During the mid-Cretaceous, the Earth experienced several environmental perturbations, including an extremely warm climate and Oceanic Anoxic Events (OAEs). Submarine volcanic episodes associated with ...formation of large igneous provinces (LIPs) may have triggered these perturbations. The osmium isotopic ratio (
Os/
Os) is a suitable proxy for tracing hydrothermal activity associated with the LIPs formation, but
Os/
Os data from the mid-Cretaceous are limited to short time intervals. Here we provide a continuous high-resolution marine
Os/
Os record covering all mid-Cretaceous OAEs. Several OAEs (OAE1a, Wezel and Fallot events, and OAE2) correspond to unradiogenic
Os/
Os shifts, suggesting that they were triggered by massive submarine volcanic episodes. However, minor OAEs (OAE1c and OAE1d), which do not show pronounced unradiogenic
Os/
Os shifts, were likely caused by enhanced monsoonal activity. Because the subaerial LIPs volcanic episodes and Circum-Pacific volcanism correspond to the highest temperature and pCO
during the mid-Cretaceous, they may have caused the hot mid-Cretaceous climate.
Abstract The Aptian–Albian boundary is marked by one of the major oceanic perturbations during the Cretaceous, called Oceanic Anoxic Event (OAE) 1b. Extensive volcanic episodes at the Southern ...Kerguelen Plateau has been suggested as the trigger of OAE1b, but compelling evidence remains lacking. Here, we reconstructed the temporal variations of marine Os isotopic ratios across the Aptian–Albian boundary in the Tethyan and Pacific pelagic sedimentary records to elucidate the causal links between OAE1b, the biotic turnover, and volcanic episodes. Our new Os isotopic records show two negative spikes that correlate with a period of planktonic foraminiferal turnover across the Aptian–Albian boundary during OAE1b and suggest multiple submarine volcanic events. By comparing our Os isotopic profile with carbon isotopic compositions of carbonate, CaCO 3 content, and the relative abundances of agglutinated foraminifera, we conclude that ocean acidification caused by the massive release of CO 2 through extensive volcanic episodes could have promoted the major planktonic foraminiferal turnover during OAE1b.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•We applied the diversity index Exp(H’bc) based on living benthic foraminifera to assess EcoQs in Italian transitional waters.•Index values were significantly correlated with environmental ...parameters.•The foraminiferal method provides a reliable assessment of EcoQs.•Benthic foraminifera are a relevant complement to benthic macrofauna to assess EcoQs.
Estuaries, lagoons and lakes, identified as transitional waters (TWs), are fragile ecotones at the interface between terrestrial and marine ecosystems. The assessment of their Ecological Quality status (EcoQ), required by marine legislations, is rather uncertain when based on traditional benthic macrofaunal indices. This study proposes to assess the EcoQ of marine waters using the diversity index Exp(H’bc) based on living benthic foraminifera. By testing this method on datasets from five Italian TWs, we showed that EcoQ’s assessment based on foraminifera reflected changes in environmental conditions. Benthic foraminifera highlighted the degradation of most, if not all, study sites, ranking most of the TWs in “Moderate” to “Bad” EcoQs. Although the assessment of EcoQs estimated from diversity indices was similar when based on benthic foraminifera or macrofauna, discrepancies occurred if diversity index calculated on foraminifera and sensitivity-based indices applied on macrofauna were compared. Our results demonstrated that the Exp(H’bc) index based on living benthic foraminifera is a promising approach to assess EcoQs. Finally, we argue that benthic foraminifera, for their preservation potential as fossil within sediment, are a reliable option to define reference conditions and targets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The Turonian age (~ 90-94 Ma) was the hottest geological interval in the Cretaceous and also marked by the K3 event, a pronounced enrichment of
He in pelagic sediments (i.e., massive input of ...extraterrestrial materials). Here, we present Os isotopic (
Os/
