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The species Mulinia lateralis (Say, 1822) is native in the western North Atlantic Ocean and was first documented in European coastal waters in 2017. Since then, M. lateralis was reported several times in large abundances in the coastal waters of the Netherlands, Belgium and Germany. While the introduction vector is still unclear we assume that further dispersal in the southern North Sea will be driven by larval drift related to anti-clockwise residual tidal currents. To report its current distribution status in the central Wadden Sea, individuals were collected systematically from intertidal flats along 10 transects ranging from the outer Ems River estuary to the outer Elbe River estuary (German North Sea coast) between February and May 2022. In total, 897 specimens of M. lateralis were sampled from 392 stations (mean abundance 2.29 ± 4.97 ind./m²). The shell length ranged between 3.98 and 23.55 mm thus representing at minimum two cohorts. Regarding the increasing number of records of M. lateralis at multiple sites in Europe since 2017, the species can be considered as established in the western and central Wadden Sea.

In light of global warming and rising relative sea level (RSL), detailed reconstructions of RSL histories and their controlling processes are essential in order to manage coastal‐protection challenges. This study contributes to unravelling Holocene RSL change on the East Frisian North Sea coast in high resolution and with a new approach for the German Bight. For the first time, a transfer function (vertical error: 29.7 cm ≙ ~11% of the mean tidal range) for RSL change based on a combined training set of benthic foraminifers and ostracods from the back‐barrier tidal basin of Spiekeroog is applied to the Holocene record of the back‐barrier tidal basin of Norderney. The resulting RSL curve for the Norderney tidal basin is corrected for decompaction and shows a deceleration in RSL rise between 6000 and 5000 cal bp. The smallest possible error envelope (~1 m) results from the good suitability of salt‐marsh layers between 5000 and 4000 cal bp. The RSL curve provides an approach towards the closure of the common data gap of peat‐based curves for the southern North Sea related to a lack of basal peats in the youngest age range, and verifies regional differences in glacial isostatic adjustment., Volkswagen Foundation http://dx.doi.org/10.13039/501100001663, Niedersächsisches Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/501100010570

Pteridinium simplex is an iconic erniettomorph taxon best known from late Ediacaran successions in South Australia, Russia, and Namibia. Despite nearly 100 years of study, there remain fundamental questions surrounding the paleobiology and paleoecology of this organism, including its life position relative to the sediment–water interface, and how it fed and functioned within benthic communities. Here, we combine a redescription of specimens housed at the Senckenberg Forschungsinstitut und Naturmuseum Frankfurt with field observations of fossiliferous surfaces, to constrain the life habit of Pteridinium and gain insights into the character of benthic ecosystems shortly before the beginning of the Cambrian. We present paleontological and sedimentological evidence suggesting that Pteridinium was semi-infaunal and lived gregariously in aggregated communities, preferentially adopting an orientation with the long axis perpendicular to the prevailing current direction. Using computational fluid dynamics simulations, we demonstrate that this life habit could plausibly have led to suspended food particles settling within the organism's central cavity. This supports interpretation of Pteridinium as a macroscopic suspension feeder that functioned similarly to the coeval erniettomorph Ernietta, emblematic of a broader paleoecological shift toward benthic suspension-feeding strategies over the course of the latest Ediacaran. Finally, we discuss how this new reconstruction of Pteridinium provides information concerning its potential relationships with extant animal groups and state a case for reconstructing Pteridinium as a colonial metazoan.

The reconstruction of submerged palaeolandscapes and detection of settling surfaces along coastal zones became a major research topic within the last two decades. In this context, the WASA project made use of a multidisciplinary approach for defining the extension and describing the characteristics of the Late Pleistocene to Holocene deposits in the central Wadden Sea region. In addition to sub-bottom transects, more than 140 sediment cores were taken in such an area for stratigraphic reconstruction, making use of multi-proxy analysis. To harmonize these data with the existing regional core database (LBEG archive) a new core catalogue was developed, that allows the identification of the local Late Quaternary sedimentary sequences and their characteristic facies. The WASA core catalogue has been successfully applied for reviewing the published data about the stratigraphic sequence of the Wadden Sea, for a better definition in terms of stratigraphic sequences and spatial extent of the Quaternary geological evolution of the region, and for a detailed reconstruction of the coastal palaeoenvironments.

Before proxy records can be reliably employed in palaeoclimate research, calibration studies have to be conducted to assess the confidence intervals of the respective proxies. Here, we use shells of the fast growing Pacific oyster Magallana gigas from the Central Wadden Sea, North Sea, a temperate barrier island-backbarrier tidal flat-salt marsh system with large seasonal changes of water mass-properties, for the calibration of geochemical proxies. M. gigas represents a non-native invasive species that rapidly develops oyster reefs. Calcite shells of two specimens from the intertidal and subtidal zones were sampled in high resolution yielding sub-monthly data sets. The time period represented in the shell, based on δ18O age modelling, was estimated at 8-10 years and the growth of the shells was restricted from (late) spring to (early) autumn of each year. Mg/Ca, Mn/Ca and Sr/Ca ratios of the intertidal and subtidal specimens show similar seasonal patterns. Mg/Ca and Sr/Ca ratios are investigated as high-resolution sea surface temperature (SST) proxies. Important ontogenetic effects (i.e., increasing time-averaging with increasing age) as well as intra-species variability are discussed as limiting factors for the proxy development. Intertidal Mg/Ca ratios show only a significant correlation to the high-resolution SST record of the Central Wadden Sea when the early ontogenetic stage is considered. Sr/Ca ratios were comparable in terms of absolute values and amplitudes to those of M. gigas in the Northern Wadden Sea, but amplitudes were decreasing with increasing ontogeny. These findings seriously hamper the application of Mg/Ca and Sr/Ca for reliable palaeotemperature reconstructions regardless of ontogenetic stage. The Mn/Ca ratios were investigated as proxy for Mn cycling in tidal basins, where it is interrelated with seasonal changes in primary production. In addition to the generally observed seasonal variability of the Mn/Ca records, the subtidal Mn/Ca is significantly elevated compared to intertidal Mn/Ca. The subtidal Mn/Ca offset likely reflects differences in Mn cycling in tidal settings and could, therefore, serve in the palaeorecord as indicator to differentiate inter- and subtidal habitats in the same embedding sedimentary facies. This habitat effect has to be considered as an important factor besides environmental change when interpreting the high-resolution proxy record of fossil oysters.

