RECENT PUBLICATIONS ON FORAMINIFERA 2011 (5)
FORAMINIFERA FROM THE UPPER CRETACEOUS OF NORTHERN JAMES ROSS ISLAND (ANTARCTICA)
During geological mapping of the northern James Ross Island a number of samples from Upper Cretaceous lithologies were gathered to test the presence of foraminifers as a possible tool for stratigraphic evaluation of Upper Cretaceous strata. Limited number of samples did not provide foraminiferal content large enough to give relevant information for biostratigraphic conclusions. Samples from older sediments of Whisky Bay and Kotick Point formations (Albian – Turonian) were either not fossiliferous or contained scarce specimens of agglutinated foraminifers. Foraminiferal assemblages from younger sediments of Hidden Lake and Santa Marta formations (Coniacian – Campanian) contained species with both agglutinated and calcareous types of tests. Many of studied marine sediments were barren of foraminifers, probably due to late diagenetic secondary decalcification. Taxonomy of low-diversified assemblages was carried out and a biostratigraphical and palaeobiogeographical significance discussed. (ABSTRACT)
Hradecká, L., Vodrážka, R., Nývlt, D., 2011. Foraminifera from the Upper Cretaceous of northern James Ross Island (Antarctica): a preliminary report. Czech Polar Reports 1 (2), 88-95.
TAXONOMIC REVISION AND EVOLUTIONARY CLASSIFICATION OF PRAEGLOBOTRUNCANIDS
The praeglobotruncanid test appearance was iteratively developed in three genera/directional lineages during the late Albian-Santonian. A new genus/directional lineage, Bermudeziana, and a new species, Fingeria praeglobotruncaniformis are described. A new system of species types is developed for the evolutionary classification, as a tool to describe the morphological changes within a lineage and compare the developments in lineages in which certain features were achieved independently (ABSTRACT)
Georgescu, M.D., 2011. Iterative evolution, taxonomic revision and evolutionary classification of the praeglobotruncanid planktic foraminifera, Cretaceous (late Albian-Santonian). Revista Española de Micropaleontología 43 (3), 173-207.
WALL ULTRASTRUCTURE AND TAXONOMIC POSITION OF THE GENUS Strictocostella
The details of the shell wall ultrastructure of Strictocostella matanzana (Palmer and Bermudez) 1936 and Strictocostella matanzana (Palmer and Bermudez) 1936 perytae subsp. nov. are investigated for the first time. This study shows that the calcareous shell wall of these two subspecies is monolamellar, consisting of one layer of crystals aligned in a radial direction. This fact necessitates changing the taxonomic position of the genus from the class Rotaliata which is characterized by a bilamellar shell wall to the class Nodosariata whose representatives have a monolamellar shell wall. Some other unique details of the shell and wall structure of the two subspecies studied are also described. The suborder Stilostomellina Saidova 1981 is reinstated and its rank is elevated to that of order. (ABSTRACT)
Mikhalevich, A.-V., 2011. Test wall ultrastructure and taxonomic position of the foraminiferal genus Strictocostella Patterson 1987. Micropaleontology 57 (6), 543--555.
Sanctus sinaicus, A NEW AMPHISTEGINID FROM THE UPPER EOCENE OF EGYPT
Sanctus sinaicus nov. gen et sp. is described from material collected in the uppermost part of the Khaboba Formation and throughout the Tanka and Tayiba formations of Wadi Thal and Wadi Matulla in West–Central Sinai. We assign this new genus and species to the Late Eocene according to associated planktonic foraminiferal assemblages. Its test is symmetrical in axial section with the division of chambers in the same section similar to that of amphisteginids in their early ontogenetic stage and lacks a canal system. In comparing Sanctus sinaicus with related amphistegenid species, such as Penoperculoides cubaensis Cole and Gravell 1952 from the Caribbean; Penoperculoides rozlozsniki (Méhes) ( ex: Nummulites rozlozsniki Méhes) from Hungary; and “Non Nummulites rozlozsniki” described by Sander 1962, from the Dammam Formation of Saudi Arabia, we find that Sanctus sinaicus is similar to P. cubaensis in the type of coiling and the character of the umbo, which lacks alar prolongations, a canal system and transverse trabeculae, and differs from species of Nummulites in the central subdivision of chambers. (ABSTRACT)
Boukhary, M., Abf-Elshafi, E., Mattar, Y., 2011. Sanctus sinaicus n. gen., n. sp. (Foraminiferida, Amphisteginidae) from Late Eocene of Sinai, Egypt. Micropaleontology 57 (6), 537--542.
CAMPANIAN AGGLUTINATED FORAMINIFERA FROM THE LOMONOSOV RIDGE
We document the occurrence of agglutinated foraminifera in Upper Cretaceous (Campanian) sediments recovered during the Arctic Coring Expedition (ACEX), IODP Expedition 302. Foraminiferal assemblages consist entirely of agglutinated taxa with 29 taxa including three new species (Labrospira macilenta, Recurvoidella arctica, and Recurvoides trochoidalis). The agglutinated assemblage from the Lomonosov Ridge represents a shallow, probably restricted, brackish environment, and displays some taxonomic affinity to Late Cretaceous assemblages described from the Beaufort-Mackenzie Basin. There are no species in common with coeval assemblages described from the southwestern Barents Sea or Western Siberia, and also only several cosmopolitan species in common between the later two regions. Therefore we suggest that the Arctic Ocean was probably isolated from the North Atlantic faunal province during the Late Cretaceous, with very limited or no marine connections between the Arctic, North Atlantic and Western Siberia over the Barents Shelf. (ABSTRACT)
Setoyama, E., Kaminski, M.A., Tyszka, J., 2011. Campanian agglutinated foraminifera from the Lomonosov Ridge, IODP Expedition 302, ACEX, in the paleogeographic context of the Arctic Ocean. Micropaleontology 57 (6), 507--530.
EARLY FORAMINIFERA IN POST-SATURTIAN (716–635 Ma)?
