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The continuous increase of CO2 emissions in the atmosphere due to anthropogenic activities is one of the most important factors that contribute to Climate Change and generates the phenomenon known as Ocean Acidification (OA). Research conducted at the CO2 vents of Castello Aragonese (Ischia, Italy), which represents a natural laboratory for the study of OA, demonstrated that some organisms, such as polychaetes, thrive under acidified conditions through different adaptation mechanisms. Some functional and ecological traits promoting tolerance to acidification in these organisms have been identified, while the molecular and physiological mechanisms underlying acclimatisation or genetic adaptation are still largely unknown. Therefore, in this study we investigated epigenetic traits, as histone acetylation and methylation, in Platynereis spp. individuals coming from the Castello vent, and from a nearby control site, in two different periods of the year (November-June). Untargeted metabolomics analysis was also carried out in specimens from the two sites. We found a different profile of acetylation of H2B histone in the control site compared to the vent as a function of the sampling period. Metabolomic analysis showed clear separation in the pattern of metabolites in polychaetes from the control site with respect to those from the Castello vent. Specifically, a significant reduction of lipid/sterols and nucleosides was measured in polychaetes from the vent. Overall results contribute to better understand the potential metabolic pathways involved in the tolerance to OA.

Ocean acidification may impact ecosystems reliant on calcifying organisms, potentially reducing thesocioeconomic benefits these habitats provide. This study investigates the response of growth and skeletalproperties of the non-zooxanthellate stony coral Astroides calycularis living in naturally acidified seawater ata Mediterranean CO2 vent (Ischia, Italy). Unexpectedly, contrasting patterns of calcification were found atpolyp and colony levels. Polyp linear extension rate, bulk skeletal density and net calcification rate increasedwith acidification (i.e., skeletal porosity decreased). At the colony level, a decrease of net calcification ratewas observed in acidified conditions, with colonies that extended less, were smaller, and were composed byfewer polyps, thus partitioning the available energy among less polyps. As a result, the single polyps had ahigher amount of resources available for calcification than in control conditions, and all their growthparameters had higher values. This unforeseen pattern of response to acidification was observed in this studyfor the first time, and contrasts with what previously observed in the Mediterranean solitary coralBalanophyllia europaea,whose polyps invest the calcification resources in linear extension rate to reach thesize at sexual maturity at the expenses of skeletal resistance (i.e. bulk skeletal density). In the colonial A.calycularis asexual reproduction is possible and corals may invest more on skeletal resistance without theurge to reach sexual maturity.

Ocean Acidification (OA) is predicted to have profound impacts on marine ecosystems because carbonate ions are an essential substrate for the biomineralization of shells and skeletons of calcifying marine organisms, from phytoplankton and corals to fishes1,2,3. Volcanic CO2 vent systems, where seawater is naturally acidified, offer a unique opportunity to investigate the response of benthic organisms and habitats to OA. The Ischia Island (Tyrrhenian Sea, Italy) offers a natural laboratory for OA studies, allowing us to investigate how a suite of habitats and species responds to acidification. A. calycularis is a Mediterranean endemic azooxanthellate coral. It is long-lived species and commonly found in dim light shallow rocky habitats of the south-western Mediterranean Sea4. It broods its larvae5 and thus has relatively low dispersal capacities and high potential for local adaptation. This coral is reported as vulnerable in the IUCN red list6. There is one population of A. calycularis that naturally occurs in a semi-submersed cave (Grotta del Mago) affected by CO2 venting, where is highly abundant (70% cover at 1 m depth). Here, we assess population structure and the skeletal characteristics of A. calycularis originating from different sites (naturally acidified and ambient pH sites) along the coast of Ischia Island . We hypothesize that the population thriving under naturally acidified conditions shows higher population dynamics and differences in biomineralization process than the populations studied from other reference sites with ambient pH.Colonies in the Grotta del Mago have encrusting morphology, with smaller size and consequent, lower weight and lower number of polyps compared to conspecifics from sites at normal pH conditions. With increasing acidification (lower pH), the skeletal porosity decreased while the bulk and micro- density increased. Given the reduced calcification rate that may be expected in acidified waters, the observed increase in skeletal density may be counterbalanced by a strong decrease in linear extension rate.

