Benthic foraminifera and trace element distribution: A case-study from the heavily polluted lagoon of Venice (Italy)

Living benthic foraminiferal assemblages were studied in surface samples collected from the lagoon of Venice (Italy) in order to investigate the relationship between these sensitive microorganisms and trace element pollution. Geochemical analysis of sediments shows that the lagoon is affected by trace element pollution (Cd, Cu, Ni, Pb, Zn and Hg) with the highest concentrations in its inner part, which corresponds to the Porto Marghera industrial area. The biocenosis are largely dominated by Ammonia tepida, Haynesina germanica and Cribroelphidium oceanensis and, subordinately, by Aubignyna perlucida, Ammonia parkinsoniana and Bolivina striatula. Biotic and abiotic factors were statistically analyzed with multivariate technique of cluster analysis and principal component analysis. The statistical analysis reveals a strong relationship between trace elements (in particular Mn, Pb and Hg) and the occurrence of abnormalities in foraminiferal tests. Remarkably, greater proportions of abnormal specimens are usually found at stations located close to the heaviest polluted industrial zone of Porto Marghera. This paper shows that benthic foraminifera can be used as useful and relatively speedy and inexpensive bio-indicators in monitoring the health quality of the lagoon of Venice. It also provides a basis for future investigations aimed at unraveling the benthic foraminiferal response to human-induced pollution in marine and transitional marine environments.     

Testing benthic foraminiferal distributions as a contemporary quantitative approach to biomonitoring estuarine heavy metal pollution

Biomonitoring of estuarine pollution is the subject of active research, and benthic foraminifera are an attractive group to use for these purposes due to their ubiquitous presence in saline water and wide diversity. Here, we describe a case study of biomonitoring using benthic foraminifera in the French Mediterranean lagoon, Bages-Sigean lagoon. In this case, the major pollutants of interest are heavy metals in the sediment, particularly contaminated by Cu and Cd derived from industrial and agricultural sources. The foraminiferal assemblages of the Bages-Sigean lagoon are typical of normal paralic environments, but unusually almost completely lack agglutinated forms. The density of benthic foraminifera was shown to be more influenced by the sediment characteristics rather than heavy metal pollution. However, the relative abundance of Quinqueloculina bicostata was shown to increase in the most polluted areas and we propose that this taxon may be used as an indicator of heavy metal pollution.     

Benthic community response to habitat variation: A case of study from a natural protected area,the Celestun coastal lagoon

Little information currently exists on spatial and temporal benthic community variations in tropical coastal lagoons. Here, the benthic community response to habitat variation in the Celestun coastal lagoon, northwest Yucatan peninsula, was seasonally examined during the 1994–1995 climatic cycle into a grid of 12 sampling sites distributed along the salinity gradient of the lagoon. Habitat variation was assessed through physical factors associated both to the water column (e.g. salinity) and the bottom sediment (e.g. sand, silt and clay fractions). The benthic community response was assessed through species diversity measures and abundance. Under the influence of climatic seasonality, variations in habitat conditions followed by changes in the benthic community characteristics were expected. Results from two-way ANOVAs showed that for the period of study, Celestun lagoon was more heterogeneous along the spatial axis of variability than along the temporal one. Multiple regression analysis showed that salinity was spatially the main factor influencing the benthic community characteristics. Temporally, the sediment characteristics were observed to exert significant effects on the species diversity characteristics but not on abundance. Other variables assessed (dissolved oxygen, pH, temperature and water column transparency) exhibited no significant covariance with species diversity and abundance. Since generated from historical data, these results have the potential to be useful as a benchmark to the establishment of monitoring programs in the light of the increasing anthropogenic pressure on the natural resources of the lagoon and surrounding coastal area.     

