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557 result(s) for "Langer, Martin"
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Spatial distribution of benthic foraminifera in the Lagos Lagoon (Nigeria): Tracing the impact of environmental perturbations
Lagos Lagoon is among Africa’s largest estuarine ecosystems, bordered by one of the fastest growing megacities in the world and the ultimate repository of contaminants carried in industrial, municipal and agricultural wastes. The high levels of pollutants have progressively deteriorated the water quality, adversely affected lagoon ecosystems, impacted the livelihood of the coastal population and pose serious risks to human health. Benthic foraminifera are excellent proxies and sensitive bioindicators of environmental disturbances but comprehensive studies on the structure, distribution, diversity and impact of pollution upon foraminiferal communities have not yet been conducted in the Lagos Lagoon. To demonstrate the potential of foraminifera as proxies of environmental perturbations, benthic foraminifera were investigated on a lagoon-wide basis. Lagos Lagoon comprises areas that range from low levels of direct impact to those of severely affected by various forms of anthropogenic disturbance. The goals of this study are to analyze patterns of distribution and species richness, to document foraminiferal community structures, and to identify taxa that track documented records of pollution in Lagos Lagoon sediments. Heat maps were generated from abundance records for selected species to illustrate environmental preferences and relative resistance levels to individual forms of anthropogenic disturbance. Sediments were analyzed for a range of physicochemical properties, via a multi-parameter sensor probe-device, including temperature, pH, depth and total dissolved solids (TDS). Quantitative analysis of 24 sediment samples yielded a total 3872 individuals of benthic foraminifera that belong to 42 species and 25 genera. They comprise 10 porcellaneous, 22 hyaline perforate and 10 agglutinated species. Ammobaculites exiguus , Ammotium salsum , Ammonia aoteana , Ammonia convexa and Trochammina sp. 1 have been found to be the most abundant species. For the first time, the complete present-day foraminifera fauna is illustrated here via scanning electron microscopy. The features recorded allow to assess the spatial effects of pollution upon foraminiferal assemblages on a lagoon-wide basis. The data generated may ultimately form the basis to assess the progressive deterioration of Lagos Lagoon ecosystems from cores by using benthic foraminifera as bioindicators of environmental perturbation.
Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia)
Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs is consistent with the disturbance-mosaic (microhabitat heterogeneity) hypothesis. Calculations of the FORAM Index (FI), a single metric index to assess reef vitality, indicate that all fore- and most back-reef environments support active carbonate accretion and provide habitat suitability for carbonate producers dependent on algal symbiosis. Lowest suitability values were recorded within the innermost bays, an area where natural and increasing anthropogenic influences continue to impact the reefs. The presence of habitat specific assemblages and numerical abundance values of individual taxa show that benthic foraminifera are excellent recorders of environmental perturbations and good indicators useful in modern and ancient ecological and environmental studies.
Patterns of species richness and the center of diversity in modern Indo-Pacific larger foraminifera
Symbiont-bearing Larger Benthic Foraminifera (LBF) are ubiquitous components of shallow tropical and subtropical environments and contribute substantially to carbonaceous reef and shelf sediments. Climate change is dramatically affecting carbonate producing organisms and threatens the diversity and structural integrity of coral reef ecosystems. Recent invertebrate and vertebrate surveys have identified the Coral Triangle as the planet’s richest center of marine life delineating the region as a top priority for conservation. We compiled and analyzed extensive occurrence records for 68 validly recognized species of LBF from the Indian and Pacific Ocean, established individual range maps and applied Minimum Convex Polygon (MCP) and Species Distribution Model (SDM) methodologies to create the first ocean-wide species richness maps. SDM output was further used for visualizing latitudinal and longitudinal diversity gradients. Our findings provide strong support for assigning the tropical Central Indo-Pacific as the world’s species-richest marine region with the Central Philippines emerging as the bullseye of LBF diversity. Sea surface temperature and nutrient content were identified as the most influential environmental constraints exerting control over the distribution of LBF. Our findings contribute to the completion of worldwide research on tropical marine biodiversity patterns and the identification of targeting centers for conservation efforts.
