Search Results (92)

The aim of this study is to determine the age and depositional environment of the Harami Formation through an integrated interpretation of XRF, ICP-MS, SEM-EDS, stable isotope, and radioactive isotope analysis results and findings of larger benthic foraminifera. Findings from the authors’ previous studies regarding the characteristics of larger benthic foraminifera were utilized; geochemical analysis results were obtained for the first time in this study. The mean ⁸⁷Sr/⁸⁶Sr values are generally consistent with the ages determined from the larger benthic foraminifera. The analysis results and Y/Ho values indicate that CaO is the dominant component, while negative Ce and positive Eu anomalies are indicative of a low-grade diagenetic effect. The absence of hydrothermal activity in the depositional environment and the proximity of the values to those of seawater are supported by the Y/Ho and Eu/Sm ratios. Similarly, to the larger benthic foraminifera content that indicates the Harami Formation was deposited in a shallow, oxic environment, the trace element ratios (V/Cr and V/V+Ni) and slightly negative Ce anomalies also support deposition in an oxic environment, while the Sr/Ba and Sr/Rb analysis results indicate a shallow marine environment. The analysis results further indicate that the depositional environment ranged from warm-temperate to arid conditions. A decrease in mean temperature is observed from the late Campanian to the early Maastrichtian, with an increase from the early Maastrichtian to the late Maastrichtian. Full article

The Jobos Bay National Estuarine Research Reserve (JBNERR) includes the largest bay on the southern coast of Puerto Rico. The reserve includes diverse habitats ranging from mangrove forests, shallow lagoons, seagrass beds, cays and coral reefs, with a broad range of environmental gradients between the populated coastal plain and the oligotrophic Caribbean Sea. As the only research reserve in the region, resource managers seek cost-effective and reliable processes to restore and promote ecosystem health in the reserve. Benthic foraminiferal assemblages are widely applied bioindicators for assessing coastal environments, notably coral reefs and seagrass ecosystems. This study evaluated the applicability of three indices, the FoRAM Index (FI), the Epiphytic FoRAM Index (FI′), and the Long vs. Short Life-Span Index (I_LS), to assess bayside and reef habitats bordering three cays of Jobos Bay. Surficial sediment samples were collected in 2018 and 2019. Environmental data included sediment composition (e.g., texture, total organic content) and water quality (e.g., nutrients and pH). From a total of 57 samples, 4671 individuals were counted, representing 35 genera. Cluster analysis based on genus-level relative abundances revealed four main groups: Dominant (>10%), Common (5–10%), Occasional (1–4%), and Rare (<1%). Dominant genera included Quinqueloculina (24%) and Amphistegina (18%). Common taxa included smaller rotaliids such as Rotorbinella (6%) and miliolids such as Pyrgo (5%). Twelve genera were occasional, including Triloculina (4%) and Elphidium (3%). Tests of 16 genera occurred rarely (<1%), including agglutinated taxa such as Textularia and stress-tolerant forms like Bolivina. In total, FI values ranged from 1.3 to 9.6, FI′ from 1.9 to 9.7, and I_LS from 0.5 to 30.6. Bayside samples scored generally lower compared to reef samples. In summary, foraminiferal assemblages and associated bioindices indicated that environmental conditions supported Foraminifera that host algal symbionts in the reef environments and the prevalence of macroalgae and seagrass in the bayside benthos. Full article

This study investigates the spatial variability of benthic foraminiferal assemblages across the shoreface–inner shelf transition of the Porto Pino coastal system (SW Sardinia, western Mediterranean). Porto Pino is a microtidal, wave-dominated embayment characterized by an environmental gradient extending from siliciclastic shoreface sands to mixed bioclastic sediments associated with the Posidonia oceanica meadow. A total of 33 sediment samples were analyzed for grain size, benthic foraminiferal assemblages, morphotypes and diversity indices. Cluster analysis and Principal Component Analysis (PCA) were used to investigate the spatial variability of the assemblages. Three main benthic foraminiferal assemblages were identified, each corresponding to a distinct benthic habitat: shallow unvegetated shoreface sands, a transitional zone near the upper limit of the P. oceanica meadow, and deeper mixed bioclastic sediments associated with its lower boundary. The distribution of the foraminiferal assemblage reflects the combined influence of hydrodynamic energy, substrate composition, water depth, and proximity to the meadow. Diversity indices indicate generally low-stress environmental conditions, whereas morphotype composition reflects changes in habitat structure and substrate characteristics along the shoreface–inner shelf gradient. These results demonstrate that benthic foraminifera effectively track environmental and sedimentological gradients in Mediterranean embayed systems and highlight their value for environmental reconstructions and biomonitoring applications. Full article