Netherlands journal of geosciences : NJG 100, e4 (2021). doi:10.1017/njg.2020.16, Published by Cambridge Univ. Press, Cambridge

Accelerator mass spectrometry (AMS) radiocarbon (14C) dating ofCerastoderma edule(Linnaeus 1767) andMytilus edulis(Linnaeus 1758) shells sampled in AD 1889 near the island of Wangerooge gave a new local correction factor ΔR of −85 ± 1714C years for the Wadden Sea area. The value is considerably higher than the available scattered data from the North Sea, which were obtained from pre-bomb growth rings of livingArctica islandica(Linnaeus 1767). This can be explained by the incorporation of14C-depleted terrestrial carbon into the shell material which compensates the intensified exchange of CO2between atmosphere and shallow coastal water, e.g. by tidal currents. Additionally, two examples of application of the new ΔRvalue in coastal research give deeper insights into the dynamics of bivalve shell preservation in the Wadden Sea and the need for further research to clarify the Holocene reintroduction ofMya arenaria(Linnaeus 1758) into European waters.

The Holocene sea-level rise has led to significant changes in present-day coastal zones through multifold retrogradational and slightly progradational displacements of the mainland coastline. During the course of this postglacial transgression, sediments characteristic of coastal environments accumulated first in palaeovalleys of the pre-Holocene landscape and later on the subsequently developed coastal plain. Based on a compilation of sedimentological, lithological and litho-chronostratigraphical data of more than 1200 sediment cores, we generated four palaeogeographic maps of the coastal zone of the central Wadden Sea to document with a high spatial resolution the landscape changes during characteristic phases of the Holocene sea-level rise, i.e. the periods 8600–6500 cal BP, 6500–2700 cal BP, 2700–1500 cal BP and 1500–1000 cal BP. Along three cross-sections, representing different hydrodynamic conditions and exposure, we exemplify how the Holocene landscape development and sedimentary facies types are controlled by the local palaeorelief, sea-level changes, sediment supply, accommodation space, the morphodynamic impact of channel shifts, and their erosion base. This leads to a better understanding of main factors controlling the local depositional processes of the coastal landscape along the central Wadden Sea during the Holocene transgression.

Pleistocene strata of the Wadden Sea region are mostly covered by an up to 10m thick sediment wedge deposited during the Holocene transgression. However, tidal inlets cut deep into the Holocene succession, causing Middle Pleistocene to early Holocene glacial and interglacial deposits to outcrop at the channel bottom. To investigate how the lithological properties and/or morphologies of these deposits affect the development of Holocene tidal inlets (e.g. limiting erosional processes), we analysed a series of eight cores to verify three high-resolution sub-bottom transects – and thus – to extend point-based data over a broader area. Furthermore, eight additional new cores (16 WASA cores in total), and 14 reinterpreted cores from the LBEG (Geological Survey of Lower Saxony) log database, were correlated to generate three short cross-sections at the transition from the tidal inlet (Riffgat channel) to the island of Norderney, revealing a number of new aspects for the reconstruction of the Pleistocene palaeoenvironments, i.e. the last two glacials (Saalian and Weichselian) and interglacials (Holsteinian? and Eemian). A succession of Middle Pleistocene lacustrine delta deposits, belonging either to the Holsteinian or the Dömnitz temperate stage, suggests the presence of Elsterian tunnel valleys located below the island. Furthermore, we verified the presence of an Eemian mixed tidal-flat system overlain by an Eemian sand tidal flat below the western head of Norderney which is, in contrast to suggestions from previous studies, not fully eroded in this area. Finally, we demonstrate that the Saalian moraine (Drenthe Main Till) functions as a limiting constraint in the vertical development of the Holocene/modern Riffgat channel. Our results provide a better understanding of the Quaternary stratigraphy of the central Wadden Sea as well as the influence of the subsurface geology on the architecture and evolution of tidal channels.

Non-metamorphic Palaeozoic sedimentary successions without major breaks exist in the Istanbul Zone of the Western Pontides (northern Turkey) and in the Taurides (southern Turkey). Based on different proxies, a Gondwanan affinity has been determined for the Taurides; however, the palaeogeographical position of the Istanbul Zone is still controversial. The aim of this paper is to discuss possible contributions of late Silurian and Devonian ostracods to the palaeogeographical assignment of the Western Pontides (Istanbul Zone). Furthermore, ostracods of the Taurides have also been evaluated in terms of the palaeogeographical setting of this terrane. Late Silurian ostracods of the Istanbul Zone (Western Pontides) show close similarities at the species level with the assemblage from the upper Silurian (Ludlow) rocks of Baltica. This Laurussian affinity indicates a palaeogeographical setting to the north of the Rheic Ocean for the Pontides during the late Silurian. The Devonian ostracod assemblages of both the Taurides and the Istanbul Zone have an affinity to both Laurussia and Gondwana. Therefore, a faunal link should exist during this long period between Laurussia and Gondwana. The faunal link between the two palaeocontinents can be explained on the one hand by a narrow ocean with shallow pathways. On the other hand, a wider ocean with long-shore currents, with broad and shallow shelf areas and/or islands functioning as stepping stones would also allow a faunal link for benthic ostracods. © 2018, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag GmbH Germany, part of Springer Nature. Firat University Scientific Research Projects Management Unit TUR04/009, 01DL12036 111Y179 104Y218 Funding information This study was supported by TÜBİTAK/Turkey (DEVEC-TR, Project No. 104Y218, and DECENT, Project No.111Y179), the International Bureau of the BMBF/Germany (Project Nos. TUR04/009 and 01DL12036) and the Çukurova University Scientific Research Projects Coordination Unit (Project Nos. MMF2009YL56 and MMF2012BAP4).