Foraminifera are an ecologically important group of modern heterotrophic amoeboid eukaryotes whose naked and testate ancestors are thought to have evolved ∼1 Ga ago. However, the single-chambered agglutinated tests of these protists appear in the fossil record only after ca. 580 Ma, coinciding with the appearance of macroscopic and mineralized animals. Here we report the discovery of small, slender tubular microfossils in the Sturtian (ca. 716–635 Ma) cap carbonate of the Rasthof Formation in Namibia. The tubes are 200–1300 μm long and 20–70 μm wide, and preserve apertures and variably wide lumens, folds, constrictions, and ridges. Their sometimes flexible walls are composed of carbonaceous material and detrital minerals. This combination of morphologic and compositional characters is also present in some species of modern single-chambered agglutinated tubular foraminiferans, and is not found in other agglutinated eukaryotes. ...... (ABSTRACT)
Bosak, T., Lahr, D.J.G., Pruss, S.B., Macdonald, F.A., Gooday, A.J., Dalton, L., Matys, E.D., 2011. Possible early foraminiferans in post-Sturtian (716−635 Ma) cap carbonates. Geology 40 (1), 67--70.
ARCTIC FRONT SHIFTS IN THE SUBPOLAR NORTH ATLANTIC DURING THE MID-PLEISTOCENE
Surface water conditions at the Integrated Ocean Drilling Program (IODP) Site U1314 (Southern Gardar Drift, 56° 21.8′ N, 27° 53.3′ W, 2820 m depth) were inferred using planktic foraminifer assemblages between Marine Isotope Stage (MIS) 19 and 11 (ca. 800–400 ka). Factor analysis of the planktic foraminifer assemblages suggests that the assemblage was controlled by three factors. The first factor (which explained 49% of the variance) is dominated by transitional and subpolar species and points to warm and salty surface water conditions (Atlantic water). The second factor (37%) is dominated by Neogloboquadrina pachyderma sin and has been associated with the presence of cold and low saline surface waters (Arctic water). Finally, the third factor (9%), linked to a significant presence of Turborotalita quinqueloba, reflects the closeness of the Arctic front (the boundary between Atlantic and Arctic water). The position of the Arctic and Polar fronts has been estimated across the glacial–interglacial cycles studied according to planktic foraminifer abundances from Site U1314 (and their factor analysis) combined with a synthesis of planktic foraminiferand diatom data from other North Atlantic sites. ......
► Planktic foraminifer assemblages were used to study changes in surface water masses. ► Arctic front position and North Atlantic surface circulation was tracked (800–400 ka). ► Changes in surface circulation were related to changes in deep circulation. ► Climatic cycles were divided in five phases. (ABSTRACT)
Alonso-Garcia, M., Sierro, F.J., Flores, A.A., 2011. Arctic front shifts in the subpolar North Atlantic during the Mid-Pleistocene (800–400 ka) and their implications for ocean circulation. Palaeogeography, Palaeoclimatology, Palaeoecology 311 (3--4), 268--280.
SEA SURFACE TEMPERATURE RANGES OF THE ARABIAN SEA FOR THE PAST 20kyr
...... Here we present the oxygen isotope composition of individual specimens of the surface-dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabian Sea off Somalia, inferred as indicators of past seasonal ranges in temperature. Combining the δ18O measurements of individual specimens to obtain temperature ranges with Mg/Ca based mean calcification temperatures allows us to reconstruct temperature extrema. Our results indicate that over the past 20 kyr the seasonal temperature range has fluctuated from its present value of 16 °C to mean values of 13 °C and 11 °C for the Holocene and LGM, respectively. The data for the LGM suggest that the maximum temperature was lower, whilst minimum temperature remained approximately constant. The rather minor variability in lowest summer temperatures during the LGM suggests roughly constant summer monsoon intensity, while upwelling-induced productivity was lowered.
Ganssen, G.M., Peeters, F.J.C., Metcalfe, B., Anand, P., Jung, S.J.A, Kroon, D., Brummer, G.-J., A., 2011. Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years. Climate of the Past 7, 1337--1349, doi:10.5194/cp-7-1337-2011
CARBONIFEROUS FORAMINIFERAL BIOSTRATIGRAPHY IN ADAROUCH, CENTRAL MOROCCO
The Carboniferous succession in Adarouch (Central Morocco, north of the Atlas Transform Fault) contains thick carbonate beds including upper Visean, Serpukhovian and basal Bashkirian rocks. Foraminifers enable precise recognition of the Visean/Serpukhovian (V/S), early/late Serpukhovian (eS/lS) and Serpukhovian/Bashkirian (S/B) boundaries. Insolentitheca horrida, Loeblichia ukrainica, “Millerella” spp. and Endostaffella? sp. 2 are regarded as regionally useful indices to the V/S boundary, whereas Eostaffellina spp., Eostaffella pseudostruvei and some evolved species of Archaediscus exhibit greater reliability for worldwide correlation of this level. Similarly, the eS/lS boundary is marked locally by Brenckleina rugosa, Eosigmoilina sp., and Monotaxinoides spp. and globally by Loeblichia minima, Bradyina cribrostomata, Plectostaffella spp., Eostaffellina “protvae” and “Turrispiroides”, and the S/B boundary is marked locally by Globivalulina bulloides and globally by Seminovella elegantula, and Novella?. Occurrences of these taxa in Morocco allow correlations with the Moscow Basin, the Urals, the Donetz Basin and North America. The Moroccan assemblages share few taxa in common with Saharan basins south of the Atlas Transform Fault. Correlations with western European basins are difficult because of the paucity in the latter of foraminiferal-bearing carbonate strata. (ABSTRACT)
Cózar, P., Said, I., Somerville, I.D., Vachard, D., Medina-Varea, P., Rodríguez, S., Berkhli, M., 2011. Potential Foraminiferal Markers for the Visean–Serpukhovian and Serpukhovian–Bashkirian Boundaries—a Case-Study from Central Morocco. Journal of Paleontology 85 (6), 1105--1127.
EXTINCTION OF LARGER BENTHIC FORAMINIFERA AT THE EOCENE/OLIGOCENE BOUNDARY
A number of long-ranging and widespread larger benthic foraminiferal taxa are known to have become extinct during the Eocene–Oligocene transition. However, detailed records through the transition are rare, and few complete sections are known. Here we study an apparently complete section from Tanzania from three drill cores across the Eocene/Oligocene boundary in a hemipelagic clay succession. Within these, larger benthic foraminifera occur dispersed in the clays and concentrated in limestones which occur as secondary debris flow deposits. These cores allow the larger benthic foraminiferal stratigraphy to be tied to planktonic foraminifera and nannofossil biostratigraphy and stable isotope (δ,18O, δ13C) stratigraphy. These records show that all of the larger benthic foraminifera extinction events occur close to the Eocene/Oligocene boundary as recognised by the extinction of the planktonic foraminiferal Family Hantkeninidae, rather than at the prominent oxygen isotope excursion in the lower Oligocene that signifies maximum ice growth and global sea-level fall. This correlation raises questions about the mechanism responsible for the extinctions and has implications for global larger benthic foraminiferal stratigraphy. (ABSTRACT)
Cotton, L.J., Pearson, P.N., 2011. Extinction of larger benthic foraminifera at the Eocene/Oligocene boundary. Palaeogeography, Palaeoclimatology, Palaeoecology 311 (3--4), 281--296.
