Science.gov

Sample records for ostracod cypris subglobosa

  1. Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC(50) values of other test models.

    PubMed

    Khangarot, B S; Das, Sangita

    2009-12-30

    The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48h of 50% of immobilization (EC(50)) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC(50) values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r(2)) for 17 physicochemical properties of metals or metal ions and EC(50)s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK(sp)), softness parameter and some other physicochemical characteristics were significantly correlated with EC(50)s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC(50)s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems. PMID:19683870

  2. Origin of Livistona chinensis var. subglobosa (Arecaceae) on the "islet of the gods": Aoshima, Japan.

    PubMed

    Yoshida, N; Nobe, R; Ogawa, K; Murooka, Y

    2000-07-01

    RAPD analysis was performed to discuss the origin of Livistona chinensis var. subglobosa using samples from eight localities, Iriomotejima, Ishigakijima, Okinawa, Yakushima, Tanegashima, Cape Sata, Tsukishima, and Aoshima, in Japan. Random amplified polymorphic DNA (RAPD) markers were obtained using five random primers and analyzed by the unweighted pair group method arithmetic (UPGMA). Data from Iriomotejima clustered with data from Aoshima, suggesting the possibility that seeds or green woods were carried by the tidal current from the southern fields of Iriomotejima to Aoshima. PMID:10898784

  3. Bromeliad treefrogs as phoretic hosts of ostracods

    NASA Astrophysics Data System (ADS)

    Sabagh, Leandro T.; Rocha, Carlos F. D.

    2014-06-01

    Aquatic organisms can use many methods of dispersal among discrete freshwater habitats, and phoresy is an important but poorly understood mechanism. Tank bromeliads are small and unconnected habitats used by many animals, and some of them use phoresy for dispersal. Ostracods living in bromeliads used treefrogs as phoretic hosts for dispersal. We investigated the distribution of phoretic ostracods among body parts of treefrogs ( Scinax littoreus and Scinax perpusillus), the prevalence and intensity of ostracods ( Elpidium sp.) between Scinax species, and the prevalence and mean intensity of ostracods among the frogs in wet vs. dry seasons in two inselbergs areas at Rio de Janeiro State (Brazil). There were significant differences among the body parts occupied by ostracods and between the Scinax species. Seasonal differences were found only for S. littoreus showing greater abundance during the wet season. Additionally, we record Scinax cuspidatus and Thoropa miliaris as new phoretic hosts for Elpidium sp. to use phoresy.

  4. Bromeliad treefrogs as phoretic hosts of ostracods.

    PubMed

    Sabagh, Leandro T; Rocha, Carlos F D

    2014-06-01

    Aquatic organisms can use many methods of dispersal among discrete freshwater habitats, and phoresy is an important but poorly understood mechanism. Tank bromeliads are small and unconnected habitats used by many animals, and some of them use phoresy for dispersal. Ostracods living in bromeliads used treefrogs as phoretic hosts for dispersal. We investigated the distribution of phoretic ostracods among body parts of treefrogs (Scinax littoreus and Scinax perpusillus), the prevalence and intensity of ostracods (Elpidium sp.) between Scinax species, and the prevalence and mean intensity of ostracods among the frogs in wet vs. dry seasons in two inselbergs areas at Rio de Janeiro State (Brazil). There were significant differences among the body parts occupied by ostracods and between the Scinax species. Seasonal differences were found only for S. littoreus showing greater abundance during the wet season. Additionally, we record Scinax cuspidatus and Thoropa miliaris as new phoretic hosts for Elpidium sp. to use phoresy. PMID:24796544

  5. Origin of fan palm (Livistona chinensis R. Br. var. subglobosa Becc.) in Aoshima, Japan.

    PubMed

    Yoshida, N; Nobe, R; Yamada, T; Ogawa, K; Murooka, Y

    2000-01-01

    RAPD and RFLP analyses were carried out to determine the origin of Livistona chinensis R. Br. var. subglobosa Becc. from Iriomotejima, Ishigakijima, Okinawa, Yakushima, Tanegashima, Cape Sata, Cape Toi, Tsukishima, and Aoshima, Japan. RAPD data obtained using 5 random primers were clustered using UPGMA or the neighbor-joining method. Each population was classified into three clusters based on the phylogenetic tree. L. chinensis plants from Yakushima, Tanegashima and Cape Sata belonged to the isologous cluster, and those from Ishigakijima and Okinawa are contained in a different cluster. L. chinensis from Okinawa and Ishigakijima could be differentiated by being the oldest based on the genetic distance. The area that covers Ishigakijima and Okinawa is thought to be the origin of L. chinensis. L. chinensis plants from Iriomotejima were contained in the same cluster as those from Aoshima. The phylogenetic trees constructed by both RAPD and RFLP analyses indicate the possibility that seeds or green woods of L. chinensis were dispersed by tidal current from the south field around Irlomotejima, and they were washed to Aoshima and established gradually. Therefore, we support the drifting-ashore-naturalized-plant hypothesis on the origin of L. chinensis in Aoshima. PMID:16232888

  6. Biogeography of marine podocopid ostracodes in Micronesia

    USGS Publications Warehouse

    Weissleader, L.S.; Gilinsky, N.L.; Ross, R.M.; Cronin, T. M.

    1989-01-01

    Bottom lagoonal sediment samples from 12 islands and atolls yielded >70 species representing >32 ostracode genera. All or most samples from a particular lagoon generally form distinct subgroups (Jaccard =0.45-0.50). At lower levels, 5 groups delineate faunal regions within Micronesia: the Gilbert Islands (Onotoa) in the SE part of the region, the N Marshall Islands (Enewetak, Rongelap, Bikini), the SE Marshall Islands (Kwajalein, Jaluit, Majuro, Arno), the Marianas and Caroline Islands (Guam, Truk, Pohnpei) and Pingelap. Pingelap, Kwajalein and Onotoa have the highest species richness (S=32-42) and Shannon-Wiener diversity values (H(S)=2.62-3.02) in the study area. Enewetak, Jaluit, Majuro and Arno show lower values (S=23-27, H(S)=2.29-2.70). Of the ostracode species living in Micronesia, 64.3% have Indo-West Pacific affinities, 7.1% are circumtropical, 5.7% have East Pacific-Caribbean affinities, 11.4% are endemic to Micronesia, and 11.4% have unknown affinities. If the SE Asian region is a primary species-source, results show that each Micronesian lagoon is equally likely to be colonized by dispersal from the source region, despite differences in distance from a hypothetical source. However, each lagoon has a distinct ostracode assemblage, probably the result of unique history of random colonization events, local extinctions and environmental disturbances. -from Authors

  7. Controls on ostracod valve geochemistry, Part 1: Variations of environmental parameters in ostracod (micro-)habitats

    NASA Astrophysics Data System (ADS)

    Decrouy, Laurent; Vennemann, Torsten Walter; Ariztegui, Daniel

    2011-11-01

    The variations of environmental conditions ( T°, pH, δ 13C DIC, [DIC], δ 18O, Mg/Ca, and Sr/Ca) of ostracod habitats were examined to determine the controls of environmental parameters on the chemical and isotopic composition of ostracod valves. Results of a one-year monitoring of environmental parameters at five sites, with depths of between 2 and 70 m, in Lake Geneva indicate that in littoral to sub-littoral zones (2, 5, and 13 m), the chemical composition of bottom water varies seasonally in concert with changes in temperature and photosynthetic activity. An increase of temperature and photosynthetic activity leads to an increase in δ 13C values of DIC and to precipitation of authigenic calcite, which results in a concomitant increase of Mg/Ca and Sr/Ca ratios of water. In deeper sites (33 and 70 m), the composition of bottom water remains constant throughout the year and isotopic values and trace element contents are similar to those of deep water within the lake. The chemical composition of interstitial pore water also does not reflect seasonal variations but is controlled by calcite dissolution, aerobic respiration, anaerobic respiration with reduction of sulphate and/or nitrate, and methanogenesis that may occur in the sediment pores. Relative influence of each of these factors on the pore water geochemistry depends on sediment thickness and texture, oxygen content in bottom as well as pore water. Variations of chemical compositions of the ostracod valves of this study vary according to the specific ecology of the ostracod species analysed, that is its life-cycle and its (micro-)habitat. Littoral species have compositions that are related to the seasonal variations of temperature, δ 13C values of DIC, and of Mg/Ca and Sr/Ca ratios of water. In contrast, the compositions of profundal species are largely controlled by variations of pore fluids along sediment depth profiles according to the specific depth preference of the species. The control on the

  8. Ostracod Body Size Change Across Space and Time

    NASA Astrophysics Data System (ADS)

    Nolen, L.; Llarena, L. A.; Saux, J.; Heim, N. A.; Payne, J.

    2014-12-01

    Many factors drive evolution, although it is not always clear which factors are more influential. Miller et al. (2009) found that there is a change in geographic disparity in diversity in marine biotas over time. We tested if there was also geographic disparity in body size during different epochs. We used marine ostracods, which are tiny crustaceans, as a study group for this analysis. We also studied which factor is more influential in body size change: distance or time. We compared the mean body size from different geologic time intervals as well as the mean body size from different locations for each epoch. We grouped ostracod occurrences from the Paleobiology Database into 10º x 10º grid cells on a paleogeographic map. Then we calculated the difference in mean size and the distance between the grid cells containing specimens. Our size data came from the Ellis & Messina"Catalogue of Ostracod" as well as the"Treatise on Invertebrate Paleontology". Sizes were calculated by applying the formula for the volume of an ellipsoid to three linear dimensions of the ostracod carapace (anteroposterior, dorsoventral, and right-left lengths). Throughout this analysis we have come to the realization that there is a trend in ostracods towards smaller size over time. Therefore there is also a trend through time of decreasing difference in size between occurrences in different grid cells. However, if time is not taken into account, there is no correlation between size and geographic distance. This may be attributed to the fact that one might not expect a big size difference between locations that are far apart but still at a similar latitude (for example, at the equator). This analysis suggests that distance alone is not the main factor in driving changes in ostracod size over time.

  9. Ostracods from the Neogene Solimões Formation (Amazonas, Brazil)

    NASA Astrophysics Data System (ADS)

    Feijó Ramos, Maria Inês

    2006-03-01

    Ostracods from an outcrop of the Solimões Formation (southwestern Amazonas state, Brazil) are studied. One new species ( Cytheridella purperae sp. nov. ) is described, and six species endemic to the Neogene of western Amazonia ( Darwinula fragilis, Cyprideis pebasae, C. graciosa, C. longispina, C. lacrimata, and Cypria aqualica) are reported, together with one unidentified species ( Cytheridella sp.). The fauna suggest a low-energy fluviolacustrine depositional setting, possibly with very low salinity. Using facies and ostracod data, the studied outcrop is compared with other Miocene deposits of western Amazonia.

  10. Early irrigation systems in southeastern Arizona: the ostracode perspective

    NASA Astrophysics Data System (ADS)

    Palacios-Fest, Manuel R.; Mabry, Jonathan B.; Nials, Fred; Holmlund, James P.; Miksa, Elizabeth; Davis, Owen K.

    2001-10-01

    For the first time, the Early Agricultural Period (1200 BC-150 AD) canal irrigation in the Santa Cruz River Valley, southeastern Arizona, is documented through ostracode paleoecology. Interpretations based on ostracode paleoecology and taphonomy are supported by anthropological, sedimentological, geomorphological, and palynological information, and were used to determine the environmental history of the northern Tucson Basin during the time span represented by the sequence of canals at Las Capas (site AZ AA:12:753 ASM). We also attempt to elucidate based on archaeological artifacts if the Hohokam or a previous civilization built the canals. Between 3000 and 2400 radiocarbon years BP, at least three episodes of canal operation are defined by ostracode assemblages and pollen records. Modern (mid-late 20th century) canals supported no ostracodes, probably because of temporally brief canal operation from local wells. Three stages of water management are well defined during prehistoric canal operation. Ostracode faunal associations indicate that prehistoric peoples first operated their irrigation systems in a simple, 'opportunistic' mode (diversion of ephemeral flows following storms), and later in a complex, 'functional' mode (carefully timed diversions of perennial flows). The geomorphological reconstruction indicates that these canals had a minimum length of 1.1 km, and were possibly twice as long. The hydraulic reconstruction of these canals suggests that they had similar gradients (0.05-0.1%) to later prehistoric canals in the same valley. Discharges were also respectable. When flowing at bank-full, the largest canal provided an acre-foot of water in about 2.3 h; when flowing half-full (probably a more realistic assumption), it produced an acre-foot of water in about 8.6 h. Palynological records of the oldest canals (here identified as Features 3 and 4; 3000-2500 years BP) indicate they were used temporarily, since riparian vegetation did not grow consistently in

  11. On the morphology of antennular sensory and attachment organs in cypris larvae of the deep-sea vent/seep barnacles, Ashinkailepas and Neoverruca.

    PubMed

    Yorisue, Takefumi; Chan, Benny K K; Kado, Ryusuke; Watanabe, Hiromi; Inoue, Koji; Kojima, Shigeaki; Høeg, Jens T

    2016-05-01

    Barnacle cypris larvae show high morphological variation in the organs used in search of and attaching to a substratum. This variation may represent adaptation to the habitat of the species. Here, we studied SEM level morphologies of cypris antennular sensory and attachment organs in a deep-sea vent endemic species (Neoverruca sp.) and a vent/seep inhabiting species (Ashinkailepas seepiophila). We compare them with three species from other environments. The antennular morphologies of Neoverruca sp. and A. seepiophila were similar, which is consistent with recent molecular studies showing a close relationship of the two species. The setation pattern of the antennules was very conservative among species from various environments. In contrast, striking differences were observed in the structure of the attachment organ (the third antennular segment). Neoverruca sp. and A. seepiophila had no velum or a skirt surrounding the attachment disc on the third segment, while other cirripede cyprids almost always have either of these structures. In addition, both cyprids of A. seepiophila and Neoverruca sp. had the attachment disc angled toward the substratum, whereas it faces distally in cyprids from hard bottom inhabiting barnacles. We suggest that both velum/skirt and the angle of the attachment disc play an important role, when the antennules are contacting the substratum during surface exploration. Differences in attachment organ structures may be highly adaptive, enabling cirripede species to enter new habitats during evolution. PMID:26948410

  12. Modern benthic ostracodes from Lutzow-Holm Bay, East Antarctica: paleoceanographic, paleobiogeographic, and evolutionary significance

    USGS Publications Warehouse

    Yasuhara, Moriaki; Kato, Masako; Ikeya, Noriyuki; Seto, Koji

    2007-01-01

    Seventy-three ostracode species from 38 genera were recovered from the 55 surface sediment samples in Lützow-Holm Bay, northeastern Antarctica. We investigated bathymetric and geographic distributions of modern benthic ostracode species in the bay and compared this fauna with published modern and fossil ostracode data of Antarctic and southern South American regions. The results show: (1) Four biotopes and three sub-biotopes are recognized based on Q-mode cluster analysis, which suggest distributions of modern ostracodes are mainly controlled by water-mass structure, ice scouring, and light availability. (2) Comparison between the Lützow-Holm Bay fauna and other ostracode faunas from Antarctica and southern South America shows high endemism and homogeneity of Antarctic ostracode fauna, suggesting in situ evolution of most extant Antarctic species. (3) Most species are endemic to the Antarctica, a few species also inhabit South American waters.

