Marco Bertolino

Characteristics of the mesophotic megabenthic assemblages of the Vercelli Seamount (North Tyrrhenian Sea)

The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount) is described using Remotely Operated Vehicle (ROV) video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i) the top shows a dense covering of the kelp Laminaria rodriguezii; (ii) the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii) the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface) with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.

Deep Coral Oases in the South Tyrrhenian Sea

A Mediterranean “roche du large” ecosystem, represented by four rocky shoals, located a few miles apart on a muddy bottom at 70–130 m depth in the gulf of St. Eufemia (Calabria, South Tyrrhenian Sea), was studied by means of Remotely Operated Vehicle (ROV) photo imaging. The shoals host highly diversified coral communities, mainly composed of arborescent colonies of gorgonians (Callogorgia verticillata, Paramuricea clavata, Paramuricea macrospina, Bebryce mollis, Villogorgia bebrycoides, Corallium rubrum, and Leptogorgia sarmentosa), and antipatharians (Antipathella subpinnata, Antipathes dichotoma and Parantipathes larix). The coral colonies reach high densities (up to ca. 17 colonies m−2) and large sizes, such as the over 1.5 m wide antipatharian colonies. We hypothesized that the abundance and composition of the coral assemblages differed significantly among the rocky shoals and with respect to the surrounding soft bottoms. Various environmental variables were tested as possible explanatory factors of the observed differences. Moreover, due to their off-coast localization, we report here that these unique ecosystems are potentially subjected to a strong pressure from the local fishing activities, which were tentatively characterized. The recorded coral β-diversity among the shoals supports the hypothesis that these habitats behave like small oases of hard substrata interspersed in a muddy bottom. Because of their intrinsic beauty and rarity and their biological and ecological value, we stress the need of specific actions aimed at the urgent protection of these oases of biodiversity.

Temporal variations in growth and reproduction of Tedania anhelans and Chondrosia reniformis in the North Adriatic Sea

Most works concerning growth and reproduction of Mediterranean sponges have been performed in the oligotrophic western Mediterranean while little is known about sponge dynamics in the North-western Adriatic Sea, a basin characterized by low winter temperature and eutrophy. In order to deepen our understanding of sponges in the North Adriatic Sea and verify how its peculiar trophic and physical conditions affect sponge life cycles, temporal trend of sponge cover (%) and reproductive timing of Chondrosia reniformis and Tedania (Tedania) anhelans were studied over a 1-year period looking for a possible relation with variations of temperature or food availability. In C. reniformis, although little variations of sponge cover were evidenced around the year, the number of individuals and their size increase during spring. Asexual reproduction, via drop-like propagules, mainly occurs in spring and summer, while sexual reproduction is characterized by a maximum number of oocytes in August. T. anhelans progressively grows from spring to summer and develops propagules on its surface that reach their maximum size in July. In autumn, the sponge undergoes a process of progressive shrinkage and almost disappears in winter when temperature reaches 7–8°C. Larvae occur during summer. In the North Adriatic Sea sponges have larger sizes, higher density and a wider period of oocytes production compared with the same species from the Mediterranean Sea, suggesting these differences could be due to high food availability characterizing the eutrophic Adriatic basin. On the contrary, the sharp water temperature variations and the very low winter temperature, 5–6°C lower than what has been reported for the Mediterranean Sea, regulate temporal variations in abundance and cause the disappearance of thermophile species during winter.

Diversity of Porifera in the Mediterranean coralligenous accretions, with description of a new species

Abstract Temperate reefs, built by multilayers of encrusting algae accumulated during hundreds to thousands of years, represent one of the most important habitats of the Mediterranean Sea. These bioconstructions are known as “coralligenous” and their spatial complexity allows the formation of heterogeneous microhabitats offering opportunities for a large number of small cryptic species hardly ever considered. Although sponges are the dominant animal taxon in the coralligenous rims with both insinuating and perforating species, this group is until now poorly known. Aim of this work is to develop a reference baseline about the taxonomic knowledge of sponges and, considering their high level of phenotypic plasticity, evaluate the importance of coralligenous accretions as a pocket for biodiversity conservation. Collecting samples in four sites along the coast of the Ligurian Sea, we recorded 133 sponge taxa (115 of them identified at species level and 18 at genus level). One species, Eurypon gracilis is new for science; three species, Paratimea oxeata, Clathria (Microciona) haplotoxa and Eurypon denisae are new records for the Italian sponge fauna, eleven species are new findings for the Ligurian Sea. Moreover, seventeen species have not been recorded before from the coralligenous community. The obtained data, together with an extensive review of the existing literature, increase to 273 the number of sponge species associated with the coralligenous concretions and confirm that this habitat is an extraordinary reservoir of biodiversity still largely unexplored, not only taxonomically, but also as to peculiar adaptations and life histories.

