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Despite their strong Raman scattering and importance in several applications in the geological and biological sciences, Mg-calcites have not been thoroughly investigated by Raman spectroscopy. In this study, we investigated whether Raman spectra of carbonates are sensitive to the structural and chemical changes occurring when Mg2+ substitutes Ca2+ in the calcite lattice. Different carbonate samples with variable Mg content (from 0 to 20 mol% MgCO3) of biological and inorganic origin have been first beamed under a Raman spectrometer and then analysed by scanning electron microscopy-energy dispersive spectrometer and electron microprobe analysis-wavelength dispersive spectrometer microprobes to determine their chemistry. The biological samples (foraminifers, algae, barnacles and echinoderms) were collected from areas situated at different latitudes and water temperature and saturation, factors affecting the chemical and isotopic composition of shells in marine organisms. The Raman band positions are directly linked to the amount of magnesium present in the calcite lattice, and all peaks of Mg-calcite spectra show a consistent and linear increase in Raman shifts according to their Mg content, which is a consequence of the decreased inter-atomic distances following the substitution of Ca2+ with the smaller Mg2+ ion. This study demonstrates that Raman spectroscopy provides an innovative work perspective in marine biology, provenance studies and oil exploration when estimates of mineralogical and chemical changes are the focus of the study. Raman spectroscopy is even more attractive – for the mentioned fields of research – than many other methods because of the non-destructive nature and its very short analytical time

The sequence stratigraphic framework and a summary of the fossil fauna of the upper Miocene portion of the Pisco Formation exposed along the western side of the Ica River (southern Peru) is presented through a new geological map encompassing an area of about 200 km2 and detailed chronostratigraphic analyses. Extensive field mapping and sedimentological study of outcrop sections have shown that the Pisco Formation is a cyclical sediment unit composed of at least three fining-upward, unconformity-bounded depositional sequences, designated P0, P1, and P2 from oldest to youngest. In the study area, these sequences progressively onlap a composite basal unconformity from southwest to northeast. Integration of biostratigraphic and tephrochronologic age determinations constrains the ages of the three Pisco sequences within the study area. Based on the age of surrounding sediments, a conservative estimate of the age of P0 suggests deposition of these strata between 17.99 ± 0.10 Ma and 9.00 ± 0.02 Ma, whereas diatom biostratigraphy and calculated 40Ar/39Ar ages converge to indicate that strata of the P1 sequence were deposited sometime between 9.5 Ma and 8.9 Ma and that those of the P2 sequence are younger than 8.5 Ma and older than 6.71 ± 0.02 Ma. Our survey for both vertebrate and macro-invertebrate remains in the three sequences confirms the outstanding paleontological value of the Pisco Formation and contributes to depict regional faunal shifts in the fossil assemblage., Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy), V. 123, N. 2 (2017)

The J.H. Johnson Collection, which is deposited at the National Museum of Natural History in Washington D.C., may be split into discrete sections, one of which is dedicated to the post-Carboniferous calcareous fossil algae of Guatemala. The contents of the latter, which was established more than half a century ago and which is a reference section for the Americas (for a long time, it was the only one), is reassessed here in the light of the recent advances in paleophycological systematics. Ascriptions to species, genera and higher taxonomic ranks of these Chlorophyta, Rhodophyta and microbial structures are sometimes confirmed or more often revised. Despite limited information, in some cases it was possible to refine or even correct the ages of the fossil strata, which span the Permian - Miocene interval. La Collection J.H. Johnson déposée au National Museum of Natural History à Washington D.C. peut être subdivisée en sous-collections dont une dédiée aux « algues calcaires » fossiles post-Carbonifère du Guatémala. Le contenu de cette sous-collection de référence pour les Amériques (ce fut longtemps la seule) et constituée il y a plus d’un demi-siècle est réexaminée ici à la lueur des avancées récentes en systématique paléophycologique. Les attributions spécifiques, génériques et/ou supragénériques de ces Chlorophytes, Rhodophytes et structures microbiennes sont parfois confirmées, sinon le plus souvent révisées. Malgrè le peu d’éléments à notre disposition, dans certains cas, il a été possible de préciser - voire de corriger - l’âge des gisements qui sont répartis entre le Permien et le Miocène

The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries. A total of 257 benthic marine habitat types were assessed. In total, 19% (EU28) and 18% (EU28+) of the evaluated habitats were assessed as threatened in categories Critically Endangered, Endangered and Vulnerable. An additional 12% were Near Threatened in the EU28 and 11% in the EU28+. These figures are approximately doubled if Data Deficient habitats are excluded. The percentage of threatened habitat types differs across the regional seas. The highest proportion of threatened habitats in the EU28 was found in the Mediterranean Sea (32%), followed by the North-East Atlantic (23%), the Black Sea (13%) and then the Baltic Sea (8%). There was a similar pattern in the EU28+. The most frequently cited pressures and threats were similar across the four regional seas: pollution (eutrophication), biological resource use other than agriculture or forestry (mainly fishing but also aquaculture), natural system modifications (e.g. dredging and sea defence works), urbanisation and climate change. Even for habitats where the assessment outcome was Data Deficient, the Red List assessment process has resulted in the compilation of a substantial body of useful information to support the conservation of marine habitats.

