The status of the "Biocoenosis of the Infralittoral Algae" of the upper infralittoral zone (at 5 m depth) from two selected stations along the eastern coast of Sicily (Ionian Sea, Mediterranean) was studied with a multiproxy approach involving the study of algae and associated protist and animal organisms, including foraminifers, serpulids, molluscs, bryozoans and ostracods. Scraped samples (40x40 cm) were collected at selected seasons during a 2-year period (2015)(2016) in order to identify possible seasonal and spatial differences between the two stations, and to compare present data with historical ones. A community made up of the algae Halopteris scoparia, Padina pavonica, Dictyota dichotoma, Ellisolandia elongata and other encrusting coralline algae was found in sites historically colonised by a Cystoseira brachycarpa community, which was not found during our study. These algae presently structure the community and provide substratum for several associated epibiotic species. Hierarchical cluster analysis and Non-Metric Multi-Dimensional Scaling Ordination significantly differentiate the communities between the two stations but show no clear seasonal trend. Differences largely relate to changes in the algal vegetation and the impact produced by the regression of structuring species on epibionts (especially serpulids and bryozoans). Comparison with historical algal data from the area indicates the disappearance of Cystoseira brachycarpa, which was present at least until the late 1990s, and a community degradation with a considerable loss in species richness. This parallels observations in other Mediterranean areas, and could be related to an increase in population density of echinoids and their heavy grazing activity.

This paper describes 97 molluskan species (45 Bivalvia, 3 Scaphopoda, 49 Gastropoda) recovered from bathyal bottoms off Santa Maria di Leuca (Puglia, Italy), in the northern Ionian Sea, and provides data about their taxonomy, geographical distribution, habitat, ecological requirements and fossil record. Only 6 species remain unidentified, and all are illustrated. The bivalve-dominated assemblages belong to the so-called "cold-water coral ecosystem". They appear to depend mainly on substrate characteristics, with faunas related to hard substrate around coral-colonized mound tops, and mud-related ones in inter-mound areas, respectively. Nuculanoida and Pectinoidea among bivalves, and Conoidea and Pyramidelloidea among gastropods are the most diverse suprafamilial groups. The present paper is the first comprehensive taxonomic overview of Mediterranean bathyal mollusks including larval shell characters.

Along the Mediterranean Sea shelf, algal reefs made of crustose coralline algae and Peyssonneliales are known as Coralligenous. It ranks among the most important ecosystems in the Mediterranean Sea because of its extent, complexity, and heterogeneity, supporting very high levels of biodiversity. Descriptive approaches for monitoring purposes are often aimed at assessing the surficial ephemeral canopy, which is sustained and controlled by the occurrence of the long-lasting rigid structure at the base. This practice led to the non-univocal definition of Coralligenous, sometimes indicated as “animal Coralligenous” because of the surficial dominance of these components. The quantitative assessment of the builders that actively build up the persistent structure through geological time is therefore a fundamental topic. We collected two discrete coralligenous samples in front of Marzamemi village (Sicily, Ionian Sea), the first from an area of a dense coralligenous cover (- 37 m) and the second one from an area with sparse build-ups (- 36 m). By using image analysis and computerized axial tomography, we distinguished and quantified the different components both on the surface and inside the framework. In both cases, our results confirm the primary role of crustose coralline algae as major builders of the Mediterranean Coralligenous, this aspect matching with the evidence from the Quaternary fossil record. We suggest that the role of encrusting calcareous red algae in the Coralligenous should be considered in conservation and management policies.

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