Contemporary lead concentration and stable lead isotope ratio distribution in forest moss across the Czech Republic

Lead concentrations and stable lead isotopes (²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb) were measured in forest moss samples (Pleurozium schreberi or Scleropodium purum) collected at 273 sites across the Czech Republic during 2010. Continuously decreasing median Pb concentrations in moss were documented over the last two decades: 1995: 11 mg/kg, 2000: 5.66 mg/kg, 2005: 4.94 mg/kg and 2010: 2.85 mg/kg. Several local anomalies have decreased in scale, the overall regional distribution patterns remained, however, the same. The regional Pb isotope ratio distributions show that the ratios show little variation for a large central part of the country and provide the large-scale background isotope ratios for the Czech Republic of about ²⁰⁴Pb/²⁰⁶Pb = 0.0550, ²⁰⁶Pb/²⁰⁷Pb = 1.167, ²⁰⁶Pb/²⁰⁸Pb = 0.478 and ²⁰⁷Pb/²⁰⁸Pb = 0.409 for 2010. This background Pb isotope ratio signal in moss has been locally (900–7500 km²) modified by specific Pb isotopic ratio signals caused by deposition of Pb emissions from known local anthropogenic Pb emission sources, such as industrial combustion of local coal, and a variety of industrial enterprises (metallurgical, engineering and glass works). At some sites where mining of uranium and polymetallic ores took place the moss samples show also a locally specific Pb isotope signal. The in terms of area affected largest deviations in the Pb-isotope ratios, e.g., in the Bohemian Massif, may be due to the input of geogenic dust.     

Bioavailability of sediment-borne lead for ragworms (Hediste diversicolor) investigated by lead isotopes

The Seine estuary possesses a heavily industrialised catchment area that contrasts significantly with that possessed by the smaller Authie estuary. For both of these northern French estuaries, Pb isotopic compositions and concentrations have been determined on specimens of Hediste diversicolor (ragworms) and on HCl leachates performed on related mudflat sediment. Three sampling campaigns were completed in 2003. As expected, the reactive Pb obtained by 1 M HCl leaching, shows higher concentrations and a more anthropogenic signature in samples from the Seine estuary than in samples from the Authie. However, neither of the two sites is free from the influence of anthropogenic Pb. Possible contaminant sources are discussed through comparisons with previously published data. For the more highly contaminated Seine estuary, most of the ragworm Pb signatures are similar to those of the sediments. In contrast, ragworms from the Authie site exhibit a higher proportion of anthropogenic Pb than the corresponding sediments. Various hypotheses are discussed to explain this significant discrepancy: (1) analytical artifacts, (2) migration of ragworm populations, (3) diet and feeding behaviour, and as the most likely explanation (4) an unsuitable leaching method for the extraction of bioavailable Pb.     

Spatial relationships of salt distribution and related physical changes of underlying rocks on naturally weathered sandstone exposures (Bohemian Switzerland National Park,Czech Republic)

Efflorescence, case hardening, and granular disintegration represent common weathering features of Upper Cretaceous quartz sandstones exposed in the Bohemian Switzerland National Park (NW Bohemia, Czech Republic). Salt species (sulphates: gypsum (CaSO₄·2H₂O), potassium alum (KAl(SO₄)₂·12H₂O), tschermigite (NH₄Al(SO₄)₂·12H₂O), alunite (K(Al₃(SO₄)₂(OH)₆), and alunogen (Al₂(SO₄)₃·17H₂O), minor nitrates: nitrammite (NH₄NO₃)) determined by X-ray diffraction exhibit vertical and geographic zoning. More soluble salts (chlorides, nitrates, tschermigite) crystallize preferentially on the cliffs exposed to the south, whereas the north face is characterized by the presence of less soluble phases: gypsum and K(Al₃(SO₄)₂(OH)₆. Vertical zoning of salt distribution on natural outcrops differs from the salt distribution in masonry. Salt distribution near the base of the cliff (profile to about 2–2.5 m above the ground) is affected by capillary rise from the ground level (first maximum of water-soluble salts at the level of 1–1.5 m above the ground) and by percolation of precipitation through the overhanging rock sequence (second maximum of 2–2.5 m above the ground). Percolation of salt solution from higher parts is affected by the asperity of the rock surface. The concentration of salts (determined by ion exchange chromatography) correlates to the changes of physical properties: bulk porosity, microporosity and water absorption. The porosity, microporosity, moisture content and absorption generally increase with the increasing volume of sulphates and nitrates.     