NEW SPECIES OF ROBERTINIDA FROM THE SLOVENIAN BASIN
Twelve species of genera Diplotremina Kristan-Tollmann, 1960, Duostomina Kristan-Tollmann, 1960, and Variostoma Kristan-Tollmann, 1960 have been described from the Norian and Rhaetian strata of the Slovenian Basin (eastern Southern Alps). A lamellar wall structure has been confirmed for Duostomina and observed for the first time in Variostoma. The multi-layered nature of the lamellae of Diplotremina and Duostomina may be a result of a diagenetic alteration of the single-layered lamellae. The position of Variostoma in the family Duostominidae remains doubtful due to the alveolar nature of its wall. (ABSTRACT)
Gale, L., Rettori, R., Martini, R., Šmuc, A., Kolar-Jurkovšek, T., Rožié, B., 2011. Duostominidae (Foraminiferea, Robertinida) from the Upper Triassic beds of the Slovenian Basin (Southern Alps, Slovenia. Revista Italiana di Paleontologia e Stratigrafia 117 (3).
BACTERIAL CONTROL OF DISSOLUTION IS UNLIKELY
We investigated the ability of bacterial communities to colonize and dissolve two biogenic carbonates (Foraminifera and oyster shells). Bacterial carbonate dissolution in the upper water column is postulated to be driven by metabolic activity of bacteria directly colonising carbonate surfaces and the subsequent development of acidic microenvironments. We employed a combination of microsensor measurements, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and image analysis and molecular documentation of colonising bacteria to monitor microbial processes and document changes in shell surface topography. Bacterial communities rapidly colonised shell surfaces, forming dense biofilms with extracellular polymeric substance (EPS) deposits. Despite this, we found no evidence of bacterially mediated carbonate dissolution. Dissolution was not indicated by Ca2+ microprofiles, nor was changes in shell surface structure related to the presence of colonizing bacteria. Given the short time (days) settling carbonate material is actually in the twilight zone (500–1000 m), it is highly unlikely that microbial metabolic activity on directly colonised shells plays a significant role in dissolving settling carbonates in the shallow ocean. (ABSTRACT)
Bissett, A., Neu, T.R., de Beer, D., 2011. Dissolution of Calcite in the Twilight Zone: Bacterial Control of Dissolution of Sinking Planktonic Carbonates Is Unlikely. PLoS ONE 6 (11): e26404. doi:10.1371/journal.pone.0026404
ELEMENT/CALCIUM RATIOS IN MIDDLE EOCENE Oridorsalis umbonatus
Culturing studies and empirical-based calibrations suggest that elemental ratios in benthic foraminifera can be used as proxies to reconstruct past variations in bottom water temperature and saturation state (Δ[CO32−]). However the mechanism(s) linking elemental ratios to Δ[CO32−] are poorly constrained. We present middle Eocene records of Oridorsalis umbonatus Li/Ca, B/Ca, Mg/Ca and Sr/Ca from Ocean Drilling Program Site 1209. We apply calibrations developed from core top samples to estimate middle Eocene variations in intermediate water Δ[CO32−]. The fidelity of bottom water Δ[CO32−] reconstructions based on single element ratios are assessed by comparing the X/Ca-based reconstructions to each other and to carbon cycle proxy records (benthic foraminifera δ13C, organic carbon content, foraminifera dissolution indices), and a seawater δ18O reconstruction for Site 1209. Discrepancies in the reconstructed Δ[CO32−] values for the middle Eocene based on these different metal ratios suggests that there are still gaps in our understanding of the parameters influencing X/Ca. The downcore record of O. umbonatus Mg/Ca does not exhibit any similarities with the Li/Ca, B/Ca and Sr/Ca records, suggesting that bottom water Δ[CO32−] is not the dominant influence on Mg/Ca ratios for this species. This hypothesis is supported by the coefficients of multiple linear regression models on new and published Mg/Ca data.
Dawber, C.F., Tripati, A.K., 2011. Element/Calcium ratios in middle Eocene samples of Oridorsalis umbonatus from Ocean Drilling Program Site 1209. Climate of the Past Dicussions 7, 3795-3821, doi:10.5194/cpd-7-3795-2011
WORLDWIDE GENOTYPING IN Globoconella inflata
The planktonic foraminiferal morpho-species Globoconella inflata is widely used as a stratigraphic and paleoceanographic index. While G. inflata was until now regarded as a single species, we show that it rather constitutes a complex of two pseudo-cryptic species. Our study is based on SSU and ITS rDNA sequence analyses and genotyping of 497 individuals collected at 49 oceanic stations covering the worldwide range of the morpho-species. Phylogenetic analyses unveil the presence of two divergent genotypes. Type I inhabits transitional and subtropical waters of both hemispheres, while Type II is restricted to the Antarctic subpolar waters. The two genetic species exhibit a strictly allopatric distribution on each side of the Antarctic Subpolar Front. On the other hand, sediment data show that G. inflata was restricted to transitional and subtropical environments since the early Pliocene, and expanded its geographic range to southern subpolar waters ~700 kyrs ago, during marine isotopic stage 17. This datum may correspond to a peripatric speciation event that led to the partition of an ancestral genotype into two distinct evolutionary units. Biometric measurements performed on individual G. inflata from plankton tows north and south of the Antarctic Subpolar Front indicate that Types I and II display slight but significant differences in shell morphology. These morphological differences may allow recognition of the G. inflata pseudo-cryptic species back into the fossil record, which in turn may contribute to monitor past movements of the Antarctic Subpolar Front during the middle and late Pleistocene. (ABSTRACT)
Morard, R., Quillévéré, F., Douady, C.J., de Vargas, C., de Garidel-Thoron, T., Escarguel, G., 2011. Worldwide Genotyping in the Planktonic Foraminifer Globoconella inflata: Implications for Life History and Paleoceanography. PLoS ONE 6 (10): e26665. doi:10.1371/journal.pone.0026665
WHAT SHOULD WE CALL THE FORAMINIFERA?
