Reaction of terrestrial and marine primary producers to abrupt climate changes during the Lateglacial and Holocene of the northeastern Mediterranean : a palynological approach

Für die Analyse klimagesteuerter terrestrischer und mariner Ökosystemdynamik im Spätglazial und Holozän des Ägäisraums wurden terrestrische (Pollen und Sporen) und marine Palynomorphe (organischwandige Dinoflagellatenzysten) aus einem marinen Kern des Berg-Athos-Beckens hochauflösend (d.h. in einer zeitlichen Auflösung zwischen ~30 und ~200 Jahren) untersucht. Darüber hinaus wurden Pollen und Sporen eines terrestrischen Kerns aus dem Drama-Becken (nördliches Hinterland der Ägäis) analysiert. Neben der qualitativen Analyse wurden mit Hilfe der Technik der modernen Analoge quantitative Rekonstruktionen der Paläotemperaturen und -niederschläge im terrestrischen Raum vorgenommen. Für den marinen Kern wurden außerdem Sedimenthelligkeit, Sauerstoffisotopie und magnetische Suszeptibilität untersucht. Über die Entwicklung eines konsistenten Altersmodells für beide Kerne konnten Aussagen über eine regionale, klimagesteuerte Differenzierung zwischen der Vegetationsentwicklung im Küstenbereich und der Vegetationsentwicklung in intramontanen Ökosystemen getroffen werden. Während des Pleniglazials (~21 ka bis ~14,7 ka BP) herrschten im nördlichen Ägäisraum kühle und vor allem trockene Bedingungen vor. Offen liegende Schelfflächen wurden von einer Pinus-dominierten Vegetation besiedelt, bis der Schelf während des anschließenden Meiendorf-Bølling-Allerød-Interstadialkomplexes (~14,7 ka bis ~12,7 ka BP) durch den Schmelzwasserpuls MWP-1A überflutet wurde. Während des Meiendorf-Bølling-Allerød-Interstadialkomplexes herrschten im nördlichen Ägäisraum etwas humidere Bedingungen als während des Pleniglazials. In der anschließenden Jüngeren Dryas (~12,7 ka bis ~11,7 ka BP) war das Klima hingegen mindestens ebenso arid und die Oberflächenwassertemperaturen in der Nordägäis fast ebenso gering wie während des Pleniglazials. Das lokale Klima im Drama Becken war von ~21 ka BP bis zum Ende der Jüngeren Dryas generell trockener als die allgemeinen Klimabedingungen im nördlichen Ägäisraum. Die Vegetationsentwicklung im nördlichen Ägäisraum wurde während des Spätquartärs vor allem durch die zur Verfügung stehende Feuchtigkeit gesteuert. Auch nach der Jüngeren Dryas war die Humidität im Ägäisraum zu gering, um eine Wiederbewaldung zu ermöglichen, wie sie in Mitteleuropa und dem westlichen Mittelmeergebiet bereits ab ~11,6 ka BP stattfand. Ein Vegetationsrückschlag um ~11,0 ka BP korreliert mit der aus Mitteleuropa bekannten präborealen Oszillation bzw. dem 11,2-ka-Klimaereignis. Die holozäne Wiederbewaldung setzte im östlichen Ägäisraum erst ab 10,2 ka BP ein; sie wurde durch einen sukzessiven Anstieg der Winterniederschläge von ~225 auf über ~300 mm/Jahr ermöglicht. Sowohl dieser Anstieg der Winterniederschläge als auch ihr Rückgang nach 7,0 ka BP sind eng mit der Ablagerung des Sapropels S1 (zwischen ~9,6 ka und ~7,0 ka BP) verknüpft. Die relativ humiden und milden Winterbedingungen während der Ablagerung des S1 wurden von durch Vegetationsrückschläge dokumentierten, kurzfristigen Klimaereignissen bei ~9,3 ka, ~8,7 ka, ~8,2 ka und ~7,6 ka BP unterbrochen. Diese kurzfristigen Klimaereignisse gehen mit Unterbrechungen bzw. Abschwächungen der S1-Bildung einher. Besonders ausgeprägt ist der regionale Ausdruck des 8,2-ka-Ereignisses, welches für die am stärksten ausgeprägte und auch aus anderen Bereichen des östlichen Mittelmeers überlieferte Unterbrechung des S1 zwischen ~8,4 ka und ~8,0 ka verantwortlich zeichnet. Während der Bildung des S1 wurde die Klimaentwicklung im Ägäisraum generell weniger vom Klimasystem der hohen Breiten beeinflusst als vielmehr vom Monsunsystem der niederen Breiten. Allerdings war die Intensität des Sibirischen Hochs während des frühen Holozäns und nach dem S1-Intervall ein wichtiger Faktor für das Winterklima. Auch während des Holozäns wurden Klimaschwankungen im Drama-Becken deutlicher von der lokalen Vegetation reflektiert als von der Vegetation des nördlichen Ägäisraums im Allgemeinen. So wirkte sich z.B. das 8,2-ka-Ereignis sehr stark auf die Vegetationsentwicklung im Drama Becken aus; es verursachte einen Rückgang der Sommer- und Wintertemperaturen um mehr als 3° C. Dieser starke Temperatureinbruch ist auf lokale mesoklimatische Effekte zurückzuführen. Die Vegetation in den Randbereichen der Ägäis erfuhr weitere Rückschläge bei ~6,5 ka, ~5,6 ka und ~4,3 ka BP. Die Einbrüche bei ~5,6 ka und ~4,3 ka BP sind mit rapiden Klimaänderungen in großen Teilen der Nordhemisphäre korrelierbar, die ebenso wie