Carbon isotopes to constrain the origin and circulation pattern of groundwater in the north-western part of the Bohemian Cretaceous Basin (Czech Republic)

The Bohemian Cretaceous Basin represents a complex hydrogeological system composed of several aquifers with very favourable hydrogeological properties. These aquifers have been exploited for many years. The sustainability of such resources might be guaranteed by well organised water management, which requires a detailed knowledge about the functioning of the hydrogeological system. Although many efforts have previously been made to evaluate groundwater residence time, the many intricate geochemical processes complicate groundwater dating. The current study clarifies the functioning of this complex hydrogeological basin using hydrogeochemical and isotopic investigations. Chemical data and a combination of ¹³C and ¹⁴C isotopes within the Cenomanian and the Turonian layers indicate groundwater interactions with deep-seated CO₂, rock matrix, surface waters and fossil organic matter. Very depleted δ¹³C values (average δ¹³C ∼ −13.4‰) suggest interactions with fossil organic matter, whereas enriched values account for the interaction with deep CO₂ gas ascending from the upper mantle via the numerous faults and fractures, and also, to a lesser extent, from calcite dissolution. Geochemical processes that take place in the system cause a clear depletion in ¹⁴C that greatly complicates groundwater residence time evaluation. Different dilution correction models have been applied considering the different C origins. The stable isotope content, mainly ¹⁸O values, indicates both the contribution of modern precipitation and the partial infiltration of palaeowaters during colder climatic conditions from the end of the Pleistocene. The apparent ¹⁴C groundwater ages range from modern to 11.1 ka BP, which suggests some post glacial infiltration from melting ice sheets. Finally, all the acquired information was used to propose a conceptual model of C origin within the basin.     

Mineralogical and geochemical (stable C and O isotopes) variability of marbles from the Moldanubian Zone (Bohemian Massif,Czech Republic): implications for provenance studies

Metacarbonates of the Moldanubian Zone (Bohemian Massif, Czech Republic) were studied to obtain qualitative and quantitative mineralogical-petrographic as well as stable isotopic data for the purpose of stone provenance studies, potentially applicable in material research studies of cultural heritage artefacts. Twenty-six samples from twelve different historical quarries, as well as two samples from historical artefacts, were analysed by both mineralogical-petrographic and geochemical methods including: polarizing microscopy, cathodoluminescence, scanning electron microscopy with microanalysis, petrographic image analysis, powder X-ray diffraction, and isotope ratio mass spectrometry. The petrographic characteristics allowed for the discrimination of groups of (1) calcitic marbles, (2) dolomitic marbles, and (3) carbonate–silicate rocks. These groups exhibit characteristic features such as (1) the presence/abundance of major rock-forming minerals, (2) grain geometric characteristics (specifically, mean carbonate grain size and index of grain size homogeneity), and (3) the presence of specific accessory phases. The content of non-carbonate minerals, some rock fabric parameters, as well as the carbon and oxygen isotope data exhibited significant variability, even within a single quarry in the case of some impure marbles and carbonate–silicate rocks. Although the carbon and oxygen isotopic ranges displayed overlaps among the quarries studied, the isotopic signatures throughout the Moldanubian Zone allowed for discrimination of a group of white calcitic marbles with high carbon and oxygen depletion, as well as white dolomite–calcitic marble with higher carbon isotope values when compared with other marble resources of the Bohemian Massif. A combination of the isotopic signature with detailed mineralogical-petrographic characteristics seems to provide sufficient information for discrimination of the Moldanubian marbles from one another. The provenance of the Vrchotovy Janovice artefact is very probably from the Rabí quarry, among the Moldanubian marbles. The provenance of the artefact from the Prague Klementinum was not definitively assigned; however, the Nehodiv quarry was considered its probable source locality.     

