Reconciling diverse lacustrine and terrestrial system response to penultimate deglacial warming in southern Europe

Unlike the most recent deglaciation, the regional expression of climate changes during the penultimate deglaciation remains understudied, even though it led into a period of excess warmth with estimates of global average temperature 1–2 °C, and sea level ∼6 m, above pre-industrial values. We present the first complete high-resolution southern European diatom record capturing the penultimate glacial-interglacial transition, from Lake Ioannina (northwest Greece). It forms part of a suite of proxies selected to assess the character and phase relationships of terrestrial and aquatic ecosystem response to rapid climate warming, and to resolve apparent conflicts in proxy evidence for regional paleohydrology. The diatom data suggest a complex penultimate deglaciation driven primarily by multiple oscillations in lake level, and provide firm evidence for the regional influence of abrupt changes in North Atlantic conditions. There is diachroneity in lake and terrestrial ecosystem response to warming at the onset of the last interglacial, with an abrupt increase in lake level occurring ∼2.7 k.y. prior to sustained forest expansion with peak precipitation. We identify the potentially important role of direct input of snow melt and glacial meltwater transfer to the subterranean karst system in response to warming, which would cause rising regional groundwater levels. This explanation, and the greater sensitivity of diatoms to subtle changes in temperature, reconciles the divergent lacustrine and terrestrial proxy evidence and highlights the sensitivity of lakes situated in mountainous karstic environments to past climate warming

On the origins of Cyprideis torosa (Jones, 1850) and a short biography of Professor T.R. Jones

The original description and taxonomic attribution of Cyprideis torosa (Jones, 1850) is reviewed with reference to the type locality at Grays, Essex, SE England and several of the original specimens are re-illustrated. A short biography of its author, the geologist T.R. Jones, is provided

Comparison of Sporormiella dung fungal spores and oribatid mites as indicators of large herbivore presence: evidence from the Cuzco region of Peru

The ability of sedimentary proxies (especially dung fungal spores) to reflect the past presence and density of large herbivores on a landscape has been receiving increasing scrutiny. Here we examine the Sporormiella spore record from a well-dated, multi-proxy, highly organic sedimentary record from the small lake basin of Marcacocha in the Cuzco region of Peru. The basin, a wetland since ca. AD 1840, existed as a small lake for at least 4000 years prior. Previous work at Marcacocha has shown that changes in herbivore densities reflect the abundances of oribatid mites preserved in the lake sediments. This study tests the assumption that both the Sporormiella and the oribatid mite records responded in broadly the same way to changes in herbivore densities over the past 1200 years. Analysis reveals a very low covariance between concentrations of Sporormiella spores and the two major components of the oribatid mite assemblage: a single aquatic species of Hydrozetes and a less abundant, wider grouping comprising members of the mostly terrestrial superfamily Ceratozetoidea (referred to as the ‘ceratozetoids’). Variations in the Hydrozetes assemblage clearly dovetail with known historical events, including the massive decline of indigenous and camelid populations following the collapse of the Inca Empire in the mid-sixteenth century. Comparison with other environmental proxies from the Marcacocha sequence, including diatoms and charophyte oospores, suggests that the ceratozetoids appear to reflect increasing terrestrialization. In contrast, although the Sporormiella record indicates the presence of livestock, it fails to register the major historical changes in herbivore presence, though reflects well episodes of lake-level lowering. In small lake settings, therefore, the use of Sporormiella to estimate the density of herbivores in the catchment might be considered a relatively blunt instrument when compared with some other indicators

The effect of optical substrates on micro-FTIR analysis of single mammalian cells

