Quantifying the effect of anthropogenic climate change on calcifying plankton

Widely regarded as an imminent threat to our oceans, ocean acidification has been documented in all oceanic basins. Projected changes in seawater chemistry will have catastrophic biotic effects due to ocean acidification hindering biogenic carbonate production, which will in turn lead to substantial changes in marine ecosystems. However, previous attempts to quantify the effect of acidification on planktonic calcifying organisms has relied on laboratory based studies with substantial methodological limitations. This has been overcome by comparing historic plankton tows from the seminal HMS Challenger Expedition (1872-1876) with the recent Tara Oceans expedition material (2009-2016). Nano CT-scans of selected equatorial Pacific Ocean planktonic foraminifera, have revealed that all modern specimens had up to 76% thinner shells than their historic counterparts. The "Challenger Revisited" project highlights the potential of historic ocean collections as a tool to investigate ocean acidification since the early Industrial Revolution. Further analyses of such biotic archives will enable researchers to quantify the effects of anthropogenic climate change across the globe

The unknown planktonic foraminiferal pioneer Henry A. Buckley and his collection at The Natural History Museum, London

© 2017 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/). The version attached is the published pdf

Refining palaeoenvironmental analysis using integrated quantitative granulometry and palynology

Accurate palaeoenvironmental analysis is at the heart of producing reliable interpretations and depositional models. This study demonstrates a multivariate statistical approach to facies analysis based on relationships between grain size and quantitative palynology. Our methodology has the advantage that it can be used on small amounts of sample, such as core or well cuttings, as the basis for facies analysis. Proof of concept studies involving the collection of grain-size and palynological datasets from well-exposed outcrops of the Middle Jurassic, Lajas Formation of the Neuquén Basin, Argentina, demonstrate that canonical correspondence analysis can be used to consistently recognize facies and aid in the determination of depositional environments. This study demonstrates the link between depositional facies, grain-size distribution, palynomorph hydrodynamics and assemblage taphonomy of palynomorphs. This knowledge can be transferred into a semi-automated statistical facies prediction technique for the subsurface in complex depositional settings, particularly when calibrated against conventional sedimentary facies analysis.The attached article is the accepted manuscript for this article. You are advised to consult the publisher's version if you wish to cite from the article

Factors affecting consistency and accuracy in identifying modern macroperforate planktonic foraminifera

Planktonic foraminifera are widely used in biostratigraphic, palaeoceanographic and evolutionary studies, but the strength of many study conclusions could be weakened if taxonomic identifications are not reproducible by different workers. In this study, to assess the relative importance of a range of possible reasons for among-worker disagreement in identification, 100 specimens of 26 species of macroperforate planktonic foraminifera were selected from a core-top site in the subtropical Pacific Ocean. Twenty-three scientists at different career stages – including some with only a few days experience of planktonic foraminifera – were asked to identify each specimen to species level, and to indicate their confidence in each identification. The participants were provided with a species list and had access to additional reference materials. We use generalised linear mixed-effects models to test the relevance of three sets of factors in identification accuracy: participant-level characteristics (including experience), species-level characteristics (including a participant’s knowledge of the species) and specimen-level characteristics (size, confidence in identification). The 19 less experienced scientists achieve a median accuracy of 57 %, which rises to 75 % for specimens they are confident in. For the 4 most experienced participants, overall accuracy is 79 %, rising to 93 % when they are confident. To obtain maximum comparability and ease of analysis, everyone used a standard microscope with only 35× magnification, and each specimen was studied in isolation. Consequently, these data provide a lower limit for an estimate of consistency. Importantly, participants could largely predict whether their identifications were correct or incorrect: their own assessments of specimen-level confidence and of their previous knowledge of species concepts were the strongest predictors of accuracy

Episodic river flooding events revealed by palynological assemblages in Jurassic deposits of the Brent Group, North Sea

