Summary1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date, there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on time-scales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human-environment interactions in the Anthropocene; biodiversity, conservation and novel ecosystems; biodiversity over long time-scales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes and the continued application of long-term data for better-informed landscape management. 256-26750 priority research questions in palaeoecology 257 7. Synthesis. Palaeoecology is a vibrant and thriving discipline, and these 50 priority questions highlight its potential for addressing both pure (e.g. ecological and evolutionary, methodological) and applied (e.g. environmental and conservation) issues related to ecological science and global change.

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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Plagiogrammaceae, a poorly described family of diatoms, are common inhabitants of the shallow marine littoral zone, occurring either in the sediments or as epiphytes. Previous molecular phylogenies of the Plagiogrammaceae were inferred but included only up to six genera: Plagiogramma, Dimeregramma, Neofragilaria, Talaroneis, Psammogramma and Psammoneis. In this paper, we describe a new plagiogrammoid genus, Orizaformis, obtained from Bohai Sea (China) and present molecular phylogenies of the family based on three and four genes (nuclear-encoded large and small subunit ribosomal RNAs and chloroplast-encoded rbcL and psbC). Also included in the new phylogenies is Glyphodesmis. The phylogenies suggest that the Plagiogrammaceae is composed of two major clades: one consisting of Talaroneis, Orizaformis and Psammoneis, and the second of Glyphodesmis, Psammogramma, Neofragilaria, Dimeregramma and Plagiogramma. In addition, we describe three new species within established genera: Psammoneis obaidii, which was collected from the Red Sea, Saudi Arabia; and Neofragilaria stilus and Talaroneis biacutifrons from the Mozambique Channel, Indian Ocean, and illustrate two new combination taxa: Neofragilaria anomala and Neofragilaria lineata. Our observations suggest that the biodiversity of the family is strongly needed to be researched, and the phylogenetic analyses provide a useful framework for future studies of Plagiogrammaceae.

Regime shifts are often used to describe sharp changes between two or more ecological states, each characterized by their own dynamics, stochastic fluctuations, or cycles. Ecological theory indicates they can occur either as a result of an abrupt environmental forcing (extrinsic regime shift), or be indicative of complex responses to local-scale dynamics and thresholds (intrinsic regime shift). One important area of ecological research is to develop quantitative tools to analyze regime shifts, but there are few studies that have applied these methods to the long-term ecological record. In this study, we introduce a framework to investigate regime shifts in diatom assemblages and mangrove ecosystem dynamics in a coastal lagoon from the Gala´pagos Islands over the past 2600 years. The framework integrates a set of established statistical methodologies for investigating regime shift dynamics in long-term ecological records. We use these methods to (1) identify the presence of regime shifts; (2) test for a series of hypothetical relationships (i.e., linear through to threshold) between ecological response and environment using nonlinear regression; and (3) investigate the relative importance of intrinsic and extrinsic dynamics in response to environmental perturbations. The transitions in the diatoms closely track the sequence of disturbance, recovery, and habitat shifts that have occurred in the lagoon over the past 2600 years, demonstrating extrinsic responses to environmental forcing. In contrast, the shift from a mangrove-to a microbial mat-dominated system ;945 cal yr BP provides potential evidence of an intrinsic regime shift. Our framework enables robust interpretations into the underlying dynamics of regime shifts in the paleoecological record and is widely applicable for investigating abrupt ecological changes in a range of systems.