Holocene reactivations of catastrophic complex flow-like landslides in the Flysch Carpathians (Czech Republic/Slovakia)

Complex flow-like landslides (CFLLs) are important geomorphic agents of Late Quaternary mountain evolution in the Flysch Belt of the Outer Western Carpathians. The CFLLs are characterised by the upper section of deep-seated, retrogressive landslide of structurally unfavourably oriented rocks and lower sections composed of earthflows originated due to liquefaction of material accumulated from the upper slopes. Radiocarbon dating of organic matter incorporated into landslide debris or related deposits suggests that most of the CFLLs collapsed repeatedly throughout the Holocene with typical recurrence intervals of approximately 1–2 ka. Catastrophic landslides that occurred during extreme hydrometeorological events in recent decades displayed evidence of Holocene activity. Most of the CFLLs dammed and steepened adjacent valleys. Our chronological dataset is biased by erosion of older landforms, but most of the dated reactivations correlate to regional increases in humidity identified by previous paleoenvironmetal studies.     

Interaction of Cr(III) with the humus acids of soil,water, and bottom sediments

The interaction of Cr(III) with humus acids [fulvic (FA) and humic (HA) acids] was studied in the systems Cr(III)-FA, Cr(III)-HA, and Cr(III)-FA-HA. Chromium(III) reacts with FA extracted from the headwaters of the Moscow River and from the Krapivenka River (a tributary of Lake Seliger) to form a highly soluble high-molecular-weight Cr(III)-hydroxofulvate complexes with \(\bar \beta _{11} \) = 1.93 × 10⁶ and 5.70 × 10⁶, respectively. Humic acids extracted from peat in the Tver area and the sapropel of Lake Seliger behave as complexing sorbents with conditional affinity constants logβ = 3.78 and 3.23 for Cr(III) sorption at HA sites in the peat and sapropel, respectively. In the three-component system Cr(III)-FA-HA, the Cr(III) distribution coefficient between solution and precipitate is controlled by the pH value and FA content in the solution and decreases by 1–1.5 orders of magnitude with increasing fulvic acid content.     

The calcareous nannofossil record across the Late Cretaceous Turonian/Coniacian boundary,including new data from Germany,Poland, the Czech Republic and England

The proposed definition of the Turonian/Coniacian boundary, at the first occurrence of the inoceramid bivalve Cremnoceramus deformis erectus (Meek) (= Cremnoceramus rotundatus (sensu Tröger non Fiege)), prompted a rigorous study of the calcareous nannofossil events through this interval, both for calibration of the calcareous nannofossil biostratigraphy, and to provide an assessment of the suitability, in calcareous nannofossil terms, of the proposed stratotype section. New calcareous nannofossil data are presented here, detailing the biostratigraphy of the boundary interval from four locations. These include the candidate boundary-stratotype, the Salzgitter-Salder Quarry section (northern Germany), as well as the Slupia Nadbrzezna outcrop (central Poland), a potential secondary reference section. Also included is the Brezno Pd-1 Borehole and outcrops in the Brezno Formation (= Priesener Schichten) type-area (north-western Czech Republic), which represents an original boundary candidate (Copenhagen Stage Boundaries Meeting, 1983), and the Langdon Stairs coastal section (south-eastern England), part of the British Chalk succession. The calcareous nannofossil events derived from each section provide a sequence across the boundary of (in stratigraphical order): below the boundary, the first occurrence of Lithastrinus septenarius followed by that of Broinsonia parca expansa; above the boundary, the last occurrence of Helicolithus turonicus followed by the first occurrence of Micula staurophora (= Micula decussata of some authors). This places the boundary within Nannofossil Subzone UC9c. A similar sequence of events has previously been determined from sections in north-eastern England and in the south-eastern Indian Ocean. The presented data and correlations suggest that either the Salzgitter-Salder Quarry section or the Slupia Nadbrzezna outcrop section would make a suitable Global Stratotype Section for the Turonian/Coniacian boundary, as far as calcareous nannofossils are concerned. The use of the calcareous nannofossil Marthasterites furcatus, widely quoted as an indicator of this boundary, is discussed and proved to be untenable.     

