for management concern. Here, a comprehensive review of predators of these two species from their native Indo-Pacific and invaded Mediterranean and Western Atlantic ranges is presented. Predators of Tetraodontidae in general were reviewed for their native Indo-Pacific and Western Atlantic ranges, as no records were found specifically for L. sceleratus in its native range. Tetraodontidae predators in their native ranges included mantis shrimp (Stomatopoda), lizardfish (Synodus spp.), tiger shark (Galeocerdo cuvier), lemon shark (Negaprion brevirostris), sea snakes (Enhydrina spp.), catfish (Arius spp.), cobia (Rachycentron canadum), skipjack tuna (Katsuwonus pelamis), and common octopus (Octopus vulgaris). The only reported predator of adult L. sceleratus in the Mediterranean was loggerhead turtle (Caretta caretta), whereas juvenile L. sceleratus were preyed by common dolphinfish (Coryphaena hippurus) and garfish (Belone belone). Conspecific cannibalism of L. sceleratus juveniles was also confirmed in the Mediterranean. Pufferfish predators in the Western Atlantic included common octopus, frogfish (Antennaridae), and several marine birds. Predators of all lionfish species in their native Indo-Pacific range included humpback scorpionfish (Scorpaenopsis spp.), bobbit worms (Eunice aphroditois), moray eels (Muraenidae), and bluespotted cornetfish (Fistularia commersonii). Lionfish predators in the Mediterranean included dusky grouper (Epinephelus marginatus), white grouper (Epinephelus aeneus), common octopus, and L. sceleratus, whereas in the Western Atlantic included the spotted moray (Gymnothorax moringa), multiple grouper species (tiger Mycteroperca tigris, Nassau Epinephelus striatus, black Mycteroperca bonaci, red Epinephelus morio, and gag Mycteroperca microleps; Epinephelidae), northern red snapper (Lutjanus campechanus), greater amberjack (Seriola dumerilli), and nurse shark (Ginglymostoma cirratum). The sparse data found on natural predation for these species suggest that population control via predation may be limited. Their population control may require proactive, targeted human removals, as is currently practiced with lionfish in the Western Atlantic.</jats:p