Assessing atmospheric and oceanic teleconnections between the eastern and western Mediterranean over the past 8000 years

Holocene climate records from the Mediterranean are marked by pervasive millennial to centennial-scale climate variability. Here, we investigate East-West Mediterranean atmospheric and oceanic teleconnections by computing phase-relationships between oxygen isotope (δ18O) records generated on Soreq (East) and Chorchia (West) spelaeothems, as well as between δ18O and carbon isotope (δ13C) records from planktonic and benthic foraminifera from core PS009PC (East, Levantin Basin), ODP Site 963D (Central, Sicily Strait), and core KESC9-14 (West, Ligurian Basin). These marine sites are all located at intermediate water depths (560–460 m depth). Hence, the benthic foraminiferal δ18O records reflect mainly the intermediate ocean temperature/δ18O of the water mass, and the benthic δ13C is a proxy for the intensity of water flowing at the studied depth called Levantine Intermediate Water (LIW). For both western and eastern cores, the planktonic stable isotopic records reflect the climate-induced activity of the nearby river system. We find broadly in-phase relationships between the spelaeothem δ18O records and between the planktonic δ18O and δ13C records at most multi-centennial and millennial periodicities. This is indicative of closely linked (hydro-) climatic conditions in Southern Europe, the Levant, and North Africa over the last 8000 years. Conversely, at intermediate water depths, we find a distinct out-of-phase relationship between the East/Central and West Mediterranean benthic δ18O and δ13C records at 1000–2000 years periodicities. We interpret this see-saw pattern as indicative of a persistent regional influence of LIW on oceanographic conditions in the intermediate depths of the eastern basin. Conversely, we suggest a strong influence of the modified Atlantic Ocean inflow (MAW) in the intermediate water formation in the Western Mediterranean (‘Winter Intermediate Water’; WIW). This WIW overprints, at least partially, the LIW signal that reaches the western Mediterranean causing the out-of-phase relationship between the east and the west oceanographic signals at intermediate depths

Перший Всеукраїнський лінгвістичний форум молодих учених (21–23 квітня 2010 року, м. Київ)

Всеукраїнський лінгвістичний форум молодих учених «Українська мова у ХХІ столітті: традиції і новаторство» відбувся в Києві 21–23 квітня 2010 року. Його організували Інститут української мови НАН України та Рада молодих учених ІУМ НАНУ

Benthic foraminifera as tracers of brine production in the Storfjorden "sea ice factory"

Abstract. The rapid response of benthic foraminifera to environmental factors (e.g. organic matter quality and quantity, salinity, pH) and their high fossilisation potential make them promising bio-indicators for the intensity and recurrence of brine formation in Arctic seas. Such an approach, however, requires a thorough knowledge of their modern ecology in such extreme settings. To this aim, seven stations along a north–south transect across the Storfjorden (Svalbard archipelago) have been sampled using an interface multicorer. This fjord is an area of intense sea ice formation characterised by the production of brine-enriched shelf waters (BSW) as a result of a recurrent latent-heat polynya. Living (rose bengal-stained) foraminiferal assemblages were analysed together with geochemical and sedimentological parameters in the top 5 cm of the sediment. Three major biozones were distinguished. (i) The "inner fjord" zone, dominated by typical glacier proximal calcareous species, which opportunistically respond to fresh organic matter inputs. (ii) The "deep basins and sill" zone, characterised by glacier distal agglutinated fauna; these are either dominant because of the mostly refractory nature of organic matter and/or the brine persistence that hampers the growth of calcareous species and/or causes their dissolution. (iii) The "outer fjord" zone, characterised by typical North Atlantic species due to the intrusion of the North Atlantic water in the Storfjordrenna. The stressful conditions present in the deep basins and sill (i.e. acidic waters and low food quality) result in a high agglutinated ∕ calcareous ratio (A∕C). This supports the potential use of the A∕C ratio as a proxy for brine persistence and overflow in Storfjorden

Benthic and Planktic Foraminifera as Indicators of Late Glacial to Holocene Paleoclimatic Changes in a Marginal Environment: An Example from the Southeastern Bay of Biscay