Impact of the deeper geological basement on soil gas and indoor radon concentrations in areas of Quaternary fluvial sediments (Bohemian Massif,Czech Republic)

The relationship of soil gas radon Rn²²² and indoor radon was studied within the Quaternary fluvial sediments of the Czech Republic. The processing of data selection from the radon database of the Czech Geological Survey and indoor radon data (database of the National Radiation Protection institute) has proved the concentration dependence of radon in Quaternary fluvial sediments on deeper bedrock. The ArcGIS processing was accompanied by the field verification in five profiles, intersecting the granitoid Central Bohemian Plutonic Complex and its rim rock types. Both theoretical and experimental results show dependence of soil gas radon and indoor radon concentrations in Quaternary fluvial sediments on deeper geological basement, thus leading to the conclusion that the lateral transport of Quaternary sediments does not play such a dominant role in radon concentrations, as was thought previously. This fact will enable to determine precisely the radon index of Quaternary sediments (in the Czech radon mapping classified as an intermediate index) into three categories according to the lithology of their geological basement.     

Magmatic history of granite-derived mylonites from the southern Desná Unit (Silesicum, Czech Republic)

Summary In the southern part of the Hruby Jeseník Mts. (Silesicum, Bohemian Massif) granitic orthogneisses and quartz-feldspars mylonites occur that were variously deformed, metamorphosed and imbricated with the overlaying Devonian volcano-sedimentary complex during the Variscan orogeny. Based on combined mapping, petrologic and geochemical studies, three main rock groups are distinguished. The fairly primitive nature of the tonalite suite is shown by low ⁸⁷Sr/⁸⁶Sr₅₅₀ ratios (0.7034–0.7038) and positive ε _Nd ⁵⁵⁰ values (+3.8 and +3.1). Isotopic composition of the metagranite suite is similar (ε _Nd ⁵⁵⁰ = +1.9 to +2.9). Both suites probably belong to a single Cadomian calc-alkaline tonalite–granite association, which can be correlated with acid-intermediate plutonic rocks of the eastern Brunovistulicum (Slavkov Terrane). All these units are interpreted as representing dismembered fragments of the same continental margin magmatic arc system. The leucogranite suite is most likely early Variscan in age. The initial Nd isotopic composition (ε _Nd ³³⁰ = +0.8 and +2.3) is consistent with its formation by a Variscan remelting of the metaigneous Cadomian crust represented by the rocks of the tonalite–granite association. The within-plate granite affinity of the leucogranite suite is most likely related to the break-up of the Brunovistulicum during the Variscan orogeny.     

Grain size,geochemistry and organic pollutants in modern fluvial deposits in eastern Moravia (Czech Republic)

Modern fluvial deposits from both small and large rivers were studied at 14 monitoring sites over 2 years (4 successive sampling seasons) in the area of eastern Moravia (Czech Republic). Grain size, geochemistry, content of persistent organic pollutants (PAHs, PCBs, HCHs, DDTs, HCBs and PeCB) and TOC were examined with the aim to understand their mutual relations and seasonal variations in sediment character and pollutant content. Sand and silt fraction predominate and the clay content is relatively low. Differences in provenance for various river systems were recognised. Both regional and seasonal variations in terms of content of persistent organic pollutants were documented. The content of TOC and mud was shown to play an important role in the accumulation of chlorinated persistent organic pollutants PCBs, HCHs, DDTs and HCB.     