Shelled granuloreticulose microorganisms have had a complex etymological history that began in 1826 when d’Orbigny gave his new order the name Foraminifères and characterized the group. Soon afterwards, further examination and proper Latinization established them as class Foraminifera. D’Orbigny should be credited with the suprafamilial group name, regardless of rank, because he provided defining characteristics, and also because higher taxa are not governed by ICZN rules; in addition, we should consider the history of its attribution and what is traditional and customary in zoological nomenclature. The name Foraminifera is the source of a variety of informal terms, including foraminifera, foraminifer, foraminiferan, and for-am. Long after being demoted to order, the Latinized name was modified to Foraminiferida in 1964 by Loeblich and Tappan, the informal foraminiferid was introduced later. Here, we briefly examine these terms as sets of singular and plural nouns, and their derived adjectives and nouns that begin with foram-. Authors can choose any of the derived terms, but they should be consistent by using only one term-set throughout their paper. Other nouns derived from foraminifer-, such as foraminiferologist for a student of the group, are not usually part of a term-set.
The informal term foram is a valid derivation and it is the most common of the names used in conversation among earth scientists and biologists. It is already accepted in major dictionaries and literature, and it has been used in specific word pairs found in scientific publications. In addition, foram eases communication by its multilingual applicability; it is also the easiest of the terms to pronounce, write, and read. For all these reasons, its use may increase in scientific literature. (ABSTRACT)
Lipps, J.H., Finger, K.L., Walker, S.E., 2011. What should we call the Foraminifera?. Journal of Foraminiferal Research 41 (4), 309--313.
PHOTOSYNTHESIS AND RESPIRATION IN FIVE SPECIES OF BENTHIC FORAMINIFERA
Oxygen production and consumption were measured in five species of benthic foraminifers using a "Clark-type" oxygen electrode. Net photosynthesis and respiration were calculated and normalized to μg chlorophyll a for the chlorophyte-bearing soritid foraminifers Archaias (Ar.) angulatus and Cyclorbiculina compressa, and the diatom-bearing amphisteginids Amphistegina gibbosa, Am. lessonii, and Am. radiata. ...... Median factorial metabolic scope, which is the ratio of respiration rate under normal activity to resting metabolic rate, was 2–4 for the amphisteginids versus 9–10 for the soritids. Archaias angulatus, C. compressa and Am. lessonii appear to be net primary producers, whereas Am. gibbosa and Am. radiata are net consumers. (ABSTRACT)
Walker, R.A., Hallock, P., Torres, J.J., Vargo, G.A., 2011. Photosynthesis and respiration in five species of benthic oraminifea that host algal endosymbionts. Journal of Foraminiferal Research 41 (4), 314--325.
BENTHONIC FORAMINFIEAL PALEOECOLOGY OF THE PLEOSTOCENE, EASTERN CARIBBEAN SEA
Deep Sea Drilling Project Hole 148 was drilled on the Aves Ridge, eastern Caribbean Sea at a lower-bathyal depth (1232 m) beneath the eastern edge of the Orinoco plume. The drillhole penetrated ~124 m of Pleistocene sediment, but core recovery was poor (66%). From 62 samples taken at ~2-m intervals, 17,259 >105-μm benthonic foraminifera were picked and 212 species were identified. ...... Species of Uvigerina and Bulimina, indicative of organic loading and low dissolved-oxygen content, respectively formed 22.6% and 14.3% of total recovery. Cibicidoides bradyi formed 4.4% of total recovery and Globocassidulina subglobosa 3.3%. This indicates that, although the Caribbean Sea is bordered to the north, east, and west by oligotrophic waters, the Pleistocene in DSDP Hole 148 was deposited under organic-rich, low-oxygen conditions. ...... The Stilostomella Extinction, in which uniserial foraminifera decreased through the section, occurred through a gradual loss of specimens. (ABSTRACT)
WILSON, B., COSTELLOE, A, 2011. Photosynthesis and respiration in five species of benthic oraminifea that host algal endosymbionts. Journal of Foraminiferal Research 41 (4), 363--370.
TESTING THE PROTOZOAN HYPOTHESIS FOR EDIACARAN FOSSILS
The hypothesis that the Ediacara biota were giant protozoans is tested by considering the external morphology, internal organization, suggested fossil representatives and molecular phylogeny of the xenophyophores. From this analysis, we find no case to support a direct relationship. Rather, the xenophyophores are here regarded as a group of recently evolved Foraminifera and are hence unlikely to have a record from the Ediacaran Period. Further from the growth dynamics of Foraminifera, they are also unlikely to be related to the Palaeopascichnus organism. We also find significant distinctions in the growth dynamics of Palaeopascichnus and organisms usually referred to the Ediacara biota, such as Charnia and Dickinsonia. Developmental analysis of the Palaeopascichnus– central to the xenophyophore hypothesis – reveals unusual, protozoan features, including evidence for chaotic repair structures, for mergence of coeval forms, as well as complex bifurcations. These observations suggest that Palaeopascichnus is a body fossil of an unidentified protozoan but is unrepresentative of Ediacaran body construction, in general. (ABSTRACT)
Antcliffe, J.B., Gooday, A.J., Brasier, M.D., 2011. Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis of Palaeopascichnus. Palaeontology 54 (5), 1157--1175.
BIOSTRATIGRAPHY AND PALEOENVIRONMENT OF THE ALBIAN-TURONIAN IN CÔTE D'IVOIRE
The deposits of Albian-Turonian age from an interval 3702 m - 2430 m of an oil well located within the Abidjan margin are described under a triple plan (lithological, micropaleontological and paleoenvironmental), based on study of 136 cuttings samples. Three lithologic units are identified, consisting mainly of gray shales, with a relatively poor microfauna dominated by planktonic foraminifera, coupled with calcispherid (especially in the upper range). Five intervals are identified namely : Early to Middle Albian (3702 m - 2871 m), Late Albian (2871 m - 2550 m), Cenomanian (2550 m - 2502 m), Turonian (2502 m - 2430 m) and, tentatively, Early Senonian (2430 m - 2421 m). The depositional environments range from an inner shelf under continental influence (from the Late to Middle Albian) to the outer platform (Late Turonian) in conjunction with the progressive deepening phase of Ivorian margin related to marine fluctuations occurred during Mid-Cretaceous in the northern Gulf of Guinea.
Bamba, K.M., Digbehi, B.Z., Sombo, C.B., Goua, E.T., N'Da, V.L., 2011. Foraminifères planctoniques, biostratigraphie et paléoenvironnement des dépôts albo-turoniens de la Côte d’Ivoire, Afrique de l’Ouest. Revue de Paléobiologie 30 (1), 1--11.
