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Summary The diet of juvenile bluefin tuna (Thunnus thynnus) caught 2 to 8 miles off NE Sicily was investigated in order to improve knowledge of the species’ early life history. From 1998 to 2000, 107 specimens ranging from 63 to 495 mm (total length) were fished between July and November. Fishes were caught by trolling line or purse seine in a Fish Aggregating Devices (FADs) area 2 to 8 miles offshore and as by-catch of the purse-seine sardine fishery 2 to 4 miles offshore. Most frequently found items in the T. thynnus stomachs were fishes (84.5%), crustaceans (54.6%) and cephalopods (50.5%). The largest contribution in weight was provided by cephalopods (47.3%) and fishes (46.5%), while the most abundant items were fishes (51%), cephalopods (27.2%) and crustaceans (21.1%). These results suggest that young-of-the-year tuna have an essentially piscivorous diet, although invertebrate prey provide a substantial contribution to the food array. Prey show little relationship with FADs, although one prey species (blue runner, Caranx crysos) is associated with FADs in the Mediterranean.

The impact of plastic debris, and in particular of microplastics (here referred as particles smaller than 5 mm) on aquatic environments has now become a topic of raising concern. Microplastics are particularly abundant in the Mediterranean Sea, potentially exerting substantial pressures on marine organisms at different levels of organization. Ingestion of microplastics has been observed in a large number of marine species. The aim of this work is to test if microplastics produce a feeding impairment in Astroides calycularis, a shallow water, habitat-forming coral endemic to the Mediterranean Sea. Our findings suggest a lack of any avoidance mechanism allowing the polyps to discern between food items and microplastics when occurring simultaneously. Moreover, polyps spend a considerable amount of time on handling microplastic particles. As a consequence, microplastics impair the feeding efficiency in A. calycularis, since polyps may not be fully able to profit from the drifting plankton aggregations. Therefore, we suggest that microplastics can cause a reduction of fitness in A. calycularis, and presumably also in other species characterized by suspension feeding strategy.

Shallow-water marine organisms are among the first to suffer from combined effects of natural and anthropogenic drivers. The orange coral Astroides calycularis is a shallow-water bioconstructor species endemic to the Mediterranean Sea. Although raising conservation interest, also given its special position within the Dendrophylliidae, information about the threats to its health is scant. We investigated the health status of A. calycularis at five locations in northwestern Sicily along a gradient of cumulative human impact and the most probable origin of the threats to this species, including anthropogenic land-based and sea-based threats. Cumulative human impact appeared inversely related to the performance of A. calycularis at population, colony, and polyp levels. Sea-based human impacts appeared among the most likely causes of the variation observed. The reduction in polyp length can limit the reproductive performance of A. calycularis, while the decrease of percent cover and colony area is expected to impair its peculiar feeding behaviour by limiting the exploitable dimensional range of prey and, ultimately, reef functioning. This endangered habitat-forming species appeared susceptible to anthropogenic pressures, suggesting the need to re-assess its vulnerability status. Creating microprotected areas with specific restrictions to sea-based human impacts could be the best practice preserve these bioconstructions.