Os) and platinum group element (PGE) data from Turonian sedimentary records. After a sharp unradiogenic shift during the end-Cenomanian oceanic anoxic event 2, the
Os/
Os ratios declined continuously throughout the Turonian, which could be ascribed to the formations of several large igneous provinces (LIPs). Because the interval with the most unradiogenic
Os/
Os ratios (i.e., enhanced LIP volcanism) does not correspond to the warmest interval during the mid-Cretaceous, additional sources of CO
, such as subduction zone volcanism or the kimberlite formation, may explain the Cretaceous Thermal Maximum. As Os isotope ratios do not show any sharp unradiogenic shifts and PGE concentrations do not exhibit a pronounced enrichment, an influx of fine-grained cosmic dust to the Earth's surface, possibly from the long-period comet showers, can be inferred at the time of the
He enrichment during the mid-Turonian K3 event. Our findings highlight the different behaviors of
He and PGE information in the sedimentary rocks during the input of fined-grained extraterrestrial materials.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Since the 1950s, numerous studies have demonstrated the value of benthic foraminifera in detecting ecosystem contamination. The interest in benthic foraminifera has partly been driven by government ...policies and programs aimed at developing suitable, non-invasive bioindicators of marine environmental quality. This paper accomplishes two things: it reveals that Italian experience has significantly contributed to the advancement of our understanding of this topic and summarizes the most important results that have served to greatly improve our knowledge in this field. Although many issues are still a matter of debate, since it is difficult to separate natural vs human-induced pollution and a foraminiferal protocol has not yet been produced, foraminifera have been proven to be successful candidates as part of an integrated monitoring program.
Depuis les années 1950, de nombreuses études ont démontré la qualité des foraminifères benthiques pour mettre en évidence les écosystèmes contaminés. Cet intérêt pour les foraminifères benthiques a en partie été guidé par les exigences gouvernementales qui demandaient des indicateurs biologiques de la qualité des environnements marins non invasifs. Les deux objectifs de cet article sont de mettre en évidence que l’expérience italienne a significativement contribué à l’avancement de notre compréhension de ce sujet et de résumer les résultats les plus importants qui nous ont conduit à l’amélioration de cette connaissance. Bien que de nombreux travaux soient toujours des sujets de débats sur le fait qu’il est difficile de séparer les contraintes naturelles des contraintes anthropiques et qu’un protocole standard d’analyse des foraminifères n’a toujours pas été proposé, les foraminifères ont largement prouvé leur valeur pour être intégrés dans les programs de suivi environnementaux.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The Monastir Bay is one of the most important resources of marine diversity in Tunisia. The marine biodiversity quality of its coastal area has been however affected by several industrial, fishing ...and fish-farming activities. A multidisciplinary characterization based on geochemical analyses of sediment and benthic foraminifera was undertaken to evaluate the environmental quality of marine sediments. The geochemical data combined with the statistical results suggests an overall contamination of sediment mainly by Zn, Ni and Cu and the identification of an area particularly polluted. This zone corresponds to the area in front of the Khniss drain that has been historically affected by the presence of multiple sources of pollution. The site is also characterized by a poorly diversified benthic foraminiferal assemblage, reflecting the poor environmental conditions. Some species such as Quinqueloculina seminula and Vertebralina striata appear to be positively related to EF and might be considered as tolerant taxa to pollution in the Monastir Bay. The present study further reinforces the application of benthic foraminifera as proxies of pollution and as bioindicators of the environmental quality and represents among the first contributions in a Tunisian coastal marine area based on living benthic foraminifera as bioindicators.