die Jüngere Dryas und das 8,2-ka-Klimaereignis Einfluss auf Hochkulturen in Nordostafrika und im Mittleren Osten hatten. Die aus dem Holozän überlieferten Klimadaten machen deutlich, dass dieser Zeitraum von einer weitaus stärkeren Klimavariabilität geprägt wurde als noch bis vor kurzem angenommen.To unravel the climate-driven dynamics of terrestrial and marine ecosystems in the Aegean region during the Lateglacial and Holocene, terrestrial (pollen and spores) and marine (organic-walled dinoflagellate cysts) palynomorphs from a marine core from the Mount Athos Basin (Northern Aegean Sea) were analyzed in a temporal resolution of ~200 to ~30 years. These analyses were complemented by sediment lightness, oxygen isotope and magnetic susceptibility measurements. Furthermore, pollen and spores from a terrestrial core from the Drama Basin (northern borderlands of the Aegean Sea) were examined. Quantitative temperature and precipitation reconstructions were carried out using the modern analogues technique. Based on the development of a consistent age model for both cores, a spatially differentiated reconstruction of the vegetation dynamics in coastal settings and in intramontane ecosystems could be achieved. During the Pleniglacial (~21 kyr to ~14.7 kyr BP), the Aegean region was under the influence of cool and dry conditions. Exposed shelf areas were colonized by a Pinus-dominated vegetation until their flooding (notably through meltwater pulse MWP-1A) in the course of the Meiendorf-Bølling-Allerød interstadial complex (~14.7 kyr to ~12.7 kyr BP). During the Meiendorf-Bølling-Allerød interstadial complex, climate conditions were more humid than during the Pleniglacial. A pronounced climatic setback is registered for terrestrial environments during the Younger Dryas (~12.7 kyr to ~11.7 kyr BP) when conditions were nearly as arid and cold as during the Pleniglacial. Surface-water temperatures in the northern Aegean Sea also decreased markedly during that time. The local climate in the Drama Basin was generally dryer than in the greater northern Aegean Region from ~21 kyr BP until the end of the Younger Dryas. Vegetation dynamics in the northern Aegean Region were more driven by the available humidity than by temperature. After the Younger Dryas, when the Holocene reforestation started in Central Europe, humidity in the Aegean region was still insufficient to support reforestation. Tree populations even declined around ~11.0 kyr BP; this vegetation setback correlates with, but is more strongly pronounced than the preboreal oscillation known from Central Europe. Holocene reforestation did not start before ~10.2 kyr BP when winter precipitation successively increased from ~225 to ~300 mm/year. This increase and also a winter precipitation decrease after ~7.0 kyr BP is closely related with the formation of Sapropel S1 in the Aegean Sea (between ~9.6 kyr und ~7.0 kyr BP). The relatively humid winter conditions during S1 formation were interrupted by short-term climate setbacks at ~9.3 kyr, ~8.7 kyr, ~8.2 kyr, and ~7.6 kyr BP, which are documented by declines in thermophilous tree pollen. These climate setbacks are coeval with a weakening or interruption of S1 formation. The regional imprint of the 8.2-kyr climatic event is particularly strongly pronounced. This event caused the strongest interruption of S1 formation from ~8.4 to ~8.0 kyr BP. During S1 formation, the climate dynamics in the Aegean Region were less strongly influenced by the climate systems of the higher latitudes, but also bear a signature of the monsoonal system of the lower latitudes. However, the intensity of the Siberian High was an important factor in controlling winter climate conditions in the northern Aegean Region during the Early Holocene and after the S1 interval. Climate dynamics were more clearly reflected by the vegetation of the Drama Basin than by the vegetation in the northern Aegean Region in general. The 8.2-kyr-climate-event e.g. had a major influence on the vegetation dynamics in the Drama Basin and caused a decline in winter and summer temperatures by more than 3° C. This can be explained by local mesoclimatic effects. The vegetation in the borderlands of the Aegean Sea experienced further setbacks around ~6.5 kyr, ~5.6 kyr and ~4.3 kyr BP. The setbacks around ~5.6 kyr and ~4.3 kyr BP can be correlated with climate setbacks known from other regions in the Mediterranean region, which had great influence on human cultures in north-eastern Africa and in the Middle East. The climate data from the Holocene show that the climate during this time interval was much more variable than previously presumed

