Between March-May 2013 a massive Salpa maxima bloom was recorded by a citizen science study along the Ionian and Adriatic coast of the Salento peninsula (Italy). Citizen records were substantiated with field inspections along the coast and during an oceanographic campaign in the Otranto Channel. Salps clogged nets, impairing fishing activities along the coast. Swimmers were scared by the gelatinous appearance of the salps, and thought they were jellyfish. At the end of the bloom the dead bodies of the colonies, that were up to 6-7 m long, were accumulated along the coast and stirred by the waves, forming foams along dozens of kilometers of coast. The bloom also occurred at the Tremiti Islands, north of the Gargano Peninsula. The possible impacts of such events on the  functioning of pelagic systems are discussed.

Hydroids are important components of the communities of rocky bottom shallow coastal areas. The hydrozoan fauna of the Mediterranean Sea is probably one of most investigated in the world, with lots of faunistic and biogeographical studies. However, quantitative studies using the same sampling methodology and controlled sampling effort have been restricted to areas in the Western and Central Mediterranean. We compared hydroid assemblages in four areas of the Mediterranean Sea, from the Gulf of Cádiz to the South Adriatic Sea, following the same sampling and quantification methodology. Our analysis showed the dominant Atlantic character of the assemblages of the Gulf of Cádiz and the South Alboran Sea because of the influence of the inflowing Atlantic waters. Conversely, the hydroid assemblages of the North Alboran Sea were more similar to the assemblages in the Ligurian and in the South Adriatic, and with a number of species ranking between the observed in these two Mediterranean zones. Fourteen species were identified as making the most significant contributions to characterizing the Mediterranean hydroid species pool from a quantitative point of view. These taxa include species previously named as typical components of the Mediterranean hydroid fauna as well as those only recently recorded in the region (Eudendrium moulouyensis) and invaders such as Clytia hummelincki.

We present a contribution to the knowledge of marine and brackish water alien species (infraspecific taxa included) recorded along the Italian coasts. The Italian Peninsula, with over 7,000 km of coastline, is located in the center of the Mediterranean Sea, splitting the Western and the Eastern basins. Data were collected from published material, mostly authored by the experts of different marine taxa participating in the "Allochthonous Species Group" of the Italian Society of Marine Biology (SIBM). The data have been reviewed according to the taxonomic expertise of the authors and are organized in a referenced database containing information on each species about: distribution along Italian coasts, the native range, most probable vectors of introduction, population status and impact. The total number of marine alien species recorded along Italian coasts during the selected time period 1945-2009 is relatively high: 165 species, in many cases native from tropical regions of the world. Most of them were introduced in the 1980s and 1990s, whereas in the last few years the number of new records has decreased. The highest number of alien species has been observed in the northern Adriatic Sea, particularly in the Lagoon of Venice, which is the main hotspot of introduction. Of the total number of species, 46% was unable to establish resident populations in the Italian seas; 15% (24 species) rapidly increased their populations and extended their geographical range, consequently they may be considered invasive species.

Turritopsis dohrnii (Cnidaria, Hydrozoa, Hydroidolina, Anthoathecata) is the only known metazoan that is capable of reversing its life cycle via morph rejuvenation from the adult medusa stage to the juvenile polyp stage. Here, we present a complete mitochondrial (mt) genome sequence of T. dohrnii, which harbors genes for 13 proteins, two transfer RNAs, and two ribosomal RNAs. The T. dohrnii mt genome is characterized by typical features of species in the Hydroidolina subclass, such as a high A+T content (71.5%), reversed transcriptional orientation for the large rRNA subunit gene, and paucity of CGN codons. An incomplete complementary duplicate of the cox1 gene was found at the 5' end of the T. dohrnii mt chromosome, as were variable repeat regions flanking the chromosome. We identified species-specific variations (nad5, nad6, cob, and cox1 genes) and putative selective constraints (atp8, nad1, nad2, and nad5 genes) in the mt genes of T. dohrnii, and predicted alterations in tertiary structures of respiratory chain proteins (NADH4, NADH5, and COX1 proteins) of T. dohrnii. Based on comparative analyses of available hydrozoan mt genomes, we also determined the taxonomic relationships of T. dohrnii, recovering Filifera IV as a paraphyletic taxon, and assessed intraspecific diversity of various Hydrozoa species.

The organization of the cnidarian nervous system has been widely documented in polyps and medusae, but little is known about the nervous system of planula larvae, which give rise to adult forms after settling and metamorphosis. We describe histological and cytological features of the nervous system in planulae of the hydrozoan Clava multicornis. These planulae do not swim freely in the water column, but rather crawl on the substrate by means of directional, coordinated ciliary movement coupled to lateral muscular bending movements associated with positive phototaxis. Histological analysis shows pronounced antero-posterior regionalization of the planula’s nervous system, with a different neural cell types highly concentrated at the anterior pole. Transmission electron microscopy of planulae shows the nervous system to be unusualy complex, with a large orderly array of sensory cells at the anterior pole. In the anterior half of the planula the basi-ectodermal plexus of neurites forms an extensive orthogonal network, whereas more posteriorly neurites extend longitudinally along the body axis. Additional levels of nervous system complexity are uncovered by neuropeptide-specific immunocytochemistry, which reveal distinct neural subsets having specific molecular phenotypes. Together these observations imply that the nervous system of planulae of Clava multicornis manifests a remarkable level of histological, cytological and functional organization, whose features may be reminiscent of those present in early bilaterian animals.

The increasing frequency of jellyfish outbreaks in coastal areas has led to multiple ecological and socio-economic issues, including mass mortalities of farmed fish. We investigated the sensitivity of the European sea bass (Dicentrarchus labrax), a widely cultured fish in the Mediterranean Sea, to the combined stressors of temperature, hypoxia and stings from the jellyfish Pelagia noctiluca, through measurement of oxygen consumption rates (MO2), critical oxygen levels (PO2crit), and histological analysis of tissue damage. Higher levels of MO2, PO2crit and gill damage in treated fish demonstrated that the synergy of environmental and biotic stressors dramatically impair farmed fish metabolic performances and increase their health vulnerability. As a corollary, in the current scenario of ocean warming, these findings suggest that the combined effects of recurrent hypoxic events and jellyfish blooms in coastal areas might also threaten wild fish populations.

In recent years, caged finfish mariculture across European seas suffered production losses by severe fish mortality, following episodic outbreaks of invertebrate cnidarian stingers. Due to their stinging cells and injectable venoms, medusozoan jellyfish or drifting propagules of polyp colonies at high density may impair caged fish health through toxic effects on vulnerable tissues of gills and skin, and related secondary bacterial infections. Gill disorders in European sea bass (Dicentrarchus labrax) fish farms along the Spanish Mediterranean coast are commonly reported, but regular monitoring of the frequency of cnidarian outbreaks and their potential impacts on caged fish is still poorly enforced. In this study, two sea bass mariculture farms in Southern Spain (Málaga; Almería) were monitored biweekly for zooplankton, phytoplankton and fish gills condition, over 13 or 30 months for the Málaga and Almería facilities respectively, within the period 2012 – 2014. Significant, direct correlations were found among low water temperature, recorded fish mortalities, and high abundances of planktonic cnidarians, particularly of the hydrozoan siphonophores Muggiaea atlantica and M. kochii, and the larval stage of Ectopleura larynx, a common member of cage biofouling communities. A significant relationship between cnidarian densities and the quantitative scoring of gill pathology was also observed. In addition, high densities of long-bristled planktonic diatoms (Chaetoceros spp.) coincided with a major fish mortality event (April 2012, Almería farm). Standardised monitoring of plankton dynamics and composition may help in promoting response capacities of Mediterranean mariculture managers to fish health challenges (such as stinging plankton blooms) by a) improving diagnostic tools and preventative countermeasures and b) supporting the development of science-based spatial planning and sustainable growth of coastal mariculture.

