mutvei s solution an ideal agent for resolving microgrowth structures of biogenic carbonates accretionary hard parts of many organisms provide excellent archives of past climate and environmental conditions or life history traits variable growth rates function as environmental and physiological proxies and growth increments as calendars recognition of growth structures is thus a prime necessity for sclerochronological studies here we present a new handy easy to use and time efficient technique that resolves annual and sub annual growth structures in skeletons of a wide range of different organisms mutvei s solution simultaneously etches biogenic carbonates and calcium phosphates fixates the soluble and insoluble organic matrices and fibers and stains mucopolysaccharides it produces a filigreed three dimensional relief of etch resistant ridges growth lines and etched depressions growth increments and stains skeletal growth structures in shadings of blue growth lines stand out as crisp darker blue stained lines reflected optical light microscopy axial and oblique illumination and scanning electron microscopy can be used to analyze the microgrowth structures we demonstrate the use of the technique on hard tissues of various marine and freshwater bivalves a coral a sclerosponge a barnacle gastropods a cephalopod a fish otolith and a whale s ear bone this technique may be of interest for paleoclimatologists geochemists and biologists it can significantly expand the use of biogenic hard parts as environmental and physiological indicators because it reveals microgrowth structures of biogenic skeletons that potentially form on a periodic basis and thus function as calendars

oxygen isotope composition of modern and archaeological otoliths from the estuarine hardhead catfish ariopsis felis and their potential to record low latitude climate change abstract shells and otoliths fish ear bones from archaeological deposits of pine island southwest florida provide valuable archives of ecological patterns climate change and associated human responses many remains from these deposits that can be used for climate reconstruction are from estuarine animals the challenge in using oxygen isotope composition of their carbonate hard parts lies in deconvoluting the effects of temperature and salinity mixing of fresh and saltwater each having different isotopic compositions otoliths of the hardhead catfish ariopsis felis linneaus 1766 may provide a record of winter temperature without the complication of salinity variation because this fish spends winter months in waters of marine to near marine salinities hence 18 o water can be constrained when employing published temperature equations here we present geochemical data from modern and archaeological otoliths to evaluate whether they preserve winter temperature a modern catfish was caught near pine island sound and the otoliths lapilli removed archaeological otoliths from the 2nd 3rd century ad falling within the roman optimum ro and the 13th 14th century ad falling within the little ice age lia were obtained from the florida museum s collections oxygen isotope compositions were converted to temperature using published temperature equations and assuming 1 for gulf water isotopic compositions for the modern otolith range from 3 55 to 0 29 the lia otolith ranges from 3 92 to 0 52 and the ro otolith ranges from 1 80 to 0 84 all three otoliths record winter temperature 20 c similar to modern conditions calculated summer temperatures for the modern and lia otoliths 40 c are overestimated and reflect the combined influence of temperature and salinity when catfish inhabit brackish estuarine waters during their reproductive season in contrast summer temperature estimates for the ro otolith are similar to modern conditions indicating estuarine water during the summer was close to 1 this result suggests that seasonal rainfall patterns during the time period represented by the ro otolith were different than today such that the summer wet season was not prevalent

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

non linear variation with salinity of sr ca and mg ca ratios in water and aragonitic bivalve shells and implications for paleosalinity studies abstract fresh water and sea water usually differ considerably in their sr ca and mg ca ratios this suggests that these ratios in fossil shells could be used to determine paleosalinities calculation of the sr ca and mg ca ratios in mixtures of sea water and average fresh water using a mixing equation shows that the ratios first increase rapidly with salinity to about 100 but subsequently remain nearly constant the source of most of the ca sr and mg in mixtures of fresh and sea water is the sea water thus except at low salinities the trace element to ca ratio of mixtures differs little from that in sea water analysis both of waters across a spectrum of salinities and of aragonitic mollusc shells growing in water of various salinities conforms to the predicted pattern however trace element to ca ratios offer potential for paleosalinity determination in waters of salinity below about 100

tropical sea surface temperatures for the past four centuries reconstructed from coral archives most annually resolved climate reconstructions of the common era are based on terrestrial data making it a challenge to independently assess how recent climate changes have affected the oceans here as part of the past global changes ocean2k project we present four regionally calibrated and validated reconstructions of sea surface temperatures in the tropics based on 57 published and publicly archived marine paleoclimate data sets derived exclusively from tropical coral archives validation exercises suggest that our reconstructions are interpretable for much of the past 400 years depending on the availability of paleoclimate data within and the reconstruction validation statistics for each target region analysis of the trends in the data suggests that the indian western pacific and western atlantic ocean regions were cooling until modern warming began around the 1830s the early 1800s were an exceptionally cool period in the indo pacific region likely due to multiple large tropical volcanic eruptions occurring in the early nineteenth century decadal scale variability is a quasi persistent feature of all basins twentieth century warming associated with greenhouse gas emissions is apparent in the indian west pacific and western atlantic oceans but we find no evidence that either natural or anthropogenic forcings have altered el nino southern oscillation related variance in tropical sea surface temperatures our marine based regional paleoclimate reconstructions serve as benchmarks against which terrestrial reconstructions as well as climate model simulations can be compared and as a basis for studying the processes by which the tropical oceans mediate climate variability and change

coupled north atlantic slope water forcing on gulf of maine temperatures over the past millennium to investigate ocean variability during the last millennium in the western gulf of maine gom we collected a 142 year old living bivalve arctica islandica l in 2004 and three fossil a islandica shells calibrated 14cams 1030 78 ad 1320 45 ad 1357 40 ad for stable isotope and growth increment analysis a statistically significant relationship exists between modern gom temperature records shell isotope derived 30 m r 0 79 p 0 007 prince 5 50 m r 0 72 p 0 019 boothbay harbor sst r 0 76 p 0 011 and labrador current lc transport data from the eastern newfoundland slope during 1993 2003 in all cases as lc transport increased gom water temperatures decreased the following year decadal trends in the north atlantic oscillation nao and the atlantic multidecadal oscillation amo influence gom water temperatures in the most recent period with water temperatures decreasing during nao and amo negative modes most likely linked to lc transport and gulf stream interaction mean shell derived isotopic changes 18oc during the last 1 000 years were 0 47 and likely reflect a 1 2 c cooling from 1000 ad to present based on these results we suggest that observed cooling in the gom during the last millennium was due to increased transport and or cooling of the lc and decreased gulf stream influence on the gom

coralline red algae as high resolution climate recorders most high resolution proxy based paleoclimate research has concentrated on tropical oceans while mid and high latitude marine regions have received less attention despite their importance in the global climate system at present sclerochronological analyses of bivalve mollusks supply the bulk of annual to subannual resolution extratropical marine climate data even though interpretation is complicated by a slowdown of growth with increasing shell age hence in order to address the need for additional high resolution proxy climate data from extratropical regions we conducted the first year long in situ field calibration of the coralline red alga clathromorphum compactum in the gulf of maine united states coralline red algae are widely distributed in coastal regions worldwide and individual calcified plants can live continuously for several centuries in temperate and subarctic oceans stable oxygen isotopes extracted at subannual resolution from growth increments of monitored specimens of c compactum relate well to in situ measured sea surface temperatures during the may to december calcification period highlighting the suitability of coralline red algae as an extratropical climate archive furthermore there is a strong correlation between a 30 yr 18 o record of c compactum and an instrumental sea surface temperature record r 0 58 p 0 0008 and a proxy reconstruction derived from the bivalve arctica islandica collected in the central gulf of maine r 0 54 p 0 002