A re-examination of marine alien species or Non Indigenous Species (NIS) reported in Italian Seas, until December 2018, is provided, focusing on establishment success, year of first record, origin, potential invasiveness, and likely pathways, in particular. Furthermore, their distribution is assessed according to the marine subregions outlined by the European Union (EU) Marine Strategy Framework Directive: Adriatic Sea (ADRIA), Ionian Sea and Central Mediterranean Sea (CMED), and Western Mediterranean Sea (WMED). In Italy, 265 NIS have been detected with the highest number of species being recorded in the CMED (154 species) and the WMED (151 species) subregions, followed by the ADRIA (143) subregion. Most of these species were recorded in more than one subregion. One hundred and eighty (180 or 68%) NIS have established stable populations in Italian Seas among which 26 have exhibited invasive traits. As regards the taxa involved, Macrophyta rank first with 65 taxa. Fifty-five of them are established in at least one subregion, mostly in the ADRIA and the CMED. Crustacea rank second with 48 taxa, followed by Polychaeta with 43 taxa, Mollusca with 29 taxa, and Fishes with 28 taxa, which were mainly reported from the CMED. In the period 2012-2017, 44 new alien species were recorded, resulting in approximately one new entry every two months. Approximately half of the NIS (~52%) recorded in Italy have most likely arrived through the transport-stowaway pathway related to shipping traffic (~28% as biofoulers, ~22% in ballast waters, and ~2% as hitchhikers). The second most common pathway is the unaided movement with currents (~19%), followed by the transport-contaminant on farmed shellfishes pathway (~18%). "Unaided" is the most common pathway for alien Fishes, especially in the CMED; escapes from confinement account for ~3% and release in nature for ~2%. The present NIS distribution hotspots for new introductions were defined at the first recipient area/location in Italy. In the ADRIA, the hotspot, Venice, accounts for the highest number of alien taxa introduced in Italy, with 50 newly recorded taxa. In the CMED subregion, the hotspots of introduction are the Taranto and Catania Gulfs, hosting 21 first records each. The Strait of Sicily represents a crossroad between alien taxa from the Atlantic Ocean and the Indo-Pacific area. In the WMED, bioinvasion hotspots include the Gulfs of Naples, Genoa and Livorno. This review can serve as an updated baseline for future coordination and harmonization of monitoring initiatives under international, EU and regional policies, for the compilation of new data from established monitoring programs, and for rapid assessment surveys.

Biogenic reefs, such as those produced by tube-dwelling polychaetes of the genus Sabellaria, are valuable marine habitats which are a focus of protection according to European legislation. The achievement of this goal is potentially hindered by the lack of essential empirical data, especially in the Mediterranean Sea. This study addresses some of the current knowledge gaps by quantifying and comparing multi-scale patterns of abundance and distribution of two habitat-forming species (Sabellaria alveolata and S. spinulosa) and their associated fauna along 190 km of coast on the Italian side of the Sicily Channel. While the abundance of the two sabellariids and the total number of associated taxa did not differ at any of the examined scales (from tens of centimetres to tens-100 of kilometres), the structure (composition in terms of both the identity and the relative abundance of constituting taxa) of the associated fauna and the abundance of several taxa (the polychaetes Eulalia ornata, Syllis pulvinata, S. garciai, Nereis splendida and Arabella iricolor, and the amphipods Apolochus neapolitanus, Tethylembos viguieri and Caprella acanthifera) varied among locations established ~50e100 km apart. Syllis pulvinata also showed significant variation between sites (hundreds of metres apart), analogously to the other syllid polychaetes S. armillaris and S. gracilis, the nereidid polychaete Nereis rava, and the amphipod Gammaropsis ulrici. The largest variance of S. spinulosa, of the structure of the whole associated fauna and of 56% of taxa analysed individually occurred at the scale of replicates (metres apart), while that of the dominant bio-constructor S. alveolata and of 25% of taxa occurred at the scale of sites. The remaining 19% and the total richness of taxa showed the largest variance at the scale of locations. Present findings contribute to meet a crucial requirement of any future effective protection strategy, i.e., identifying relevant scales of variation to be included in protection schemes aiming at preserving representative samples not only of target habitats and organisms, but also of the processes driving such variability.

Anthropogenic impacts on Posidonia oceanica meadows have led to a decline of this ecosystem throughout the Mediterranean. Transplantations have often been prescribed as a compensation measure to mitigate the impacts caused by coastal maritime works. Here a Q methodology approach was used to investigate the stakeholders’ attitudes in four case studies of P. oceanica transplants realized in Italian waters. Twenty-two respondents were asked to score 37 statements, and the resultant Q-sorting was analyzed via an inverse PCA using the KADE software. Four discourses, corresponding to the significant axes in the factorial analysis were identified: science and conservation (F1), oriented at a rigorous scientific approach, engineering and industry (F2), oriented at the economic development, environmentalism and participation (F3), oriented at the conservation of seagrass meadows, and transplantation-oriented (F4), oriented at the realization of transplants as compensation measures. The main conflicts and agreements between discourses are assessed and discussed, based on the analysis of the distinguishing statements that contributed to consensus or disagreement among discourses. The benefits of the Q methodology in the identification and mediation of conflicts in the four case studies are discussed, and its potential as a powerful aid in the development of a good environmental governance is acknowledged.

