QUATERNARY BUILD-UPS AND RHODALGAL CARBONATES ALONG THE ADRIATIC AND IONIAN COASTS OF THE ITALIAN PENINSULA: A REVIEW

In the Mediterranean, build-ups (created by coralline algae, Cladocora caespitosa, deep-water corals, vermetids, polychaetes and bacteria) and rhodolith beds are important hot-spots of biodiversity. Being severely threatened by anthropogenic impact and climate change, they have been included in international directives on environmental protection. This work wants to support the ongoing research on modern bioconstructions by providing further data on the long-term effects of environmental factors on these habitats. Our results are based on the analysis of the existing literature on the outcropping Quaternary successions of the Adriatic and Ionian coasts of peninsular Italy. The existing reports of build-ups and rhodalgal carbonates have been summarized in an homogeneous data-set and then studied to highlight distribution patterns in space and time. The analyses consistently outlined the importance of sedimentation rate in controlling the general distribution of build-ups and rhodalgal carbonates. The majority of the reports is concentrated south of the Gargano, where the sediment-load of the rivers is small. The majority of the reports is related to coralline algae, suggesting that they were the main carbonate producers during the period. C. caespitosa general distribution is mainly controlled by temperature, with most of the occurrences dating back to the warm periods of the late Ionian and of the Tarantian. Large build-ups of Cladocora are restricted to embayments and gulfs well-protected against storm waves. The distribution of the outcrops of deep-water corals is biased by the geological setting. A remarkable uplift is necessary to bring these corals from their original deep-water setting to elevated areas onshore. Consequently, most of the outcrops are in Southern Calabria which is characterized by a strong Quaternary uplift. Chemosynthetic build-ups, intertidal bioconstructions (made by vermetids, polychaetes or coralline algae), as well as stromatolites, are rare in the study area

LOWER OLIGOCENE CORALLINE ALGAE OF THE UROMIEH SECTION (QOM FORMATION, NW IRAN) AND THE OLDEST RECORD OF <em>TITANODERMA PUSTULATUM</em> (CORALLINOPHYCIDAE, RHODOPHYTA)

The Rupelian Uromieh section of the Qom Formation was analyzed with the aim to provide a first description of its coralline algal assemblages, and benthic paleoenvironmental evolution through time. The presence of Nummulites fichteli, Nummulites vascus, Halkyardia maxima and Subterraniphyllum thomasii, together with the absence of Nephrolepidina and Eulepidina confirm an early to middle Rupelian age. In the lower part of the section, the abundance of miliolids and corals suggests a proximal inner-platform environment, while upsection the increase in large rotaliids, coralline algae and bryozoans points toward a distal inner-platform/proximal middle-platform setting. Coralline algal assemblages support this interpretation, with Sporolithales and Hapalidiales becoming more common in the upper part of the section. Within the coralline assemblage, Lithoporella melobesioides and Titanoderma pustulatum are two of the most common species, together with articulated coralline algae. S. thomasii is more common in  coral-rich intervals, confirming that the distribution of this species was confined to shallow-water environments. The specimens of T. pustulatum recovered in the Uromieh section predate all the other known records of this species, indicating that the origin of T. pustulatum should be dated at least at the early Rupelia

Persististrombus latus (GMELIN) in the upper Pleistocene deposits of the marine terraces of the Crotone peninsula (southern Italy)

Persististrombus latus (GMELIN, 1791) (=Strombus bubonius LAMARCK, 1822), is the most iconic representative of the “Senegalese fauna”, a fossil assemblage of tropical water organisms thought to have colonized the Mediterranean Sea during the last interglacial. As such, P. latus has become an important stratigraphic marker of Marine Isotope Stage (MIS) 5.5, allowing the correlation of raised coastal deposits used in studies of sea level variations and tectonic uplift. P. latus is found in shallow marine sediments of Tyrrhenian age (~124 ka) in several localities of the Italian peninsula. However, despite intensive surveying through the years, the late Pleistocene marine terraces of the Crotone peninsula, which preserve an extensive volume of fossiliferous deposits attributed to MIS 5, have yielded very few specimens of P. latus. This paper reports the finding of several new specimens of P. latus near Isola di Capo Rizzuto, in deposits that had been independently assigned to MIS 5.5, and two specimens from the Capo Colonna terrace, which is thought to correlate with MIS 5.3 or 5.1. The Crotone peninsula, therefore, represents one of the few localities in Italy where multiple stratigraphically distinct P. latus-bearing units can be observed

Mean values (±SD) of calcification traits from SEM images (μm, otherwise differently specified).