Lithothamnion crispatum is a nongeniculate coralline alga of the Hapalidiaceae family, with a cosmopolitan distribution. It occurs in the Mediterranean, in the Atlantic and Indian Ocean and in the Pacific Ocean along the Eastern coast of Australia (Basso et al. 2011). The plants either grow unattached, forming rhodoliths, or attached on hard substrate; they have been found from 2 to 80 meters of water depth (Keats et al. 2000; Nobregas-Farias et al. 2010; Basso et al. 2011). Until now L. crispatum has not been recorded in the fossil. A revision of fossil specimens, ranging in age from Eocene to Pleistocene, proved that this species has a long stratigraphic distribution, starting approximately 40 Ma ago, without significant morphological changes in both reproductive and vegetative structures (Fig. 1). The species has a fruticose to foliose growth form with a thallus organized in a plumose hypothallium (ventral core) and a zoned perithallium (peripheral zone). Perithallial and hypothallial cells are connected by cell fusions. Secondary pit connections and trichocytes have not been observed. Epithallial cells are flattened and flared; subepithallial initial are as long or longer than their derivatives. Tetra/bisporangial conceptacles are multiporate, their roof is slightly protruding above the surrounding thallus surface and is characterized by a depression on the top of pore canals (Fig. 1A-D). This depression is generated by the disintegration of the last cell of the roof, and the resulting pit overlays wedge-shaped cells, which, in surface view, appear as a rosette bordering the pore canal (Fig. 1E-H). Conceptacle roofs pitted with depressions originating from the degeneration of the uppermost cells in filament bordering the pore canal is a unique diagnostic feature which distinguishes L. crispatum from other species of its genus (Wilks and Woelkerling 1995; Basso et al. 2011). This morphological character was used to merge Lithothamnion indicum and Lithothamnion heteromorphum into Lithothamnion superpositum (Nòbrega-Farias et al. 2010) and later to consider L. superpositum conspecific of L. crispatum (Basso et al. 2011). The biometric parameters preserved in the fossil specimens perfectly fit those of the modern species, both in range and in average values, showing no remarkable changes through time. Miocene samples, collected from different localities of the Tertiary Piedmont Basin, of the Alpine Foreland Basin and of the Paratethys, proved that no significant morphological variation existed between populations from different geographical areas. The only exception is a specimen from the Middle Miocene of Romania: while the main morphologic features (vegetative structure, length and width of vegetative cells, size and characteristics of asexual conceptacles) correspond to those of all the other samples, this one shows considerably larger and deeper pits on the conceptacle roof. No remarkable differences were observed between the samples of the Mediterranean Miocene and those of the Mediterranean Pleistocene even though the latter developed in cooler water. Morphologically speaking it is then safe to state that L. crispatum is much older than previously though and that can be traced back to the Eocene. It occurs, without significant variations, in different geological epoch, and has a cosmopolitan distribution. Its presence in such a broad range of environments suggests that this species is highly adaptable. Moreover, although the ve advantage of its particular roof morphology is still unknown, it appears as a successful and persistent feature. Even if the morphological features does not allow the separation of the fossil and the recent material, neither according to their geographic provenance, nor by their age, the possibility that this morphological species could represent a group of diverse cryptic entities cannot be ruled out. References Basso, D., Rodondi, G. and Bressan, G., 2011: A redescription of Lithothamnion crispatum and the status of Lithothamnion superpositum (Rhodophyta, Corallinales), Phycologia, 50, 144-155. Keats, D.W., Maneveldt, G. and Chamberlain, Y.M., 2000: Lithothamnion superpositum Foslie: a common crustose red alga (Corallinaceae) in South Africa, Cryptogamie Algologie, 21, 381-400. Nòbrega-Farias, J., Riosmena-Rodriguez, R., Bouzon, Z., Oliveira, E.C. and Horta, P.A., 2010: Lithothamnion superpositum (Corallinales; Rhodophyta): First description for the Western Atlantic or rediscovery of a species?, Phycological Research, 58, 210-216. Wilks, K.M. and Woelkerling, W.J., 1995: An account of Southern Australian species of Lithothamnion (Corallinaceae, Rhodophyta). Australian Systematic Botany 8(4) 549 - 583.