In coastal marine ecosystems coralline algae often create biogenic reefs. These calcareous algal reefs affect their associated invertebrate communities via diurnal oscillations in photosynthesis, respiration and calcification processes. Little is known about how these biogenic reefs function and how they will be affected by climate change. We investigated the winter response of a Mediterranean intertidal biogenic reef, Ellissolandia elongata exposed in the laboratory to reduced pH conditions (i.e. ambient pH – 0.3, RCP 8.5) together with an extreme heatwave event (+1.4 °C for 15 days). Response variables considered both the algal physiology (calcification and photosynthetic rates) and community structure of the associated invertebrates (at taxonomic and functional level). The combination of a reduced pH with a heatwave event caused Ellisolandia elongata to significantly increase photosynthetic activity. The high variability of calcification that occurred during simulated night time conditions, indicates that there is not a simple, linear relationship between these two and may indicate that it will be resilient to future conditions of climate change. In contrast, the associated fauna were particularly negatively affected by the heatwave event, which impoverished the communities as opportunistic taxa became dominant. Local increases in oxygen and pH driven by the algae can buffer the microhabitat in the algal fronds, thus favouring the survival of small invertebrates.

The Mediterranean Sea is subject to multiple human pressures increasingly threatening its unique biodiversity. Spatially explicit information on the ecological status of marine ecosystems is therefore key to an effective maritime spatial planning and management, and to help the achievement of environmental targets. Here, we summarized scientific data on the ecological status of a selection of marine ecosystems based on a set of ecological indicators in more than 700 sites of the Mediterranean Sea. For Posidonia oceanica seagrass beds, rocky intertidal fringe, and coastal soft bottoms, more than 70% of investigated sites exhibited good to high ecological conditions. In contrast, about two-thirds of sites for subtidal rocky reefs were classified to be in moderate to bad conditions, stressing the need for prioritizing conservation initiatives on these productive and diverse environments. Very little quantitative information was available for the southern Mediterranean Sea, thus monitoring programs and assessments in this area are essential for a representative assessment of the health of marine coastal ecosystems in the whole basin. This overview represents a first step to implement a baseline that, through georeferenced data on ecological status, could help identifying information gaps, directing future research priorities, and supporting improvements to spatial models of expected cumulative impacts on marine ecosystems.

Within the framework of ecosystem-based management, restoration appears as a sensible option to counteract the global decline of coral reefs. Several techniques involving sexual and asexual coral propagules have been used for the restoration of reefs. Culturing of fragments has proved fruitful since it takes advantage of the capability of corals to asexually reproduce, providing a number of novel colonies that can be replanted. This method however, when using fragments detached from a colony, might be stressful for the wild donor. Astroides calycularis is an endemic and endangered Mediterranean scleractinian coral forming massive colonies mostly at shallow depth. It is subject to anthropogenic impact, particularly from damage due to accidental contacts by SCUBA divers, and it is expected to suffer from sea storms of increasing power under the projected climate change scenarios. Corals of opportunity (i.e. dislodged colonies found alive on the seabed) may be a useful resource for the restoration of A. calycularis reefs, given that the fragment-based transplant technique is effective for this species as it is for other massive corals. A one-year transplant experiment was carried out along an exposed rocky shore in NW Sicily (Mediterranean Sea) to test the feasibility of using fragments of corals of opportunity for restoration purposes. The transplants revealed high survival rates and higher number of new polyps than in control colonies. The original size of transplanted fragments did not influence their capability to bud new polyps and was not related to their survival rate. The applied technique provides the opportunity to restore rocky reefs, even the very shallow ones, through direct transplant of coral fragments, thus making reef restoration a feasible option in ecosystem-based management plans for this species.

