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

an evaluation of lohmann s foraminifera weight dissolution index down water column traverses of core top weights for three planktonic species confirm lohmann s 1995 relationship between foraminifera shell weight loss and bottom water carbonate ion content however they also suggest that the initial shell thickness varies with growth habitat and that the offset between bottom water and pore water carbonate ion concentration varies even on small space scales

distribution of magnesium in coral skeleton ion micro probe imaging of the aragonite skeleton of pavona clavus a massive reef building coral shows that magnesium and strontium are distributed very differently in contrast to strontium the distribution of magnesium is strongly correlated with the fine scale structure of the skeleton and corresponds to the layered organization of aragonite fibers surrounding the centers of calcification which have up to ten times higher magnesium concentration this indicates a strong biological control over the magnesium composition of all structural components within the skeleton magnesium may be used by the coral to actively control the growth of the different skeletal crystal components

micro computed tomography applications for high resolution skeletal density determinations an example using annually banded crustose coralline algae warming and acidification of the world s oceans are expected to have widespread consequences for marine biodiversity and ecosystem functioning however due to the relatively short record of instrumental observations one has to rely upon geochemical and physical proxy information stored in biomineralized shells and skeletons of calcareous marine organisms as in situ recorders of past environments of particular interest is the response of marine calcifiers to ocean acidification through the examination of structural growth characteristics here we demonstrate the application of micro computed tomography micro ct for three dimensional visualization and analysis of growth skeletal density and calcification in a slow growing annually banded crustose coralline alga clathromorphum nereostratum increment width 380 m x ray images and time series of skeletal density were generated at 20 m resolution and rebinned to 40 60 80 and 100 m for comparison in a sensitivity analysis calcification rates were subsequently calculated as the product of density and growth linear extension while both skeletal density and calcification rates do not significantly differ at varying spatial resolutions the latter being strongly influenced by growth rates clear visualization of micron scale growth features and the quantification of structural changes on subannual timescales requires higher scanning resolutions in the present study imaging at 20 m resolution reveals seasonal cycles in density that correspond to summer winter variations in skeletal structure observed using scanning electron microscopy sem micro ct is a fast non destructive and high resolution technique for structural and morphometric analyses of temporally banded paleoclimate archives particularly those that exhibit slow or compressed growth or micron scale structures

a simple evaluation of cleaning procedures on fossil benthic foraminiferal mg ca 1 recent studies suggest that benthic foraminiferal mg ca may be useful in reconstructing deep water temperature changes during the quaternary and on longer timescales rosenthal et al 1997 lear et al 2000 martin et al 2002 because changes in deep water temperature may be small sample preparation could play an important role in reconstructing accurate temperatures from shell mg ca a simple examination of changes in measured shell chemistry of benthic foraminifera from two intervals subjected to increasingly rigorous cleaning reveals that fossil benthic foraminiferal samples cleaned by oxidation yield lower mg ca values than samples only rinsed and weak acid leached reductive cleaning further lowered the shell mg ca of one of the two benthic species examined lower mg ca values following oxidation and reduction appear to reflect removal of contaminant mg associated with remnant organic matter and adsorbed phases

microdistribution of mg ca sr ca and ba ca ratios in pulleniatina obliquiloculata test by using a nanosims implication for the vital effect mechanism the mg ca ratio within foraminiferal calcareous tests shells is widely used to reconstruct past seawater temperature however recent studies reported that the organic components within a test affect the mg ca distribution in this study we have measured the mg ca sr ca and ba ca ratios within the planktonic foraminifera pulleniatina obliquiloculata by using a nanosims secondary ion mass spectrometer sims which has excellent spatial resolution 1 m and allows us to compare the distribution of chemical compositions with that of the organic components element compositions show banding distributions composed of alternately higher and lower values of those elemental ratios the mg ca ratios previously considered to be mainly controlled by calcification temperature show larger variations than the values expected from the seawater temperature at the habitat depth of p obliquiloculata comparison of the elemental distribution with the test microstructure reveals that the bands of high mg ca and sr ca ratios correspond with layers of the organic components such coincidence suggests that the organic components strongly affect the mg ca and sr ca ratios within a test in spite of the heterogeneous distribution temperature estimated from the averaged mg ca ratio within a test is consistent with seawater temperature at the habitat depth of p obliquiloculata indicating that whole mg ca ratio of foraminiferal test may be useful as paleotemperature proxy in contrast to the mg ca ratio the heterogenity in ba ca ratio which previously has been considered to be mainly controlled by the ambient seawater composition is not fully matched with the layers of the organic compositions although the organic components concentrate ba other unknown factors appear to also cause heterogenity in ba incorporation

intratest oxygen isotope variability in the planktonic foraminifer n pachyderma real vs apparent vital effects by ion microprobe abstract intratest oxygen isotope variations in the planktonic foraminifer neogloboquadrina pachyderma sinistral left coiling from north atlantic core top and multi net samples were assessed by ion microprobe analysis from 2 to 6 m spots with precision and accuracy better than 0 7 in 18 o 2 sd within a single foraminiferal test from a core top sample comprising both ontogenetic calcite and outer crust 18 o values vary from 0 5 to 3 7 pdb exceeding the range of equilibrium 18 o in the specimens habitat by a factor of three the isotopic difference between the ontogenetic calcite and the crust averages 1 8 neither of the two types of foraminiferal calcite precipitates in equilibrium with ambient seawater the ontogenetic calcite exhibits a negative vital effect 18 o m e 18 o measured 18 o equilibrium ranging from 0 5 to 1 the largest negative fractionation is associated to the inner walls of juvenile chambers in contrast a positive vital effect of about 0 8 was observed in the crust with respect to the highest equilibrium 18 o values at water depths below 200 m hence two vital effects that are opposite in sign are effective within a single foraminiferal test indicating that whole test values of this species are highly sensitive to the degree of encrustation and amplify or attenuate environmental signals the negative vital effect of the ontogenetic calcite was verified by ion microprobe analysis of four nonencrusted net sampled specimens reflecting three different depth intervals intra ontogenetic oxygen isotope ratios in these juvenile tests range from 0 6 to 3 0 and exhibit a negative vital effect even larger than that observed in core top samples based on these data the large range of apparent vital effects reported for this foraminiferal species can be assessed by a mass balance calculation assuming that the degree of encrustation is variable

planktic foraminiferal sedimentation and the marine calcite budget 1 the vertical flux and sedimentation rate of planktic foraminiferal tests are quantified and a global planktic foraminiferal cac0 3 budget is presented test and calcite flux rates are calculated according to the distribution of species obtained from multinet and sediment trap samples modern planktic foraminiferal population dynamics are discussed as a prerequisite for the quantification of the calcite budget highlighting the importance of ecological autecological e g reproduction and biogeochemical conditions that determine the presence or absence of species to complete the open marine particulate caco 3 inventory the contribution of coccolithophores pteropods and calcareous dinophytes is discussed based on the studied regions the global planktic foraminiferal calcite flux rate at 100 m depth amounts to 1 3 3 2 gt yr 1 equivalent to 23 56 of the total open marine caco 3 flux the preservation of tests varies on a regional and temporal scale and is affected by local hydrography and dissolution during most of the year off peak periods many tests dissolve above 700 m water depth while settling through the water column with on average only 1 3 of the initially exported caco 3 reaching the deep seafloor pulsed flux events mass dumps of fast settling particles yield a major contribution of tests to the formation of deep sea sediments on average 25 of the initially produced planktic foraminiferal test cac0 3 settles on the seafloor the total planktic foraminiferal contribution of caco 3 to global surface sediments amounts to 0 36 0 88 gt yr 1 32 80 of the total deep marine calcite budget

linkages between surface and deep circulations in the southern japan sea during the last 27 000 years evidence from planktic foraminiferal assemblages and stable isotope records abstract we analyzed planktic foraminiferal assemblages oxygen and carbon isotope records and the presence or absence of laminations to reconstruct the paleoenvironments of the southern japan sea since the last glacial period data were collected from two well dated cores one core water depth 999 m included thinly laminated mud layers the other water depth 283 m contained nonlaminated sediments tephrochronology and accelerator mass spectrometry 14 c dating of 14 horizons revealed that the two cores contained continuous records of the last 27 cal kyr a total of 13 planktic foraminiferal species belonging to six genera were identified in down core samples the typical indicators of the tsushima current water globigerinoides ruber neogloboquadrina dutertrei pulleniatina obliquiloculata globigerinoides tenellus and globigerinita glutinata occurred since 9 3 cal kyr bp neogloboquadrina incompta which was the dominant species in the tsushima current region of the modern japan sea first occurred at 8 2 cal kyr bp and dominated the assemblage since 7 3 cal kyr bp these results clearly indicate that the warm tsushima current started to inflow into the japan sea at 9 3 cal kyr bp and the modern surface conditions in the southern japan sea were essentially established at 7 3 cal kyr bp our data and comparison of the presence or absence of laminated sediments in three locations from the southern japan sea suggest that deep circulation during the deglacial period was weaker than that at present in addition deep circulation in the modern japan sea which supplies oxygen rich water to the entire basin started probably in association with the first inflow of the tsushima current beginning at 9 3 cal kyr bp