Spore and pollen (sporomorph) assemblages from Middle Jurassic marine deposits of the Brent Group in the northern North Sea are investigated to assess temporal and spatial variations in vegetation and depositional processes. Four wells were sampled for palynology from the Penguins Cluster and the Don North East fields through the Rannoch Formation shoreface succession. Hyperpycnite deposits occur throughout, but are concentrated within the lower part of the section. These are expressed by sand-prone beds displaying waxing and waning current motifs, normally graded muddy beds and structureless mudstones. Hyperpycnal/hypopycnal deposits resulting from episodic river flooding represent important sedimentary features as they may be preserved below fair weather wave base in more offshore settings and potentially be the only record of the former presence of a nearby river mouth. The hyperpycnites typically contain abundant Botryoccocus spp., Amorphous Organic Matter (AOM) and hinterland sporomorph taxa with relatively few marine components compared to associated marine shoreface facies. Variations in palynofacies assemblages and Botryococcus spp. abundances indicate frequent river mouth avulsion. Ordination of samples using non-metric multidimensional scaling (NMDS) indicates that shoreface samples of the sampled wells are relatively distinct, but hyperpycnite samples are highly similar regardless of their sampled well. This suggests that depositional processes and spore/pollen sources (i.e. catchment zones) were similar among hyperpycnite events across different wells. Abundant bisaccate pollen, Botryococcus spp. and AOM within interpreted hyperpycnites suggest sediment mixing along the fluvial drainage path during flooding events. The terrestrial signature of hyperpycnite sporomorph assemblages demonstrates that underflows remained coherent as they descended the shoreface profile with little turbulent mixing with ambient marine waters. Sporomorph assemblages display few large changes through time suggesting vegetation on the adjacent coastal plain was relatively static through the studied interval

Early Cretaceous vegetation and climate change at high latitude: Palynological evidence from Isachsen Formation, Arctic Canada

Quantitative palynology of the marginal marine and deltaic-fluvial Isachsen Formation of the Sverdrup Basin, Canadian Arctic, provides insight into high latitude climate during much of the Early Cretaceous (Valanginian to early Aptian). Detrended Correspondence Analysis of main pollen and spore taxa is used to derive three ecological groupings influenced by moisture and disturbance based on the botanical affinities of palynomorphs: 1) a mixed coniferous assemblage containing both lowland and upland components; 2) a conifer-filicopsid community that likely grew in dynamic lowland habitats; and, 3) a mature dry lowland community composed of Cheirolepidiaceans. Stratigraphic changes in the relative abundance of pollen and spore taxa reflect climate variability in this polar region during the ~20 Mya history of the Isachsen Formation. The late Valanginian was relatively cool and moist and promoted lowland conifer-filicopsid communities. Warming in the Hauterivian resulted in the expansion coniferous communities in well-drained or arid hinterlands. A return to relatively cool and moist conditions in the Barremian resulted in the expansion of mixed lowland communities. This work demonstrates the utility of a multivariate statistical approach to palynology to provide insight into the composition and dynamics of ecosystems and climate of high latitude regions during the Early Cretaceous

Spatial and temporal palynological trends in marginal marine depositional system : Lajas Formation, Neuquén Basin, Argentina