Benthic foraminifera are widely used as indicators of marine environmental conditions due to their sensitivity to ecological changes and their excellent preservation in sediments. In this study, benthic foraminiferal assemblages from a sediment core collected in the central Yellow Sea were investigated to document faunal composition and examine temporal changes since the Late Pleistocene. A total of 54 benthic foraminiferal species belonging to 33 genera, 25 families, seven orders, three classes, and one phylum were identified. Among them, 12 species are newly recorded in Korean waters, reflecting the current incompleteness of regional faunal inventories and the importance of detailed taxonomic studies. The assemblages exhibit distinct stratigraphic variations. The lower interval (>30 ka) is characterized by low-diversity assemblages dominated by taxa commonly associated with marginal marine environments. The middle interval (ca. 20–25 ka) shows the occurrence of taxa typically reported from boreal to subarctic environments, suggesting changes in environmental conditions during the Last Glacial Maximum. In contrast, the upper interval (Holocene) is marked by increased species diversity and the dominance of taxa characteristic of normal marine shelf environments. These assemblage changes are interpreted as reflecting long-term responses of benthic communities to sea-level fluctuations, sedimentary conditions, and regional oceanographic variability in the Yellow Sea. In particular, the development of fine-grained deposits in the Central Yellow Sea Mud (CYSM) and the establishment of stable marine shelf conditions during the Holocene likely played important roles in shaping benthic habitats. This study provides new baseline data on benthic foraminiferal diversity in the Yellow Sea and demonstrates the potential of these assemblages as useful, though indirect, indicators for reconstructing past environmental changes. The results highlight the importance of integrating detailed taxonomic analyses with stratigraphic records to improve our understanding of marine biodiversity and paleoenvironmental variability in marginal seas. Full article

Benthic foraminifera, single-cell marine organisms found worldwide, represent an important component of seabed ecosystems. Due to their sensitivity to environmental pollution, they are often used as bioindicators, providing an efficient tool in toxicity studies. Among the pollutants affecting marine coastal and estuarine environments, persistent flame retardants, such as polybrominated diphenyl ethers (PBDEs), are frequently found. Low-level exposure to BDE-47, a PBDE congener, is known to affect organismal development. In this framework, this study aims to assess the effects of BDE-47 exposure on benthic foraminifera from coastal marine environments. Foraminifera specimens belonging to the symbiont-bearing Peneroplidae family were sampled and exposed to two different BDE-47 concentrations for up to 48 h. Vitality indicators such as changes in pseudopodial activity, movement, reproduction, loss of symbiont algae, and occasional mortality events were monitored during the experiment. Exposure to BDE-47 induced alterations in pseudopodial activity, movement, reproduction, and symbiont retention, with the progressive loss of vitality and limited mortality at increasing exposure levels, highlighting the sensitivity of this species to BDE-47. These findings suggest the harmful repercussions of PBDE pollution on marine coastal ecosystems, affecting benthic organisms and potentially contributing to biomagnification processes within the food web, with possible implications for human health. Full article

Benthic foraminifera are effective indicators of heavy metal contamination in marine ecosystems. Traditional methods for benthic foraminiferal identification and biodiversity assessment rely predominantly on stereomicroscopic analysis. However, this approach is time-consuming, labor-intensive, and cannot effectively identify small or morphologically similar species. In this study, we aimed to enhance the utility of benthic foraminifera as bioindicators. To this end, we investigated the responses of benthic foraminiferal communities to varying concentrations of Cd under controlled laboratory conditions using both morphological assessments and metabarcoding analyses. Cd exposure reduced the abundance of benthic foraminifera. High Cd concentrations led to Cd enrichment in foraminiferal tests and altered the contents of other elements. Quinqueloculina, Ammonia, and Miliammina exhibited tolerance to Cd, whereas Parasorites and Ovammina were more sensitive. This study provides an effective approach for evaluating the short-term effects of heavy metal pollution on benthic foraminiferal communities. Full article