continuous marine radiocarbon reservoir calibration and the 13c suess effect in the irish sea results from the first multi centennial shell based marine master chronology abstract the identification in various proxy records of periods of rapid decadal scale climate change over recent millennia together with the possibility that feedback mechanisms may amplify climate system responses to increasing atmospheric co2 highlights the importance of a detailed understanding at high spatial and temporal resolutions of forcings and feedbacks within the system such an understanding has hitherto been limited because the temperate marine environment has lacked an absolute timescale of the kind provided by tree rings for the terrestrial environment and by corals for the tropical marine environment here we present the first annually resolved multi centennial 489 year absolutely dated shell based marine master chronology the chronology has been constructed by detrending and averaging annual growth increment widths in the shells of multiple specimens of the very long lived bivalve mollusc arctica islandica collected from sites to the south and west of the isle of man in the irish sea the strength of the common environmental signal expressed in the chronology is fully comparable with equivalent statistics for tree ring chronologies analysis of the 14c signal in the shells shows no trend in the marine radiocarbon reservoir correction r although it may be more variable before 1750 the 13c signal shows a very significant r2 0 456 p

reconstructing mid to high latitude marine climate and ocean variability using bivalves coralline algae and marine sediment cores from the northern hemisphere quantifying the role and contribution of the world s oceans in past present and future global change is an essential goal in climate paleoclimate and environmental studies although the global oceans interact and influence climate greatly the marine environment is substantially under represented in key climate assessment reports especially during the last millennium ipcc 2007 see palaeoclimate chapter 6 6 the last 2000 years the under representation of marine records in key climate documents likely results from the often imprecise chronologies associated with many marine based archives which greatly hinders singular climate comparisons lag lead phasing relationships with well dated and or annually resolved archives however several marine archive records have excellent chronological constraint in particular many marine bivalve taxa and coralline algae have annual increments that form within their carbonate framework that can be used to establish an absolutely dated chronology via cross dating techniques from the marine environment additionally in some cases where sedimentation rates are high and alternative chronological dating methods exist e g tephrochronology other than radiocarbon measurements often greater than 40 years uncertainty sediment archives can provide continuous sub decadal records of environmental change for centuries to millennia this brief introductory article and accompanying special issue will focus on the utilization of bivalves coralline algae and high resolution marine sediment cores in paleoclimate and environmental studies within the most recent millennium with a focus on the northern hemisphere

determination of sea surface temperatures using oxygen isotope ratios from phorcus lineatus da costa 1778 in northern spain implications for paleoclimate and archaeological studies changes in oxygen isotope ratios from shell carbonates are mainly dependent on sea surface temperature which enables the estimation of temperatures during periods of shell growth and helps to dete

climate records from a bivalved methuselah arctica islandica mollusca iceland we measured annual shell growth rates of a 374 year old radiometrically confirmed bivalve mollusk specimen of arctica islandica linnaeus this bivalve represents the oldest ever reported individual animal in addition we analyzed 1051 individual powder samples from ontogenetic years two to 40 80 of the entire shell height for isotope analyses oxygen and carbon isotopes exhibit clear intra annual cycles the highest measured carbon isotope values on average 2 73x occurred during summer i e during maximum primary productivity the d 18 oaragonite derived temperature time series cover the period of ad 1496 1533 temperatures calculated from oxygen isotopes ranged from 4 5 to 9 3 8c and exhibit a mean value of 6 2 8c the latter coincides well with the 1854 2003 mean value of 6 81 8c for sea surface temperature between february and september growing season of a islandica neither oxygen nor carbon isotopes exhibit age related unidirectional trends however d 13 caragonite and d 18 oaragonite values fluctuated at decadal periods of four six and eight to nine years nao type periods as well as 12 14 years which may represent teleconnections to cycles in the tropical atlantic annual shell growth is positively correlated to intra annual d 18 oaragonite minima i e warm summer temperatures r 2 0 34 and to intra annual d 13 caragonite minima higher food supply r 2 0 42 using a linear multiregression model 65 of the variation in annual shell growth can be explained by summer temperature and food supply the formation of extremely narrow annual increments coincides with major volcanic eruptions e g tambora 1815 a period of extremely variable growth occurred during the culmination of the little ice age in iceland between ca ad 1550 and 1620 shell growth during ad 1765 1780 however was characterized by very little year to year variability probably as the result of extremely mild climate near the end of the little ice age this study demonstrates that shells of a islandica provide

stone age midden deposition assessed by bivalve sclerochronology and radiocarbon wiggle matching of arctica islandica shell increments abstract sclerochronology the study of the skeletal diaries of mollusks and corals is a high resolution geochronological tool of versatile usage in archaeology and paleontology with increasingly growing opportunities much of the recent efforts have concentrated on building multi centennial bivalve growth records using annually deposited increments in the holocene shells comparable to tree ring chronologies in the context of geoarchaeology the hitherto unachieved potential includes the application of sclerochronology to reconstruct long term settlement histories here we contribute to both of these critical issues by presenting the first multi shell sclerochronology constrained by methods originally developed in tree ring research using anthropogenically deposited bivalve shells of arctica islandica excavated from a stone age midden in north norway our systematic chronological approach to shell growth histories lays the foundation for a multi dimensional dating framework that interacts between the incremental radioisotopic and stratigraphic evidence we show how the crossdating within and between the single shell records yields a 155 year multi shell sclerochronology supported by the 14 c ams dates that demonstrates minimum midden accumulation of 82 years and a depositional rate of 0 3 cm yr sclerochronology paves the way for radiocarbon wiggle matching which narrows the probabilistic 2 uncertainty range for the oldest and youngest 14 c ams dates to 3150 2980 and 3060 2890 bc respectively we attribute the spectral characteristics of the chronology primarily to the north atlantic oscillation suggesting essentially similar influences of climate variability on the stone age culture and our own society

marine mollusc exploitation in mediterranean prehistory an overview abstract marine molluscs have been recovered from sites around the mediterranean sea dating as far back as the lower palaeolithic when hominins might have started consuming them ca 300 ka during the middle palaeolithic and the early upper palaeolithic humans homo neanderthalensis and homo sapiens ate molluscs at many sites across the mediterranean at least as early as the last interglacial although the scale of this exploitation is still unclear due to biases produced in the coastal archaeological record by late glacial and post glacial sea level rise the exploitation of marine molluscs apparently increased in the late glacial and early holocene when humans collected them in relatively large quantities and from all available ecosystems the consumption of shellfish and of other small animals aquatic and continental probably contributed to the success of the flexible and opportunistic subsistence strategies adopted by mediterranean hunter gatherers for much of prehistory this is particularly evident in later foraging economic systems i e late upper palaeolithic and mesolithic in which coastal resources probably acted as buffers against the negative outcomes of environmental and anthropogenic impacts on available resources

advancements in the use of speleothems as climate archives abstract speleothems have become a cornerstone of the approach to better understanding earth s climatic teleconnections due to their precise absolute chronologies their continuous or semicontinuous deposition and their global terrestrial distribution we review the last decade of speleothem related research building off a similar review by mcdermott 2004 in three themes i investigation of global teleconnections using speleothem based climate reconstructions ii refinement of climate interpretations from speleothem proxies through cave monitoring and iii novel technical methods of speleothem based climate reconstructions speleothem records have enabled critical insight into the response of global hydroclimate to large climate changes this includes the relevant forcings and sequence of climatic responses involved in glacial terminations and recognition of a global monsoon response to climate changes on orbital and millennial time scales we review advancements in understanding of the processes that control speleothem 13 c values and introduce the idea of a direct atmospheric pco 2 influence we discuss progress in understanding kinetic isotope fractionation which with further advances may help quantify paleoclimate changes despite non equilibrium formation of speleothems this feeds into the potential of proxy system modeling to consider climatic hydrological and biogeochemical processes with the objective of quantitatively interpreting speleothem proxies finally we provide an overview of emerging speleothem proxies and novel approaches using existing proxies most recently technical advancements made in the measurement of fluid inclusions are now yielding reliable determinations of paleotemperatures