Polychaete worms are known to thrive in extreme environmental conditions, however little is known about how polychaete species will respond to major climatic stressors, such as ocean acidification. Here, we examined the distribution of Fabriciidae (Annelida, Sabellida) species along a gradient of ocean acidification, caused by carbon dioxide (CO2) vent emissions in a shallow, coastal system off the island of Ischia (Tyrrhenian Sea, Italy). A total of 265 specimens of Fabriciidae, representing six species from five genera, were collected along the gradient. Most of the species were found across the entire CO2 gradient, suggesting polychaetes may have a high tolerance for ocean acidification in the future. Two of the species were new to science, and two of the genera were previously unrecorded in the Mediterranean. A full description of the new species Brifacia aragonensis sp. nov. and Parafabricia mazzellae sp. nov. is given, both of which were most abundant in the most acidified areas (pH 6.6-7.2). The geographical distribution and ecology of the new taxa, as well as of the other fabriciid species collected, is discussed. Taxonomic keys to identify the Fabriciidae species currently recorded in the Mediterranean Sea are also provided.

In polar waters, microalgal communities associated with macroalgae exhibit rates of primary production comparable or even higher than those of phytoplanktonic ones. These benthic communities are mainly represented by diatoms. Despite to their crucial ecological role, the biodiversity of Antarctic epiphytic diatoms is poorly studied and greatly underestimated. In the present study, the diversity of epiphytic diatom communities from coastal waters of Terra Nova Bay was investigated and described for the first time. Samplings were made during the 8 Italian Antarctic expeditions in the space of 15 years. Thalli of Iridaea cordata, Phyllophora antarctica and Plocamium cartilagineum were collected during the austral summer. Collections were made from different depths at 5 sampling sites. Taxonomical identification and counting of diatom cells has been carried out by scanning electron microscope. According to our results biomass appears to be inversely related to the diversity. The diatom community composition varied depending on the sampling site as well as on the morphology of the macroalgal host. Some differences could be observed along a depth gradient. In terms of growth form in most cases adnate (e.g. Cocconeis, Amphora) and mobile forms (e.g. Navicula, Nitzschia) dominated. Erect diatom taxa tended to be associated with animal macrofouling species.

Sabella spallanzanii (Gmelin) is one of the best known and widely distributed Mediterranean polychaetes, but available data on its general biology has been inferred mostly from populations recently introduced to Australia. In the present paper, data on gametogenesis and larval development of a Mediterranean population from the Gulf of Taranto (Ionian Sea, Italy) are reported. Histological and electron microscopical analysis of gametogenesis showed that oogenesis, a long process beginning soon after spawning in February, is of extraovarian type. By contrast spermatogenesis is a very fast process lasting from September to December, when the coelomic cavity is completely packed with mature gametes and almost devoid of coelomocytes. During the period of spawning, some experiments of in vitro fertilisation were performed, always without success, while some of the collected females naturally spawned fertilised eggs (100%). Particularly interesting was the discovery of a small percentage of eggs which appeared fertilised but unspawned within the coelomic cavity of female. Investigation of the S. spallanzanii life cycle, from the naturally spawned fertilised eggs to embryonic and juvenile stages, was performed by daily microscopical observations and by SEM. Despite the presence of large eggs giving rise to a lecithotrophic larva, a long pelagic phase was observed, the longest found among Sabellidae. The larval development pattern is also described. Settlement began after about 2 weeks; metamorphosis occurred 10 d after settlement, when mucus was secreted abundantly and an external tube was formed. The long larval pelagic period and the development pattern, suggesting a high potential for dispersal, support both the introduction and invasive behaviour of the species in Australian waters.