Miocene honey bees from the Randeck Maar of southwestern Germany (Hymenoptera, Apidae)

This is the publisher's version, also available electronically from http://www.pensoft.net.The Miocene Randeck Maar (southwestern Germany) is one of the only sites with abundant material of fossil honey bees. The fauna has been the focus of much scrutiny by early authors who recognized multiple species or subspecies within the fauna. The history of work on the Randeck Maar is briefly reviewed and these fossils placed into context with other Tertiary and living species of the genus Apis Linnaeus (Apinae: Apini). Previously unrecorded specimens from Randeck Maar were compared with earlier series in an attempt to evaluate the observed variation. A morphometric analysis of forewing venation angles across representative Recent and Tertiary species of Apis as well as various non-Apini controls was undertaken to evaluate the distribution of variation in fossil honey bees. The resulting dendrogram shows considerable variation concerning the wing venation of Miocene Apini, but intergradation of other morphological characters reveals no clear pattern of separate species. This suggests that a single, highly variable species was present in Europe during the Miocene. The pattern also supports the notion that the multiple species and subspecies proposed by earlier authors for the Randeck Maar honey bee fauna are not valid, and all are accordingly recognized as Apis armbrusteri Zeuner

Terrestrial climate variability and seasonality changes in the Mediterranean region between 15 000 and 4000 years BP deduced from marine pollen records