Mean values (±SD) of calcification traits from SEM images (μm, otherwise differently specified).</p

Mollusk Thanatocoenoses Unravel the Diversity of Heterogeneous Rhodolith Beds (Italy, Tyrrhenian Sea)

Emerging evidence of rhodolith bed complexity and heterogeneity poses a challenge to monitoring strategies and questions about the role of abiotic factors in controlling the observed morphostructural diversity. Mollusk thanatocoenoses quickly respond to environmental conditions, expressing fidelity to biocoenosis and representing, thus, a useful ecological/paleoecological tool to unravel this heterogeneity. In this research, we studied three distinct rhodolith beds from the Tyrrhenian Sea (Italy), in a range between 40 and 100 m of water depth, together with their mollusk thanatocoenoses, sediment size, and oceanographic conditions. The beds are all heterogeneous and rarely correspond to a specific rhodolith morphotype and shape. On the contrary, the study of the associated thanatocoenoses led to distinguish at least five different assemblages within the known variability of the Coastal detritic (DC) association. DC and deep mud (VP) mollusk species dominate hanatocoenosis A, which is associated with mixed sediment and a low hydrodynamic regime. Thanatocoenosis B corresponds to an assemblage in which DC species mixed with species of adjacent vegetated bottoms in sandy sediment with a medium hydrodynamic. Thanatocoenosis C includes species related to muddy coastal detritic (DE) and offshore detritic (DL) associated with sand and a variable proportion of praline and branch morphotypes. Thanatocoenoses D and E include a wide range of detritic species (DE DC, DL) together with VP and coralligenous (C), associated with exclusive praline and gravelly sand (Thanat. D), or a mixed proportion of branch and praline and mixed sediment (Thanat. E). Our results demonstrate that the study of mollusk thanatocoenoses provides insights into the diversity within and among heterogeneous rhodolith beds. Moreover, rhodoliths, as part of the sediment, create microhabitats suitable for a wide range of mollusk species that contribute to the formation of complex thanatocoenoses

Comparison of mean values for short and long cells in <i>L</i>. <i>racemus</i> DB867.

The numbers inside the plots indicate the mean values for the cell wall area, cell lumen area, SC thickness and PC thickness.</p

<i>L</i>. <i>racemus</i>, <i>L</i>. <i>pseudoracemus</i>, <i>L</i>. cf. <i>pseudoracemus</i> and <i>L</i>. cf. <i>racemus</i> specimens examined under SEM.

L. racemus, L. pseudoracemus, L. cf. pseudoracemus and L. cf. racemus specimens examined under SEM.</p

SEM details of the calcification in <i>Lithophyllum racemus</i>.

(a) Calcified perithallial cells; (b) magnification of the inset in (a): rhomboidal crystallites of the primary calcification (PC, arrow) embedded in organic microfibrils (arrow); (c) transverse section of the perithallus; (d) magnification of the inset in (c) showing the innermost calcified layer (IC, arrow); (e) secondary hypothallus over the conceptacle pore canal in Fig 1H; (f) magnification of the inset in (e): regular rhomboidal crystallites of the hypothallial PC (arrow).</p

Results of statistical tests.

Testing the difference of the perithallial cell area of L. racemus (DB661, DB867), L. pseudoracemus (DB768, DB835), L. cf. racemus DB865, and L. cf. pseudoracemus DB866. Statistically significant p-values are given in bold. Kruskal-Wallis test significance at α = 0.05; Dunn’s test significant at p ≤ α/2. (DOCX)</p

Principal component analysis (PCA).

Score plot is shown in (a); loading plot of PCA on calcification data in both perithallial (P.) and epithallial (E.) cells (b). The plots model 83% of the total data variance. Variance proportions are shown along each component axis. Calcification types are evidenced with circles and classified in L. racemus type and L. pseudoracemus type.</p