The patchy distribution pattern of benthic hydrozoans reflects high sensitivity of colonies to local and micro-scale environmental factors, which may affect the outcome of biodiversity inventories based on different sampling methodologies. We compared three quantitative sampling methods for benthic hydrozoans, differing for strategy (scraping standardized surfaces or picking visually located colonies) and tactics (extension of examined surface). Each of the three methods consisted of eight replicate samplings to compare relative and absolute method efficiencies, also in terms of minimum sampling area representative of the hydroid diversity in the study site. A single horizontal belt transect on a vertical rocky cliff was chosen at 15 m depth near Otranto (South Adriatic). A total of 37 species were identified by the three methods and their relative abundances were evaluated. The hydroid assemblage was dominated by generalist species with high polyp numbers able to colonize different substrata. We compared the outcomes of each of the three sampling methods, and by a cost-benefit analysis we identified the optimal sampling methods to be adopted according to the different targets of the investigations. On data standardized to the same total sampled areas, the three sampling methods did not originate significant differences in the number of polyps of each recorded species (PDA, Polyp Detection Ability), whereas the visually-oriented collection (VIS) and the scrapings over 20 × 20 cm standard surfaces (S20) were more effective in the detected number of species (SDA, Species Detection Ability) than over 10 × 10 cm squares (S10). For ecological purposes, samplings based on five S20 replicates can be considered an appropriate experimental design to get a statistically robust representation of the studied hydroid assemblage at Punta Palascia. However, variation in depth, exposure and geographical locations may require different sampling approaches, and pre-surveys should be always carried out before addressing taxonomical surveys of sessile organisms.

Jellyfish outbreaks are increasingly viewed as a deterministic response to escalating levels of environmental degradation and climate extremes. However, a comprehensive understanding of the influence of deterministic drivers and stochastic environmental variations favouring population renewal processes has remained elusive. This study quantifies the deterministic and stochastic components of environmental change that lead to outbreaks of the jellyfish Pelagia noctiluca in the Mediterranen Sea. Using data of jellyfish abundance collected at 241 sites along the Catalan coast from 2007 to 2010 we: (1) tested hypotheses about the influence of time-varying and spatial predictors of jellyfish outbreaks; (2) evaluated the relative importance of stochastic vs. deterministic forcing of outbreaks through the environmental bootstrap method; and (3) quantified return times of extreme events. Outbreaks were common in May and June and less likely in other summer months, which resulted in a negative relationship between outbreaks and SST. Cross- and along-shore advection by geostrophic flow were important concentrating forces of jellyfish, but most outbreaks occurred in the proximity of two canyons in the northern part of the study area. This result supported the recent hypothesis that canyons can funnel P. noctiluca blooms towards shore during upwelling. This can be a general, yet unappreciated mechanism leading to outbreaks of holoplanktonic jellyfish species. The environmental bootstrap indicated that stochastic environmental fluctuations have negligible effects on return times of outbreaks. Our analysis emphasized the importance of deterministic processes leading to jellyfish outbreaks compared to the stochastic component of environmental variation. A better understanding of how environmental drivers affect demographic and population processes in jellyfish species will increase the ability to anticipate jellyfish outbreaks in the future.

Surface-dwelling colonies ofVelella velellaoccur throughout tropical to cold-temperate oceans of the world and some-times are stranded in masses along hundreds of kilometers of beaches. Large-scale blooms in the WesternMediterranean Sea in 2013 and 2014 allowed the study of diet, prey digestion times and predation rates. Gastrozooidcontent analyses showed that 59% of the 769 identified prey were euphausiid larvae (calytopsis and furcilia) capturedat night. Copepods (41%), fish eggs (2.2%) and larvae (0.5%) were captured both at day and night. Digestion times atambient temperature (178C) of calytopsis, furcilia and copepods were estimated to be.6.5, 4.4 and 3.9 h, respect-ively. Estimated prey consumption was substantially lower in 2014 than in 2013 (41 vs. 75 prey day21colony21).Velella velellaand other gelatinous species bloomed in the Mediterranean Sea and the northeastern Atlantic and Pacificoceans in 2013 and 2014. Because of the wide distribution ofV. velellacolonies, their mass occurrences, potential im-portance as predators and competitors of fish, additional production from symbiotic zooxanthellae and stranding onbeaches, they could be important in open-ocean carbon cycling and in transport of pelagic production to landmasses.

Polyps of two moon jellyfish species, Aurelia coerulea and A. relicta, from two Adriatic Sea coastal habitats were incubated under multiple combinations of temperature (14, 21°C), salinity (24, 37 ppt) and food regime (9.3, 18.6, 27.9 μg C ind−1 week−1) to comparatively assess how these factors may influence major asexual reproduction processes in the two species. Both species exhibited a shared pattern of budding mode (Directly Budded Polyps: DBP; Stolonal Budded Polyps: SBP), with DBP favoured under low food supply (9.3 μg C ind −1 week−1) and low temperature (14°C), and SBP dominant under high temperature (21°C). However, A. coerulea showed an overall higher productivity than A. relicta, in terms of budding and podocyst production rates. Further, A. coerulea exhibited a wide physiological plasticity across different temperatures and salinities as typical adaptation to ecological features of transitional coastal habitats. This may support the hypothesis that the invasion of A. coerulea across coastal habitats worldwide has been driven by shellfish aquaculture, with scyphistoma polyps and resting stages commonly found on bivalve shells. On the contrary, A. relicta appears to be strongly stenovalent, with cold, marine environmental optimal preferences (salinity 37 ppt, T ranging 14–19°C), corroborating the hypothesis of endemicity within the highly peculiar habitat of the Mljet lake. By exposing A. relicta polyps to slightly higher temperature (21°C), a previously unknown developmental mode was observed, by the sessile polyp regressing into a dispersive, temporarily unattached and tentacle-less, non-feeding stage. This may allow A. relicta polyps to escape climatic anomalies associated to warming of surface layers and deepening of isotherms, by moving into deeper, colder layers. Overall, investigations on species-specific eco-physiological and ontogenetic potentials of polyp stages may contribute to clarify the biogeographic distribution of jellyfish and the phylogenetic relationships among evolutionary related sister clades.

Abstract: In recent years, several episodes of mass mortality of sessile epibenthic invertebrates, including sponges, have been recorded worldwide. In the present study, we report a disease event on Ircinia variabilis recorded in September 2009 along the southern Adriatic and Ionian seas (Apulian coast), with the aim to quantify the mortality incidence on the sponge population, to investigate the effect of the disease on the sponge tissues and to assess whether the disease is associated with vibrios proliferation. The injured sponges showed wide necrotic areas on the surface or disruption of the body in several portions. Necrotic areas were whitish and often were covered with a thin mucous coat formed by bacteria. In the most affected specimens, sponge organisation resulted partial or complete loss, with the final exposure of the dense skeletal network of spongine fibres to the environment. The results of microbiological cultural analysis using in parallel Marine Agar 2216 and thiosulphate/citrate/bile salts/sucrose agar demonstrated that, in affected specimens, vibrios represented 15.8 % of the total I. variabilis surface culturable bacteria. Moreover, all the isolated vibrios, grown from the wide whitish areas that characterize the surface of the diseased sponges, were identified, and their assignment to the Vibrio rotiferianus was consistent with phylogenetic analysis and data of morphological, cultural and biochemical tests. Studies on V. rotiferianus have shown that its pathogenicity, with respect to various aquatic organisms, is higher than that of Vibrio harveyi. The factors triggering the disease outbreak in Ircinia variabilis populations remain unclear. At present, we can hypothesize the involvement in the disease of a synergetic mechanism that, under stressful physiological conditions (high temperature, elevated nutrients and reduced water flow), induces sponge pathogens, in our case V. rotiferanius, to become virulent, making sponges unable to control their proliferation. Additional studies are needed to understand the etiological processes as well as the factors involved in sponges recovering from this epidemic event allowing them to face mass mortality. A drastic reduction of sponge-specific representatives could have marked a negative impact on the environmental health on account of their role in the sea remediation processes as filter-feeding organisms.

Erratum to: Biol Invasions DOI 10.1007/s10530-010-9803-y

On a global scale, jellyfish populations in coastal marine ecosystems exhibit increasing trends of abundance. High-density outbreaks may directly or indirectly affect human economical and recreational activities, as well as public health. As the interest in biology of marine jellyfish grows, a number of jellyfish metabolites with healthy potential, such as anticancer or antioxidant activities, is increasingly reported. In this study, the Mediterranean “fried egg jellyfish” Cotylorhiza tuberculata (Macri, 1778) has been targeted in the search forputative valuable bioactive compounds. A medusa extract was obtained, fractionated, characterized by HPLC, GC-MS and SDS-PAGE and assayed for its biological activity on breast cancer cells (MCF-7) and human epidermal keratinocytes (HEKa). The composition of the jellyfish extract included photosynthetic pigments, valuable ω-3 and ω-6 fatty acids, and polypeptides derived either from jellyfish tissues and their algal symbionts. Extract fractions showed antioxidant activity and the ability to affect cell viability and intercellular communication mediated by gap junctions (GJIC) differentially in MCF-7and HEKa cells. A significantly higher cytotoxicity and GJIC enhancement in MCF-7 compared to HEKa cells was recorded. A putative action mechanism for the anticancer bioactivity through the modulation of GJIC has been hypothesized and its nutraceutical and pharmaceutical potential was discussed

Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatio-temporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environments.