•Monastir Bay is one of the most important resources of marine species in Tunisia.•Trace metals pollution has detrimental effects on benthic foraminifera assemblages.•Geochemical and foraminiferal analyses reveal deteriorated conditions.•Foraminiferal taxa have the potential to be used as trace metals bioindicators.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Middle Eocene Climatic Optimum (MECO) is a global warming event that occurred at about 40 Ma. In comparison to the most known global warming events of the Paleogene, the MECO has some peculiar ...features that make its interpretation controversial. The main peculiarities of the MECO are a duration of ~500 kyr and a carbon isotope signature that varies from site to site. Here we present new carbon and oxygen stable isotopes records (δ
C and δ
O) from three foraminiferal genera dwelling at different depths throughout the water column and the sea bottom during the middle Eocene, from eastern Turkey. We document that the MECO is related to major oceanographic and climatic changes in the Neo-Tethys and also in other oceanic basins. The carbon isotope signature of the MECO is difficult to interpret because it is highly variable from site to site. We hypothesize that such δ
C signature indicates highly unstable oceanographic and carbon cycle conditions, which may have been forced by the coincidence between a 400 kyr and a 2.4 Myr orbital eccentricity minimum. Such forcing has been also suggested for the Cretaceous Oceanic Anoxic Events, which resemble the MECO event more than the Cenozoic hyperthermals.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This study investigated the environmental quality of the Bizerte Lagoon (Tunisia) through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal ...analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM), acid volatile sulfides (AVS), chlorophyll a, CaCO3, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal assemblages were dominated by species such as A. parkinsoniana (20-91%), Bolivina striatula (<40%), Hopkinsina atlantica (<17%), and Bolivina ordinaria (<15%) that cannot be considered typical of impacted coastal lagoons both in Mediterranean and northeast Atlantic regions. The results of this work suggest that Bizerte Lagoon is a unique setting. This lagoon is populated by typical marine species that invaded this ecosystem, attracted not only by the prevailing favorable environmental conditions but also by the abundance and quality of food. The results indicate that the metal pollution found in some areas have a negative impact on the assemblages of foraminifera. At present, however, this negative impact is not highly alarming.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study was conducted in Lake Varano (southern Italy) in order to determine the environmental parameters that influence nematode taxonomic and functional diversity and how they influence them, and ...to classify for the first time the ecological quality status of a transitional environment. The general composition and level of taxonomic diversity were comparable with those reported for transitional environments worldwide. Principal component analysis revealed that the main environmental factors controlling the assemblages in terms of both composition and biological traits were grain size, organic matter, pollution load index and, only secondarily, salinity. Molgolaimus allgeni, Terschellingia longicaudata and Leptolaimus luridus showed higher values in relation to silt, organic matter and pollution load index, while Axonolaimus caudostriatus, Odontophora wieseri, Paramonhystera pellucida and Paracanthonchus longicaudatus showed higher values in relation to the redox potential and sand percentage. Salinity was detected as an influencing parameter only secondarily and particularly for Calomicrolaimus honestus, Daptonema normandicum, Thalassomonhystera parva and Sabatieria pulchra. With respect to functional traits, the trophic groups seemed to be mainly related to sediment type, which is in turn reflected by the nature of the available food. The maturity index, as well as c-p classes, did not always permit a clear interpretation of the interaction between anthropogenic and natural factors. However, the greater influence of the San Antonino and San Francesco Canals was perfectly revealed by the nematode assemblage. In accordance with the current ecological quality classes, Lake Varano can mainly be classified as having good to poor ecological quality status.
Plastic has become one of the most ubiquitous and environmentally threatening sources of pollution in the Anthropocene. Beyond the conspicuous visual impact and physical damages, plastics both carry ...and release a cocktail of harmful chemicals, such as monomers, additives and persistent organic pollutants. Here we show through a review of the scientific literature dealing with both plastic pollution and benthic foraminifera (Rhizaria), that despite their critical roles in the structure and function of benthic ecosystems, only 0.4% of studies have investigated the effects of micro- and nano-plastics on this group. Consequently, we urge to consider benthic foraminifera in plastic pollution studies via a tentative roadmap that includes (i) the use of their biological, physiological and behavioral responses that may unveil the effects of microplastics and nanoplastics and (ii) the evaluation of the indicative value of foraminiferal species to serve as proxies for the degree of pollution. This appears particularly timely in the context of the development of management strategies to restore coastal ecosystems.
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•Foraminifera are exposed to plastic via inclusion in the test, ingestion and leachates.•We found only four studies on the impact of MPs and NPs on foraminifera.•Plastics alter foraminiferal feeding behavior and induce oxidative stress.•Methodological heterogeneity between studies hampers comparisons.•We suggest a roadmap to address the potential hazard of plastic on foraminifera.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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