Atypical, high-diversity assemblages of foraminifera in a mangrove estuary in northern Brazil
Mangrove forests are extremely productive ecosystems, are sources and sinks of organic carbon, and provide essential services both to the marine environment and people. We have studied the composition and species richness of modern benthic foraminiferal assemblages from mangrove swamps along the Mamanguape River in Paraíba, northern Brazil. Sampling points for foraminifera were selected to acquire information on the composition of foraminiferal assemblages from dense mangrove stands collected along a river transect. Almost 100 species of benthic foraminifera were identified within the shallow mangrove habitats. The large number of identified mangrove taxa is the highest recorded so far for true mangrove habitats. The high species richness rivals shallow-water assemblages recorded from nearby offshore and reef environments and indicates that a particularly large number of species is capable of growing and flourishing under multiple stressor conditions. Numerical analysis of the faunal assemblages shows that specific taxa, which were previously known to be uncommon in mangrove environments, are abundant in the Mamanguape River estuary. The atypical foraminiferal fauna found in the Mamanguape River estuary resembles shallow-water offshore assemblages, is characterized by high percent abundances of perforate and miliolid taxa, and contains only very few of the otherwise typical and numerically abundant agglutinated mangrove taxa. The unusual structure of the assemblages recorded provides insight into what combination of environmental variables controls their composition and novel perspectives to reconstruct past mangrove environments. Distribution, diversity, and species-specific analysis will provide guidance on the use of Brazilian mangrove foraminifera as indicators for the strength of tidal activity, pollution, and anoxia in coastal waters and sea-level reconstructions.
Heading for New Shores: Projecting Marine Distribution Ranges of Selected Larger Foraminifera
The distribution of modern symbiont-bearing larger foraminifera is confined to tropical and subtropical shallow water marine habitats and a narrow range of environmental variables (e.g. temperature). Most of today's taxa are restricted to tropical and subtropical regions (between 30°N and 30°S) and their minimum temperature limits are governed by the 14 to 20°C isotherms. However, during times of extensive global warming (e.g., the Eocene and Miocene), larger foraminifera have been found as far north as 50°N (North America and Central Europe) as well as towards 47°S in New Zealand. During the last century, sea surface temperatures have been rising significantly. This trend is expected to continue and climate change scenarios for 2050 suggest a further increase by 1 to 3°C. We applied Species Distribution Models to assess potential distribution range changes of three taxa of larger foraminifera under current and future climate. The studied foraminifera include Archaias angulatus, Calcarina spp., and Amphistegina spp., and represent taxa with regional, superregional and global distribution patterns. Under present environmental conditions, Amphistegina spp. shows the largest potential distribution, apparently due to its temperature tolerance. Both Archaias angulatus and Calcarina spp. display potential distributions that cover currently uninhabited regions. Under climate conditions expected for the year 2050, all taxa should display latitudinal range expansions between 1 to 2.5 degrees both north- and southward. The modeled range projections suggest that some larger foraminifera may colonize biogeographic regions that so far seemed unsuitable. Archaias angulatus and Calcarina spp. also show an increase in habitat suitability within their native occurrence ranges, suggesting that their tolerance for maximum temperatures has yet not been fully exploited and that they benefit from ocean warming. Our findings suggest an increased role of larger foraminifera as carbonate producers and reef framework builders in future oceans.
