259 research outputs found
Benthic foraminifera as a bioindicator of the environmental quality: a case study from the lagoon of Santa Gilla (Cagliari, Italy)
No full textBenthic foraminifera are increasingly used as environmental bio-indicators of pollution in coastal and marginal marine settings. Their community structure provides useful information on the general characteristics of the environment quality and some species are sensitive to specific environmental parameters (e.g., ALVE, 1991, 1995; YANKO et alii, 1994, 2002; COCCIONI, 2000; SAMIR, 2000; DEBENAY et alii, 2001, 2005; GESLIN et alii, 2002; COCCIONI et alii, 2003, 2005; ARMYNOT DU CHÂTELET et alii, 2004; COCCIONI & MARSILI, 2005; FRONTALINI & COCCIONI, 2008).
The lagoon of Santa Gilla, on an area of about 13 km2, is located on the southern coast of Sardinia (Italy) and communicates with the Mediterranean through a narrow channel. On the northern shore, the lagoon has two major freshwater inflows from the Rii Mannu and Cixerri rivers. On the west, the on-shore industrial area and the urban area of Cagliari discharged untreated wastewater from the mid-1960s to mid-1980s (DEGETTO et alii, 1997).
Sediment samples were collected from 18 stations during October 2006. Physicochemical data of water, geochemical, sedimentological, and benthic foraminiferal data (biocenosis and trace element contents in foraminiferal tests) have been analyzed to investigate the relationship between these sensitive microrganisms and trace element pollution.
The analysis of sediments indicated that the lagoon is deeply affected by trace element pollution (Cd, Ni, Pb, Zn and Hg). The biocenosis of the lagoon are largely dominated by Ammonia tepida, Haynesina germanica and Cribroelphidium oceanensis and, subordinately, by bolivinids.
Foraminiferal species and trace element concentrations were investigated both with bivariate (correlation matrix) and multivariate techniques of principal component analysis (PCA) and cluster analysis. Statistical analysis shows a possible control of these pollutants both on the taxonomic composition of the benthic foraminiferal assemblages and the development of test malformations which is used as additional tool for the pollution monitoring.
This study confirms and supports the suitability of studying benthic foraminifera as a technique for the in situ continuous bio-monitoring of trace element pollution of coastal marine sediments. This study was carried out within the framework of the ForamLag Project aimed at studying the response of benthic foraminifera to contaminants in the main Italian lagoons
Foraminiferal proxies for environmental monitoring in the polluted lagoon of Santa Gilla (Cagliari, Italy).
No full textThe results from scientific literature evidence that the benthic foraminifera are
excellent indicators to monitoring the marine-coastal environments (Armynot du Châtelet et
al., 2004; Coccioni, 2000; Debenay et al., 2000; Kravchuk, 2006; Murray, 2006; Samir & El-
Din, 2001; Scott et al., 2005). This study is based on an analysis of eighteen samples of
surface sediment collected in the lagoon of Santa Gilla in October 2006. The physicalchemical
characterization of waters, geochemical and sedimentological analysis have
integrated the analysis of benthic foraminifera. Statistical analysis revealed a possible control
of trace element on the benthic foraminiferal assemblage, faunal density, species diversity and
the development of specific morphological abnormalities
Preface: The stratigraphic record of Gubbio : integrated stratigraphy of the late Cretaceous-Paleogene Umbria-Marche pelagic basin
No full textForaminiferal proxies for environmental monitoring in the polluted lagoon of Santa Gilla (Cagliari, Italy).
No full textThe results from scientific literature evidence that the benthic foraminifera are
excellent indicators to monitoring the marine-coastal environments (Armynot du Châtelet et
al., 2004; Coccioni, 2000; Debenay et al., 2000; Kravchuk, 2006; Murray, 2006; Samir & El-
Din, 2001; Scott et al., 2005). This study is based on an analysis of eighteen samples of
surface sediment collected in the lagoon of Santa Gilla in October 2006. The physicalchemical
characterization of waters, geochemical and sedimentological analysis have
integrated the analysis of benthic foraminifera. Statistical analysis revealed a possible control
of trace element on the benthic foraminiferal assemblage, faunal density, species diversity and
the development of specific morphological abnormalities
Architectures in cretaceous planktonic foraminiferal test as a pproxy to detect major global perturbations
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How did the planktonic foraminifera respond to the extreme environmental stress induced by the OAE2 (Bonarelli Level) in the Bottaccione section (Gubbio, Italy)?