The hydroid fauna of the Mediterranean Sea is considered one of the best known in the world, but the hydrozoans of the Aegean Sea remain poorly studied, hindering efforts to identify alien and invasive species in the region. The spatial and seasonal composition of the shallow-water (0–20 m depth) benthic hydrozoan assemblage from Gökçeada Island was investigated in summer 2012 and winter 2013. Overall, 48 hydrozoan taxa were identified, and their presence and ecological features are discussed herein. Twelve species are recorded for the first time in the Aegean Sea, and the same number for the Turkish coasts. Differences in species composition were detected between the northern and southern coasts of Gökçeada by cluster, multidimensional scaling (MDS) and permutational multivariate analysis of variance (PERMANOVA) analysis, whereas seasonal and vertical distribution patterns were not statistically significant. Differences in species richness and composition between the northern and southern coasts may be explained by the distinct geomorphological aspects of the shores, providing a spatial heterogeneity in the availability of substrates for the hydroid colonies. Observed differences are attributable to the occurrence and/or abundance of common species such as Sertularella ellisii, Aglaophenia tubiformis, Clytia hemisphaerica, Clytia linearis, Eudendrium racemosum, Plumularia obliqua, Eudendrium capillare, Turritopsis dorhnii and Dynamena disticha, rather than to the presence of rare, exclusive species.

The cubozoan jellyfish Carybdea marsupialis Linnaeus, 1758 is recorded for the first time from the eastern Tunisian coast (Hammamet beach). A few specimens (three adult individuals) were first recorded in July 2005. In spite of several jellyfish monitoring campaigns carried out along the Tunisian coasts in recent years, new records of C. marsupialis from the same location were only made years later, in July and August 2014, consisting of aggregations of adult jellyfish (mean density of 1.1 ± 1.0 ind. m−3), which may pose a severe threat to bathers due to their painful stings. The mean morphometric parameter values from 55 C. marsupialis specimens sampled during the same period are reported here, and the possible causes for box jellyfish proliferation in the Hammamet coastal zone are also discussed.

The Australian spotted scyphomedusa Phyllorhiza punctata was recorded for the first time in Tunisian waters in August 2012, in the lagoon of Bizerte (Tunisia). Metaephyrae and juveniles occurred simultaneously in August 2012. The occurrence of adult medusae was detected from September to November 2012, and from August to October 2013. This is the second record of a reproducing population of P. punctata in the Mediterranean Sea. The low abundance of mesozooplankton in summer and autumn 2012 coincides temporally with the highest density of P. punctata recorded in the lagoon, suggesting that predation by this alien jellyfish may have been a limiting factor for the mesozooplankton abundance on site.

Laboratory experiments documenting the decomposition pattern of extant organisms are used to reconstruct the anatomy and taphonomy of fossil taxa. The subclass Graptolithina (Hemichordata: Pterobranchia) is a significant fossil taxon of the Palaeozoic era, represented by just one modern genus, Rhabdopleura. The rich graptolite fossil record is characterized by an almost total absence of fossil zooids. Here we investigated the temporal decay pattern of Rhabdopleura sp. tubes, stolons and single zooids removed from the tubarium. Tubes showed decay after four days, when fuselli began to separate from the tube walls. This rapid loss may explain the absence of fuselli from some graptolite fossils. The black stolon did not show decay until day 155. One day after their removal, zooids quickly decomposed in the following temporal sequence: (1) tentacles; (2) ectoderm; (3) arms; (4) gut; (5) cephalic shield, leading to complete disappearance of recognizable body parts in the majority of experimental zooids within 64–104 h. The most resistant zooid features to decay (61 days) were black-pigmented granules. These results indicate that tubes and the black stolon would persist for weeks across death, transport and burial, whereas a complete decay of zooid features occurs in few days, providing an explanation for the overall poor record of fossil graptolite zooids and suggesting that recorded silhouettes of fossil zooids may be attributed to fossil decay-resistant pigments.

The origin of multicellular animals and how multicellularity evolved is one of those difficult and delicate biological problems that has been pondered over for centuries. This book attempts to summarize some of the more recent results in phylogenetics and developmental biology that address the evolution of key innovations in metazoans. The book has three main sections. The first section contains five chapters that address the phylogenetic issues involving this part of the tree of life. Even though modern genome technology has made it possible to study these issues using a vast information database the elucidation of the relationships in this part of the tree of life continues to be elusive. The second section of the book addresses some of the more prominent questions concerning the developmental biology of metazoan evolution. The topics in this section focus on nervous system development, sensory organ development and developmental systems. The third section of the book focuses on the evolution of pattern and process in the incredible forms of life that we call Metazoa. The topics covered in this part of the book include the evolution of life histories, ecological associations and the evolution of biogeochmical aspects of metazoa. The book has over 40 illustrations and an up to date bibliography of over 500 references. Each chapter concludes with a set of questions for study and discussion to assist instructors and students in delving more deeply into the topics covered by the seventeen chapters in the book. Table of Contents Introduction: A Phylogenomic Journey Through the Animal Tree of Life: Key Innovations in the Evolution of Metazoa; B. Schierwater and R. DeSalle Tangled Roots in the Animal Tree of Life Putting Animals in their Place Within a Context of Eukaryotic Innovations; D. Vazquez, L. Wegener Parfrey and L.A. Katz Elucidating Animal Phylogeny: Advances in Knowledge and Forthcoming Challenges; K.M. Kocot, J.T. Cannon and K.M. Halanych Key Transitions in Animal Evolution: a Mitochondrial DNA Perspective; D.V. Lavrov Pending Issues in Development and Phylogeny of Arthropods; J.S. Deutsch The Earliest Animals: From Genes to Transitions The Pre-nervous System and Beyond—Poriferan Milestones in the Early Evolution of the Metazoan Nervous System; M. Nickel A Key Innovation in Evolution, the Emergence of Neurogenesis: Cellular and Molecular Cues from Cnidarian Nervous Systems; B. Galliot, M. Quiquand, M. Miljkovic-Licina and S. Chera From Cnidaria to "Higher Metazoa" in One Step; F. Boero and S. Piraino Basal Metazoan Sensory Evolution; D.K. Jacobs, D.A. Gold, N. Nakanishi, D. Yuan, A. Camara, S.A. Nichols and V. Hartenstein Cnidarian Gene Expression Patterns and the Origins of Bilaterality—Are Cnidarians Reading the Same Game Plan as "Higher" Animals?; E.E. Ball, D.M. de Jong, B. Schierwater, C. Shinzato, D.C. Hayward and D.J. Miller Key Transitions During Animal Phototransduction Evolution: Co-duplication as a Null Hypothesis for the Evolutionary Origins of Novel Traits; T.H. Oakley and D.C. Plachetzki Vertebrate Hox Genes and Specializations in Mammals; C. Kappen Pattern and Process at the Base of the Metazoan Tree of Life Field Biology of Placozoans (Trichoplax): Distribution, Diversity, Biotic Interactions; V. Buchsbaum Pearse and O. Voigt Trichoplax and Placozoa: One of the Crucial Keys to Understanding Metazoan Evolution; B. Schierwater et al. A Food’s-Eye View of Animal Transitions; N.W. Blackstone Lost in Transition: The Biogeochemical Context of Animal Origins; E. Gaidos Redefining Stem Cells and Assembling Germ Plasm: Key Transitions in the Evolution of the Germ Line; J. Srouji and C. Extavour Questions and Discussion

Sessile hydrozoans constitute a common component of marine rocky communities. We compared the hydrozoan assemblages occurring on sea-walls of commercial harbours with those on natural rocky cliffs along the southern Iberian Peninsula, to identify differences in the multivariate structure of the assemblages and species richness. Harbour hydroid assemblages significantly differed from natural ones mainly due to their qualitative composition. Medusa-less taxa, optimized for low dispersal and long-term persistence on the substratum, are barely represented in harbours, but abundant at natural sites. ‘‘Port species’’ assemblages were composed of (1) small, shortliving species with typical opportunistic characteristics; (2) cosmopolitan large-size taxa, significantly represented both in harbours and in natural habitats; (3) non-indigenous species. Contrarily to the expected lower richness of communities in confined areas, our results demonstrate that the richness of hydroid assemblages in harbours is comparable to that of natural habitats.