The transition from a planktonic to a benthic life is a critical phase in which sub-adults are particularly exposed to the risk of predation and dispersion into unsuitable habitats, and plays a crucial role in the distribution, structure and dynamics of marine populations. Settlement involves the selection of an adequate substrate that provides shelter and food during early life stages. Percnon gibbesi is an alien brachyuran crab that has invaded the Mediterranean, where it is preferentially associated to boulders covered with shallow algal turf. The mechanisms of substrate selection leading to the settlement of megalopae are still unknown in P. gibbesi, yet their knowledge may shed light on its high invasiveness. We examined the substrate preference and settlement behaviour of 36 megalopae of P. gibbesi using three natural substrates in an experimental mesocosm: gravel, cobbles and flat stones. Video recordings of 30-min trials were used to assess the substrate preference, measure the time to selection and observe the behaviour of the megalopae. Strong preference was given to hard and stable substrates i.e., cobbles and flat stones with interstices where to hide, which are also the most suitable as they provide shelter and food. Direct selection was the dominant behaviour followed by exploration and lastly by hesitation. The megalopae selected quickly the most suitable substrate to settle, likely enhancing their chances of survival. Our findings suggest that rapid settlement on a suitable substrate contributes to the success of the biological invasion of P. gibbesi along the Mediterranean coasts.

The behavioural deficit of hatchery reared (HR) fish used for stock enhancement is the main cause of their low survival in the wild. In this study the effects of predator and shelter conditioning on survival and dispersal of HR white seabream ( Diplodus sargus ) released at sea were investigated. The hypotheses were that conditioned white seabream would avoid predators more efficiently and would be more capable to shelter, showing higher survival and smaller dispersal than naive fish. Six thousand HR white seabream (6.32 ± 0.93 cm total length) were allocated in twelve plastic tanks and divided in four experimental groups: three groups were conditioned with a predator, a refuge or both, while one group was left unconditioned and used as a control. The conditioning phase lasted 30 days and was conducted using live conger eels as predators and pyramids of perforated bricks as refuges. Flight initiation distance (FID) and time to shelter (TS) were used as response variables to test the effects of conditioning in the arena, using a dummy conger eel. The effect of conditioning on post-release survival and dispersal was assessed through the monitoring of 1465 tagged seabream belonging to the four experimental groups, released at sea. Underwater visual census was used as monitoring technique. The sighting rate (SR) (sighted fish / released fish × 100) and the distance ( D ) of each sighted fish from the release site were used as proxies for post-release survival and dispersion, respectively. In the arena, conditioned seabream showed significantly higher FID and lower TS than naive fish. At sea, the estimated post-release survival of conditioned seabreams (SR = 9.4%) was almost twice as much as that of naive individuals (SR = 5.5%). The dispersal of HR seabream acclimated to refuges from the release site ( D = 2.4 ± 3.1 km) resulted lower than in naive fish ( D = 3.7 ± 4 km). This study indicates that predator and shelter conditioning of HR white seabream is an effective practise to increase their post-release survival at sea, and our findings provide support for effective stock enhancement initiatives.