No full textRevets S. A. (Ed.), Forams 2002, International Symposium on Foraminifers, The University of Westrern Austarlia, Perth, 4-8 February 2002
Planktonic foraminifers across the Bonarelli Event (OAE2, latest Cenomanian): The Italian record
No full textA high-resolution, quantitative study of the planktonic foraminiferal assemblages across the Bonarelli Level (OAE2, latest
Cenomanian) of Italy from different areas and geological settings, has allowed the recognition of several events and biotic
changes, including acmes and crises of different genera. It provides evidence of a progressive and rapid change of
palaeoenvironmental conditions, reaching a climax coincident with the Bonarelli Event, and of the subsequent, gradual,
although not complete, resumption of previous conditions. The observed pattern is illustrated by marked changes in the
assemblages that indicate five discrete phases of environmental perturbation within the marine ecosystem. Though there are
several similarities, our analyses highlight that each section has its own peculiarities, clearly indicating more or less extreme
environmental conditions
Planktonic foraminifera and environmental changes across the Bonarelli Event (OAE2, latest Cenomanian) in its type area: a high-resolution study from the Tethyan reference Bottaccione section (Gubbio, central Italy).
No full textThe worldwide latest Cenomanian Oceanic Anoxic Event 2 (OAE2) was investigated for the planktonic foraminiferal assemblages in the type area of its sedimentare expression, the Corg–rich Bonarelli Level (Gubbio,
central Italy). The 313 kyr preceding the onset of OAE2 and the 153 kyr following the end of this event were analyzed in the deep-water setting of the Bottaccione section (Umbria-Marche Basin). For the first time, a highresolution approach and quantitative methods were applied.Several events and biotic changes, including the acme and crisis of different genera, were recognized. They provide evidence of a progressive and rapid deterioration of paleoenvironmental conditions, reaching a climax coincident with the Bonarelli Event, and of the subsequent, gradual (although not complete) recovery. Although no major mass extinction in planktonic foraminifera occurred across the Bonarelli Event, the extinction of the most specialized forms, i.e., the rotaliporids, and Globigerinelloides bentonensis, is recorded just bifore its onset. The observed pattern of marked changes in planktonic foraminiferal assemblages indicates five discrete phases of different degrees of environmental perturbation within the marine ecosystem. Phase I (313–55 kyr prior to the onset of OAE2) is characterized by a high planktonic foraminiferal abundance and diversity that imply a relatively stable environment, with different ecological niches occupied and stratified water column. On the other hand, relatively high percentages of hedbergellids and heterohelicids indicate a general meso-eutrophic environment and a well-developed oxygen minimum zone. Episodes of increased eutrophic conditions are indicated by pulses in abundance of radiolarians. A well-developed oxygen minimum zone may be related to a long-term change that precedes the onset of OAE2 (mid-Cenomanian Event). The most dramatic changes took place during Phase II and encompassed the last 55 kyr precedine deposition of the Bonarelli Level. The onset of a highstress environment is clearly shown by the shift to a distinctly unstable planktonic foraminiferal structure, characterized by low species diversity and marked foraminiferal changes and events. Some of these took place at the same time (the rotaliporid crisis, the heterohelicid decline, the Hedbergella-Schackoina shift, the onset of the ‘large form eclipse’ when larger 150 micron forms temporarily
disappeared) followed by other sequential events (onset of dwarfism, schackoinid acme, and hedbergellid acme). The 150 micron forms temporarily disappeared) followed by other sequential events (onset of dwarfism, schackoinid acme, and hedbergellid acme). The above-mentioned changes and events indicate for Phase II an increased surface productivity, enhanced oxygen minimum zone, and marked rapid changes of ecological parameters (e.g., temperature, salinity, trace metals). These marked foraminiferal changes culminate at the base of the Bonarelli Level with the temporary disappearance of all planktonic foraminifera. Phase III (100–900 kyr) coincides with the Bonarelli Level deposition and is characterized by highly eutrophic conditions, as indicated by radiolarian proliferation. Phase IV (35 kyr), similar to phase II except for the absence of rotaliporids, is characterized by the proliferation of the opportunistic hedbergellids and schackoinids, indicating that the environment remained ecologically unstable. The end of ‘large form eclipse’ marks the base of Phase V. During Phase V (118 kyr), planktonic
foraminiferal abundance and diversity return to values comparable to those of Phase I, showing the gradual recovery of the ecosystem. However, high numbers of hedbergellids and heterohelicids suggest that the environmental perturbation related to the Bonarelli Event did not end during this phase, but continued well beyond deposition of the organic-rich layers. Our analysis shows that, in deep-water settings, the severe paleoenvironmental perturbation induced by the Bonarelli Event led to assemblages dominated by the small-sized, opportunistic hedbergellids and schackoinids. At the same time, the small-sized and presumably low-oxygen-tolerant, opportunistic heterohelicids underwent a marked decline. This scenario may be related to the exceptionally high-nutrient and low oxygen content of the seawater, but also to variation of other ecological parameters. The perforate, elongated chambers and tubulospines of schackoinids may represent the best survivorship tool to have achieved better oxygen and nutrient uptake. We infer that schackoinids are useful indicatore for extremely stressed environments in low- to middlelatitude, open-marine, deep-water settings during the Late Cretaceous
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