oxygen isotopes from phorcus osilinus turbinatus shells as a proxy for sea surface temperature in the central mediterranean a case study from malta abstract the marine topshell phorcus osilinus turbinatus is a common component of many archaeological sites in the mediterranean this species has been successfully used as a palaeoclimate proxy in italy to test whether 18 o from p turbinatus shells can serve as a reliable palaeoclimate archive for other regions of the mediterranean we collected live p turbinatus from the northeast coast of malta each month for a year the 18 o shell values of the outermost growth increments of these live collected shells ranged between 0 4 and 2 4 these values correspond to growing temperatures calculated from shell edge 18 o of between 15 c and 27 c calculated shell edge sea surface temperatures are highly correlated with instrumental records of sea surface temperature recorded over the period of collection the individuals analysed for this study are smaller than p turbinatus from populations studied elsewhere in the mediterranean nonetheless 18 o shell provides a robust record of sea surface temperatures suggesting that smaller younger shells in archaeological deposits can still provide reliable palaeothermometry records this study extends the upper growth limit p turbinatus by 2 c compared with the previous studies of p turbinatus in the mediterranean and suggests that contrary to the previous studies growth shutdown does not occur in all p turbinatus when sea surface temperatures exceed 25 c this may reflect the higher sample resolution that can be obtained from smaller faster growing shells or it may reflect actual higher growth tolerances of p turbinatus populations in malta by showing that p turbinatus precipitate their shells in 18 o equilibrium with surrounding sea water this study reinforces the potential for the stable isotope chemistry of p turbinatus shells preserved in mediterranean archaeological sites to provide a window into the climate and seasonality regimes of the past

precise temporal correlation of holocene mollusk shells using sclerochronology abstract annual growth bands of mollusk shells record several types of paleoenvironmental information including geochemical proxies for water properties and morphological characteristics of growth and mortality sclerochronology the marine counterpart of dendrochronology offers a way to link individual shells together to form long continuous records of such parameters it also allows for precise dating of recent shells and identification of contemporaneous fossil individuals the longevity of the ocean quahog arctica islandica commonly 100 yr makes this species well suited for sclerochronology band width records of contemporaneous a islandica specimens from the same region exhibit high correlations 0 60 0 80 for spans of 30 bands indicating some common environmental influences on shell growth by adopting several strict criteria fossil dead collected shells can be linked into composite sclerochronologies a seven shell 154 yr chronology was constructed for georges bank using three live collected and four dead collected shells band width matching indicates that the dead collected individuals died in a d 1950 1971 1978 and 1989 sclerochronological age assignments were verified using aspartic acid racemization dating construction of a 1000 yr sclerochronology is judged to be feasible using the described methods

coralline algae are global palaeothermometers with bi weekly resolution abstract high resolution palaeoclimate data are required for the holocene to resolve differences recorded by current proxies the pole to pole distribution of rhodoliths coralline algae with their annual and sub annual calcite bands make these attractive candidates for such a role these bands contain climate information in the form of elemental traces in situ temperature ist was recorded at two rhodolith beds for 1 5 years the concentrations of mgco 3 and srco 3 mol deposited in lithothamion glaciale and phymatolithon calcareum over this 18 month period were determined using electron and ion microprobes highly significant linear relationships exist between mg sr and ist as well as sea surface temperature calibration between mg concentration and ist was used to obtain a 2 year temperature profile from a subfossil rhodolith thallus indicating half the seasonal peak to peak temperature amplitude earlier during the holocene than the present day both slow growing species 1 allowed sampling resolutions of 23 year 1 which is equivalent to 1 reading every 2 weeks sub monthly mg and sr records in rhodoliths make them unique globally distributed palaeothermometers which may help refine regional climate histories during the holocene

further amino acid racemisation evidence for glacial age multiple lowstand deposition on the new south wales outer continental shelf southeastern australia abstract amino acid racemisation aar analyses total acid hydrolysate on the fossil bivalve molluscs pecten fumatus and glycymeris radians from 10 vibracores from the new south wales continental shelf in present water depths ranging between 123 and 152 m below present sea level and extending some 300 km of latitude provide further evidence for multiple lowstand deposition at times of glacial maxima the extent of racemisation as determined for the amino acids alanine ala aspartic acid asp leucine leu and valine val indicate that the fossil molluscs plot into three principal aminogroups of contrasting age and in general accord with results previously obtained from three vibracores for the molluscs p fumatus and placamen placidium comparable extents of racemisation are evident in the fossil molluscs from the different cores providing a framework for a shelf wide regional aminostratigraphy fossil molluscs of the past three glacial maxima marine oxygen isotope stages ois 2 6 and 8 are identified within the vibracores based on amino acid racemisation evidence calibrated by radiocarbon dating of the same shell associations and correlation with independently dated deposits in southeastern australia the results extend the known geographical range of glacial age lowstand deposits on the mid and outer continental shelf of new south wales southeastern australia and help constrain the magnitude of sea level fall for the past three glaciations to at least 120 m below present sea level the extent of racemisation in specimens of p fumatus of marine ois 6 age with strongly indurated sediment encrustations adhering to the shell surfaces is significantly higher than for shells of equivalent age but without adhering sediment the higher extent of racemisation is consistent with a higher diagenetic temperature history for these specimens by implication these individual shells are likely to have remained within a relatively shallow water environment during the last glacial maximum resulting in the high degree of sediment induration and the higher extent of racemisation

food for thought mathematical approaches for the conversion of high resolution sclerochronological oxygen isotope records into sub annually resolved time series abstract oxygen isotope 18 o records of incrementally banded marine calcifiers provide high resolution information about modern and past environmental conditions however given their biological origin these records are often distorted by ontogenetic and seasonal growth pattern to evaluate their reliability many studies correlate skeletal 18 o records with instrumentally measured time series of environmental conditions using a variety of methods to recalculate their temporal framework lacking consistency and a limited traceability of many temporal alignment methods underline the need for standardized and flexible method for the temporal alignment of sclerochronological records here two methods for the temporal alignment of sclerochronological data and their application on measured oxygen isotope signatures of a fish otolith and a marine bivalve shell are presented and compared the first method is a flexible approach using a linear interpolation between carefully selected temporal reference points for recalculating ontogenetic growth effects with an optional extension accounting for seasonal growth oscillations the second approach uses the seasonally oscillating von bertalanffy growth function parameterized based on the oxygen isotope record to reconstruct the underlying growth model and reconstruct thereby its temporal framework using these methods we re align 18 o based water temperature records of a carlarius heudelotii otolith and a venus crebrisulca shell with measured sea surface temperature time series and compare the resulting correlation as well as the different underlying growth models our results show that both methods represent useful tools for the temporal alignment of sclerochronological records however underlying growth models strongly differ depending on the temporal alignment method and the parameters used for the reconstruction of the temporal framework this underlines the importance of a careful selection of a particular alignment method depending on the complexity of distortion due to seasonal and ontogenetic growth trajectories moreover we show that both organisms represent reliable paleoenvironmental archives providing sub seasonally resolved water temperature records

increased seasonality in the western mediterranean during the last glacial from limpet shell geochemistry the seasonal cycle is a fundamental aspect of climate with a significant influence on mean climate and on human societies assessing seasonality in different climate states is therefore important but outside the tropics very few palaeoclimate records with seasonal resolution exist and there are currently no glacial age seasonal resolution sea surface temperature sst records at mid to high latitudes here we show that both mg ca and oxygen isotope 18o ratios in modern limpet patella shells record the seasonal range of sst in the western mediterranean a region particularly susceptible to seasonal change analysis of a suite of fossil limpet shells from gibraltar shows that sst seasonality was greater during the last glacial by 2 c as a result of greater winter cooling these extra tropical seasonal resolution sst records for the last glacial suggest that the presence of large ice sheets in the northern hemisphere enhances winter cooling this result also indicates that seasonality in the mediterranean is not well represented in most palaeoclimate models which typically show little change in seasonal amplitude and provides a new test for the accuracy of climate models

