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Highlights • Foraminifera responded faster to environmental perturbations than macroorganisms. • Population densities doubled and Asterigerinata mamilla bloomed under stronger flow. • Excess of threshold values and changes to new ecosystems induce acme occurrences. Abstract Benthic foraminifera are deemed sensitive indicators of environmental conditions. Triggers and magnitudes of faunal response to environmental changes are yet poorly constrained. Benthic foraminiferal faunas were monitored annually at Ria Formosa (Algarve, Portugal) coastal lagoon since 2013. Distinct environmental changes were recognised during the monitoring period. The relocation of a tidal inlet in winter 2015 effected faster flushing, higher tidal levels, and stronger currents in the Esteiro do Ancão tidal channel. The epibenthic foraminiferal species Asterigerinata mamilla increased in abundance and the population densities of the whole fauna were double as high as before inlet relocation. Enhanced sediment redeposition was recorded and extensive polychaete colonies successively replaced firmground patches with oysters. The standing stock of the foraminiferal fauna declined in the next year due to food impoverishment, while the high hydraulic energy levels and high percentages of Asterigerinata mamilla maintained. Benthic foraminifera responded much faster to environmental perturbations than macroorganisms identifying them as powerful proxies in environmental studies.

Highlights • Investigations of the benthic foraminiferal distribution in the Elbe Estuary. • Low diverse assemblages are dominated by Ammonia species. • Low salinities and high-frequency dredging confines foraminiferal proliferation. • Over 40 years, changes in hydrodynamic conditions induced assemblage modifications. Abstract For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to human interventions. In addition, Global Changes are modifying the estuarine physiography, leading to a re-structuration of marginal marine benthic communities. The aim of this study is to document, the modern assemblage composition and the species-environment relations of benthic foraminifera upstream the Elbe Estuary (southern North Sea) and to observe what has changed since the first survey in 1981. For this purpose, a surface sampling was carried out from 22 stations along the transitional area of the Elbe Estuary. Living (rose-Bengal stained) and dead foraminiferal assemblages were analysed as well as hydrological and sedimentological parameters (such as salinity, pH, grain-size, and organic matter). Living faunas are characterized by very low densities and largely dominated by Ammonia species. Dead assemblages are more diverse and dominated by Ammonia aomoriensis, Haynesina germanica, and Cribroelphidium selseyense. Salinity and grain-size seem to be the major factors influencing foraminiferal distributions in the transitional area. Under the ongoing climate changes, future strategies will be taken to foster the application of benthic foraminifera as biomonitoring tool in the Elbe Estuary, via this baseline investigation.

Sedimentological, geochemical and benthic foraminiferal proxies were used to interpret changes of depositional environments in a mud entrapment inside the Guadiana River paleo-valley, northern Gulf of Cadiz, to understand the temporal variability of fluvial flooding events and to detect patterns of latitudinal climatic variability in western Iberia. The period between ca. 5800 and ca. 1250 cal yr BP was characterized by slowly accumulating coarse-grained sediments, high content of biogenic sand components, and high abundances of shallow-water benthic foraminiferal species. After ca. 1250 cal yr BP, the sedimentary environment was dominated by fine-grained sediments, with high abundances of opportunistic benthic foraminiferal species and successful colonizers, and high values of geochemical ratios indicative of enhanced terrigenous supply. Sedimentation rates increased drastically over the last ca. 500 years. The genesis of these environments was mainly driven by the variable frequency of fluvial flooding events driven by the regional climate variability. Low terrigenous sediment input under dry conditions prevailed in the older sedimentary unit. Flood frequency and terrigenous sediment supply increased during the younger unit. The variability of the North Atlantic Oscillation at centennial scales highly influenced the sediment supply during the last ca. 500 years, with high terrigenous supply during negative NAO conditions. Our results corroborate an N-S gradient along the Atlantic Iberia during middle and late Holocene, with more humid conditions in the northwestern and drier conditions towards the southeast. The gradient weakened over the past ca. 500 years, with increased rainfalls and flood events during the Little Ice Age., This study was made possible by the CADISED (Cadiz Shelf Sediment Depocentres) survey (MARUM research cruise POS482, Germany), and was also supported by projects UID/0350/2020 CIMA of the Portuguese Science Foundation (FCT) and CGL2011-30302-C02-02 and CTM2017-88237-P of the Spanish Ministry of Economy and Competitiveness. Isabel Mendes also thanks to FCT for Research Assistant contract DL57/2016/CP1361/CT0009.