RESPONSE OF ABYSSAL FORAMINIFERA TO A SIMULATED PHOTODETRITUS PULSE
...... We investigated benthic foraminifera at Station M (4000 m depth) in the Northeast Pacific and assessed the response of individual species to a simulated phytodetritus pulse during an in situ feeding experiment. Sediments were incubated for 4 d with 13C-labeled diatoms (Thalassiosira weissflogii) applied to the sediment surface. The living foraminiferal community (>0.063 mm) of the upper 3 cm contained >100 species and was strongly dominated by a few taxa of soft-walled saccamminids. ...... Large differences were observed in the uptake of the algal material among species and between depth levels. During the experiment, 0.82 mg C m−2 were ingested, mainly by calcareous (~60%) and agglutinated (~40%) foraminifera. Uptake was highest at the sediment surface and 3 to 5 times less in deeper sediment horizons. Despite clear signs of vitality and a strong representation in the foraminiferal community, none of the soft-walled species showed a noticeable response to the offered algal material. We conclude that soft-walled foraminifera may not be important to the short-term phytodetrital matter cycling at the abyssal sea floor.
Enge, A.J., Nomaki, H., Ogawa, N.O., Witte, U., Moeseneder, M.M., Lavik, G., Ohkouchi, N., Kitazato, H., Heinz, P., 2011. Response of the benthic foraminiferal community to a simulated short-term phytodetritus pulse in the abyssal North Pacific. Marine Ecology Progress Series 438, 129--142.
EXPERIMENTAL ASSEMBLAGES FROM PROPAGULE BANKS
...... The recent discovery of foraminiferal propagule banks that occur in the fine-sediment fraction of marine depositional settings provides a novel experimental tool for examining the ecology of benthic foraminifera, their processes of dispersal, and the responses of multi-species assemblages to changing environmental conditions. In the ‘propagule method’ presented here, we use experimental arrays in which foraminifera are grown from propagule banks under different controlled abiotic conditions. We examined the roles of temperature, salinity, and site (exposed vs. protected) in structuring coastal assemblages and show that, because individual species respond differently, distinct assemblages grew from the same propagule bank under different environmental regimes. Temperature was the most important factor distinguishing experimental assemblages, whereas exposure of the collection site (e.g. to waves and currents, that promote or limit species dispersal to and from each site) was most important in determining species richness. The diversity of the propagule bank therefore imparts resilience to foraminiferal associations and provides a rapid-response mechanism for changing environments. This method further provides a tool for documenting changes in coastal assemblages that potentially result from warming or cooling climates. (ABSTRACT)
Goldstein, S., Alve, E.,, 2011. Experimental assembly of foraminiferal communities from coastal propagule banks. Marine Ecology Progress Series 437, 1--11.
DIFFERENT UTILIZATION OF PARTICULATE AND DISSOLVED ORGANIC MATTER
The fate of particulate and dissolved organic carbon in deep-sea benthic organisms was evaluated by in situ 13C-labeling experiments in the central part of Sagami Bay, Japan (water depth: 1453 m). 13C-labeled glucose and Chlorella sp. (Chlorophyta) were injected into a series of in situ culture cores and incubated for 0 to 9 d. Glucose was chosen as an example of labile dissolved organic matter in the pore water, and Chlorella sp. as an example of fresh algal material. Incorporation of both carbon sources by benthic foraminifera and metazoans was determined based on enrichment in 13C of their bulk tissues. Archaeal incorporations were also evaluated by examining 13C-labeled lipid biomarkers. ...... Labile dissolved organic matter may serve as an accessible food source for benthic organisms and is quickly mineralized on the deep seafloor.
Nomaki, H., Ogawa, N.O., Takano, Y., Suga, H., Ohkouchi, N., Kitazato, H., 2011. Differing utilization of glucose and algal particulate organic matter by deep-sea benthic organisms of Sagami Bay, Japan. Marine Ecology Progress Series 431, 11--24.
BIOSTRATIGRAPHY FOR THE UPPER CRETACEOUS VOLCANOCLASTIC-SEDIMENTARY FORMATIONS
The biostratigraphy of the Upper Cretaceous volcanoclastic-sedimentary formations cropping out in the Timok Eruptive Area of the eastern Serbian Carpatho-Balkanides is presented. Four lithostratigraphic units of formation rank are recognized in the Timok area: Stublica Clastics (Upper Albian/Cenomanian), Ostrelj (Lower Turonian/Santonian), Bor Clastics (Campanian/Maastrichtian) and Bukovo (Campanian/?Maastrichtian). Forty two species of planktonic foraminifera have been determined in the studied area. Eight planktonic foraminiferal zones of Middle Cenomanian through Middle Campanian age have been recognized. ...... The scarcity or lack of zonal species in the Lower Cenomanian and Upper Campanian/Maastrichtian strata prevents recognition of the nominal zones. The Upper Cretaceous planktonic foraminiferal zones from the Timok Eruptive Area are correlated with coeval zones from adjacent regions of Bulgaria and Romania and from other Tethyan regions.
Ljubovic-Obradovic, D., Carevic, I., Mirkovic, M., Protic, N., 2011. Upper Cretaceous volcanoclastic-sedimentary formations in the Timok Eruptive Area (eastern Serbia): new biostratigraphic data from planktonic foraminifera. Geologica Carpathica 62 (5), 435--446.
IMPACT OF CARBONATE ION CONCENTRATION ON Mg and Sr INCORPORATION
Laboratory culture experiments were conducted to determine effects of seawater carbonate ion concentration ([CO32−]), and thereby calcite saturation state (Ω), on Mg and Sr incorporation into calcite of two species of shallow-water benthic foraminifera: Ammonia tepida and Heterostegina depressa. Impact on Mg and Sr incorporation by increased seawater [CO32−] and thereby higher Ω is absent in either species. Comparison to results from a similar culturing experiment, in which Ω was varied as a function of [Ca2+], reveals that saturation state affects incorporation of Mg and Sr through calcium—rather than carbonate availability. The similarity in response by both species is surprising since the average Mg/Ca ratio is ~ 70 times higher in H. depressa than in A. tepida. Furthermore, these results suggest that the ions involved in biomineralization (i.e. Ca2+ and DIC) are processed by separate cellular transport mechanisms. The similar response of Mg and Sr incorporation in this study suggests that only differences in the Ca2+ transport mechanism affect divalent cation partitioning.