Benthic and planktic foraminiferal assemblages from two sediment cores (2000 m depth, 44°33′N-2°45′W) were analyzed to first compare modern and dead faunas and next to study changes in the hydrology of the southeastern Bay of Biscay (SE BoB) over the last 12.8 cal ka BP. Considering benthic ecosystem characteristics, the first part of the paleorecord (12.8–7.6 cal ka BP) is composed of laminated sediments that may have resulted from turbiditic overflow events, whereas occurrences of transported species (e.g. Nonionella sp., Cassidulina carinata) attest of continental influence at the core location. After 7.6 cal ka BP, the sediment becomes bioturbated concomitantly to the stabilization of the sea-level. The benthic foraminiferal fauna is largely dominated by Uvigerina peregrina suggesting a high seasonality with seasonal pulsed organic matter fluxes to the seafloor. On the other hand, the planktic foraminiferal composition indicates that surface water masses were under the influence of the polar front in the early record, which retreated at about 11.5 cal ka BP. The early Holocene is characterized by relatively warm and stratified water masses at 8.4–4.8 cal ka BP. The last 4.8 cal ka BP records a gradual sea surface water cooling trend and enhanced foraminiferal production from ~2.6 cal ka BP until present. The early (12.8–10.5 cal ka BP) and late (2.3–1.7 cal ka BP) Holocene are characterized by the presence of the planktic species Globigerinoides ruber probably caused by intrusions of the Iberian Poleward Current (IPC), and a negative state of the North Atlantic Oscillation (NAO)

Les foraminifères benthiques : bio-indicateurs l'eutrophisation naturelle et anthropique en milieu marin franc

The aim of this work is to evaluate the potential utilisation of benthic foraminifera as bioindicators of eutrophication phenomena in open marine environments. More precisely, we have compared different types of eutrophicated environments, in natural (sediments of the Rhône prodelta) and anthropogenic conditions (oil drill cuttings off Congo and Gabon; sewage sludge in the Firth of Clyde in Scotland). In this context, we studied the spatial distribution of benthic foraminifera, and compared their distributional patterns with the available physico-chemical parameters. Foraminifera are amongst the most abundant protists in benthic marine environments. Because of their high biodiversity, their short life cycles and the specific ecological requirements of the various species, foraminiferal faunas react quickly to the environmental disturbances. Our study reveals a typical faunal succession in response to an increasing gradient of organic enrichment. When approaching the source of organic enrichment, a diminution of the species characteristic of stable environments is observed; these species are replaced gradually by more opportunistic taxa in the highly enriched area. If the environmental degradation is persistent, only species very resistant to the environmental stress are present, generally with low densities. Thus, benthic foraminifera represent a very good tool to evaluate the impact of ecosystem eutrophication. These bio-markers can be used successfully in environmental monitoring and in survey networks of marine environments in order to evaluate the impact on the ecosystem of environmental disturbance.Ce travail de thèse a pour objectif d'évaluer la possibilité d'utilisation des foraminifères benthiques comme bio-indicateurs des phénomènes d'eutrophisation en milieu marin ouvert. Le but de notre étude est de comparer différents types d'environnements eutrophiés, sous des conditions naturelles (sédiments du prodelta du Rhône) et anthropiques (déblais de forages pétroliers au large du Congo et du Gabon ; boues d'épuration dans le Firth of Clyde en Écosse). Dans ce contexte, nous avons étudié la distribution spatiale des foraminifères benthiques et l'avons comparée aux paramètres physico-chimiques mesurés. Ces micro-organismes font partie des protistes les plus abondants dans les environnements marins benthiques. En raison de leur forte biodiversité, des courts cycles de vie et des exigences écologiques très variables des différentes espèces, les faunes de foraminifères réagissent rapidement aux perturbations environnementales. Notre étude révèle l'existence d'une succession faunistique typique en réponse à un gradient croissant d'enrichissement organique. Ainsi, en s'approchant de la zone la plus eutrophiée, une diminution des espèces caractéristiques des environnements stables est observée ; ces espèces sont remplacées progressivement par des espèces opportunistes en milieu fortement enrichi. Si la perturbation environnementale est persistante, seules des espèces très résistantes au stress environnementale sont présentes, généralement avec des faibles densités. Les foraminifères benthiques représentent donc un très bon outil d'évaluation de l'état de santé d'un environnement. Ces bio-marqueurs peuvent être employés avec succès dans des suivis d'impact environnemental et dans des réseaux de surveillance des milieux marins afin d'aider à évaluer les perturbations des écosystèmes