黑河流域基岩回弹值(施密特锤)的空间分布特征 及其指示意义

基岩风化体现了构造与气候对地貌演化过程的共同作用。晚新生代的强烈构造抬升和干旱的气候条件,使得祁连山成为研究基岩风化与地貌演化过程的理想场所。借用施密特锤系统地研究了基岩回弹值（R）在黑河流域内不同海拔高度内的变化,结果显示流域平均的R值与侵蚀速率具有较好的相关性,意味着R值可以作为风化强度空间变化的代用指标。研究区内各种岩石类型的R值变化相差不大,说明岩性对R值的影响较小。进一步将R值与气候因子和区域地形进行比较发现：气温、降水与NDVI对R值的影响较强;坡度与局地高差对R值影响较弱,高程与R值在海拔小于3 800 m时呈现负相关关系,在大于3 800 m时呈现正相关关系。     

FTIR-derived characteristics of fossil-gymnosperm leaf remains of Cordaites principalis and Cordaites borassifolius (Pennsylvanian, Maritimes Canada and Czech Republic)

Cordaites principalis and Cordaites borassifolius, gymnosperm trees of the Carboniferous, are distinguished based on compression and cuticular morphology. A new distinction between them is suggested on the basis of differences in functional groups. Cuticular and compression spectra of C. borassifolius have lower CH₂/CH₃ ratios, suggesting more branched aliphatic chains in comparison with cuticles and compressions of C. principalis. Other differences are observed with Fourier transform infrared spectroscopy (FTIR) technique, but they vary from sample to sample of the two species to suggest other than chemotaxonomic-based sources of variations.     

P–T evolution and reaction textures in retrogressed eclogites from Svetlik, the Moldanubian Zone (Czech Republic)

Summary Lenses and pods of mafic rocks from the Monotonous Unit near Svetlik are characterized by eclogite facies mineral assemblages; however some inclusion patterns (oriented quartz rods in clinopyroxene and cuboids of disordered graphite in garnet) that are usually known from ultra-high pressure rocks were also observed in one sample. Conventional thermobarometry yielded maximum P–T conditions of 2.0–2.5 GPa and 750 °C. Decompression and heating at amphibolite and granulite facies conditions resulted in the formation of at least five distinct types of symplectites. These include symplectitic intergrowth of ilmenite and clinopyroxene after titanite, described here for the first time from the Moldanubian Zone. In addition, symplectites of plagioclase and biotite with accessory amounts of spinel after tabular pseudomorphs (after phengite?) are also reported here. Mass balance relations indicate that symplectites of diopside + plagioclase after omphacite and plagioclase + spinel (sapphirine) after kyanite + garnet, formed by nearly isochemical reactions. All other symplectite-forming reactions were allochemical and were accelerated by the presence of fluid in the primary phases. Preserved zoning pattern in garnet with high compositional gradient in some samples suggests that the rocks were affected briefly by granulite facies overprint.     

Soil mercury distribution in adjacent coniferous and deciduous stands highly impacted by acid rain in the Ore Mountains,Czech Republic