The study of individual cells with infrared (IR) microspectroscopy often requires living cells to be cultured directly onto a suitable substrate. The surface effect of the specific substrates on the cell growth—viability and associated biochemistry—as well as on the IR analysis—spectral interference and optical artifacts—is all too often ignored. Using the IR beamline, MIRIAM (Diamond Light Source, UK), we show the importance of the substrate used for IR absorption spectroscopy by analyzing two different cell lines cultured on a range of seven optical substrates in both transmission and reflection modes. First, cell viability measurements are made to determine the preferable substrates for normal cell growth. Successively, synchrotron radiation IR microspectroscopy is performed on the two cell lines to determine any genuine biochemically induced changes or optical effect in the spectra due to the different substrates. Multivariate analysis of spectral data is applied on each cell line to visualize the spectral changes. The results confirm the advantage of transmission measurements over reflection due to the absence of a strong optical standing wave artifact which amplifies the absorbance spectrum in the high wavenumber regions with respect to low wavenumbers in the mid-IR range. The transmission spectra reveal interference from a more subtle but significant optical artifact related to the reflection losses of the different substrate materials. This means that, for comparative studies of cell biochemistry by IR microspectroscopy, it is crucial that all samples are measured on the same substrate type. [Figure: see text

The biostratigraphy, palaeoecology and geochemistry of a long lacustrine sequence from NW Greece

Examination of an important new 319m core of lake sediment recovered from Ioannina in NW Greece has attempted to relate changes in the lake to variations in the regional climate of south-central Europe over the last 600,000 years. The site is known to have been extremely sensitive to past climatic change for three reasons: (i) temperate vegetation persisted throughout glacial stages (albeit at low frequencies), so the vegetational response to climatic change would therefore have been almost immediate; (ii) the extreme thickness of the sediments suggests that accumulation rates were high (at times, > 1m per thousand years), which has enabled high-resolution palaeoclimatic reconstructions; and (iii) precipitation of authigenic carbonate has preserved a remarkably sensitive proxy record of productivity variations for most of the lake's history. Well-defined shifts from glacial - interglacial mode have been correlated with vegetational changes identified in a core previously analysed from the same basin (using magnetic susceptibility profiles), enabling tentative correlations to be suggested with other European terrestrial sequences and with the marine oxygen isotope record, back to marine isotope stage 16. Twelve AMS radiocarbon determinations from the upper part of the core, together with the identification of a series of reversed palaeomagnetic events within the Brunhes chron, support the proposed age model for the sequence. The sediments at Ioannina, unlike most of the other long terrestrial European sequences, are calcareous and contain mollusc and ostracod assemblages. Part of this project has involved a comprehensive review of Quaternary and modem aquatic faunas from the lake, as well as the description, illustration and critical assessment of several poorly-known endemic taxa. Faunal assemblage data have been used to provide valuable information concerning the variable response of lake-level to climatic change over time. Convincing new mollusc an evidence indicates low lake-levels at the Last Glacial Maximum, agreeing with regional pollen data, but conflicting with geomorphological evidence derived from Kastritsa, a well-documented nearby Palaeolithic cave site. It is suggested that this discrepancy may be a result of subsequent tectonic uplift of the rockshelter. In addition, stable isotopic analyses of both the ostracods and the bulk carbonate within the sediments have contributed towards deriving a comprehensive palaeoenvironmental history for the site. Although the study analysed physical, biological and geochemical aspects of the entire core, two distinct parts of the record were selected for more detailed investigation. High-resolution analysis over the last interglacial (the Eemian) has revealed evidence for a clear, two-step deglaciation at the beginning of the period, known from elsewhere as the Zeifen-Kattegat Oscillation. Climatic instability has also been detected within the full interglacial. Comparisons are drawn with a range of other Eemian records from across Europe, as well as the Greenland ice cores. High-resolution analysis of the period from the end of the last glacial to the present day has also revealed evidence for climatic instability. A cool and arid oscillation is demonstrated by several climatic proxies that may constitute the first recognition of the Younger Dryas stadial from Greece. A shorter, but more subdued cooling event has also been detected during the first half of the Holocene, which may correspond with a widespread climatic oscillation from high-resolution terrestrial, marine and ice core records that has been dated to between 7,500 and 8,000 years BP