Comparative high-resolution chemostratigraphy of the Bonarelli Level from the reference Bottaccione section (Umbria-Marche Apennines) and from an equivalent section in NW Sicily: Consistent and contrasting responses to the OAE2.

The Bonarelli Level (BL) from the upper Cenomanian portion of the reference Bottaccione section (central Italy) is characterized by the presence of black shales containing high TOC concentrations (up to 17%) and amounts of CaCO3 near to zero. In the absence of carbonate and, consequently, of relative carbon- and oxygen- isotopic data, the elemental geochemistry revealed to be a very useful tool to obtain information about the palaeoclimatic and palaeoceanographic evolution of the Tethys Ocean during the OAE2. Based on several geochemical proxies (Rb, V, Ni, Cr, Si, Ba), the BL is interpreted as a high-productivity event driven by increasingly warm and humid climatic conditions promoting an accelerated hydrological cycle. The enrichment factors of peculiar trace metals (Zn, Cd, Pb, Sb, Mo, U) provide further insight about the H2S activity at the seafloor during the organic-rich sediment deposition and permitted us to evaluate the use of Ba as palaeoproductivity tracer in conditions of high rate of sulphate reduction. By comparing geochemical records from the reference Bottaccione section (central Italy) with those previously obtained for the coeval Calabianca section (northwestern Sicily), different degrees of oceanic anoxia were delineated and ascribed to different abundance and type (degradable or refractory) of organic matter, which are limiting factors in the bacterial sulphate reduction reactions and in subsequent euxinic conditions at seafloor in the Tethys realm. Based on a ciclostratigraphic approach, consistent fluctuations at 100 kyr scale in the chemostratigraphic signals from the two sections are inferred to be expression of a strong orbital-climatic forcing driving changes in the oceanic environment during the BL deposition

Assessing the effect of mercury pollution on cultured benthic foraminifera community using morphological and eDNA metabarcoding approaches

none14sìMercury (Hg) is a highly toxic element for living organisms and is known to bioaccumulate and biomagnify. Here, we analyze the response of benthic foraminifera communities cultured in mesocosm and exposed to different concentrations of Hg. Standard morphological analyses and environmental DNA metabarcoding show evidence that Hg pollution has detrimental effects on benthic foraminifera. The molecular analysis provides a more complete view of foraminiferal communities including the soft-walled single-chambered monothalamiids and small-sized hard-shelled rotaliids and textulariids than the morphological one. Among these taxa that are typically overlooked in morphological studies we found potential bioindicators of Hg pollution. The mesocosm approach proves to be an effective method to study benthic foraminiferal responses to various types and concentrations of pollutants over time. This study further supports foraminiferal metabarcoding as a complementary and/or alternative method to standard biomonitoring program based on the morphological identification of species communities.openFrontalini, Fabrizio; Greco, Mattia; Di Bella, Letizia; Lejzerowicz, Franck; Reo, Emanuela; Caruso, Antonio; Cosentino, Claudia; Maccotta, Antonella; Scopelliti, Giovanna; Nardelli, Maria Pia; Losada, Maria Teresa; Armynot du Châtelet, Eric; Coccioni, Rodolfo; Pawlowski, JanFrontalini, Fabrizio; Greco, Mattia; Di Bella, Letizia; Lejzerowicz, Franck; Reo, Emanuela; Caruso, Antonio; Cosentino, Claudia; Maccotta, Antonella; Scopelliti, Giovanna; Nardelli, Maria Pia; Losada, Maria Teresa; Armynot du Châtelet, Eric; Coccioni, Rodolfo; Pawlowski, Ja

Benthic foraminiferal ultrastructural alteration induced by heavy metals

Heavy metals are known to cause deleterious effects on biota because of their toxicity, persistence and bioaccumulation. Here, we briefly document the ultrastructural changes observed in the miliolid foraminifer Pseudotriloculina rotunda (d\u27Orbigny in Schlumberger, 1893) and in the perforate calcareous species Ammonia parkinsoniana (d\u27Orbigny, 1839) induced by exposure to one of three heavy metals (zinc, lead, or mercury). The exposure of these two benthic foraminiferal species to the selected heavy metals appears to promote cytological alterations and organelle degeneration. These alterations include a thickening of the inner organic lining, an increase in number and size of lipid droplets, mitochondrial degeneration, and degradation vacuoles and residual body proliferation. Some of these alterations, including the thickening of the inner organic lining and the proliferation of lipids, might represent defense mechanisms against heavy metal-induced stress

An extraterrestrial trigger for the Early Cretaceous massive volcanism? Evidence from the paleo-Tethys Ocean

The Early Cretaceous Greater Ontong Java Event in the Pacific Ocean may have covered ca. 1% of the Earth's surface with volcanism. It has puzzled scientists trying to explain its origin by several mechanisms possible on Earth, leading others to propose an extraterrestrial trigger to explain this event. A large oceanic extraterrestrial impact causing such voluminous volcanism may have traces of its distal ejecta in sedimentary rocks around the basin, including the paleo-Tethys Ocean which was then contiguous with the Pacific Ocean. The contemporaneous marine sequence at central Italy, containing the sedimentary expression of a global oceanic anoxic event (OAE1a), may have recorded such ocurrence as indicated by two stratigraphic intervals with 187Os/188Os indicative of meteoritic influence. Here we show, for the first time, that platinum group element abundances and inter-element ratios in this paleo-Tethyan marine sequence provide no evidence for an extraterrestrial trigger for the Early Cretaceous massive volcanism

Bottom-Water Conditions in a Marine Basin after the Cretaceous–Paleogene Impact Event: Timing the Recovery of Oxygen Levels and Productivity

An ultra-high-resolution analysis of major and trace element contents from the Cretaceous–Paleogene boundary interval in the Caravaca section, southeast Spain, reveals a quick recovery of depositional conditions after the impact event. Enrichment/depletion profiles of redox sensitive elements indicate significant geochemical anomalies just within the boundary ejecta layer, supporting an instantaneous recovery –some 102 years– of pre-impact conditions in terms of oxygenation. Geochemical redox proxies point to oxygen levels comparable to those at the end of the Cretaceous shortly after impact, which is further evidenced by the contemporary macrobenthic colonization of opportunistic tracemakers. Recovery of the oxygen conditions was therefore several orders shorter than traditional proposals (104–105 years), suggesting a probable rapid recovery of deep-sea ecosystems at bottom and in intermediate waters.This research was supported by Projects CGL2009-07603, CGL2008-03007, CGL2012-33281 and CGL2012-32659 (Secretaría de Estado de I+D+I, Spain), Projects RNM-3715 and RNM 05212, and Research Groups RNM-178 and 0179 (Junta de Andalucía)

Response of Benthic Foraminifera to organic matter quantity and quality and bioavailable concentrations of metals in Aveiro Lagoon (Portugal)

This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to metals enrichment.CNPq [401803/2010-4]; [PEst-OE/CTE/UI4035/2014]info:eu-repo/semantics/publishedVersio