nonlinear internal waves in the south china sea observation of the conversion of depression internal waves to elevation internal waves 1 the conversion of depression nonlinear internal solitons to elevation internal waves has been observed twice at the south china sea continental shelf break shipboard x band radar tow yo ctd adcp and high frequency acoustic flow visualization of the process are presented the data focuses on up slope propagation of depression internal solitons from a water depth of 264 m to a water depth of 110 m dissipation by large amplitude shear instabilities was observed the kinetic energy density was found to be a decreasing monotonic function of range with an energy dissipation rate coefficient of 0 063 km 1 the rate of energy dissipation over the 16 5 km soliton propagation path was 0 17 w m m simple numerical models of the waveform evolution are qualitatively compared to the observations the observations extracted scale parameters and dissipation rates should be useful for testing a variety of evolution equation representations of internal soliton propagation

late pliocene early pleistocene paleoceanographic evolution of the sea of japan abstract the stratigraphic distribution and abundance of molluscs and planktonic foraminifera within a sixth order 41 kyr depositional sequence of the early pleistocene omma formation in central japan provide several important information on the sea of japan since 2 5 ma the sea possibly experienced three substages in the paleoceanographic history since then during substage i 2 5 1 71 ma oxygen isotope stage 60 59 cold northern surface water prevailed due to the closure of the sea s southern entrance during substage ii 1 71 1 52 ma stage 51 the warm tsushima current flowed into the sea from the south during interglacial highstands during substage iii 1 52 0 ma isolation of the sea of japan was reinforced by narrowing and or shallowing of the northern entrance these changes were caused by some local tectonic movements that affected topography of the southern and northern straits inflow of the tsushima current resulted in migration of warm water organisms into the sea of japan during interglacial stages and acted as a barrier to the migration of terrestrial organisms between east asia and japanese islands

carbonate dissolution in recent sediments of the eastern equatorial indian ocean preservation patterns and carbonate loss above the lysocline abstract multiple dissolution indices from 45 sediment samples show that the foraminiferal lysocline is near 3800 m in the eastern equatorial indian ocean close to the saturation horizon with respect to calcite in the water column below the lysocline the increase in foraminiferal fragmentation decrease in absolute abundance and progressive modification of planktic foraminiferal assemblages with depth is accompanied by an increasing rate of loss of carbonate from the sediments above the lysocline some dissolution must occur in order to produce the dramatic reduction in foraminiferal numbers up to 60 and the pattern of increased fragmentation with depth however the amount of carbonate actually lost from supralysoclinal sediments reaches at most 20 30 of the total at the depth of the lysocline the principal driving force behind supralysoclinal dissolution is most likely the oxidation of organic matter incorporated into the sediments dissolution above the lysocline has a greater apparent impact on relative preservation in the coarse 150 m fraction than it does on total carbonate loss because of redistribution of carbonate to the finer size fractions as fragments though the effects of dissolution on foraminiferal preservation are clearly visible at all depths the lysocline itself does appear to mark the local onset of large scale loss of dissolved carbonate from the sediments such an interpretation is broadly consistent with models regarding the saturation state of the overlying waters as the principal driving force behind the preservation or dissolution of recent carbonate sediments on the sea floor

the role of symbiotic algae in the formation of the coral polyp skeleton 3 d morphological study based on x ray microcomputed tomography symbiotic algae of primary polyps play an important role in calcification of coral skeletons however the function of the symbiotic algae including the way they influence the physical features of their host skeleton under various conditions is not well understood we used x ray micro computed tomography to observe skeletal shape characteristics in symbiotic and aposymbiotic primary polyps of acropora digitifera that were cultured at various temperature and pco2 levels temperature 27 29 33 c pco2 400 800 1000 atm symbiotic polyps had a basal plate with a well developed folding margin supporting the branched skeleton whereas aposymbiotic ones did not the features of the folding margin suggest that it might be the initial growth stage of the epitheca in addition three dimensional 3 d morphological measurements made by x ray micro computed tomography show that the branched skeletons of symbiotic primary polyps were taller than those of aposymbiotic ones suggesting that zooxanthellae in coral primary polyps play a critical role in the height growth of skeletal branches furthermore results of the temperature and pco2 controlled experiments suggest that global warming might greatly affect the activity of zooxanthellae whereas ocean acidification might reduce calcification by damaging the coral host itself our findings provide new knowledge about the role of zooxanthellae in coral calcification this article is protected by copyright all rights reserved

effects of seawater carbonate ion concentration and temperature on shell u mg and sr in cultured planktonic foraminifera we investigate the sensitivity of u ca mg ca and sr ca to changes in seawater co3 and temperature in calcite produced by the two planktonic foraminifera species orbulina universa and globige rina bulloides in laboratory culture experiments our results demonstrate that at constant temperature u ca in o universa decreases by 25 7 per 100 mol co3 k g 1 as seawater co3 increases from 110 to 470 mol kg 1 results from g bulloides suggest a similar relationship but u ca is consistently offset by 40 at the same environmental co3 in o universa u ca is insensitive to temperature between 15 c and 25 c applying the o universa relationship to three u ca records from a related species globigerinoides sacculifer we estimate that caribbean and tropical atlantic co3 was 110 70 mol kg 1 and 80 40 mol kg 1 higher respectively during the last glacial period relative to the holocene this result is consistent with estimates of the glacial interglacial change in surface water co3 based on both modeling and on boron isotope ph estimates in settings where the addition of u by diagenetic processes is not a factor down core records of foraminiferal u ca have potential to provide information about changes in the ocean s carbonate concentration below ambient ph ph 8 2 mg ca decreased by 7 5 o universa t o 16 6 g bulloides per 0 1 unit increase in ph above ambient ph the change in mg ca was not significant for either species this result suggests that mg ca based paleotemperature estimates for the quaternary during which surface ocean ph has been at or above modern levels have not been biased by variations in surface water ph sr ca increased linearly by 1 6 0 4 per 0 1 unit increase in ph shell mg ca increased exponentially with temperature in o universa where mg ca 0 85 exp 0 096 t whereas the change in sr ca with temperature was within the reproducibility of replicate measurements copyright 2004 elsevier ltd

a mesoscale eddy pair southwest of taiwan and its influence on deep circulation 1 a pair of mesoscale eddies namely an anticyclonic eddy ae and a cyclonic eddy ce generated southwest of taiwan was investigated using long term moored observations augmented with satellite and reanalysis data ae ce increased the upper ocean current to 100 cm s 50 cm s and generated temperature anomaly t up to 7 5 c 3 0 c the vertical structure of ae presented a phase difference between t and velocity with the core of t located south of the zero velocity line this phase difference induced a 28 5 12 0 tw 1 tw 1012 w westward eddy heat transport southwest of taiwan ae also presented strong nonlinearity in the upper ocean and yielded an annual mean volume transport of 0 86 0 15 sv energy analysis showed that both baroclinic and barotropic instabilities were important for the generation and growth of the eddy pair and contribution from wind work was relative small in the deep sea ae ce intensified the deep currents and generated large positive negative t the deep and surface currents flowed in opposite directions during the eddy events which is consistent with the interpretation that the eddy pair is dominated by the first baroclinic mode the observed deep penetrating eddy pair could greatly influence the deep circulation of the northeastern south china sea

deep sea ostracode species diversity response to late quaternary climate change late quaternary ostracode assemblages from the north atlantic ocean were studied to establish the effect of climatic changes of the past 210 000 yr marine oxygen isotope stages 7 1 on deep sea benthic biodiversity and faunal composition two hundred and twenty five samples from thechain 82 24 core 4pc 41o43 0 n 32o51 0 w 3427 m water depth on the western mid atlantic ridge revealed high amplitude fluctuations in ostracode abundance and diversity coincident with orbital and suborbital scale climate oscillations measured by several paleoceanographic proxy records during the past 210 000 yr ostracode biodiversity as measured by species number s and the shannon weaver index h s oscillated from h s d 0 4 during glacial periods marine isotope stages 6 5d 5b 4 and 2 to h s d 1 1 during interglacial and interstadial periods stages 7 5e 5c 5a 3 and 1 a total of 23 diversity peaks could be recognized eleven of these signify major periods of high diversity h s 0 8 sd 10 21 occurring every 15 20 ka twelve were minor peaks which may represent millennial scale diversity oscillations the composition of ostracode assemblages varies with krithe dominated assemblages characterizing glacial intervals and argilloecia cytheropteroncharacterizing deglacials and trachyleberid genera poseidonamicus echinocythereis henryhowella oxycythereis abundant during interglacials diversity and faunal composition changes can be matched to independent deep sea paleoceanographic tracers such as benthic foraminiferal carbon isotopes krithe trace elements mg ca ratios and to north atlantic region climate records such as greenland ice cores when interpreted in light of ostracode species ecology these faunal and diversity patterns provide evidence that deep sea benthic ecosystems experience significant reorganization in response to climate changes over orbital to millennial timescales published by elsevier science b v