Pollen-based climate reconstructions were performed on two high-resolution pollen marines cores from the Alboran and Aegean Seas in order to unravel the climatic variability in the coastal settings of the Mediterranean region between 15 000 and 4000 years BP (the Lateglacial, and early to mid-Holocene). The quantitative climate reconstructions for the Alboran and Aegean Sea records focus mainly on the reconstruction of the seasonality changes (temperatures and precipitation), a crucial parameter in the Mediterranean region. This study is based on a multi-method approach comprising 3 methods: the Modern Analogues Technique (MAT), the recent Non-Metric Multidimensional Scaling/Generalized Additive Model method (NMDS/GAM) and Partial Least Squares regression (PLS). The climate signal inferred from this comparative approach confirms that cold and dry conditions prevailed in the Mediterranean region during the Oldest and Younger Dryas periods, while temperate conditions prevailed during the Bølling/Allerød and the Holocene. Our records suggest a West/East gradient of decreasing precipitation across the Mediterranean region during the cooler Late-glacial and early Holocene periods, similar to present-day conditions. Winter precipitation was highest during warm intervals and lowest during cooling phases. Several short-lived cool intervals (i.e. Older Dryas, another oscillation after this one (GI-1c2), Gerzensee/Preboreal Oscillations, 8.2 ka event, Bond events) connected to the North Atlantic climate system are documented in the Alboran and Aegean Sea records indicating that the climate oscillations associated with the successive steps of the deglaciation in the North Atlantic area occurred in both the western and eastern Mediterranean regions. This observation confirms the presence of strong climatic linkages between the North Atlantic and Mediterranean regions

Middle to Late Holocene Variations in Salinity and Primary Productivity in the Central Baltic Sea: A Multiproxy Study From the Landsort Deep

Anthropogenic forcing has led to an increased extent of hypoxic bottom areas in the Baltic Sea during recent decades. The Baltic Sea ecosystem is naturally prone to the development of hypoxic conditions due to its geographical, hydrographical, geological, and climate features. Besides the current spreading of hypoxia, the Baltic Sea has experienced two extensive periods of hypoxic conditions during the Holocene, caused by changing climate conditions during the Holocene Thermal Maximum (HTM; 8–4.8 cal ka BP) and the Medieval Climate Anomaly (MCA; 1–0.7 cal ka BP). We studied the variations in surface and bottom water salinity and primary productivity and their relative importance for the development and termination of hypoxia by using microfossil and geochemical data from a sediment core retrieved from the Landsort Deep during IODP Expedition 347 (Site M0063). Our findings demonstrate that increased salinity was of major importance for the development of hypoxic conditions during the HTM. In contrast, we could not clearly relate the termination of this hypoxic period to salinity changes. The reconstructed high primary productivity associated with the hypoxic period during the MCA is not accompanied by considerable increases in salinity. Our proxies for salinity show a decreasing trend before, during and after the MCA. Therefore, we suggest that this period of hypoxia is primarily driven by increasing temperatures due to the warmer climate. These results highlight the importance of natural climate driven changes in salinity and primary productivity for the development of hypoxia during a warming climate

Arachnids in Bitterfeld amber: A unique fauna of fossils from the heart of Europe or simply old friends?

Bitterfeld amber, sometimes referred to as Saxon or Saxonian amber, is a potentially significant but poorly known source of arthropod data for the Palaeogene of northern Europe. An important aspect is a long-standing controversy about the age of this amber: namely whether it is equivalent to, and perhaps merely a southerly extension of, the better-known Baltic amber, or whether it is a unique and geological younger deposit sampling a different fauna. Here, we briefly review the Bitterfeld arachnids with particular emphasis on how these data could be used to elucidate the age of this deposit. Five arachnid orders have been recorded from Bitterfeld amber: spiders (Araneae), acariform mites (Acariformes), parasitiform mites (Parasitiformes), harvestmen (Opiliones) and pseudoscorpions (Pseudoscorpiones). This is a lower diversity than Baltic amber, where scorpions (Scorpiones) and camel spiders (Solifugae) have also been recorded. Spiders are the most comprehensively studied group, with more than 75 described species. Other groups such as pseudoscorpions and mites appear to be very diverse, but are virtually undescribed. Morphological overlap is apparent in the arachnid fauna and 40 species are currently shared between Baltic and Bitterfeld amber whilst 50 species are unique to the Bitterfeld deposit. At the family level overlap is even higher, but in all groups Baltic amber appears more diverse than Bitterfeld. This overlap may be interpreted as evidence for temporal conspecifity of the Baltic and Bitterfeld ambers, albeit with the Bitterfeld and Baltic ambers possibly representing independent localities within a larger Eocene European amber area which also included the Rovno amber from the Ukraine. However, caution should be exercised because the taxonomic foundation for such assumptions is far from comprehensive, most of the material remains to be studied in detail using modern techniques of morphological reconstruction. There are further issues with date estimates because some arachnid groups show extraordinary morphological stasis over time, even at species level, which may bias the analyses available. Here, we review the available knowledge on Bitterfeld arachnids and discuss how a detailed assessment of this fauna, and other arthropod taxa, could be generated. Several natural history museums – including Hamburg and Berlin – as well as private collectors host major assemblages of Bitterfeld fossils which may help to clarify the debate about the age and provenance of the material, and the extent to which (morpho)-species were maintained both over geographical distances and potentially geological time

Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model–data comparison

Climate evolution of the Mediterranean region during the Holocene exhibits strong spatial and temporal variability. The spatial differentiation and temporal variability, as evident from different climate proxy datasets, has remained notoriously difficult for models to reproduce. In light of this complexity, we examine the previously described evidence for (i) opposing northern and southern precipitation regimes during the Holocene across the Mediterranean basin, and (ii) an east-to-west precipitation gradient or dipole during the early Holocene, from a wet eastern Mediterranean to dry western Mediterranean. Using quantitative climate information from marine and terrestrial pollen archives, we focus on two key time intervals, the early to mid-Holocene (8000 to 6000 cal yrs BP) and the late Holocene (4000 to 2000 yrs BP), in order to test the above mentioned hypotheses on a Mediterranean-wide scale. Palynologically derived climate information is compared with the output of regional-scale climate-model simulations for the same time intervals. Quantitative pollen-based precipitation estimates were generated along a longitudinal gradient from the Alboran (West) to the Aegean Sea (East); they are derived from terrestrial pollen records from Greece, Italy and Malta as well as from pollen records obtained from marine cores. Because seasonality represents a key parameter in Mediterranean climates, special attention was given to the reconstruction of season-specific climate information, notably summer and winter precipitation. The reconstructed climatic trends corroborate a previously described north-south partition of precipitation regimes during the Holocene. During the early Holocene, relatively wet conditions occurred in the south-central and eastern Mediterranean region, while drier conditions prevailed from 45° N northwards. These patterns reversed during the late Holocene, with a wetter northern Mediterranean region and drier conditions in the east and south. More sites from the northern part of the Mediterranean basin are needed to further substantiate these observations. With regard to the existence of a west-east precipitation dipole during the Holocene, our pollen-based climate data show that the strength of this dipole is strongly linked to the seasonal parameter reconstructed: Early Holocene summers show a clear east-to-west gradient, with summer precipitation having been highest in the central and eastern Mediterranean and lowest over the western Mediterranean. In contrast, winter precipitation signals are less spatially coherent. A general drying trend occurred from the early to the late Holocene; particularly in the central and eastern Mediterranean. However, summer precipitation in the east remained above modern values, even during the late Holocene interval. Pollen-inferred precipitation estimates were compared to regional-scale climate modelling simulations based on the HadAM3 GCM coupled to the dynamic HadSM3 and the high-resolution regional HadRM3 models. Climate model outputs and pollen-inferred precipitation estimates show remarkably good overall correspondence, although many simulated patterns are of marginal statistical significance. Nevertheless, models weakly support an east to west division in summer precipitation and there are suggestions that the eastern Mediterranean experienced wetter summer and winter conditions during the early Holocene and wetter summer conditions during the late Holocene. The extent to which summer monsoonal precipitation may have existed in the southern and eastern Mediterranean during the mid-Holocene remains an outstanding question; our model, consistent with other global models, does not suggest an extension of the African monsoon into the Mediterranean. Given the difficulty in modelling future climate change in Southern Europe, more simulations based on high resolution global models and very high resolution regional downscaling, perhaps even including transient simulations, are required to fully understand the patterns of change in winter and summer circulation patterns over the Mediterranean regio

First record of the spider family Hersiliidae (Araneae) from the Mesozoic of Europe (Bakony Mts, Hungary)