[Pachygrapsus transversus (Gibbes, 1850) is reported for the first time from Italian waters. This crab was collected at Ustica Island and at several other localities on NW Sicily (southern Tyrrhenian Sea) on vermetid reefs, an intertidal habitat frequent in the sampling area. P. transversus, whose distributional range covers the warm and warm-temperate areas of the eastern and western Atlantic and the eastern Pacific, was already known from the eastern Mediterranean since the 1920s; prior to this paper it was recorded in the western Mediterranean only in 1980 and 1994 with very few specimens.There are no data to ascertain the origin of the Sicilian population, i.e., natural or ship-mediated diffusion; either is considered possible in theory. Yet, the presence of young specimens (around 5 mm carapace length) and ovigerous females, as well as the numerical abundance at one of the Sicilian sites, suggest that the NW Sicily population is stable and well acclimatized. Pachygrapsus transversus (Gibbes, 1850) est signale pour la premiere fois dans les eaux italiennes. Ce crabe a ete recolte a l'ile d'Ustica et dans plusieurs autres localites du nord-ouest de la Sicile (partie sud de la mer Tyrrhenienne) sur des trottoirs a vermets, un habitat intertidal frequent dans la zone de recolte. P. transversus, dont la zone de distribution couvre les zones tiedes et temperees de l'Atlantique est et ouest et l'est du Pacifique etait deja connu dans l'est de la Mediterranee depuis les annees 1920; il a ete anterieurement signale dans la partie ouest de la Mediterranee seulement en 1980 et 1994 avec peu de specimens.Aucune donnee ne permet d'affirmer l'origine de la population sicilienne, naturelle ou arrivee par bateaux; en theorie les deux sont possibles. Cependant, la presence de jeunes specimens (autour de 5 mm de longueur de carapace) et de femelles ovigeres, ainsi que l'abondance numerique sur l'un des sites sicilien, suggere que la population NO de la Sicile est stable et bien acclimatee., Pachygrapsus transversus (Gibbes, 1850) is reported for the first time from Italian waters. This crab was collected at Ustica Island and at several other localities on NW Sicily (southern Tyrrhenian Sea) on vermetid reefs, an intertidal habitat frequent in the sampling area. P. transversus, whose distributional range covers the warm and warm-temperate areas of the eastern and western Atlantic and the eastern Pacific, was already known from the eastern Mediterranean since the 1920s; prior to this paper it was recorded in the western Mediterranean only in 1980 and 1994 with very few specimens.There are no data to ascertain the origin of the Sicilian population, i.e., natural or ship-mediated diffusion; either is considered possible in theory. Yet, the presence of young specimens (around 5 mm carapace length) and ovigerous females, as well as the numerical abundance at one of the Sicilian sites, suggest that the NW Sicily population is stable and well acclimatized. Pachygrapsus transversus (Gibbes, 1850) est signale pour la premiere fois dans les eaux italiennes. Ce crabe a ete recolte a l'ile d'Ustica et dans plusieurs autres localites du nord-ouest de la Sicile (partie sud de la mer Tyrrhenienne) sur des trottoirs a vermets, un habitat intertidal frequent dans la zone de recolte. P. transversus, dont la zone de distribution couvre les zones tiedes et temperees de l'Atlantique est et ouest et l'est du Pacifique etait deja connu dans l'est de la Mediterranee depuis les annees 1920; il a ete anterieurement signale dans la partie ouest de la Mediterranee seulement en 1980 et 1994 avec peu de specimens.Aucune donnee ne permet d'affirmer l'origine de la population sicilienne, naturelle ou arrivee par bateaux; en theorie les deux sont possibles. Cependant, la presence de jeunes specimens (autour de 5 mm de longueur de carapace) et de femelles ovigeres, ainsi que l'abondance numerique sur l'un des sites sicilien, suggere que la population NO de la Sicile est stable et bien acclimatee.]

Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other, unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we have identified several potential invertebrate micropredators of settlers of the sea urchin Paracentrotus lividus and measured their predation activity. Predation rates showed marked differences among species, possibly due to morphological and/or behavioral traits. Micropredators were more abundant in the forest than in barren, and their potential impact on the sea urchin community differed between the two states by two orders of magnitude. These findings suggest a novel self-perpetuating mechanism stabilizing rocky reef systems, where the abundance of micropredators may contribute to shape the sea urchin population, which in turn is responsible for the persistence of the state.

Maja goltziana d'Oliveira, 1888 is an oxyrhynch crab occurring in the eastern Atlantic Ocean from Portugal to Congo and the Canary Islands, and in the Mediterranean Sea (d'Udekem d'Acoz, 1999). It is apparently uncommon all across its distributional range, although González Pérez (1995) describes it as a frequent species on the Canary Islands. In the Mediterranean, it is by far the least common of the Maja species, among which it can easily be distinguished by the morphological characteristics of the dorsal part of the carapace and of the walking legs (see Pastore, 1983) (fig. 1). It was first recorded from the Mediterranean off the coast of Israel in the late 1950's (Holthuis & Gottlieb, 1958). In the following twenty or more years it was sparsely recorded from the Levantine basin and the Aegean Sea by only a few specimens (Ramadan & Dowidar, 1972; Koukouras, 1979; Kocatas, 1981). Later on, M. goltziana was collected in the Ionian Sea (Pastore, 1983), the Strait of Sicily (Pipitone & Tumbiolo, 1993), and the Aegean Sea (d'Udekem d'Acoz, 1994). In fact, d'Udekem d'Acoz (1999) was doubtful about the presence of this species in the Adriatic Sea, based on the record of Maja erinacea Ninni, 1924 reported by ?tev?ci´c (1990). More recently, two new records have extended the known geographic range of M. goltziana to the western Mediterranean, notably to the southern (Rinelli et al., 2000) and the northern (Vignoli et al., 2004) Tyrrhenian Sea. The present paper reports about two findings of M. goltziana in the southern Tyrrhenian, and confirms its established presence in the western Mediterranean Sea.