Effects of sampling site, season, and substrate on foraminiferal assemblages grown from propagule banks from lagoon sediments of Corfu Island (Greece, Ionian Sea)
Foraminiferal propagule banks occur in fine sediment fractions that contain small individuals of benthic foraminifera. These sediments include locally sourced juveniles and propagules, as well as allochthonous propagules that have dispersed from surrounding areas. Such propagules can remain viable even under unfavorable local conditions. When exposed to more favorable conditions, they may grow to adult stages. Accordingly, during environmental changes, propagule banks have the potential to function as species pools and allow quick assemblage reactions. The propagule method was designed to study responses of foraminiferal assemblages by exposing propagule banks to controlled conditions in the laboratory, an approach that is applicable to a variety of ecological questions. Therefore it is important to understand the nature and dynamics of propagule banks, including local and seasonal influences. To obtain insights into the composition of local propagule banks, we studied experimentally grown assemblages from two shallow-water lagoons on Corfu Island in western Greece, and compared the results with in situ assemblages. We sampled in spring and autumn of 2017 and experimental treatments included the use of different substrates in our experiments to account for potential effects on assemblage compositions. Results revealed that sediments from each lagoon contained a distinct propagule bank. We found abundant allochthonous taxa among specimens grown in all experimental treatments, indicating dispersal of propagules, and possibly also juveniles, from adjacent regions into both lagoons. The time of sampling had a significant effect on experimental assemblages, indicating that the composition of propagule banks can vary throughout the year. However, no significant differences were found in assemblages grown in different substrata, suggesting a stronger influence of water variables (e.g., temperature or salinity) on assemblage compositions. Moreover, the experimental set-ups favored small, fast-growing, sediment-dwelling species tolerant of relatively high organic content. Our findings highlight the potential of propagule banks as species pools and will help to refine and improve future applications of the method.
Climate-Driven Range Extension of Amphistegina (Protista, Foraminiferida): Models of Current and Predicted Future Ranges
Species-range expansions are a predicted and realized consequence of global climate change. Climate warming and the poleward widening of the tropical belt have induced range shifts in a variety of marine and terrestrial species. Range expansions may have broad implications on native biota and ecosystem functioning as shifting species may perturb recipient communities. Larger symbiont-bearing foraminifera constitute ubiquitous and prominent components of shallow water ecosystems, and range shifts of these important protists are likely to trigger changes in ecosystem functioning. We have used historical and newly acquired occurrence records to compute current range shifts of Amphistegina spp., a larger symbiont-bearing foraminifera, along the eastern coastline of Africa and compare them to analogous range shifts currently observed in the Mediterranean Sea. The study provides new evidence that amphisteginid foraminifera are rapidly progressing southwestward, closely approaching Port Edward (South Africa) at 31°S. To project future species distributions, we applied a species distribution model (SDM) based on ecological niche constraints of current distribution ranges. Our model indicates that further warming is likely to cause a continued range extension, and predicts dispersal along nearly the entire southeastern coast of Africa. The average rates of amphisteginid range shift were computed between 8 and 2.7 km year(-1), and are projected to lead to a total southward range expansion of 267 km, or 2.4° latitude, in the year 2100. Our results corroborate findings from the fossil record that some larger symbiont-bearing foraminifera cope well with rising water temperatures and are beneficiaries of global climate change.
Spatial distribution of benthic foraminifera in the Lagos Lagoon
Lagos Lagoon is among Africa's largest estuarine ecosystems, bordered by one of the fastest growing megacities in the world and the ultimate repository of contaminants carried in industrial, municipal and agricultural wastes. The high levels of pollutants have progressively deteriorated the water quality, adversely affected lagoon ecosystems, impacted the livelihood of the coastal population and pose serious risks to human health. Benthic foraminifera are excellent proxies and sensitive bioindicators of environmental disturbances but comprehensive studies on the structure, distribution, diversity and impact of pollution upon foraminiferal communities have not yet been conducted in the Lagos Lagoon. To demonstrate the potential of foraminifera as proxies of environmental perturbations, benthic foraminifera were investigated on a lagoon-wide basis. Lagos Lagoon comprises areas that range from low levels of direct impact to those of severely affected by various forms of anthropogenic disturbance. The goals of this study are to analyze patterns of distribution and species richness, to document foraminiferal community structures, and to identify taxa that track documented records of pollution in Lagos Lagoon sediments. Heat maps were generated from abundance records for selected species to illustrate environmental preferences and relative resistance levels to individual forms of anthropogenic disturbance. Sediments were analyzed for a range of physicochemical properties, via a multi-parameter sensor probe-device, including temperature, pH, depth and total dissolved solids (TDS). Quantitative analysis of 24 sediment samples yielded a total 3872 individuals of benthic foraminifera that belong to 42 species and 25 genera. They comprise 10 porcellaneous, 22 hyaline perforate and 10 agglutinated species. Ammobaculites exiguus, Ammotium salsum, Ammonia aoteana, Ammonia convexa and Trochammina sp. 1 have been found to be the most abundant species. For the first time, the complete present-day foraminifera fauna is illustrated here via scanning electron microscopy. The features recorded allow to assess the spatial effects of pollution upon foraminiferal assemblages on a lagoon-wide basis. The data generated may ultimately form the basis to assess the progressive deterioration of Lagos Lagoon ecosystems from cores by using benthic foraminifera as bioindicators of environmental perturbation.