An adult male Hersiliidae spider is described from amber that originates from the Upper Cretaceous (Santonian) Ajka Coal Formation (Ajka-Csingervölgy, Hungary), the so-called ajkaite. The spider has elongate posterior spinnerets and a short third pair of legs III, both characteristics of the family, but differs from all known Mesozoic (discovered in burmite) and fossil and Recent European representatives of Hersiliidae so that a new genus and species name is proposed for Hungarosilia verdesi gen. et sp. nov. The new taxon is distinguishable by the following unique combination of characters: pro- and opisthosoma nearly circular in dorsal view; posterior spinnerets with a distal article more than three times longer than the basal article; pedipalpal tibia and patella short and stout but pedipalpal femur as long as the cymbium, cymbium egg-shaped and without cymbial apophysis; bulbus of circular shape in ventral view and slightly flattened is lateral view. The fossil represents the first record of Hersiliidae from the Mesozoic of Europe and establishes the second record of this family in the Mesozoic Era. The estimated paleoclimate and paleoflora of the Ajka coal sub-basin correspond well with habitat preferences of Recent relatives that are often arborical and found in association with tree bark. Overall, our findings highlight the importance of a neglected amber type, the ajkaite, for documenting and studying the European arthropod fauna during the Mesozoic

The marine isotope stage 1–5 cryptotephra record of Tenaghi Philippon, Greece:Towards a detailed tephrostratigraphic framework for the Eastern Mediterranean region

The iconic climate archive of Tenaghi Philippon (TP), NE Greece, allows the study of short-term palaeoclimatic and environmental change throughout the past 1.3 Ma. To provide high-quality age control for detailed palaeoclimate reconstructions based on the TP archive, (crypto)tephra studies of a peat core ‘TP-2005’ have been carried out for the 0–130 ka interval. The results show that the TP basin is ideally positioned to receive tephra fall from both the Italian and Aegean Arc volcanic provinces. Two visible tephra layers, the Santorini Cape Riva/Y-2 (c. 22 ka) and the Campanian Ignimbrite (CI)/Y-5 (c. 39.8 ka) tephras, and six primary cryptotephra layers, namely the early Holocene E1 tephra from the Aeolian Islands (c. 8.3 ka), the Campanian Y-3 (c. 29 ka) and X-6 tephras (c. 109.5 ka), as well as counterpart tephras TM-18-1d (c. 40.4 ka), TM-23-11 (c. 92.4 ka) and TM-33-1a (c. 116.7 ka) from the Lago Grande di Monticchio sequence (southern Italy), were identified along with repeatedly redeposited Y-2 and CI tephra material. Bayesian modelling of the ages of seven of the primary tephra layers, 60 radiocarbon measurements and 20 palynological control points have been applied to markedly improve the chronology of the TP archive. This revised chronology constrains the age of tephra TM-18-1d to 40.90–41.66 cal ka BP (95.4% range). Several tephra layers identified in the TP record form important isochrons for correlating this archive with other terrestrial (e.g., Lago Grande di Monticchio, Sulmona Basin and Lake Ohrid) and marine (e.g., Adriatic Sea core PRAD 1-2 and Aegean Sea core LC21) palaeoclimate records in the Mediterranean region

Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding 'Fossils from conflict zones and reproducibility of fossil‑based scientific data': Myanmar amber

Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology. With our present, multi-authored comment, we aim to argue why these suggestions will not lead to improvement of both practice and ethics of palaeontological research but, conversely, hamper its further development. Although we disagree with most contents of the SVP letter, we appreciate this initiative to discuss scientific practices and the underlying ethics. Here, we consider different aspects of the suggestions by Rayfield et al. (2020) in which we see weaknesses and dangers. It is our intent to compile views from many different fields of palaeontology, as our discipline is (and should remain) pluralistic. This contribution deals with the aspects concerning Myanmar amber. Reference is made to Haug et al. (2020a) for another comment on aspects concerning amateur palaeontologists/citizen scientists/private collectors