WOS: 000288831000015, The state-of-art on alien species in the Mediterranean Sea is presented, making distinctions among the four subregions defined in the EU Marine Strategy Framework Directive: (i) the Western Mediterranean Sea (WMED); (ii) the Central Mediterranean Sea (CMED); (iii) the Adriatic Sea (ADRIA); and (iv) the Eastern Mediterranean Sea (EMED). The updated checklist (December 2010) of marine alien species within each subregion, along with their acclimatization status and origin, is provided. A total of 955 alien species is known in the Mediterranean, the vast majority of them having being introduced in the EMED (718), less in the WMED (328) and CMED (267) and least in the Adriatic (171). Of these, 535 species (56%) are established in at least one area. Despite the collective effort of experts who attempted in this work, the number of introduced species remains probably underestimated. Excluding microalgae, for which knowledge is still insufficient, aliens have increased the total species richness of the Mediterranean Sea by 5.9%. This figure should not be directly read as an indication of higher biodiversity, as spreading of so many aliens within the basin is possibly causing biotic homogenization. Thermophilic species, i.e. Indo-Pacific, Indian Ocean, Red Sea, Tropical Atlantic, Tropical Pacific, and circum(sub)tropical, account for 88.4% of the introduced species in the EMED, 72.8% in the CMED, 59.3% in the WMED and 56.1% in the Adriatic. Cold water species, i.e. circumboreal, N Atlantic, and N Pacific, make up a small percentage of the introduced species, ranging between 4.2% and 21.6% and being more numerous in the Adriatic and less so in the EMED. Species that are classified as invasive or potentially invasive are 134 in the whole of the Mediterranean: 108 are present in the EMED, 75 in the CMED, 53 in the Adriatic and 64 in the WMED. The WMED hosts most invasive macrophytes, whereas the EMED has the lion's share in polychaetes, crustaceans, molluscs and fish., SEBI2010 - Streamlining European 2010 Biodiversity Indicators Expert Group 5; EUEuropean Union (EU) [036949]; Italian Ministry for the Environment, The work was initiated under the auspices of the SEBI2010 - Streamlining European 2010 Biodiversity Indicators Expert Group 5: Numbers and costs of invasive alien species.; Further research on the distribution of alien species in the Mediterranean Sea has been carried out in the frame of the Integrated Project 'SESAME' (Southern European Seas: Assessing and Modelling Ecosystem changes: Project no: 036949) funded by the EU [A. Zenetos, I. Siokou and N. Streftaris] and in the frame of the research project The impacts of biological invasions and climate change on the biodiversity of the Mediterranean Sea' (C.N. Bianchi and C. Morri), an Italy-Israel co-operation funded by the Italian Ministry for the Environment. Special thanks are due to C. Salas Casanova and A. Logan whose constructive criticism and suggestions have improved the manuscript.