Benthic foraminifera are valuable bioindicators in modern and paleo-environmental studies due to their sensitivity to ecological changes. While sediment grain size is a fundamental factor structuring benthic habitats, its direct impact on benthic foraminifera remains poorly understood, as field studies are often complicated by covarying environmental parameters. To address this knowledge gap, we conducted a 14-week controlled laboratory culture experiment to investigate the biological response of a common benthic foraminifera Quinqueloculina seminula to different sediment grain sizes. Specimens were cultured in three distinct sediment grain size treatments (50, 150 and 250 μm), representing a gradient from fine to coarse sand. Our results demonstrate a clear and significant positive relationship between sediment grain size and the test size of Q. seminula. Furthermore, the species exhibited significant morphological plasticity, with the ratio of length/width increasing from 1.61 in fine sediment to 1.71 in coarse sediment. Individuals of Q. seminula in coarse sediment developed more elongate tests, while those in fine sediment maintained a more rounded morphology. This study provides the first experimental evidence that sediment grain size can drive significant changes in the size and morphology of Q. seminula. The observed phenotypic plasticity likely represents an adaptation to optimize locomotion and energetic allocation in different sedimentary environments. These findings confirmed the importance of sediment granulometry as a key control on foraminiferal biology and have important implications for the use of morphological data in paleoenvironmental reconstructions and modern biomonitoring. Full article

Coastal ecosystems are increasingly threatened by anthropogenic activities associated with tourism development and maritime traffic. This study evaluates the environmental quality of a coastal sector using an integrated approach combining sediment characteristics, heavy metal concentrations, and benthic foraminiferal assemblages. Nineteen surface sediments were collected and analyzed for trace metals using ICP-MS, while benthic foraminiferal assemblages were quantified, and ecological indices were calculated. Results reveal elevated concentrations of trace metals at coastal stations, closely associated with high TOM and fine-grained sediments, indicating significant anthropogenic inputs. These stations are characterized by low species richness, reduced Shannon diversity, high dominance, low living foraminiferal percentages, high malformed individuals, and markedly low FoRAM values, reflecting stressed environmental conditions. Opportunistic taxa such as Ammonia tepida dominate impacted sites, whereas sensitive carbonate-producing taxa (Quinqueloculina lamarckiana, Coscinospira hemprichii, Elphidium striatopunctatum, Elphidium crispum) prevail at less disturbed stations. Multivariate analyses clearly separate polluted coastal stations from relatively unimpacted offshore sites. The combined geochemical and biological evidence demonstrates that tourism-related activities and ship effluents exert a strong negative influence on benthic ecosystems. Benthic foraminifera, together with heavy metals, provide an effective and sensitive tool for assessing anthropogenic impacts and coral reef health for sustainable coastal management of Safaga Bay. Full article

The integration of sedimentological and micropaleontological data in the Zanclean and Gelasian shallow-marine deposits of the Crotone Basin (southern Italy) has allowed documentation of meter-to-decameter-scale high-frequency sequences bounded by wave-ravinement surfaces (WRSs), which in turn are composed of meter-scale sedimentological cycles, referred to as bedsets. In contrast to high-frequency sequences, bedsets have a more subtle appearance, and their boundaries exhibit limited lateral extent compared to WRSs. Moreover, the micropaleontological analyses have allowed the definition of three parameters: distal/proximal (D/P: ratio between distal and proximal benthic foraminifera); fragmentation (Fr: percentage of fragmentation of benthic foraminifera); and P/B (ratio between planktonic and benthic foraminifera). In particular, the D/P and Fr allow to recognize uncertainty intervals containing the maximum flooding surface (MFS) of high-frequency sequences, whereas the P/B documents water-depth changes. Unlike in high-frequency sequences, the D/P, Fr and P/B parameters usually do not show appreciable variations associated with bedsets, confirming that the latter are unrelated to shoreline shifts and water-depth variations, but are rather controlled by minor sediment supply and/or wave regime changes. However, in rare cases, the micropaleontological parameters seem to indicate that subtle transgressive-regressive trends and water-depth variations can also be associated with bedset deposition, alluding to a ‘grey area’ of transition between high-frequency sequences of very small scale and bedsets. Further research is, therefore, needed to constrain the boundary between sedimentology and stratigraphy. Full article

