Ammonia Parkinsoniana Research Articles

Benthic foraminiferal ultrastructural alteration induced by heavy metals

Abstract 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'Orbigny in Schlumberger, 1893) and in the perforate calcareous species Ammonia parkinsoniana (d'Orbigny, 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.

Paleoenvironmental evolution based on benthic foraminifera biofacies of the Paraíba do Sul Deltaic Complex, eastern Brazil

The paleoecology and distribution of benthic foraminiferal assemblages were analyzed in the core 2-MU-1-RJ well, drilled in the Paraíba do Sul Deltaic Complex, Rio de Janeiro (Brazil). An abundant assemblage was found in the upper portion of the well core, inferred to be pleistocenic deposits. The coastal dynamic was recognized from five biofacies based on clusters, the Planktonic/Benthic (P/B) ratios and indicator species distribution in the core. Several biofacies were identified along the core depending on the species dominance. From the bottom to the top of the core, the biofacies succession represents the environmental changes in the coastal area associated to sea-level oscillations. The biofacies ABP dominated by Ammonia parkinsoniana and Bolivina spp. and Pararotalia cananeiaensis represents an inner shelf environment; biofacies QP dominated by shelf miliolids species; biofacies PGH, dominated by P. cananeiaensis, Gavelinopsis praegeri, and Hanzawaia nitidula, represents the estuary complex with middle or outer shelf influence; biofacies QL represents hypersaline waters dominated by lagoonal miliolids; and biofacies HP characterized by Haynesina germanica and P. cananeiaensis is associated with paralic environments. Marine ingressions are recorded and those biofacies show the pleistocenic coastal hydrodinamic in the deltaic complex. The foraminiferal biofacies contribute with detailed information to sedimentary facies previously characterized in the study area by the reconstruction of paleoenvironment succession.

Foraminíferos e Tecamebas Bentônicos do Estuário do Rio Godineau, Golfo de Paria, Ilha de Trinidad

In the Godineau River Estuary, located in Trinidad Island (off the northeast coast of Venezuela), were found 114 taxa of foraminifera and 17 of thecamoebians in the dead fauna. Most of the identified foraminiferal species were rare because they were transported from the Gulf of Paria to this estuary. The autochthonous foraminiferal assemblage was represented by several tropical estuarine species such as Ammonia tepida, Ammotium salsum, Arenoparrella mexicana, Cribroelphidium excavatum, Ammonia parkinsoniana, Haplophragmoides wilberti, Miliammina fusca and Ammotium cassis. The thecamoebians assemblages, found in the inner part of this estuary, were dominated by Cyclopyxis spp., Centropyxis spp., Difflugia corona and Difflugia urceolata. The relative abundance of the main species of foraminifera and thecamoebians were analyzed through Q-mode and R-mode cluster analyses. Statistical results revealed the presence of three different environments in the Godineau River Estuary related to different hydrodynamic conditions and more or less oceanic or fluvial influence. The first sector represents the most confined region of the estuary and was mainly composed by agglutinated foraminifera together with thecamoebians. The second sector was located in the middle part of the estuary and was associated with the presence of brackish waters. The third sector denotes the outermost part of the estuary characterized by the greatest hydrodynamic activity and highest oceanic influence within the estuary. This sector was marked by the occurrence of a large number typical-marine foraminifera species.

Foraminíferos e Tecamebas Bentônicos do Estuário do Rio Godineau, Golfo de Paria, Ilha de Trinidad

In the Godineau River Estuary, located in Trinidad Island (off the northeast coast of Venezuela), were found 114 taxa of foraminifera and 17 of thecamoebians in the dead fauna. Most of the identified foraminiferal species were rare because they were transported from the Gulf of Paria to this estuary. The autochthonous foraminiferal assemblage was represented by several tropical estuarine species such as Ammonia tepida, Ammotium salsum, Arenoparrella mexicana, Cribroelphidium excavatum, Ammonia parkinsoniana, Haplophragmoides wilberti, Miliammina fusca and Ammotium cassis. The thecamoebians assemblages, found in the inner part of this estuary, were dominated by Cyclopyxis spp., Centropyxis spp., Difflugia corona and Difflugia urceolata. The relative abundance of the main species of foraminifera and thecamoebians were analyzed through Q-mode and R-mode cluster analyses. Statistical results revealed the presence of three different environments in the Godineau River Estuary related to different hydrodynamic conditions and more or less oceanic or fluvial influence. The first sector represents the most confined region of the estuary and was mainly composed by agglutinated foraminifera together with thecamoebians. The second sector was located in the middle part of the estuary and was associated with the presence of brackish waters. The third sector denotes the outermost part of the estuary characterized by the greatest hydrodynamic activity and highest oceanic influence within the estuary. This sector was marked by the occurrence of a large number typical-marine foraminifera species.