  13. Middle Pleistocene ostracod assemblages from Lake Trasimeno, Perugia (Italy)

    NASA Astrophysics Data System (ADS)

    Marchegiano, Marta; Gliozzi, Elsa; Buratti, Nicoletta; Ariztegui, Daniel; Cirilli, Simonetta

    2014-05-01

    Lake Trasimeno is a meso-eutrophic, shallow (<6 m deep) and large lake (~120km2) located in central Italy, at 259 m above sea level. A preliminary age model based on pollen data for a core retrieved along the present southern shore of the lake (north of the Panicarola town) suggests that the record may be as old as Middle Pleistocene. An ongoing multidisciplinary study of a 175 m long sedimentary core includes magnetic properties, sedimentary microfacies, paleontology, palynology and bulk elemental geochemistry. This contribution focus on the paleoenvironmental reconstruction of the topmost 30 m of the core using ostracods. A total of 245 samples have been taken at a 13 cm sampling interval. On the whole, 13 species referable to 10 genera were collected (Ilyocypris gibba, Candona neglecta, Candona angulata, Cypridopsis vidua, Heterocypris salina, Limnocythere sp.1, Limnocythere stationis, Darwinula stevensoni, Cyprideis sp., Leptocythere spp., Fabaeformiscandona fabaeformis, Cyclocypris ovum). Abrupt changes in the abundance of the assemblages were found along the studied core alternating sections with very abundant ostracod remains with others with scant (or even null) individuals. Moreover, the changes observed in the composition of the ostracod assemblages are interpreted as recording environmental variations. In particular, two intervals are significant for the paleoenvironmental reconstruction of this sedimentary succession: 1) the section from 25.60 m to 23.50 m is characterized by a rich ostracod fauna (dominated by Cyprideis sp., Candona angulata and Leptocythere spp.). These assemblages possibly indicate an increase in salinity or alkalinity of the water body; 2) the interval from 21.05 m to 17.60 m contains Ilyocypris gibba, Candona neglecta, Cypridopsis vidua, Heterocypris salina, Limnocythere sp. 1, Limnocythere stationis and Darwinula stevensoni. Limnocythere stationis is a central European species, until now in Italy only described in the Holocene of

  14. Size Evolution and Stochastic Models: Explaining Ostracod Size through Probabilistic Distributions

    NASA Astrophysics Data System (ADS)

    Krawczyk, M.; Decker, S.; Heim, N. A.; Payne, J.

    2014-12-01

    The biovolume of animals has functioned as an important benchmark for measuring evolution throughout geologic time. In our project, we examined the observed average body size of ostracods over time in order to understand the mechanism of size evolution in these marine organisms. The body size of ostracods has varied since the beginning of the Ordovician, where the first true ostracods appeared. We created a stochastic branching model to create possible evolutionary trees of ostracod size. Using stratigraphic ranges for ostracods compiled from over 750 genera in the Treatise on Invertebrate Paleontology, we calculated overall speciation and extinction rates for our model. At each timestep in our model, new lineages can evolve or existing lineages can become extinct. Newly evolved lineages are assigned sizes based on their parent genera. We parameterized our model to generate neutral and directional changes in ostracod size to compare with the observed data. New sizes were chosen via a normal distribution, and the neutral model selected new sizes differentials centered on zero, allowing for an equal chance of larger or smaller ostracods at each speciation. Conversely, the directional model centered the distribution on a negative value, giving a larger chance of smaller ostracods. Our data strongly suggests that the overall direction of ostracod evolution has been following a model that directionally pushes mean ostracod size down, shying away from a neutral model. Our model was able to match the magnitude of size decrease. Our models had a constant linear decrease while the actual data had a much more rapid initial rate followed by a constant size. The nuance of the observed trends ultimately suggests a more complex method of size evolution. In conclusion, probabilistic methods can provide valuable insight into possible evolutionary mechanisms determining size evolution in ostracods.

  15. Exceptionally preserved 450-million-year-old ordovician ostracods with brood care.

    PubMed

    Siveter, David J; Tanaka, Gengo; Farrell, Una C; Martin, Markus J; Siveter, Derek J; Briggs, Derek E G

    2014-03-31

    Ostracod crustaceans are the most abundant fossil arthropods and are characterized by a long stratigraphic range. However, their soft parts are very rarely preserved, and the presence of ostracods in rocks older than the Silurian period [1-5] was hitherto based on the occurrence of their supposed shells. Pyritized ostracods that preserve limbs and in situ embryos, including an egg within an ovary and possible hatched individuals, are here described from rocks of the Upper Ordovician Katian Stage Lorraine Group of New York State, including examples from the famous Beecher's Trilobite Bed [6, 7]. This discovery extends our knowledge of the paleobiology of ostracods by some 25 million years and provides the first unequivocal demonstration of ostracods in the Ordovician period, including the oldest known myodocope, Luprisca incuba gen. et sp. nov. It also provides conclusive evidence of a developmental brood-care strategy conserved within Ostracoda for at least 450 million years. PMID:24631241

  16. Lower and Middle Devonian Malvinokaffric ostracods from the Precordillera Basin of San Juan, Argentina

    NASA Astrophysics Data System (ADS)

    Salas, María J.; Rustán, Juan J.; Sterren, Andrea F.

    2013-08-01

    Ostracod from the upper Lower to Middle Devonian rocks of the Argentine Precordillera Basin (Talacasto and Punta Negra formations) are studied. One new genus Pircawayra nov. gen., and five species (including three new: Pircawayra gigantea nov. gen. and sp., Lapazites trinodis nov. sp. and Keslingiella? teresae nov. sp.) are defined. The recorded ostracod fauna closely resembles that coeval from Bolivia and South Africa, exhibiting a remarkable endemism, not only at the genus level, but also at the species level. In addition to its low-diversity, the Malvinokaffric ostracod association is also characterized by having large, thick, coarsely ornamented and swollen valves. The similar ostracod composition from the Andean and South African basins suggests faunal exchange between these two areas. Based on the ostracod faunas, the Malvinokaffric Realm is clearly recognizable at least up to the Middle Devonian.

  17. Early Badenian ostracod assemblage of the Židlochovice stratotype(Carpathian Foredeep, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Seko, Michal; Pipík, Radovan; Doláková, Nela

    2012-03-01

    Fifty-two ostracod taxa were identified from two sediment cores collected from the early Badenian Židlochovice stratotype. Ostracod assemblages were analyzed with a focus on taxonomy, paleoecology, distribution of taxa along the sediment cores, quantification of valve/carapace ratios, and species richness by Simpson's Reciprocal Index. The changes in ostracod assemblages identified in these cores reflect a shallowing of the marine water-depth from circalittoral/epibathyal to shallow infralittoral, and an increase in the sedimentation rate upwards through time. A comparison of all Badenian ostracod assemblages in the Carpathian Foredeep indicates a high proportion of deep-water ostracod species in Židlochovice and its surroundings, suggesting that the deepest part of the Carpathian Foredeep was probably situated in this part of the Czech Republic.

  18. Early Mississippian (Tournaisian) ostracodes from the Lisburne test well, northern Alaska

    SciTech Connect

    Sohn, I.G.

    1989-01-01

    Anita G. Harris processed limestone sample 27660-PC, core 18, from a depth of 4968.84 to 4970.98 m in the Lisburne No. 1 test well, National Petroleum Reserve in Alaska, and recovered poorly preserved silicified ostracodes. The well is located in the disturbed belt, SE{1/4} sec. 17, T. 11 S., R. 16 W., lat 68{degree}29 0.54381, long 155{degree}41 35.510. A crushed duplicate sample from a depth of 4968.84 to 4970.37 m yielded a few unidentifiable fragments and steinkerns and one carapace of Microcheilinella Geis, 1933. The crushed limestone was dissolved in acetic acid, from which the fine material was periodically removed, and yielded additional poorly preserved replaced ostracodes, including some that were not represented in the original sample. The ostracodes indicate a probable Kinderhookian and (or) Osagan age for the rocks. The assemblage differs, on the species level, from congeneric Meramecian ostracodes in the Brooks Range, and there are a few taxa not found in the Meramecian assemblages. In addition to the ostracodes, steinkerns of minute gastropods and pelecypods, brachiopod and echinoderm spines, fish teeth, fragments of bryozoans, and one conodont were recovered. These associated fossils confirm that marine shelf environment indicated by the ostracodes: Because of poor preservation and meager representation of conspecific specimens, the ostracodes are illustrated in open nomenclature. The presently known stratigraphic ranges of the known genera are indicated.

  19. Pleistocene Deep Sea ostracods from the Bering Sea (IODP expedition 323)

    NASA Astrophysics Data System (ADS)

    Alvarez Zarikian, Carlos A.

    2016-03-01

    The study presents the first Pleistocene (0-1.9 Ma) record of Deep Sea ostracods from the Bering Sea, derived primarily from Integrated Ocean Drilling Program Expedition 323, Site U1344 (59°3.0‧N, 179°12.2‧W, 3171 m of water depth). Deep Sea ostracod abundances in the Bering Sea sediments are some of the lowest that have been recorded in bathyal and abyssal marine environments (<1 specimen per sediment gram). In comparison, benthic foraminifera are several orders of magnitude more abundant in the same samples. The humble ostracod assemblage at Site U1344 is predominantly composed of deep water species Krithe sawanensis, Fallacihowella sp. A, Cytheropteron spp., Eucytherura sp., Argilloecia toyamaensis, and Bradleya mesembrina. Less abundant taxa include Munseyella melzeri, Munseyella ristveti, Cluthia sp., Robertsonites hanaii, and Microcythere mediostriata. Some of these taxa (e.g. Fallacihowella sp. A, Bradleya mesembrina, Microcythere mediostriata) are reported for the first time in the North Pacific. The predominance of the genera Krithe, Fallacihowella, Cytheropteron and Argilloecia indicates cold, ventilated bottom waters. The deep Bering Sea ostracod assemblage shares many common and closely related species with continental slope faunas from the Gulf of Alaska, the Okhotsk Sea, the Arctic Ocean, and even the subpolar North Atlantic. A few continental shelf ostracods, such as species of Munseyella and Robertsonites, are present at Sites U1344 and U1343, in the northern slope of the Aleutian Basin. The presence of shallow water ostracods at the Bering Sea slope sites is possibly explained by sea ice rafting. Exceptionally low ostracod abundance in the U1344 record did not permit evaluating links between ostracod faunas and paleoceanographic conditions; however, an increase in ostracod occurrences throughout the middle Pleistocene at Site U1344 appears to correlate with general sea ice expansion in the Bering Sea. High primary surface productivity, high

  20. An environmental tolerance index for ostracodes as indicators of physical and chemical factors in aquatic habitats

    USGS Publications Warehouse

    Curry, B. Brandon

    1999-01-01

    Continental ostracode occurrences reflect salinity, solute composition, temperature, flow conditions, and other environmental properties of the water they inhabit. Their occurrences also reflect the variability of many of these environmental parameters. Environmental tolerance indices (ETIs) offer a new way to express the nature of an ostracode's environment. As defined herein, ETIs range in value from zero to one, and may be calculated for continuous and binary variables. For continuous variables such as salinity, the ETI is the ratio of the range of values of salinity tolerated by an ostracode to the total range of salinity values from a representative database. In this investigation, the database of continuous variables consists of information from 341 sites located throughout the United States. Binary ETIs indicate whether an environmental variable such as flowing water affects ostracode presence or absence. The binary database consists of information from 784 sites primarily from Illinois, USA. ETIs were developed in this investigation to interpret paleohydrological changes implied by fossil ostracode successions. ETI profiles may be cast in terms of a weighted average, or on presence/absence. The profiles express ostracode tolerance of environmental parameters such as salinity or currents. Tolerance of a wide range of values is taken to indicate shallow water because shallow environments are conducive to thermal variability, short-term water residence, and the development of currents from wind-driven waves.

  1. Relationship Between the Surface Area to Volume Ratio and Temperature across Geologic Time in Ostracods

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Zaroff, S.; Heim, N. A.; Payne, J.

    2014-12-01

    In 1877 Joseph Allen proposed that endothermic terrestrial organisms would have lower surface area to volume ratios (SAVR) in colder climates and higher SAVRs in warmer climates. With a smaller surface area compared to volume, organisms can retain more heat in cold climates. We tested to see if this principle applied to ostracods, a type of ectothermic marine invertebrate. We hypothesised that Allen's rule applies to ostracods, as Allen's rule has been demonstrated in frogs (Alho 2011), which are also ectotherms . We used the linear dimensions of the three major carapace axes of ostracod holotypes to estimate the SAVR. We compared ostracod SAVRs with paleotemperatures from Royer et al. (2004). We found that there was a correlation between surface area and temperature; it is a small, but statistically significant correlation (adj. R2=0.0167). This means that as temperature increased, the SAVR also increased. We also found a negative correlation between ostracod SAVR to geologic time(adj. R2=0.0114), which shows us that as time has gone on, ostracod SAVR has decreased. We then plotted the correlation coefficient of SAVR to temperature over geologic time to explore trends in the strength of Allen's rule. For most of time there was no relationship but during the Devonian, Allen's Rule did explain the trend. In short, temperature does explain some of the correlation between the SAVR and temperature, but it is likely there were other environmental factors affecting this relationship.

  2. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development

    PubMed Central

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A.; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R.

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  3. Toxicity of Metals to a Freshwater Ostracod: Stenocypris major

    PubMed Central

    Shuhaimi-Othman, Mohammad; Yakub, Nadzifah; Ramle, Nur-Amalina; Abas, Ahmad

    2011-01-01

    Adults of freshwater ostracod Stenocypris major (Crustacea, Candonidae) were exposed for a four-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al), and manganese (Mn) concentrations. Mortality was assessed, and median lethal times (LT50) and concentrations (LC50) were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively, for all metals. LC50s for 96 hours for Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 25.2, 13.1, 1189.8, 526.2, 19743.7, 278.9, 3101.9, and 510.2 μg/L, respectively. Metals bioconcentration in S. major increases with exposure to increasing concentrations, and Cd was the most toxic to S. major, followed by Cu, Fe, Mn, Pb, Zn, Al, and Ni (Cd>Cu>Fe>Mn>Pb>Zn>Al>Ni). Comparison of LC50 values for metals for this species with those for other freshwater crustacean reveals that S. major is equally or more sensitive to metals than most other tested crustacean. PMID:21559091

  4. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development.

    PubMed

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  5. Ostracode Mg/Ca Paleothermometry: Applications and Complications

    NASA Astrophysics Data System (ADS)

    Cronin, T. M.; Dwyer, G. S.

    2007-12-01

    Ostracode (bivalved Crustacea) shell Mg/Ca paleothermometry has wide applicability in Cenozoic paleoclimatology over 101 to 107 year timescales because they are commonly fossilized, live in freshwater, shallow- and deep-marine habitats, and grow by molting, which minimizes Mg/Ca variability due to ontogenetic variability. Two empirically derived Mg/Ca-temperature calibrations based on core top and culturing include one for the shallow marine, estuarine genus Loxoconcha (5 to 30°C) and another for deep-sea genus Krithe (<1 to 14°C). The former produced a temperature history for Chesapeake Bay for the last millennium, which has been intensively analyzed in the context of the hockey stick temperature curve. The latter produced evidence for decreased deep-sea temperature during glacial intervals and the first Atlantic-wide reconstruction of deep-sea temperature during the warm mid-Pliocene. In addition to temperature, however, factors such as host-water magnesium concentrations, salinity, intra-shell, intra-population, and interspecific variabilility, seasonality, biological factors (shell secretion rate), and post-mortem dissolution can contribute to scatter in calibration datasets and uncertainty in paleotemperature estimates. We will review these processes, present a new 2000 year Chesapeake temperature record, and discuss its relation to twentieth century climate change.

  6. Lake Michigan's late Quaternary limnological and climate history from ostracode, oxygen isotope, and magnetic susptibility

    USGS Publications Warehouse

    Forester, Richard M.; Colman, Steven M.; Reynolds, Richard L.; Keigwin, Loyd D.