sea surface water temperatures over the period 1884 1983 reconstructed from oxygen isotope ratios of a bivalve mollusk shell arctica islandica southern north sea although climate system modeling cannot be imagined without long sea surface temperature sst records observational data is spatiotemporally incomplete and inhomogeneous prior to about 1950 moreover almost no high resolution sst proxies exist from temperate and boreal marine settings here we present a temporally equidistant high resolution sst proxy record of the southern north sea during the period 1884 1983 calculated from oxygen isotope ratios 18oaragonite of arctica islandica l a bivalve mollusk shell arctica islandica produces daily growth increments which enable precise intraannual dating the growing season of specimens from about 25 m water depth upper well mixed layer of the ocean started in february and ended in september observational coads etc and 18oaragonite derived sst data during february through september compare well to each other especially after 1950 apart from similar overall sst trends we found north atlantic oscillation type cycles of 7 9 years in our proxy sst record and in various different instrumentally determined sst chronologies no vital effects exist so that 18oaragonite ratios determined across the shell i e throughout lifetime of the studied specimen reflect ambient water temperatures that occurred during shell growth results of our study demonstrate that a islandica provides long independent and high resolution sst proxy chronologies from higher latitudes such records can complement and further validate observational sst data and help improving climate system models

new views of tropical paleoclimates from corals abstract corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi decadal climate sensitivity is incomplete in the eastern equatorial pacific coral isotopic records track variations in enso related changes in sea surface temperature further west corals record variability in sea surface temperature and rainfall that accompanies zonal displacement of the indonesian low during enso events these multi century records reveal previously unrecognised enso variability on time scales of decades to centuries outside the enso sensitive equatorial pacific long term trends towards recent warmer wetter conditions suggest the tropics respond to global forcings new coral paleothermometers indicate that surface ocean temperatures in the tropical southwestern pacific were depressed by 4 6 c during the younger dryas climatic event and rose episodically during the next 4000 yr high temporal resolution measurements of sr ca and 18 o in corals provide information about the surface ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation radiocarbon measurements in corals coupled with ocean circulation models may be used to reconstruct near surface ocean circulation past mixing rates and the distribution of fossil fuel co2 in the upper ocean most recently seasonal to interannual variations in the radiocarbon of corals from the equatorial pacific have been linked to the redistribution of surface waters associated with the enso

climate variability over the last 35 000 years recorded in marine and terrestrial archives in the australian region an oz intimate compilation abstract the australian region spans some 60 of latitude and 50 of longitude and displays considerable regional climate variability both today and during the late quaternary a synthesis of marine and terrestrial climate records combining findings from the southern ocean temperate tropical and arid zones identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35 000 years climate drivers include the seasonal timing of insolation greenhouse gas content of the atmosphere sea level rise and ocean and atmospheric circulation changes our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region limiting the usefulness of this approach instead we have taken a spatial approach looking to discern the patterns of change across the continent the data identify the clearest and most synchronous climatic response at the time of the last glacial maximum lgm 21 3 ka with unambiguous cooling recorded in the ocean and evidence of glaciation in the highlands of tropical new guinea southeast australia and tasmania many terrestrial records suggest drier conditions but with the timing of inferred snowmelt and changes to the rainfall runoff relationships driving higher river discharge at the lgm in contrast the deglaciation is a time of considerable south east to north west variation across the region warming was underway in all regions by 17 ka post glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north west of the continent in contrast to the southern latitudes no evidence for cooling during the younger dryas chronozone is evident in the region but the antarctic cold reversal clearly occurs south of australia the holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the holocene giving way to a weakened monsoon and an increasingly el nino dominated enso to the present the influence of enso is evident throughout the southeast of australia but not the southwest this climate history provides a template from which to assess the regionality of climate events across australia and make comparisons beyond our region

coralline algal growth increment widths archive north atlantic climate variability over the past decade coralline algae have increasingly been used as archives of paleoclimate information encrusting coralline algae which deposit annual growth increments in a high mg calcite skeleton are amongst the longest lived shallow marine organisms in fact a live collected plant has recently been shown to have lived for at least 850 years based on radiometric dating while a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures less attention has been paid to employ growth increment widths as a temperature proxy here we explore the relationship between growth and environmental parameters in clathromorphum compactum collected in the subarctic northwestern atlantic results indicate that growth increment widths of individual plants are poorly correlated with instrumental sea surface temperatures sst however an averaged record of multiple growth increment width time series from a regional network of c compactum specimens up to 800 km apart reveals strong correlations with annual instrumental sst since 1950 hence similar to methods applied in dendrochronology averaging of multiple sclerochronological records of coralline algae provides accurate climate information a 115 year growth increment width master chronology created from modern collected and museum specimens is highly correlated to multidecadal variability seen in north atlantic sea surface temperatures positive changes in algal growth anomalies record the well documented regime shift and warming in the northwestern atlantic during the 1990s large positive changes in algal growth anomalies were also present in the 1920s and 1930s indicating that the impact of a concurrent large scale regime shift throughout the north atlantic was more strongly felt in the subarctic northwestern atlantic than previously thought and may have even exceeded the 1990s event with respect to the magnitude of the warming

seasonal temperature variability of the neoglacial 3300 2500 bp and roman warm period 2500 1600 bp reconstructed from oxygen isotope ratios of limpet shells patella vulgata northwest scotland abstract seasonal sea surface temperature variability for the neoglacial 3300 2500 bp and roman warm period rwp 2500 1600 bp which correspond to the bronze and iron ages respectively was estimated using oxygen isotope ratios obtained from high resolution samples micromilled from radiocarbon dated archaeological limpet patella vulgata shells the coldest winter months recorded in neoglacial shells averaged 6 6 0 3 c and the warmest summer months averaged 14 7 0 4 c one neoglacial shell captured a year without a summer which may have resulted from a dust veil from a volcanic eruption in the katla volcanic system in iceland rwp shells record average winter and summer monthly temperatures of 6 3 0 1 c and 13 3 0 3 c respectively these results capture a cooling transition from the neoglacial to rwp which is further supported by earlier studies of pine history in scotland pollen type analyses in northeast scotland and european glacial events the cooling transition observed at the boundary between the neoglacial and rwp in our study also agrees with the abrupt climate deterioration at 2800 2700 bp also referred to as the subboreal subatlantic transition and therefore may have been driven by decreased solar radiation and weakened north atlantic oscillation conditions

marine or estuarine radiocarbon reservoir corrections for mollusks a case study from a medieval site in the south of england abstract mollusk shells are frequently radiocarbon dated and provide reliable calibrated age ranges when the regional marine reservoir correction is well established for mollusks from an estuarine environment the reservoir correction may be significantly different than the regional marine reservoir correction due to the input of bedrock or soil derived carbonates some mollusk species such as oysters are tolerant of a significant range of salinities which makes it difficult to determine which reservoir correction is appropriate a case study is presented of an anomalous radiocarbon age for an oyster shell paint dish found in the fabric of the ruined nave walls of st mary s church shoreham by sea west sussex england stable isotopes 18 o and 13 c were used to establish the type of environment in which the oyster had lived paired marine and terrestrial samples from a nearby medieval site were radiocarbon dated to provide an appropriate reservoir correction