Sound knowledge of present-day diatom species and their environments is crucial when attempting to reconstruct past climate and environmental changes based on fossil assemblages. For the North Atlantic region, the biogeography and ecology of many diatom taxa that are used as indicator-species in paleoceanographic studies are still not well known. Using information contained in large diatomenvironment calibration datasets can greatly increase our knowledge on diatom taxa and improve the accuracy of paleoenvironmental reconstructions. A diatom calibration dataset including 183 surface sediment samples from the northern North Atlantic was used to explore the distribution and ecology of 21 common Northern Hemisphere diatom taxa. We define the ecological responses of these species to April sea ice concentrations and August sea surface temperatures (aSSTs) using Huisman-Olff-Fresco (HOF)-response curves, provide distribution maps, temperature optima and ranges, and high-quality light microscope images. Based on the results, we find species clearly associated with cold, warm and temperate waters. All species have a statistically significant relationship with aSST, and 15 species with sea ice. Of these, Actinocyclus curvatulus, Fragilariopsis oceanica and Porosira glacialis are most abundant at high sea ice concentrations, whereas Coscinodiscus radiatus, Shionodiscus oestrupii, Thalassionema nitzschioides, Thalassiosira angulata, Thalassiosira nordenskioeldii and Thalassiosira pacifica are associated with low sea ice concentrations/icefree conditions. Interestingly, some species frequently used as sea ice indicators, such as Fragilariopsis cylindrus, show similar abundances at high and low sea ice concentrations with no statistically significant relationship to sea ice.present the geographical distribution of the common diatom species in the northern North Atlantic, (2) discuss the relationship between diatom species and two important environmental variables (SST and sea ice) and (3) present good-quality light-microscopy images of these species to aid with species identification. Materials and methodsA diatom calibration dataset (Andersen et al., 2004a(Andersen et al., , 2004bMiettinen et al., 2015) including 183 surface sediment samples (prepared for analysis using standard methodology, see Koç Karpuz and Schrader, 1990;Koç et al., 1993) and measured environmental data (SSTs and sea ice concentrations) around the North Atlantic, the Labrador Sea, the Nordic Seas and Baffin Bay (Fig. 1) was used in this study to examine the biogeography and ecology of common North Atlantic diatom taxa. The calibration dataset consists of 52 diatom species in total, of which we selected the 21 most common species based on their wide-ranging occurrence at high latitudes and their frequent use as paleoceanographic indicators in the northern North Atlantic and Arctic regions. However, some common North Atlantic taxa, such as Chaetoceros resting spores, Paralia sulcata, Fossula arctica and Fragilariopsis reginae-jahniae were not included in ...

1997 (September): The Baltic Ice Lake in the southwestern Baltic: sequence-, chrono-and biostratigraphy. fkJrcWS, Vol. 26, pp,[217][218][219][220][221][222][223][224][225][226][227][228][229][230][231][232][233][234][235][236] This multidisciplinary study focuses on late-glacial deposits in the Mecklenburg Bay -Arkona Basin area. The sequence stratigraphical method has been used on shallow seismic and lithological data, in combination with biostratigraphical work and radiocarbon dating. Glacial-till deposits underlie sediments from two Baltic Ice Lake phases. Varved clay deposits from the initial phase cover the deepest parts of the basins. A prograding delta is observed at the western margin of the Arkona Basin, prograding from the Darss Sill area. The delta system is possibly related to a highstand dated at 12.8 ka. A maximum transgression level around 20 m below present sea level (b.s.1.) is inferred, followed by a drop in water level and formation of lowstand features. The final ice lake phase is characterized by a new transgression. The transgression maximum as observed in the Mecklenburg Bay is represented by transgressive and highstand deltaic deposits. These also indicate a maximum shore level of 20 m b.s.1. The deltaic scdiments that contain macroscopic plant remains and diatoms have yielded Younger Dryas ages. Mapping of the late-glacial morphology of the Darss Sill area reveals a threshold at 23 to 24 ni b.s.1. This means that the Baltic Ice Lake highstand phases inundated the Darss Sill, which implies that the westernmost extension of the Baltic Ice Lake reached as far as Kiel Bay. Forced regressive coastal deposits at the western margin of the Arkona Basin mark a lowstarid level of around 40 m b.s.1. caused by the final drainage of the Baltic Ice Lake. The lowstand deposits predate lacustrine deposits from the Ancylus Lake, which date to approximately 9.6 ka BP.