    1994-01-01

    The limnology of Lake Michigan has changed dramatically since the late Pleistocene in response to the expansion and contraction of continental glaciers, to differential isostatic rebound, and to climate change. The lake sediment's stratigraphic trends, magnetic susceptibility, δ18O, and ostracode species abundance ratios provide criteria to identify the lake's response to glacial ice and to differential isostatic rebound. The latter phenomena dominate the lake's late Pleistocene and early Holocene history. The lake's hydrological budget provides the primary linkage between the lake and climate, particularly effective moisture. Dissolved salts were stored in the lake's water column when the lake's output shifted toward evaporation, but were flushed when output shifted toward outflow. The lake's salt storage history may be interpreted from some ostracode, δ18O, and magnetic susceptibility records found in sediment cores. Climate change influenced the entire lake's limnological history, but became the primary limnological driver from about the middle-Holocene to the present. The complex limnological history of Lake Michigan resulted in substantial changes in the ostracode species assemblages; from about 12,000 ka to about 5,500 ka, five ostracode intervals can be identified. These ostracode intervals provide a within-lake biostratigraphy and a stratigraphic reference for reconstruction of the paleoenvironmental dynamics of the lake.

  7. Wisconsinan and Sangamonian climate interpreted from fossil ostracodes and vegetation in south-central Illinois

    SciTech Connect

    Curry, B.B. ); Forester, R.M. ); Zhu, Hong; Baker, R.G. . Dept. of Geology)

    1992-01-01

    The interpretation of paleoclimate during the late Illinoian, Sangamonian, and Wisconsinan Ages in the region of present south-central Illinois has been based on plant macrofossil, pollen, and vertebrate records. The ostracode records identify periods of flow across the basins and perhaps characteristics of groundwater discharge or recharge. Basins with the largest lake-to-catchment-area ratio were most sensitive to changes in effective moisture and hydrochemistry. The Sangamonian included three intervals during which the winters were warmer than those of historical record. These intervals are represented by sediment containing relatively abundant arboreal pollen, notably bald cypress and sweet gum, and the ostracode Heterocypris punctata, which lives in subtropical to tropical lakes and estuaries. H. punctata occurs with other ostracodes that require low salinity; their association indicates that precipitation typically exceeded evaporation and that the basin was affected by throughflow. The Sangamonian ended with two warm, wet episodes that sandwich an interval implying prairie lake conditions. Warmth-loving species are abundantly represented in upper Sangamonian sediments. Such warm, wet episodes are not known to have occurred in the Midcontinent during the Holocene. The top of the Sangamonian in all except the Pittsburgh Basin is capped by a layer of reworked sediment containing fluvial ostracodes and exotic mixtures of pollen, including both spruce and sweet gum but dominated by chenopods. The reworked layer is overlain by Wisconsinan sediment containing abundant pollen of boreal taxa and ostracodes that indicate basin throughflow.

  8. A 600-ka Arctic sea-ice record from Mendeleev Ridge based on ostracodes

    USGS Publications Warehouse

    Cronin, Thomas M.; Polyak, L.V.; Reed, D.; Kandiano, E. S.; Marzen, R. E.; Council, E. A.

    2013-01-01

    Arctic paleoceanography and sea-ice history were reconstructed from epipelagic and benthic ostracodes from a sediment core (HLY0503-06JPC, 800 m water depth) located on the Mendeleev Ridge, Western Arctic Ocean. The calcareous microfaunal record (ostracodes and foraminifers) covers several glacial/interglacial cycles back to estimated Marine Isotope Stage 13 (MIS 13, ∼500 ka) with an average sedimentation rate of ∼0.5 cm/ka for most of the stratigraphy (MIS 5–13). Results based on ostracode assemblages and an unusual planktic foraminiferal assemblage in MIS 11 dominated by a temperate-water species Turborotalita egelida show that extreme interglacial warmth, high surface ocean productivity, and possibly open ocean convection characterized MIS 11 and MIS 13 (∼400 and 500 ka, respectively). A major shift in western Arctic Ocean environments toward perennial sea ice occurred after MIS 11 based on the distribution of an ice-dwelling ostracode Acetabulastoma arcticum. Spectral analyses of the ostracode assemblages indicate sea ice and mid-depth ocean circulation in western Arctic Ocean varied primarily at precessional (∼22 ka) and obliquity (∼40 ka) frequencies.

  9. Latest Mississippian (Namurian A) nonmarine ostracodes from West Virginia and Virginia.

    USGS Publications Warehouse

    Sohn, I.G.

    1985-01-01

    Nonmarine ostracodes occur as partly exfoliated carapaces and internal molds at the base of the Bramwell Member of the Bluestone Formation, which represents the uppermost Mississippian (Namurian A), stratigraphic subdivision in West Virginia and Virginia. These specimens are important in that they permit the determination of a variety of adductor-muscle-attachment scars. The adductor-muscle-attachment scar patterns illustrated herein for the first time are the oldest recorded in North America for nonmarine ostracodes. The new family Carbonitidae and superfamily Carbonitacea are established on the basis of the pattern of adductor-muscle-attachment scars. The following nonmarine genera in this unit are illustrated in open nomenclature: Carbonita Strand, 1928; Whipplella? Holland, 1934; Gutschickia Scott, 1944; Pruvostina? Scott and Summerson, 1943; Darwinula Brady and Robertson, 1885; and two steinkerns of geisinid ostracodes, 'Pseudo-ornamentation' on molds is illustrated.-Author

  10. Determination of the dissolved anion composition of ancient lakes from fossil ostracodes.

    USGS Publications Warehouse

    Forester, R.M.

    1986-01-01

    The mineralogy of evaporite and other precipitated minerals has provided traditional sources of information about the major dissolved ion composition of ancient lakes. The paleocompositional resolving power of these methods is generally greatest in high-salinity lakes. Ostracodes live in dilute saline lakes where a species occurrence is determined by the relative proportions of the lake's major dissolved anions, so that each species describes specific areas on an anion trilinear diagram. The upper salinity tolerance of each species depends upon the types of major anions in solution and is therefore anion-specific. Knowledge about both anion and anion-salinity tolerances of an ostracode may ultimately provide a means of estimating absolute anion concentrations in paleolakes. Because ostracodes are common fossils in lake sediments, they provide an important new source of original paleocompositional information suitable for many geologic, climatic, geochemical, and paleontologic studies. -from Author

  11. Upper Neopleistocene ostracods from the southeastern West Siberian Plain and their stratigraphic significance

    NASA Astrophysics Data System (ADS)

    Konovalova, V. A.

    2016-01-01

    In the upper Neopleistocene of the southeastern West Siberian Plain, two ancillary biostratigraphic units by ostracods in the rank of faunal beds, namely, the Cypridopsis vidua-Herpetocypris reptans Beds (Ermakovo Horizon and the lower part of the Karginsky Horizon) and the Ilyocypris pustulata Beds (Karginsky Horizon), are recognized for the first time. The age of the Ilyocypris pustulata Beds is substantiated by a series of radiometric datings. The Eucypris pigra- Cyclocypris laevis- C. triangula ostracod assemblage from the upper part of the Sartan Horizon, whose age is also justified by a radiometric date, is characterized. The new data on ostracods supplement the materials available on this group of fauna and refine the Quaternary regional stratigraphic scheme of the West Siberian Plain.

  12. Environmental Factors Controlling Ostracod Distribution on the Tibetan Plateau and Adjacent Areas

    NASA Astrophysics Data System (ADS)

    Boerner, N.; Pröttel, R.; Glodniok, S.; Söndgerath, D.; Naumann, K.; Frenzel, P.; Mischke, S.; Schwalb, A.

    2014-12-01

    Non-marine ostracods represent a reliable tool to reconstruct past climate conditions. The investigation of environmental tolerances of modern ostracod species is therefore vital to estimate past climate conditions based on fossil assemblages. To determine the climate range of individual ostracod species their modern geographical distribution is combined with climate data sets. The overlap of modern ecological tolerances of ostracod species found in a fossil assemblage yield information about past air temperatures [1]. In our study we establish ecological tolerances of species from the Tibetan Plateau and adjacent areas and indicate which environmental parameter is most important for species distribution. Therefore the point biserial correlation coefficient is applied on the species distribution of 34 taxa from 364 locations based on the presence/absence of species. We use a 0.93 km gridded climate database that pairs climate parameters with modern collection sites. In total we investigated the influence of 20 different environmental parameters, such as annual temperature amplitude, July and January temperatures, precipitation, salinity and altitude. The yearly temperature range is the most important factor defining the distribution for Candona candida and Fabaeformiscandona gyirongensis. The distribution of Eucypris mareotica is also influenced by the yearly temperature range, but in addition is restricted by low salinities. Species showing no correlation to temperature variations in their distribution were also identified. The distribution of Limnocythere inopinata and Heterocypris salina is restricted by the amount of precipitation, especially during winter months, and low salinities. On the other hand, Candona neglectaseems to be unaffected by any of the studied parameters and probably only is limited by extremely high salinities. The calculated mutual climate ranges of the investigated ostracod species will be applied to ostracod assemblage data from a long

  13. Recent shallow marine ostracods from high latitudes: Implications for late Pliocene and Quarternary palaeoclimatology

    USGS Publications Warehouse

    Brouwers, E.M.; Cronin, T. M.; Horne, D.J.; Lord, A.R.

    2000-01-01

    New information about modern high-latitude marine ostracod faunas and about their occurrence in late Pliocene and Quaternary sequences promotes the application of these microfossils to palaeoenvironmental, palaeobiogeographical and palaeoclimatological problems. Five poorly known species (Cluthia cluthae, Finmarchinella logani, Roundstonia globulifera, Roundstonia macchesneyi and Semicytherura complanata) from North Atlantic, North Pacific and Arctic areas are confirmed as extant and are used to demonstrate the potential of marine ostracods as tools for palaeoclimate studies. The genus Bonnyannella Athersuch, 1982 is shown to be a junior synonym of Roundstonia Neale, 1973.

  14. Controls on ostracod valve geochemistry: Part 2. Carbon and oxygen isotope compositions

    NASA Astrophysics Data System (ADS)

    Decrouy, Laurent; Vennemann, Torsten Walter; Ariztegui, Daniel

    2011-11-01

    The stable carbon and oxygen isotope compositions of fossil ostracods are powerful tools to estimate past environmental and climatic conditions. The basis for such interpretations is that the calcite of the valves reflects the isotopic composition of water and its temperature of formation. However, calcite of ostracods is known not to form in isotopic equilibrium with water and different species may have different offsets from inorganic precipitates of calcite formed under the same conditions. To estimate the fractionation during ostracod valve calcification, the oxygen and carbon isotope compositions of 15 species living in Lake Geneva were related to their autoecology and the environmental parameters measured during their growth. The results indicate that: (1) Oxygen isotope fractionation is similar for all species of Candoninae with an enrichment in 18O of more than 3‰ relative to equilibrium values for inorganic calcite. Oxygen isotope fractionation for Cytheroidea is less discriminative relative to the heavy oxygen, with enrichments in 18O for these species of 1.7 to 2.3‰. Oxygen isotope fractionations for Cyprididae are in-between those of Candoninae and Cytheroidea. The difference in oxygen isotope fractionation between ostracods and inorganic calcite has been interpreted as resulting from a vital effect. (2) Comparison with previous work suggests that oxygen isotope fractionation may depend on the total and relative ion content of water. (3) Carbon isotope compositions of ostracod valves are generally in equilibrium with DIC. The specimens' δ 13C values are mainly controlled by seasonal variations in δ 13C DIC of bottom water or variation thereof in sediment pore water. (4) Incomplete valve calcification has an effect on carbon and oxygen isotope compositions of ostracod valves. Preferential incorporation of CO32- at the beginning of valve calcification may explain this effect. (5) Results presented here as well as results from synthetic carbonate

  15. Paleolimnological inferences based on Oligocene ostracods (Crustacea: Ostracoda) from Tremembé Formation, Southeast Brazil.

    PubMed

    Bergue, Cristianini T; Maranhão, Maria da Saudade A S; Fauth, Gerson

    2015-09-01

    Non-marine Oligocene ostracods from Tremembé Formation (Taubaté Basin, Southeast Brazil) are studied for the first time. The study reveals rich assemblages which are probably composed of many new taxa, two of which are described here. The sixteen ostracod species registered are classified in the generaCypretta Vávra, Strandesia Stuhlmann,Potamocypris Brady, Heterocypris Claus,Eucypris Vávra, Herpetocypris Brady and Norman, Cytheridella Daday and LimnocythereBrady. Two new species of the latter are herein proposed: L. mandubi sp. nov. and L. katu sp. nov. The succession of ostracod assemblages along the studied core changes conspicuously in composition, abundance and preservation, and are characterized by the following associations: Herpetocypris-Cytheridella (lower), Limnocythere-Cypretta (middle) andPotamocypris-Heterocypris (upper). It is assumed that these associations represent different ecological phases of the paleolake Taubaté which is in accordance to previous stratigraphic and paleontological studies in the basin. The results from this pioneering taxonomic and paleoecological study on ostracods from Tremembé Formation reinforce the potential of these fossils for paleolimnological researches in Brazilian Cenozoic deposits. PMID:26221982

  16. Palaeobiogeographical patterns reveal the origins of a pelagic lifestyle in ostracods

    NASA Astrophysics Data System (ADS)

    Perrier, Vincent; Mark, Williams; Siveter David, J.; Robert, Goodall; Elena, Mikhailova; Anna, Tarasenko; Firuza, Salimova

    2016-04-01

    Coupled with evidence from depositional setting, faunal associates and functional morphology, the palaeogeographical distribution patterns of ancient marine organisms can be used as a test of lifestyle. Thus, fossil organisms that are interpreted to have been planktonic throughout their lifecycle (e.g. graptolites), and those with a long-lived planktonic larval stage (e.g. the planula larvae of corals) typically have wide intercontinental distribution, whilst those that have a demersal and short-lived larval stage (e.g. brachiopods), and those that are exclusively benthic (e.g. podocope ostracods) generally have a more restricted biogeographical distribution. Here we develop an independent test of fossil ostracod autoecology using modern distribution patterns to visualize 'geographical domains' for pelagic and benthic lifestyles. These data are statistically filtered in order to match the ranges of geography and bathymetry between Silurian and modern forms. Our analysis decisively identifies Silurian myodocopes with ranges overlapping with modern pelagic ostracods. Though predicated on ostracods, our approach is potentially applicable to analyzing the patterns of any putative arthropod zooplankton in the fossil record where the ecology of modern representatives can be readily determined. Furthermore it may also form a guide to identify fossil zooplanktonic arthropods (like some Ordovician trilobites) that have no modern representatives.

  17. Chester (Mississippian) ostracodes from Bangor Formation of Black Warrior basin, northern Alabama

    SciTech Connect

    Devery, H.; Dewey, C.