the relationship between shell size and mg ca sr ca δ18o and δ13c of species of planktonic foraminifera the relationship between shell size and mg ca sr ca 18o and 13c of planktonic foraminiferal calcite has been investigated using seventeen species in six different size fractions mg ca increases and sr ca decreases with increasing size except for two globorotaliid species which show the opposite trend the changes in mg ca broadly follow 18o calcification temperatures except that surface and near surface dwelling species show larger changes in mg ca than can be accounted for by differences in calcification temperature derived from 18o the increases in mg ca and decreases in sr ca vary linearly with the well established increase in 13c with size this is consistent with smaller individuals calcifying faster than larger individuals and larger individuals forming calcite that more closely reflects seawater temperature and composition it appears that variations in calcification rate affect mg and sr shell chemistry the observations may account for part of the temporal variability in foraminiferal sr ca within a single size fraction that has been attributed to changes in seawater sr ca

pleistocene deep sea ostracods from the oki ridge sea of japan iodp site u1426 and condition of the intermediate water the sea of japan also termed the east sea has a circulation system isolated from the pacific ocean and east china sea the east asian winter monsoon drives the circulation system and cools the tsushima warm current twc to form the japan sea intermediate proper water jsipw the intermediate water conveys oxygen to deep sea floors which is available for benthic animals during the pliocene 3 5 2 8 ma temperate intermediate water tiw was formed under the weak winter monsoon and extinct ostracod tiw taxa were found little is known about early pleistocene intermediate water and the extinction mode of benthic ostracods we studied radiolarians and ostracods from deep sea sediments between 2 0 and 1 3 ma marine oxygen isotope stage mis 77 to mis 41 at integrated ocean drilling program site u1426 sea of japan the ostracod faunas contained tiw and jsipw taxa the radiolarian subtropical water taxa and the jsipw ostracods indicate a small influx of the twc and the jsipw the tiw occasionally expanded to the middle bathyal zone by analogy with the relationship between the modern jsipw and winter monsoon weak winter monsoon possibly caused gentle temperature gradients in the water column and the expansion of the tiw the jsipw taxa expanded their ranges into the deep sea during interglacial periods

okhotsk sea ostracods in surface sediments depth distribution of cryophilic species relative to oceanic environment abstract the depth distribution of benthic ostracods in surface sediments of the southern okhotsk sea in the marginal northwestern pacific reflects environmental factors such as water depth water mass properties and sea ice transport ostracods are much more abundant on the continental shelf than on the continental slope with only a few specimens present on the lower slope many species in this study area are identical to cryophilic species in the northern japan sea which lies adjacent to the southern okhotsk sea comparison of the depth distribution patterns of shallow water e g johnnealella nopporensis and munseyella hatatatensis and deep water e g argilloecia toyamaensis species in the northern japan sea reveals two relationships 1 the depth distribution range of j nopporensis m hatatatensis and other species in the okhotsk sea upper shelf to upper continental slope 50 500 m is greater than in the japan sea upper to middle shelf 40 120 m 2 the abundances of a toyamaensis and other species on the continental slope of the okhotsk sea are lower than on the japan sea slope the presence of a few shallow water species such as m hatatatensis on the upper continental slope of the okhotsk sea is probably the result of ice rafting the low abundance of a toyamaensis and other species in the okhotsk sea reflects both lower dissolved oxygen values compared to the northern japan sea and the shallow depth of soya strait that connects the two seas

early pleistocene glacio eustatic sea level fluctuations as deduced from periodic changes in cold and warm water molluscan associations in the shimokita peninsula northeast japan abstract sea level oscillations of apparently glacio eustatic origin are recognized in the lower pleistocene hamada formation based on changes of molluscan associations there are two cold water molluscan associations the turritella saishuensis macoma clinocardmium and the acila macoma associations and one warm water limopsis crenata limatula nuculana association their distribution in time and space indicates that the study area was dominated by cold water and was invaded periodically by warm water at least three times in the early pleistocene between 1 10 ma and 0 89 ma judging from their species composition the paleodepth was greater during the times of warm water intrusion than during the times dominated by cold water the phenomena are reasonably explained by a combination of climatic and sea level changes

characterization of contaminant phases in foraminifera carbonates by electron microprobe mapping the advent of new microanalytical techniques such as electron microprobe mapping emp and laser ablation microsamplers coupled to mass spectrometers la icp ms provides a new array of possibilities to explore in great detail the trace elements distribution in foraminiferal carbonates here we apply these techniques to characterize diagenetic phases present in foraminiferal shells from ocean drilling program site 1240 in the panama basin a region characterized by the presence of manganese rich minerals in the sediments the combined application of these techniques allows us to characterize the elemental and spatial distribution on the surface and across the foraminiferal shells results illustrate the presence of at least two different mn rich contaminant phases in the foraminiferal carbonates mn rich carbonates and ferromanganese oxides elemental maps also highlight the relevance of the foraminifera shell texture and porosity in the distribution and formation of these contaminant phases in the case of neogloboquadrina dutertrei mn phases form a continuous thin layer in the inner part of the chambers whereas for globigerinoides ruber mn phases have a rather patchy distribution and are usually found within the pores significant high magnesium concentrations are always associated with these mn rich phases these new findings support the need of removing these mn rich contaminant phases in order to measure accurately the mg ca ratios in the foraminifera shell and therefore obtain reliable mg ca paleotemperature reconstructions

impacts of a mesoscale eddy pair on internal solitary waves in the northern south china sea revealed by mooring array observations abstractboth internal solitary waves isws and mesoscale eddies are ubiquitous in the northern south china sea scs in this study the authors examine the impacts of mesoscale eddies on the isws transiting the northern scs deep basin that evolve from the steepening internal tide generated in the luzon strait using in situ data collected from a specifically designed mooring array from november 2013 to january 2014 an energetic mesoscale eddy pair consisting of one anticyclonic eddy ae and one cyclonic eddy ce propagated across the mooring array observations revealed that the amplitude propagation direction and speed of the transbasin isws were significantly modulated by the eddy pair when the moorings were covered by the southern portion of the ae the isw amplitudes decreased by as much as 67 because of the thermocline deepening along the wave direction and the energy divergence along the wave front when the moorings were covered by the northern portions of both eddies the amplitude of is

cyclic sea level changes based on fossil ostracode faunas from the upper pliocene sasaoka formation akita prefecture northeast japan abstract the paleoenvironments in the upper pliocene sasaoka formation 2 20 2 05 ma gojome area akita prefecture northeast japan are reconstructed on the basis of the ostracode assemblages and sedimentary facies the upper part of this formation is divided into five units representing sedimentary facies each unit shows coarsening upward sequences q mode principal component analysis of ostracodes suggests the following 1 the upper pliocene sasaoka formation was deposited entirely under cold water influences and 2 paleoenvironments of this formation are interpreted as combinations of a coastal area in sublittoral zone open water environment in upper bathyal zone a bay in upper bathyal zone and a bay in sublittoral zone each of four sedimentary units records one cycle of relative sea level change based on ostracode assemblages whereas one sedimentary unit ii is barren the sea level changes reflected in the upper two units iv and v might have been shorter in duration than those of the lower two units i and iii relatively large amplitude oscillation is recognized in the middle part by presence of lag deposits absence of the upper part of a cycle in unit below the lag deposit and no correlation between ostracode assemblages and paleodepth just above the lag deposits this large shift might have been caused by the global glacial event at 2 08 ma the paleodepth between upper bathyal and sublittoral zone shifts to shoreface at the remarkable boundary the upper half is characterized by a shallowing upward sequence based on occurrences of sinocytheridea latiovata

remote sensing evidence for baroclinic tide origin of internal solitary waves in the northeastern south china sea 1 evidence for baroclinic tide origin of internal solitary waves isws in the northeastern south china sea is presented based on 116 internal wave packets observed in satellite images from 1995 to 2001 these wave packets can be divided into two types a single wave isw packet containing only one isw with without an oscillating tail and a multiple wave isw packet composed of a group of rank ordered isws all of the 22 single wave isw packets occur in the deep water zone it is suggested that the isws instead of being generated by the lee wave mechanism are developed by nonlinear steepening of the baroclinic tides which are produced by the strong tidal currents flowing over a ridge in luzon strait this suggestion is verified by an ers 2 sar image which records such an evolution process from a baroclinic tide to a single isw in its spatial domain

effect of preservation state of planktonic foraminifera tests on the decrease in mg ca due to reductive cleaning and on sample loss during cleaning four species of planktic foraminifera from core tops spanning a depth transect on the ontong java plateau were prepared for mg ca analysis both with cd cleaning and without mg cleaning a reductive cleaning step reductive cleaning caused etching of foraminiferal calcite focused on mg rich inner calcite even on tests which had already been partially dissolved at the seafloor despite corrosion there was no difference in mg ca of pulleniatina obliquiloculata between cleaning methods reductive cleaning decreased mg ca by an average all depths of 4 for globigerinoides ruber white and 10 for neogloboquadrina dutertrei mg ca of globigerinoides sacculifer above the calcite saturation horizon only was 5 lower after reductive cleaning the decrease in mg ca due to reductive cleaning appeared insensitive to preservation state for g ruber n dutertrei and p obliquiloculata mg ca of cd cleaned g sacculifer appeared less sensitive to dissolution than that of mg cleaned mg cleaning is adequate but sem and contaminants al ca fe ca and mn ca show that cd cleaning is more effective for porous species a second aspect of the study addressed sample loss during cleaning lower yield after cd cleaning for g ruber g sacculifer and n dutertrei confirmed this to be the more aggressive method strongest correlations between yield and co32 in core top samples were for cd cleaned g ruber r 0 88 p 0 020 and cd cleaned p obliquiloculata r 0 68 p 0 030 in a down core record wind28k correlation r between yield values 30 and dissolution index xdx was 0 61 p 0 002 where cleaning yield 30 most mg cleaned mg ca values were biased by dissolution