Fossil crustose coralline framework are known from the Eocene onward, with occurrences in middle Eocene of Spain, the Upper Eocene of Northern Italy, the Miocene of Malta and Poland and the Plio-Pleistocene of the Mediterranean. The studied example presents a coralline algae framework from the Upper Eocene of Northwestern Italy. Although the carbonate platform where the build-up developed is lost, its remains are preserved. Reworked skeletal grains, transported off shore by debris-flow, are preserved in the Ternate Formation, a deep-water sub-marine fan. In the Upper Oligocene conglomerates of the Gonfolite Lombarda Group, biogenic carbonate pebbles of Upper Eocene age are preserved. Textural characteristics, skeletal assemblages, coralline-algae flora and benthic foraminifers composing the pebbles were studied and compared to those of Ternate Fm. The same rhodalgal skeletal-assemblage, the same species of coralline algae and the same association of benthic foraminifers were found in both set of samples, suggesting their common origin. While Ternate Fm. materials were undoubtedly reworked during transport, the limestone pebbles are pristine fragments of the original carbonate platform which was uplifted and eroded between Upper Eocene and Upper Oligocene. They actually have no internal textural features suggesting reworking (common orientation of the grains, high degree of sorting, presence of rip-up clasts, fragmentation of delicate skeletal elements). The remnant of the crustose coralline framework was preserved in these pebbles. Neogoniolithon sp. is the most common crust-forming species, this alga has the ability to grow directly over fine grained mobile substrate and thus has a pivotal role in framework formation. Although the preserved framework was only observed in limestone pebbles, fragments of Neogoniolithon sp. crusts were commonly observed in all the samples of Ternate Fm., testifying the importance of this framework builder in the carbonate factory. Sporolithon aschersonii and the encrusting foraminifer Acervulina linearis, together with encrusting bryozoans also contributed to the building of the framework. Compared to other European examples of the same age the studied skeletal association lacks fragments of hermatypic corals. The exclusion of corals may have been caused by the general instability of the environment. Ternate Fm. sub-marine fan was supplied by periodic debris flow, probably started by river floods. These events were able to sweep away the platform with enough energy to carry large boulders and to rip away fragments of the substrate several meters in length. Lumps of sediment, rich in hydrocarbons and pyrite, have been observed in the Ternate Fm., suggesting that bottom waters were occasionally and locally depleted in oxygen. The lack of oxygen was probably caused by recurrent high riverine discharge of organic matter and nutrients. The combined stressful effects of bottom instability and riverine discharge probably excluded corals from the association. The integrated study of the abundant but reworked materials of the Ternate Fm. and of the pristine, but rare, limestone pebbles of the Gonfolite Group allowed the reconstruction of a otherwise lost Eocene carbonate factory.

Most paleontological information is given with reference to species, as it happens in biology. Systematics delimits species and requires a species concept. Because of the importance of the definition of species, and in search of a unifying concept including uniparental and biparental groups, many species concepts have been proposed in biology (Hausdorf 2011) although the most influential one is: “groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups” (Mayr 1942). Reproductive isolation is the most common cause of genetic divergence, and speciation is the stage where the diverging populations will not lose their divergence upon contact, and continue to diverge. Through time, neutral mutations that do not affect phenotype can cumulate by genetic drift. In other cases, non-neutral mutations lead to increasingly divergent genotypes and phenotypes showing differential adaptation to their niche, filtered by natural selection. Coralline algae possess both a vegetative and a sexuate reproduction. The first produces clones of the parent individual, while the second implies genetic recombination. After Woelkerling (1988) seminal work, paleobotanists strove to match the definitions and criteria of the biological systematic framework, as far as allowed by the preservation of delicate features in the fossil (Braga et al., 1993). In addition, the study of recent material by a paleontological approach was explored, as a tool to understanding the information loss due to taphonomic processes and to different techniques and preparations of fossils vs. modern specimens (Basso, 1994). At the same time, many efforts were devoted to critical revisions of the type material of coralline algae in historical collections, in order to re-describe live and fossil species in a modern taxonomic context. Strong emphasis was given to: 1) the large variability and morphological plasticity of coralline algae; 2) the need of a statistical treatment of biometric data; 3) the criticism of the validity of many taxa based on subtle morphological or size differences of anatomical features, poor descriptions, poorly preserved or sterile specimens, or single specimens. As a result, the fossil coralline diversity, as apparent in the early literature, started to be perceived as an artifact due to confused definitions and unclear diagnostic characters, with the caveat that the true number of different species had to be probably much lower. Waiting for a complete revision of the hundreds of living