oceanography in northwestern europe during the last interglacial from intrashell δ18o ranges in littorina littorea gastropods abstract coastal sea surface temperature sst and sea surface salinity sss including seasonality in northwest nw europe during the early phase of the eemian interglacial ca 125 ka ago were reconstructed from littorina littorea common periwinkle gastropods the results were based on intra annual 18o analyses in recent and fossil shells mainly originating from the sea of kattegat sweden and the english channel united kingdom and confined to intertidal settings the eemian l littorea shells indicated annual ssts in the range 8 18 c for the english channel and 8 26 c for kattegat all specimens from the eemian sites experienced summer ssts of ca 1 3 c above recent conditions the estimated winter sst in the english channel during the eemian was comparable to modern measurements of ca 8 c however the kattegat region displayed eemian winter sst approximately 8 c warmer than today and similar to conditions in the western english channel the recent fossil isotope analogue approach indicated high sss above 35 practical salinity units psu for a channel south of england in full contact with the north atlantic ocean during the last interglacial in addition the kattegat shells indicated a sss of ca 29 psu which points out a north sea affinity for this region during the eemian

isotope paleontology growth and composition of extant calcareous species abstract isotope paleontology uses the isotopic composition of fossil remains of organisms to make inferences about the physical surroundings of growth of the organisms especially temperature and to obtain clues about life history and modes of growth in calcareous fossils oxygen isotopes are mainly used in the former and carbon isotopes in the latter however since physical surroundings and organism response are intimately associated both types of information are contained in each of the isotopic signals to explore the potential of isotope paleontology and to provide a basis for reconstruction a broad range of extant organisms has been studied taking the pioneering work of epstein and associates as a starting point results are summarized for a representative sampling of these studies with emphasis on work at the laboratories of the authors from the mid seventies to the present the organisms considered are nannoplankton benthic algae planktonic and benthic deep sea foraminifera larger foraminifera sponges corals bryozoans polychaetes arthropods bivalves gastropods cephalopods and vertebrates fish otoliths the survey broadly suggests that regarding oxygen isotopes materials tend to be precipitated close to equilibrium with the surrounding seawater as postulated by urey and that for carbon isotopes disequilibrium is the rule life spans growth rates differential seasonal growth and age of reproductive activity can be extracted under favorable circumstances from individual shells and skeletal parts in detail the interpretation of isotope records of individual shells is quite complicated and simple models will fail to give satisfactory results in many or most cases

high resolution palaeoclimatology of the last millennium a review of current status and future prospects this review of late holocene palaeoclimatology represents the results from a pages clivar intersection panel meeting that took place in june 2006 the review is in three parts the principal high resolution proxy disciplines trees corals ice cores and documentary evidence emphasizing current issues in their use for climate reconstruction the various approaches that have been adopted to combine multiple climate proxy records to provide estimates of past annual to decadal timescale northern hemisphere surface temperatures and other climate variables such as large scale circulation indices and the forcing histories used in climate model simulations of the past millennium we discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo proxies derived from climate model runs where the answer is known the article concludes with a list of recommendations first more raw proxy data are required from the diverse disciplines and from more locations as well as replication for all proxy sources of the basic raw measurements to improve absolute dating and to better distinguish the proxy climate signal from noise second more effort is required to improve the understanding of what individual proxies respond to supported by more site measurements and process studies these activities should also be mindful of the correlation structure of instrumental data indicating which adjacent proxy records ought to be in agreement and which not third large scale climate reconstructions should be attempted using a wide variety of techniques emphasizing those for which quantified errors can be estimated at specified timescales fourth a greater use of climate model simulations is needed to guide the choice of reconstruction techniques the pseudo proxy concept and possibly help determine where given limited resources future sampling should be concentrated

the ksâr akil lebanon mollusc assemblage zooarchaeological and taphonomic investigations abstract shells of marine molluscs exploited by prehistoric humans constitute archives of palaeoecological and palaeoclimatic data as well as of human behaviour in coastal settings here we present our investigations on the mollusc assemblage from ks r akil lebanon a key site in southwestern asia occupied during the middle and upper palaeolithic the site plays an important role in understanding modern human dispersals into eurasia taxa from intertidal rocky shore subtidal soft bottom and rocky littoral habitats dominate the marine component of the invertebrate assemblage terrestrial snails indicate wooded and open half shaded habitats in the vicinity of the site species composition suggests that these habitats were present throughout the upper palaeolithic humans transported marine molluscs to the rockshelter as food packages for dietary purposes e g patella caerulea patella rustica phorcus turbinatus and shells of other taxa to be used as tools e g glycymeris sp or possibly for ornamental purposes e g nassarius gibbosulus and columbella rustica in the initial upper palaeolithic collection focussed on empty shells as raw material for utilitarian purposes in the subsequent early upper palaeolithic and later periods mollusc gathering was performed in an increasing number of habitats and shifted towards collection for human consumption which was the main reason for the introduction of shells to the site during the epipalaeolithic concurrent size shifts of live collected as well as beached specimens suggests that size changes were linked to environmental change rather than to potential overexploitation of dietary taxa by humans

accurate increment identification and the spatial extent of the common signal in five arctica islandica chronologies from the fladen ground northern north sea 1 the creation of networks of shell based chronologies which can provide regionally extensive high resolution proxies for the marine environment depends on the spatial extent of the common environmental signal preserved in the shell banding and on the reliability of the dating model here arctica islandica chronologies from five neighboring sites in the north sea are compared and the strength of the common environmental signal across distances up to 80 km is analyzed using statistical techniques derived from dendrochronology the signal is found to be coherent across these distances in a linked study chronologies based on one of the same sites but constructed by two different research teams are compared methodological differences in increment interpretation are found to lead to slippage in the dating models systematic inclusion or exclusion of intermittently occurring increments results in the two chronologies becoming misaligned by 4 years over a 70 year period comparisons with neighboring chronologies indicate that such increments can generally be regarded as genuine annual increments even if they are not visible in all shells

a review of sea ice proxy information from polar ice cores sea ice plays an important role in earth s climate system the lack of direct indications of past sea ice coverage however means that there is limited knowledge of the sensitivity and rate at which sea ice dynamics are involved in amplifying climate changes as such there is a need to develop new proxy records for reconstructing past sea ice conditions here we review the advances that have been made in using chemical tracers preserved in ice cores to determine past changes in sea ice cover around antarctica ice core records of sea salt concentration show promise for revealing patterns of sea ice extent particularly over glacial interglacial time scales in the coldest climates however the sea salt signal appears to lose sensitivity and further work is required to determine how this proxy can be developed into a quantitative sea ice indicator methane sulphonic acid msa in near coastal ice cores has been used to reconstruct quantified changes and interannual variability in sea ice extent over shorter time scales spanning the last 160 years and has potential to be extended to produce records of antarctic sea ice changes throughout the holocene however the msa ice core proxy also requires careful site assessment and interpretation alongside other palaeoclimate indicators to ensure reconstructions are not biased by non sea ice factors and we summarise some recommended strategies for the further development of sea ice histories from ice core msa for both proxies the limited information about the production and transfer of chemical markers from the sea ice zone to the antarctic ice sheets remains an issue that requires further multidisciplinary study despite some exploratory and statistical work the application of either proxy as an indicator of sea ice change in the arctic also remains largely unknown as information about these new ice core proxies builds so too does the potential to develop a more comprehensive understanding of past changes in sea ice and its role in both long and short term climate changes

