The present study aimed to improve the knowledge of the bivalve Pinna nobilis L. population distribution in Mar Grande of Taranto (Ionian Sea). Although historical references report the local abundant presence of this endangered species, there is a lack of updated information about its exact distribution. For this purpose, a visual census of P. nobilis was performed by SCUBA diving in the Mar Grande basin from September 2004 to March 2005. Pinnids were found at depths from 3 to 16 m, with a density ranging from 0.1 to 0.7 ind ha(-1). The survey method employed in this study was non-destructive, relatively simple to perform and easily applicable for monitoring studies. Field data were stored in a database and linked with the study area by means of the GIS technology. The results of the present study indicate a tentative of recovery of P. nobilis population in Mar Grande in spite of all the difficulties of a degraded and heavily polluted environment and the damages of illegal fishing methods.

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Despite numerous recent studies on the Gelidiales, most taxa belonging to this order are still difficult to distinguish when in the vegetative or tetrasporic state. This paper describes in detail the morphological and ontogenetic features of the prostrate system of the order with the aim of validating its diagnostic and taxonomic significance. Observations were made on fresh, liquid preserved and cultured thalli. The morphology of the attachment system and the characteristics of rhizoid ontogeny have proven to be useful diagnostic and taxonomic characters. Species belonging to Gelidium, Pterocladia and Pterocladiella bear true attachment organs consisting of cells of both exogenous and endogenous origin. In the family Gelidiellaceae, in contrast, attachment to the substratum is effected by single independent exogenous rhizoids. The attachment rhizoids of the Gelidiales, both exogenous and endogenous, are of the same cell type, and are the so-called hyphae, historically considered typical of the family Gelidiaceae only. A new subdivision of the Gelidiales into three families is proposed here, with the amendment of both Gielidiellaceae and Gelidiaceae, and the Pterocladiaceae fam. nov

The effects of global warming have been addressed on coral reefs in tropical areas, while it is still unclear how coral forests are reacting, particularly at temperate latitudes. Here we show how mesophotic coral forests are affected by global warming in the Mediterranean Sea. We highlight how the current warming trend is causing the lowering of the thermocline and it is enhancing mucilaginous blooms. These stressors are facilitating a massive macroalgal epibiosis on living corals, here reported for the first time from different areas in the Western and Central Mediterranean Sea. We provide a focus of this phenomenon at Tremiti Islands Marine Protected Area (Adriatic Sea), were the density of the endemic red gorgonian Paramuricea clavata decreased of up to 47% in 5 years, while up to the 96% of the living corals showed signs of stress and macroalgal epibiosis. Only populations deeper than 60 m depth were not touched by this emerging phenomenon. Spot observations performed at Tuscan Archipelago and Tavolara Marine Protected Area (Tyrrhenian Sea) suggest that this this combination of stressors is likely widespread at basin scale.

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