Impact evaluation of the industrial activities in the Bay of Bakar (Adriatic Sea,Croatia): Recent benthic foraminifera and heavy metals

The Bay of Bakar is one of the most heavily polluted bays at the Eastern Adriatic. Three major industrial companies potentially endanger the bay. The concentration of major, minor and trace elements in surface sediments from thirteen stations was discussed in relation to the sediment type and foraminiferal assemblages. The distribution of major elements in the bay is influenced by geological nature of surroundings. Heavy metal distribution depends on pollution sources and on amount of mud fraction: fine-grained sediments are enriched by them in comparison with coarse-grained ones. Different sediment quality criteria complicate the pollution assessment in the bay. Heavy metal concentrations generally fall into allowed depositional values for marine environments; only area in front of the coke plant and the City of Bakar harbor is heavily polluted. Stress-tolerant foraminiferal species dominate at stations with higher concentrations of heavy metals and coarse-grained sediments consist of larger number of epifaunal taxa.     

Benthic foraminifera distribution in a tourist lagoon in Rio de Janeiro, Brazil: a response to anthropogenic impacts

Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentrations could supply important data about the conditions of the lagoon. The benthic foraminiferal assemblage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida - Elphidiumexcavatum foraminiferal assemblage is characterized by dwarf, corroded and weak organisms. Agglutinated species were found only near the entrance. Low abundance values and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage.     

Spatial distribution of trace elements associated with organic carbon along the Beiyun River basin,Beijing,China

Pollution resulting from terrestrial and aquatic trace elements has become a severe problem across the world. Organic carbon(OC) content has a high affinity for metallic contaminants and it acts as a significant sink for trace elements. The decomposition of OC content directly influences the bioavailability of trace elements. The decomposition of OC content and OC distribution vary spatially, these processes affect the release of trace elements and need further research. In the current study, se...     

Distribution and ecological relevance of fine sediments in organic-enriched lagoons: the case study of the Cabras lagoon (Sardinia, Italy)

In organic-enriched sedimentary systems, like many Mediterranean coastal lagoons, a detailed analysis of sediment grain size composition and partitioning within the muds is crucial to investigate sedimentological trends related to both hydrodynamic energy and basin morphology. In these systems, sediment dynamics are particularly important because the partitioning and transport of fine sediments can strongly influence the redistribution and accumulation of large amounts of organic matter, and consequently the distribution of benthic assemblages and the trophic status and functioning of a lagoon. Nevertheless, studies on benthic-sediment relationships have been based mainly on a rather coarse analysis of sediment grain size features. In muddy systems, however, this approach may impede a proper evaluation of the relationships and effects of the distribution of fine sediment and organic matter on the biotic benthic components. Here we show that the distribution of sedimentary organic matter (OM) and total organic carbon (TOC) in the Cabras lagoon (Sardinia, Italy) can be explained (i.e., predicted) as a function of a nonlinear increase in the amount of the cohesive fraction of sediments (< or = 8 microm grain size particles) and that this fraction strongly influences the structure, composition and distribution of macrobenthic assemblages. Even in such a homogeneously muddy system, characterized by "naturally" occurring impoverished communities, impaired benthic assemblages were found at < or = 8 microm, OM, TOC contents of about 77%, 11% and 3.5%, respectively. A review of studies conducted in Mediterranean coastal lagoons highlighted a lack of direct integrated analysis of sediment features and the biotic components. We suggest that, especially in organic-enriched coastal lagoons, monitoring programs should primarily investigate and consider the cohesive fraction of sediments in order to allow a better assessment of benthic-sediment relationships and ecological quality of the system.     