Same-area comparison between patterns of Recent (living) and Holocene benthic foraminiferal assemblage composition is essential to validate their utility as proxies for paleoenvironmental reconstructions. Such reconstructions have scarcely been attempted in shelf environments. In this study, we compared living (stained), dead and Holocene benthic foraminiferal assemblages from the Gulf of Cadiz continental shelf off the Guadiana River. On average, 99% of the living benthic foraminiferal species were preserved in the dead assemblage and 95% in the fossil record. Several common species were assessed as indicators for certain environmental factors, including river discharge, supply of terrestrial organic matter, heavy metal concentrations, oxygen levels, substrate properties, hydrodynamic energy levels, sea-level rise and human impact. The paleoenvironmental reconstruction depicted five stages of Holocene environmental evolution of the Guadiana shelf over the last 11,500 cal yr BP. The characteristics of the stages, and the transitions between them, were in particular driven by changes in sea-level, influx of terrestrial organic matter and limits of productivity.

This study investigates the land-ocean interactions along the northern margin of the Gulf of Cadiz in the vicinity of the Guadiana River. Benthic foraminifera and sedimentological characteristics were analysed in a sedimentary sequence spanning ca. 5000 years (core 8, 22 m water depth) retrieved from the inner shelf prodeltaic wedge. The analyses were integrated in a temporal framework based on accelerated mass spectrometry radiocarbon dating. Paleoenvironmental changes and sediment transfer mechanisms from the continent to the shelf were investigated and related to climatic oscillations and anthropogenic impact in the region. The results allowed the identification of two main periods of deposition. The first period, from ca. 5150 cal. BP (core base) to 1500-1200 cal. BP, is characterised by a mix of fine and coarse sediments, relatively constant percentages of terrigenous and bioclasts, and benthic foraminifera species characteristic of coastal environments. These features indicate an environment strongly influenced by discharge from the Guadiana River. The second period, from ca. 1500-1200 cal. BP to ca. 200 cal. BP (core top), is characterised by silt-clay fraction dominated sediments, an increase in terrigenous sediment towards the top, and benthic foraminifera species characteristic of environments with low levels of energy. An increase in the level of human occupation associated with changes in climate led to widespread erosion and soil loss to the continental shelf during this period, with possible silting up of the Guadiana eastern distributary, allowing the transport of high amounts of sediment to the shelf by the western distributary that led to the enhancement of fine sedimentation and the formation of the prodeltaic wedge in the area of the studied core. info:eu-repo/semantics/publishedVersion

20 pages, 8 figures, 1 table.-- Printed version published Mar 30, 2004., The response of coccolithophore assemblages to short-term millennial and centennial climatic changes over the last 50 kyr is studied in core M39029-7 from the Gulf of Cadiz (Atlantic Ocean) and core MD95-2043 from the Alboran Sea (Western Mediterranean Sea). The nannoplankton data are compared with oxygen isotopes, U37k′-SST and other biogeochemical and sedimentological proxies to obtain a new perspective of the paleoceanography and paleoecology of the area during these short-term climatic changes. Coccolithophores indicate that Heinrich events (HE) were characterised by the presence of cold, low salinity and turbid water masses on both sides of the Strait of Gibraltar. High abundances of the Lower Photic Zone (LPZ) species Florisphaera profunda in the Gulf of Cadiz synchronous with HE are interpreted as being an evidence of upper water-column stratification on the Atlantic side. These episodes coincided with input of terrigenous material, especially during H2. Surface waters during Dansgaard-Oeschger (DO) Stadials were also cold and turbid, while most of DO Interstadials were characterised by warm-water flora. The increase in small placoliths (small Gephyrocapsa and Emiliania huxleyi (4 μm), which is considered here as a cold-water indicator. The sharp decrease in large specimens of E. huxleyi related to the warming trend in the last deglaciation can be used as a biostratigraphic reference level that marks—at least approximately—the deglaciation and the beginning of the Holocene. Peaks of F. profunda are observed during Termination 1 (T1) in the Alboran Sea. They are isochronous with the “Organic-Rich Layer 1” recognised in the Western Mediterranean. In this interval, the water column of the region was stratified as a consequence of the global increase in the sea level following the deglaciation. Quantitative analyses of the coccolithophore assemblage allow us to interpret that coccolithophore production has been higher in the Alboran Sea than in the Gulf of Cadiz during the Holocene., This study was supported by an FPU grant from the Ministry of Education, Culture and Sport of Spain to E. Colmenero-Hidalgo and by Spanish project CLI 1998-1002-CO2-O2 and FEDER project 1FD97-1178. Sedimentological and stable-isotope work on core M39029-7 was funded by the Deutsche Forschungsgemeinschaft (Grants Scha355/15 and Za157/15).