mg ca variation in planktonic foraminifera tests implications for reconstructing palaeo seawater temperature and habitat migration the nature of compositional variability within the tiny calcitic shells tests that are precipitated by planktonic foraminifera has been investigated using laser ablation inductively coupled plasma mass spectrometry la icp ms systematic large and correlated variation of mg ca mn ca ba ca and zn ca but relatively uniform sr ca are observed through the test walls of analysed species globigerinoides sacculifer globigerinoides ruber neogloboquadrina pachyderma and neogloboquadrina dutertrei distinct chamber and chamber wall layer compositions can be resolved within individual tests and mg ca compositional differences observed in sequentially precipitated test components of the different species analysed are consistent with seawater temperature changes occurring with habitat migration during their adult life cycle stages estimated test calcification temperatures are in keeping with available seawater temperature constraints indicating the potential for accurate seawater temperature reconstruction using la icp ms mg rich 1 6 mol mg surface veneers that are also enriched in mn ba and zn have been found on all species and all fossil tests as well as on live sampled tests of g ruber with the latter suggesting a possible biogenic origin these mg rich surfaces bias bulk test compositions toward higher mg ca values by between 5 and 35

variations in mg ca and sr ca ratios of planktonic foraminifera caused by postdepositional dissolution evidence of shallow mg dependent dissolution a comparative study has been made of two species of planktonic foraminifera g tumida and g sacculifer in a depth transect on the ontong java plateau western equatorial pacific g tumida tests from core top sediments showed decreasing mg ca 2 65 1 25 mmol mol and sr ca 1 50 1 16 mmol mol ratios with increasing water depth 1600 4400 m while no such variation was found in g sacculifer tests in excess of 355 m average mg ca 3 6 mmol mol sr ca 1 4 mmol mol artificial dissolution of g tumida tests led to a decrease in both mg ca and sr ca but in g sacculifer there was no significant change in the ratios analyses by electron microprobe revealed that mg ca of the inner chamber calcite in g tumida tests was much higher than that of the calcite crust keel whereas sr ca was only slightly elevated there were no consistent spatial differences in either mg ca or sr ca for g sacculifer tests dissolution in the oceans gives rise to the removal of the chamber calcite in g tumida about 30 of the total calcite leaving the keel calcite although g tumida is thought of as a dissolution resistant form the majority of mg ca and sr ca depletion and chamber loss occurs above the lysocline it is also possible that much of the mg enriched gametogenic calcite has been lost by dissolution from g sacculifer above 1600 m mg content has a significant effect on the dissolution susceptibility of planktonic foraminifera calculations show that the saturation horizon for mg rich parts of tests may be elevated by several hundred meters compared with normal calcite

inside story an x ray computed tomography method for assessing dissolution in the tests of planktonic foraminifera x ray computed tomography ct provides an insight into the progression of dissolution in the tests of planktonic foraminifera four species of foraminifera g ruber white g sacculifer n dutertrei and p obliquiloculata from pacific atlantic and indian ocean core top samples were examined by ct and sem inner chamber walls began to dissolve at co32 values of 12 14 mol kg close to the calcite saturation horizon dissolution and precipitation of calcite may occur simultaneously inner calcite of g sacculifer n dutertrei and p obliquiloculata from such sites appeared altered or replaced whereas outer crust calcite was dense with no pores unlike the other species there was no distinction between inner and outer calcite in ct scans of g ruber empty calcite crusts of n dutertrei and p obliquiloculata were most resistant to dissolution and were present in samples where co32 20 mol kg five stages of preservation were identified in ct scans and an empirical dissolution index xdx was established xdx appears to be insensitive to initial test mass mass loss in response to dissolution was similar between species and sites at 0 4 g mol kg we provide calibrations to estimate co32 and initial test mass from xdx

evolution of a shoaling internal solitary wavetrain 1 field observations of an internal solitary wavetrain impacting a shoaling bottom are presented measurements of the spatio temporal characteristics of the shoaling waves are given as well as estimations of the mixing they may have caused upon impact the observations are discussed in the context of numerical simulations laboratory experiments and hypotheses recently raised on the origin and evolution of internal solitary waves in coastal environments

quaternary time scale for the ontong java plateau milankovitch template for ocean drilling program site 806 a 2 m y oxygen isotope record of globigerinoides sacculifer from the ontong java plateau based on cores from ocean drilling program leg 130 is dated by matching variations to an orbital template the procedure allows us to present the most complete quaternary record available for the western equatorial pacific the template generating algorithm describes a balance between growth and melting of ice following basic milankovitch theory ice growth is taken as constant while melting is taken to depend on summer insolation current ice mass and average past ice mass template settings must be changed once between 1 and 1 2 ma to reflect a major shift in climate template fits are strikingly good over much of the record and can be used to detect and fill gaps from core breaks and other disturbances one result of template dating is an exact age for the brunhes matuyama magnetic reversal boundary at 790 5 ka as well as several other precise dates 900 ka for the middle pleistocene climate shift 1070 1240 and 1450 ka for isotope stages 31 37 and 47 respectively sedi mentation rates fluctuate between 18 and 28 m m y a ca 400 ka cycle being the most prominent major anomalies arise within the transitional regime 1 2 to 1 ma the origin of the cycles is unknown we propose productivity variations in the western equatorial pacific

polarity variations of internal solitary waves over the continental shelf of the northern south china sea impacts of seasonal stratification mesoscale eddies and internal tides abstractspatiotemporal variations in internal solitary wave isw polarity over the continental shelf of the northern south china sea scs were examined based on mooring array observations from october 2013 to june 2014 depression isws were observed at the easternmost mooring where the water depth is 323 m then they evolved into elevation isws at the westernmost mooring with a depth of 149 m at the central mooring with a depth of 250 m the isws generally appeared as depression waves in autumn and spring but were elevation waves in winter seasonal variations in stratification caused this seasonality in polarity on the intraseasonal time scales anticyclonic eddies can modulate isw polarity at the central mooring by deepening the thermocline depth for periods of approximately 8 days during some days in autumn and spring depression isws and isws in the process of changing polarity from depression to elevation appeared at time intervals of 10 12 h because of the thermocline deepening caused by in

present water mass calcium carbonate corrosiveness in the eastern south atlantic inferred from ultrastructural breakdown of globigerina bulloides in surface sediments abstract the atlantic is regarded as a huge carbonate depocenter due to an on average deep calcite lysocline however calculations and models that attribute the calcite lysocline to the critical undersaturation depth hydrographic or chemical lysocline and not to the depth at which significant calcium carbonate dissolution is observed sedimentary calcite lysocline strongly overestimate the preservation potential of calcareous deep sea sediments significant calcium carbonate dissolution is expected to begin firstly below 5000 m in the deep guinea and angola basin and below 4400 m in the cape basin our study that is based on different calcium carbonate dissolution stages of the planktic foraminifera globigerina bulloides clearly shows that it starts between 400 and 1600 m shallower depending on the different hydrographic settings of the south atlantic ocean in particular coastal areas are severely affected by increased supply of organic matter and the resultant production of metabolic co2 which seems to create microenvironments favorable for dissolution of calcite well above the hydrographic lysocline

temporal changes in north atlantic circulation constrained by planktonic foraminiferal shell weights records of planktonic foraminiferal shell weights for globigerina bulloides covering termination i from four proximal sites at waters depths from 1150 to 4045 m in the northeast atlantic demonstrate the influence of dissolution superimposed upon initial shell weight variability records of shell weight unaffected by dissolution may be used as a reference for interpreting deeper records in terms of preservation history combining records of planktonic shell weight and benthic 13c from shallow and deep sites suggests that maximum oceanic stratification and incursion of southern sourced deep waters in the north atlantic occurred at about 18 20 ka defining the glacial mode of atlantic circulation reduced stratification and enhanced preservation in deeper waters reflect conditions during heinrich event 1 a state similar to the modern mode of atlantic circulation was attained by about 10 ka

modulation and daily banding of mg ca in orbulina universa tests by symbiont photosynthesis and respiration a complication for seawater thermometry the mg ca composition of calcium carbonate tests shells secreted by planktonic foraminifera is increasingly being employed to estimate past seawater temperatures and reconstruct paleocean and climate records spanning hundreds of thousands of years we show using two high resolution microanalysis techniques that the final chamber of the planktonic foraminifera orbulina universa typically comprises between three and six paired low and high mg growth bands the number and spacing of these bands is consistent with a diurnal origin modulated by changing ph within the foraminiferal microenvironment due to the day night photosynthesis respiration cycle of algal symbionts the amplitude of mg ca variation within individual tests and across many daily growth bands cannot be accounted for by seawater temperature in the shallow euphotic zone habitat of o universa our results indicate the mg ca composition of calcite precipitated by o universa in nature is strongly influenced by diurnal changes in the biological activity of algal symbionts and the host foraminifer this brings into question the fundamental premise often made in applying mg ca palaeoseawater thermometry that the mg ca composition of foraminiferal calcite is determined by seawater temperature and whether the mg ca composition of other planktonic species that are more widely used for palaeoseawater thermometry are subject to similar influences 2004 elsevier b v all rights reserved