Bed diversity in the shallow water environment of Pappas lagoon in Greece

<正>Acoustic classification systems and the Sediment Trend Analysis method were used to identify and map the bed diversity in a very shallow(3.0m),coastal lagoon,Pappas lagoon,Western Greece. Analogue acoustic data,collected by means of a 100 kHz side scan sonar system,were digitized and classified into six acoustic classes using recently developed acoustic classification systems (SonarClass,TargAn).By comparing the acoustic classes to ground truth data consisting of sediment grain size and visual inspection of the lagoon-bed,it is demonstrated that the six acoustic classes correlate well with the predominant surface sediment types and vegetation.Thus the spatial distribution of the classes can be considered to represent the spatial pattern of the sedimentary assemblages of the lagoon.The grain size trend analysis identified three dominant sediment pathways and directional trends which could be related to the predominant wind direction,the sediment influx through the inlets and the sediment supply from a small stream in the southern part of the lagoon.The integration of acoustic and sedimentological data together with advanced data processing systems leads to a better understanding of the sedimentary,morphological and biological processes in a shallow lagoon in different spatial and temporal scales and will therefore be beneficial to both sedimentological and biotic-diversity studies.     

In situ experimental study of the evolution and recolonization of polluted sediments

When perturbing conditions influencing a benthic ecosystem improve, an extremely polluted sediment may very rapidly be colonized by a structured assemblage. This study was made after the implantation of modules containing chemically very contaminated sediment from a polluted biotope, in a lesser contaminated site. The colonization and dynamic processes of the studied mollusc populations do not depend on the concentrations of the solid phase pollutants but are related to the release of these pollutants in the interstitial water of sediments, which in turn is induced by ambiant condition variations and particularly by salinity.     

Trace element contamination in the estuarine sediments along Tuticorin coast – Gulf of Mannar,southeast coast of India

Sediment samples were collected from Kallar, Korampallam creek and Punnakayal estuaries of Tuticorin coast for assessing the level of contamination by trace elements in these estuarine sediments. The trace element concentration, calcium carbonate, organic carbon and mercury level were analyzed by Inductively Coupled Plasma Atomic Emission Spectrophotometer, Titrimetric method and SnCl₂ reduction method. The results reveals that the enrichment factor, metal pollution index and geo-accumulation index of these estuarine sediments were predominantly polluted by Cd, As, Zn, Hg and Pb. The factor analysis revealed the source of trace element accumulation in the estuarine sediments particularly Mn and Fe are from riverine inputs and As and Hg from untreated industrial effluents. Among the selected estuaries, Korampallam creek was found to be highly contaminated by trace elements due to the discharge of effluents from thermal power plant, Tuticorin alkali chemicals, copper smelting, Petrochemical industries and shipping activities.     

Linking the toxic metals to benthic community alteration: A case study of ecological status in the Bohai Bay

Ecological effects and quality status of sediments in the Bohai Bay (North China) were studied by incorporating the traditional chemical analysis and benthic community structure. In the present study, paired sediments from 20 stations were sampled for chemical analysis and benthic assemblages. The overall results demonstrated that sediment impairment mainly appeared in the southern part of the Bay. The results obtained from the principal component analysis regarding benthic data and potential explanatory factors indicated that As, Hg and petroleum hydrocarbons (PHs) were responsible for the distribution of macrofaunal assemblages. Canonical correspondence analysis further showed As was significantly correlated to the benthic alteration, which provided evidence of ecological relevance to chemical substances of concern. Overall, this study revealed the metal contamination in the Bohai Bay was not as severe as previously regarded. Yet, further investigation is still needed considering the complexity of sediment matrices.     

Erratum: Trace Elements in Sediments and Mussels – Spatial Distribution,Chemical Partitioning,and Risk Assessment

Sediment samples were collected from 30 different locations in Abu Qir Bay (Mediterranean Sea), East Alexandria, Egypt and analyzed for trace elements. The highest concentrations of most of the elements were observed in the nearshore stations in the vicinity of the major anthropogenic activities as industrial settlements, wastewater discharges, and agricultural drainage. In addition, mussel samples of Mactra corallina and Tapes decussata were collected corresponding to the sediment samples. Concentrations of As, Cd, Cr, Mn, and Zn in the mussel tissues were higher than concentrations in sediments, thus indicating their relatively high bioavailability. Sequential extraction procedure was performed on selected sediment samples. Significant correlations were observed between the concentrations of Cu, Mn, Pb, and Zn in the exchangeable fraction of the sediments and the corresponding tissues of M. corallina. The output of the risk assessment applied on the sediments revealed that adverse ecological effects to benthic species could occur and that a higher level of risk is expected from the exposure to Cd, Cr, Hg, and Zn. No adverse carcinogenic or non‐carcinogenic human health effects are expected from the consumption of the two mussel species from Abu Qir Bay.     