Publisher Summary The chapter presents a study related to molecular chaperones and their interactions through analytical ultracentrifugation and other methodologies. After a brief introduction into basic principles of the technique, the chapter presents practical examples to illustrate the ability of the methodology to resolve controversial questions in the chaperone field and discusses some results in the context of other methodologies used to determine quaternary structure. In an analytical ultracentrifugation experiment an analysis is made of the distribution of molecules according to their masses within a field of gravitation. This analysis can also be done using a preparative centrifuge, where the concentration gradient is measured after the run and drop fractionation of the contents of the tubes; however, in this case only final concentration profiles are obtained from a single centrifugation run and sedimentation must occur in the presence of preformed density gradients (for example, of glycerol or sucrose). The chapter discusses that determination of protein quaternary structure should never be based exclusively on relative methods. Only a few methodologies, such as analytical ultracentrifugation techniques, unambiguously deliver molecular masses of homo- or hetero-complexes in solution without the need for arbitrary assumptions. The chapter demonstrates the practicality of investigating the comparably large chaperonin heterocomplexes under equilibrium. The chapter concludes by stating that the investigation of chaperonin-substrate interactions will be a productive field for future analytical ultracentrifugation experiments.

An undisturbed 16 m late Pliocene-Pleistocene sediment core spanning 2.6 Myr of deposition was recovered from the Manihiki Plateau by the German research vessel Sonne in 1990. This core 34KL complements the heavily disturbed late Pliocene-Pleistocene core sections of DSDP Site 317, and is well suited for stratigraphic correlation. The sediments consist of calcareous microfossils (93–97% CaCO3), minor portions of siliceous microfossils and detrital minerals. All important calcareous microfossil zones could be identified and correlated with the magnetostratigraphic and isotope stratigraphic events, stages and periods. Due to the high degree of silica dissolution, the late Quaternary radiolarian Buccinosphaera invaginata Zone is the only siliceous fossil zone which could be identified. An interval with Globigerinoides gomitulus/pink was found within the middle Pleistocene which is clearly distinguished from the Globigerinoides ruber/pink interval of the late Pleistocene. The magnetostratigraphic Gauss-Matuyama and Matuyama-Brunhes boundaries as well as the Olduvai and Jaramillo events were clearly identified. The δ180 curve displays the 100 kyr (Milankovitch) and the 41 kyr (Laplace) cyclicity periods. The beginning of the Laplace Period and the last occurrence of the calcareous nannofossil Discoaster brouweri, which marks the end of the Pliocene, fall within the base of the Olduvai Event. There is also a marked drop in sedimentation rates around this time, which seems to be a regional phenomenon. Prominent 3.5 kHz subbottom reflectors at 8 ms and 15 ms reflection time are related to lithologic changes near the Mid-Pleistocene Revolution (MPR) and the beginning of the Laplace Period or the Pleistocene, respectively. It is possible to trace these reflectors laterally to the eroded eastern edge of the Manihiki Plateau where they can be tied to older strata.

Sediments of 13 piston cores from opposite continental slopes of the South China Sea, off southern China and Sabah (northern Borneo), were analyzed by sedimentological methods and dated by oxygen isotope stratigraphy. Sediments mostly consist of hemipelagic clay with 20% carbonate off Sabah and 40% off China. We calculated terrigenous and carbonate accumulation rates for up to 11 time-slices from the Holocene to oxygen-isotope stage 6. Terrigenous accumulation rates generally increase with water depth and reach a maximum at the middle slope off Sabah and at the lower continental slope off China. During glacial and interglacial times this distribution pattern did not markedly change, despite an increase of accumulation rates for glacial periods by a factor of 2 to 5 compared to interglacial periods. Rates are negatively correlated with positions of sea level, which controls the partition of fluviatile terrigenous material for deposition on shelf, slope, and abyssal plain. Carbonate accumulation rates are higher off China by a factor of 2 compared to Sabah, probably indicating higher calcareous plankton productivity.