Dueñas-Bohórquez, A., Raitzsch, M., de Nooijer, L.J., Reichart, G-J., 2011. Independent impacts of calcium and carbonate ion concentration on Mg and Sr incorporation in cultured benthic foraminifera. Marine Micropaleontology 81 (3–4), 122--130, doi:10.1016/j.marmicro.2011.08.002.
LATE CRETACEOUS LARGER FORAMINIFERA AND Sr ISOTPE STRATIGRAPHY
The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary. ...... By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.
Highlights ► We describe the larger forams of the La Cova Limestones (Cretaceous, Pyrenees). ► We use Sr isotope stratigraphy for high resolution dating and correlation. ► The La Cova Limestones are early Coniacian to early-middle Santonian boundary. ► The first assemblage of larger forams appears at the e-m Coniacian boundary. ► The second assemblage appears in the earliest Santonian. (ABSTRACT)
Boix, C., Frijia, G., Vicedo, V., Bernaus, J.M., Di Lucia, M., Parente, M., Caus, E., 2011. Larger foraminifera distribution and strontium isotope stratigraphy of the La Cova limestones (Coniacian–Santonian, “Serra del Montsec”, Pyrenees, NE Spain). Cretaceous Research 32 (6), 806--822, doi:10.1016/j.cretres.2011.05.009
OLDEST ORDOVICIAN FORAMINIFERA IN SOUTH AMERICA
The oldest occurrences of the monothalamous foraminifer species Amphitremoida longa Nestell and Tolmacheva and A. laevis Nestell and Tolmacheva are found in the San Juan Formation together with conodonts of the Oepikodus evae Zone of the Floian (Lower Ordovician), in the Salagasta 2 section, southern Precordillera, Argentina. These discoveries also represent the oldest record for foraminifers in South America. The foraminifers, species of which were originally described from the Lower Ordovician of northwestern Russia, are found in shallow high energy carbonate platform deposits in the Precordillera, together with a North Atlantic province conodont fauna. The carbonate sequence of the San Juan Formation in the Salagasta region is interpreted as a succession ranging from shallower tidal deposits to carbonate crinoidal shoaling bar deposits. (ABSTRACT)
Nestel, G., Heredia, S., Mestre, A., Beresi, M., González, M., 2011. The oldest Ordovician foraminifers (Oepikodus evae conodont Zone, Floian) from South America. Geobios, doi:10.1016/j.geobios.2011.02.007
DIVERSITY-DEPENDENCE MODEL WITH EXTINCTION FOR MACROEVOLUTIONARY DYNAMICS
The branching times of molecular phylogenies allow us to infer speciation and extinction dynamics even when fossils are absent. Troublingly, phylogenetic approaches usually return estimates of zero extinction, conflicting with fossil evidence. Phylogenies and fossils do agree, however, that there are often limits to diversity. Here, we present a general approach to evaluate the likelihood of a phylogeny under a model that accommodates diversity-dependence and extinction. We find, by likelihood maximization, that extinction is estimated most precisely if the rate of increase in the number of lineages in the phylogeny saturates towards the present or first decreases and then increases. We demonstrate the utility and limits of our approach by applying it to the phylogenies for two cases where a fossil record exists (Cetacea and Cenozoic macroperforate planktonic foraminifera) and to three radiations lacking fossil evidence (Dendroica, Plethodon and Heliconius). We propose that the diversity-dependence model with extinction be used as the standard model for macro-evolutionary dynamics because of its biological realism and flexibility. (ABSTRACT)
Etienne, R.S., Haegeman, B., Stadler, T., Aze, T., Pearson, P.N., Purvis, A., Phillimore, A.B., 2011. Diversity-dependence brings molecular phylogenies closer to agreement with the fossil record. Proceedings of the Royal Society B, doi: 10.1098/rspb.2011.1439
CAMPANIAN-MAASTRICHTIAN BIOSTRATIGRAPHY OF THE MONI FM. IN SOUTHERN CYPRUS
The first data on the taxonomic composition and stratigraphic range of the late Campanian planktonic foraminifers encountered in the middle and upper parts of the Moni Formation, southern Cyprus, are reported. ...... The planktonic foraminiferal assemblages discussed are referred to the Globotruncana aegyptiaca Zone and to the lowermost Gansserina gansseri Zone of the upper upper Campanian of the standard scale. The intraregional correlation of the Moni sections, depth of erosion of the upper part of the formation, and its relationship with the Kannaviou Formation have been refined. ...... For tracing the Campanian-Maastrichtian boundary (GSSP), attention should be paid to the LADs of Globotruncana bulloides and Contusotruncana fornicata and the potential use of Globotruncanita (Elevatotruncana) eolita sp. nov. should be assessed. It is shown that subfamily Archaeoglobigerininae Salaj, 1987, emend. O. Korchagin is the older synonym of subfamily Archaeoglobigerininae Georgescu, 2005. Two poorly known and three new planktonic foraminiferal species are described. (ABSTRACT)
Korchagin, O.A., 2011. Upper Campanian-lower Maastrichtian planktonic foraminifers and biostratigraphy of the Moni Formation, southern Cyprus. Stratigraphy and Geological Correlation 19 (5), 526--544.