Benthic foraminifera as a key to delta evolution: Acase study from the late Holocene succession of the Po River Delta

Benthic foraminifera from stratigraphically expanded, late Quaternary prodelta successions of the Po Delta plain reveal small-scale paleoenvironmental variations within lithologically homogeneous deposits formed under conditions of rapid sedimentation (ca. 6 cm/yr). A detailed paleoenvironmental reconstruction was obtained comparing benthic foraminifera with shallow-water assemblages from the modern Po Delta. The integration with sediment geochemistry and radiocarbon dates was also tested to detect short time-scale delta dynamics controlled by autogenic factors. Core 7 records the development of an inner-shelf environment (interval A), replaced by a prodelta with strong fluvial influence, shown by the sharp increase in Ammonia tepida and Ammonia parkinsoniana (interval B). These taxa are replaced by Aubignyna perlucida (interval C) which indicates a major mouth shift (Ficarolo avulsion). Subsequent abrupt increases in A. tepida and A. parkinsoniana document a step-like progradation of the Po di Goro delta lobe (intervals D and E). In the seaward Core 1, possible minor mouth shifts are recorded by a sharp increase in A. tepida and A. parkinsoniana, paralleled by Cr/Al2O3 depletion. The upper portion of both prodelta successions includes stacked flood layers formed near the river mouth, as indicated by scarce A. tepida and A. parkinsoniana.

BENTHIC FORAMINIFERAL PROXIES FOR POLLUTION MONITORING IN AL-MUKALLA COASTAL AREA, HADRAMOUT GOVERNATE, REPUBLIC OF YEMEN

The coastal waters of Al-Mukalla, Hadramout Governate, Republic of Yemen, receive considerable amounts of treated and untreated domestic and industrial effluents, which carry a variety of contaminants including heavy metals. We surveyed benthic foraminiferal assemblages as potential indicators for pollution and collected geochemical, sedimentological and water-quality data. Cluster and canonical correspondence analyses delineated three areas: unpolluted areas east and west of Al-Mukalla harbor (biofacies I), a moderately polluted area in and around the harbor (biofacies II), and a highly polluted site within the main harbor (biofacies III). Biofacies I is characterized by sandy sediments with moderate proportions of CaCO 3 , low total organic matter and low heavy metal concentrations. This biofacies is characterized by pollution-sensitive smaller species ( Ammonia parkinsoniana , Discorbinella bertheloti and Pararotalia nipponica ). Biofacies II includes sites exposed to southwest monsoon winds, which are characterized by coarse sand relatively rich in CaCO 3 , as well as more protected sites that are somewhat more muddy, with somewhat higher concentrations of organic matter and heavy metals. Foraminiferal assemblages include larger taxa ( Amphistegina lessonii , Peneroplis pertusus , Neorotalia calcar , and Sorites orbiculus ), as well as smaller species ( Elphidium crispum , Glabratella patelliformis , and Discorbis turbo ). Biofacies III is found at a relatively muddy site that is rich in organic matter and heavy metals, particularly Cu and Zn. The foraminiferal assemblage is characterized by pollution-tolerant species, including Ammonia tepida , E. advenum , E. gerthi , Quinqueloculina eburnea , Q. bosciana , Haynesina germanica and Bolivina variabilis . The deleterious effects of pollution on the foraminiferal assemblage of biofacies III are clearly manifested by the highest incidences of test deformation.

Mercury-Pollution Induction of Intracellular Lipid Accumulation and Lysosomal Compartment Amplification in the Benthic Foraminifer Ammonia parkinsoniana

Heavy metals such as mercury (Hg) pose a significant health hazard through bioaccumulation and biomagnification. By penetrating cell membranes, heavy metal ions may lead to pathological conditions. Here we examined the responses of Ammonia parkinsoniana, a benthic foraminiferan, to different concentrations of Hg in the artificial sea water. Confocal images of untreated and treated specimens using fluorescent probes (Nile Red and Acridine Orange) provided an opportunity for visualizing the intracellular lipid accumulation and acidic compartment regulation. With increased Hg over time, we observed an increased number of lipid droplets, which may have acted as a detoxifying organelle where Hg is sequestered and biologically inactivated. Further, Hg seems to promote the proliferation of lysosomes both in terms of number and dimension that, at the highest level of Hg, resulted in cell death. We report, for the first time, the presence of Hg within the foraminiferal cell: at the basal part of pores, in the organic linings of the foramen/septa, and as cytoplasmic accumulations.