Characteristic analysis of phospholipid fatty acids(PLFAs) in typical nutrient polluted lake sediment in Wuhan

The process of urbanization aggravates the endogenous pollution of urban lake sediment,and polluted sediment may seriously affect the quality of the water in lakes.At present,it is difficult to distinguish the difference between sediment that is heavily polluted by nitrogen(N)and phosphorus(P)when using an analysis based on a physicochemical index classification.The current study applied phospholipid fatty acid(PLFA)technology to further analyze the sediment characteristics from the perspective of microbiology.Surface sediment from five urban lakes that are heavily polluted with N and P in Wuhan were sampled.Statistical approaches were used to analyze the microbial community structure in the sampled sediment,and to determine the correlations between the microorganisms and physicochemical indices.The most severely polluted lake sediment had similar PLFA structures,the highest saturated fatty-acid content,and bacteria as the dominant microorganism.However,there were differences between the microbial biomass of the various sediment samples,which may have been related to the degree of N and P pollution.Analysis of the microbial diversity in the sediment samples indicated that the bacteria were experiencing starvation and nutrient pressure,which may have been due to the dissolved oxygen concentration of the heavily polluted lake sediment.A correlation analysis showed that the endogenous N and P had different effects on the microbes of the polluted sediment.A redundancy analysis(RDA)demonstrated that the N/P ratio had the greatest influence on the PLFA species,accounting for 83%of the cumulative interpretation.To effectively promote the role of sediment microorganisms on circulating elements,it is necessary to regulate the N/P ratio of the sediment to some extent.When the N/P ratio in sediment exceeds 6,N pollution should be prioritized.     

Spatial and seasonal variability of sediment oxygen consumption and nutrient fluxes at the sediment water interface in a sub-tropical lagoon (New Caledonia)

In order to quantify the spatial and seasonal variations of sediment oxygen consumption and nutrient fluxes, we performed a spatial survey in the south west lagoon of New Caledonia during the two major seasons (dry and wet) based on a network of 11 sampling stations. Stations were selected along two barrier reef to land transects representing most types of sediments encountered in the lagoon. Fluxes were measured using ex-situ sediment incubations and compared to sediment characteristics. Sediment oxygen consumption (SOC) varied between 500 and 2000 μmol m⁻² h⁻¹, depending on season and stations. Nutrient effluxes from sediment were highly variable with highest fluxes measured in muddy sediments near the coast. Inter-sample variability was as high as seasonal differences so that no seasonally driven temperature effect could be observed on benthic nutrient fluxes in our temperature range. Nutrient fluxes, generally directed from the sediment to the water column, varied between −5.0 and 70.0 μmol m⁻² h⁻¹ for ammonia and between −2.5 and +12.5 μmol m⁻² h⁻¹ for PO₄ and NO₂₊₃. SOC and nutrient fluxes were compared to pelagic primary production rates in order to highlight the tight coupling existing between the benthic and pelagic compartments in this shallow tropical lagoon. Under specific occasions of low pelagic productivity, oxygen sediment consumption and related carbon and nutrient fluxes could balance nearly all net primary production in the lagoon. These biogeochemical estimates point to the functional importance of sediment biogeochemistry in the lagoon of New Caledonia.     