the potential of ion microprobe analysis in detecting geochemical variations across individual foraminifera tests 1 trace element chemistry variations within individual foraminifera tests may provide valuable information on past ocean conditions however the combination of thin test walls and the presence of surface contaminants not held within the carbonate structure provide a stringent test to microanalytical methods we analysed two tests of the benthic foraminifera ammonia batavus by ion microprobe and compared two sets of analytical conditions using apertures to restrict the size of the analysed area to ca 10 m diameter reduced the effects of sample contamination sr concentrations were unaffected by any contamination encountered and mg could be determined provided checks were made for silicate contamination using al si and k intensities measured sr concentrations 1 012 1 379 mmol mol 1 were in reasonable agreement with previously reported values mg concentrations 0 691 1 412 mmol mol 1 were significantly lower than values reported previously for calcitic benthic species significant variations in sr concentrations occurred within individual test chambers and may reflect the juxtapositioning of calcite of different ages as the test is deposited significant variations in mg and sr concentrations also occurred between test chambers

a nonlinear model of internal tide transformation on the australian north west shelf a numerical solution to the generalized korteweg de vries k dv equation including horizontal variability and dissipation is used to model the evolution of an initially sinusoidal long internal wave representing an internal tide the model shows the development of the waveform to the formation of shocks and solitons as it propagates shoreward over the continental slope and shelf the model is run using observed hydrographic conditions from the australian north west shelf and results are compared to current meter and thermistor observations from the shelf break region it is found from observations that the coefficient of nonlinearity in the k dv equation changes sign from negative in deep water to positive in shallow water and this plays a major role in determining the form of the internal tide transformation on the shelf there is strong temporal variability in the nonlinear coefficient due to both background shear flow and the large amplitude of the internal tide which distorts the density profile over a wave period both the model and observations show the formation of an initial shock on the leading face of the internal tide in shallow water the change in sign of the coefficient of nonlinearity causes the shock to evolve into a tail of short period sinusoidal waves after further propagation a second shock forms on the back face of the wave followed by a packet of solitons the inclusion of bottom friction in the model is investigated along with the dependance on initial wave amplitude and variability in the coefficients of nonlinearity and dispersion friction is found to be important in limiting the amplitudes of the evolving waves

palaeoceanographic records related to glacio eustatic fluctuations in the pleistocene japan sea coast based on ostracods from the omma formation abstract six palaeo water depth oscillations in response to glacio eustacy during ca 1 5 1 25 ma were recognized based on the changes of ostracod assemblages from the coastal sediments of the omma formation in the noto peninsula on the coast of the japan sea in central japan this is the first report of glacio eustatic sea level changes from the shallow coastal sediments between ca 1 5 and 1 3 ma and the process of stepped intensification of the magnitude of the sea level change is illustrated clearly for the first time shallow cold water and relatively deeper warm water fossil assemblages appear alternatively in the omma formation this mode of occurrence indicates that sea level rise occurred repeatedly in parallel with a marine climatic warming these palaeo water depth changes occurred with a periodicity of a few tens of thousands of years and the six sea level rises can be assigned to oxygen isotope stages 49 39 when compared with the oxygen isotope fluctuation curve from the north atlantic deep sea sediments records the first three sea level changes probably correlate with stages 49 47 and 45 and had a magnitude of fluctuation of 10 20 m this was followed by stages 43 41 and 39 with a magnitude of fluctuations of 50 60 m for stage 43 and 70 80 m for stage 39 the process of intensification of the amplitude is reflected in the increase of the thickness of warm water influx into the japan sea at high sea level stand during this period which developed from 20 30 m into ca 100 m

the formation and fate of internal waves in the south china sea internal oceanic waves are subsurface gravity waves that can be enormous and travel thousands of kilometres before breaking but they are difficult to study here observations of such waves in the south china sea reveal their formation mechanism extreme turbulence relationship to the kuroshio current and energy budget internal waves are the underwater version of more familiar surface waves they can be enormous and travel thousands of kilometres before breaking the south china sea is known to be home to the largest internal waves in the world s oceans but their size generation mechanisms and role in the regional energy budget are unknown matthew alford and colleagues now present the results from the iwise observational campaign and reveal that internal waves more than 200 metres high break in the south china sea and create turbulence that is orders of magnitude larger than in the open ocean and that wave formation is influenced by the kuroshio current these results now allow for a complete energy budget of the south china sea and for a more accurate incorporation of internal waves into climate models internal gravity waves the subsurface analogue of the familiar surface gravity waves that break on beaches are ubiquitous in the ocean because of their strong vertical and horizontal currents and the turbulent mixing caused by their breaking they affect a panoply of ocean processes such as the supply of nutrients for photosynthesis1 sediment and pollutant transport2 and acoustic transmission3 they also pose hazards for man made structures in the ocean4 generated primarily by the wind and the tides internal waves can travel thousands of kilometres from their sources before breaking5 making it challenging to observe them and to include them in numerical climate models which are sensitive to their effects6 7 for over a decade studies8 9 10 11 have targeted the south china sea where the oceans most powerful known internal waves are generated in the luzon strait and steepen dramatically as they propagate west confusion has persisted regarding their mechanism of generation variability and energy budget however owing to the lack of in situ data from the luzon strait where extreme flow conditions make measurements difficult here we use new observations and numerical models to 1 show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena 2 reveal the existence of 200 metre high breaking internal waves in the region of generation that give rise to turbulence levels 10 000 times that in the open ocean 3 determine that the kuroshio western boundary current noticeably refracts the internal wave field emanating from the luzon strait and 4 demonstrate a factor of two agreement between modelled and observed energy fluxes which allows us to produce an observationally supported energy budget of the region together these findings give a cradle to grave picture of internal waves on a basin scale which will support further improvements of their representation in numerical climate predictions

anticyclonic eddy sheddings from kuroshio loop and the accompanying cyclonic eddy in the northeastern south china sea abstractsheddings of kuroshio loop current klc eddies in the northeastern south china sea scs are investigated using mooring arrays multiple satellite data and data assimilative hycom products based on altimeter sea surface heights between 1992 and 2014 a total of 19 prominent klc eddy shedding klces events were identified among which four events were confirmed by the concurrent moored and satellite observations compared to the leaping behavior of kuroshio klces is a relatively short duration phenomenon that primarily occurs in boreal autumn and winter the klc and its shedding anticyclonic eddy ae trap a large amount of pacific water with high temperature salinity and low chlorophyll concentration in the upper layer the corresponding annual mean transport caused by klces reaches 0 24 0 38 sv 1 sv 106 m3 s 1 accounting for 6 8 10 8 of the upper layer luzon strait transport altimeter based statistics show that among 90 of the historical klces events a cyclonic eddy ce is immedi

planktonic foraminifera differential dissolution and the quaternary stable isotope record in the west equatorial pacific differential dissolution affects the isotopic composition of different species of planktonic foraminifera in different ways in the two species studied here in cores from ontong java plateau the less resistant species globigerinoides sacculifer is more readily affected at a shallower depth than the more resistant species pulleniatina obliquiloculata 2 9 versus 3 4 km but shows a smaller and less predictable response to partial dissolution 0 2 to 0 3 per mil versus 0 6 to 0 7 per mil comparison of isotopic values from the last glacial period with those from the late holocene indicates that the apparent dissolution effect is considerably reduced during the last glacial presumably due to reduced dissolution intensity during glacial time a change in the level of the lysocline of about 400 m is suggested in the published isotope records from pacific cores v28 238 and v28 239 the dissolution generated difference in 18o noted previously by shackleton and opdyke 1976 is seen to describe a mid brunhes dissolution maximum between 300 and 500 thousand years ago this mid brunhes dissolution excursion is well known from the pacific and the indian ocean

satellite observation of internal solitary waves converting polarity 1 on a spot 3 visible image over the south china sea continental shelf two contrasting signatures of internal solitary waves isws are observed darker stripes leading brighter stripes in the lower part and brighter stripes leading darker stripes in the upper part the authors suggest that the contrasting patterns are caused by isws of different polarities a packet of isws is observed in the process of converting polarity due to bottom shoaling both in the propagation direction and in the transect direction the evolution process can be obtained by transferring information from the spatial domain to the temporal domain the conversion process starts with the original depression isws passing the 160 m isobath the evolution process can be divided into two phases the first is the broadening of the original depression waves and the second is the appearance of the new born elevation waves these two phases are verified using numerical simulation

biogeography and the pleistocene extinction of neogastropods in the japan sea during the middle to late pleistocene glacial lowstands when the japan sea was almost isolated geographically low salinity surface water and anoxic deep water were formed pliocene to early pleistocene buccinid gastropods which mainly lived deeper than the lower sublittoral zone underwent extinction owing to anoxic deep water on the other hand upper sublittoral muricid and buccinid species suffered from extinction due to decrease of surface salinity however fossil records indicate that species in the pacific ocean east of japan having shallow minimum depths reinvaded the japan sea through shallow northern straits at least in the latest pleistocene the fossil and recent records of two buccinum species restricted to the japan sea side indicate normal salinity and oxic water at ca 100 400 m during glacial lowstands 2003 elsevier b v all rights reserved