Impacts of several pollutants on the distribution of recent benthic foraminifera: the southern coast of Gulf of Gabes, Tunisia.

In addition to physicochemical methods, benthic foraminifera have become an essential tool for the assessment of polluted environments. The main objectives of the present work were to study the distribution of benthic foraminifera along the coastline of Skhira and Gabes (southern coast of Gulf of Gabes) and to predict the impact of pollution on these organisms. Thirty-one samples were studied and a polluted area was delimited by chemical analysis, where heavy metal, fluoride, phosphorus, nitrogen, and COT contents are very high. Thirty-four species of benthic foraminifera were identified and their response to pollution is very remarkable, in which their distribution shows barren area, corresponding to the highly polluted area. Away from the contaminated area, the density and the diversity of these organisms increase. Statistical analyses (principal component analysis (PCA)/FA and matrix correlation) show a possible control of these pollutants on biotic indices (with negative correlation), in addition to the presence of tolerant and sensitive species to pollution. A variety of test malformations were noticed especially in Ammonia beccarii, Peneroplis planatus, Sorites variabilis, and Adelosina pulchella. Unpolluted stations were dominated by species characteristic of shallow water environments with sandy sediment such Ammonia parkinsoniana, Triloculina trigonula, Quinqueloculina agglutinans, and P. planatus.

Spatial Distribution of Benthic Foraminifera in the Palar Estuary, Tamil Nadu

Abstract: Spatial variability of estuarine benthic foraminiferal assemblages in the surface (0-1cm) sediments has been determined for the Palar river estuary, Tamil Nadu. Twelve bottom water and sediment grab samples were collected at different water depths in the estuarine zone to determine the ecological relationship of benthic foraminiferal assemblages with physicochemical characteristics. The water analyses revealed that hypo saline, high dissolved oxygen and low pH conditions were prevailing at water-substrate interface at the time of sampling. The study indicated that salinity, pH and substrate have a patchy linear relationship with living and total faunal frequency but individual species Ammonia beccarii, A. tepida and A. parkinsoniana showed positive linear correlation with salinity and dissolved oxygen values. The restricted connectivity of the estuary with Bay of Bengal and frequent anthropogenic activity appeared to have an adverse effect on the faunal abundance, diversity and spatial distribution. The Q mode cluster analysis based on single linkage approach was performed to determine if any groups of samples or species correlated with ambient environmental factors. The study identified a total of 36 benthic foraminifer species belonging to 3 sub-orders. The faunal assemblages were dominated by two species Ammonia parkinsoniana and A.beccarii nearly at all the sampling stations.

Bathymetric zonation of modern shelf benthic foraminifera in the Levantine Basin, eastern Mediterranean Sea

Siliciclastic carbonate-poor sediments are common in southern and central parts of the inner Israeli shelf, part of the Nile littoral cell and in deeper water along the entire coast, while carbonate rich sediments occur in northern Israel and in submerged rocky environments. The distribution of benthic foraminifera, common components of these environments, was studied in surface sediment samples in order to identify their bathymetric zonation using multivariate statistical analyses. The dead foraminiferal assemblages exhibit a clear bathymetric zonation directly related to substrate type. A distinct faunal change has been found at approximately 40m water depth coinciding with the shift from the shallow-water sand belt, distributed parallel to the Israeli coast up to Haifa Bay, to a silty–clayey belt relatively rich with organic matter extending westward along the entire SE Mediterranean shelf. Ammonia parkinsoniana, Ammonia sp. 1, Buccella granulata, Nubeculina divaricata and Adelosina sp. 1 predominating the shallow-water depths are positively related to sand content and negatively related to water depth. Other species, such as Asterigerinata mamilla, Hanzawaia rhodiensis, Reussella spinulosa, Triloculina marioni and Valvulineria bradyana, occurring between 40 and 100m, exhibit a positive relationship with total organic carbon content and water depth. Beyond the Nile littoral cell and partly in its distal part Amphistegina lessonii, Peneroplis pertusus, Pseudoschlumbergerina ovata, Pseudoschlumbergerina sp. 1 and Quinqueloculina ungeriana dominate the rocky and coarse sand substrate, exhibiting a more positive relationship with higher carbonate content values. The distinct bathymetric zonation established in this study may prove to be useful in fossil records for accurate paleo-bathymetry reconstruction of Quaternary records in this dynamic system prone to frequent sea level fluctuations.