The aim of the present study was to determine the epidemiology of jellyfish stings in the Province of Lecce (Italy) in the bathing seasons of years 2007-2011, in order to estimate the presence of these organisms along the coast of the Salento and assess its socio-health implications. The study involved the gathering and processing of data on patients seeking medical treatment at summer first aid centres and hospitals along the coast of the Salento following contact with jellyfish. The analysis of reports showed that in the period 2007-2011 1733 stung bathers sought medical assistance, accounting for 3% of all medical services provided at first aid centres. In addition, jellyfish stings were observed to be the main cause of human pathologies arising from contact with marine organisms. 25.7% of total cases were reported in summer 2007, 22.5% in 2008, 24.7% in 2009, 17.6% in 2010 and 9.5% in 2011. The spatial distribution indicates a greater frequency of stings sustained along the Adriatic coast (65%); this trend is related to wind direction. Most of the injuries were seen in persons aged between 1 and 10. In the majority of cases the symptoms were not severe, being confined to local and cutaneous reactions. In 8.7% of cases however, there were complications, mainly allergic reactions (6.2%). The main drugs used are corticosteroids, locally applied and systemic (46% and 43%, respectively), while non-pharmacological treatments mainly consisted of rinsing with ammonia (74%). In the five-year period under study, an average of 8.1 cases/km of coastline was recorded, ranging from a maximum of 18.4 cases/km along the Adriatic coast to a minimum of 2.6 cases/km on the Lower Ionian, with an estimated cost of the health services provided of about 391,658 Euros. Overall, a slightly decreasing trend of jellyfish stings was observed from 2007 to 2011 along the coasts of Salento. Nevertheless, in the light of the significant economic costs and the socio-health impact reported in this study and given the importance of the bathing tourism in the Salento, there is a need to identify suitable strategies that will guarantee the best response in terms of both prevention and treatment.

Hydroids, one of the dominant components of the zoobenthic communities, share comparable growth patterns with higher plants because of their modular body organization, high potential of asexual reproduction, and phenotypic plasticity. These features, together with the ability to enter dormancy to overcome unfavorable conditions, make hydroids successful organisms adaptable to a wide range of environmental scenarios. Depending on their wide range of shapes and sizes, hydroids form three-dimensional forests at different dimensional scales, establishing both trophic and non-trophic relationships with several other organisms, from virus to vertebrates. Despite numerous researches conducted to study the hydroid ecology, the putative importance of hydroids in structuring zoobenthic communities is underestimated. Here, information available about hydroid ecology is summarized, in order to emphasize the role of hydroids as forest formers, as well as their function in the bentho-pelagic coupling.

Strong gradients in physico-chemical properties between abutting water masses create prominent transition zones in the marine environment. The Strait of Gibraltar forms the well defined boundary between the Mediterranean and Atlantic, and this paper examines spatial variation of hydroid assemblages in this transition zone. Although several studies highlighted the transitional character of the Strait and defined it as an ecotone, the benthic hydroid assemblages did not show differences between the Gulf of Ca´diz and the Alboran Sea. However, there is an asymmetrical influence of the Atlantic waters on the coastal benthic ecosystems of the Alboran Sea, which maintains a more Mediterranean character in the hydroid assemblages of the northern coast, whereas a more Atlantic character was found in the rest of the studied sites. The transition zone between Atlantic and Mediterranean benthic communities could be associated with an Atlantic Influence Zone rather than with the Strait of Gibraltar itself.

The Mediterranean hydrozoan fauna (Siphonophora excluded) comprises 400 species; most (68%) occur in the Atlantic Ocean, 20% are endemic to the Mediterranean, 8% are of Indo-Pacific origin, and 4% are non-classifiable. There are 69 nonindigenous (NIS) species in the basin: 44% of these are casual (recorded just one or very few times), 28% established (widely recorded in the basin), 6% invasive (established NIS that are able rapidly or largely to dissemi- nate away from the area of initial introduction, having a noticeable impact on the recipient community), and 22% questionable (of doubtful taxonomic sta- tus). Entry through the Suez Canal and range expansion through the Gibraltar Strait, often enhanced by ship traffic, appear to be the main processes for recent species introductions, but uncertainties remain for many NIS. Species additions immediately result in larger local or regional species pools, but the newcomers might impact on populations of native species, altering extinction probabilities. A more reliable evaluation of the species pool can be accom- plished by adding new species when they enter the taxonomic record (i.e. the records of any taxon in all types of literature), and by removing species that have not been found for a ‘reasonable’ time (e.g. several decades). Of the 400 non-siphonophoran hydrozoan species known to occur in the Mediterranean Sea, positive records in the last 10 years are available for 156 species (39%), whereas records of the remaining 244 species are older than a decade: 67 spe- cies have not been recorded for 41 years, 13 for 31–30 years, 79 for 21– 30 years, and 85 for 11–20 years.

Stinging jellyfish outbreaks represent a health hazard, causing contact dermatitis and systemic reactions. This study investigated the epidemiology, severity, and treatment protocols of jellyfish stings in a coastal area with high tourist development and frequent stinging jellyfish outbreaks of the central Mediterranean (Salento, Southern Italy), and the associated costs for the Italian National Health Service. In 2007–2011, 1,733 bathers (mostly children and females) sought medical assistance following jellyfish stings, the main cause of human pathologies due to contact with marine organisms. The majority of events were reported in the years 2007–2009, whereas the occurrence of cnidarian jellyfish outbreaks has been increasingly reported in the same area since summer 2010. Most symptoms were limited to local and cutaneous reactions; conversely, 8.7% of cases evoked complications, mainly due to allergic reactions. The main drugs used were corticosteroids, locally applied and systemic (46% and 43%, respectively), and with ammonia (74%) as the main non-pharmacological treatment. The estimated cost of jellyfish-related first-aid services along the Salento coastline over the 5-year period was approximately 400,000 Euros. Therefore the management of jellyfish outbreak phenomena need coordinated research efforts towards a better understanding of underlying ecological mechanisms, together with the adoption of effective prevention policy, mitigation strategies, and appropriate planning of health services at tourist hot spots.

Representatives of gelatinous zooplankton are increasingly reported in large numbers, with more than 1000 species worldwide, including Cnidaria, Ctenophora and Thaliacea, often collectively known as “jellyfish”. • The reasons for increasing jellyfish blooms are probably manifold, ranging from local to global. Climate change and overfishing are global phenomena, and are good candidates as primary drivers of the rise of gelatinous zooplankton, at least in some parts of the ocean. • Current evidence suggests that sea warming is forcing temperate marine biota towards the poles, with tropicalization of temperate marine ecosystems due to community phase shifts. Climate change is also negatively affecting tropical communities, as exemplified by the increasing frequency of coral bleaching events. Gelatinous zooplankton appear to be expanding their distributions, as seen in the Mediterranean Sea with the increased presence of tropical species, likely favoured by both temperature increases and the progressive enlargement of the Suez Canal. • There is no evidence that temperature rises are threatening tropical jellyfish species, as they are with corals, but this might be due to current lack of observations. • Increases in temperature may broaden the reproductive periods of mid-latitude jellyfish, and improve winter survival of tropical species expanding to temperate waters, therefore boosting both alien and native outbreaks. • Increases in temperature at high latitudes might be detrimental for indigenous species, reducing their reproductive outputs. So far, limited increases in temperature at high latitudes do not support the proliferation of warm-water, non-indigenous species. • The resulting patterns should see a stable situation at low and high latitudes, with no tendency to gelatinous plankton blooms, whereas these phenomena should increase at mid-latitudes, but this speculation needs to be substantiated by focused studies.