Forests play a primary role in the cycling and storage of mercury (Hg) in terrestrial ecosystems. This study aimed to assess differences in Hg cycling and storage resulting from different vegetation at two adjacent forest stands - beech and spruce. The study site Načetín in the Czech Republic's Black Triangle received high atmospheric loadings of Hg from coal combustion in the second half of the 20th century as documented by peat accumulation rates reaching 100 μg m⁻² y⁻¹. In 2004, the annual litterfall Hg flux was 22.5 μg m⁻² y⁻¹ in the beech stand and 14.5 μg m⁻² y⁻¹ in the spruce stand. Soil concentrations and pools of Hg had a strong positive relation to soil organic matter and concentrations of soil sulfur (S) and nitrogen (N). O-horizon Hg concentrations ranged from 245 to 495 μg kg⁻¹ and were greater in the spruce stand soil, probably as a result of greater dry Hg deposition. Mineral soil Hg concentrations ranged from 51 to 163 μg kg⁻¹ and were greater in the beech stand soil due to its greater capacity to store organic carbon (C). The Hg/C ratio increased with depth from 0.3 in the O-horizon to 3.8 μg g⁻¹ in the C horizon of spruce soil and from 0.7 to 2.7 μg g⁻¹ in beech soil. The Hg/C ratio was greater at all mineral soil depths in the spruce stand. The organic soil Hg pools in beech and spruce stands (6.4 and 5.7 mg m⁻², respectively) were considerably lower than corresponding mineral soil Hg pools (39.1 and 25.8 mg m⁻²). Despite the important role of S in Hg cycling, differences in soil Hg distribution at both stands could not be attributed to differences in soil sulfur speciation.     

Subdivision of the Lochkovian Stage based on conodont faunas from the stratotype area (Prague Synform,Czech Republic)

Relatively rich conodont faunas from sections in the Prague Synform (Barrandian area, Czech Republic) include a number of indexes and other important guide conodonts that can be correlated with other regions, especially with Nevada and the Spanish Central Pyrenees. The collation and detailed correlation of conodont data from the Lochkovian in two parallel sections in the Požáry quarries, together with biostratigraphic control of additional data from several (incomplete) sections with changing facies development, is the basis for a new detailed regional biozonal scale for the Lochkovian in the Prague Synform. The new subdivision follows, with modification, the global threefold conodont subdivision of the Lochkovian. Data from the Prague Synform enable further detailed subdivision of the lower, middle and upper Lochkovian into small‐scale units. The conodont distribution shows a large proportional discrepancy between the late Lochkovian elsewhere; the conodont record in the latest Lochkovian in the Prague Synform area, which appears to be rather restricted and requires further discussion. Copyright © 2012 John Wiley & Sons, Ltd.     

Quartz and feldspar zoning in the eastern Erzgebirge volcano-plutonic complex (Germany, Czech Republic): evidence of multiple magma mixing

Zoned quartz and feldspar phenocrysts of the Upper Carboniferous eastern Erzgebirge volcano-plutonic complex were studied by cathodoluminescence and minor and trace element profiling. The results verify the suitability of quartz and feldspar phenocrysts as recorders of differentiation trends, magma mixing and recharge events, and suggest that much heterogeneity in plutonic systems may be overlooked on a whole-rock scale. Multiple resorption surfaces and zones, element concentration steps in zoned quartz (Ti) and feldspar phenocrysts (anorthite content, Ba, Sr), and plagioclase-mantled K-feldspars etc. indicate mixing of silicic magma with a more mafic magma for several magmatic phases of the eastern Erzgebirge volcano-plutonic complex. Generally, feldspar appears to be sensitive to the physicochemical changes of the melt, whereas quartz phenocrysts are more stable and can survive a longer period of evolution and final effusion of silicic magmas. The regional distribution of mixing-compatible textures suggests that magma mingling and mixing was a major process in the evolution of these late-Variscan granites and associated volcanic rocks.