and fossil species described so far, (paleo)algologists started to give less and less importance to characters like growth-forms, biometric data, trichocyte occurrence, palisade cells occurrence, etc. in the conceptual framework of the high plasticity of coralline species. This process had important consequences on our knowledge: for example, Titanoderma was merged into Lithophyllum (Campbell & Woelkerling 1990), and, given the difficulty to find unequivocal reference for most taxa, paleobotanists simply gave up attempting coralline identification at the species level. However, the use of an open nomenclature in coralline taxonomy, although justified by the need to avoid further nomenclatural confusion, is a frustrating exercise, since it leads to artificially simple and repetitive patterns of genera distribution. Moreover, dealing solely with supraspecific ranks leaves the coralline paleoecological (and stratigraphic?) potential and their evolutionary pattern largely unexplored. The paleontological species is necessarily a morphological species, since neither genetics, nor interbreeding can be checked on fossils, and its recognition must be based solely on observable diagnostic characters. Other considerations, such as the coherence of species identification with its known stratigraphic or paleogeographic range should be discussed at a further stage. In other words, whenever clear diagnostic characters are identified both in living corallines and also detected in the fossil, the straightforward conclusion is that the considered entities are conspecific, no matter of age and geography. This concept was far to be accepted by the scientific community that was using “a priori” different names for live and fossil species, until the first paper synonymizing fossil species with their modern morphological counterpart appeared (Basso et al. 1996). Molecular genetics is radically changing again our point of view. Recently, the increasing use of genetic analysis for the identification of species revealed that, in many cases, coralline specimens apparently belonging to the same morphological species are genetically different (Pardo et al., 2014). The discovery of this unexpected coralline biodiversity is accompanied by an effort to identify those combinations of morphological characters that would support species identification as from molecular genetics, in the so-called integrated taxonomy (Hebert et al., 2005; Basso et al., 2015). In particular, molecular genetics is revaluating some aspects of coralline morphological variability, unequivocally establishing that they have importance in species diagnosis. Actually, Titanoderma has been finally reconsidered as a distinct genus, and other believed examples of extreme morphological variability are presently considered a case of erroneous mixing up of different species under the same name (i.e. L. margaritae). While twenty years ago we were convinced that an unrealistic number of coralline species existed in literature, we are now facing the fact that, based on the present-day discovery of unsuspected genetic diversity, we should expect the other way round. Accurate revisions and re-documentation of type collections is still the main tool we have to clarify coralline taxonomy, both in biology and in paleontology. Paleoalgologists shall probably go on using an open nomenclature when no better choice is available. However, this cannot be our default choice, as far as we can already refer to those species, either modern or fossil, that are presently known with adequate morphological detail (Hrabovský et al., in press). References Basso, D., 1994: Living calcareous algae by a paleontological approach: the non-geniculate Corallinaceae (Rhodophyta) of the soft bottoms of the Tyrrhenian Sea (Western Mediterranean). The Genera Phymatolithon Foslie nom. cons. and Mesophyllum Lemoine. Riv. It. Paleont. Strat., 100 (4), 575-596. Basso, D., Fravega, P. and Vannucci, G., 1996: Fossil and living corallinaceans related to the Mediterranean endemic species Lithophyllum racemus (Lamarck) Foslie. Facies, 35, 275-292. Basso, D., Caragnano, A., Le Gall, L. and Rodondi, G., 2015: The genus Lithophyllum in the north-western Indian Ocean, with description of L. yemenense sp. nov., L. socotraense sp. nov., L. subplicatum comb. et stat. nov., and the resumed L. affine, L. kaiseri, and L. subreduncum (Rhodophyta, Corallinales). Phytotaxa, 208 (3), 183–200. Braga, J-C., Bosence, D.W.J., and Steneck, R.S., 1993: New anatomical characters in fossil coralline algae and their taxonomic implications. Palaeontology, 36, 535–547. Campbell, S.J. and Woelkerling, W.J., 1990: Are Titanoderma and Lithophyllum (Corallinaceae, Rhodophyta) distinct genera? Phycologia, 29, 114–125. Hausdorf, B., 2011: Progress toward a general species concept. Evolution, 65(4), 923-931. Hebert, P.D. and Gregory, T.R., 2005: The promise of DNA barcoding for taxonomy. Systematic Biology 54(5): 852‐859. Hrabovský, J., Basso, D. and Doláková, N., in press: Diagnostic characters in fossil coralline algae (Corallinophycidae, Rhodophyta) from the Miocene of southern Moravia (Carpathian Foredeep, Czech Republic). Journal of Systematic Palaeontology Mayr, E., 1942: Systematics and the origin of species. Columbia Univ. Press, New York. Pardo, C., Lopez, L., Peña, V., Hernandez-Kantun, J., Le Gall, L., et al., 2014: A multilocus species delimitation reveals a striking number of species of coralline algae forming maerl in the OSPAR maritime area. PLoS ONE, 9(8): e104073. doi:10.1371/journal.pone.0104073. Woelkerling, W.J., 1988: The Coralline red algae: an analysis of the genera and subfamilies of nongeniculate Corallinaceae. British Museum (Natural History). Oxford University Press, 268 pp.