The Wadden Sea is a highly productive coastal ecosystem and an important nursery ground for various demersal fishes of the southern North Sea. Copepods are one of the major food sources of the ecosystem, yet little is known about the movement patterns of this benthic meiofaunal group within both sediment and water column in the intertidal environment, where they would be more vulnerable for predation. The diversity and abundance of harpacticoids emerging and recolonizing intertidal sand flats were investigated during two diurnal and two nocturnal high tides, using specifically designed traps. Our study revealed no significant difference in the amount of copepods emerging from the sediment into the water column during the day and the night. Furthermore, the proportion of emerging adults and copepodids did not differ from each other and most individuals persisted in the sediment during high tide. Interestingly, the most abundant species Arenosetella tenuissima and Tachidius discipes showed an opposite emergence behavior, with the former migrating in higher numbers during the night and the latter during the day. Although tidal inundation was the proximate factor initiating emergence, we suggest that sediment reworking by tidal currents, waves and bioturbation as well as water and food availability above and within the sediment may be additional factors controlling emergence of harpacticoids in the Wadden Sea, with light intensity playing a minor role. Therefore, emergence and recolonization patterns of harpacticoids from subtidal ecosystems cannot directly be transferred to intertidal areas as the time for benthic pelagic processes is limited to high tides.

Marine environments are threatened by biological invaders that are transported via ship hulls or ballast water at increasing rates around the globe. Most management strategies that should prevent or reduce the impact of alien species include prevention and eradication programs that both rely on an early detection of introduced species. Early detection requires an up to date inventory of present species and efficient monitoring programs to identify newly arrived species. This study surveyed potential invasion ‘hot spots’ in the coastal waters of the central Wadden Sea, including commercial ports (‘port’ stations) as well as fairways, roads, groynes and oyster reefs (‘Wadden Sea’ stations) to establish lists of macrobenthic species as baseline for future monitoring. In the ports we applied simultaneously the HELCOM/OSPAR protocol (H/O) and a regional established rapid assessment (RA) to enable the evaluation of the effectiveness and comprehensiveness of both methods. While the RA is mainly based on the visual screening of species in easy accessible habitats in the field, the H/O includes an extensive sampling by operation of scientific divers boat times and a 4-times higher time effort for sample processing. We identified among all sites 273 species including 37 alien species. The fauna was composed of 210 native and 32 alien species, while the flora was composed of 26 native and 5 alien species. The ports were a diverse habitat with species numbers from 65 to 109. At the Wadden Sea stations, exclusively monitored by the less extensive RA, only half of the species numbers (36–66 species) were detected. However, on the oyster reefs the relative occurrence of alien species compared to natives was similar to the ports and one oyster reef (Nordland) even had the highest ratio (25%, 14 species) of alien species of all investigated sites. The H/O protocol identified 179 species compared to 114 species identified by the RA. Regarding alien species, the H/O provided 85% of alien species, the RA only 67%. Especially with regard to the actual discussion on harmonized monitoring protocols within the Northeast Atlantic and Baltic regions, we recommend that future port surveys should apply the more extensive H/O protocol, since restrictions to the RA decrease drastically the chance of an early detection of alien species. We also recommend complementing the survey of ports with natural invasion ‘hot spots’ like the oyster reefs by rapid assessment. This combined monitoring design secures a significant increase in the early detection of alien species as demonstrated in our study.

The ecosystem-based management (EBM) philosophy draws upon the principle that holistic understanding of the system to be governed needs to guide the decision-making process. However, empirical evidence is growing that knowledge integration is still a main bottleneck for EBM decision-makers. This paper argues that transdisciplinary knowledge management (TKM) is a key competence in achieving knowledge integration, while simultaneously it represents an underdeveloped research area in EBM if understood as a process of human interaction. Based on a literature review, this article summarizes and reflects upon the most recent development in the field of TKM. The paper presents a detailed definition and in-depth description of TKM as a process of human interaction and a diversity of organizational structures that effectuate TKM. Theoretically discussed premises are furthermore illuminated and evaluated by a case study that exemplifies pro-active development and implementation of TKM. Deviating case observations are presented as novel contributions to the field. They suggest new ideas and inspiration for future EBM research and policy agendas.