    1986-05-01

    A previously unreported ostracode fauna is described from the Bangor Limestone in Franklin, Lawrence, and Colbert Counties, Alabama. The Bangor formation is a Chesterian (Mississippian) platformal carbonate sequence. The predominant carbonates are bioclastic and oolitic grainstones to wackestones with less abundant micritic claystones. Intercalated fine clastics are common in the upper and lower parts of the sequence. This study focuses on the bioclastic limestones with interbedded shales of the lower Bangor. The megafaunal associations include crinoid and blastoid pelmatozoans, orthotetid, and spiriferid brachiopids, and both fenestrate and nonfenestrate bryozoans. Solitary rugose corals and trilobites may be locally abundant. Gastropods and bivalves form a consistent but accessory part of the fauna, which indicates a shallow, nearshore shelf environment. A diverse ostracode fauna of variable abundance has been collected from the shaly units and friable limestones. The ostracode fauna indicates shallow, open-marine conditions and is dominated by bairdiaceans, including Bairdia spp. Rectobairdia and Bairdiacypris. Several species of Cavellina, healdia, and Seminolites are also abundant. Palaeocopids present include Coryellina, Kirkbya, and Polytylites. Kloedenellaceans include Beyrichiopsis, Glyptopleura, Glypotpleurina, and .Hypotetragona. Paraparchitaceans are notably more scarce, but specimens of Shishaella have been found. Some sample have a high valve to carapace ratio, suggesting postmortem transport. Although diversity is high, numerical abundances can be low. Initial studies suggest the ostracodes have a Mid-Continent affinity, which may indicate that the Appalachians were acting as a barrier to migration of European forms.

  18. Systematic paleontology of Quaternary ostracode assemblages from the Gulf of Alaska; Part 3, Family Cytheruridae

    USGS Publications Warehouse

    Brouwers, E.M.

    1994-01-01

    Forty-six species of podocopid ostracodes, most belonging to the Family Cytheruridae, are reported from Quaternary continental-shelf sediments of the Gulf of Alaska. Descriptions and illustrations are provided for 27 new species, 11 previously described species, and 8 species retained in open nomenclature. This report is based on 198 bottom grab samples collected during 1975, 1979, and 1980.

  19. Abyssal ostracods from the South and Equatorial Atlantic Ocean: Biological and paleoceanographic implications

    USGS Publications Warehouse

    Yasuhara, Moriaki; Cronin, T. M.; Martinez, Arbizu P.

    2008-01-01

    We report the distribution of ostracods from ???5000 m depth from the Southeast and Equatorial Atlantic Ocean recovered from the uppermost 10 cm of minimally disturbed sediments taken by multiple-corer during the R/V Meteor DIVA2 expedition M63.2. Five cores yielded the following major deep-sea genera: Krithe, Henryhowella, Poseidonamicus, Legitimocythere, Pseudobosquetina, and Pennyella. All genera are widely distributed in abyssal depths in the world's oceans and common in Cenozoic deep-sea sediments. The total number of ostracod specimens is higher and ostracod shell preservation is better near the sediment-water interface, especially at the 0-1 cm core depths. Core slices from ???5 to 10 cm were barren or yielded a few poorly preserved specimens. The DIVA2 cores show that deep-sea ostracod species inhabit corrosive bottom water near the carbonate compensation depth (CCD) even though their calcareous valves are rarely preserved as fossils in sediment cores due to postmortem dissolution. Their occurrence at great water depths may partially explain the well-known global distributions of major deep-sea taxa in the world's oceans, although further expeditions using minimal-disturbance sampling devices are needed to fill geographic gaps. ?? 2008 Elsevier Ltd. All rights reserved.

  20. Deep-sea ostracode species diversity: Response to late Quaternary climate change

    USGS Publications Warehouse

    Cronin, T. M.; DeMartino, D.M.; Dwyer, G.S.; Rodriguez-Lazaro, J.

    1999-01-01

    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 the Chain 82-24 Core 4PC (41??43'N, 32??51'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) = 0.4 during glacial periods (marine isotope stages 6, 5d, 5b, 4, and 2) to H(S) = 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, S = 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-Cytheropteron characterizing 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.

  1. Ostracode trace metal geochemistry from Lake Tanganyika, Africa: Towards the development of a lacustrine paleothermometer

    NASA Astrophysics Data System (ADS)

    Ash, J.; Cohen, A. S.; Reiners, P. W.; Dettman, D. L.

    2011-12-01

    The development of quantitative lacustrine paleotemperature records is critical to understanding how past climate changes influenced the ecology and hydrology of lakes. Whereas paleoecological transfer functions, TEX-86 and clumped isotopes are all widely applied methods, all have their limitations. We aim to further the development of an alternative method with wider applications: ostracode trace metal geochemistry. Trace element compositions of ostracode valves reflect discriminatory element uptake that in turn reflect ambient environmental conditions and have previously shown promise for quantitative paleotemperature determination. Understanding the specific environmental controls on element concentrations and ratios is an area of active research with much attention focusing on Mg/Ca and Sr/Ca ratios and their relationships with temperature and salinity. Here, HR-ICP-MS geochemical analyses of ostracode valves are compared to an existing TEX-86 temperature record as well as gastropod stable isotopes from Lake Tanganyika, Africa. Two ostracode species (M. opaca and R. ampla) were chosen for analyses from core LT-98-58 (1759 +/- 133 AD-modern). Molar Mg/Ca ratios for M. opaca range from .04 to .16, and a trend towards increased Mg/Ca begins around 1880 AD. Molar Mg/Ca ratios for R. ampla range from .05 to .2, and no trend is discernable. Sr/Ca ratios in both species range from .003-.006 and remain relatively stable, indicating that changes in Mg/Ca are the result of temperature rather than salinity. The M. opaca Mg/Ca record closely resembles the existing TEX-86 paleotemperature record of Tierney et al. (2010) for the past ~240 yr. We intend these preliminary results to facilitate the future research and use of ostracode trace metal geochemistry in a wide range of lakes for paleotemperature reconstruction.

  2. Reconstructing monsoon dynamics on the Tibetan Plateau using ostracod shell chemistry

    NASA Astrophysics Data System (ADS)

    Boerner, N.; De Baere, B.; Yang, Q.; Francois, R. H. G. M.; Jochum, K. P.; Frenzel, P.; Schwalb, A.

    2014-12-01

    Ostracod shells have widely been used as source material for geochemical analysis of stable isotope and trace element composition in paleolimnological reconstruction of lake hydrochemistry and climate as they provide insight into past water balance and solute evolution of lakes. During five fieldtrips to the Tibetan Plateau, taking place between 2008 and 2012, we collected live and sub-recent ostracods from 333 sites. Hydrochemical parameters, such as temperature, electrical conductivity, pH as well as major and minor ion concentrations were measured at each site and show high variability between sites. Adult intact individuals from the most common ostracod taxa were selected and their shell chemistry analyzed. The trace elemental data for the living ostracods compared to the hydrological data provides a calibration dataset for further hydrological and thus climatological reconstruction. Mg/Ca, Sr/Ca and Ba/Ca ratios in ostracod shells provide information about past water temperature and salinity resulting from changes in precipitation vs. evaporation ratios and monsoon activity. Furthermore, Mn/Ca, Fe/Ca and U/Ca ratios are being explored as redox indicators to reconstruct oxygenation cycles. To reconstruct the monsoon dynamics on the Tibetan Plateau, sediment cores from different lakes on an east-west transect were taken: two long sediment cores from lakes Nam Co and Tangra Yumco, covering the past 20,000 years, and a short core from Lake Taro Co. The lakes feature an alkaline environment but show significant differences in their electrical conductivity ranging from 0.99 mS/cm (Taro Co) and 1.8 mS/cm (Nam Co) to 12 mS/cm (Tangra Yumco). The chemical composition of valves of the most common ostracod species in these lakes, Leucocytherella sinensis, was analyzed using laser ablation ICP-MS. The reconstruction provides a more extensive insight in past precipitation - evaporation balance and lake level change and provides clues about the interaction between the

  3. Late Miocene/Pliocene Ostracod Biostratigraphy from South Carpathian Foredeep, Romania (Badislava-Topolog Area)

    NASA Astrophysics Data System (ADS)

    Floroiu, Alina; Stoica, Marius; Vasiliev, Iuliana; Krijgsman, Wout

    2016-04-01

    The Paratethys epicontinental sea has been an essential paleogeographic feature defining the Eurasian interior since Oligocene. By the end of the Miocene, ongoing tectonic activity in the region determined severe restrictions of the connection of the large former Paratethys sea resulting in the formation of several smaller subbasins: the Pannonian basin, the Dacian basin, the Black Sea and the Caspian Sea. In the western part of the Dacian Basin, the thick and continuous Mio-Pliocene sedimentary successions of the Getic Depression of Romania provide an exceptional opportunity to study the paleoecological changes in the Eastern Paratethys during the time when the Mediterranean and Black Sea experienced important sea level changes related to the Messinian Salinity Crisis. These sedimentary successions were the basis of high-resolution magnetobiostratigraphic studies that allow a detailed correlation to the Geological Time Scale. Here, we present the main characteristics of the ostracod assemblages of the Late Miocene/Pliocene sedimentary succession from Badislava-Topolog section covering the Eastern Paratethys regional Maeotian and Pontian, stages that are, at moment, under ongoing formal stratigraphic definition process. The Mio-Pliocene is exposed in the central part of the Getic Depression, especially Topolog-Arges area, where it riches up to 500 m in thickness being incorporated into a large monocline structure with 15o-20o plungeto the south. The Upper Maeotian deposits from the area have developed mainly in fluviatile-deltaic facies with frequent continental intercalations. The ostracod assemblage is represented by rare fresh water ostracods of Candona, Pseudocandona and Ilyocypris genera, capable to populate unstable environments like flood-plains, lakes and rivers with temporary existence. The scarce Maeotian ostracod fauna from this marginal section differs essentially from the more diversified one of the same age recorded in areas that evolved in basinal

  4. The recovery of the ostracod fauna after the Late Devonian mass extinction: the Devils Gate Pass section example (Nevada, USA)

    NASA Astrophysics Data System (ADS)

    Casier, Jean-Georges; Lethiers, Francis

    1998-10-01

    The recovery of the ostracod fauna is rapid after the Late Devonian mass extinction in the Devils Gate Pass section and fifty-nine species have been recognised in the Early Famennian. Forty-five appear for the first time, whereas fourteen others are known from the Late Frasnian (= lazarus species). The ostracod distribution in the Early Famennian at Devils Gate is greatly influenced by regional sedimentological factors principally induced by a drastic sea-level eustatic fall.

  5. Deep-sea ostracode shell chemistry (Mg:Ca ratios) and late Quaternary Arctic Ocean history

    USGS Publications Warehouse

    Cronin, T. M.; Dwyer, G.S.; Baker, P.A.; Rodriguez-Lazaro, J.; Briggs, W.M., Jr.

    1996-01-01

    The magnesium:calcium (Mg:Ca) and strontium:calcium (Sr:Ca) ratios were investigated in shells of the benthic ostracode genus Krithe obtained from 64 core-tops from water depths of 73 to 4411 m in the Arctic Ocean and Nordic seas to determine the potential of ostracode shell chemistry for paleoceanographic study. Shells from the abyssal plain and ridges of the Nansen, Amundsen and Makarov basins and the Norwegian and Greenland seas had a wide scatter of Mg:Ca ratios ranging from 0.007 to 0.012 that may signify post-mortem chemical alteration of the shells from Arctic deep-sea environments below about 1000 m water depth. There is a positive correlation (r2=0.59) between Mg:Ca ratios and bottom-water temperature in Krithe shells from water depths <900 m.

  6. New marine ostracod species from the Middle Eocene of west-central Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Morsi, Abdel-Mohsen M.; Hewaidy, Abdel-Galil A.; Samir, Ahmed

    2016-05-01

    The study of two Eocene sections exposed at Wadi Nukhul and Wadi Tayiba in west-central Sinai, Egypt for ostracods yielded diverse fauna. Investigation of the recorded taxa revealed findings of eight new marine ostracod species, one belonging to the family Krithidae, Parakrithe tayibaensis n. sp., three to the family Cytheruridae, Cytheropteron bicostsatum n. sp., Cytheropteron nukhulensis n. sp. and Cytheropteron speijeri n. sp., three to the family Trachyleberididae: Digmocythere centroreticulata n. sp. in subfamily Brachycytherinae and Buntonia bassiounii n. sp. and Buntonia posteroacuta n. sp. in subfamily Buntoniinae, and one, Xestoleberis posterotruncata n. sp., to the family Xestoleberididae. The newly erected species have been described and compared with nearest known and probably related taxa. Their records in the studied sections are stratigraphically confined to the Middle Eocene (Lutetian-Bartonian) interval.

  7. Evidence for the presence of a heart in Paleozoic ostracodes inconclusive

    USGS Publications Warehouse

    Sohn, I.G.

    1974-01-01

    The presence of a heart in some Paleozoic ostracodes has been inferred by analogy with some living myodocopids that have this organ, and an ordinal classification of the leperditiids has been proposed because of this inference. A review of the present knowledge of the internal shell structure of living myodocopids indicates that there is no basis for interpreting certain markings preserved on fossil molds and steinkerns as indicating the presence of a heart.

  8. Ostracod-based isotope record from Lake Ohrid (Balkan Peninsula) over the last 140 ka

    NASA Astrophysics Data System (ADS)

    Belmecheri, Soumaya; von Grafenstein, Ulrich; Andersen, Nils; Eymard-Bordon, Amandine; Régnier, Damien; Grenier, Christophe; Lézine, Anne-Marie

    2010-12-01

    The stable isotope composition of benthic ostracods from a deep-lake sediment core (JO2004-1) recovered from Lake Ohrid (Albania-Macedonia) was studied to investigate regional responses to climate change at the interface between the north-central European and Mediterranean climate systems. Ostracod valves are present only during interglacial intervals, during the Marine Isotope Stage (MIS) 5 and 1. The ostracod oxygen isotope values (δ 18O) quantitatively reflect changes in the oxygen isotope signal of the lake water (δ 18O L). The interpretation of this record however, is far from straight forward. δ 18O L variations throughout MIS 5/6 transition (TII), MIS 5 and MIS 1 appear to be controlled by site specific hydrological processes as shown by modern isotope hydrology. The δ 18O L trends at TII, MIS 5 and MIS 1 match the timing and the main structural feature of the major regional climate records (Corchia cave δ 18O, Iberian margin Sea Surface Temperature) suggesting that the Ohrid δ 18O L responded to global-scale climate changes, although it seems certain that the lake experienced a significant degree of evaporation and varying moisture availability. The carbon isotope signal (δ 13C) seems to respond more accurately to climate changes in agreement with other JO2004-1 proxies. δ 13C of the ostracod calcite is directly linked to the δ 13C of the dissolved inorganic carbon (DIC) in the lake, which in this case is controlled by the isotopic composition of the DIC in the incoming water and by the internal processes of the lake. High δ 13C during cold periods and low values during warm periods reflect changing vegetation cover and soil activity. These results suggest that Lake Ohrid has the potential to capture a long record of regional environment related-temperature trends during interglacial periods, particularly given the exceptional thickness of the lake sediment covering probably the entire Quaternary.

  9. Marine Ostracod Provinciality in the Late Ordovician of Palaeocontinental Laurentia and Its Environmental and Geographical Expression

    PubMed Central

    Mohibullah, Mohibullah; Williams, Mark; Vandenbroucke, Thijs R. A.; Sabbe, Koen; Zalasiewicz, Jan A.

    2012-01-01

    Background We examine the environmental, climatic and geographical controls on tropical ostracod distribution in the marine Ordovician of North America. Methodology/Principal Findings Analysis of the inter-regional distribution patterns of Ordovician Laurentian ostracods, focussing particularly on the diverse Late Ordovician Sandbian (ca 461 to 456 Ma) faunas, demonstrates strong endemicity at the species-level. Local endemism is very pronounced, ranging from 25% (e.g. Foxe basin) to 75% (e.g. Michigan basin) in each basin, a pattern that is also reflected in other benthic faunas such as brachiopods. Multivariate (ordination) analyses of the ostracod faunas allow demarcation of a Midcontinent Province and a southern Marginal Province in Laurentia. While these are most clearly differentiated at the stratigraphical level of the bicornis graptolite biozone, analyses of the entire dataset suggest that these provinces remain distinct throughout the Sandbian interval. Differences in species composition between the provinces appear to have been controlled by changes in physical parameters (e.g. temperature and salinity) related to water depth and latitude and a possible regional geographic barrier, and these differences persist into the Katian and possibly the Hirnantian. Local environmental parameters, perhaps operating at the microhabitat scale, may have been significant in driving local speciation events from ancestor species in each region. Conclusions/Significance Our work establishes a refined methodology for assessing marine benthic arthropod micro-benthos provinciality for the Early Palaeozoic. PMID:22900000

  10. Modern Distribution of Arctic Ocean Ostracodes: Implications for Applications to Paleoceanographic Reconstructions

    NASA Astrophysics Data System (ADS)

    Brouwers, E. M.; Gemery, L.; Cronin, T. M.; Stepanova, A.; Schornikov, E.