MIOCENE-PLIOCENE LARGER FORAMINIFERA AN DEPOSITIONAL ENVIRONMENTS OF CARBONATE BANK
In this paper we present first results of the study of planktonic Foraminifera, large benthic Foraminifera and carbonate facies of La Désirade, aiming at a definition of the age and depositional environments of the Neogene carbonates of this island. The study of planktonic Foraminifera from the Detrital Offshore Limestones (DOL) of the Ancienne Carrière allows to constrain the biochronology of this formation to the lower Zone N19 and indicates a latest Miocene to early Pliocene (5.48–4.52 Ma) age. Large benthic Foraminifera were studied both as isolated and often naturally split specimens from the DOL, and in thin sections of limestones from the DOL and the Limestone Table (LT). ...... The rhythmic deposition of the Désirade Limestone Table (LT) can be explained by synsedimentary subsidence in a context of rapidly oscillating sea-level due to precession-driven (19–21 kyr) glacio-eustatic sea-level changes during the latest Miocene-Pliocene. Except for a thin reef cap present at the eastern edge of the LT, no other in-place reefal constructions have been observed in the LT. The DOL of western Désirade are interpreted as below wave base gravity deposits that accumulated beneath a steep fore-reef slope. They document the mobilisation of carbonate material (including Larger Foraminifera) from an adjacent carbonate platform by storms and their gravitational emplacement as debris and grain flows. The provenance of both the reefal carbonate debris and the tuffaceous components redeposited in the carbonates of La Désirade must be to the west, i.e. the carbonate platforms of Marie Galante and Grande Terre. (ABSTRACT)
Baumgartner-Mora, C., Boumgartner, P.O., 2011. Latest Miocene-Pliocene Larger Foraminifera and depositional environments of the carbonate bank of La Désirade Island, Guadeloupe (French Antilles). Revue de Micropaléontologie, doi:10.1016/j.revmic.2011.08.002
HIGH LATITUDE REGULATION OF LOW LATITUDE THERMOCLINE VENTILATION
One of the earliest discoveries in palaeoceanography was the observation in 1935 that the (sub)tropical planktic foraminifer Globorotalia menardii became absent or extremely rare in the Atlantic Ocean during glacials of the late Pleistocene. Yet a mechanistic explanation for G. menardii 's extraordinary biogeographic behaviour has eluded palaeoceanographers for 75 years. Here we show that modern G. menardii, along with two other species that also suffer Atlantic population collapses during glacials, track poorly ventilated waters globally in their thermocline habitats. The ventilation states of low latitude thermoclines are ‘set’, to a first order, by intermediate water masses originating at high latitudes. In the modern Atlantic this control on low latitude thermocline ventilation is exerted by relatively poorly ventilated, southern-sourced Antarctic Intermediate Water (AAIW) and sub-Antarctic Mode Water (SAMW). We suggest that the glacial Atlantic foraminifer population collapses were a consequence of a low latitude thermocline that was better ventilated during glacials than it is today, in line with geochemical evidence, and driven primarily by a well-ventilated, northern-sourced intermediate water mass. A ventilation mechanism driving the glacial population collapses is further supported by our new constraints on the precise timing of these species' Atlantic proliferation during the last deglaciation — occurring in parallel with a wholesale, bipolar reorganisation of the Atlantic's thermocline-to-abyssal overturning circulation. Our findings demonstrate that a bipolar seesaw in the formation of high latitude intermediate waters has played an important role in regulating the population dynamics of thermocline-dwelling plankton at lower latitudes. (ABSTRACT)
Sexton, P.F., Norris, R.D., 2011. High latitude regulation of low latitude thermocline ventilation and planktic foraminifer populations across glacial–interglacial cycles. Earth and Planetary Science Letters, doi:10.1016/j.epsl.2011.08.044
REPEATED BOTTOM-WATER OXYGENATION DURING OAE 2
...... We have generated X-ray fluorescence elemental concentration and benthic foraminiferal assemblage records for a short section of OAE 2 black shales from Wunstorf, northern Germany. Two intervals of low sulphur elemental concentration are interpreted as periods of increased oxygenation of bottom waters. This is supported by benthic foraminiferal assemblage data showing repopulation events associated with these intervals. These repopulation events are characterized mainly by the occurrence of agglutinated taxa, with Lingulogavelinella globosa being the only abundant calcareous species. This observation is interpreted in terms of short-term interruptions of the otherwise anoxic bottom-water environment. Comparison with repopulation events during OAE 1b and Quaternary sapropels make it reasonable to speculate that short-term cooling and an associated increase in bottom-water ventilation at the NW European shelf sea are the main trigger mechanisms for the observed repopulation events at Wunstorf. As source area for benthic foraminifera, shallower parts of the Lower Saxony basin are proposed. (ABSTRACT)
Friedrich, O., Voigt, S., Kuhnt, T., Koch, M.C., 2011. Repeated bottom-water oxygenation during OAE 2: timing and duration of short-lived benthic foraminiferal repopulation events (Wunstorf, northern Germany). Journal of Micropalaeontology 30 (2), 119--128.
LATEST DANIAN EVENT AT GEBEL QREIYA, EASTERN DESERT, EGYPT
The Latest Danian Event (LDE) is a proposed early Palaeogene transient warming event similar to the Paleocene–Eocene Thermal Maximum, albeit of smaller magnitude. The LDE can be correlated with a carbon isotope excursion (‘CIE-DS1’) at Zumaia, Spain, and the ‘top Chron C27n event’ defined recently from ocean drilling sites in the Atlantic and Pacific, supporting a global extent. Yet, records of environmental change during the LDE (e.g. warming and sea-level fluctuations) are still rare. In this study, we focus on the micropalaeontology (calcareous nannofossils and benthic foraminifera), mineralogy and trace element geochemistry of the LDE in the Qreiya 3 section from the southern Tethyan margin in Egypt. ......
Sprong, J., Youssef, M.A., Bornemann, A., Schulte, P., Steurbaut, E., Stassen, P., Kouwenhoven, T.J., Speijer, R.P., 2011. A multi-proxy record of the Latest Danian Event at Gebel Qreiya, Eastern Desert, Egypt. Journal of Micropalaeontology 30 (2), 167--182.
MODERN AND PLEISTOCENE B/Ca RATIOS OF Planulina wuellerstorfi
...... B/Ca ratios of the benthic foraminifer Planulina wuellerstorfi from South Atlantic core top samples have been analyzed using laser ablation–inductively coupled plasma–mass spectroscopy (LA-ICP-MS) to provide additional information on intratest trace element heterogeneity. Results show that boron is heterogeneously distributed within and between shells, with content variations of approximately ±43% displayed within a single shell. ...... Despite this heterogeneity, mean B/Ca ratios are positively correlated with the deepwater calcite saturation state (Δ[CO32−]), in line with previous studies. We apply this empirical relationship to reconstruct Δ[CO32−] for the late Pleistocene to Holocene using samples from a depth transect in the equatorial Atlantic. Reconstructed Δ[CO32−] values confirm previous studies suggesting that CaCO3-oversaturated North Atlantic Deep Water was reduced during glacial periods, whereas CaCO3-undersaturated Antarctic Bottom Water expanded vertically and propagated northwards. In summary, our data demonstrate that bulk B/Ca in P. wuellerstorfi reliably reflects variations in Δ[CO32−], despite the strong physiological control of boron incorporation.
Raitzsch, M., Hathorne, E.C., Kuhnert, H., Groeneveld, J., Bickert, T., 2011. Modern and late Pleistocene B/Ca ratios of the benthic foraminifer Planulina wuellerstorfi determined with laser ablation ICP-MS. Geology 39 (11), 1039--1042.