The behaviour of the iconic ichnogenus Chondrites is re-evaluated based on review of existing literature and analysis of novel data (macroscopic, thin section and ESEM-EDX observations; CT-scans and resin peels of modern analogues; computer-controlled serial grinding; morphometric analysis and theoretical morphology). The bedding plane expression of Chondrites is well-constrained by morphometry: (1) the angle of dichotomy formed by a pair of adjacent branches is typically between 30° and 56° (interquartile range; mean: 47°); (2) branching order is between 1 and 9; (3) branches are, on average, nine times longer than wide. In the third dimension, downward branching is dominant but bundled shafts and upward branching may be present. The size of Chondrites increased markedly from the Late Jurassic to the Late Cretaceous, suggesting that the tracemakers became larger and larger. Microfabric analysis of Chondrites shows active fill or, alternatively, passive fill of empty tunnels by currents or clay percolation, a new mechanism proposed herein. The tracemakers built Chondrites to obtain food: (1) vermiform deposit feeders produced Chondrites for searching for food in the sediment (fodinichnion); (2) asymbiotic bivalves built Chondrites for cultivating and directly ingesting bacteria (agrichnion); (3) chemosymbiotic bivalves produced Chondrites to provide symbionts with chemical agents. Chondrites was modified through the life of the tracemaker or it represented a part of the producer’s lifespan. Chondrites — and its modern tracemaker(s) — is associated with a range of marine settings, including well-oxygenated, dysoxic and space-limited (nucleocave) environments. As such, Chondrites is regarded as an extremotolerant ichnotaxon.

High-resolution proxy records are needed to evaluate models simulating past, present and future climatic conditions. Before such records can be reliably employed, calibration studies have to be conducted to assess the confidence intervals of the proxies. Here, we use shells of the fast growing Pacific oyster Magallana gigas from the Central Wadden Sea, North Sea, a temperate barrier island-backbarrier tidal flat-salt marsh system with large seasonal changes of water mass-properties, for the calibration of geochemical proxies. M. gigas represents a non-native invasive species that rapidly develops oyster reefs. Calcite shells of two specimens from the intertidal and subtidal zones were sampled in high resolution yielding sub-monthly data sets. The time period represented in the shell, based on δ18O age modeling, was estimated at 8–10 years and the growth of the shells was restricted from (late) spring to (early) autumn of each year. Mg/Ca, Mn/Ca and Sr/Ca ratios of the intertidal and subtidal specimens show similar seasonal patterns. Mg/Ca and Sr/Ca ratios are investigated as high-resolution sea surface temperature (SST) proxies. Important ontogenetic effects (i.e., increasing time-averaging with increasing age) as well as inter-specimen variability are discussed as limiting factors for the proxy development. Intertidal Mg/Ca ratios show only a significant correlation to the high-resolution SST record of the Central Wadden Sea when the early ontogenetic stage is considered. Sr/Ca ratios were comparable in terms of absolute values and amplitudes to those of M. gigas in the Northern Wadden Sea, but amplitudes were decreasing with increasing age. These findings seriously hamper the application of Mg/Ca and Sr/Ca for reliable palaeotemperature reconstructions regardless of ontogenetic stage. The Mn/Ca ratios were investigated as proxy for Mn cycling in tidal basins, where it is interrelated with seasonal changes in primary production. In addition to the generally observed seasonal variability of the Mn/Ca oyster records, the subtidal Mn/Ca is significantly elevated compared to intertidal Mn/Ca. The subtidal Mn/Ca offset likely reflects differences in Mn cycling in tidal settings and could, therefore, serve in the palaeorecord as indicator to differentiate inter- and subtidal habitats in the same embedding sedimentary facies. This habitat effect has to be considered as an important factor besides environmental change when interpreting the high-resolution proxy record of fossil oysters.

This study addresses key processes in high-energy beach systems using an interdisciplinary approach. We assess spatial variations in subsurface pore water residence times, salinity, organic matter (OM) availability, and redox conditions and their effects on nutrient cycles as well as on microbial community patterns and microphytobenthos growth. At the study site on Spiekeroog Island, southern North Sea, beach hydrology is characterized by the classical zonation with an upper saline plume (USP), a saltwater wedge, and a freshwater discharge tube in between. Sediment and pore water samples were taken along a cross-shore transect from the dunes to the low water line reaching sediment depths down to 5 m below sediment surface. Spatial variations in pore water residence time, salinity, and organic matter availability lead to steep redox and nutrient gradients. Vertical and horizontal differences in the microbial community indicate the influence of these gradients and salinity on the community structure. Modeled seawater flux through the USP and freshwater flux through the tube are on average 2.8 and 0.75 m3 per day and meter of shoreline, respectively. Furthermore, ridge sediments at the lower beach discharge seawater at rates of 0.5 and 1.0 m3 per day and meter of shoreline towards the runnel and seaside, respectively. Applying seawater and freshwater fluxes and representative nutrient concentrations for the discharge zones, nutrient fluxes to adjacent nearshore waters are 117 mmol NH4+, 55 mmol PO43 − and 575 mmol Si(OH)4 per day and meter of shoreline. We propose that this nutrient efflux triggers growth of microphytobenthos on sediment surfaces of the discharge zone. A first comparison of nutrient discharge rates of the beach site with a nearby sandy backbarrier tidal flat margin indicates that the beach system might be of less importance in supplying recycled nutrients to nearshore waters than the backbarrier tidal flat area.

