Maurizio Pansini

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.

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.

Deep sponge communities of the Gulf of St Eufemia (Calabria, southern Tyrrhenian Sea), with description of two new species

Recently, the rich coral communities of the so called roche du large biocoenose of the Gulf of St Eufemia (southern Tyrrhenian Sea) between 90 and 130 m deep, have been described thanks to remotely operated vehicle (ROV) imaging. This preliminary survey evidenced the massive presence of a well-diversified sponge community living among the coral colonies. This work aims at giving an ecological overview of some of the dominant species of this environment, together with a taxonomic part including the description of new species: Topsentia calabrisellae sp. nov. and Haliclona (Soestella) fimbriata sp. nov. The silted, rocky outcrops of the Gulf of St Eufemia facilitate the settling mainly of massive sponges with erect habit which may also avoid sedimentation by growing on the coral colonies. On the other hand, the site Capo Vaticano, located at the southern boundary of the gulf, characterized by rocky boulders exposed to strong currents and completely devoid of corals, is inhabited by a poor megabenthic community, dominated by patches of massive sponges, such as Topsentia vaceleti , a species of recent description whose aspect in the field was still unknown. In the entire investigated area 19 species have been photographed (often for the first time in vivo ), collected and identified, but the real sponge diversity is certainly under-estimated due to the difficulty of collecting all the sighted specimens through the ROV grabber. Similarly to the coral component, sponges also respond to the same environmental constraints by growing in heterogeneous patches or by showing different morphologies mainly associated with current and sedimentation conditions.

Long-term turnover of the sponge fauna in Faro Lake (North-East Sicily, Mediterranean Sea)

Abstract The paper focuses on the long-term taxonomic composition and distribution of the shallow-water sponge fauna from the meromictic–anchialine coastal basin Faro Lake (Southern Italy), comparing recent qualitative field data with literature data over a 50-year period. The Faro Lake shallow water currently hosts 24 conspicuous species of Porifera belonging to 21 genera, 18 families, eight orders, three subclasses and two classes, i.e. Demospongiae (23) and Calcarea (one). The comparison between the present and past status of the sponge fauna showed a high turnover, with 15 new colonizers and only nine persistent species. Thirteen species reported in the literature are missing, suggesting the occurrence of remarkable changes in the faunal composition during the last 50 years. The analysis of the geographic distribution of each species allowed us to outline the prevalent North Atlantic affinity of the sponge community. Worthy of note is the new record of the alien calcareous sponge Paraleucilla magna of cryptogenic origin.

Two new species of Poecilosclerida (Porifera: Demospongiae) from Terra Nova Bay (Antarctic Sea)

Two new species of Poecilosclerida Crella (Crella) aurantiaca sp. nov. (Crellidae) and Mycale (Aegogropila) denticulata sp. nov. (Mycalidae) are described on the basis of material collected during the XX Italian Expedition (2004-2005) in Antarctica. Crella (Crella) aurantiaca sp. nov. is based on presence of acanthostyles of two size-categories. Mycale (Aegogropila) denticulata sp. nov. is characterized by the presence of palmate anisochelae and styles.

The aquiferous system of two Oceanapia species (Porifera, Demospongiae) studied by corrosion casts

Abstract. The aquiferous systems of two Indopacific Oceanapia species (Oceanapiidae) were studied by corrosion casts: O. amboinensis living in shallow lagoons and O. fistulosa living at the base of the reef slope. Both species show a massive, entirely buried body, emerging from the sediment only by long, completely close fistules. Particularly in O. fistulosa the corrosion casts revealed a complex, grape-like structure of the choanosome organised in anatomical and functional units composed by an incurrent web whose anastomosed meshes are crossed by a central excurrent canal. A system of thin canals connects the two systems giving rise to an area of choanocyte chambers. The corrosion casts revealed that in both species incurrent water penetrates into the sponge body by the fistules and that it is expelled through specialised structures buried in the sediment. This observation is in accordance with field experiments performed on O. fistulosa. In some specimens of this species, a solution of china ink injected into plastic bags enveloping the external fistules was observed, after waiting for a while, to flow through the buried structures.

Higginsia ciccaresei sp. nov. (Porifera : Demospongiae) from a marine cave on the Apulian coast (Mediterranean sea)

A new species of sponge: Higginsia ciccaresei sp. nov. (Demospongiae: Desmoxyidae) is described from a marine cave of the Ionian Apulian coast (Mediterranean Sea). It lives in complete darkness, 250 m from the cave entrance, in a basin of anchialine waters of low salinity and relatively cool temperature. The spicule formation process seems to be affected by some of the peculiar characteristics of the ambient water, resulting in spicules of unusual shape and irregular surface. This is the second record of the genus Higginsia – which has a world-wide distribution – from the Mediterranean Sea. The hypothesis that H. ciccaresei could be considered as a tethyan relic which survived in the peculiar habitat of an anchialine cave is also suggested.

Demosponge diversity from North Sulawesi, with the description of six new species

Abstract Sponges are key components of the benthic assemblages and play an important functional role in many ecosystems, especially in coral reefs. The Indonesian coral reefs, located within the so-called “coral triangle”, are among the richest in the world. However, the knowledge of the diversity of sponges and several other marine taxa is far from being complete in the area. In spite of this great biodiversity, most of the information on Indonesian sponges is scattered in old and fragmented literature and comprehensive data about their diversity are still lacking. In this paper, we report the presence of 94 species recorded during different research campaigns mainly from the Marine Park of Bunaken, North Sulawesi. Six species are new for science and seven represent new records for the area. Several others are very poorly known species, sometimes recorded for the second time after their description. For most species, besides field data and detailed descriptions, pictures in vivo are included. Moreover, two new symbiotic sponge associations are described. This work aims to increase the basic knowledge of Indonesian sponge diversity as a prerequisite for monitoring and conservation of this valuable taxon.

Hydrothermal waters enriched in silica promote the development of a sponge community in North Sulawesi (Indonesia)

Abstract Two shallow hydrothermal vents were investigated by SCUBA diving to evaluate their influence on the structure and diversity of a sponge community living close to the vent outflow, in the equatorial Pacific Ocean just off the coast of North Sulawesi, Indonesia (1°40.361ʹN, 125°8.112ʹE). No sponges identified were vent-obligate species, since they are found in the surrounding coral reefs too. The sponges were strongly attracted by the vent, concentrating in an area of a few meters around it, where they reached covering values up to 70% in the deeper vent and up to 42% in the shallower one. The high silica concentration, 8.5 mg L−1Si (deep vent) and 5 mg L−1Si (shallow vent), in hot spring water (90°C) was the putative environmental factor driving the sponge settlement and growth. These organisms take advantage of the increased silica availability that, facilitating skeleton formation, probably promotes sponge growth. This hypothesis is in agreement with the evidence that the spicules of the sponge specimens living around the hot springs have a thickness about double that of conspecific specimens present on the coral reefs at least 300 m away.