Effects of lead pollution on Ammonia parkinsoniana (foraminifera): ultrastructural and microanalytical approaches.

The responses of Ammonia parkinsoniana (Foraminifera) exposed to different concentrations of lead (Pb) were evaluated at the cytological level. Foraminifera-bearing sediments were placed in mesocosms that were housed in aquaria each with seawater of a different lead concentration. On the basis of transmission electron microscopy and environmental scanning electron microscopy coupled with energy dispersive spectrometer analyses, it was possible to recognize numerous morphological differences between untreated (i.e., control) and treated (i.e., lead enrichment) specimens. In particular, higher concentrations of this pollutant led to numerical increase of lipid droplets characterized by a more electron-dense core, proliferation of residual bodies, a thickening of the organic lining, mitochondrial degeneration, autophagosome proliferation and the development of inorganic aggregates. All these cytological modifications might be related to the pollutant-induced stress and some of them such as the thickening of organic lining might suggest a potential mechanism of protection adopted by foraminifera.

Compartimentos Ambientais do Estuário do Rio Arade, Sul de Portugal, com Base na Distribuição e Ecologia de Foraminíferos

In September 2010 five sediment samples were collected along the estuary of the Arade River aimed to identify environmental compartments based on the distribution of foraminifera species and their relationship with physic-chemical, sedimentological and geochemistry parameters. In the estuary were identified 39 foraminifera species, from wich 31 were calcareous species and 8 agglutinated species that which showed the great species richness values in Arade Estuary. The dominant species were Ammonia tepida and Haynesina germanica that were identified in all sample stations. The mouth of estuary showed the highest values of richness of specimens (31) and diversity (2.73) that demonstrated the strong marine influence in this region. Applying DAC multivariate analysis was possible to identify three areas in the estuary: Section A - region of greater marine influence that has a high concentration of inorganic carbon, sandy sediment and a large number of exotic species transported from adjacent platform (Cibicides bertheloti, Asterigerinata mammila, Bolivina ordinaria and Bolivina elongata); Sector B - middle region of the estuary with muddy sediment, high organic carbon and consists of species typical of estuaries. Sector C - more confined region of the estuary, with muddy sediment, higher concentration of organic carbon in relation to sector B, which is represented by species of agglutinated foraminifera and Ammonia parkinsoniana.

Benthic foraminifera for environmental monitoring: a case study in the central Adriatic continental shelf.

A study of benthic foraminifera was carried out in sediment samples collected from the central Adriatic coast of Italy, near the Ancona harbour and the Falconara Marittima oil refinery, in order to validate and support their use as bioindicators of ecosystem quality. On the basis of a principal component analysis (PCA), three biotopes (following the bathymetric gradient) have been documented, showing that the distribution pattern of benthic foraminifera is principally related to riverine inputs, organic matter contents at the seafloor, and sediment grain size. We observed higher abundances of opportunistic, low-oxygen tolerant taxa along the coastline, thus being representative of polluted environmental conditions. Near the Falconara Marittima oil refinery, the microfaunal assemblages is characterized by the absence of living specimens and by a low diversity associated with the dominance of opportunistic species. At this site, aberrant tests were also found. The data point out that Ammonia parkinsoniana and Quinqueloculina seem to be the most sensitive taxa and can be considered as good bioindicators of environmental stress in this area. This study confirms that faunal composition and morphology of benthic foraminifera respond to human-induced environmental perturbations, making their study potentially useful for biomonitoring in coastal-marine areas.

Benthic foraminifera assemblages as elemental pollution bioindicator in marine sediments around fish farm (Vrgada Island, Central Adriatic, Croatia)

Effects on sediments of fish farming activity near Vrgada Island was analysed through living and total foraminiferal assemblages and concentration of major, minor and trace elements from three sediment cores. Elemental concentrations of sediments are in accordance with carbonate characteristics of the surrounding area and show mostly natural element variations between sampling locations and throughout the cores, with no significant increases due to fish farming activity. Only phosphorus concentration shows elevate values below the fish cage, assigned to fish pellets. Foraminiferal communities are dominated by epifaunal and stress tolerant species, while diversity indices point to normal marine conditions. The type of substrate and phosphorus content in sediments principally influence foraminiferal community composition, while other elemental concentrations have no perceptible effect on the assemblages. Some foraminiferal species Ammoniatepida, Ammoniabeccarii, Elphidiumcrispum, Elphidiummacellum and genus Haynesina are confirmed to be tolerant to elevated nutrient (phosphorus) content, while Ammonia parkinsoniana shows sensitivity to pollution. Postmortem processes cause decrease of foraminiferal density and species richness with core depth. All results point to negligible influence of fish farming and relatively stable environmental conditions at all sampling locations.