Gelatinous zooplankton outbreaks have increased globally owing to a number of human-mediated factors, including food web alterations and species introductions. The invasive ctenophore Mnemiopsis leidyi entered the Black Sea in the early 1980s. The invasion was followed by the Azov, Caspian, Baltic and North Seas, and, most recently, the Mediterranean Sea. Previous studies identified two distinct invasion pathways of M. leidyi from its native range in the western Atlantic Ocean to Eurasia. However, the source of newly established populations in the Mediterranean Sea remains unclear. Here we build upon our previous study and investigate sequence variation in both mitochondrial (Cytochrome c Oxidase subunit I) and nuclear (Internal Transcribed Spacer) markers in M. leidyi, encompassing five native and 11 introduced populations, including four from the Mediterranean Sea. Extant genetic diversity in Mediterranean populations (n=8, Na = 10) preclude the occurrence of a severe genetic bottleneck or founder effects in the initial colonizing population. Our mitochondrial and nuclear marker surveys revealed two possible pathways of introduction into Mediterranean Sea. In total, 17 haplotypes and 18 alleles were recovered from all surveyed populations. Haplotype and allelic diversity of Mediterranean populations were comparable to populations from which they were likely drawn. The distribution of genetic diversity and pattern of genetic differentiation suggest initial colonization of the Mediterranean from the Black-Azov Seas (pairwise FST = 0.001–0.028). However, some haplotypes and alleles from the Mediterranean Sea were not detected from the well-sampled Black Sea, although they were found in Gulf of Mexico populations that were also genetically similar to those in the Mediterranean Sea (pairwise FST = 0.010–0.032), raising the possibility of multiple invasion sources. Multiple introductions from a combination of Black Sea and native region sources could be facilitated by intense local and transcontinental shipping activity, respectively.

In recent years, negative impacts of jellyfish blooms (JB) on marine human activities have been increasingly reported. Aquaculture has been affected by jellyfish outbreaks, mostly documented through repeated episodes of farmed salmon mortalities in Northern Europe; however, the valuation of JB consequences on the aquaculture sector still remains poorly quantified. This study aims to provide the first quantitative evaluation effects of JB on finfish aquaculture in the Mediterranean Sea and to investigate the general awareness of JB impacts among Mediterranean aquaculture professional workers. The aquaculture workers' perception about JB was assessed through a structured interview-based survey administered across 21 aquaculture facilities in central and western Mediterranean. The workers' awareness about JB impacts on aquaculture differed among countries. Italian and Spanish fish farmers were better informed about jellyfish proliferations and, together with Tunisian farmers, they all recognized the wide potential consequences of JB on sea bream and sea bass aquaculture. On the contrary, the majority of Maltese respondents considered JB as a non-significant threat to their activity, mostly based on off-shore tuna farming. This study for the first time shows that JB may negatively affect different Mediterranean aquaculture facilities from Tunisia (Sicily Channel) and Spain (Alboran Sea), by increasing farmed fish gill disorders and mortality, clogging net cages, or inflicting painful stings to field operators, with severe economic consequences. Available knowledge calls for the development of coordinated preventive plans, adaptation policies, and mitigation countermeasures across European countries in order to address the JB phenomenon and its impacts on coastal water activities.

In recent years, jellyfish blooms have attracted considerable scientific interest for their potential impacts on human activities and ecosystem functioning, with much attention paid to jellyfish as predators and to gelatinous biomass as a carbon sink. Other than qualitative data and observations, few studies have quantified direct predation of fish on jellyfish to clarify whether they may represent a seasonally abundant food source. Here we estimate predation frequency by the commercially valuable Mediterranean bogue, Boops boops on the mauve stinger jellyfish, Pelagia noctiluca, in the Strait of Messina (NE Sicily). A total of 1054 jellyfish were sampled throughout one year to quantify predation by B. boops from bite marks on partially eaten jellyfish and energy density of the jellyfish. Predation by B. boops in summer was almost twice that in winter, and they selectively fed according to medusa gender and body part. Calorimetric analysis and biochemical composition showed that female jellyfish gonads had significantly higher energy content than male gonads due to more lipids and that gonads had six-fold higher energy content than the somatic tissues due to higher lipid and protein concentrations. Energetically, jellyfish gonads represent a highly rewarding food source, largely available to B. boops throughout spring and summer. During the remainder of the year, when gonads were not very evident, fish predation switched towards less-selective foraging on the somatic gelatinous biomass. P. noctiluca, the most abundant jellyfish species in the Mediterranean Sea and a key planktonic predator, may represent not only a nuisance for human leisure activities and a source of mortality for fish eggs and larvae, but also an important resource for fish species of commercial value, such as B. boops.

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.

Predation occurs when an organism completely or partially consumes its prey. Partial consumption is typical of herbivores but is also common in some marine microbenthic carnivores that feed on colonial organisms. Associations between nudibranch molluscs and colonial hydroids have long been assumed to be simple predator–prey relationships. Here we show that while the aeolid nudibranch Cratena peregrina does prey directly on the hydranths of Eudendrium racemosum, it is stimulated to feed when hydranths have captured and are handling prey, thus ingesting recently captured plankton along with the hydroid polyp such that plankton form at least half of the nudibranch diet. The nudibranch is thus largely planktivorous, facilitated by use of the hydroid for prey capture. At the scale of the colony this combines predation with kleptoparasitism, a type of competition that involves the theft of already-procured items to form a feeding mode that does not fit into existing classifications, which we term kleptopredation. This strategy of subsidized predation helps explain how obligate-feeding nudibranchs obtain sufficient energy for reproduction from an ephemeral food source.

In spite of considerable research effort on the “immortal jellyfish” Turritopsis dohrnii (Weismann, 1883), a comprehensive account including the ontogenetic stages throughout its normal life cycle is still missing. Here, we report the development of the medusa morph, with description of four consecutive stages distinguished by the morphology of the umbrellar apex and the number of marginal tentacles. Medusae reared at two different temperatures (14 and 25°C) showed identical morphological features, but with shorter developmental time at higher temperature. Additional information on the morphology of the polyp stage is also provided. The implications for an easy morphological identification of T. dohrnii medusae from other congeneric species are discussed.

In the last 20–30 years, the temperature of the Mediterranean Sea has increased and global warming is allowing the establishment of tropical-affinity species into more temperate zones. Sessile communities are particularly useful as a baseline for ecological monitoring; however, a lack of historical data series exists for sessile marine organisms without commercial interest. Hydroids are ubiquitous components of the benthic sessile fauna on rocky shores and have been used as bio-indicators of environmental conditions. In this study on the benthic hydroid assemblages of the Chafarinas Islands (Alboran Sea, South-Western Mediterranean), we characterized the hydroid assemblages, identified the bathymetric gradients, and compared them with a previous study carried out in 1991. Hydroid assemblages showed a significant difference both between year and among depths. Furthermore, eight species not present in 1991 were found, including two possible new species and the tropical and subtropical species Sertularia marginata. Due to its strategic position at the entrance of the Mediterranean and the existence of previous data on hydroid assemblages, the Chafarinas Islands are proposed as a possible monitoring point for entrance of Atlantic tropical species into the Mediterranean Sea.

The “stem cells” discipline represents one of the most dynamic areas in biomedicine. While adult marine/aquatic invertebrate stem cell (MISC) biology is of prime research and medical interest, studies on stem cells from organisms outside the classical vertebrate (e.g., human, mouse, and zebrafish) and invertebrate (e.g., Drosophila, Caenorhabditis) models have not been pursued vigorously. Marine/aquatic invertebrates constitute the largest biodiversity and the widest phylogenetic radiation on Earth, from morphologically simple organisms (e.g., sponges, cnidarians), to the more complex mollusks, crustaceans, echinoderms, and protochordates. These organisms contain a kaleidoscope of MISC-types that allow the production of a large number of novel bioactive-molecules, many of which are of significant potential interest for human health. MISCs further participate in aging and regeneration phenomena, including whole-body regeneration. For years, the European MISC-community has been highly fragmented and has established scarce ties with biomedical industries in an attempt to harness MISCs for human welfare. Thus, it is important to (i) consolidate the European community of researchers working on MISCs; (ii) promote and coordinate European research on MISC biology; (iii) stimulate young researchers to embark on research in MISC-biology; (iv) develop, validate, and share novel MISC tools and methodologies; (v) establish the MISC discipline as a forefront interest of biomedical disciplines, including nanobiomedicine; and (vi) establish collaborations with industries to exploit MISCs as sources of bioactive molecules. In order to fill the recognized gaps, the EC-COST Action 16203 “MARISTEM” has recently been launched. At its initial stage, the consortium unites 26 scientists from EC countries, Cooperating countries, and Near Neighbor Countries.

The 2011-2014 European Community project VECTORS (“Vectors of Change in Oceans and Seas-Marine Life, Impact on Economic Sectors”) was an integrated, multidisciplinary European project which aimed to improve our understanding of how environmental anthropogenic drivers are impacting European marine ecosystems now and in the future. VECTORS investigated how these changes may affect marine biodiversity and ecosystem functioning, the range of goods and services provided by the oceans, the resulting socio-economic impacts and some possible future scenarios for mitigation and adaptation.