The Santos Estuarine System, one of the most anthropogenically impacted coastal regions in Brazil, was studied using benthic foraminiferal assemblages to determine four distinct stages of organic pollution. Predictive models combined with the Ecological Quality Status (EcoQs) index were applied to relate pollution stages to abiotic parameters (total organic carbon, mud content, and salinity variability) and organic contaminants, including aliphatic (AHs) and aromatic hydrocarbons (PAHs), linear alkylbenzenes (LABs), and coprostanol. The pollution gradient ranged from low (São Vicente Channel and Santos Bay, characterized by Ammonia tepida and medium coprostanol concentrations), to moderate (Santos Channel, with Bulimina elongata and Triloculina sp.1), high (Bertioga Channel, showing Cribroelphidium poeyanum, Paratrochammina sp.1, high levels of LABs, and TOC), and severe (Upper Estuary, marked by Ammonia sp.1 and high concentrations of PAHs and coprostanol). A linear discriminant analysis (LDA) demonstrated an overall accuracy of 70%, suggesting that the discriminant model performs reasonably well in predicting the predictive ability of foraminifera species to distinguish between areas with varying pollution status based on organic pollutants. Also, the potential use of the EcoQs index in assessing the environmental quality of a subtropical estuary subjected to organic pollution was demonstrated. Full article

In recent decades, the Mediterranean Sea has been experiencing faunal changes associated with the impact of biological invasions resulting from the influx of invasive alien species (IAS). During the CNR-ISMAR Carg0222 oceanographic cruise, Mimosina affinis, a benthic foraminifera species of Indo-Pacific origin previously reported in more eastern sectors of the Mediterranean, was detected in the Tyrrhenian Sea, at the seafloor off the Italian coast. The study of benthic foraminiferal assemblages, conducted along with sedimentological analysis of seafloor deposits, allowed to reconstruct the distribution of Mimosina affinis in the investigated area and define its relationship with seabed characteristics. The species is commonly found in samples collected at a water depth not shallower than nine metres, showing a preference for silty fine sand sediments. The abundance of the species, in terms of relative abundance, is higher in biocoenoses than in thanatocoenoses, suggesting that the species is established and actively spreading in the studied area. Full article

Foraminifera are unicellular protists with external shells (tests) that may be calcareous (porcelaneous or hyaline), agglutinated, or organic-walled. Their test morphology and as-assemblage composition closely track environmental forcing, making them robust bioindicators of marine change. Documenting morphology and faunal composition is therefore essential for interpreting species distributions and their paleoenvironmental significance. Here we provide a systematic account of foraminiferal assemblages from core sediments in the Ulleung Basin, East Sea (Sea of Japan), with accompanying imagery and diagnostic notes. We identify 47 species across 32 genera and 20 families, including 15 planktic and 32 benthic taxa. Seven species are newly recorded for Korean waters: the planktic Tenuitellita fleisheri and Neogloboquadrina atlantica subsp. praeatlantica, and the benthic Islandiella algida, Uvigerina asperula, Pseudonodosaria aequalis, Pseudonodosaria obtusissima, and Astacolus crepidula. The presence of these previously unreported taxa likely reflects historical under-sampling and limited taxonomic emphasis in the region, coupled with the geomorphological challenges of the Ulleung Basin. In addition, the recognition of five distinct morphotypes of Neogloboquadrina pachyderma points to substantial past environmental variability in the basin. Continued evaluation of morphological diversity and distributional patterns in these assemblages will support stratigraphic applications and reconstruction of past marine environments in the East Sea by clarifying depth-wise faunal turnovers that likely record a composite signal of hydrographic variability overprinted by episodic seismic disturbance and slope current reworking. Full article