Regional generalisations about the relationships between the environment and foraminifera along the SW Cape coast, South Africa

Factors influencing the composition of shallow water benthic foraminifera along the SW coast of South Africa at two locations (Table Bay, TB; St Helena Bay, SHB) ∼200km from each other were examined. Small taxa dominated in both locations; living assemblages from SHB (28 species, Ammonia parkinsoniana dominant) differed from TB (34 species, Elphidium articulatum dominant). Environmental parameters were similar in both areas. Patchiness in assemblage structure was pronounced, differences between pipeline and non-pipeline sites within locations were evident in environmental parameters. Diversity was significantly correlated with grain size, the nitrogen and heavy metal content (especially Cd). These data represent the first for extant benthic Foraminifera from the southern Benguela upwelling area and is the first attempt at using foraminifera as indicators of pollution in this region. The data stressed the need for more than one sampling location to better understand the factors influencing foraminiferal assemblages in any regional context.

Reconstrução paleoambiental da Laguna de Maricá, RJ, com base em foraminíferos bentônicos

Com o objetivo de avaliar a evolução costeira baseada na distribuição dos foraminíferos bentônicos e nos aspectos sedimentológicos, duas testemunhagens foram realizadas na Laguna de Maricá, Rio de Janeiro. Duas biofácies foram reconhecidas: (i) biofácies Ap-At (Ammonia parkinsoniana - A. tepida) correspondendo à metade inferior de ambos os testemunhos, caracterizada pela abundância de foraminíferos calcário-hialinos, entre os quais destacam-se Ammonia parkinsoniana e A. tepida, associada à intercalação de lama siltosa e lama arenosa com conchas desgastadas e quebradas, sugerindo eventos de ondas de tempestades; e (ii) biofácies Ac-As (Ammotium cassis - A. salsum) compreendendo à metade superior dos testemunhos, caracterizada por espécies aglutinantes, como Ammotium cassis, A. salsum, Trochammina inflata, Miliammina fusca e Ammobaculites spp., associados à lama siltosa e à ocorrência de alguns micromoluscos, indicando uma fase de baixa energia hidrodinâmica. Este registro da distribuição de foraminíferos calcários e aglutinantes relaciona-se principalmente com a dinâmica de abertura e fechamento da barreira arenosa da Laguna de Maricá.

Micropaleontological record of Holocene estuarine stages in the Bahía Blanca estuary, Argentina

Holocene paleoenvironmental changes have been interpreted on the basis of benthic foraminifera and calcareous nannofossils recovered in samples from Napostá Grande Stream, Bahía Blanca estuary, southern Buenos Aires Province. Samples are fine sands and clay sediments from a Holocene outcrop and were studied with quantitative techniques. The benthic foraminiferal assemblage is dominated by Ammonia parkinsoniana, Ammonia tepida, Bolivina pseudoplicata, Bolivina striatula, Bolivina sp., Buccella peruviana, and Elphidium spp. The calcareous nannofossil assemblage recovered is a typical cold-water association, dominated by Calcidiscus leptoporus, Coccolithus pelagicus, Emiliana huxleyi and Gephyrocapsa oceanica. A dendrogram classification by cluster analysis was made for each microfossil group. The results of these analyses were coincident, showing a liaison between changes in the assemblages of benthic foraminifera and calcareous nannofossils. Those results, jointly with the sedimentological information, lead to the identification of three different paleoenvironments along the Napostá N1 site. The lower part of the succession represents an estuarine environment with larger marine connection. The middle part represents a gradual passage to a more restricted estuarine environment, and the upper part represents the establishment of the modern continental fresh-water environment.