Pinnoputamen erikfluegeli and Sycidium aff. volborthi magnum from Akkuyu (Southern Taurides) are the first Palaeozoic charophytes reported from Turkey, and their presence emphasises the world-wide distribution of Sycidiales during the Middle and Upper Devonian. Both species occur in the upper part of the Akkuyu Section of late Givetian through early Frasnian age, based on combined biostratigraphical data. The sedimentary sequence mainly consists of reefal limestones and silt-/sandstones, partly intercalated with shales. In these nearshore deposits, charophytes and open marine fossils, notably brachiopods and conodonts, are found associated. With reference to identical primordial structures of vegetative and reproductive organs both in extant and Palaeozoic forms, and account taken of the prerequisite environmental conditions (such as salinity, light intensity, and nature of substratum), the mode of life in Palaeozoic charophytes was certainly similar to that of modern ones. By a critical review of other fossil occurrences interpreted as marine, we conclude that an allochthonous origin is most probable for the charophytes of the Akkuyu Section. © 2018, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag GmbH Germany, part of Springer Nature. DECENT 01DL12036 Drexel University: 499 The following colleagues are thanked for age assignments by results of fossil groups for which they are specialists: Rainer Brocke (palynomorphs), Ulrich Jansen (brachiopods), Karsten Weddige (conodonts), all Senckenberg Frankfurt; Recep ?zkan (foraminifers), TPAO Ankara; and Helga Groos-Uffenorde (some comments on ostracods), G?ttingen. The Turkish-German research team is acknowledged for joint fieldwork in 2012 (Nihat Bozdo?an, Rainer Brocke, Ulrich Jansen, Ulf Linnemann, Recep ?zkan, ?sak Y?lmaz). Michael Ricker, Jana Anger (both Senckenberg Frankfurt) and Torsten Janssen (Senckenberg am Meer Wilhelmshaven) are thanked for preparation of thin sections, assistance in photography, and conducting XRD samples, respectively. This study contributes to the project ?Sedimentary cycles and signatures of global events in the Devonian at the Northern margin of Gondwana, Southern Turkey (DECENT)?, supported by T?B?TAK (project DECENT 111Y179) and the International Bureau of the BMBF (project DECENT 01DL12036). We are grateful to Hans Martin Weber (Bergisch-Gladbach) for loan of specimens from the Refrath Formation. We acknowledge Brigitte Meyer-Berthaud (CIRAD Montpellier) for assistance in transmission microscopy and Chantal Cazevieille for her support in SEM. Thanks are also due to Richard Mc Court (Drexel University, Philadelphia) who linguistically improved parts of an early version of the manuscript. The reviewers Carlton Brett (Cincinatti) and Grzegorz Racki (Sosnowiec) are acknowledged for their helpful comments. This is a contribution to IGCP Project 499 ?Devonian Land-Sea Interactions: Evolution of Ecosystems and Climate (DEVEC)?. Contribution ISEM 20188-278.

Conventional continental geoarchives are rarely available in arid southern Africa. Therefore, palaeoclimate data in this area are still patchy and late Quaternary climate development is only poorly understood. In the western Kalahari, salt pans (playas, ephemeral lakes) are common and can feature quasi-continuous sedimentation. This study presents the first climate-related biomarker record using sediments from the Omongwa Pan, a Kalahari salt pan located in eastern Namibia. Our approach to reconstruct vegetation and hydrology focuses on biogeochemical bulk parameters and plant wax-derived lipid biomarkers (n-alkanes, n-alkanols, and fatty acids) and their compound-specific carbon and hydrogen isotopic compositions. The presented record reaches back to 27 ka. During the glacial, rather low δ2H values of n-alkanes and low sediment input exclude a strong influence of winter rainfall. n-Alkane and n-alkanol distributions and δ13C values of n-hentriacontane (n-C31) indicate a shift to a vegetation with a higher proportion of C4 plants at the end of the Last Glacial Maximum until the end of Heinrich Stadial I (ca. 18–14.8 ka), which we interpret to indicate an abrupt excursion to a short wetter period likely to be caused by a temporary southward shift of the Intertropical Convergence Zone. Shifts in δ2H values of n-C31 and plant wax parameters give evidence for changes to drier conditions during early Holocene. Comparison of this dataset with representative continental records from the region points to a major influence of summer rainfall at Omongwa Pan during the regarded time span and demonstrates the potential of southern African salt pans as archives for biomarker-based climate proxies.

In the course of a biomonitoring program to compile a neobiota baseline for German North Sea coastal waters of the Federal State of Lower Saxony, different natural and artificial hard substrates and various soft substrates were sampled at potential bioinvasion ‘hot-spots’ in the region. The survey followed the standardized sampling guideline of the HELCOM/OSPAR protocol. We identified several colonies of Smittoidea prolifica Osburn, 1952 at two harbours in the Jade estuary. Both harbours are characterized by international shipping activity while the Jade Weser Port was only recently constructed between 2009 and 2012. However, the vector of introduction remains unclear. These records from November 2014 are the first for German coastal waters.

In order to evaluate the importance of coastal sandy sediments and their contribution to carbon, nutrient and metal cycling we investigated two beach sites on Spiekeroog Island, southern North Sea, Germany, and a tidal flat margin, located in Spiekeroog's backbarrier area. We also analyzed seawater and fresh groundwater on Spiekeroog Island, to better define endmember concentrations, which influence our study sites. Intertidal sandy flats and beaches are characterized by pore water advection. Seawater enters the sediment during flood and pore water drains out during ebb and at low tide. This pore water circulation leads to continuous supply of fresh organic substrate to the sediments. Remineralization products of microbial degradation processes, i.e. nutrients, and dissolved trace metals from the reduction of particulate metal oxides, are enriched in the pore water compared to open seawater concentrations. The spatial distribution of dissolved organic carbon (DOC), nutrients (PO43−, NO3−, NO2−, NH4+, Si(OH)4 and total alkalinity), trace metals (dissolved Fe and Mn) as well as sulfate suggests that the exposed beach sites are subject to relatively fast pore water advection, which leads to organic matter and oxygen replenishment. Frequent pore water exchange further leads to comparatively low nutrient concentrations. Sulfate reduction does not appear to play a major role during organic matter degradation. High nitrate concentrations indicate that redox conditions are oxic within the duneward freshwater influenced section, while ammonification, denitrification, manganese and iron reduction seem to prevail in the ammonium-dominated seawater circulation zone. In contrast, the sheltered tidal flat margin site exhibits a different sedimentology (coarser beach sands versus finer tidal flat sands) and nutrients, dissolved manganese and DOC accumulate in the pore water. Ammonium is the dominant pore water nitrogen species and intense sulfate reduction leads to the formation of sulfide, which precipitates dissolved iron as iron sulfide. These findings are due to slower advective pore water exchange in the tidal flat sediments. This study illustrates how different energy regimes affect biogeochemical cycling in intertidal permeable sediments.