Carbonates factories grain association is related to environmental temperature. Tropical platforms are dominated by hermatipic corals and calcareous green algae as main sediment producers, while at higher latitudes bryozoans, mollusks and benthic foraminifers dominate. Calcareous red algae may occur or even be locally dominant on the shelf across all latitudes. Temperature and light control carbonate production from the chemical and biological point of view acting on both equilibrium of calcium carbonate minerals and metabolic rate of organisms. A third parameter controlling the biogenic carbonate production is nutrients availability. Growth of photosynthesizing organisms depends on nutrient concentration in water. Increase in plankton biomass, boosted by phosphorus, nitrogen and iron abundance, enhances the particulate organic carbon (POC) which in turn reduces water transparency and light availability to the benthic community (Hallock and Schlager, 1986). For example, in the present-day Gulf of California, where eutrophic condition prevails, cool-water carbonate assemblages are present on the shelf, while, according to temperature, a warm-water association would be expected (Halfar et al., 2006). In recent sediments this kind of situation is easily detected since low percentages of warm-water carbonate bioclasts (like hermatipic corals) are mixed up with cool water ones. On the contrary, preferential dissolution of aragonite and high-Mg calcite skeletal particles during fossil diagenesis affect the grain association with the consequent loss of ecological information. The bioclastic limestone of the Pietra da Cantoni Group (Monferrato, Piedmont Tertiary Basin) developed during the lower Miocene in a warm climate. The carbonate assemblage is largely dominated by calcareous red algae and large benthic foraminifera, however, prominent variations locally occur. In Castello di Uviglie and Villa San Bartolomeo quarries, levels of rhodolithic rudstone, are composed of barnacle plates (40%), calcareous red algae thalli (35%), bryozoan colonies (5%) and by lesser amount of mollusks, benthic foraminfers, serpulid worms and echinoids. Melobesioids dominate (>80%) the algal assemblage of rhodoliths, as frequently observed in cool water or in deep warm-water associations (Adey, 1979). The tropical origin of the limestone has been assessed by a detailed paleontological analysis of both fossil flora and fauna. In the algal assemblage few thalli of the warm-water genera Sporolithon and Lithoporella have been identified, along with the foraminifers of the genus Amphistegina and the species Operculina complanata and Stomatorbina torrei. Barnacles plate accumulation is the most outstanding feature of these rocks. In the fossil record extensive deposits of barnacle plates are known and widespread in the Pliocene limestone of New Zealand, and have been interpreted as formed in a current-swept temperate to cool benthic environment (Kamp et al., 1988). In the present-day ocean, similar sediments accumulate on isolated and current-dominated banks in the Barents Sea (Henrich and Freiwald, 1995). However, the barnacles of Pietra da Cantoni Group. belong to the Balanus trigonus “group” which is composed by sub-tidal warm-waters species. Amongst bryozoans, Bifissurinella lindenbergi, belonging to the problematic Bicorniferidae family, is the most abundant element. This uncommon fossil species is exclusive of Neogene warm-water associations, and in the Pietra da Cantoni limestone its distribution seems to be tied to the barnacle abundance. Such a peculiar carbonate assemblage, mainly composed of warm-water suspension-feeders, with the noteworthy absence of symbiont-bearing organisms, probably formed in POC-rich and high-energy tropical waters. The organic carbon provided plenty of food to suspension feeders, like barnacles and bryozoans, and reduced light availability at the seafloor, thus explaining the red algal assemblage. Currents possibly delivered food to the suspension feeders and at the same time prevented fine sediment settling, also contributing to the increase of primary production by mixing up the water column. The interplay of these environmental factors resulted in high primary porosity, which is preserved in the studied limestone (Fig1). The barnacle-dominated facies of the Miocene Pietra da Cantoni Fm. represents a fossil example of prevailing non-oligotrophic conditions which largely exclude hermatypic corals and allow the deposition of cool-water assemblages in warm water. This effect could solely be identified through a paleontological analysis taking into account the complete array of biotic components along with chemistry and mineralogy of the limestone.