    2009-12-01

    Ostracodes are micro-crustaceans with calcareous bivalved shells whose shell chemistry (Mg/Ca ratios) and species ecology make them useful in paleoceanography. They are particularly common in shallow and deep-water sediments in the Arctic Ocean where they are used to reconstruct bottom water temperature, salinity, sea ice, nutrient productivity, ice-rafting, and other parameters during the last 40 ka. To improve our understanding of ostracodes as Arctic paleoceanographic proxies, we analyzed the distribution of 103 modern species in nearly 600 surface sediment samples, expanding on studies initiated in the 1990s (ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin1995/). This database includes the latitude, longitude, water depth, and bottom water temperatures for each sample and includes materials from the Arctic abyssal plains, major ridges and plateaus, continental shelves of the Kara, Laptev, East Siberian, Chukchi, and Beaufort Seas and several subarctic regions (e.g. Bering Sea, North Atlantic). Our studies show that in the Arctic Ocean, the distribution of ostracode species is controlled by bottom water temperature, salinity, food availability, and sea-ice coverage, which are important information for use in paleoceanographic reconstructions. We will discuss the modern distribution of the following key podocopid genera: Henryhowella, Krithe, Pseudocythere, Acetabulastoma, and Cytheropteron together with the myodocopid genus Polycope.

  11. Post-glacial paleoenvironments of the Lake Winnebago basin, east central Wisconsin, based on ostracodes

    SciTech Connect

    Fielder, R.F.; Smith, G.L.; Fitzgerald, T.M. . Dept. of Geology)

    1994-04-01

    Ostracodes were used to determine post-glacial paleoenvironments of the Lake Winnebago Basin. Following the retreat of the Wisconsinian Green Bay Lobe, Glacial Lake Oshkosh was dammed behind the ice sheet. As the modern Fox River was established, Glacial Lake Oshkosh shrank to form modern Lake Winnebago. Ostracodes were sampled from four vibracores in attempts to correlate sedimentary units and determine paleoenvironments. The oldest unit identified in their vibracores is grayish red clay that is thought to be reworked glacial till that was deposited in a lacustrine setting. This clay is dominated by Candona rawsoni, an ostracod species that prefers cold and deep water. The broken and eroded carapaces of the C. rawsoni in the greyish-red clay suggest reworking and transport, perhaps from the Lake Superior Basin. The contact between the clay and overlying sediments is an erosional unconformity, overlain in some places by gravel. The clay is overlain by coarsening-upward from sandy-silt to medium-grained sand, suggesting a decrease in lake levels and water depths. Raised shorelines 20 and 60 ft above present lake level constitute the geomorphic evidence for higher lake levels. Offshore, at depths of ten to twenty feet, the sediment type above is an olive black organic-rich mud where juveniles of C. rawsoni are the dominant species.

  12. Pliocene-climate history of the western united states derived from lacustrine ostracodes

    USGS Publications Warehouse

    Forester, R.M.

    1991-01-01

    Pliocene sediments from several sites in western North America contain ostracodes indicating deposition in lacustrine and wetland settings. The ostracodes offer a means of reconstructing the aquatic paleoenvironment. Because water temperature, chemistry, and lake volume are coupled to climate, reconstruction of these parameters provides a direct insight into Pliocene climate. The site ages were determined from tephrochronology, paleomagnetics, and associated mammals. The morphology of many ostracode species also provides direct information about the paleoenvironment in which they lived. During the Pliocene (about 3.5-2.5 Ma) some species have unusually ornate carapace morphology indicative of large geologically stable lakes, which must have required a stable climate to sustain them. North American Pliocene climate changed from a modern-like state 4.5-3.5 Ma to a period with greater precipitation and less evaporation than today, 3.5-2.5 Ma. This wetter period, inferred from the large geologically long-lived lakes, implies a stable atmospheric circulation pattern. The stable circulation pattern collapsed around 2.5 Ma and climate returned to a modern-like situation. ?? 1991.

  13. Subcellular preservation in giant ostracod sperm from an early Miocene cave deposit in Australia

    PubMed Central

    Matzke-Karasz, Renate; Neil, John V.; Smith, Robin J.; Symonová, Radka; Mořkovský, Libor; Archer, Michael; Hand, Suzanne J.; Cloetens, Peter; Tafforeau, Paul

    2014-01-01

    Cypridoidean ostracods are one of a number of animal taxa that reproduce with giant sperm, up to 10 000 µm in length, but they are the only group to have aflagellate, filamentous giant sperm. The evolution and function of this highly unusual feature of reproduction with giant sperm are currently unknown. The hypothesis of long-term evolutionary persistence of this kind of reproduction has never been tested. We here report giant sperm discovered by propagation phase contrast X-ray synchrotron micro- and nanotomography, preserved in five Miocene ostracod specimens from Queensland, Australia. The specimens belong to the species Heterocypris collaris Matzke-Karasz et al. 2013 (one male and three females) and Newnhamia mckenziana Matzke-Karasz et al. 2013 (one female). The sperm are not only the oldest petrified gametes on record, but include three-dimensional subcellular preservation. We provide direct evidence that giant sperm have been a feature of this taxon for at least 16 Myr and provide an additional criterion (i.e. longevity) to test hypotheses relating to origin and function of giant sperm in the animal kingdom. We further argue that the highly resistant, most probably chitinous coats of giant ostracod sperm may play a role in delaying decay processes, favouring early mineralization of soft tissue. PMID:24827442

  14. Holocene environmental fluctuations of Lake Bosten (Xinjiang, China) inferred from ostracods and stable isotopes

    NASA Astrophysics Data System (ADS)

    Mischke, S.

    2003-04-01

    Lake Bosten is an oligohaline lake in an intermontane basin of the Tianshan Mountains in northwestern China. The open-basin lake receives water from a large catchment area (56,000 km2) with the Kaidu River as its main tributary. A core of 9.25 m length was drilled at 6.25 m water depth in the southwestern part of the lake near the Kaidu river inflow. Sediments of the core contain authigenic carbonate materials, including calcitic shells of ostracods, charophyte-oogonia and stem incrustations. Five AMS-dating results provided the base to establish the chronology of the core which extends back to about 8.4 cal. ka BP. The majority of the ostracod taxa from the core may be classified into two different groups comprising littoral taxa (Cyclocypris ovum, Cypridopsis vidua, Darwinula stevensoni, Fabaeformiscandona hyalina, Herpetocypris chevreuxi, Heterocypris salina) and taxa reflecting profundal conditions (Candona neglecta, Cytherissa lacustris and Fabaeformiscandona caudata). Among these taxa, C. neglecta and D. stevensoni were the most abundant ostracod species providing more than 50 % of the fossil shells in most core samples. Where C. neglecta peaks D. stevensoni often shows minima abundances and vice versa. Stable isotope data derived from ostracod calcite display large variations throughout the core. d18O and d13C values vary over a range of 10 ‰ and 6.7 ‰ respectively. These large ranges may reflect that Lake Bosten responded like a semi-closed lake at least. Low lake levels inferred from species assemblages correspond to lowest d18O values thus indicating the influence of isotopically light river water at the core site and a low residence time and salinity. High d18O values correspond to higher abundances of Candona neglecta and low abundances of littoral taxa pointing towards deeper conditions, a higher distance of the core site from the river inflow, a higher residence time and corresponding salinity of the lake water. On the base of ostracod and stable

  15. Comparison of oxygen isotope values from bulk lake sediment and ostracod valves

    NASA Astrophysics Data System (ADS)

    Teng, J.; Blisniuk, P.

    2012-12-01

    The oxygen isotope composition of the water in a lake is largely controlled by the isotopic composition of precipitation in the lake's catchment area, which is, in turn, controlled by a variety of geographic and climatic factors. Accordingly, the potential to reconstruct past isotopic compositions of lake water using authigenic minerals formed in isotopic equilibrium with the lake water makes lake sediments a promising target for paleoclimate reconstructions. Several different materials can be utilized to reconstruct the oxygen isotope composition of paleo-lake water. These include biogenic carbonates, such as shells of macrofossils (e.g., clams and snails), microfossils, (e.g., ostracods) and chemically precipitated carbonates in bulk lake sediment. To evaluate the suitability of different materials for the reconstruction of oxygen isotope values of past precipitation, we compared the oxygen isotope values of bulk lake sediments and ostracod microfossils that were extracted from an 800 meters thick sequence of sediments in the Zada Basin, southwestern Tibet. The sediment was wet-sieved for grain size separation, and the <63 um size fraction was used for the analysis of the bulk lake sediment. The ostracod microfossils were typically separated from the 125-500 um size fraction. Ostracod valves were cleaned using deionized water and ultrasound. When this did not successfully clean them, we used a brush under a microscope. Preliminary results of our work yielded oxygen isotope values of -2 to -22 permil for bulk lake sediment and a narrower range of -4 to -15 permil for ostracod valves (relative to PDB). In some stratigraphic levels, the oxygen isotope values differed by as much as 10 permil. These differences are significantly higher than offsets of several permil which are commonly observed as the result of species specific vital effects during biogenic calcite precipitation. A plausible explanation for this is that the lake sediment contains a significant portion

  16. Ostracods (Crustacea) and their palaeoenvironmental implication for the Solimões Formation (Late Miocene; Western Amazonia/Brazil)

    NASA Astrophysics Data System (ADS)

    Gross, Martin; Ramos, Maria Ines; Caporaletti, Marco; Piller, Werner E.

    2013-03-01

    Western Amazonia's landscape and biota were shaped by an enormous wetland during the Miocene epoch. Among the most discussed topics of this ecosystem range the question on the transitory influx of marine waters. Inter alia the occurrence of typically brackish water associated ostracods is repeatedly consulted to infer elevated salinities or even marine ingressions. The taxonomical investigation of ostracod faunas derived from the upper part of the Solimões Formation (Eirunepé; W-Brazil) documents a moderately diverse assemblage (19 species). A wealth of freshwater ostracods (mainly Cytheridella, Penthesilenula) was found co-occurring with taxa (chiefly Cyprideis) usually related to marginal marine settings today. The observed faunal compositions as well as constantly very light δ18O- and δ13C-values obtained by measuring both, the freshwater and brackish water ostracod group, refer to entirely freshwater conditions. These results corroborate with previous sedimentological and palaeontological observations, which proposed a fluvial depositional system for this part of western Amazonia during the Late Miocene. We demonstrate that some endemic, “brackish” water ostracods (i.e., Cyprideis) have been effectively adapted to freshwater conditions. Thus, their occurrence is no univocal evidence for the influence of brackish or marine waters in western Amazonia during the Miocene.

  17. Ostracods (Crustacea) and their palaeoenvironmental implication for the Solimões Formation (Late Miocene; Western Amazonia/Brazil)

    PubMed Central

    Gross, Martin; Ramos, Maria Ines; Caporaletti, Marco; Piller, Werner E.

    2013-01-01

    Western Amazonia's landscape and biota were shaped by an enormous wetland during the Miocene epoch. Among the most discussed topics of this ecosystem range the question on the transitory influx of marine waters. Inter alia the occurrence of typically brackish water associated ostracods is repeatedly consulted to infer elevated salinities or even marine ingressions. The taxonomical investigation of ostracod faunas derived from the upper part of the Solimões Formation (Eirunepé; W-Brazil) documents a moderately diverse assemblage (19 species). A wealth of freshwater ostracods (mainly Cytheridella, Penthesilenula) was found co-occurring with taxa (chiefly Cyprideis) usually related to marginal marine settings today. The observed faunal compositions as well as constantly very light δ18O- and δ13C-values obtained by measuring both, the freshwater and brackish water ostracod group, refer to entirely freshwater conditions. These results corroborate with previous sedimentological and palaeontological observations, which proposed a fluvial depositional system for this part of western Amazonia during the Late Miocene. We demonstrate that some endemic, “brackish” water ostracods (i.e., Cyprideis) have been effectively adapted to freshwater conditions. Thus, their occurrence is no univocal evidence for the influence of brackish or marine waters in western Amazonia during the Miocene. PMID:26523090

  18. Quaternary ostracode and foraminiferal biostratigraphy and paleoceanography in the western Arctic Ocean

    USGS Publications Warehouse

    Cronin, Thomas M.; DeNinno, Lauren H.; Polyak, L.V.; Caverly, Emma K.; Poore, Richard; Brenner, Alec R.; Rodriguez-Lazaro, J.; Marzen, R.E.

    2014-01-01

    The stratigraphic distributions of ostracodes and selected calcareous benthic and planktic foraminiferal species were studied in sediment cores from ~ 700 to 2700 m water depth on the Northwind, Mendeleev, and Lomonosov Ridges in the western Arctic Ocean. Microfaunal records in most cores cover mid- to late Quaternary sediments deposited in the last ~ 600 ka, with one record covering the last ~ 1.5 Ma. Results show a progressive faunal turnover during the mid-Pleistocene transition (MPT, ~ 1.2 to 0.7 Ma) and around the mid-Brunhes event (MBE, ~ 0.4 Ma) reflecting major changes in Arctic Ocean temperature, circulation and sea-ice cover. The observed MPT shift is characterized by the extinction of species that today inhabit the sea-ice free subpolar North Atlantic and/or seasonally sea-ice free Nordic Seas (Echinocythereis sp., Rockalliacf. enigmatica, Krithe cf. aquilonia, Pterygocythereis vannieuwenhuisei). After a very warm interglacial during marine isotope stage (MIS) 11 dominated by the temperate planktic foraminifer Turborotalita egelida, the MBE experienced a shift to polar assemblages characteristic of predominantly perennial Arctic sea-ice cover during the interglacial and interstadial periods of the last 300 ka. These include the planktic foraminifera Neogloboquadrina pachyderma, the sea-ice dwelling ostracodeAcetabulastoma arcticum and associated benthic taxa Pseudocythere caudata,Pedicythere neofluitans, and Polycope spp. Several species can be used as biostratigraphic markers of specific intervals such as ostracodes Rabilimis mirabilis — MIS 5 and P. vannieuwenhuisei extinction after MIS 11, and foraminiferal abundance zones Bulimina aculeata — late MIS 5 and Bolivina arctica — MIS 5-11.