Since 1994, Hemigrapsus penicillatus, an Asian brush-clawed shore crab, spreads along Northeast Atlantic coasts. There is evidence that the most recently described and widely accepted sibling species of H. penicillatus, namely Hemigrapsus takanoi, represents the Asian brush-clawed brachyuran crab in Europe. Morphological characteristics are considered insufficient for species discrimination, and molecular analyses were recommended but have to date not been performed in Europe. To clarify the identity of the non-indigenous Asian brush-clawed crab species, which has been invading intertidal alien Crassostrea reefs in the Wadden Sea, we analysed more than 3.5 kpb of mitochondrial and nuclear genes of individuals from invaded German sites and from native Japanese sites. In addition to molecular analyses, we also document key morphological and morphometric characteristics of the same individuals to provide a comparative description. While morphological identification was not confidently feasible, our molecular results confirm the existence of Hemigrapsus takanoi as a closely related species to H. penicillatus and have identified H. takanoi to be the alien brush-clawed crab species in Germany. Furthermore, most of the analysed specimens from Japan and all additional NCBI-listed brush-clawed crabs from Japan, Korea and China which were traditionally classified as H. penicillatus in Asia, are de facto H. takanoi.

Non-indigenous Pacific oysters ( Crassostrea gigas ) have been invading the central Wadden Sea since 1998, predominantly settling on intertidal blue mussel ( Mytilus edulis ) beds which are increasingly transformed into Crassostrea -reefs. Pacific oysters are strong ecosystem engineers and the habitat change is considered to be a threat for waterbirds losing important feeding sites in the intertidal of the Wadden Sea. This study has increased our understanding of the use of foraging habitats by birds according to changing food resources. During the spring and autumn migration period in 2007, we recorded bird densities at two reef types varying in Pacific oyster density and at the adjacent sand flat as a reference site. We also recorded feeding behaviour, choice of prey and assessed peck and intake rate of three target species: Eurasian oystercatcher Haematopus ostralegus , Eurasian curlew Numenius arquata and European herring gull Larus argentatus . To evaluate the use of the Crassostrea -reef in the central Wadden Sea, we compared bird densities of the target species at different intertidal feeding habitats in various regions and compared the biomass intake of Eurasian oystercatcher feeding on different prey species. We show that Eurasian oystercatcher and Eurasian curlew have adapted to the new situation and learned to exploit the food supply offered by Crassostrea -reefs. While foraging mainly on Pacific oysters, Eurasian oystercatchers attained sustainable intake rates even though food resource at dense reef during autumn was very poor due to a lack in harvestable oysters. Consolidation of reefs limits the accessibility of prey for Eurasian oystercatchers whereas a successful recruitment of Pacific oysters enhances the suitability of the habitat. Eurasian curlew was promoted by the engineering effects of the Pacific oyster while feeding extensively on shore crabs at the reefs. In contrast, European herring gulls appear hampered in foraging during low tide and hereby negatively affected by the habitat change from Mytilus -beds to Crassostrea -reefs.

On the southern flanks of the Tindouf Basin (Western Sahara) reefal complexes of various sizes were developed, mostly of Givetian age but possibly reaching into the early Frasnian. Surrounding sedimentary rocks were dominantly sandstones, siltstones and marls. The larger reef complexes in the northeastern part of Western Sahara show three reef cycles within the Givetian and lowermost Frasnian, interrupted by marly sedimentation. Farther to the west, more isolated reef structures in open shelf settings occur often showing smaller dimensions. The present study focuses on one of these western reefal build-ups. Besides large-scale reefs dominated by stromatoporoids (NE), several smaller bioherms have been investigated, such as the Gwirat Al Hyssan reef-mound near Smara. Initial reef growth was of late Givetian age as indicated by corals (e.g. Heliolites ). The main reef builders were the corals Alveolites , Thamnopora , Aulopora , Frechastraea , Phillipsastrea , and, to a lesser degree, Heliolites, Scoliopora, and Roemerolites . Stromatoporoids also contributed, but were less frequent. Chaetetids (e.g. Rhaphidopora ) acted as pioneer stabilizers on bare sediment surfaces. Preservation in life position was frequently observed in both groups of organisms. Crinoids are not rare, but only present as debris. In distinct areas of the reef (depressions) concentrations of brachiopods and small solitary corals occur. The reef-mound has a present elevation of 17 m and measures about 370 m in diameter. Vertical as well as horizontal zonation could be recognized in detail. The initial reef growth started on a submarine shoal of siliciclastic sediments, containing various trace fossils and sedimentary structures such as cross-bedding and wave ripples; interference ripples suggest generation in very shallow water. The initial reef-building organisms were encrusting chaetetids, followed by platy Frechastraea colonies; thamnoporids were also present. The overlying reef limestones consist of different corals and, to a minor degree, stromatoporoids. The latter are sparsely distributed vertically as well as horizontally, depending on their position within the reef. Growth forms are more robust (bulbous) towards higher hydrodynamic conditions at the southern reef front. Reef growth is interrupted by debris limestones of thamnoporid and crinoid bioclasts, intercalated with detrital platy stromatoporoids. Generally, the debris was not transported over long distances, as demonstrated by the presence of relatively large fragments. This ‘debris phase’ (early Frasnian) is overlain by the last documented stage in reef development represented by medium- to thin-bedded coral-rich limestones. The onset of the carbonate production of the Gwirat Al Hyssan reef-mound is maybe related to the global transgressive Givetian–Frasnian Boundary Event.