Healthcare Costs Associated with an Adequate Intake of Sugars, Salt and Saturated Fat in Germany: A Health Econometrical Analysis
Non-communicable diseases (NCDs) represent not only the major driver for quality-restricted and lost life years; NCDs and their related medical treatment costs also pose a substantial economic burden on healthcare and intra-generational tax distribution systems. The main objective of this study was therefore to quantify the economic burden of unbalanced nutrition in Germany--in particular the effects of an excessive consumption of fat, salt and sugar--and to examine different reduction scenarios on this basis. In this study, the avoidable direct cost savings in the German healthcare system attributable to an adequate intake of saturated fatty acids (SFA), salt and sugar (mono- & disaccharides, MDS) were calculated. To this end, disease-specific healthcare cost data from the official Federal Health Monitoring for the years 2002-2008 and disease-related risk factors, obtained by thoroughly searching the literature, were used. A total of 22 clinical endpoints with 48 risk-outcome pairs were considered. Direct healthcare costs attributable to an unbalanced intake of fat, salt and sugar are calculated to be 16.8 billion EUR (CI95%: 6.3-24.1 billion EUR) in the year 2008, which represents 7% (CI95% 2%-10%) of the total treatment costs in Germany (254 billion EUR). This is equal to 205 EUR per person annually. The excessive consumption of sugar poses the highest burden, at 8.6 billion EUR (CI95%: 3.0-12.1); salt ranks 2nd at 5.3 billion EUR (CI95%: 3.2-7.3) and saturated fat ranks 3rd at 2.9 billion EUR (CI95%: 32 million-4.7 billion). Predicted direct healthcare cost savings by means of a balanced intake of sugars, salt and saturated fat are substantial. However, as this study solely considered direct medical treatment costs regarding an adequate consumption of fat, salt and sugars, the actual societal and economic gains, resulting both from direct and indirect cost savings, may easily exceed 16.8 billion EUR.
Blood kinetics of Ebola virus in survivors and nonsurvivors
Infection with Ebola virus (EBOV) results in a life-threatening disease, with reported mortality rates between 50%-70%. The factors that determine patient survival are poorly understood; however, clinical observations indicate that EBOV viremia may be associated with fatal outcome. We conducted a study of the kinetics of Zaire EBOV viremia in patients with EBOV disease (EVD) who were managed at an Ebola Treatment Centre in Sierra Leone during the recent West African outbreak. Data from 84 EVD patients (38 survivors, 46 nonsurvivors) were analyzed, and EBOV viremia was quantified between 2 and 13 days after symptom onset. Time since symptom onset and clinical outcome were used as independent variables to compare EBOV viral kinetics in survivors and nonsurvivors. In all patients, EBOV viremia kinetics was a quadratic function of time; however, EBOV viremia was 0.94 logarithm (log) copies per ml (cp/ml) (P = 0.011) higher in nonsurvivors than in survivors from day 2 after the onset of symptoms. Survivors reached peak viremia levels at an earlier time after symptom onset than nonsurvivors (day 5 versus day 7) and had lower mean peak viremia levels compared with nonsurvivors (7.46 log cp/ml; 95% CI, 7.17-7.76 vs. 8.60 log cp/ml; 95% CI, 8.27-8.93). Before reaching peak values, EBOV viremia similarly increased both in survivors and nonsurvivors; however, the decay of viremia after the peak was much stronger in survivors than in nonsurvivors. Our results demonstrate that plasma concentrations of EBOV are markedly different between survivors and nonsurvivors at very early time points after symptom onset and may be predicative of outcome. Further studies focused on the early phase of the disease will be required to identify the causal and prognostic factors that determine patient outcome. Italian Ministry of Health; Italian Ministry of Foreign Affairs; EMERGENCY's private donations; and Royal Engineers for DFID-UK.