FLUCTUATIONS OF THE OMZ AT THE END OF OAE2
The latest Cenomanian to early Turonian (Late Cretaceous) section at Vallecillo, Mexico, contains a continuous and highly fossiliferous sedimentary record across the late Oceanic Anoxic Event (OAE) 2, and shows similar distributions of benthic inoceramids and planktic foraminifers during this period of an expanded oxygen minimum zone (OMZ). We suggest that these synchronous abundance changes result from similar environmental vulnerability of planktotrophic larval stages of inoceramids and deeper-dwelling planktic foraminifers, and that these synchronous changes reflect the expansion of the OMZ. The abundances of ammonites and fishes, used as independent control groups, do not correlate and rule out a preservational bias. Ammonites, fishes, and their hatchlings thus populated shallower water depths than inoceramid gametes and planktic foramininifers. The improving conditions at the end of OAE 2 resulted in the dispersal of new inoceramid and foraminiferal morphotypes.
Ifrim, C., Götz, S., Stinnesbeck, W., 2011. Fluctuations of the oxygen minimum zone at the end of Oceanic Anoxic Event 2 reflected by benthic and planktic fossils. Geology 39 (11), 1043--1046.
COASTAL POLLUTION MONITORING IN THE PORT OF BOULOGNE-SUR-MER (N FRANCE)
...... A study of both living (Rose Bengal stained) and dead foraminifera was carried on 317 sediment samples collected in the port of Boulogne-sur-Mer (France). Here we present an initial status report on the port ecosystem as recorded from a selected set of sediment samples that cover the full range of habitats within the port. A surprisingly high diversity assemblage of benthic foraminifera was recovered, reflecting the varied habitats within the port. Among the total of 82 species recorded, 34 were found alive (rose Bengal stained). Four key species were identified as potential bioindicators and analyzed with regard to their distribution and correspondence with environmental parameters (sediment grain size, organic carbon content and heavy metal concentration, Cr, Cu and Zn). The benthic foraminifera Haynesina germanica and Bolivina pseudoplicata were found to live particularly well within the innermost parts of the port basins where the highest concentrations of organic carbon and heavy metals occur. Elphidium excavatum and E. magellanicum are well represented in the external parts of the port and can be considered as indicators that tolerate certain threshold values of pollution and environmental stress. As the port is located in an estuarine setting, the relationship between the key indicator taxa for pollution and natural environment is discussed. This study emphasizes the need to address the anthropogenic impact on coastal environments by screening the ubiquitous record of foraminiferal protists as precision tools for bio-monitoring.
du Châtelet, E.A., Gebhardt, K., Langer, M.R., 2011. Coastal pollution monitoring: Foraminifera as tracers of environmental perturbation in the port of Boulogne-sur-Mer (Northern France). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 262 (1), 91--116.
A PROXY FOR CENOZOIC BOTTOM WATER CARBONATE SATURATION
We present modern B/Ca core-top calibrations for the epifaunal benthic foraminifer Nuttallides umbonifera and the infaunal Oridorsalis umbonatus to test whether B/Ca values in these species can be used for the reconstruction of paleo-Δ[CO32−]. O. umbonatus originated in the Late Cretaceous and remains extant, whereas N. umbonifera originated in the Eocene and is the closest extant relative to Nuttallides truempyi, which ranges from the Late Cretaceous through the Eocene. We measured B/Ca in both species in 35 Holocene sediment samples from the Atlantic, Pacific and Southern Oceans. B/Ca values in epifaunal N. umbonifera (~ 85–175 μmol/mol) are consistently lower than values reported for epifaunal Cibicidoides (Cibicides) wuellerstorfi (130–250 μmol/mol), though the sensitivity of Δ[CO32−] on B/Ca in N. umbonifera (1.23 ± 0.15) is similar to that in C. wuellerstorfi (1.14 ± 0.048). In addition, we show that B/Ca values of paired N. umbonifera and its extinct ancestor, N. truempyi, from Eocene cores are indistinguishable within error. In contrast, both the B/Ca (35–85 μmol/mol) and sensitivity to Δ[CO32−] (0.29 ± 0.20) of core-top O. umbonatus are considerably lower (as in other infaunal species), and this offset extends into the Paleocene. Thus the B/Ca of N. umbonifera and its ancestor can be used to reconstruct bottom water Δ[CO32−], whereas O. umbonatus B/Ca appears to be buffered by porewater [CO32−] and suited for constraining long-term drift in seawater B/Ca.
Brown, R.E., Anderson, L.D., Thomas, E., Zachos, J.C., 2011. A core-top calibration of B/Ca in the benthic foraminifers Nuttallides umbonifera and Oridorsalis umbonatus: A proxy for Cenozoic bottom water carbonate saturation. Earth and Planetary Science Letters, doi:10.1016/j.epsl.2011.08.023
MEDIEVAL WARMING PERIOD & RECENT WARMING IN THE GULLMAR FJORD, SWEDEN
A high-resolution study of benthic foraminiferal assemblages was performed on a ca. eight meter long sediment core from Gullmar Fjord on the west coast of Sweden. The results of 210Pb- and AMS 14 C -datings show that the record includes the two warmest climatic episodes of the last 1500 years: the Medieval Warm Period (MWP) and the recent warming of the 20th century. Both periods are known to be anomalously warm and associated with positive NAO winter indices. Benthic foraminiferal successions of both periods are compared in order to find faunal similarities and common denominators corresponding to past climate changes. ...... Judging from dominance of species sensitive to hypoxia and the highest faunal diversity for the last ca. 2400 years, the foraminiferal record of the MWP suggests an absence of severe low oxygen events. At the same time, faunas and δ13C values both point to high primary productivity and/or increased input of terrestrial organic carbon into the fjord system during the Medieval Warm Period. ...... The thin-shelled foraminifer Nonionella iridea was characteristic of the MWP, but became absent during the second half of the 20th century. The recent Skagerrak-Kattegat fauna was rare or absent during the MWP but established in Gullmar Fjord at the end of the Little Ice Age or in the early 1900s. Also, there are striking differences in the faunal diversity and absolute abundances of foraminifera between both periods. Changes in primary productivity, higher precipitation resulting in intensified land runoff, different oxygen regimes or even changes in the fjord's trophic status are discussed as possible causes of these faunal differences.
Polovodova, I., Nordberg, K., Filipsson, H.L., 2011. The benthic foraminiferal record of the Medieval Warm Period and the Recent Warming in the Gullmar Fjord, Swedish west coast. Marine Micropaleontology, doi:10.1016/j.marmicro.2011.09.002