  19. Identification, Discrimination, and Discovery of Species of Marine Planktonic Ostracods Using DNA Barcodes.

    PubMed

    Nigro, Lisa M; Angel, Martin V; Blachowiak-Samolyk, Katarzyna; Hopcroft, Russell R; Bucklin, Ann

    2016-01-01

    The Ostracoda (Crustacea; Class Ostracoda) is a diverse, frequently abundant, and ecologically important component of the marine zooplankton assemblage. There are more than 200 described species of marine planktonic ostracods, many of which (especially conspecific species) can be identified only by microscopic examination and dissection of fragile morphological characters. Given the complexity of species identification and increasing lack of expert taxonomists, DNA barcodes (short DNA sequences for species discrimination and identification) are particularly useful and necessary. Results are reported from analysis of 210 specimens of 78 species of marine planktonic ostracods, including two novel species, and 51 species for which barcodes have not been previously published. Specimens were collected during 2006 to 2008 from the Atlantic, Indian, and Southern Oceans, Greenland Sea and Gulf of Alaska. Samples were collected from surface to 5,000 m using various collection devices. DNA sequence variation was analyzed for a 598 base-pair region of the mitochondrial cytochrome oxidase subunit I (COI) gene. Kimura-2-Parameter (K2P) genetic distances within described species (mean = 0.010 ± 0.017 SD) were significantly smaller than between species (0.260 + 0.080), excluding eight taxa hypothesized to comprise cryptic species due to morphological variation (especially different size forms) and/or collection from different geographic regions. These taxa showed similar K2P distance values within (0.014 + 0.026) and between (0.221 ± 0.068) species. All K2P distances > 0.1 resulted from comparisons between identified or cryptic species, with no overlap between intra- and interspecific genetic distances. A Neighbor Joining tree resolved nearly all described species analyzed, with multiple sequences forming monophyletic clusters with high bootstrap values (typically 99%). Based on taxonomically and geographically extensive sampling and analysis (albeit with small sample sizes

  20. Ecology of the Ostracode Loxoconcha in Chesapeake Bay: Application to Shell Chemistry Calibration

    NASA Astrophysics Data System (ADS)

    Vann, C. D.; Cronin, T. M.; Dwyer, G. S.

    2001-12-01

    The successful application of magnesium/calcium ratios (Mg/Ca) of ostracode shells to paleothermometry depends on understanding both the factors controlling the uptake of Mg into the ostracode calcitic shell and the species' seasonal ecology, which determines the time of year when adult molting occurs. Loxoconcha, a cosmopolitan shallow-water ostracode genus that evolved in the Paleogene, includes more than 500 extant species, many inhabiting temperate regions, making it a potentially valuable tool in Cenozoic paleothermometry. We studied the population ecology of Loxoconcha matagordensis, an epiphytal species common in bays and estuaries along the Atlantic and Gulf Coasts of North America, for application to Holocene paleoclimatology in temperate coastal regions. L. matagordensis populations collected from Zostera marina beds in Chesapeake Bay (N 37° 47'4.3", W 76° 17'44.4"; N 37° 47'4.5", W 76° 17'31.0") show that its population dynamics and Zostera height appear to be regulated primarily by seasonal oscillations in water temperature. As water temperature increased from 14.8° to 24.6° C between April and July 2001, a spring breeding season occurred shifting the age structure of the Loxoconcha population from an entirely adult population (individuals that wintered over) to a predominately juvenile population comprised of all eight growth (molt) stages. Most new adults secreted their shells during May and June, although in some years, a second breeding season may occur in late August/September. Other temperate species of this genus also appear to have spring/early summer adult shell growth. Our results suggest that the Mg/Ca ratios from Holocene adult shells of Loxoconcha obtained from sediment cores provide a record of late spring/early summer water temperature variability linked to decadal and centennial climate processes.

  1. Evasion of predators contributes to the maintenance of male eyes in sexually dimorphic Euphilomedes ostracods (Crustacea).

    PubMed

    Speiser, Daniel I; Lampe, Rebecca I; Lovdahl, Valerie R; Carrillo-Zazueta, Brenna; Rivera, Ajna S; Oakley, Todd H

    2013-07-01

    Sexual dimorphisms have long drawn the attention of evolutionary biologists. However, we still have much to learn about the evolutionary, genetic, and developmental drivers of sexual dimorphisms. Here, we introduce ostracods of the genus Euphilomedes (Myodocopida, Ostracoda, and Crustacea) as a promising new system in which to investigate why and how sexual dimorphisms evolve. First, we ask whether male-skewed selective pressure from pelagic predators may help explain a dramatic sexual dimorphism in which male Euphilomedes have compound eyes, but females do not. Manipulative experiments demonstrate that blindfolding reduces the survival rate of male Euphilomedes when they are exposed to predatory fish. Blindfolding of the female rudimentary eyes (rudiments) does not, however, similarly influence the survival rate of brooding females. Further, numerical estimates of sighting distances, based on reasonable extrapolations from Euphilomedes's eye morphology, suggest that the eyes of male Euphilomedes are useful for detecting objects roughly the size of certain pelagic predators, but not conspecifics. We conclude that eyes do not mediate direct interactions between male and female Euphilomedes, but that differences in predation pressure-perhaps associated with different reproductive behaviors-contribute to maintaining the sexually dimorphic eyes of these ostracods. Second, through transcriptome sequencing, we examined potential gene regulatory networks that could underlie sexual dimorphism in Euphilomedes' eyes. From the transcriptome of juvenile male Euphilomedes' eyes, we identified phototransduction genes and components of eye-related developmental networks that are well characterized in Drosophila and other species. The presence of suites of eye regulatory genes in our Euphilomedes juvenile male transcriptome will allow us, in future studies, to test how ostracods regulate the development of their sexually dimorphic eyes. PMID:23652199

  2. Bathyal ostracodes from the Florida-Hatteras slope, the Straits of Florida, and the Blake Plateau

    USGS Publications Warehouse

    Cronin, T. M.

    1983-01-01

    Epibathyal ostracodes from the Florida-Hatteras slope, the Blake Plateau and the Straits of Florida were studied to determine the relationship of numerous genera and species to bottom-water environmental conditions such as dissolved oxygen and bottom-water temperatures. From a total of 100 samples, 44 samples evenly distributed between 200 and 1100 m water depth and having an average of 325 specimens were examined in detail. Using occurrence data from the adjacent continental shelf, carapace preservation, Rose Bengal staining and population data, indigenous death assemblages were distinguished from transported or reworked fossil specimens. The percent of transported specimens varied as follows: Blake Plateau 90% of the samples and usually constitute 10 to 30% of each. Trachyleberidea, Bairdoppilata, Saida, Paranesidea, Ambocythere, Bythocypris, Cytherella, Bradleya, Henryhowella, and Polycopidae occur in 45 to 80% of the samples in varying percentages. The upper depth limits of 39 taxa occur at or just below the thermocline suggesting a relationship to temperature. Australoecia, Quasibuntonia, Cytheropteron, Ruggieriella, Saida, Ambocythere, Trachyleberidea, Macrocypris, Krithe, "Thalassocythere", and Cytherella are most common or restricted to the O2 minimum zone. Conversely, Anchistrocheles, Bradleya, Henryhowella, and Rockallia are most common below 750 m in well oxygenated water with temperatures below 8??C. The results show that: (1) ostracodes display a narrow depth zonation controlled by dissolved oxygen and water temperature; (2) species diversity is very high for a bathyal zone; (3) ostracodes can be used to identify the source of sediment that has been transported downslope; and (4) some taxa are useful in recognizing low oxygenated water in Cenozoic deposits. ?? 1983.

  3. Coastal Paleoclimate: Unraveling Temperature and Salinity History Using Ostracode Shell Chemistry

    NASA Astrophysics Data System (ADS)

    Dwyer, G. S.; Cronin, T. M.; Vann, C. D.; Kamiya, T.

    2001-12-01

    Long-term records of temperature and salinity of coastal waters are important for understanding coastal environmental change, its linkages to regional, hemispheric or global climate change, and its impact on coastal ecosystems and cultures, yet few reliable, widely applicable temperature and salinity proxies are available for coastal settings. To address this need, we developed magnesium/calcium (Mg/Ca) paleothermometry in calcitic shells of benthic ostracode Loxoconcha, a common genus found in shallow shelf, lagoon, and estuarine systems from tropical to temperate latitudes. Calibration studies, including analysis of field and laboratory-raised specimens as well as ambient water chemistry from a wide range of temperatures and salinties (T=10 to 30 deg. C, S=15 to 40 ppt), confirm a strong Mg/Ca-temperature relationship. We have applied this relation to sediment cores from Chesapeake Bay to reconstruct late Holocene water temperature which, when coupled with benthic ostracode or foraminifer stable oxygen isotopes (\\delta18Ob), permits removal of the temperature effect on \\delta18Ob and the direct calculation of the \\delta18O of the water. This in turn provides an estimate of paleosalinity and regional runoff and precipitation. At salinity below approximately 15 ppt and in regions where coastal geology is dominated by limestone, the Mg/Ca-temperature relation can be complicated due to the influence of runoff on the Mg/Ca ratio of local coastal waters. Such is the case for eastern Florida Bay, where salinity-dependent, runoff-driven changes in water Mg/Ca ratios appear to override the temperature effect on shell Mg/Ca ratios. Multi-decadal to inter-annual variability in ostracode Mg/Ca records from this coastal setting thus primarily reflects salinity fluctuations that appear to be associated with ENSO-driven winter rainfall anomalies.

  4. Identification, Discrimination, and Discovery of Species of Marine Planktonic Ostracods Using DNA Barcodes

    PubMed Central

    2016-01-01

    The Ostracoda (Crustacea; Class Ostracoda) is a diverse, frequently abundant, and ecologically important component of the marine zooplankton assemblage. There are more than 200 described species of marine planktonic ostracods, many of which (especially conspecific species) can be identified only by microscopic examination and dissection of fragile morphological characters. Given the complexity of species identification and increasing lack of expert taxonomists, DNA barcodes (short DNA sequences for species discrimination and identification) are particularly useful and necessary. Results are reported from analysis of 210 specimens of 78 species of marine planktonic ostracods, including two novel species, and 51 species for which barcodes have not been previously published. Specimens were collected during 2006 to 2008 from the Atlantic, Indian, and Southern Oceans, Greenland Sea and Gulf of Alaska. Samples were collected from surface to 5,000 m using various collection devices. DNA sequence variation was analyzed for a 598 base-pair region of the mitochondrial cytochrome oxidase subunit I (COI) gene. Kimura-2-Parameter (K2P) genetic distances within described species (mean = 0.010 ± 0.017 SD) were significantly smaller than between species (0.260 + 0.080), excluding eight taxa hypothesized to comprise cryptic species due to morphological variation (especially different size forms) and/or collection from different geographic regions. These taxa showed similar K2P distance values within (0.014 + 0.026) and between (0.221 ± 0.068) species. All K2P distances > 0.1 resulted from comparisons between identified or cryptic species, with no overlap between intra- and interspecific genetic distances. A Neighbor Joining tree resolved nearly all described species analyzed, with multiple sequences forming monophyletic clusters with high bootstrap values (typically 99%). Based on taxonomically and geographically extensive sampling and analysis (albeit with small sample sizes

  5. Climate change, body size evolution, and Cope's Rule in deep-sea ostracodes.

    PubMed

    Hunt, Gene; Roy, Kaustuv

    2006-01-31

    Causes of macroevolutionary trends in body size, such as Cope's Rule, the tendency of body size to increase over time, remain poorly understood. We used size measurements from Cenozoic populations of the ostracode genus Poseidonamicus, in conjunction with phylogeny and paleotemperature estimates, to show that climatic cooling leads to significant increases in body size, both overall and within individual lineages. The magnitude of size increase due to Cenozoic cooling is consistent with temperature-size relationships in geographically separated modern populations (Bergmann's Rule). Thus population-level phenotypic evolution in response to climate change can be an important determinant of macroevolutionary trends in body size. PMID:16432187

  6. Climatic significance of the ostracode fauna from the Pliocene Kap Kobenhavn Formation, north Greenland

    USGS Publications Warehouse

    Brouwers, E.M.; Jorgensen, N.O.; Cronin, T. M.

    1991-01-01

    The Kap Kobenhavn Formation crops out in Greenland at 80??N latitude and marks the most northerly onshore Pliocene locality known. The sands and silts that comprise the formation were deposited in marginal marine and shallow marine environments. An abundant and diverse vertebrate and invertebrate fauna and plant megafossil flora provide age and paleoclimatic constraints. The age estimated for the Kap Kobenhavn ranges from 2.0 to 3.0 million years old. Winter and summer bottom water paleotemperatures were estimated on the basis of the ostracode assemblages. The marine ostracode fauna in units B1 and B2 indicate a subfrigid to frigid marine climate, with estimated minimum sea bottom temperatures (SBT) of -2??C and estimated maximum SBT of 6-8??C. Sediments assigned to unit B2 at locality 72 contain a higher proportion of warm water genera, and the maximum SBT is estimated at 9-10??C. The marginal marine fauna in the uppermost unit B3 (locality 68) indicates a cold temperate to subfrigid marine climate, with an estimated minimum SBT of -2??C and an estimated maximum SBT ranging as high as 12-14??C. These temperatures indicated that, on the average, the Kap Kobenhavn winters in the late Pliocene were similar to or perhaps 1-2??C warmer than winters today and that summer temperatures were 7-8??C warmer than today. -from Authors

  7. An early to mid-Pleistocene deep Arctic Ocean ostracode fauna with North Atlantic affinities

    USGS Publications Warehouse

    DeNinno, Lauren H.; Cronin, Thomas M.; Rodriquez-Lazaro, J.; Brenner, Alec R.

    2015-01-01

    An early to middle Pleistocene ostracode fauna was discovered in sediment core P1-93-AR-23 (P23, 76.95°N, 155.07°W) from 951 meter water depth from the Northwind Ridge, western Arctic Ocean. Piston core P23 yielded more than 30,000 specimens and a total of about 30 species. Several early to mid-Pleistocene species in the genera Krithe,Echinocythereis, Pterygocythereis, and Arcacythere are now extinct in the Arctic and show taxonomic affinities to North Atlantic Ocean species. Our results suggest that there was a major ostracode faunal turnover during the global climate transitions known as the Mid-Pleistocene Transition (MPT, ~ 1.2 to 0.7 Ma) and the Mid-Brunhes Event (MBE, ~ 400 ka) reflecting the development of perennial sea ice during interglacial periods and large ice shelves during glacial periods over the last 400,000 years.

  8. A 425-million-year-old silurian pentastomid parasitic on ostracods.

    PubMed

    Siveter, David J; Briggs, Derek E G; Siveter, Derek J; Sutton, Mark D

    2015-06-15

    Pentastomids (tongue worms) are worm-like arthropods known today from ∼140 species [1]. All but four are parasitic on vertebrates. Their life cycle typically involves larval development in an intermediate host followed by maturation in the respiratory tract of a definitive terrestrial host. Fossil pentastomids are exceedingly rare and are known only from isolated juveniles [2-6]. The identity of the possible hosts of fossil pentastomids and the origin of their lifestyle have generated much debate. A new, exceptionally preserved species, described based on adults from 425-million-year-old marine rocks, is the only known fossil pentastomid associated with a host, in this case a species of ostracod crustacean. The pentastomids are preserved near eggs within the ostracod and also, uniquely for any fossil or living pentastomid, are attached externally to the host. This discovery affirms the origin of pentastomids as ectoparasitic on marine invertebrates. The terrestrialization of pentastomids may have occurred in parallel with the vertebrate invasion of land. PMID:26004764

  9. Late Quaternary Ostracodes and Paleoceanography from HOTRAX core HLY0503-18, Lomonosov Ridge, Central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gemery, L.; Cronin, T. M.; Darby, D. A.; Jakobsson, M.; Polyak, L. V.