Autochthonous coralligenous build-ups are mainly formed by encrusting coralline algae, currently develop on Mediterranean hard and soft bottoms with a patch distribution along the coast. However, few fossil examples have been described in the literature and their evolution in the context of a stratigraphic cycle has seldom been modelled in detail (Basso et al., 2007; Titschack et al., 2008). Wide marine terraces are preserved in the area of the Crotone peninsula, Ionian Calabria, southern Italy (Zecchin et al., 2004; Nalin et al., 2006; Nalin et al., 2009). They are related to the interplay between Pleistocene sea-level changes and the progressive uplift of the Calabrian arc from the middle Pleistocene onwards (Massari et al., 2002). The deposits are up to 10 m thick and consist of mixed carbonate and siliciclastic sediments, in which coralligenous build-ups and other red algal facies are dominant. Usually the terraces are characterized by 3 layers: 1) a blocked basal conglomerate, forming by the erosion of ancient terrace deposits; 2) the algal reefs; 3) the biogenic sandstone-grainstone bodies, which occupy the cavities between the coralligenous bodies and/or cover them at the top. These 3 layers are the result of the shallow deposition during an entire sea-level cycle. The two youngest marine terraces are related to Marine Isotopic Stage (MIS) 3 and 5.1 (Gliozzi, 1987; Belluomini et al., 1988; Palmentola et al., 1990; Zecchin et al., 2004; Nalin, 2006). The MIS 3 terrace outcrops in the area of Le Castella, S of Isola di Capo Rizzuto village whereas the MIS 5.1 is placed along the Capo Colonna cape, placed in the NE part of the peninsula. Their major stratigraphic features and facies have been already described but very few details exist on their paleontological content. Stratigraphic sections in both terraces have been measured and sampled. Thin sections have been prepared for red algae identification and to measure the diagnostic anatomical microfeatures of the algal thalli in order to conduct statistical analysis. Sandstone and grainstone associated to build-ups have been disgregated in order to separate particles in a conservative way and conduct paleontological analysis of the algal fragments forming the sediment. The coralligenous build-ups are dominated by the coralline algae Mesophyllum alternans (Foslie) Cabioch & Mendoza and Titanoderma pustulatum (Lamouroux) Nägeli usually alternated with bryozoan crusts. Other red algae species like Lithophyllum stictaeforme (Areschoug) Hauck, Phymatolithon calcareum (Pallas) W.H. Adey & D.L. McKibbin and Neogoniolithon sp. rarely occur. A quantification of the dominant coralline species involved in the bioconstruction and forming the sediment is provided, in order to define the coralline assemblage variation in a shallowing-upward paleoenvironment. The relative abundance of each coralline species provides more details on the behaviour of the identified species and allows a better correlation with the sea-level cycle. The paleontological results have been framed in the context of a geneticstratigraphic interpretation of the marine terraces.

Autochthonous carbonate build-ups are mainly formed by encrusting coralline algae, which are one of the most important carbonate sediment contributors in the benthic communities of the Mediterranean area. They represent one of the most productive ecosystems in temperate regions and currently develop on Mediterranean hard and soft bottoms with a patch distribution along the coast. Light, salinity and temperature seem to be the main environmental factors influencing their distribution. Several types of assemblages have been described so far, due to the high heterogeneity of coralline growth-forms, distributed from the intertidal down to 160 m water depth, from rhodolith-beds to coralligenous build-ups. In particular, coralligenous build-ups are frameworks with three-dimensional structure that serve as shelter and provide storm protection by buffering wave action along coastlines. Coralline red-algae build-ups have high potentiality to be conserved in the fossil record. However, few fossil examples have been described in the literature and their evolution in the context of a stratigraphic cycle has seldom been modeled in detail. Wide marine terraces are preserved in the area of the Crotone peninsula, Ionian Calabria, southern Italy. They are related to the interplay between Pleistocene sea-level changes and the progressive uplift of the Calabrian arc from the middle Pleistocene onwards. These terraces overlie a Plio-Pleistocene slope succession (Cutro Marly Clay Fm). The two youngest marine terraces have been correlated with Marine Isotopic Stage (MIS) 3 and 5.1. Many authors have already studied the deposits of these terraces, defining their major stratigraphic features and facies, but very few details exist on their paleontological content. The deposits up to 10 m thick consist of mixed carbonate and siliciclastic sediments, in which red-algal reefs (= coralligenous build-ups) and other red algal facies are dominant. Stratigraphic sections in both terraces have been measured and sampled in order to obtain a complete spatial description of the terrace deposits. Samples have been collected both in the red algae facies and in the grainstone and sandstone that occupy the cavities within the main algal bodies. Thin sections have been prepared for red algae identification. A statistical analysis has been performed on the diagnostic anatomical microfeatures of the algal thalli. Bio-calcarenite have been disgregated in order to separate particles in a conservative way and conduct the quantitative paleontological analysis of the molluskan shell assemblages along with grain-size and chemical analyses. Species identification of bryozoans has been provided for facies dominated by this taxon. The coralligenous build-ups are dominated by Mesophyllum alternans (Foslie) Cabioch & Mendoza and Titanoderma pustulatum (Lamouroux) Nägeli usually alternated with bryozoans crusts. Other red algae species like Lithophyllum stictaeforme (• • Areschoug) Hauck, Phymatolithon calcareum (Pallas) W.H.Adey & D.L.McKibbin and Neogoniolithon sp. rarely occur. The molluskan assemblages in the grainstone associated to algal build-ups vary from typical coralligenous (C) to coastal detritic (DC), whereas they record an infralittoral environment in the uppermost unit. The paleontological results have been framed in the context of a genetic-stratigraphic interpretation of the marine terraces.