The planula larva of the hydroid Clava multicornis has a complex nervous system, characterized by the presence of distinct, anteriorly concentrated peptidergic populations of amidated neurons, presumably involved in the detection of environmental stimuli and metamorphic signals. Differently from other hydrozoan larvae, in C. multicornis planulae GLW-positive cells with putative sensory role have a peculiar dome-shaped forefront organization, followed by a belt of RF-positive nerve cells. By immunohistochemistry we investigated the transformation of the peptidergic (GLW-amide and RF-amide) larval neuroanatomy at different stages of metamorphosis and the subsequent development of the primary polyp nervous system. By TUNEL assay, apoptotic nuclei were first identified in the anterior pole of the settled larva, in the same region occupied by GLW-amide positive putative sensory cells. In primary polyps, GLW-amide positive signals first encircled the hypostome area, later extending downwards along the polyp column or upwards over the hypostome dome, whereas RF-amide positive sensory cells initially appeared at the tentacles base to later extend in the tentacles and the polyp column. In spite of the possession of distinct neuroanatomies, different cnidarian planulae may share common developmental mechanisms underlying metamorphosis, including apoptosis and de novo differentiation. Our data confirm the hypothesis that the developmental dynamics of tissue rearrangements may be not uniform across different taxa.

This manuscript deals with the first records of five jellyfish species in the Marmara Sea (Turkey) of previously unrecorded medusozoan species (four hydrozoan taxa, Liriope tetraphylla, Aglaura hemistoma, Solmundella bitentaculata, Neoturris pileata, and one scyphozoan, Paraphyllina ransoni) from plankton collections made in the years 2001-2008. Jellyfish abundances and distribution patterns are reported here, with a discussion about their possible introduction pathways and potential predatory outcomes into the fragile pelagic ecosystem of the Marmara Sea.

This Collective Article presents information on 37 taxa belonging to 6 Phyla and extending from the western Mediterranean to the Levantine Sea. The new records were found in 10 countries as follows: Algeria: first reports on the presence of the fish species Lesueurigobius sanzi, L. friesii, L. suerii and Luvarus imperiali; France: first record of the alien nudibranch Godiva quadricolor; Italy: first record of an adult-sized red emperor snapper Lutjanus sebae from the southern Tyrrhenian Sea; first record of the pantropical rhodophyte Chondria curvilineata and the Lessepsian fish Siganus luridus from southern Sicily; record of a large pregnant female Dusky shark Carcharhinus obscurus off Sicily; Albania: first record of the fish Ruvettus pretiosus, new records of the alien molluscs Conomurex persicus, Bursatella leachii, Dendostrea cf. folium, Fulvia fragilis and Ruditapes philippinarum and additional report of the alien bivalve Pinctada imbricata radiata; Montenegro: first record of the sea slug Thecacera pennigera in the Adriatic Sea; Greece: first record of the invasive calcarean sponge Paraleucilla magna in Greek waters; occupancy estimation of the established cryptogenic rhodophyte Ganonema farinosum, the alien crustacean Percnon gibbesi and the alien fish species Fistularia commersonii, Siganus luridus, and S. rivulatus along the Cretan coastline; first record of the alien mollusc Sticteulimalentiginosa in Greek waters suggesting a westward unintentional expansion of this species; Turkey:photographic evidence of interactions of the monk seal Monachus monachus with sea-cage farms in the Turkish Aegean Sea and first record of the yellow boxfish Ostracion cubicus in the Turkish Mediterranean; Cyprus: first records of the rare speleophilic fish Thorogobius ephippiatus and Grammonus ater in Cyprus, extending the known distribution of the latter Mediterranean endemic species eastwards; first records of the alien fish Kyphosus vaigiensis and the alien crustacean species Macrophthalmus indicusand Carupa tenuipes as well as additional records of the alien echinoderm Diadema setosum and the alien ascidian Symplegma brakenhielmi in the country; Lebanon: first report on the presence of the four alien fish species Cephalopholis taeniops, Equulites popei, Pseudupeneus prayensis and Sphoeroides pachygaster; Egypt: first record of the Lessepsian fish Synchiropus sechellensisin the Egyptian Mediterranean waters.

Thirty-eight nonindigenous marine species (NIS) (macroalgae, sponges, hydrozoans, molluscs, polychaetes, crustaceans, ascidiaceans and fish), are reported from the Apulian coast of Italy. Shipping, aquaculture and migration through the Suez Canal are the main pathways of introduction of the NIS. In Apulian waters, 21% of NIS are occasional, 18% are invasive and 61% are well-established. It is highly probable that more NIS will arrive from warm-water regions, because Mediterranean waters are warming. Furthermore, some of the successful NIS must have the ability to become dormant in order to survive adverse conditions, either seasonal or during long journeys in ballast waters. The identification of NIS depends greatly on the available taxonomic expertise; hence the paucity of taxonomists hinders our knowledge of NIS in our seas. We propose the creation and maintenance of a network of observatories across the Mediterranean to monitor the changes that take place along its coasts.

A bloom of an unknown semaestome jellyfish species was recorded in the North Adriatic Sea from September 2013 to early 2014. Morphological analysis of several specimens showed distinct differences from other known semaestome species in the Mediterranean Sea and unquestionably identified them as belonging to a new pelagiid species within genus Pelagia. The new species is morphologically distinct from P. noctiluca, currently the only recognized valid species in the genus, and from other doubtful Pelagia species recorded from other areas of the world. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal DNA genes corroborate its specific distinction from P. noctiluca and other pelagiid taxa, supporting the monophyly of Pelagiidae. Thus, we describe Pelagia benovici sp. nov. Piraino, Aglieri, Scorrano & Boero.

Over recent decades, man’s expanding infl uence on the oceans has begun to cause change in some regions, including in the Mediterranean Sea. New proliferations of jellyfi sh may be occurring in the Mediterranean Sea, possibly in response to the cumulative effects of some of these anthropogenic impacts. In the Mediterranean Sea, many of these “proliferation events” are due to Pelagia noctiluca , an oceanic scyphozoan that has become very abundant along the coasts. Pelagia noctiluca is usually considered to be the most important jellyfi sh species in the Mediterranean Sea due to its widespread distribution, abundance, and ecological role and also because of its negative interaction with humans. Climatic conditions that favor enhanced reproduction by P. noctiluca and probably also determine optimal conditions for the formation of blooms are characterized by mild winters, low rainfall, high temperature, and high-atmospheric pressure. The Medusa Project in Catalonia aims to understand the spatiotemporal dynamics of the jellyfi sh populations in the NW Mediterranean Sea by undertaking daily sampling during summer (May to September) of 243 beaches, covering more than 500 km of coast. Data on beach strandings along the Spanish Catalan coast revealed that jellyfi sh occur in greatest concentrations along the northern Catalan coast and on beaches located close to marine canyons. The arrival of P. noctiluca to the coast depends fi rstly on the offshore production of jellyfi sh. Oceanographic structures like fronts, which enhance and maintain high levels of biological production and provide ideal conditions for feeding, growth, and reproduction of the jellyfi sh are present in the NW Mediterranean. The weakening of the front results in large numbers of P. noctiluca being driven into the coast by southeast winds. In the NW Mediterranean Sea P. noctiluca exert top-down control over a variety of prey including fi sh eggs and possibly the invasive ctenophore Mnemiopsis leidyi . P. noctiluca is also responsible for the majority of the stings incurred by bathers along the Catalan coast. Finally, we recommend that similar sampling programs should be done elsewhere to better understand changes in the distribution, abundance, and blooming patterns of dangerous jellyfi sh species.

The non-indigenous hydrozoan Clytia hummelincki, recorded for the first time in the Mediterranean Sea in 1996, has now become established on barren grounds where conditions of low diversity, high grazing pressure and low levels of competition occur. The mechanisms of persistence of this species, as well as its population dynamics in this habitat and in species-rich, algae-dominated shallow rocky communities were investigated in situ at four sampling sites in the Northern Ionian Sea from October 2012 to September 2014. Multivariate analyses were conducted to assess the differences in population dynamics of this species in both contrasting habitats. Clytia hummelincki reached peak abundance during summer, with numerous reproductive structures observed in August and September. A remarkable regression period was evident in the cold season, when colonies were largely reduced to dormant tissue in the coenosarc of the hydrorhiza and were often covered by encrusting algae. Both regeneration of colonies from resting hydrorhizae and recruitment of new planulae are involved in the maintenance of the populations. Colonies regrew from hydrorhizae less than half of the time. Population dynamics in sea-urchin barren grounds and algae-dominated communities did not differ significantly, suggesting that populations of this hydrozoan are now well established in the central Mediterranean Sea. This species is no longer confined to low diversity, highly grazed, low competition environments.