In order to better understand the relationship of tidally dominated depositional environments and their palynological assemblages, the Middle Jurassic sediments of the Lajas Formation, Neuquén Basin were examined. The ambition was to present models and trends which can be used for studies of other such deposits. In order to integrate the palynoassemblages with the environment of deposition, additional granulometric data and nutrient data from XRF analysis were used in combination with the palynology. A new method using correspondence analysis was used for understanding the palaeoecology and floral dynamics. An updated, dynamic model for the Middle Jurassic floral palaeoecology of the Neuquén Basin has been presented and the drivers of floral succession are interpreted as disturbance tolerance and substrate water content. Taphonomic expressions of seral groupings show that later seral stage community palynomorphs are preferentially deposited within or close to distributary systems, whereas earlier seral stage palynomorphs are preferentially deposited in environments of greater accommodation space, such as bayfills. Taphonomic signatures, using palaeoecological groupings provide trends in low (4th/5th) order cycles and lateral variations relating to tidal channels and surrounding bayfill mudstones. A model for 4th/5th order boundaries is also presented using new interpretations of the distribution of pinaceous pollen and microforaminiferal test linings. Using Canonical Correspondence Ananlysis (CCA), a model is presented of depositional environments incorporating palynological data and granulometric proxies for grain size and grain sorting. The relationship between sediment processes in a tidal flat dominated palaeoenvironment and the hydrodynamic properties of some palynomorphs is investigated and presented. The weathering and nutrient status of the substrates throughout the Lajas Formation is presented using XRF proxy data. The proxies are also used with CCA to create nutrient related floral groupings. When plotted stratigraphically, these show cycles of eutrophication and subsequent weathering of the substrates.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

New species of Mesozoic benthic foraminifera from the former British Petroleum micropalaeontology collection

© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. The attached file is the published version of the article

Fluvial to tidal transition in proximal, mixed tide-influenced and wave-influenced deltaic deposits: Cretaceous lower Sego Sandstone, Utah, USA

Facies models for regressive, tide-influenced deltaic systems are under-represented in the literature compared with their fluvial-dominated and wave-dominated counterparts. Here, a facies model is presented of the mixed, tide-influenced and wave-influenced deltaic strata of the Sego Sandstone, which was deposited in the Western Interior Seaway of North America during the Late Cretaceous. Previous work on the Sego Sandstone has focused on the medial to distal parts of the outcrop belt where tides and waves interact. This study focuses on the proximal outcrop belt, in which fluvial and tidal processes interact. Five facies associations are recognized. Bioturbated mudstones (Facies Association 1) were deposited in an offshore environment and are gradationally overlain by hummocky cross-stratified sandstones (Facies Association 2) deposited in a wave-dominated lower shoreface environment. These facies associations are erosionally overlain by tide-dominated cross-bedded sandstones (Facies Association 4) interbedded with ripple cross-laminated heterolithic sandstones (Facies Association 3) and channelized mudstones (Facies Association 5). Palaeocurrent directions derived from cross-bedding indicate bidirectional currents which are flood-dominated in the lower part of the studied interval and become increasingly ebb-directed/fluvial-directed upward. At the top of the succession, ebb-dominated/fluvial-dominated, high relief, narrow channel forms are present, which are interpreted as distributary channels. When distributary channels are abandoned they effectively become estuaries with landward sediment transport and fining trends. These estuaries have sandstones of Facies Association 4 at their mouth and fine landward through heterolithic sandstones of Facies Association 3 to channelized mudstones of Facies Association 5. Therefore, the complex distribution of relatively mud-rich and sand-rich deposits in the tide-dominated part of the lower Sego Sandstone is attributed to the avulsion history of active fluvial distributaries, in response to a subtly expressed allogenic change in sediment supply and relative sea-level controls and autocyclic delta lobe abandonment

Comment on: Galasso, F., Feist-Burkhardt, S. and Schneebeli-Hermann, E. 2022. “The palynology of the Toarcian Oceanic Anoxic Event at Dormettingen, southwest Germany, with emphasis on changes in vegetational dynamics”. Review of Palaeobotany and Palynology, 304, 104701

In a recently-published paper, Galasso et al. (2022) interpreted relatively high levels of unseparated spore tetrads and some darkened miospores which occur immediately below the Toarcian Oceanic Anoxic Event (~ 183 Ma) in southwest Germany as resulting from enhanced levels of UV-B radiation due to high levels of volcanism at this time. The present authors consider that this teratological interpretation is unlikely, and more plausible explanations of these phenomena are rapid sedimentation and short transport durations, and reworking respectively