Les foraminifères benthiques (bio-indicateurs d'eutrophisation naturelle et anthropique en milieu marin franc)

Ce travail de thèse a pour objectif d'évaluer la possibilité d'utilisation des foraminifères benthiques comme bio-indicateurs des phénomènes d'eutrophisation en milieu marin ouvert. Le but de notre étude est de comparer différents types d'environnements eutrophiés, sous des conditions naturelles (sédiments du prodelta du Rhône) et anthropiques (déblais de forages pétroliers au large du Congo et du Gabon ; boues d'épuration dans le Firth of Clyde en Écosse). Dans ce contexte, nous avons étudié la distribution spatiale des foraminifères benthiques et l'avons comparée aux paramètres physico-chimiques mesurés. Ces micro-organismes font partie des protistes les plus abondants dans les environnements marins benthiques. En raison de leur forte biodiversité, des courts cycles de vie et des exigences écologiques très variables des différentes espèces, les faunes de foraminifères réagissent rapidement aux perturbations environnementales. Notre étude révèle l'existence d'une succession faunistique typique en réponse à un gradient croissant d'enrichissement organique. Ainsi, en s'approchant de la zone la plus eutrophiée, une diminution des espèces caractéristiques des environnements stables est observée ; ces espèces sont remplacées progressivement par des espèces opportunistes en milieu fortement enrichi. Si la perturbation environnementale est persistante, seules des espèces très résistantes au stress environnementale sont présentes, généralement avec des faibles densités. Les foraminifères benthiques représentent donc un très bon outil d'évaluation de l'état de santé d'un environnement. Ces bio-marqueurs peuvent être employés avec succès dans des suivis d'impact environnemental et dans des réseaux de surveillance des milieux marins afin d'aider à évaluer les perturbations des écosystèmes.The aim of this work is to evaluate the potential utilisation of benthic foraminifera as bioindicators of eutrophication phenomena in open marine environments. More precisely, we have compared different types of eutrophicated environments, in natural (sediments of the Rhône prodelta) and anthropogenic conditions (oil drill cuttings off Congo and Gabon; sewage sludge in the Firth of Clyde in Scotland). In this context, we studied the spatial distribution of benthic foraminifera, and compared their distributional patterns with the available physico-chemical parameters. Foraminifera are amongst the most abundant protists in benthic marine environments. Because of their high biodiversity, their short life cycles and the specific ecological requirements of the various species, foraminiferal faunas react quickly to the environmental disturbances. Our study reveals a typical faunal succession in response to an increasing gradient of organic enrichment. When approaching the source of organic enrichment, a diminution of the species characteristic of stable environments is observed; these species are replaced gradually by more opportunistic taxa in the highly enriched area. If the environmental degradation is persistent, only species very resistant to the environmental stress are present, generally with low densities. Thus, benthic foraminifera represent a very good tool to evaluate the impact of ecosystem eutrophication. These bio-markers can be used successfully in environmental monitoring and in survey networks of marine environments in order to evaluate the impact on the ecosystem of environmental disturbance.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Benthic foraminiferal census counts from sediment core MD03-2611 (South Australian margin, AUSCAN cruise)

The data presents benthic foraminiferal census counts from gravity core MD03-2611. The 11.97 m long core MD03-2611 was collected during the AUSCAN cruise in 2003 on-board the research vessel Marion Dufresne II (Hill and De Deckker, 2004). It was retrieved from a small plateau south of Kangaroo Island at 2420 m depth (36°43.80'S, 136°32.90'E) facing the mouth of the Murray River. The datasets cover the last 94 ka and have been used to understand how deep-sea benthic environments respond to changes occurring within surface waters and on land