The Intergovernmental Panel on Climate Change (IPCC, 2001) predicted that the atmospheric partial pressure of carbon dioxide (pCO2) will be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years. Between 2100 and 2200, the atmospheric CO2 concentration is expected to increase to the range of 1500 to 2100 ppm that is 100 times greater than the natural fluctuations seen over recent millennia, in contrast to the stability of the past 24 million years during which time levels have remained below 500 ppm (Pearson & Palmer, 2000). As CO2 dissolves in the surface ocean it reacts with water to form ‘protons’ (H+) and dissolved inorganic carbon (DIC), which is the sum of the concentrations of carbonic acid (H2CO3), bicarbonate (HCO3–), and carbonate ions (CO32–)stored in the ocean. With increasing atmospheric pCO2, DIC will increase and the equilibrium of the carbonate system will shift to higher CO2 and HCO3– levels, while CO32– concentration and pH will decrease. These changes in carbonate chemistry, often referred to as ‘ocean acidification’, are already occurring. Current models predict that the pH of surface seawater will drop from 8.0 to 7.8 by the year 2100 (Royal Society, 2005). This dramatic change in seawater chemistry is likely to have a large impact on marine life and biogeochemical processes such as reduced biogenic marine carbonate mineral production and carbonate mineral dissolution. Assessing the impact of decreasing pH on coastal ecosystems is priority and the focus here is on calcareous algae, and on coralline red algae in particular, as carbonate component of the sediment. The precipitation of calcium carbonate is a source of CO2, whereas carbonate dissolution results to lower it (Frankignoulle et al, 1994). Therefore, carbonate dissolution is expected to buffer ocean acidification and to play an important role in the global change, though it is likely that the natural process of carbonate dissolution will be too slow to neutralize the fossil fuel CO2 (Broecker & Takahashi, 1977). Calcium carbonate occurs in natural biogenic sediments as aragonite or calcite. Magnesium (Mg2+) can substitute some of the Ca2+ in the lattice and the calcite containing >4% wt of MgCO3 is conventionally defined high-Mg calcite or Mg-calcite. The extent to which a biogenic carbonate particle is prone to dissolution in seawater depends from several factors, among which the leading ones are mineralogy and the calcium carbonate saturation state , which is dependent from the [CO32–]. The solubility of CaCO3 increases with depth. Presently, surface ocean waters are supersaturated with respect to both aragonite and calcite, but the aragonite and calcite saturation horizons of the world’s oceans are moving to shallower depths at a rate of 1-2 m per year (Guinotte & Fabry, 2008) due to the rapid influx of anthropogenic CO2 to the oceans. Aragonite is more soluble than calcite in the same seawater, but natural Mg-calcites containing > 8- 12 mol% MgCO3 are more soluble than aragonite,being the most sensitive responder to a lowering pH (Morse et al, 2006; Kuffner et al, 2008). The recruitment rate and growth of crustose coralline algae is severely inhibited under elevated pCO2 (Hall-Spencer et al, 2008). Corallinales, which are a major framework builder in temperate and cold water, are vulnerable to ocean acidification due to the solubility of their high magnesium calcite cell-walls (Kuffner et al,2008). Cool-water carbonate-rich sediments of the world shelf, often dominated by calcareous red algae, are a major CaCO3 reservoir, that can react by dissolution to a decrease of the saturation state of the seawater (Morse et al, 2006). However,despite the occurrence of a suite of local data-base on various sediment characteristics, the algal carbonates have been not characterized and quantified on a large scale, therefore preventing any hypothesis on their role as buffer in a future scenario of acidified oceans. Shelf sedimentary facies of the temperate and cold zones are enriched in calcite and Mg-calcite (from mollusks, forams and red algae). By contrast, aragonite dominates the sediments of the tropical oceans (from corals and green algae). Existing deposits of highly soluble, Mg-calcite and aragonite sediments require quantification to assess their importance as a possible buffer to acidification. What is the contribution of algae to this carbonate budget? The scientific literature started to re-evaluate the geologic role of coralline algae in the seventies (Adey & McIntyre, 1973) since for many years the common occurrence of algal carbonates in non-tropical sediments was far to be a shared concept among geologists. More recently, some comprehensive books, reviews and a number of