There is a mistake in the caption of Fig. 8m. It should be “Svantovites lethiersi Casier, 1979” instead of “Svantovites lethiersi Becker 1971”.

Since 1998 the non-indigenous Pacific oyster Crassostrea gigas (Thunberg 1793) has been invading the Wadden Sea of Lower Saxony, southern German Bight. C. gigas settles predominantly on intertidal Mytilus-beds (M. edulis L.) and subsequently create rigid reef-like structures. Both bivalve species are ecosystem engineers in sedimentary tidal flats. They provide hard substrate for sessile species, mobile organisms find refuge within the habitat matrix of dense suspension feeders, and biodeposits enrich the sediments with organic matter. The transformation of Mytilus-beds into Crassostrea-reefs gives rise to the question whether the invader may affect the native community. We investigated two parts of a changing bivalve bed in the backbarrier area of the island of Juist in March 2005. One part was still dominated by M. edulis whereas the other part was already densely colonized by C. gigas. Crassostrea-reefs compensate for the conceivable loss of Mytilus-beds in the intertidal of the Wadden Sea by replacing the ecological function of M. edulis. There was no indication of a suppression of indigenous species. This even applied to M. edulis, which persisted at the site invaded by C. gigas. The associated macrofaunal community showed increased species richness, abundance, biomass, and diversity in the Crassostrea-reef. The latter particularly favored sessile species like anthozoans, hydrozoans, and barnacles. Higher abundance and biomass for vagile epizoic species like the shore crab Carcinus maenas and the periwinkle Littorina littorea also occurred among oysters. Abundance of deposit feeding oligochaetes was enhanced by oysters as well. More opportunistic, facultative filter-feeding polychaetes occurred in the Crassostrea-reef.

Phototrophic biofilms of the Kachelotplate were studied to assess their role in sediment stabilization. At most sampling stations the surficial sediment was dominated by diatoms with occasional cyanobacterial unicells and filaments interspersed. Coherent mats of filamentous cyanobacteria were found in protected parts of the upper intertidal zone, while the central dune field and foreshore sediments were only rarely colonized. Photosynthetic activity was indicated by iron hydroxide coatings of sand grains below the biofilms. Temporal changes in the distributional record of biofilm phototrophs suggested disturbances by aeolian processes and strong hydrodynamic events. Heavy storm surges and floods erode the central dune field, and also transported sediments towards East into the more sheltered tidal flat area. This results in changing of topographic reliefs, filling-up of sheltered depressions formerly good for mat development and altering of surface habitats for biofilm growth. Aeolian transport of sediment into the biofilm-stabilized tidal flats occurs more or less permanently throughout the year. The sedimentological importance of surface biofilms is demonstrated by their capability to intervene with erosion and sedimentation processes by trapping and binding sediment particles, and by the production of organic matter which gradually alters internal biogeochemistry. After burial, mat-derived strata represent obstacles to interstitial hydrology and fluxes of elements-enriched porewater. Considering the dynamically exposed transitional state of the Kachelotplate from an ephemeral sand bank island to part of a barrier island, the dynamic shifts of habitats favorable for biofilm growth should carefully be monitored.

The Kachelotplate is an ephemeral sand bank island which frequently appeared and disappeared since the first recorded in nautical charts of the 17th century. Within the stability field of barrier islands it represents the sole occurrence of an ephemeral sand body showing formation of initial aeolian dunes with vegetation cover. Due to its exposed position the Kachelotplate complex is strongly affected by high hydrodynamic impact of storm surges occurring several times a year. This results in sedimentary dynamics preventing the development of a stable, storm-resistant dune belt which would be necessary for the evolution of a barrier island. Nevertheless, most of the sedimentary/structural units of the Kachelotplate are known as typical elements of the adjacent barrier islands. These findings suggest that this ephemeral sand bank island may reflect the ‘missing link’ in the well-establishedBarckhausen model of barrier island evolution.

Since the late 1990s, the Pacific oyster (Crassostrea gigas) has spread into the East Frisian Wadden Sea (Germany). This invasion provided an opportunity to study the population dynamics and the patterns of spread during the initial bioinvasion process. With its source area in The Netherlands, the bioinvasion continues in an eastward direction, as documented by a gradient of high abundances in the west and low abundances in the east during the first study year. One year later, abundances of the Pacific oyster were more heterogenic and differed between adjacent tidal basins. The increase in population sizes at all study sites was very high, reaching levels similar to native occurrence populations. The growth constant (K) varied between 0.300 and 0.990 year−1. The mussel bed with the highest densities had a mean abundance of >300 ind. m−2, and a maximum of 1,460 ind. m−2. Furthermore, the bioinvasion was facilitated by a low mortality (Z) found for populations between 0.5 and 1.5 years old (Z = 0.03–0.13 year−1). At present, Pacific oysters are well established at several locations in the East Frisian Wadden Sea and may become with these reproductive potential self-sustaining populations.