biotic response to late quaternary rapid climate switches in santa barbara basin ecological and evolutionary implications benthic foraminiferal assemblages from santa barbara basin exhibit major faunal and ecological switches associated with late quaternary millennial to decadal scale global climate oscillations repeated turnovers of entire faunas occurred rapidly 40 400 yr without extinction or speciation in conjunction with dansgaard oeschger shifts in thermohaline circulation ventilation and climate confirming evolutionary model predictions of roy et al consistent faunal successions of dysoxic taxa during successive interstadials reflect the extreme sensitivity and adaptation of the benthic ecosystem to the rapid environmental changes that marked the late quaternary and possibly other transitional intervals in the history of the earth s ocean atmosphere cryosphere system these data support the hypothesis that broad segments of the biosphere are well adapted to rapid climate change

micromapping of mg ca values in cultured specimens of the high magnesium benthic foraminifera 1 this study measured mg ca values in cross sections of the benthic foraminifer planoglabratella opercularis d orbigny using an electron probe microanalyzer epma spot size 2 m 1000 analyses we cultured clonal juveniles of this species under controlled temperatures this species precipitates high magnesium calcite as its test material mean mg ca values increased linearly with the culture temperature therefore mg ca values in walls of subsequently formed chambers reflected changes in temperature during the experiment foraminiferal specimens yielded variable mg ca values within their test walls which resulted from the pattern of chamber formation and from minor variations of mg ca within one chamber wall

calibration of mg ca thermometry in planktonic foraminifera from a sediment trap time series 1 paired mg ca and 18o measurements on planktonic foraminiferal species g ruber white g ruber pink g sacculifer g conglobatus g aequilateralis o universa n dutertrei p obliquiloculata g inflata g truncatulinoides g hirsuta and g crassaformis from a 6 year sediment trap time series in the sargasso sea were used to define the sensitivity of foraminiferal mg ca to calcification temperature habitat depths and calcification temperatures were estimated from comparison of 18o of foraminifera with equilibrium calcite based on historical temperature and salinity data when considered together mg ca mmol mol of all species except two show a significant r 0 93 relationship with temperature t c of the form mg ca 0 38 0 02 exp 0 090 0 003 t equivalent to a 9 0 0 3 change in mg ca for a 1 c change in temperature small differences exist in calibrations between species and between different size fractions of the same species o universa and g aequilateralis have higher mg ca than other species and in general data can be best described with the same temperature sensitivity for all species and pre exponential constants in the sequence o universa g aequilateralis g bulloides g ruber g sacculifer other species this approach gives an accuracy of 1 2 c in the estimation of calcification temperature the 9 sensitivity to temperature is similar to published studies from culture and core top calibrations but differences exist from some literature values of pre exponential constants different cleaning methodologies and artefacts of core top dissolution are probably implicated and perhaps environmental factors yet understood planktonic foraminiferal mg ca temperature estimates can be used for reconstructing surface temperatures and mixed and thermocline temperatures using g ruber pink g ruber white g sacculifer n dutertrei p obliquiloculata etc the existence of a single mg thermometry equation is valuable for extinct species although use of species specific equations will where statistically significant provide more accurate evaluation of mg ca paleotemperature

late pliocene climate change 3 4 2 3 ma paleoceanographic record from the yabuta formation sea of japan abstract late pliocene paleoceanographic changes in the sea of japan between 3 4 and2 3 ma were investigated through study of molluscs diatoms and ostracodes from the yabuta formation in toyama prefecture the period 3 4 2 7 ma was characterized by relatively high sea level and cool water benthic faunas a progressive paleoceanographic shift towards colder oceanic conditions and lower sea level occurred beginning near 2 7 ma intenifying about 2 5 ma when important changes in ostracode and molluscan faunas occurred between 2 7 and 2 3 ma eight glacial events can be inferred based on drops in sea level of 50 60 m and increasing proportions of cold shallow water ostracode species whose modern ecology and zoogeography indicate colder winter water temperatures 3 4 c the glacial events between 2 5 and 2 3 ma were the most intense preliminary interpretation of the faunal and oceanographic events of the yabuta formation suggests that they correspond to northern hemispheric cooling also known from north atlantic deep sea oxygen isotope ird and planktic foraminiferal records north pacific diatom and radiolarian record and the chinese loess sequences the eight glacial events may record a 41 000 yr obliquity cycle which characterized other late pliocene climate proxy records inferred sea level drops near 2 5 2 3 ma of about 50 60 m provide direct evidence from an ocean margin setting that supports deep sea oxygen isotopic evidence indicating major changes in global ice volume changes

excess dissolved ca in the deep ocean a hydrothermal hypothesis abstract variations in seawater alkalinity and dissolved calcium provide information essential to establishing the integrated deep ocean calcium carbonate dissolution flux high precision ca measurements reported here confirm earlier suggestions that the deep ocean contains higher levels of dissolved ca than expected from calcium carbonate dissolution only i propose that the mid depth ca excess is a manifestation of the circulation of seawater through hydrothermal systems at mid ocean ridges qualitative agreement with 3 he distributions and evidence for deep water mg depletions support this hypothesis the magnitude of the mid depth ca excess implies a total hydrothermal flux larger than expected from the corresponding excess in 3 he and points to the relative importance of low temperature diffuse fluxes versus high temperature discrete fluxes for elements such as ca the implied total hydrothermal flux for ca is consistent with its oceanic mass balance requirements and resolves several long standing problems associated with our understanding of the chemical evolution of the ocean and in particular its low alkaline content

simulation of the transformation of internal solitary waves on oceanic shelves abstract internal solitary waves transform as they propagate shoreward over the continental shelf into the coastal zone from a combination of the horizontal variability of the oceanic hydrology density and current stratification and the variable depth if this background environment varies sufficiently slowly in comparison with an individual solitary wave then that wave possesses a soliton like form with varying amplitude and phase this stage is studied in detail in the framework of the variable coefficient extended korteweg de vries equation where the variation of the solitary wave parameters can be described analytically through an asymptotic description as a slowly varying solitary wave direct numerical simulation of the variable coefficient extended korteweg de vries equation is performed for several oceanic shelves north west shelf of australia malin shelf edge and arctic shelf to demonstrate the applicability of the asymptotic theory it is shown that the solitary wave may maintain its sol

interlaboratory comparison study of mg ca and sr ca measurements in planktonic foraminifera for paleoceanographic research thirteen laboratories from the usa and europe participated in an intercomparison study of mg ca and sr ca measurements in foraminifera the study included five planktonic species from surface sediments from different geographical regions and water depths each of the laboratories followed their own cleaning and analytical procedures and had no specific information about the samples analysis of solutions of known mg ca and sr ca ratios showed that the intralaboratory instrumental precision is better than 0 5 for both mg ca and sr ca measurements regardless whether icp oes or icp ms is used the interlaboratory precision on the analysis of standard solutions was about 1 5 and 0 9 for mg ca and sr ca measurements respectively these are equivalent to mg ca based temperature repeatability and reproducibility on the analysis of solutions of 0 2 c and 0 5 c respectively the analysis of foraminifera suggests an interlaboratory variance of about 8 rsd for mg ca measurements which translates to reproducibility of about 2 3 c the relatively large range in the reproducibility of foraminiferal analysis is primarily due to relatively poor intralaboratory repeatability about 1 2 c and a bias about 1 c due to the application of different cleaning methods by different laboratories improving the consistency of cleaning methods among laboratories will therefore likely lead to better reproducibility even more importantly the results of this study highlight the need for standards calibration among laboratories as a first step toward improving interlaboratory compatibility

paleoceanographic evolution of the japan sea abstract multidisciplinary studies on nearly continuous hemipelagic sequences recovered from the deeper parts of the japan sea during odp leg 127 128 in 1989 yielded new information on the paleoceanographic conditions of the sea since its establishment as a deep marginal basin of significant size approximately at 20 ma by synthesizing these new information on surface and bottom water conditions ccd biogenic silica accumulation and paleogeog raphy it is possible to reconstruct changes in paleo ocean circulation within the sea it is also possible to specify the ultimate cause of such changes by comparing their timing and nature with those of global paleoceanographic as well as local tectonic events the result of our synthesis suggests that the japan sea has been responding to the high frequency changes of global surface conditions in very sensitive manner throughout its history however the mode of its response changed from time to time the changes in response mode have been strongly influenced by such factors as sill depth position of channels and the degree of closure of the sea which were controlled either by local tectonism or global eustatic sea level changes

the effects of glacio eustatic sea level change on pleistocene cold water ostracod assemblages from the japan sea abstract the pleistocene palaeo habitats and the extinction history of cold water ostracods in the japan sea are recorded in its coastal strata the presence of now extinct species in the omma formation of central japan 1 5 ma indicates that such species predominated in a shallow open sea environment the tolerance ranges of these species as to water temperature and salinity are inferred to have been narrower than those of most extant cold water species in the same families that live in shallow open water as well as in brackish inner bays the horizons in the omma formation with peak relative abundances of now extinct species differ from the horizons with peak abundances of living japan sea species we therefore suggest that the now extinct species were adapted to optimum temperature and salinity conditions that differ from those in the modern japan sea the observation that few now extinct species survived after 0 4 ma may be explained by the hypothesis that physicochemical properties of the water masses changed we argue that during the glacial periods with increased amplitude 0 9 0 4 ma the salinity decreased as the result of glacio eustatic changes and the closure of shallow straits owing to low sea levels causing the extinctions