stable isotope fractionation between mollusc shells and marine waters from martinique island abstract forty nine aragonitic and calcitic shells from 14 species of marine tropical molluscs bivalvia gastropoda polyplacophora and ambient waters from martinique have been analyzed for their carbon and oxygen isotope compositions mineralogy of shells was systematically determined by raman spectroscopy that reveals composite shell structures and early processes of diagenetic alteration in mangrove brackish waters result from the mixing between 89 1 of seawater and 11 1 of freshwater a hydrological budget quantified by both oxygen isotope and salinity mass balance calculations mollusc shells from the mangrove environment s 31 18 o 0 5 are characterized by mean 13 c values 1 2 lower than those 2 6 living in the open sea s 35 18 o 1 these low carbon isotope compositions result from the oxidation of organic matter into bicarbonate ions used in the building of mollusc shells the oxygen isotope compositions of the studied mollusc species are mainly controlled by the temperature and composition of seawater whereas the role of the so called vital effects is negligible contrasting with carbon isotopes variability in the 18 o values among and within species of mollusc shells is very low 1 0 15 for a given littoral environment using ambient temperatures of seawater 28 30 c oxygen isotope fractionations between all studied living species and environmental waters match those extrapolated from the fractionation equation established for molluscs by grossman and ku chem geol isot geosci sect 59 1986 59 in the range 3 20 c by analyzing calcite and aragonite layers from the same shell or by comparing shells from different species living in the same environment there is no evidence that oxygen isotope fractionation between aragonite and water differs from that between calcite and water on the basis of these results we conclude that the oxygen isotope compositions of shells from most fossil mollusc species are suitable to estimate past seawater temperatures at any paleolatitude

sclerochronology and geochemical variation in limpet shells patella vulgata a new archive to reconstruct coastal sea surface temperature 1 climate archives contained in shells of the european limpet patella vulgata accumulated in archaeological deposits can potentially provide much needed information about holocene environmental change in midlatitude coastal areas before reconstructing climate information preserved in these zooarchaeological records we studied the controls on oxygen and carbon isotope ratios 18o and 13c respectively in modern specimens we tested the hypothesis that p vulgata precipitates its shell in isotopic equilibrium with the ambient water by comparing 18oshell with predicted values predicted 18oshell was constructed using observed sea surface temperature sst records and the equilibrium fractionation equation for calcite and water we assumed a constant 18owater value of 0 10 vsmow based on published regional measurements comparison of 18oshell with predicted values revealed that 18oshell values were higher than expected by 1 01 0 21 consequently estimated sst calculated from 18oshell was 4 2 2 3 c lower than observed sst however because of the relatively uniform offset between observed and expected 18o an adjustment can be made to account for this predictable vital effect thus past climate can be reliably reconstructed using this temperature proxy once the offset is taken into account 13c values have a similar cyclicity to the 18o variation and therefore vary seasonally however 13c is slightly out of phase relative to 18o an overall negative shift in 13cshell over the lifetime of the individual indicates a vital effect associated with ontogeny further study of environmental and ecological factors that influence shell 13c is required to evaluate fully the potential of carbon isotope ratios as a useful environmental proxy

high resolution analysis of trace elements in crustose coralline algae from the north atlantic and north pacific by laser ablation icp ms we have investigated the trace elemental composition in the skeleta of two specimens of attached living coralline algae of the species clathromorphum compactum from the north atlantic newfoundland and clathromorphum nereostratum from the north pacific bering sea region amchitka island aleutians samples were analyzed using laser ablation inductively coupled plasma mass spectrometry la icp ms yielding for the first time continuous individual trace elemental records of up to 69 years in length the resulting algal mg ca sr ca u ca and ba ca ratios are reproducible within individual sample specimens algal mg ca ratios were additionally validated by electron microprobe analyses amchitka sample algal sr ca u ca and ba ca ratios were compared to algal mg ca ratios which previously have been shown to reliably record sea surface temperature sst ratios of sr ca from both clathromorphum species show a strong positive correlation to temperature dependent mg ca ratios implying that seawater temperature plays an important role in the incorporation of sr into algal calcite linear sr ca sst regressions have provided positive but weaker relationships as compared to mg ca sst relationships both algal mg ca and sr ca display clear seasonal cycles inverse correlations were found between algal mg ca and u ca ba ca and correlations to sst are weaker than between mg ca sr ca and sst this suggests that the incorporation of u and ba is influenced by other factors aside from temperature

new research on the development of high resolution palaeoenvironmental proxies from geochemical properties of biogenic carbonates abstract geochemical signatures from biogenic carbonates are being increasingly employed as palaeoenvironmental proxies in turn many of these proxy archives including mollusc shells corals and otoliths have periodic growth structures which allow the reconstruction of chronologically constrained records of palaeoenvironmental variability at unparalleled high temporal resolution studying the growth and chemistry of these periodic growth structures is known as sclerochronology biogenic hard parts accumulate in geological or archaeological deposits and can be directly dated using radiometric and racemisation methods they therefore offer the opportunity for high resolution palaeoenvironmental reconstructions across many time intervals all over the globe such data are important for several reasons 1 understanding past climate and environmental change provides a means of contextualising current and future climate change and ecological disturbance 2 high resolution palaeoenvironmental records are essential for constraining testing and validating global and regional numerical climate models 3 palaeoenvironmental records from biogenic carbonates can provide an environmental framework from which to understand the behavioural changes and interactions of peoples with their environment however inter and intra species differences in growth rate physiology and environmental response can cause variations in the chemical profiles of biogenic carbonates before geochemical data is employed for palaeoenvironmental reconstructions it is thus necessary to examine modern specimens of the target species or related taxa to understand how geochemical variations are influenced by local environmental conditions kinetic and vital effects this allows the generation of quantitative and more reliable proxy records of environmental change this special issue brings together the latest research on palaeoenvironmental proxy development and validation in biogenic carbonates it includes studies on marine freshwater and estuarine organisms molluscs corals and echinoderms and on traditional as well as novel geochemical proxies the papers presented here include in situ field calibration studies laboratory growth experiments as well as methodological studies into the effects of sampling and pre treatment the geographical scope is broad encompassing both the northern and southern hemispheres including south africa south america australia asia the mediterranean sea and the north atlantic

shell morphometry of seven limpet species from coastal shell middens in southern africa measurements of shell parts and features elements of marine limpets can be used to derive morphometric equations for estimating total shell lengths this is demonstrated for seven limpet species commonly found on the southern african coast the equations can be used to reconstruct whole shell lengths for highly fragmented limpet samples in prehistoric shell middens a linear regression model is based on measurements of all shell elements resulting in high coefficients of determination with excellent predictive power in most cases these morphometric equations would enable archaeologists to derive more metrical information from fragmentary archaeological material than was previously the case we also present a case study where morphometric equations of two limpet species are applied to an archaeological sample from the south african west coast for the purpose of investigating possible biases in limpet shell preservation we conclude that small whole limpet shells survive longer than the bigger ones in this particular case but that many more such case studies need to be conducted in order to fully understand differential preservation of southern african limpet shells in archaeological sites

multi proxy reconstructions of northeastern pacific sea surface temperature data from trees and pacific geoduck abstract we demonstrate the potential for developing sea surface temperature sst reconstructions in the northeast pacific from combinations of tree ring and growth increment chronologies of the long lived marine bivalve the pacific geoduck six pacific geoduck chronologies developed from site along the washington british columbia coast are compared and combined with tree ring chronologies from california to alaska all chronologies are annually resolved and strongly relate to local to regional scale sst though differences in the response season as well as the spectral properties of the two proxies are observed both proxy types closely track sst and when used in combination yield a more robust sst reconstruction than tree ring or geoduck chronologies could provide alone in total variance explained in sst is 63 9 at the regional scale and 68 2 at a local scale providing sst estimates for more than 60 years prior to the start of continuous instrumental records in this region this study represents one of the few climate reconstructions where both proxies are annually resolved and is the first to integrate regional networks of geoduck chronologies and tree ring chronologies

seasonal climate signals 1990 2008 in a modern soreq cave stalagmite as revealed by high resolution geochemical analysis article high resolution isotopic and geochemical analyses in a modern 1990 2008 soreq cave stalagmite are com pared to instrumental records of rainfall and dripwater from the cave with the aim of determining how seasonal resolutionclimateinformationistransmittedtospeleothemgeochemistry insitu micron scaleanalysis of oxygen isotope ratios 18 o and trace elements by ion microprobe in combination with a continuous linear traverse of trace element concentrations by laser ablation icp ms la icp ms allow the definition of geochem ical pathways within the cave fluorescent banding imaged by confocal laser fluorescent microscopy clfm as well as