Lake Salda in Türkiye serves as a valuable Earth analog for studies of the properties of Mars due to its mineralogical and microbiological similarities to Jezero Crater on Mars. This study investigated the role of sulfate-reducing bacteria (SRB) enrichment culture isolated from Lake Salda on the microbiologically influenced corrosion (MIC) of an aluminum alloy (AA7075) using electrochemical, microbiological, molecular, and spectroscopic methods. Potentiodynamic polarization (PDP) tests confirmed SRB-enriched biofilm significantly accelerated corrosion. Fourier Transformed Infrared Spectroscopy (FTIR) further distinguished the control and biotic surfaces, showing the replacement of a 980 cm⁻¹ polysaccharide band with a 1075 cm⁻¹ cyclic polysaccharide vibration in SRB-colonized coupons. This spectral transition reflects biofilm maturation and EPS accumulation, providing molecular evidence for SRB-driven MIC. Molecular analysis identified Proteobacteria and Firmicutes as dominant phyla, and Desulfofustis limnaeus was detected in Lake Salda for the first time. Moreover, benthic foraminifera and ostracods were observed, some with morphological anomalies. These results provide mechanistic insight into the biochemical and electrochemical interactions driving SRB-induced corrosion, highlighting Lake Salda’s importance for studying microbial–material interactions in extreme environments. Full article

Amphistegina lobifera, a symbiont-bearing benthic foraminifera native to the Indo-Pacific, is expanding its distribution range in the Mediterranean Sea due to ysian migration through the Suez Canal. This study investigates the colonization dynamics and ecological impact of A. lobifera on Pantelleria Island, which is located in the Central Mediterranean. Nine samples were collected from various substrates at different depths (−4 to −20 m) and analysed for composition, abundance, and ecological diversity. Results reveal a significant dominance of A. lobifera, especially in shallow unvegetated substrates, with relative abundances exceeding 50%. Conversely, more vegetated substrates host more diverse and balanced assemblages. Diversity indices are consistently lower where A. lobifera is dominant, indicating reduced biodiversity. Comparison with similar studies in Malta, Linosa, and Corfu confirms a 20% relative abundance threshold for A. lobifera as indicative of potential ecological imbalance. The results suggest that it represents a growing threat to native microbenthic biodiversity and reinforce its usefulness as a bioindicator species. Pantelleria represents a key transition zone for monitoring the dynamics of invasive species in the Mediterranean, and this study highlights the urgent need for long-term surveillance of benthic biodiversity. Full article

The rich Eocene larger benthic foraminiferal (LBF) assemblages in the vicinity of Verona have long been well known. However, they are described in detail only from the Ypresian to Bartonian interval. Here, we present the results of our morphometrically based study of Priabonian LBF. The lowermost part of the succession, just above the uppermost occurrence of giant Nummulites (N. biedai), outcrops at Monte Cavro and contains Heterostegina reticulata multifida and Nummulites hormoensis as major constituents. These taxa clearly determine the earliest Priabonian Shallow Benthic Zone (SBZ) 18C. Slightly younger strata can be analyzed in the other three studied exposures on the northern side of Castel San Felice. These beds already represent the early Priabonian SBZ 19A Zone based on the first appearing Spiroclypeus sirottii and the presence of Heterostegina reticulata mossanensis and Nummulites fabianii (replacing H. r. multifida and N. hormoensis, respectively). The most abundant LBF in these beds are the very diverse and well-preserved orthophragmines represented the families Discocyclinidae (genera Discocyclina and Nemkovella) and Orbitoclypeidae (genera Orbitoclypeus and Asterocyclina). They determine the Orthophragmine Zone (OZ) 14. The distinction of six species of the genus Discocyclina (especially that of D. euaensis from D. dispansa) is discussed in detail. The exposures around Castel San Felice are considered as key localities for the SBZ 19A and OZ 14 Zones, containing their key LBF assemblages. Consistently, both orthophragmine and LBF range charts for the late Lutetian to Priabonian are updated. Full article