Porifera from the Argentine Sea: Diversity in Patagonian scallop beds

Porifera are a frequently collected taxon in the invertebrate by‐catch of the Patagonian scallop Zygochlamys patagonica (King & Broderip 1832) fishery. In order to prevent the destruction of the exploited environments in the Argentine Sea, it is important to know in detail the taxonomic composition of the benthic assemblages. We present here the first study on the sponge assemblage associated with the mollusc species exploited. Thirteen species of Demospongiae (four of which are new records for the Argentine Sea) have been identified, confirming the importance of this phylum as a major component of the scallop bed community.

Epibiotic demosponges on the Antarctic scallop Adamussium colbecki (Smith, 1902) and the cidaroid urchins Ctenocidaris perrieri Koehler, 1912 in the nearshore habitats of the Victoria Land, Ross Sea, Antarctica

The importance of epibiosis in Antarctic benthic communities is highlighted here considering the specific diversity of sponges living on shells of the scallop Adamussium colbecki and on spines of the cidaroid urchin Ctenocidaris perrieri. Scallops are from three different areas along the Victoria Land [Tethys Bay (TB), New Harbour (NH), Dunlop Island (DI)], while cidaroid urchins are from NH but not present in the two other stations. Homaxinella balfourensis is the commonest species both on the scallops and cidaroid urchins. Other common species on scallops are Myxilla (Myxilla) asigmata, Lissodendoryx (Ectyodoryx) nobilis and Iophon unicorne at NH, Iophon unicorne at DI, and Iophon radiatum, Haliclona sp. 1, Iophon unicorne and Lissodendoryx (Ectyodoryx) nobilis at TB. The highest number of sponge species we found on a single scallop was ten and the sample was collected at NH. On the spines of C. perrieri, Isodictya erinacea, Iophon unicorne and Haliclona (Rhizoniera) dancoi are present too. A. colbecki and C. perrieri, generally living on soft bottoms, represent important substrata for several sponge species. In this way, sponges may increase their dispersal exploiting valves and spines as stepping stones.

Boring and cryptic sponges in stylasterids (Cnidaria: Hydrozoa)

Abstract The hydroids belonging to the family Stylasteridae are considered habitat-forming species due to their rigid and branched calcareous skeleton, producing structurally complex habitats which support a high taxonomic diversity of associated fauna. Numerous organisms, such as gastropods, polychaetes, barnacles and other invertebrates, were found in association with dead or living colonies of stylasterids. No specific studies have previously been dedicated to the diversity of sponges in association with these corals. In this study 15 sponge species were found in the coenosteum of Distichopora spp. (ten boring and five insinuating species) and one boring species was associated with Stylaster sp. In Distichopora species the sponges were mainly localized into the dead basal portion of the colonies that is overgrown by algae or bryozoans. Only Aka labyrinthica was found inside the skeleton of the living portion of the colonies, being able to compete with the coenosteal stolon network that pervades the carbonatic skeleton. Nevertheless, in Distichopora spp. colonies no coral reaction to the sponge colonisation was observed. The basal portions of the Stylaster sp. colonies, enveloped by the massive specimens of Spheciospongia cf. solida, were completely demolished by the boring activity of the sponge, while the apical portions were alive. The sponge incorporated the coral skeleton and its tissue penetrated into the coral through the coenosteal pores. Stylaster sp. presented a reaction to prevent the penetration of the sponge: hydranths were regressed and calcium carbonate septa were formed, in order to close the gastropores of the coral, indicating a wide plasticity and quick mineralization of the coenosteum.