Investigations on sexual reproduction of jellyfish are essential to understanding mechanisms and patterns of outbreaks formation. Pelagia noctiluca (Forskål, 1775) (Scyphozoa) is known as the predominant jellyfish species with direct development in Western and Central Mediterranean Sea. In this paper we used integrated morphometric, histological, and biochemical approaches to investigate the annual reproductive biology of P. noctiluca from the Strait of Messina (South Thyrrenian Sea), a key proliferation area for this species due to favourable temperatures and high productivity. From November 2011 to September 2012, P. noctiluca sexual reproduction occurred throughout the year, with two seasonal peaks (autumn, spring) of spawning and embryonic development. Gonads of female P. noctiluca were characterized by a large amount of mature eggs of small size (diameter < 200 mm) during high food availability, whereas fewer, larger eggs (diameter > 200 mm) were detected during low availability of prey. Two morphometric indexes were applied: the Gonad-Somatic Index (GSI, gonadal/somatic tissue dry weight ratio) and Fecundity Index (FI, n eggs mm2 * gonadal dry weight). The FI showed longer spawning periods than the GSI, providing a better causal-mechanistic explanation for the year-round occurrence of P. noctiluca in the Strait of Messina. Protein contents of the gonads changed seasonally, with the highest concentrations during the pre-spawning periods. We suggest that investigations on jellyfish sexual reproduction can provide biological information relevant for understanding mechanisms of jellyfish blooms as well as for the management of coastal zones affected by outbreaks of gelatinous species.

Retinoic acid (RA) is a derivative of vitamin A known to be involved in the regulation of many developmental and physiological processes in chordates. Recently, evidence showing its presence and function in invertebrate deuterost omes and protostomes indicated the early evolutionary origin and conservation of the RA developmental machinery, with a key role also in neural differentiation. Moreover, it is known that retinoids can influence pattern specification in polyps of the hydroid Hydractinia echinata. The planula larvae of the hydrozoan Clava multicornis are characterized by a complex nervous system formed by a frontal neural plexus composed by two distinct peptidergic cell populations with antero-posterior organization: a first, anterior-most GLWamide immunoreactive (GLW-IR) population and an RFamide immunoreactive (RF-IR) cell belt just posterior to the first population. In contrast to most swimming planulae, C. multicornis larvae display a smooth gliding movement on the substrate, characterized by alternate bending of the anterior pole. We tested the effects of RA and of an RA antagonist on C. multicornis development by analyzing the nervous system organization and the photoresponsive behav- ior of larvae exposed to RA during their embryogenesis. After the exposure, the nervous system became completely disorganized, leading to the displacement of RFamide-IR cells. Moreover, RA-treated larvae did not exhibit the typ- ical phototropic behavior of control specimens. Our results suggest that RA can alter the normal development of nervous elements in this hydroid species, supporting the hypothesis that the morphogenetic activity of RA predates the origin of chordates.

The shallow-water hydrozoan Antarctic fauna is still poorly studied, and available knowledge mostly refers to samples gathered by traditional ship-operated gears. By scuba diving in the coastal areas off the Italian Antarctic station "Mario Zucchelli" (Ross Sea, Terra Nova Bay), in the austral summer 2002-2003, a total of 20 hydrozoan species were found, belonging to 10 families and 13 genera. As hypothesized, Anthoathecata (11 species), usually under-represented in collections from indirect sampling gears, are common as also are Leptothecata (9 species). Hydractiniidae and Hydractinia are the dominant family and genus, followed by Haleciidae and Halecium. A new species to science, Halecium exaggeratum sp. nov. is also described. Most species are either endemic to Antarctic waters or restricted to Antarctic/sub-Antarctic areas; only two species have a wider distribution. Material reared in aquaria at the Italian Antarctic Base Mario Zucchelli facilitated knowledge of the life cycle and reproductive biology of several species. In particular, Opercularella belgicae was found to liberate a medusa stage referable to Phialella, and the species is assigned here to that genus, as Phialella belgicae. Also, extraordinary is the complete absence or scant representation of the most typical Antarctic benthic hydroid genera (Antarctoscyphus, Oswaldella, Schizotricha, Staurotheca, and Symplectoscyphus), likely related to the shallow limits of sampling (down to 48 m).

Deep-sea coral assemblages are key components of marine ecosystems that generate habitats for sh and invertebrate communities and act as marine biodiversity hot spots. Because of their life history traits, deep-sea corals are highly vulnerable to human impacts such as shing. They are an indicator of vulnerable marine ecosystems (VMEs), therefore their conservation is essential to preserve marine biodiversity. In the Mediterranean Sea deep-sea coral habitats are associated with commercially important crustaceans, consequently their abundance has dramatically declined due to the e ects of trawling. Marine spatial planning is required to ensure that the conservation of these habitats is achieved. Species distribution models were used to investigate the distribution of two critically endangered octocorals (Funiculina quadrangularis and Isidella elongata) in the central Mediterranean as a function of environmental and sheries variables. Results show that both species exhibit species- speci c habitat preferences and spatial patterns in response to environmental variables, but the impact of trawling on their distribution di ered. In particular F. quadrangularis can overlap with shing activities, whereas I. elongata occurs exclusively where shing is low or absent. This study represents the rst attempt to identify key areas for the protection of soft and compact mud VMEs in the central Mediterranean Sea.

Jellyfish are recorded with increasing frequency and magnitude in many coastal areas and several species display biological features comparable to the most popular Asiatic edible jellyfish. The biochemical and antioxidant properties of wild gelatinous biomasses, in terms of nutritional and nutraceutical values, are still largely unexplored. In this paper, three of the most abundant and commonly recorded jellyfish species (Aurelia sp.1, Cotylorhiza tuberculata and Rhizostoma pulmo) in the Mediterranean Sea were subject to investigation. A sequential enzymatic hydrolysis of jellyfish proteins was set up by pepsin and collagenase treatments of jellyfish samples after aqueous or hydroalcoholic protein extraction. The content and composition of proteins, amino acids, phenolics, and fatty acids of the three species were recorded and compared. Protein content (mainly represented by collagen) up to 40% of jellyfish dry weight were found in two of the three jellyfish species (C. tuberculata and R. pulmo), whereas the presence of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) was significantly higher in the zooxanthellate jellyfish C. tuberculata only. Remarkable antioxidant ability was also recorded from both proteinaceous and non proteinaceous extracts and the hydrolyzed protein fractions in all the three species. The abundance of collagen, peptides and other bioactive molecules make these Mediterranean gelatinous biomasses a largely untapped source of natural compounds of nutraceutical, cosmeceutical and pharmacological interest.

The European Alien Species Information Network (EASIN) aims to facilitate the exploration of alien species information in Europe, and is recognized as the information system supporting European Union Member States in the implementation of the recently published Invasive Alien Species Regulation. In this paper, we present the role and activities of the EASIN Editorial Board (EB), which is responsible for the quality assurance, safeguarding and constant improvement of EASIN. The EB is supported by a web platform that facilitates online discussions about alien species. This platform creates a virtual community by providing a forum-like interface that is moderated by the EB Members but is freely accessible to the scientific community and the general public. It allows all registered users to make comments, raise questions and share experience and expertise on alien species in Europe. Moreover, it provides a means for exchanging opinions and solving disputes in a transparent way. The overall EB activity is commonly agreed upon procedures and standards

The Suez Canal is one of the most important waterways in the world – during the last year 17,148 ships passed through the Canal – reducing emissions, saving time, and operating costs to shippers. The rapid increase in ship size from the “Post-Suezmax” (> 12,000 TEU) to the latest container vessels (> 19,000 TEU) now requires enlargements of port facilities and canals. A project of this magnitude, and with potentially negative environmental outcomes, requires a transparent and scientifically sound “Environmental Impact Assessment” (EIA). An explicit obligation on Parties to the Convention on Biological Diversity (https://www.cbd.int/doc/ legal/cbd-en.pdf) was made to consider transboundary impacts on biodiversity, particularly those associated with invasive non-indigenous species.

The occurrence of the white-spotted Australian jellyfish Phyllorhiza punctata Lendenfeld, 1884, an Indo-Pacific scyphozoan species mainly restricted to the Levantine Basin, is hereby reported for the first time from Maltese waters (western Mediterranean) and from the Ionian coast of Italy. Considerations on possible vectors of introduction of the jellyfish species to this part of the Mediterranean are made.

