Search

Coralligenous (C) is a type of Open Frame Reef, characterized by a variable association of calcareous red algae and macroinvertebrates. It is distributed across the Mediterranean shelf below the deepest seagrass meadows and down to the mesophotic zone, with different facies. The Italian project FISR “CRESCIBLUREEF” provided an extraordinary opportunity to explore the development of the Mediterranean C, from inception to present-day morphology and distribution off the SE coasts of Sicily. The spatial extension of C hybrid banks and discrete reliefs over the studied Sicilian shelf controls the hydrodynamics at the seafloor, the habitat biodiversity, and the related carbonate production at the shelf scale. The analyzed C samples, collected at about 36 m depth, had a columnar shape, were Holocene in age, and their development significantly modified the seafloor geomorphology. Our observations confirmed that most of the framework was built by calcareous red algae with an important contribution by bryozoans, with serpulids, molluscs, and rare corals as accompanying components of the sessile macroscopic fauna. The framework was highly porous, with a primary porosity derived from the growth, shape and structure of the skeletal components of both builders and dwellers, and an important secondary porosity derived from bioerosion and other early taphonomic processes involving both skeletonised and soft-bodied organisms, like sponges. During the entire process of framework growth and development, sponges played an important role as mineralization mediators of the autochthonous micrite fraction, which contributes significantly to the framework consolidation. Detrital micrite, rich in fine skeletal remains, is trapped in the primary and secondary cavities and represents an archive for the study of the organisms which are not directly involved in the framework building.

The Mar Menor is a hypersaline coastal lagoon representing one of the most iconic natural areas in Southeastern Spain. However, it has suffered several catastrophic environmental events causing an exceptional eutrophication status. A study was performed to assess the recruitment of oysters in the Mar Menor, determine their taxonomic allocation and evaluate functionality in filtration and growth A total of 45 spat collectors were installed in June 2020 and posteriorly retrieved in October 2020. In total, 3431 oyster recruits were counted. Two species of oyster Ostrea edulis and O. stentina, inhabit the Mar Menor, but they are indistinguishable at the morphological level when they are small. Thus, a genetic tool was developed to identify both species. From a total of 90 oyster recruits, 95% of them corresponded to O. stentina. Finally, growth rate and clearance measurements were conducted on 661 oysters over 6 months under laboratory conditions to explore their possible use in the bioremediation of the lagoon.

Although several bryozoans are considered habitat-former species, allowing colonisation by epibionts and promoting biodiversity, studies dealt so far with only some, usually constructional, species. In this context, the present study focuses on the epibiosis found on the erect mineralised but flexible species Margaretta cereoides, contributing with some macroalgae to the canopy formation on a coralligenous build-up collected at 36.7 m depth offshore Marzamemi (Ionian Sea, Mediterranean) in the frame of the project CRESCIBLUREEF. Focusing on bryozoans and serpulids we documented high diversity (species richness) on the investigated substrata (M. cereoides, Flabellia petiolata, Peyssonnelia rubra, Osmundaria volubilis and all other fleshy algae including Phyllophora crispa). Diversity, total number of colonies/specimens hosted, and number of colonies/specimens per cm2 are higher on M. cereoides than on algae, possibly in relation with the morphology, robustness and persistence of the surface offered by the bryozoan contrasting with the flexible and ephemeral nature of most algae, often provided with chemical defenses. Bryozoan and even more serpulid epibiont diversity on M. cereoides is also higher than those reported for studied species in the Mediterranean and for Flustra foliacea from North Europe.

The largest bivalve in the Mediterranean Sea, the fan mussel Pinna nobilis, is at risk of extinction due to mass mortality events (MMEs) caused by the spread of pathogens, Haplosporidium pinnae in particularly. In spite of being a protected area, Lake Faro (northeast Sicily, Italy) suffers from high anthropogenic pressures that affect the P. nobilis population that inhabits the lake and the two canals that connect it to the sea. In the present study, the population’s long-term changes have been monitored in three distinct periods: before the MME (2010), at the beginning of the epidemic spread along the Italian coasts (2018), and after the MME (2020). The survey, carried out by visual census, showed that, relative to 2010, the population of P. nobilis halved in 2018 and disappeared from the canals in 2020; while in the lake, living specimens were only 27.69 % of the total at this time, without recruits. The disappearance of P. nobilis, allowed rapid colonization by the congeneric Pinna rudis and the invasive oyster Pinctada imbricata radiata, which had never been recorded in the Lake Faro system before 2020.