Checklist delle specie degli anellidi policheti della fauna Italiana

Observations on the reproductive features are provided for three species of Eunicidae (Lysidice ninetta Audouin and Milne Edwards, Lysidice collaris Grube and Nematonereis unicornis (Grube)). They all occur in Posidonia oceanica meadows as borers in the sheaths. The material examined was collected during several studies on P. oceanica meadows conducted at various times of the year and in different years along the coasts of Sardinia and the Ischia islands (Tyrrhenian Sea), and Otranto (Southern Adriatic Sea). All individuals of the three species were measured (width 3rd chaetiger, diameter of eyes), and checked for presence of gametes. In each of the females recognized, egg diameter was measured. To integrate the observations, living specimens were collected in March 2003 and reared in the laboratory until August 2003 to check for gamete maturation; mature males were fixed for analysis of the structure of the spermatozoa by transmission electron microscopy (TEM). All three species studied are gonochoric. For both species of Lysidice gametes occurred in individuals with a width greater than 0.8 mm. The overall scarcity of mature males and females observed with respect to the total number of specimens collected is probably due to the dimensional constraint exerted by the sheaths. In Lysidice spp. specimens with small developing oocytes were observed in January-February and reached their maximum diameter between June and August (157 µm). Gametes were located mainly in the posterior part of the body, and an enlargement of the eyes (almost doubled in size) characterized mature specimens close to spawning. N. unicornis is a smaller species, and it is less frequent in Posidonia sheaths than Lysidice spp.; individuals with gametes had a width greater than 0.55 mm. A few mature specimens were observed between March and May with a maximum egg diameter of about 155 µm. In this species maturation of the gametes is coupled with a huge enlargement of the eyes (ten-times larger than in immature individuals), while the posterior part of the body is swollen and full of mature gametes, indicating reproduction by schizogamy. Analysis of mature spermatozoa of the three eunicids revealed a similar morphology, which is that of an “ect-aquasperm” type, typical of many free-spawning species with external fertilization. The nucleus is round and globose (2.5 µm diameter) and the acrosome, slightly different among the three species, has the general shape of a truncate sub-cone., Se discuten algunas caracteristicas generales de la biología de la reproducción de tres especies de poliquetos Eunicidae (Lysidice ninetta Audouin and Milne- Edwards, Lysidice collaris Grube y Nematonereis unicornis (Grube)). Estas especies fueron obtenidas en praderas de Posidonia oceánica, en donde viven asociadas a las escamas de las hojas. El material examinado fue recolectado en diferentes anos y en praderas de P. oceánica distribuidas en la costa de Cerdeña, de la isla de Ischia (Mar Tirreno), y de Otranto (Mar Adriatico Sur). Todos los individuos fueron medidos (anchura del tercer segmento, diámetro de los ojos), y analizados para observar en ellos la presencia de los gametos. En cada hembra se midió el diámetro de los huevos. El desarrollo de otros individuos fue observado en el laboratorio desde Marzo a Agosto 2003 con la finalidad de estudiar la maduración de los gametos. Los machos maduros fueron fijados para el análisis de la ultra-estructura de los espermatozoos al Microscopio Electrónico. Las tres especies estudiadas son gonocóricas (sexos separados). Para las dos especies del genero Lysidice las hembras con huevos siempre se presentaron en individuos superiores en anchura a 0,8 mm. La escasez de hembras y machos maduros en relación al total de individuos está probablemente relacionado con las limitaciones que suponen las dimensiones y espesor de las escamas de Posidonia. Individuos de Lysidice spp. con huevos pequeños en desarrollo se observaron desde Enero-Febrero; los oocitos alcanzaron el máximo diámetro en Junio y Agosto (157 μm). Los gametos se localizaron preferentemente en la parte posterior del cuerpo, y cuando los individuos alcanzaron la madurez, sus ojos se hicieron más anchos (casi el doble en su diámetro). N. unicornis es una especie más pequeña, y menos frecuente en las escamas de Posidonia que Lysidice spp. Los individuos con gametos presentan anchuras superiores a 0,55 mm. Algunos individuos maduros fue observado desde Marzo a Mayo, con diámetros máximos de los huevos de casi 155 μm. En esta especie la madurez se relaciona con un enorme aumento del diámetro de los ojos (diez veces mas anchos que en individuos inmaduros), y en la dilatación de la parte posterior del cuerpo llena de gametos maduros; esta característica indica una reprodución de tipo eschizogámico. La ultra-estructura de los espermatozoos maduros es muy similares en las tres especies de Eunicidae, de tipo”ect-aquasperm”, típicas des especies con fecundación externa. El núcleo (2,5 μm en diámetro) es redondo y globular, y el acrosoma, que es un poco diferente entre las especies, es de forma general en cono truncado.

Barnich, R., Fiege, D., Micaletto, G., Gambi, M. C. (2006): Redescription of Harmothoe spinosa Kinberg, 1856 (Polychaeta: Polynoidae) and related species from Subantarctic and Antarctic waters, with the erection of a new genus. Journal of Natural History 40 (1-2): 33-75, DOI: 10.1080/00222930500445044, URL: http://dx.doi.org/10.1080/00222930500445044