    2009-12-01

    Most Quaternary sediment records from the central Arctic Ocean have low temporal resolution (1-2 cm/kyr), limiting our understanding of millennial-scale climate events such as the Younger Dryas, Preboreal Oscillation and early Holocene thermal maximum. Cores recovered on the 2005 HOTRAX cruise to the central Lomonosov Ridge include intervals with sedimentation rates as high as 10 cm/kyr for the last deglacial interval. Using modern species’ ecology from a modern ostracode database, we analyzed ostracode assemblages from core HLY0503-18TC to reconstruct deglacial and early Holocene bottom water conditions and surface ocean circulation, productivity, and sea-ice conditions. Results show millennial-scale changes in the dominance of indicator ostracode taxa (Polycope, Krithe, Cytheropteron) during the BØlling/AllerØd, Younger Dryas, and early Holocene that we interpret as signifying rapid changes in surface productivity, surface-to-benthic flux of organic material and reduced sea-ice or even ice-free summer conditions. In addition to paleoceanographic implications, ostracode assemblages provide faunal tiepoints that can be used to correlate central Arctic cores, augmenting nannofossil and foraminiferal biostratigraphy and radiocarbon dates complicated by reservoir effects.

  10. Deep-sea ostracods from the South Atlantic sector of the Southern ocean during the Last 370,000 years

    USGS Publications Warehouse

    Yasuhara, Moriaki; Cronin, T. M.; Hunt, G.; Hodell, D.A.

    2009-01-01

    We report changes of deep-sea ostracod fauna during the last 370,000 yr from the Ocean Drilling Program (ODP) Hole 704A in the South Atlantic sector of the Southern Ocean. The results show that faunal changes are coincident with glacial/interglacial-scale deep-water circulation changes, even though our dataset is relatively small and the waters are barren of ostracods until mid-MIS (Marine Isotope Stage) 5. Krithe and Poseidonamicus were dominant during the Holocene interglacial period and the latter part of MIS 5, when this site was under the influence of North Atlantic Deep Water (NADW). Conversely, Henryhowella and Legitimocythere were dominant during glacial periods, when this site was in the path of Circumpolar Deep Water (CPDW). Three new species (Aversovalva brandaoae, Poseidonamicus hisayoae, and Krithe mazziniae) are described herein. This is the first report of Quaternary glacial/interglacial scale deep-sea ostracod faunal changes in the Southern and South Atlantic Oceans, a key region for understanding Quaternary climate and deep-water circulation, although the paucity of Quaternary ostracods in this region necessitates further research. ?? 2009 The Paleontological Society.

  11. A high-elevation MIS 5 hydrologic record using mollusks and ostracodes from Snowmass Village, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Sharpe, Saxon E.; Bright, Jordon

    2014-11-01

    Sediments containing terrestrial and aquatic mollusks and ostracodes from the Ziegler Reservoir fossil site (2705 m elevation) near Snowmass Village, Colorado, span ~ 130-87 ka (MIS 5e through 5b). The southeastern area of the site where taxa were recovered was a relatively fresh, shallow, well-vegetated wetland during MIS 5e through 5c time, approximately 2 m deep, with a total dissolved solids value of ~ 200-1000 mg L- 1. The wetland was seasonally or annually variable and groundwater discharged along the margins of the bounding moraine. Groundwater likely contributed solutes to the system and may have contributed 18O-enriched water. Based on stable isotopes from ostracode calcite (δ18OOST and δ13COST), seasonal evaporation occurred and the dissolved inorganic carbon pool was unexpectedly enriched in 13C. The mollusk and ostracode faunas changed little across the MIS 5e/5d/5c boundaries, whereas a distinct change in the ostracode fauna occurred between the deposition of Unit 11 and Unit 13, which corresponds in time to the MIS 5c/5b boundary, indicating some combination of increased surface and/or groundwater flow, a decrease in water temperature, and a freshening and a possible deepening of the wetland.

  12. Ostracod body size trends do not follow either Bergmann's rule or Cope's rule during periods of constant temperature increase

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Seshadri, P.; Amin, V.; Heim, N. A.; Payne, J.

    2013-12-01

    Over time, organisms have adapted to changing environments by evolving to be larger or smaller. Scientists have described body-size trends using two generalized theories. Bergmann's rule states that body size is inversely related to temperature, and Cope's rule establishes an increase over time. Cope's rule has been hypothesized as a temporal manifestation of Bergmann's rule, as the temperature of the Earth has consistently decreased over time and mean body size has increased. However, during times of constant temperature increase, Bergmann's rule and Cope's rule predict opposite effects on body size. Our goal was to clarify this relationship using both accessible proxies of historic temperature - atmospheric CO2 levels and paleo-latitude. We measured ostracod lengths throughout the Paleozoic and Mesozoic eras (using the Catalogue of Ostracoda) and utilized ostracod latitudinal information from the Paleobiology Database. By closely studying body-size trends during four time periods of constant CO2 increase across spectrums of time and latitude, we were able to compare the effects of Cope's and Bergmann's rule. The correlation, p-values, and slopes of each of our graphs showed that there is no clear relationship between body size and each of these rules in times of temperature increase, both latitudinally and temporally. Therefore, both Cope's and Bergmann's rule act on marine ostracods and no rule is dominant, though our results more strongly disprove the latitudinal variation in ostracod size.

  13. A first calibration of nonmarine ostracod species for the quantitative estimation of Pleistocene climate change in southern Africa

    NASA Astrophysics Data System (ADS)

    Horne, D. J.; Martens, K.

    2009-04-01

    Although qualitative statements have been made about general climatic conditions in southern Africa during the Pleistocene, there are few quantifiable palaeoclimatic data based on field evidence, especially regarding whether the area was wetter or drier during the Last Glacial Maximum. Such information is critical in validating models of climate change, both in spatial and temporal dimensions. As an essential preliminary step towards palaeoclimate reconstructions using fossil ostracods from cored lake sediment sequences, we have calibrated a training set of living ostracod species' distributions against a modern climate dataset and other available environmental data. The modern ostracod dataset is based on the collections in the Royal Belgian Institute of Natural Sciences in Brussels, which constitutes the most diverse and comprehensive collection of southern African nonmarine ostracods available anywhere in the world. To date, c. 150 nominal species have been described from southern Africa (Martens, 2001) out of c. 450 species in the total Afrotropical area (Martens et al., 2008). Here we discuss the potential value and limitations of the training set for the estimation of past climatic parameters including air temperature (July and January means, maxima and minima, Mean Annual Air Temperature), precipitation, water conductivity and pH. The next step will be to apply the Mutual Ostracod Temperature Range method (Horne, 2007; Horne & Mezquita, 2008) to the palaeoclimatic analysis of fossil ostracod assemblages from sequences recording the Last Glacial Maximum in southern Africa. Ultimately this work will contribute to the development of a glacier-climate modelling project based on evidence of former niche glaciation of the Drakensberg Escarpment. Horne, D. J. 2007. A Mutual Temperature Range method for Quaternary palaeoclimatic analysis using European nonmarine Ostracoda. Quaternary Science Reviews, 26, 1398-1415. Horne, D. J. & Mezquita, F. 2008. Palaeoclimatic

  14. Calibrating a new proxy for Pleistocene climate change in southern Africa: the Mutual Ostracod Temperature Range method

    NASA Astrophysics Data System (ADS)

    Horne, David; Martens, Koen

    2010-05-01

    The Mutual Ostracod Temperature Range (MOTR) method has so far been applied only in the European Pleistocene, where it is proving effective in producing past air temperature range estimates that compare well with those obtained by other proxy methods (Horne, 2007; Horne & Mezquita, 2008; Holmes et al., in press). As an essential preliminary step towards applying the method in southern Africa, we have calibrated a training set of living ostracod species' distributions against a modern climate dataset and other available environmental data. The modern ostracod dataset is based on material held by the Royal Belgian Institute of Natural Sciences in Brussels, which constitutes the most diverse and comprehensive collection of southern African nonmarine ostracods available anywhere in the world. To date, c. 150 nominal species have been described from southern Africa (Martens, 2001) out of c. 450 species in the total Afrotropical area (Martens et al., 2008). We used an edited dataset comprising a total of 2,118 records of ostracod species from 748 localities in southern Africa, ranging in latitude from approximately 17 degrees S to 35 degrees S. We have explored the potential value and limitations of this training set for the estimation of past climatic parameters including mean July, January and annual air temperatures, precipitation, water conductivity and pH. Holmes, J. A., Atkinson, T., Darbyshire, D. P. F., Horne, D. J., Joordens, J., Roberts, M. B., Sinka, K. J. & Whittaker, J. E. (accepted, in press). Middle Pleistocene climate and hydrological environment at the Boxgrove hominin site (West Sussex, UK) from ostracod records. Quaternary Science Reviews, doi:10.1016/j.quascirev.2009.02.024, 1-13. Horne, D. J. 2007. A Mutual Temperature Range method for Quaternary palaeoclimatic analysis using European nonmarine Ostracoda. Quaternary Science Reviews, 26, 1398-1415. Horne, D. J. & Mezquita, F. 2008. Palaeoclimatic applications of large databases: developing and testing

  15. A temporary pond in the Early Cretaceous of southern England: palaeoclimatic implications of nonmarine "Purbeck-Wealden" ostracod faunas

    NASA Astrophysics Data System (ADS)

    Horne, D. J.

    2009-04-01

    Excavation of the partial skeleton of an Iguanodon from the Upper Weald Clay (Barremian, Early Cretaceous) at Smokejacks Brickworks near Ockley, Surrey, UK included detailed sampling for micropalaeontological and palynological and studies (Nye et al., 2008). Rich and well-preserved non-marine assemblages of pollen and spores include early angiosperms as well as freshwater green algae. Taphonomic analyses show the ostracod assemblages to be autochthonous thanatocoenoses, indicative of local environment at the time of deposition. Using a palaeobiological approach, the ostracods and palynomorphs demonstrate temporary / ephemeral freshwater conditions at the time when the Iguanodon died and the carcase was buried. Ostracod "faunicycles" in "Purbeck-Wealden" deposits may represent salinity variations in non-marine water-bodies, influenced by the balance between precipitation and evaporation, and/or the relative abundance of permanent and temporary waterbodies in the landscape; many assemblages resulted from post-mortem mixing, perhaps during flood events (Horne, 2002). Faunal alternations may therefore reflect shifts of the boundary between warm temperate and paratropical climate in the Early Cretaceous of NW Europe. The previously rejected suggestion that such assemblage variations record Milankovitch cyclicity deserves to be reconsidered, as does the possibility that they reflect changes on sub-Milankovitch timescales. Climate variability may have influenced the differential evolutionary success of sexual, mixed and parthenogenetic reproductive strategies in nonmarine ostracods. Latitudinally restricted distribution patterns and wind dispersal of resting eggs offer potential for inferring global climate patterns from ostracod palaeobiogeography, although dispersal by large animals (e.g., crocodiles, pterosaurs) is likely to have confused any aeolian transport patterns. References Horne, D. J. 2002. Ostracod biostratigraphy and palaeoecology of the Purbeck Limestone

  16. Late glacial climate estimates for southern Nevada: The ostracode fossil record

    SciTech Connect

    Forester, R.M.; Smith, A.J.

    1995-10-01

    Climate change plays an important role in determining as possible long term hydrological performance of the potential high level nuclear waste repository within Yucca Mountain, Nevada. Present-day global circulation results in this region having an arid to semi-arid climate characterized by hot and relatively dry summers. Global circulation during the late glacial (about 14 to 20 ka) was very different from the present-day. Preliminary study of late-glacial fossil ostracodes from {open_quotes}marsh deposits{close_quotes} in the upper Las Vegas Valley suggests mean annual precipitation may have been four times higher, while mean annual temperature may have been about 10{degrees}C cooler than today. A major difference between present-day and late-glacial climate was likely the existence of cooler, cloudier, and wetter summers in the past.

  17. Episodes of low dissolved oxygen indicated by ostracodes and sediment geochemistry at Crystal Lake, Illinois, USA

    USGS Publications Warehouse

    Curry, B. Brandon; Filippelli, G.M.

    2010-01-01

    Low dissolved oxygen during the summer and early fall controls profundal continental ostracode distribution in Crystal Lake (McHenry County), Illinois, favoring Cypria ophthalmica and Physocypria globula at water depths from 6 to 13 m. These species also thrived in the lake's profundal zone from 14,165 to 9600 calendar year before present (cal yr b.p.) during the late Boiling, Allerod, and Younger Dryas chronozones, and early Holocene. Characterized by sand, cemented tubules, large aquatic gastropod shells, and littoral ostracode valves, thin (1-6 cm) tempestite deposits punctuate thicker deposits of organic gyttja from 16,080 to 11,900 cal yr b.p. The succeeding 2300 yr (11,900-9600 cal yr b.p.) lack tempestites, and reconstructed water depths were at their maximum. Deposition of marl under relatively well-oxygenated conditions occurred during the remainder of the Holocene until the arrival of Europeans, when the lake returned to a pattern of seasonally low dissolved oxygen. Such conditions are also indicated in the lake sediment by the speciation of phosphorus, high concentrations of organic carbon, and abundant iron and manganese occluded to mineral grains. Initial low dissolved oxygen was probably caused by the delivery of dissolved P and Fe in shallow groundwater, the chemistry of which was influenced by Spodosol pedogenesis under a spruce forest. The triggering may have been regionally warm and wet conditions associated with retreat of the Lake Michigan lobe (south-central Laurentide Ice Sheet). ?? 2010, by the American Society of Limnology and Oceanography Inc.

  18. Five Sarsiellidae ostracods (Crustacea: Myodocopida) from the South Coast of Korea (East China Sea).

    PubMed

    Karanovic, Ivana; Soh, Ho-Young

    2015-01-01

    The East China Sea is part of the Warm Temperate Northwest Pacific zoogeographic province and, as such, has a high biodiversity and many tropical and subtropical biotic elements. Nevertheless, many invertebrate groups from this area remain poorly studied. Ostracods are one of them, especially those belonging to the subclass Myodocopa. In this paper we provide the first data on a diverse myodocopid family, Sarsiellidae, not only for the East China Sea, but also for Korea. Five species are reported in this paper from three Korean islands (Jeju, Chuja, and Maemul), and they are only a part of the ostracods collected during this study, indicating a high diversity of the group in this region. Three new species, Eurypylus koreanus sp. nov., Eusarsiella hanguk sp. nov., and Sarsiella nereis sp. nov., clearly stand apart from their respective congeners, mostly by prominent shell characters but also by details of the soft part morphology. Their affinity though clearly indicates a close connection of the region with the more southern zoogeographical realms, especially Central Indo Pacific and partly Temperate Australasia. Two species previously known from Japan (north part of the Sea of Japan and southeastern part of the Pacific Coast of Japan), Sarsiella japonica Hiruta, 1977 and S. misakiensis Kajiyama, 1912, are redescribed. Based on 11 newly obtained COI sequences we construct a preliminary phylogenetic tree, which supports previous hypotheses based on the morphological data, that Eusarsiella Cohen & Kornicker, 1975 is a polyphyletic taxon. With the maps of species distribution provided for each of the three genera, we give an overview of their current zoogeography, and clearly indicate areas that have no data, mostly due to the lack of investigation. PMID:25947749

  19. Atrazine reduces the transmission of an amphibian trematode by altering snail and ostracod host-parasite interactions.