Posidonia oceanica meadows as sponge spicule traps

Abstract A quantitative study on the sponge spicules present in a series of horizontal core samples, taken at different levels, from a 1.5 m thick living matte within the Posidonia oceanica meadow of Prelo Bay (Eastern Ligurian Sea), has been performed. Sponge spicule amounts were evaluated by microscopical and chemical analyses. From the superficial samples the spicule number decreased until 60–80 cm depth to increase progressively until the deepest studied layer, 140 cm depth. The same results were obtained from the trend of spicule volume and biogenic silica tested by chemical analysis. Among the recognisable spicule types, the most common are oxeas, followed by tylostyles, achantostyles and strongyles. However, oxeas, tylostyles and achantostyles showed the same trend of the entire spicule population, whereas strongyles had an opposite trend with a maximum value at the 80–100 cm depth. According to the hypothesis that the amount of spicules in the sediment is proportional or at least related to the sponge biomass existing in the surrounding area, our data suggest that the sponge assemblage of Prelo Bay should not have been constant in the past 100–200 years. Our hypothesis is that the rapid urban and industrial development that occurred along the Ligurian coast after the Second World War, particularly in the 1960s, had an important impact on the sponge assemblages of the area.

A new species of Triptolemma (Porifera: Pachastrellidae) from the Pacific Ocean with a revision of the genus

A new species, T. strongylata sp. nov. is described on the basis of material collected from the Pacific Ocean. The new species is characterized by the presence of sinuous strongyles. Moreover the incomplete description of T. simplex (Sara, 1959 ) is implemented on the basis of new abundant material allowing, for the first time, the complete description of the skeleton of a Triptolemma species and the detecting of the presence of monaxonic spicules in the spicular complement of the genus. The skeleton is composed of a thick crust of disorderly arranged mesotriaenes and scattered microscleres, supported by diverging spicule tracts formed by oxeas towards the surface. Both species were recorded associated to boring sponges (Spiroxya and Cliona) in excavations of the calcareous scleraxis of precious corals or in organogenic concretions. In the cavities where the tissue of Triptolemma was recorded the wall of the excavation partially lost its typical pattern characterized by ovoid scars and became irregularly eroded. Our hypothesis is that Triptolemma insinuates inside the erosions produced by other sponges and it is able to enlarge them by an etching mechanism based on chemical dissolution only.

A massive update of non-indigenous species records in Mediterranean marinas

The Mediterranean Sea is home to over 2/3 of the world’s charter boat traffic and hosts an estimated 1.5 million recreational boats. Studies elsewhere have demonstrated marinas as important hubs for the stepping-stone transfer of non-indigenous species (NIS), but these unique anthropogenic, and typically artificial habitats have largely gone overlooked in the Mediterranean as sources of NIS hot-spots. From April 2015 to November 2016, 34 marinas were sampled across the following Mediterranean countries: Spain, France, Italy, Malta, Greece, Turkey and Cyprus to investigate the NIS presence and richness in the specialized hard substrate material of these marina habitats. All macroinvertebrate taxa were collected and identified. Additionally, fouling samples were collected from approximately 600 boat-hulls from 25 of these marinas to determine if boats host diverse NIS not present in the marina. Here, we present data revealing that Mediterranean marinas indeed act as major hubs for the transfer of marine NIS, and we also provide evidence that recreational boats act as effective vectors of spread. From this wide-ranging geographical study, we report here numerous new NIS records at the basin, subregional, country and locality level. At the basin level, we report three NIS new to the Mediterranean Sea (Achelia sawayai sensu lato, Aorides longimerus, Cymodoce aff. fuscina), and the re-appearance of two NIS previously known but currently considered extinct in the Mediterranean (Bemlos leptocheirus, Saccostrea glomerata). We also compellingly update the distributions of many NIS in the Mediterranean Sea showing some recent spreading; we provide details for 11 new subregional records for NIS (Watersipora arcuata, Hydroides brachyacantha sensu lato and Saccostrea glomerata now present in the Western Mediterranean; Symplegma brakenhielmi, Stenothoe georgiana, Spirobranchus tertaceros sensu lato, Dendostrea folium sensu lato and Parasmittina egyptiaca now present in the Central Mediterranean, and W. arcuata, Bemlos leptocheirus and Dyspanopeus sayi in the Eastern Mediterranean). We also report 51 new NIS country records from recreational marinas: 12 for Malta, 10 for Cyprus, nine for Greece, six for Spain and France, five for Turkey and three for Italy, representing 32 species. Finally, we report 20 new NIS records (representing 17 species) found on recreational boat-hulls (mobile habitats), not yet found in the same marina, or in most cases, even the country. For each new NIS record, their native origin and global and Mediterranean distributions are provided, along with details of the new record. Additionally, taxonomic characters used for identification and photos of the specimens are also provided. These new NIS records should now be added to the relevant NIS databases compiled by several entities. Records of uncertain identity are also discussed, to assess the probability of valid non-indigenous status.