100 Years of benthic foraminiferal history on the inner Texas shelf inferred from fauna and stable isotopes: Preliminary results from two cores

Coastal regions, such as the Texas–Louisiana shelf, are subject to seasonal hypoxia that strongly depends on the magnitude of freshwater discharge from local and regional river systems. We have determined benthic foraminiferal fauna and isotopic compositions in two 210Pb dated box cores (BR4 and BR5) to examine the evidence for nearshore hypoxia and freshwater discharge on the Texas shelf during the last 100 years. The 210Pb chronologies of both cores reveal sedimentation rates of 0.2 and 0.1cmyr−1, translating to ∼60 and ∼90 year records. The fauna of both cores were almost exclusively composed of Ammonia parkinsoniana and Elphidium excavatum, indicating euryhaline ambient waters. The Ammonia–Elphidium (A–E) index, a qualitative measure of low oxygen conditions, shows an increase from values between 20 and 50 to near 100 in both cores, suggesting low oxygen conditions between 1960 and the core top. Between 1950 and 1960 (9–10cm), low A–E values in BR4 coincide with high δ18O and δ13C values greater than 0‰ and −1‰ respectively. This event corresponds to severe drought (the Texas Drought of Record) over the Brazos River drainage basin and considerably reduced river discharge from 1948 to 1957. High A–E values prior to this event imply low-oxygen conditions were prevalent prior to anthropogenic exacerbation of Louisiana shelf hypoxia and at least since the dredging of a new Brazos River delta in 1929. Elphidium excavatum δ13C values are very low (−4‰) and indicative of significant vital effect. The δ13C values of A. parkinsoniana average −3‰ and exhibit little variability, most likely reflecting pore waters influenced by aerobic and anaerobic respiration. The association of lowered Brazos River discharge with more oxygenated shelf bottom waters suggests Brazos River discharge and shelf hypoxia are linked, but the influence of Mississippi–Atchafalaya discharge can also contribute to shelf stratification.

Asociaciones De Foraminíferos Bentónicos En Secciones Holocenas Del Estuario De Bahía Blanca (Buenos Aires, Argentina): Caracterización Paleoambiental

ASSEMBLAGES OF BENTHIC FORAMINIFERA FROM HOLOCENE SECTIONS IN THE BAHÍA BLANCA ESTUARY (BUENOS AIRES, ARGENTINA). Benthic foraminifera associations are described from two Holocene sections, Canal Tres Brazas (38°54′S–62°14′W) and Canal del Medio (38°49′S–62°17′W), in the Bahía Blanca estuary, Buenos Aires Province. Micropaleontological analysis shows that both sections represent low intertidal to subtidal estuarine environments, affected by sea-level variations during the late Holocene. Among hyaline foraminifera, Buccella frigida (Cushman, 1922) dominates in both sections, mainly associated to Elphidium gunteri Cole (1931) and other species of Elphidium Montfort, 1808. Also present, but in low proportions are Ammonia tepida (Cushman, 1926) and Ammonia parkinsoniana (d'Orbigny, 1839) with bolivinids such as Bolivina striatula Cushman (1922) and Bolivina pseudoplicata Heron-Allen and Earland (1930). Among the most conspicuous miliolids are Miliolinella subrotunda (Montagu, 1803) and Quinqueloculina seminulum (Linné, 1767). The Canal del Medio section, dated at about cal. 3700 years BP represents a low intertidal to shallow subtidal estuarine environment, revealing energy oscillations in the depositional environment attributed to the cyclical action of tides. Features of these deposits indicate that the mean sea level at 3831–3610 years BP was located in a similar position to that of the present one. The Canal Tres Brazas section, the base of which was dated in cal. 1589–1371 years BP, shows a typical shallow intertidal fauna that gradually gives way to environments with greater continental influence, and without microfosiliferous content.

Benthic foraminiferal assemblages as pollution proxies in the northern coast of Gabes Gulf, Tunisia

A study of chemical and sedimentological parameters integrated with benthic foraminifera investigation was conducted along the northern coast of Gabes Gulf. Thirty-two samples were studied and a total of 68 benthic foraminiferal species were identified. Heavy metals enrichment factors and total hydrocarbon concentrations showed both metal and petrogenic pollution related mainly to phosphogypsum, sewage, and fishing activities. Statistical analysis (bivariate correlation and hierarchical cluster analysis) show a possible control of these pollutants on density, diversity, as well as the taxonomic composition of the benthic foraminiferal assemblages. The extent to which the population was found less dense and less diversified corresponded to the degree to which the sediment was contaminated. In these contaminated sites, an increase in relative abundance of opportunistic species such Ammonia tepida and Haynesina germanica was found. Far from pollution, foraminiferal assemblages are dominated by species characteristic of Mediterranean shallow water (Ammonia beccarii, Ammonia parkinsoniana, Elphidium crispum, Elphidium williamsoni, Elphidium advenum, Peneroplis planatus, Peneroplis pertesus).