The present interdisciplinary study comprising actuopalaeontology, marine biology and marine chemistry reveals particular polychaete species as trace-makers of distinct branched burrow systems in modern intertidal and shallow subtidal deposits. In this way, the study concerns one of the most enigmatic trace fossils in earth history, the cosmopolitan ichnogenus Chondrites. Bioturbate structures of this type are frequently found and described in the fossil record, as well as in deep sea cores from modern environments. So far, they have generally been ascribed to unknown producers living as endobenthic, chemosymbiontic organisms in anoxic sediments, mostly in deep sea environments. Scoloplos armiger, occurring in the German Wadden Sea in the lower parts of tidal flats, produces burrow structures that conform with numerous trace fossils of the ichnogenus Chondrites. Heteromastus filiformis, typical of the upper parts of tidal flats, produces burrows resembling trace fossils of the extended Chondrites group, namely the ichnogenus Pilichnus. Burrows of this trace fossil type were also found in subtidal muddy sediments near a barrier island at the coast of Georgia, U.S.A., originating from Capitella cf. aciculata. Pathways for detection of the modern traces, chemical properties of the sediments, life modes of the respective organisms and their environmental implications are briefly discussed. The results contribute to a more precise and differentiated interpretation of palaeoecologic and palaeooceanographic data.

The grey top-shell, Gibbula cineraria is a common member of temperate to cold water kelp forest communities, but its longevity and the age structure of its populations remains unresolved. Combined measurements of shell growth rates (sclerochronology) and oxygen isotope composition allow analysis of rate and timing of shell growth. Eight specimens were analyzed from the southern North Sea (near Helgoland, German Bight). Three age groups were identified but external measurements (width, height, ornamentation patterns and number of whorls) and shell weight are not adequate for ontogenetic age discrimination. Stable oxygen isotope data is consistent with shell growth during the interval from April to December in isotopic equilibrium with seawater, and growth increments exhibit strong tidal controls with fortnightly bundles well preserved. Reliable environmental proxy data (water temperature) can be extracted from the shell aragonite using conventional stable oxygen isotope analyses, with a temporal resolution of days attainable during intervals of maximum growth, but annual extremes are not always recorded in the shell. While demonstrating the utility of G. cineraria as a environmental and potential paleoenvironmental proxy for kelp forest habitats, its longevity has been significantly overestimated.

Trace fossiles and their ichnofabric are conventionally used in palaeontology to reconstruct the environmental parameters of sedimentary sequences. Specific trace fossils were taken as indicators for distinct trophic and bathymetric interpretations. Studies in modern environments have shown that the pathways of palaeoecological recognition are more complex than such linear and mechanistic approaches.

The occurrence of iron-rich concretions in intertidal areas of the Lower Saxonian Wadden Sea is described. These are found on top of sediments, mostly after erosion of formerMya arenaria beds. They usually contain an iron core around which layers of reduced and oxidised authigenic iron-rich minerals are arranged more or less concentrically. For the most part, these cores are composed of intact ammunition shells or fragments thereof, clearly relating the origin of these concretions to dumping activities after the second World War. Possible modes of formation of such concretions are discussed.

From spring 1997 to winter 2000, the composition and structure of epibenthic bivalve clusters and patches on a backbarrier tidal flat of the East Frisian Wadden Sea were continoously analyzed. The studied bivalve aggregates developed from intense and approximately simultaneous spatfalls of Mytilus edulis and Cerastoderma edule in 1996, after a severe winter (1995/96) with 64 days of driftice coverage. Spatfall occurred on a bare sandy tidal flat, whereas adjacent shell layers situated at the southern margin of the spatfall site were not colonized. Usually, such shell layers are the most common secondary hard substrates in the backbarrier area favorable for initial settlement of Mytilus larvae. The shell layers predominantly originate from erosion of former Mya arenaria and C. edule populations. So far, the studied bivalve aggregates are composed of approximately equal proportions of living specimens of both species, M. edulis and C. edule. The incorporated cockles were prevented from burrowing into the rediment by the coherent byssal mesh. In contrast to the results of previous studies, the great bulk of epibenthic living C. edule did survive for several years within the clusters. Therefore, the common terms ‘Mytilus banks’, ‘Mytilus patches’ or ‘Mytilus clumps’ may be too general and may erroneously imply a dominance of (or mono-specific composition by) M. edulis. In the fossil record, i.e. in diagenetically consolidated shell layers, the enforced epibenthic life-mode of C. edule and the remarkable species composition as well as the temporal development of the aggregates would not be recognizable.

Since the 1960s Pacific oysters(Crassostrea gigas) were imported to the North Sea coasts for aquaculture. The species was introduced to replenish the stock of the indigenous European oysterOstrea edulis which was strongly diminished in the past by overexploitation, diseases and severe winters. The introduction of this non-native species was regarded as uncritical due to the low water temperatures of the North Sea which would not have promoted natural reproduction and settlement. Nevertheless, strong spatfall of culturedC. gigas was recorded in several years in the Oosterschelde estuary (The Netherlands). From these spatfalls wild populations developed in the vicinity of the culture plots. Since the early 1980s Pacific oysters were also observed in the Wadden Sea area near Texel. The pelagic oyster larvae can bridge the distance between the Oosterschelde estuary and Texel by drifting with the residual currents which, at westerly winds, may transport them about 4 to 5 NM per day. Extreme spatfalls from culture plots were also recorded in the backbarrier tidal flats of the North Frisian Islands Sylt and Romo in 1991, 1994 and 1998. Settlement occurred predominantly on intertidalMytilus beds. The extended wild populations resisted two severe winters which were characterized by a drift-ice coverage lasting several weeks. In the backbarrier tidal flats of the East Frisian Islands the first specimens ofC. gigas were found in August 1998 onMytilus beds. In contrast to the wild oyster populations from the Oosterschelde and Sylt, the settlement ofC. gigas in the study area occurred far away from culture plots. In the following years, further records indicate a continued introduction of oyster larvae. This implies that the distribution gap ofC. gigas along the Wadden Sea coast is now closed.