Trace Elements in Sediments and Mussels – Spatial Distribution,Chemical Partitioning,and Risk Assessment

Sediment samples were collected from 30 different locations in Abu Qir Bay (Mediterranean Sea), East Alexandria, Egypt and analyzed for trace elements. The highest concentrations of most of the elements were observed in the nearshore stations in the vicinity of the major anthropogenic activities as industrial settlements, wastewater discharges, and agricultural drainage. In addition, mussel samples of Mactra corallina and Tapes decussata were collected corresponding to the sediment samples. Concentrations of As, Cd, Cr, Mn, and Zn in the mussel tissues were higher than concentrations in sediments, thus indicating their relatively high bioavailability. Sequential extraction procedure was performed on selected sediment samples. Significant correlations were observed between the concentrations of Cu, Mn, Pb, and Zn in the exchangeable fraction of the sediments and the corresponding tissues of M. corallina. The output of the risk assessment applied on the sediments revealed that adverse ecological effects to benthic species could occur and that a higher level of risk is expected from the exposure to Cd, Cr, Hg, and Zn. No adverse carcinogenic or non‐carcinogenic human health effects are expected from the consumption of the two mussel species from Abu Qir Bay.     

Relative importance of multiple environmental variables in structuring benthic macroinfaunal assemblages in chronically metal-polluted salt marshes

In this study, we assessed importance of sediment-associated trace metals in structuring benthic macroinfaunal assemblages along multiple environmental gradients in chronically polluted salt marshes of the Arthur Kill - AK (New York, USA). More than 90% of benthic macroinfaunal communities at the northern AK sites consisted of a considerably large number of only a few polychaete and oligochaete species. Approximately 70% of among-site variances in abundance and biomass of benthic macroinfaunal communities was strongly associated with a few environmental variables; only sediment-associated mercury consistently contributed to a significant proportion of the explained variances in species composition along natural environmental gradients (e.g., salinity). Although sediment-associated copper, lead, and zinc were substantially elevated at some of the AK sites, their ecological impacts on benthic macroinfaunal communities appeared to be negligible. These findings suggest that cumulative metal-specific impacts may have played an important role in structuring benthic macroinfaunal communities in chronically polluted AK ecosystems.     

Trace elements in alluvia of the upper Vistula as indicators of palaeohydrology

In the Vistula valley near Góra, at the northern foreland of the Carpathians Mountains, there are young alluvia deposited in the historical period. These alluvia are difficult to date precisely because of the lack of organic interbedded material. In the Vistula drainage basin upstream of Góra since the second half of 18th century small centres of metal, textile, motor, and petrochemical industries have been developed. Concentrations of trace elements such as: Cr, Mn, Co, Ni, Cu, Zn, Cd, Pb, and of some macroelements were used as indicators of the age of different alluvial fills. The main part of the Vistula valley floor was built up by sediment accumulation before the development of industry but after the medieval phase of rural colonization of the Carpathians. Deposits filling the abandoned channels dissecting the valley floor have an increased content of some trace elements and deposits date from the second half of the 18th century, when the first foundries and blacksmith's shops were developed. A drastic increase of concentration of the most abundant trace elements in the youngest alluvial fill indicates that the fill dates from the last decade of rapid industrial development.     

The use of the marine biotic index AMBI in the assessment of the ecological status of the Obidos lagoon (Portugal)

This study reports the longitudinal distribution of sediment properties, including inorganic and organic contaminants, and the structure of the benthic community in Obidos lagoon, a coastal system permanently connected to the sea and with negligible freshwater sources. Sediments from the upper to central lagoon consist of fine particles (91%) and from the lower lagoon of sands (94%). Chemical composition is strongly correlated to the percentage of fine particles. Contamination is relatively low in those sediments suggesting the effect of diffuse sources. The increase in organic matter content from down- to upstream areas was associated with the dominance of opportunistic species, while sensitive and indifferent species to organic enrichment were mainly associated to the clean sandy downstream area. The marine biotic index (AMBI) was suitable for the discrimination of the biological and environmental gradients in the Obidos lagoon and was highly related with the gradient of organic matter content in this system.