The rapid expansion of multicellular native and alien species outbreaks in aquatic and terrestrial ecosystems (bioinvasions) may produce significant impacts on bacterial community dynamics and nutrient pathways with major ecological implications. In aquatic ecosystems, bioinvasions may cause adverse effects on the water quality resulting from changes in biological, chemical and physical properties linked to significant transformations of the microbial taxonomic and functional diversity. Here we used an effective and highly sensitive experimental strategy, bypassing the efficiency bottleneck of the traditional bacterial isolation and culturing method, to identify changes of the planktonic microbial community inhabiting a marine coastal lagoon (Varano, Adriatic Sea) under the influence of an outbreak-forming alien jellyfish species. Water samples were collected from two areas that differed in their level of confinement inside in the lagoon and jellyfish densities (W, up to 12.4 medusae m-3; E, up to 0.03 medusae m-3) to conduct a snapshot microbiome analysis by a metagenomic approach. After extraction of the genetic material in the environmental water samples, we deep-sequenced metagenomic amplicons of the V5- V6 region of the 16S rRNA bacterial gene by an Illumina MiSeq platform. Experiments were carried out in triplicates, so six libraries of dual indexed amplicons of 420 bp were successfully sequenced on the MiSeq platform using a 2x250 bp paired-end sequencing strategy. Approximately 7.5 million paired-end reads (i.e. 15 million total reads) were generated, with an average of 2.5 million reads (1.25 M pairs) per sample replicate. The sequence data, analyzed through a novel bioinformatics pipeline (BioMaS), showed that the structure of the resident bacterial community was significantly affected by the occurrence of jellyfish outbreaks. Clear qualitative and quantitative differences were found between the western and eastern areas (characterized by many or few jellyfish), with 84 families, 153 genera and 324 species in the W samples, and 104 families, 199 genera and 331 species in the E samples. Significant differences between the two sampling areas were particularly detected in the occurrence of 16 families, 22 genera and 61 species of microbial taxa. This is the first time that a NGS platform has been used to screen the impact of jellyfish bioinvasions on the aquatic microbiome, providing a preliminary assessment of jellyfish-driven changes of the functional and structural microbial biodiversity.

The mucus produced by many marine organisms is a complex mixture of proteins and polysaccharides forming a weak watery gel. It is essential for vital processes including locomotion, navigation, structural support, heterotrophic feeding and defence against a multitude of environmental stresses, predators, parasites, and pathogens. In the present study we focused on mucus produced by a benthic cnidarian, the sea anemone Actinia equina (Linnaeus, 1758) for preventing burial by excess sedimentation and for protection. We investigated some of the physico-chemical properties of this matrix such as viscosity, osmolarity, electrical conductivity, protein, carbohydrate, and total lipid contents. Some biological activities such as hemolytic, cytotoxic, and antibacterial lysozyme-like activities were also studied. The A. equina mucus is mainly composed by water (96.2% ± 0.3%), whereas its dry weight is made of 24.2% ± 1.3% proteins and 7.8% ± 0.2% carbohydrates, with the smallest and largest components referable to lipids (0.9%) and inorganic matter (67.1%). The A. equina mucus matrix exhibited hemolytic activity on rabbit erythrocytes, cytotoxic activity against the tumor cell line K562 (human erythromyeloblastoid leukemia) and antibacterial lysozyme-like activity. The findings from this study improve the available information on the mucus composition in invertebrates and have implications for future investigations related to exploitation of A. equina and other sea anemones' mucus as a source of bioactive compounds of high pharmaceutical and biotechnological interest.

The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database.        For each species, the following information is reported: description, cnidome, biology, occurrence in Salento, worldwide distribution, and bibliography. Descriptions refer to the benthic hydroid stage and, when present, also to the planktonic medusa stage. The 115 species of Hydrozoa, recorded along the Salento coastline, represent 25% of the Mediterranean Hydrozoa fauna (totaling 461 species), and nearly 3% of 3,702 world's known species covered in a recent monograph. Four species are non-indigenous, three of them with invasive behavior (Clytia hummelincki, Clytia linearis, and Eudendrium carneum), and one species now very common (Eudendrium merulum) in Salento. The complete life cycle of Clytia paulensis (Vanhöffen, 1910) is described for the first time. 

The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database. For each species, the following information is reported: description, cnidome, biology, occurrence in Salento, worldwide distribution, and bibliography. Descriptions refer to the benthic hydroid stage and, when present, also to the planktonic medusa stage. The 115 species of Hydrozoa, recorded along the Salento coastline, represent 25% of the Mediterranean Hydrozoa fauna (totaling 461 species), and nearly 3% of 3,702 world's known species covered in a recent monograph. Four species are non-indigenous, three of them with invasive behavior (Clytia hummelincki, Clytia linearis, and Eudendrium carneum), and one species now very common (Eudendrium merulum) in Salento. The complete life cycle of Clytia paulensis (Vanhöffen, 1910) is described for the first time.

In late autumn and early winter of 2004, two individuals of the Erythrean alien Rhopilema nomadica were sighted at two locations off the Maltese Islands, marking the westernmost records of this species in the Mediterranean Sea. Since only two adult specimens were ever reported from Maltese waters, in the species has yet to establish a reproducing population in the Sicily Channel. The record is considered as yet another hallmark of the warming trend of the Mediterranean Sea.

The early origin and evolutionary radiation of graptolites (Hemichordata : Pterobranchia) is a story told almost entirely in the fossil record, but for four extant species of the genus Rhabdopleura Allman, 1869. Here we report the discovery of a fifth species, Rhabdopleura recondita, sp. nov., at a depth range of 2–70m from the Adriatic and Ionian Seas, always associated with bryozoans in coralligenous habitats. This is the first pterobranch record in Italian waters, and the second in the Mediterranean Sea. The new species is characterised by: (1) tubaria with smooth creeping tubes adherent to the inside of empty bryozoan zooecia; (2) erect outer tubes with a graptolite, fusellar-like organisation; and (3) zooids that extend from a black stolon, which is free from the creeping tube. Each of the paired feeding arms has two rows of tentacles that do not extend to the arm tip. The distal ends of the arms, the collar and the cephalic shield are replete with black granules. Phylogenetic analyses of individual and concatenated gene sequences of mitochondrial 16S rDNA and nuclear 18S rDNA support the validity of R. recondita as a new species. Finally, we discuss the global biogeographic and habitat distributions of the extant Rhabdopleura representatives.

Molecular analyses have led to an increased knowledge of the number and distribution of morphologically cryptic species in the world's oceans and, concomitantly, to the identification of non-indigenous species (NIS). Traditional taxonomy and accurate delimitation of species’ life histories and autecology lag far behind, however, even for the most widely distributed taxa, such as the moon jellyfish Aurelia (Cnidaria, Scyphozoa) species complex. Here we analysed mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal RNA (28S) gene sequences to assign polyps, ephyrae, and medusae collected in the Mediterranean Sea to different phylogenetic species. We find evidence for three Aurelia species, none of which are referable to the type species of the genus, Aurelia aurita (Linnaeus, 1758), and describe the anatomical, morphometric, and developmental variation within and between them. We identify Aurelia coerulea von Lendenfeld, 1884 and Aurelia solida Browne, 1905 as established non-indigenous species in the Mediterranean Sea. We describe Aurelia relicta sp. nov., an endemic species currently unique to a population in the marine lake of Mljet (Croatia). These results demonstrate the usefulness of integrative approaches in resolving taxonomic uncertainty surrounding cryptic species complexes, identifying patterns of marine biodiversity, and recognizing non-indigenous species in marine ecosystems.

Human use of the European marine environment is increasing and diversifying. This is creating new mechanisms for human induced-changes in marine life which need to be understood and quantified as well as the impact of these changes on ecosystems, their structures (e.g. biodiversity) and functioning (e.g. productivity), and the social and economic consequences that arise. The current and emerging pressures are multiple and interacting, arising, for example, from transport, platforms for renewable and nonrenewable energy, exploitation of living and non-living resources, agricultural and industrial discharges, together with wider environmental changes (including climate change). Anticipating the future consequences of these pressures and vectors of change for marine life and of adaptation and mitigation measures (such as the introduction of new technologies and structures, new ballast water practices, ocean and offshore wind energy devices and new fishing strategies) is a prerequisite to the development and implementation of strategies, policies and regulations to manage the marine environment, such as the IMO Convention on ballast water management and the EU Maritime Policy and Marine Strategy Framework Directive.