Mechanisms forcing abrupt fluctuations of the Indian Ocean Summer Monsoon during the last deglaciation

A piston core from the Somali upwelling area has been studied at high resolution for its dinoflagellate cyst content. Variations in cyst association are inferred to reflect changes in Indian Ocean summer monsoon intensity. Several abrupt fluctuations in monsoon intensity are detected for the interval between 20 and 10 ka BP. Comparison of these fluctuations with changes in contrast between 30°N and 30°S July insolation and the

Infra red spectroscopy, flash pyrolysis, thermally assisted hydrolysis and methylation (THM) in the presence of tetramethylammonium hydroxide (TMAH) of cultured and sediment-derived Lingulodinium polyedrum (Dinoflagellata) cyst walls

The macromolecular composition of dinoflagellate cyst walls is poorly understood and is usually referred to as ‘sporopollenin-like’. We have carried out micro-Fourier transform infra red (micro-FTIR) analysis of chemically untreated sediment-derived and enzymatically and chemically purified culture-derived Lingulodiniumpolyedrum cyst walls, which suggests an aliphatic polymer rich in C-O bonds and relatively poor in CH2 and CH3 groups, and which is much closer to cellulose than to sporopollenin or algaenan. This is in agreement with flash pyrolysis–gas chromatography–mass spectrometry (py–GC–MS), with and without tetramethylammonium hydroxide (TMAH) of purified culture derived cyst walls, which indicated an oxygen-rich polymer without normal or isoprenoid carbon chains.The results support a strongly cross-linked carbohydrate-based polymer and as such confirm earlier hypotheses that the cysts were unlike algaenan or sporopollenin, contrasting with the suggestion that the cyst walls were highly aromatic and contained tocopherol as a major monomeric building block

Average process length variation of the marine dinoflagellate cyst <i>Operculodinium centrocarpum</i> in the tropical and Southern Hemisphere Oceans: Assessing its potential as a palaeosalinity proxy

The study investigates the morphological variability of the dinoflagellate cyst Operculodinium centrocarpum (resting cyst of Protoceratium reticulatum) in core-top samples distributed over the Southern Hemisphere and the tropics in relation to sea-surface temperature (SST) and sea-surface salinity (SSS) at the corresponding sites. The process lengths show a moderate inverse relationship to summer SST (sSST) (R²=0.44) and sSSS/sSST (R²=0.4), however, lateral transport of cysts probably produced noise in the plots. After excluding tropical and Southern Hemisphere sites considered to have been affected by long distance lateral transport, the relationship between process length and density follows the equation sD=0.8422x+1016.9 (R²=0.55) with a Root Mean Square Error=0.63 kg m-3, while the negative correlation with sSST increases up to R²=0.79. Next to salinity, this study thus highlights the importance of a second factor, temperature, affecting process length in the topics and the Southern Hemisphere oceans

What do SST proxies really tell us? A high-resolution multiproxy (UK`37, TEXH86 and foraminifera δ18O) study in the Gulf of Taranto, central Mediterranean Sea

We present a multiproxy reconstruction of sea surface temperatures (SST) and coastal environmental changes covering the last 600 years on sediments from the Gulf of Taranto, central Mediterranean Sea. The reconstruction is based on UK0 37 (alkenones from haptophytes), TEXH 86 (membrane lipids of marine crenarchaeota), and d18O and d13C of Globigerinoides ruber (white and pink) and of Uvigerina mediterranea. The amplitudes of the temperature signals reconstructed from d18O of G. ruber (white), TEXH 86 and UK0 37 exceed the amplitudes observed in other reconstructions of local and Northern Hemisphere temperature. UK0 37-based SSTs reflect mainly winter/spring conditions with an additional influence of changing nutrient supplies related to water column mixing and runoff. TEXH 86-based temperatures reflect SSTs of the oligotrophic summer season, while influences from near-coastal areas may complicate its interpretation. Co-variation between both lipid-based SST records suggests a common environmental mechanism during the last 600 years. d18O of G. ruber (white) also reflects summer conditions and is amplified by changes in salinity and nutrient availability, which are caused by variations in the relative influence of the Western Adriatic Current (WAC) and of the Ionian Surface Waters (ISW). The combination of SSTTEXH 86 and d18O of G. ruber (white) shows that the circulation in the Gulf of Taranto underwent significant changes during the last 600 year

Establishing an agenda for calcareous dinoflagellates (thoracosphaeraceae, dinophyceae) including a nomenclatural synopsis of generic names

Calcareous dinofoagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decedes with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaelpyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated during the past decade. Over the Years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellagtes, and non-calcareous relatives dervied from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate specualists, we outline major subjects that are in need of re-inivestigatin and-evaluation (an Agenda for Calcareous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates ion a nomenclatural synopsis, with species names indicating their typing and information on type locality and stratigraphy. We Evaluate the status of these names−whether validly published and, if so, whether legitimate−, a crucial first step for any revisionary work in the future

The Glacial–Interglacial transition and Holocene environmental changes in sediments from the Gulf of Taranto, central Mediterranean