Quartz phenocrysts from 14 magmatic phases of the eastern Erzgebirge volcano-plutonic complex provide information on the relative timing of different mixing processes, storage and recharge, allowing a model for the distribution of magma reservoirs in space and time. At least two levels of magma storage are envisioned: deep reservoirs between 24 and 17 km (the crystallisation level of quartz phenocrysts) and subvolcanic reservoirs between 13 and 6 km. Deflation of the shallow reservoirs during the extrusion of the Teplice rhyolites triggered the formation of the Altenberg-Teplice caldera above the eastern Erzgebirge volcano-plutonic complex. The deep magma reservoir of the Teplice rhyolite also has a genetic relationship to the younger mineralised A-type granites, as indicated by quartz phenocryst populations. The pre-caldera biotite granites and the rhyodacitic Schönfeld volcanic rocks represent temporally and spatially separate magma sources. However, the deep magma reservoir of both is assumed to have been at a depth of 24–17 km. The drastic chemical contrast between the pre-caldera Schönfeld (Westfalian B–C) and the syn-caldera Teplice (Westfalian C–D) volcanic rocks is related to the change from late-orogenic geotectonic environment to post-orogenic faulting, and is considered an important chronostratigraphic marker.     

Middle/Late Cambrian intracontinental rifting in the central West Sudetes,NE Bohemian Massif (Czech Republic): geochemistry and petrogenesis of the bimodal metavolcanic rocks

The Early Palaeozoic East Krkonoše Complex (EKC) situated in the central West Sudetes, NE Bohemian Massif, is a volcano‐sedimentary suite containing abundant mafic and felsic volcanics metamorphosed to greenschist facies. The trace element distribution patterns and Nd isotope signatures (E_Nd500 = + 3.1 to + 6.6) of the metabasites (metabasalts) indicate that they may be related to a rising mantle diapir associated with intracontinental rifting. At the early stage, limited melting of an upwelling asthenosphere produced alkali basalts and enriched tholeiites which compositionally resemble oceanic island basalts. A later stage of rifting with larger degrees of melting at shallower depths generated tholeiitic basalts with E‐MORB to N‐MORB characteristics. The values of (⁸⁷Sr/⁸⁶Sr)_i = 0.706 and E_Nd500 = − 5 ±1 of the porphyroids (metarhyolites) as well as the lack of rocks with intermediate compositions suggest that the felsic rocks were formed by a partial melting event of continental crust triggered by mantle melts. The geochemistry of the EKC bimodal metavolcanics and their association with abundant terrigenous metasediments suggest that the felsic–mafic volcanic suite was generated during intracontinental rifting. This process, widespread in Western and Central Europe during the Early Palaeozoic, is evidence of large‐scale fragmentation of the northern margin of the Gondwana supercontinent. Copyright © 2001 John Wiley & Sons, Ltd.     

Oxygen and carbon stable isotopes in otoliths record spatial isolation of Patagonian toothfish (Dissostichus eleginoides)

Strong contrasts in ambient isotope ratios and in diet suggest stable isotopes in the otoliths of oceanic fish can resolve water masses and geographic areas, promising a powerful multivariate approach for examining population structure and provenance. To test this, whole otoliths were taken from Patagonian toothfish (Dissostichus eleginoides) sampled off the Patagonian Shelf and South Georgia, on either side of a population boundary, and otolith δ¹⁸O and δ¹³C values were measured to see if they could distinguish South American-caught fish from those taken in the Antarctic. Values of otolith δ¹⁸O and δ¹³C predicted capture area with 100% success, validating their use for distinguishing provenance and corroborating the prior evidence of population isolation. Values of δ¹⁸O in the otoliths reflected ambient values as well as seawater temperature: low values in Patagonian Shelf fish were consistent with exposure to Antarctic Intermediate Water (AAIW), and high values in South Georgia fish were consistent with exposure to Circumpolar Deep Water (CDW). In contrast, differences in otolith δ¹³C appeared to reflect diet: relative depletion of otolith δ¹³C at South Georgia compared to the Patagonian Shelf were most likely linked to differences in sources of metabolic carbon, as well as δ¹³C in dissolved inorganic carbon (DIC) of seawater. These contrasting properties strongly suggest that stable isotopes can resolve the provenance of toothfish from Antarctic sampling areas that hitherto have been difficult to separate. These results show that, by using the chemistry recorded in otoliths, researchers can exploit biogeochemical variation in fully marine environments to examine the spatial ecology of oceanic fish.