scientific papers on cool-water carbonates pointed out the importance of calcareous red algae as carbonate producer (among others: James & Clarke, 1997; Foster, 2001; Pedley & Carannante, 2006). In the nineties biologists started to quantify the growth of calcareous red algae by staining or other techniques, thus improving our knowledge at the organism level. However, modelling the response of the oceans to the global change require a quantification of the total carbonate and its mineralogy on regional scale. Large scale quantification of coralline algae in shelf carbonates is a challenge to the exploration of new methods of seafloor mapping, combined with analyses of sediment composition and mineralogy (Bracchi et al, 2009; Savini et al, 2009). References Adey W.H., McIntyre I.G. (1973). Crustose coralline algae: a re-evaluation in the geological sciences. - Geol. Soc. Am. Bull., 84: 883-904. Bracchi V., Caragnano A., Galimberti L., Basso D.(2009). Calcareous Algae and other Biogenic Carbonates in Selected Acoustic Facies of the Continental Shelf: Pontian Islands, Tyrrhenian Sea, Italy. – 6th Regional Symposium of the IFAA, Milan, 1-5 july 2009, Abstract book: 16. Broecker W.S., Takahashi T. (1977). Neutralization of fossil fuel CO2 by marine calcium carbonate. In: Andersen N. R., Malahoff A. (Eds.) The Fate of Fossil Fuel CO2 in the Oceans, Plenum, New York: 213– 248. Foster M. (2001). Rhodoliths: between rocks and soft places. - J. Phycol., 37: 659-667. Frankignoulle M., Canon C., Gattuso J.-P. (1994).Marine calcification as a source of carbon dioxide:positive feedback of increasing atmospheric CO2. - Limnol. Oceanogr., 39: 158–462. Guinotte J.M, Fabry V.J. (2008). Ocean acidification and its potential effects on marine ecosystems. In:Ostfeld R.S., Schlesinger W.H. (Eds.) The Year in Ecology and Conservation Biology 2008, Annals of the New York Academy of Sciences: 320–342. Hall-Spencer J.M., Rodolfo-Metalpa R., Martin S.,Ransome E., Fine M., Suzanne M., Turner S.M.,Sonia J., Rowley S.J., Tedesco D., Buia M.-C.(2008). Volcanic carbon dioxide vents show ecosystem effects of ocean acidification. - Nature 454: 96-99. James N., Clarke J.A.D. (1997). Cool water carbonates.- SEPM Special Publication 56, 432 pp. Kuffner I. B., Andersson A. J. et al. (2008). Decreased abundance of crustose coralline algae due to ocean acidification. - Nature Geoscience, 1(2): 114– 117. Morse J.W., Andreas J. Andersson A.J., Fred T. Mackenzie F.T. (2006). Initial responses of carbonate-rich shelf sediments to rising atmospheric pCO2 and ”ocean acidification”: role of high Mg-calcites. - Geochimica et Cosmochimica Acta, 70: 5814–5830. Pearson P.N., Palmer M.R. (2000). Atmospheric carbon dioxide concentrations over the past 60 million years. – Nature, 406: 695-699. Pedley H.M., Carannante G. (2006). Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls. - Geological Society, Special Publication 255, 384 pp. Royal Society (2005). Ocean acidification due to increasing atmospheric carbon dioxide. – The Royal Society Policy document 12/05, London, ISBN0854036172, Clyvedon Press Ltd, Cardiff,60 pp. Savini A., Bracchi V., Basso D., Corselli C., Pennetta M. (2009). Maërl facies distribution offshore Cilento Peninsula (Tyrrhenian Sea, Italy). - 6th Regional Symposium of the IFAA, Milan, 1-5 July 2009, Abstract book: 54.

Crustose coralline algae are a major benthic carbonate producer, especially in the temperate seas. The global change will induce ocean acidification, leading to dissolution of marine carbonates starting from aragonite and high-Mg calcite. The idea that corallines are an important element of the global carbon budget is widely accepted and many researches worldwide are devoted to understand their growth rate and physiological behaviour in the present-day marine environment and under conditions of lowered pH. Corallines are a topic for both life scientists and earth scientists, who are separated by their different cultural backgrounds and by the different temporal and spatial scale of their approach. The next scientific challenge is to overcome these difficulties: 1) by creating a common, shared language (systematic palaeontology vs. biology; limits of coralline palaeontology and usable diagnostic criteria; definitions of maërl, rhodoliths, prälines, coated grains, algal pavement, coralligène, crustose framework, etc.); 2) by linking observations and data obtained at the organism level to those obtained at the scale of geomorphologic units (such as a bay or a shelf). The results of some case-histories of large-scale quantification of coralline carbonate abundance in the present-day environment and in the past is reported, as a tool to improve our modelling the impact of the global change