An extensive, high-resolution, sedimentological–geochemical survey was done using geo-acoustics, XRF-core scans, ICP-AES, AMS 14C-dating and grain size analyses of sediments in 11 cores from the Gulf of Taranto, the southern Adriatic Sea, and the central Ionian Sea spanning the last 16 cal. ka BP. Comparable results were obtained for cores from the Gallipoli Shelf (eastern Gulf of Taranto), and the southern Adriatic Sea suggesting that the dominant provenance of Gallipoli Shelf sediments is from the western Adriatic mud belt. The 210Pb and 14C-dated highaccumulation-rate sediments permit a detailed reconstruction of climate variability over the last 16 cal. ka BP. Although, the Glacial–Interglacial transition is generally dry and stable these conditions are interrupted by two phases of increased detrital input during the Bølling–Allerød and the late Younger Dryas. The event during the Younger Dryas period is characterized by increased sediment inputs from southern Italian sources. This suggests that run-off was higher in southern- compared to northern Italy. At approximately ~7 cal. ka BP, increased detrital input from the Adriatic mud belt, related to sea level rise and the onset of deep water formation in the Adriatic Sea, is observed and is coincident with the end of sapropel S1 formation in the southern Adriatic Sea. During the mid-to-late Holocene we observed millennial-scale events of increased detrital input, e.g. during the Roman Humid Period, and of decreased detrital input, e.g., Medieval Warm Period. These dry/wet spells are consistent with variability in the North Atlantic Oscillation (NAO). A negative state of the NAO and thus a more advanced penetration of the westerlies into the central Mediterranean, that result in wet conditions in the research area concord with events of high detrital input e.g., during the Roman Humid Period. In contrast, a positive state of the NAO, resulting in dry conditions in the Mediterranean, dominated during events of rapid climate change such as the Medieval Warm Period and the Bronze Age

ON A PSEUDO-DIFFERENT IN AN ALGEBRAIC FUNCTION FIELD OF ONE VARIABLE

An extensive, high-resolution, sedimentological–geochemical survey was done using geo-acoustics, XRF-core scans, ICP-AES, AMS 14C-dating and grain size analyses of sediments in 11 cores from the Gulf of Taranto, the southern Adriatic Sea, and the central Ionian Sea spanning the last 16 cal. ka BP. Comparable results were obtained for cores from the Gallipoli Shelf (eastern Gulf of Taranto), and the southern Adriatic Sea suggesting that the dominant provenance of Gallipoli Shelf sediments is from the western Adriatic mud belt. The 210Pb and 14C-dated highaccumulation-rate sediments permit a detailed reconstruction of climate variability over the last 16 cal. ka BP. Although, the Glacial–Interglacial transition is generally dry and stable these conditions are interrupted by two phases of increased detrital input during the Bølling–Allerød and the late Younger Dryas. The event during the Younger Dryas period is characterized by increased sediment inputs from southern Italian sources. This suggests that run-off was higher in southern- compared to northern Italy. At approximately ~7 cal. ka BP, increased detrital input from the Adriatic mud belt, related to sea level rise and the onset of deep water formation in the Adriatic Sea, is observed and is coincident with the end of sapropel S1 formation in the southern Adriatic Sea. During the mid-to-late Holocene we observed millennial-scale events of increased detrital input, e.g. during the Roman Humid Period, and of decreased detrital input, e.g., Medieval Warm Period. These dry/wet spells are consistent with variability in the North Atlantic Oscillation (NAO). A negative state of the NAO and thus a more advanced penetration of the westerlies into the central Mediterranean, that result in wet conditions in the research area concord with events of high detrital input e.g., during the Roman Humid Period. In contrast, a positive state of the NAO, resulting in dry conditions in the Mediterranean, dominated during events of rapid climate change such as the Medieval Warm Period and the Bronze Age

The Glacial–Interglacial transition and Holocene environmental changes in sediments from the Gulf of Taranto, central Mediterranean

An extensive, high-resolution, sedimentological–geochemical survey was done using geo-acoustics, XRF-core scans, ICP-AES, AMS 14C-dating and grain size analyses of sediments in 11 cores from the Gulf of Taranto, the southern Adriatic Sea, and the central Ionian Sea spanning the last 16 cal. ka BP. Comparable results were obtained for cores from the Gallipoli Shelf (eastern Gulf of Taranto), and the southern Adriatic Sea suggesting that the dominant provenance of Gallipoli Shelf sediments is from the western Adriatic mud belt. The 210Pb and 14C-dated highaccumulation-rate sediments permit a detailed reconstruction of climate variability over the last 16 cal. ka BP. Although, the Glacial–Interglacial transition is generally dry and stable these conditions are interrupted by two phases of increased detrital input during the Bølling–Allerød and the late Younger Dryas. The event during the Younger Dryas period is characterized by increased sediment inputs from southern Italian sources. This suggests that run-off was higher in southern- compared to northern Italy. At approximately ~7 cal. ka BP, increased detrital input from the Adriatic mud belt, related to sea level rise and the onset of deep water formation in the Adriatic Sea, is observed and is coincident with the end of sapropel S1 formation in the southern Adriatic Sea. During the mid-to-late Holocene we observed millennial-scale events of increased detrital input, e.g. during the Roman Humid Period, and of decreased detrital input, e.g., Medieval Warm Period. These dry/wet spells are consistent with variability in the North Atlantic Oscillation (NAO). A negative state of the NAO and thus a more advanced penetration of the westerlies into the central Mediterranean, that result in wet conditions in the research area concord with events of high detrital input e.g., during the Roman Humid Period. In contrast, a positive state of the NAO, resulting in dry conditions in the Mediterranean, dominated during events of rapid climate change such as the Medieval Warm Period and the Bronze Age