changing patterns of eastern mediterranean shellfish exploitation in the late glacial and early holocene oxygen isotope evidence from gastropod in epipaleolithic to neolithic human occupation layers at the haua fteah cave libya abstract the seasonal pattern of shellfish foraging at the archaeological site of haua fteah in the gebel akhdar libya was investigated from the epipaleolithic to the neolithic via oxygen isotope 18 o analyses of the topshell phorcus osilinus turbinatus to validate this species as faithful year round palaeoenvironmental recorder the intra annual variability of 18 o in modern shells and sea water was analysed and compared with measured sea surface temperature sst the shells were found to be good candidates for seasonal shellfish forging studies as they preserve nearly the complete annual sst cycle in their shell 18 o with minimal slowing or stoppage of growth during the terminal pleistocene early epipaleolithic locally known as the oranian with modeled dates of 17 2 12 5 ka at 2 probability douka et al 2014 analysis of archaeological specimens indicates that shellfish were foraged year round this complements other evidence from the archaeological record that shows that the cave was more intensively occupied in this period than before or afterwards this finding is significant as the period of the oranian was the coldest and driest phase of the last glacial cycle in the gebel akhdar adding weight to the theory that the gebel akhdar may have served as a refugium for humans in north africa during times of global climatic extremes mollusc exploitation in the latest pleistocene and early holocene during the late epipaleolithic locally known as the capsian c 12 7 to 9 ka and the neolithic c 8 5 to 5 4 ka occurred predominantly during winter other evidence from these archaeological phases shows that hunting activities occurred during the warmer months therefore the timing of holocene shellfish exploitation in the gebel akhdar may have been influenced by the seasonal availability of other resources at these times and possibly shellfish were used as a dietary supplement when other foods were less abundant

impact of atmospheric p co 2 seawater temperature and calcification rate on the δ 18 o and δ 13 c composition of echinoid calcite echinometra viridis the tropical echinoid echinometra viridis was reared in controlled laboratory experiments at temperatures of approximately 20 c and 30 c to mimic winter and summer temperatures and at carbon dioxide co2 partial pressures of approximately 487 ppm v and 805 ppm v to simulate current and predicted end of century levels spine material produced during the experimental period and dissolved inorganic carbon dic of the corresponding culture solutions were then analyzed for stable oxygen 18oe 18odic and carbon 13ce 13cdic isotopic composition fractionation of oxygen stable isotopes between the echinoid spines and dic of their corresponding culture solutions 18o 18oe 18odic was significantly inversely correlated with seawater temperature but not significantly correlated with atmospheric pco2 fractionation of carbon stable isotopes between the echinoid spines and dic of their corresponding culture solutions 13c 13ce 13cdic was significantly positively correlated with pco2 and significantly inversely correlated with temperature with pco2 functioning as the primary factor and temperature moderating the pco2 13c relationship echinoid calcification rate was significantly inversely correlated with both 18o and 13c across treatments with effects of pco2 and temperature controlled for through anova therefore calcification rate and potentially the rate of co occurring dissolution appear to be important drivers of the kinetic isotope effects observed in the echinoid spines study results suggest that echinoid 18o monitors seawater temperature but not atmospheric pco2 and that echinoid 13c monitors atmospheric pco2 with temperature moderating this relationship these findings coupled with echinoids long and generally high quality fossil record support prior assertions that fossil echinoid 18o is a viable archive of paleo seawater temperature throughout phanerozoic time and that 13c merits further investigation as a potential proxy of paleo atmospheric pco2 however the apparent impact of calcification rate on echinoid 18o and 13c suggests that paleoceanographic reconstructions derived from these proxies in fossil echinoids could be improved by incorporating the effects of growth rate

unraveling environmental histories from skeletal diaries advances in sclerochronology high resolution proxy archives from aquatic settings are essential to better understand processes and mechanisms of global change during the last decade it has become increasingly evident that calcified tissues of bivalve mollusks and cold water corals in particular can significantly increase our knowledge of seasonal to multi decadal paleoclimate and paleoenvironmental variability in the extratropical oceans and coastal marine settings daily tidal fortnightly and annual growth patterns of periodically formed skeletal hard parts provide a means to place the proxy record in a precise temporal context their extreme longevity coupled with the running similarity between growth increment time series of contemporaneous bivalves opens the possibility of constructing stacked chronologies covering centuries to millennia which provide information on decadal climate and environmental variability and magnitudes of climate variability through time a current major research focus is on how to translate geochemical properties of the skeletons into quantifiable environmental proxy data and how to eliminate the adverse influence of vital effects on the proxy records this special issue presents the most recent advances in the field of sclerochronology specifically calcified tissues of bivalve mollusks cold water corals and tropical shallow water corals the majority of the contributions deal with the potential reconstruction of temperature ph and productivity through the analysis of variable growth rates sr ca mg ca ba ca u ca li ca 13c 18o and 44 40ca four papers present composite chronologies of two long lived bivalve species and discuss inherent decadal climate variability and one study demonstrates that sclerochronology can shed light on socioeconomic patterns of past human populations as well as resource use and resource management by people

a late pleistocene refugium in mediterranean north africa palaeoenvironmental reconstruction from stable isotope analyses of land snail shells haua fteah libya abstract the late pleistocene to holocene archaeological record of north africa is key to understanding the emergence of anatomically modern humans into west asia and europe and the broadening of subsistence strategies in the shift from hunter gatherer to pastoral agricultural lifeways some contend that these developments were modulated by major shifts in climate and environment evaluation of this hypothesis requires the pairing of local and regional climate records with well dated archaeological sequences the haua fteah archaeological site in the gebel akhdar region of libya provides a key site to test this hypothesis as the cave contains one of the longest and most complete sequences of human occupation in north africa as well as abundant material for palaeoenvironmental reconstruction this study uses stable isotope analyses 18o and 13c of the terrestrial mollusc helix melanostoma to construct a palaeoenvironmental framework for interpreting north african human environment interactions from the upper palaeolithic to the neolithic 30 000 to 5000 years ago the land snail stable isotope records from haua fteah suggests that cool arid conditions in the cave peaked during marine isotope stage mis 2 this stage was however only marginally drier than previous and subsequent stages and coincided with an increase in occupation density in the cave this suggests that the gebel akhdar may have served as an environmental refugium from the more extreme aridity in the surrounding sahara and arid coastal plains for late stone age lsa populations in north africa conditions became progressively wetter towards the holocene however generally wetter conditions were interrupted by two arid episodes at c 8 0 ka and 7 3 ka that appear to coincide with regional changes reflected elsewhere in the mediterranean basin

reassessing the 2006 guerrero slow slip event mexico implications for large earthquakes in the guerrero gap in guerrero mexico slow slip events have been observed in a seismic gap where no earthquakes have occurred since 1911 a rupture of the entire gap today could result in a mw 8 2 8 4 earthquake however it remains unclear how slow slip events change the stress field in the guerrero seismic region and what their implications are for devastating earthquakes most earlier studies have relied on a sparse network of global navigation satellite systems measurements here we show that interferometric synthetic aperture radar can be used to improve the spatial resolution we find that slip due to the 2006 slow slip event enters the seismogenic zone and the guerrero gap with 5 cm slip reaching depths as shallow as 12 km we show that slow slip is correlated with a highly coupled region and estimate that slow slip events have decreased the total accumulated moment since the end of the 2001 2002 slow slip event 4 7 years by 50 nevertheless even accounting for slow slip the moment deficit in the guerrero gap increases each year by mw 6 8 the guerrero gap therefore still has the potential for a large earthquake with a slip deficit equivalent to mw 8 15 accumulated over the last century correlation between the slow slip region and nonvolcanic tremor and between slow slip and an ultraslow velocity layer supports the hypothesis of a common source potentially related to high pore pressures