prototypical solitons in the south china sea 1 surface signatures associated with non linear internal waves are often seen in satellite images of the western south china sea scs slope and shelf observation in the deep sea to the east are rare here we report on the evolution of an energetic packet as it propagated through the deep central basin of the scs toward the western slope and shelf the waves have amplitudes estimated at 170 m half widths of 3 km and phase speeds of 2 9 0 1 m s faster than the mode 1 linear phase speed of 2 6 m s the shape and observed phase speed were consistent with the korteweg devries kdv model over the 65 km path that they were tracked the intrinsic velocity shear of the waves is small compared to pre existing shears and the waves exhibit weak turbulence the kdv fit and a satellite derived estimate of horizontal wave extent imply a westward energy flux of 4 5 gw for each crest

barium in planktonic foraminifera abstract reconstructions of ba distributions in ancient oceanic surface waters could provide new insight into paleoceanographic change calcite shells of planktonic foraminifera potentially provide a means of reconstructing such paleo ba distributions if lattice bound ba can be determined on shells recovered from deep sea cores planktonic foraminifera shells from a series of cores were purified of non lattice bound ba associated with organic or sedimentary phases by a combination of physical agitation oxidative reductive steps acid leaches and a novel alkaline dtpa step to dissolve barite a sequential dissolution of a large sample of cleaned shells of the planktonic foraminifer globigerinoides conglobatus indicates homogeneous distribution of ba in the shell material comparison of shells from sediments sediment traps and plankton tows indicates no significant differences in the ba content of the purified shells cleaned samples of the planktonic foraminifera globigerinoides sacculifera g ruber g conglobatus orbulina spp and globoquadrina dutertrei from the equatorial pacific north atlantic and mediterranean sea have ba ca ratios between 0 6 and 1 0 mol mol 0 8 to 1 4 ppm variation in foraminiferal ba contents between the three basins is consistent with the trend in surface seawater ba the calculated distribution coefficient for ba incorporation in these five species based on these data is 0 19 0 05 several species of the non spinose planktonic foraminifera globorotalia have ba ca ratios ranging from 2 to 13 mol mol these high ba contents might be explained by differences in the way these foraminifera precipitate their shells a temporal record of ba ca in samples of globigerinoides and orbulina from a core in the northwest atlantic suggests that the ba concentration of surface waters at this site has not changed by more than 20 over the last 14 kyr

speed and evolution of nonlinear internal waves transiting the south china sea abstract in the south china sea scs 14 nonlinear internal waves are detected as they transit a synchronous array of 10 moorings spanning the waves generation site at luzon strait through the deep basin and onto the upper continental slope 560 km to the west their arrival time speed width energy amplitude and number of trailing waves are monitored waves occur twice daily in a particular pattern where larger narrower a waves alternate with wider smaller b waves waves begin as broad internal tides close to luzon strait s two ridges steepening to o 3 10 km wide in the deep basin and o 200 300 m on the upper slope nearly all waves eventually develop wave trains with larger steeper waves developing them earlier and in greater numbers the b waves in the deep basin begin at a mean speed of 5 greater than the linear mode 1 phase speed for semidiurnal internal waves computed using climatological and in situ stratification the a waves travel 5 10 faster than b waves until they reach

planktic foraminiferal dissolution in the twilight zone abstract calcite dissolution of planktic foraminifers that settle from the surface ocean to depths has been assessed using the weight size relationship of tests and correlated to carbonate ion concentration co 3 2 of ambient sea water globigerina bulloides and globigerinita glutinata were sampled from the north atlantic and the arabian sea during different seasons spring and fall and the monsoons respectively test weight has been determined for single tests from narrow size classes 250 8 m and 300 7 m minimum test diameter initial test weight of both species in surface waters differs between regions and seasons weight loss of settling tests in the twilight zone between 100 and 1000 m water depths averaged 19 below the twilight zone 1000 2500 m no weight loss occurs on average and tests may even gain weight remineralization of settling planktic foraminiferal tests is most pronounced at maximum co 3 2 accordingly strong dissolution occurs in the twilight zone at the depth of maximum decrease in co 3 2 it is assumed that dissolution of planktic foraminiferal calcite is caused by co 3 2 under saturation inside the test buffered by diffusive exchange of co 3 2 ions with the ambient sea water through the pores and aperture consequently reconstruction of small scale differences in seawater co 3 2 from test weight alone is not feasible and systematic correlation between test weight and co 3 2 of the ambient sea water is statistically not significant at constant co 3 2 remineralization cannot be deduced from test weight neither at high nor low co 3 2 saturation in total our data suggest that the global vertical planktic foraminiferal caco 3 flux is about 19 lower than calculated by schiebel 2002 planktic foraminiferal sedimentation and the marine calcite budget global biogeochemical cycles 16 4 1065 doi 10 1029 2001gb001459

the generation and evolution of nonlinear internal waves in the deep basin of the south china sea abstracttime series observations of nonlinear internal waves in the deep basin of the south china sea are used to evaluate mechanisms for their generation and evolution internal tides are generated by tidal currents over ridges in luzon strait and steepen as they travel west subsequently generating high frequency nonlinear waves although nonlinear internal waves appear repeatedly on the western slopes of the south china sea their appearance in the deep basin is intermittent and more closely related to the amplitude of the semidiurnal than the predominant diurnal tidal current in luzon strait as the internal tide propagates westward it evolves under the influence of nonlinearity rotation and nonhydrostatic dispersion the interaction between nonlinearity and rotation transforms the internal tide into a parabolic or corner shape a fully nonlinear two layer internal wave model explains the observed characteristics of internal tide evolution in the deep basin for different representative forcing cond

ecological analysis of benthic ostracods in the northern japan sea based on water properties of modern habitats and late cenozoic fossil records abstract the ecology of ostracods in the northern japan sea is well documented these ostracods can be grouped in two assemblages 1 the tsushima warm current surface water assemblage twsa northern which lives in an environment where summer temperatures reach up to about 20 c winter temperatures up to about 5 c several species in this assemblage e g loxoconcha optima and pontocythere subjaponica tolerate seasonally low temperatures and lived in the region since the early pleistocene 2 the japan sea intermediate proper water assemblage jsi pa which lives at greater depths lower shelf to upper slope this assemblage lives under stable conditions with a small annual range in temperature 0 5 c the assemblage has a relatively low diversity contains species such as acanthocythereis dunelmensis and robertsonites spp and has been present in the area since the pliocene these data indicate that the presently living species either tolerate seasonally low temperatures twsa northern or tolerate stable but very low temperatures near 0 c and therefore they could survive the pleistocene environmental fluctuations in the japan sea caused by glacio eustatic changes in sea level our data document the survival of ostracod species during past climate change and thus can be used to speculate on the effect of possible future climate change on the faunas we predict that some of the cryophilic species in the japan sea cannot be expected to survive global warming for more than 2 centuries

thermally anomalous assemblages revisited patterns in the extraprovincial latitudinal range shifts of pleistocene marine mollusks pleistocene faunas of the eastern pacific shelf are characterized by thermally anomalous species assemblages i e coexisting species that inhabit different climatic regimes today we used data on the latitudinal ranges of 2887 extant molluscan species to determine the biological basis of the pleistocene faunal migrations overall the species exhibiting the most extensive range shifts termedextraprovincialspecies werenotdrawnrandomlyfromthe availablespeciespool andthepatternisclimaticallyasymmetrical the latitudinal ranges of southern extraprovincial species are significantly wider on average than those of the species pool from whichtheyweredrawn buttherangesofnorthernextraprovincials resemble those of their parent pool this contrast is primarily a consequence of the biogeographic structure of the eastern pacific fauna water massboundariesaremoreeffectivebarriersforsouthern species migrating north in response to changing climatic conditions than for northern species moving south our analysis of pleistocenemarinemollusksprovidesabiologicalandenvironmental context for species response to environmental change and permits predictions about the movement of eastern pacific species relative to major environmental barriers in the face of future global change

observation of the dissolution process of globigerina bulloides tests planktic foraminifera by x ray microcomputed tomography we performed a 9 day dissolution experiment with tests of the planktic foraminifer globigerina bulloides at ph 6 7 0 1 in water undersaturated with respect to calcite the initial stage of the dissolution process which is not recognizable from the surface structure of the tests was quantitatively evaluated by x ray microcomputed tomography xmct xmct revealed three distinct test structures early developed calcite formed during the juvenile stage of g bulloides an inner calcite layer and an outer calcite layer the test ultrastructure was observed by scanning electron microscopy and ct number evaluated the density distribution in the test the early developed calcite and inner calcite layer had low ct numbers 500 1300 low density porous and were sensitive to dissolution whereas the outer calcite layer had high ct numbers 1300 high density and resisted dissolution both the modes and the frequencies of the ct numbers decreased with progress of dissolution changes in the ct number histogram with progress of dissolution were quantified in terms of the percentage of calcite volume accounted for by low density calcite low ct number calcite a clear linear relationship r2 0 87 between low ct number calcite and test weight loss was found this relationship indicates that the amount of test dissolution can be estimated from the distribution of ct numbers we propose that xmct measurements will be useful for quantitatively estimating the amount of carbonate loss from foraminiferal tests by dissolution

seasonal and intraseasonal thermocline variability in the central south china sea seasonal and intraseasonal variability of thermo cline and relative surface height in the central south china sea scs are investigated using time series data of tem perature from three buoys and sea surface height anomaly data from topex poseidon and ers 1 ers 2 satel lites t p ers from feb 1998 through mar 1999 we found that the thermocline becomesdeeper and thinner in winter owing to a great loss of the heat on the sea surface thisfeature ismore evident in the northern than the s outh ern part of the central scs the intraseasonal variation of the thermocline ismainly controlled by the geos trophic vor ticity and is out of phase with sea surface height ssh fur thermore we find a double thermocline phenomenon occurs in the scs in spring owing to maximum net downward heat flux at the surface with the new thermocline appear ing above 80 m and the old thermocline keeping under 80 m deep

application of secondary ion mass spectrometry to the determination of mg ca in rare delicate or altered planktonic foraminifera examples from the holocene paleogene and cretaceous 1 secondary ion mass spectrometry sims is useful for measuring mg ca in both primary calcite and diagenetic minerals in planktonic foraminifera the excellent spatial resolution 10 m and small amount of material removed 2 ng makes it easy to avoid targets that include obvious embedding material and encrusting or infilling minerals such as secondary calcite and authigenic clays in diagenetically altered samples because analyses can be performed on individuals sims is also a viable technique for generating mg ca values from sediment samples in which foraminifera are rare or have low mass for clean primary calcite samples mg ca ratios from sims compare well to those obtained using inductively coupled plasma mass spectrometry icp ms while maintaining information regarding the true variability of elemental ratios within individual tests for samples with secondary calcite or stubbornly adhering clays sims enables us to accurately measure primary calcite compositions and to assess and reconcile contamination problems in bulk samples analyzed by solution based icp ms we have observed that sims is an invaluable and reliable tool for the identification and avoidance of problems of diagenesis and the analysis of rare or delicate planktonic foraminifera however because of operator time required to properly target delicate thin walled or contaminated planktonic foraminifera sims may not be feasible for mg ca studies where large numbers hundreds of samples must be processed and bulk measurements on multiple individuals will suffice

late miocene and pliocene ostracoda from the shimajiri group kume jima island japan biogeographical significance of the timing of the formation of back arc basin okinawa trough abstract the shimajiri group sporadically distributed in kume jima island okinawa prefecture japan is mainly formed from clastic sediments deposited during the late miocene 7 8 7 2 ma the maja formation and the middle pliocene about 3 2 ma the aka formation twenty one samples of these sediments were taken from the maja and the aka formations of the 102 ostracod species recorded most of them are well known on the japanese mainland today three ostracod biofacies were delineated using q mode cluster analysis modern analog technique mat was used to infer the environment during the deposition of the shimajiri group the maja formation was deposited in a littoral temperate environment near the land mass situated to the east of the continent of asia the aka formation was deposited in the temperate shallow sea in front of the delta which protrudes from the vast continental delta faced deep sea the depositional environment of the aka and the maja formations is very closely correlated with the first stage of the formation of the okinawa trough this did not increase in depth until the middle pliocene

evolution of nonlinear internal waves in the east and south china seas synthetic aperture radar sar images from ers i have been used to study the characteristics of internal waves northeast and south of taiwan in the east china sea and east of hainan island in the south china sea rank ordered packets of internal solitons propagating shoreward from the edge of the continental shelf were observed in the sar images on the basis of the assumption of a semidiurnal tidal origin the wave speed can be estimated and is consistent with the internal wave theory by using the sar images and hydrographic data internal waves of elevation have been identified in shallow water by a thicker mixed layer as compared with the bottom layer on the continental shelf the generation mechanism includes the influences of the tide and the kuroshio intrusion across the continental shelf for the formations of elevation internal waves the effects of water depth on the evolution of solitons and wave packets are modeled by the nonlinear kortweg devries kdv type equation and linked to satellite image observations the numerical calculations of internal wave evolution on the continental shelf have been performed and compared with the sar observations for a case of depression waves in deep water the solitons first disintegrate into dispersive wave trains and then evolve to a packet of elevation waves in the shallow water area after they pass through a turning point of approximately equal layer depths that has been observed in the sar image and simulated by the numerical model the importance of the dissipation effect in the coastal area is also discussed and demonstrated

micron scale intrashell oxygen isotope variation in cultured planktic foraminifers abstract in this study we show that the rate of shell precipitation in the extant planktic foraminifer orbulina universa is sufficiently rapid that 12 h calcification periods in 18 o labeled seawater can be resolved and accurately measured using secondary ion mass spectrometry sims for in situ 18 o analyses calcifying o universa held at constant temperature 22 c were transferred every 12 h between ambient seawater 18 o w 0 4 vsmow and seawater with enriched barium and 18 o w 18 6 vsmow to produce geochemically distinct layers of calcite separated by calcite precipitated with an ambient geochemical signature we quantify the position of the ba labeled calcite in the shell wall of o universa via laser ablation icp ms depth profiling of trace element ratios and then measure intrashell 18 o calcite in the same shells using sims with a 3 m spot and an average precision of 0 6 2 sd measured 18 o calcite values in o universa shell layers are within 1 1 of predicted 18 o calcite values elemental and oxygen isotope data show that la icp ms and sims measurements can be cross correlated within the spatial resolution of the two analytical techniques and that 18 o calcite and elemental tracers appear to be precipitated synchronously with no measurable spatial offsets these results demonstrate the capability of sims to resolve daily growth increments in foraminifer shells and highlight its potential for paleoceanographic and biomineralization applications on microfossils

observation of internal wave polarity conversion generated by a rising tide the observations reported here are based on time series of in situ observation data in laoshan bay off the qingdao coast a chain of thermistors t chain at a fixed location recorded a sequence of elevation internal waves followed by depression internal waves passing by over an elapsed time of about 1 h this observed polarity conversion at a fixed location is caused by the vertical stratification variation mainly induced by the rising tide which is believed to be the first reported observation of this kind the process of an elevation internal wave train converting to a depression wave train is simulated using the variable coefficient extended korteweg de vries vekdv equation which also provides a further comparison between theory and the reported observations

characterization of mg ca distributions in planktonic foraminifera species by electron microprobe mapping 1 the distribution of mg ca within the tests of eight modern planktonic foraminifer species has been characterized using electron microprobe mapping species include several that are commonly used for estimation of past seawater temperatures globigerinoides ruber g sacculifer neogloboquadrina incompta synonym of n pachyderma dex n dutertrei and g truncatulinoides each of the investigated species displays large variations in mg ca composition within individual tests however the pattern of mg ca variation is notably different between symbiont bearing and symbiont free species in symbiotic species cyclic mg ca compositional banding occurs that is characterized by narrow 1 3 m high mg ca typically 8 11 mmol mol bands intercalated between broader low mg ca typically 1 5 mmol mol bands this factor of 2 3 difference equates to an apparent calcification temperature change of 10 c or more such temperature changes are considered highly improbable and suggest vital effects significantly modify the incorporation of mg ca into the tests of symbiont bearing species these vital effects remain poorly understood and demand further careful evaluation as they may need to be accounted for when making reliable reconstructions of past oceanic temperatures symbiont free species typically have fewer and broader compositional bands that may reflect more closely changes in calcification temperature as these species migrate within a water column

sea level changes and water structures between 3 5 and 2 8 ma in the central part of the japan sea borderland analyses of fossil ostracoda from the pliocene kuwae formation central japan abstract middle pliocene ostracode assemblages were examined in the lower to middle parts of the kuwae formation central japan ca 3 5 2 8 ma this formation accumulated in the japan sea which is an enclosed marginal sea between the eurasian continent and the islands of japan and is now connected to the open sea through its northern and southern straits q mode factor analysis shows that paleobathymetric changes occurred in orbital obliquity cycles of about 41 kyr at least seven cycles of sea level changes were found in the lower to uppermost parts of the study section from ca 3 2 to 3 0 3 1 ma there was no inflow of temperate intermediate waters due to cooling in japan even in the periods of high interglacial sea levels cyclic changes in the dominance of shallow water ostracodes and deep cool water ostracodes living at a bottom water temperature of 2 5 c are apparent in this interval from ca 3 0 3 1 to 2 8 ma temperate intermediate waters entered the japan sea during each interglacial period the tsushima warm current less than 60 m thick certainly flowed into the japan sea from the southern strait to a small extent during at least 2 88 2 95 ma which is possibly equivalent to marine oxygen isotope stage g15 reflecting high global sea levels krithe antisawanensis which lives abundantly in muddy bottoms at water temperatures of about 6 20 c flourished in these interglacial periods the water temperatures in the lower sublittoral to upper bathyal zones of the japan sea were higher and the thermal gradients there were gentler than they are today suggesting no development of the homogeneous cold water mass like the japan sea intermediate proper water in these periods stable deep water ostracode species were strongly influenced by the inflows of the temperate intermediate waters