shell midden sclerochronology abstract sclerochronological analysis of shell midden faunal remains offers a unique opportunity to study climate and environmental change in relation to human activity middens exist near most aquatic habitats almost worldwide for much of the late pleistocene and holocene they afford good preservation of accretionary calcium carbonate remains such as mollusk shells and fish otoliths in comparatively well dated contexts as such midden samples are a source of sequential proxy records of past climate and environmental conditions and may provide detailed pictures of human environment interaction however midden samples present several challenges to the development and application of sclerochronological proxies including unique taphonomic concerns here these challenges are outlined within descriptions of the major applications of midden sclerochronology archeological concerns including season of capture reconstructing the history of anthropogenic environmental impacts and paleoclimate environment proxy reconstructions

paleoenvironmental proxies in echinoid spines eucidaris galapagensis doderlein 1887 along a natural water temperature gradient abstract the use of paleoenvironmental proxies such as oxygen isotopes in echinoderm skeletons has been a matter of controversial debate many previous studies showed a variety of environmental as well as biological processes causing deviations from equilibrium incorporation of geochemical proxies during the formation of echinoderm skeletons however given the global distribution of echinoids their fast spine growth and their occurrence throughout the entire phanerozoic species specific calibrations of geochemical proxies in echinoid spines can disclose a valuable bio archive for reconstructing ancient environmental conditions throughout earth s history if samples are adequately preserved in the sedimentary record here we present data on oxygen isotopes 18 o carbon isotopes 13 c and mg ca ratios measured in eucidaris galapagensis doderlein 1887 spines which were sampled along the natural water temperature gradient of the galapagos archipelago we found a negative correlation of 18 o calcite with ambient water temperature following the equation 1000 ln 23 03 10 3 t 1 k 47 90 we also found 13 c calcite be positively correlated with water temperature following the equation 13 c calcite vpdb 47 585 0 164 t k mg ca ratios also showed a significant correlation with water temperature however with a low correlation coefficient the large scatter of 18 o calcite values within the upwelling region indicates higher growth rates during seasons of colder water temperatures considering this and the observed steeper slope in the temperature 18 o calcite relationship our data suggest that the common assumption of respiration affecting oxygen isotope fractionation does not apply for the tropical species e galapagensis overall our data show that e galapagensis spines represent valuable paleoenvironmental archives which might have the potential to provide sub annually resolved water temperature records if spine architecture and growth pattern are well constrained

u series and radiocarbon dates on mollusc shells from the uppermost layer of the archaeological site of khb 1 ra s al khabbah oman the archaeological site of khb 1 oman has been investigated in order to improve the chronological knowledge of the site which is dated to the beginning of the fourth millennium b c on the basis of the archaeological context mollusc shells of the genus anadara coming from the uppermost layers of the site have been dated using two different methods radiocarbon and u series technique the results of the two techniques date the last occupational phase of the site from the end of the fourth millennium b c to the beginning of the third millennium b c

north atlantic oscillation dynamics recorded in shells of a long lived bivalve mollusk existing reconstructions of the winter north atlantic oscillation wnao are based on terrestrial proxies and historical documents no direct high resolution long term rec ords from marine settings are available for this major climate dictating phenomenon which severely affects a variety of economic aspects of our society here we present a 245 yr proxy wnao index based on shells of the long lived marine bivalve mollusk arctica islandica variations in annual rates of shell growth are positively correlated with wnao related changes in the food supply maximum amplitudes in frequency bands of 7 9 and 5 7 yr fall exactly within the range of instrumental and other proxy wnao indices these estimates were obtained for specimens collected live 2000 km apart in the central north sea and on the norwegian shelf hence the wnao influences hydrographic regimes of large regions of the ocean our study demonstrates that a islandica can reliably reconstruct wnao dynamics for time intervals and regions without instrumental records our new tool functions as a proxy for the wnao index prior to the twentieth century greenhouse forcing and has the potential to further validate other proxy based wnao records

astronomical dating of a tectonic rotation on sicily and consequences for the timing and extent of a middle pliocene deformation phase a detailed palaeomagnetic study of long and continuous middle pliocene sections from the caltanisetta basin on sicily reveals a differential clockwise rotation occurring around 3 21 ma the rotation appears to be a rapid event 80 000 100 000 years which suggests that the responsible tectonic processes also occur rapidly its timing corresponds closely to the transition from the trubi to the narbone formation at 3 19 ma this transition marks a major change in sedimentary environment on sicily and in calabria and it is coeval for instance with the onset of sapropel formation in the eastern mediterranean apparently it marks a synchronous and central eastern mediterranean wide event data from the oldest sediments overlying the tyrrhenian basement odp leg 107 suggest an acceleration in opening of the tyrrhenian sea during the middle pliocene we speculate that this acceleration is related to a transpressional event in the sicilian fold and thrust belt and extension which formed troughs in the foreland the strait of sicily thrust imbrication accompanying the transpressional event on sicily induced the middle pliocene clockwise rotation and resulted in shallowing of the caltanisetta basin causing the change in sedimentation regime characterised by the trubi narbone transition following this middle pliocene tectonic phase no rotation took place in the southern apennines calabria and sicily until the middle pleistocene 1 0 0 7 ma 1998 elsevier science b v all rights reserved

the role of seasonality in abrupt climate change abstract a case is made that seasonality switches dominated by wintertime were instrumental in abrupt climate changes in the north atlantic region during the last glaciation and into the holocene the primary evidence comes from mismatches between mean annual temperatures from greenland ice cores in comparison with snowline changes in east greenland northern europe and north america the most likely explanation is a shutdown or reduction in strength of the conveyor this allows the spread of winter sea ice across the north atlantic thus causing the northern region to experience much colder winters because they mimic the greenland temperature rather than the snowline signal changes in the atlantic intertropical convergence zone and the asian monsoon may also share a winter linkage with greenland thus the paleoclimate record is consistent with the notion that a huge continental sector of the northern hemisphere stretching from greenland to asia was close to an extreme winter threshold during much of the last glaciation winter climate crossed this threshold repeatedly with marked changes in seasonality that may well have amplified and propagated a signal of abrupt change throughout the hemisphere and into the tropics

changes of shell microstructural characteristics of cerastoderma edule bivalvia a novel proxy for water temperature abstract shells of bivalves potentially provide an excellent archive for high resolution paleoclimate studies however quantification of environmental variables specifically water temperature remains a very challenging task here we explore the possibility to infer water temperature from changes of microstructural characteristics of shells of the common cockle cerastoderma edule the size and elongation of individual microstructural units i e prisms in the outer shell layer of seven three to five year old specimens collected alive from the intertidal zone of the north sea near texel the netherlands and schillig germany were measured by means of automatic image processing growth patterns circatidal ciralunidian and fortnightly increments and lines shell oxygen isotope values and mark and recovery experiments were used to place the shell record in a precise temporal context irrespective of the locality and ontogenetic age size and elongation of the prisms increased non linearly with water temperature small 0 12 0 05 m 2 and round prisms elongation 2 42 0 31 were formed at temperatures of ca 10 c late april whereas larger 0 33 0 11 m 2 and more elongated prisms 3 26 0 28 occurred during hot summer ca 22 c no clear cut or consistent correlation existed between microstructural characteristics and growth rate as well as a variety of other environmental variables such as salinity chlorophyll a and turbidity based on these findings a model was constructed from three shells at texel that enables reconstruction of water temperature with a precision of 1 7 1 0 c from prism size and elongation sst 9 02 17 25 p s 1 10 p e this model was successfully tested at four shells from schillig the new temperature proxy can be of particular interest for paleoclimate studies in nearshore settings when non recrystallized c edule shells are available future studies are required to verify our findings and check if other species with the same and different microstructures show similar relationships with water temperature