    PubMed

    Gustafson, Kyle D; Belden, Jason B; Bolek, Matthew G

    2016-04-01

    Trematodes are ubiquitous members of aquatic environments, have many functional roles in ecosystems, and can cause diseases in humans, livestock, and wild animals. Despite their importance and reports of parasite population declines, few studies have concurrently assessed the effects of aquatic contaminants on multiple hosts, multiple parasite life cycle stages, and on transmission-related host-parasite interactions. Here, we test the effects of environmentally relevant concentrations of the herbicide atrazine (0, 3, 30 μg/L) on the establishment and development of an amphibian trematode (Halipegus eccentricus) in a first-intermediate snail host (Physa acuta) and in a second-intermediate ostracod host (Cypridopsis sp.). Additionally, we test the interactive effects of atrazine and parasitism on snail and ostracod survival. Our results indicate that atrazine negatively affects trematode transmission by altering snail and ostracod host-parasite interactions. Although atrazine did not affect the survival of uninfected snails alone, atrazine acted synergistically with parasitism to reduce the longevity of infected snails. As a result, the number of cercariae (i.e., larval trematodes) produced by snails was 50.7 % (3 μg/L) and 14.9 % (30 μg/L) relative to controls. Atrazine exhibited direct negative effects on ostracod survival at 30 μg/L. However, when ostracods were also exposed to trematodes, the negative effects of atrazine on survival were diminished. Although infected ostracod survival remained high, trematode development was significantly reduced, resulting in reduced infectivity of metacercariae (i.e., nongravid adult cysts infective to definite host) to 32.2 % (3 μg/L) and 28.6 % (30 μg/L) relative to the controls. The combination of reduced cercaria production and reduced metacercarial infectivity in the 3 and 30 μg/L atrazine treatment groups reduced the net number of infective worms produced to 16.4 and 4.3 % (respectively) relative to the control

  20. Vertical distribution of pelagic ostracods (Myodocopa) in the Subantarctic and Antarctic zones of the Australian-New Zealand sector in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Chavtur, V. G.; Mazdygan, E. R.

    2015-03-01

    Materials from the Russian expeditions in the Australia-New Zealand sector of the Southern Ocean during the period from 1956 until 1983 have been studied. In the Subantarctic zone, the fauna of pelagic ostracods is formed mainly by the allochthonic complex tropical-subtropical and antarctic species. The number of ostracod species, as well as their density and biomass, increase with depth, reaching a maximum at the 400-500-m layer and decreasing closer to the bottom. The vertical distribution of pelagic ostracods is similar in the Antarctic and Subantarctic zones. Nevertheless, the maximum number of species here is determined mainly by the aboriginal complex of widespread and cold-water ostracods, which moves deeper when moving to higher latitudes. There are regular changes in the vertical distribution of dominant species with latitude. They are determined by the specific structure and dynamics of water masses in separate subzones of the study region.

  1. The sediment-contact test using the ostracod Heterocypris incongruens: Effect of fine sediments and determination of toxicity thresholds.

    PubMed

    Casado-Martinez, M Carmen; Burga-Pérez, Karen F; Bebon, Rebecca; Férard, Jean-François; Vermeirssen, Etienne L M; Werner, Inge

    2016-05-01

    The toxicity test using freshwater ostracods of the species Heterocypris incongruens is a sub-chronic static test that exposes individuals to whole sediments over a period of 6 d, the endpoints being mortality and growth. We tested the hypothesis that endpoints of the sediment bioassay using Heterocypris incongruens are affected by the presence of fine sediment particles by testing control sediment supplied with the commercial test kit with increasing proportions of kaolin clay as a proxy for fines. While mortality was not affected, the results showed that increasing the presence of clay reduced ostracod growth. Based on the variability in growth, a sublethal toxicity threshold of 35% is proposed to distinguish effects due to sediment properties from those due to toxicity. The relevance of this threshold was verified using data from toxicity tests of ambient sediment samples with low levels of contamination. PMID:26943743

  2. Magnesium and strontium distributions within valves of a recent marine ostracode, Neonesidea oligodentata: Implications for paleoenvironmental reconstructions

    NASA Astrophysics Data System (ADS)

    Morishita, Tomoaki; Tsurumi, Atsushi; Kamiya, Takahiro

    2007-07-01

    Ostracodes are bivalved microcrustaceans that live in nearly all types of aquatic environments. The chemical compositions of the calcified part of their carapaces are frequently used as an empirical proxy in paleoenvironmental reconstructions. We investigated the compositions and the distribution of Mg and Sr within valves of a recent ostracode, Neonesideaoligodentata, using an electron microprobe analyzer. Each of the investigated valves displayed large variations in Mg and Sr concentrations compared to the variations in Ca (and probably O). There were no systematic chemical differences between right and left valves of each carapace, and between male and female carapaces. Although there were some deviations, the valves consisted of, at least, three chemical bands: (1) a narrow (usually <10 μm) high-Mg, Sr outer band (Outer Band), (2) a heterogeneous low-Mg, Sr middle band (Middle Band), and (3) a high-Mg, low-Sr inner band (Inner Band). The high-Mg, low-Sr Inner Band was well developed at the inner part of the margin, including the marginal infold. The high-Mg, Sr Outer Band is thought to be formed during the early stage of carapace formation when the calcification rate is high, whereas other parts formed at later stages with a relatively slow calcification rates. Since bairdioidean ostracodes, exemplified by Neonesidea oligodentata, have a long geological history and are abundant in many regions, further studies on the mechanism of the Mg/Ca distribution in these ostracodes will provide a suitable tool to estimate paleotemperatures in various marine environments.

  3. Tertiary ostracods of Gebel Withr, southwestern Sinai, Egypt: pal˦ontology, biostratigraphy and pal˦obiogeography

    NASA Astrophysics Data System (ADS)

    Shahin, A.

    2000-08-01

    The exposed Early Eocene-Early Miocene interval in the study area yields considerable amounts of ostracods. A detailed investigation of the ostracod content has led to the recognition of 79 species and subspecies, five of which are reported as new species. They are Semicytherura bassiounii, Semicytherura gammudii, Pterygocythere withrensis, Paracosta reymenti and Cativella bulgi. An attempt to reconstruct a local ostracod biozonation has led to the recognition of six biostratigraphical zones. These biozones are arranged from the youngest to the oldest as follows: Leguminocythereis bopaensis-Leguminocythereis bicostata Assemblage Zone; Reticulina saitoi-Trachyleberis nodosus Assemblage Zone; Asymmetricythere yousefi-Cytherella piacabucuensis Assemblage Zone; Leguminocythereis africana-Buntonia faresi Assenblage Zone; and Grinioneis haidingeri-Pokornyella deformis minor Assemblage Zone. The palaeobathymetric estimates for these assemblages reveals a great deal from the inner neritic to the upper bathyal environments. The cosmopolitan distribution of the recorded species proved to be useful for pal˦obiogeographic reconstruction. This reveals that there was a direct connection throughout the Tethyan realm and a connection between the Tethyan North Africa and West Africa via the Trans-Saharan Seaway, at least until the end of the Palaeocene, through which the migration of benthic organisms had occurred.

  4. Limnocythere bradburyi n.sp.: a modern ostracode from central Mexico and a possible Quaternary paleoclimatic indicator.

    USGS Publications Warehouse

    Forester, R.M.

    1985-01-01

    Limnocythere bradburyi is a new species of nonmarine ostracode that is living in several lakes in the central Mexican Plateau. These lakes are shallow, turbid, and pan-shaped, having relatively unstable and fluid substrates. Water levels of these lakes are high in the summer and low or dry in the winter. These lakes usually contain fresh to slightly saline water during the rainy season (summer-fall) and slightly saline water during the dry season (winter-spring), and have solute composition that is dominated by Na+, HCO3--CO32-, Cl- ions. The regional climate is characterized as humid temperate with mild equitable temperatures throughout the year. Winter temperatures are usually above 0oC, whereas summer temperatures are commonly below 30oC. The water temperature of the lakes containing L. bradburyi generally reflects atmospheric temperatures. The ostracode's life cycle coincides with the climatic wet cycle and is therefore completed during the warmest period of the year, which is in marked contrast to ostracodes living in lakes in the US and Canada that usually begin their life cycle with the spring rain and snow melt in cold water and complete their life cycle in warm water. This contrasting climatic life-cycle pattern between central Mexico and the US may be sufficient to explain why L. bradburyi occurs commonly in many Quaternary deposits in the southwestern US, but has not been found living in the US.-Author

  5. An ostracode based paleolimnologic and paleohydrologic history of Death Valley: 200 to 0 ka

    USGS Publications Warehouse

    Forester, R.M.; Lowenstein, T.K.; Spencer, R.J.

    2005-01-01

    Death Valley, a complex tectonic and hydrologic basin, was cored from its lowest surface elevation to a depth of 186 m. The sediments range from bedded primary halite to black muds. Continental ostracodes found in the black muds indicate that those sediments were deposited in a variety of hydrologic settings ranging from deep, relatively fresh water to shallow saline lakes to spring discharge supported wetlands. The alkaline-enriched, calcium-depleted paleolake waters indicate extrabasinal streamflow and basin-margin spring discharge. The alkaline-depleted, calcium-enriched paleowetland waters indicate intrabasinal spring discharge. During Marine Isotope Stage 6 (MIS 6, ca. 180-140 ka) the hydrologic settings were highly variable, implying that complex relations existed between climate and basin hydrology. Termination II (MIS 6 to MIS 5E) was a complex multicyclic sequence of paleoenvironments, implying that climates oscillated between high and low effective moisture. MIS 4 (ca. 73-61 ka) was a spring discharge supported wetland complex. During MIS 2 (ca. 20-12 ka) the hydrologic settings were variable, although they are not fully understood because some black muds deposited during that time were lost during coring. ?? 2005 Geological Society of America.

  6. Pliocene shallow water paleoceanography of the North Atlantic ocean based on marine ostracodes

    USGS Publications Warehouse

    Cronin, T. M.

    1991-01-01

    Middle Pliocene marine ostracodes from coastal and shelf deposits of North and Central America and Iceland were studied to reconstruct paleotemperatures of shelf waters bordering portions of the Western Boundary Current System (including the Gulf Loop Current, Florida Current, Gulf Stream and North Atlantic Drift). Factor analytic transfer functions provided Pliocene August and February bottom-water temperatures of eight regions from the tropics to the subfrigid. The results indicate: (1) meridional temperature gradients in the western North Atlantic were less steep during the Pliocene than either today or during Late Pleistocene Isotope Stage 5e; (2) tropical and subtropical shelf waters during the Middle Pliocene were as warm as, or slightly cooler than today; (3) slightly cooler water was on the outer shelf off the southeastern and mid-Atlantic coast of the U.S., possibly due to summer upwelling of Gulf Stream water; (4) the shelf north of Cape Hatteras, North Carolina may have been influenced by warm water incursions from the western edge of the Gulf Stream, especially in summer; (5) the northeast branch of the North Atlantic Drift brought warm water to northern Iceland between 4 and 3 Ma; evidence from the Iceland record indicates that cold East Greenland Current water did not affect coastal Iceland between 4 and 3 Ma; (6) Middle Pliocene North Atlantic circulation may have been intensified, transporting more heat from the tropics to the Arctic than it does today. ?? 1991.

  7. Taxonomy of quaternary deep-sea ostracods from the Western North Atlantic ocean

    USGS Publications Warehouse

    Yasuhara, Moriaki; Okahashi, H.; Cronin, T. M.

    2009-01-01

    Late Quaternary sediments from Ocean Drilling Program (ODP) Hole 1055B, Carolina Slope, western North Atlantic (32??47.041??? N, 76??17.179??? W; 1798m water depth) were examined for deep-sea ostracod taxonomy. A total of 13933 specimens were picked from 207 samples and c. 120 species were identified. Among them, 87 species were included and illustrated in this paper. Twenty-eight new species are described. The new species are: Ambocythere sturgio, Argilloecia abba, Argilloecia caju, Argilloecia keigwini, Argilloecia robinwhatleyi, Aversovalva carolinensis, Bythoceratina willemvandenboldi, Bythocythere eugeneschornikovi, Chejudocythere tenuis, Cytheropteron aielloi, Cytheropteron demenocali, Cytheropteron didieae, Cytheropteron richarddinglei, Cytheropteron fugu, Cytheropteron guerneti, Cytheropteron richardbensoni, Eucytherura hazeli, Eucytherura mayressi, Eucytherura namericana, Eucytherura spinicorona, Posacythere hunti, Paracytherois bondi, Pedicythere atroposopetasi, Pedicythere kennettopetasi, Pedicythere klothopetasi, Pedicythere lachesisopetasi, Ruggieriella mcmanusi and Xestoleberis oppoae. Taxonomic revisions of several common species were made to reduce taxonomic uncertainty in the literature. This study provides a robust taxonomic baseline for application to palaeoceanographical reconstruction and biodiversity analyses in the deep and intermediate-depth environments of the North Atlantic Ocean. ?? The Palaeontological Association, 2009.

  8. Hydrochemical effects on the life cycle, shell size, thickness, and chemistry of ostracode Cyprideis torosa

    NASA Astrophysics Data System (ADS)

    Marco-Barba, J.; Ito, E.; Mezquita, F.; Carbonell, E.

    2006-12-01

    Cyprideis torosa is a species of ostracode that inhabits and reproduces in wide range of ionic concentrations as long as (carbonate alkalinity)/Ca ratio is low. It is found in inland springs, lakes, estuaries, wetlands and seawater evaporation ponds as long as its Alk/Ca requirement is met. We collected C. torosa from 20 sites near Valencia, Spain in early spring 2004. Main environmental variables were analyzed in situ or in the lab, including temperature and concentration of major ions and oxygen isotopes. Several (2-20) live individuals were sorted out, their growth instar, sex and size measured and their shell chemistry (Mg/Ca, Sr/Ca and oxygen isotopes) analyzed. Three of these 20 sites were sampled monthly for an entire year, and its population structure, juvenile and adult shell chemistry (between 20 and 40 shells) analyzed. The chemistry of the single-visit sites varied widely with TDS from 9 to 2200 meq/L. Generally, Cl was the most dominant anion, with an averaged value of 76% (16% - 94%). CO3 plus HCO3 varied between 0.4 and 64% and SO4 between 4 and 26%. Principal Components Analysis showed that all waters follow a similar solute evolution trend of increasing Cl and SO4 and decreasing carbonate alkalinity with increasing TDS. Water δ18O also increase with TDS suggesting evaporation is the dominant driver of solute evolution. Among the sites sampled monthly, U1 is a HCO3>Ca>Mg>SO4 spring with the TDS of 9 meq/L. Sites P5 and P7 are part of a coastal wetland system of Cl>Na>Mg~SO4>Ca>HCO3 composition with TDS of 1700meq/L and 270meq/L, respectively. Water temperature varies from 12 to 30°C in P5, 13 to 33°C in P7 and 16 to 30°C in U1. At all 3 sites, the highest temperature occurred in July. The longest animals have the highest shell Ca content, and size is related to water chemistry. Both males and females are smaller in high TDS waters, and in particular, in high SO4 waters. The shell-water oxygen isotope fractionation decreases drastically at higher

  9. Trends in ostracod distribution and water chemistry in subarctic Canada: Churchill (Manitoba) lakes and ponds revisited

    NASA Astrophysics Data System (ADS)

    Viehberg, F. A.; Côté, G.; Pienitz, R.

    2009-04-01

    Ecosystems change in response to factors such as climate variability, invasions, and natural hazards over a short period of time (IPCC 2007). The individual organism has to react to complete its life cycle and eventually to reproduce successfully. Under extreme conditions the survival of the total population depends thoroughly on the genetic diversity/potential and thus the ability to expand its biogeographical range or to run extinct. The knowledge of the specific plasticity in time is essential to interpret signals of biological proxies in palaeo records. We investigated 13 lakes/ponds in the surrounding of the Churchill Northern Studies Centre (CNSC; 58° 43.989'N, 93° 49.219'W), Churchill, Canada in 1997. 9 years later we revisited the same localities in 2006. In addition, faunistic data of microcrustaceans in the local study area is available from the late 80's (Havel et al 1990 a, b). and further instrumental climate records from Churchill (Manitoba, Canada) are daily filed since 1943 by Environment Canada. Thus we were able to pinpoint local warming trends and changes in the water chemistry from our short term records in the subarctic study area. The microcrustacean fauna change consecutively. e.g., freshwater ostracods adopted to short open water periods during the summer, strong variations of water temperatures in the shallow waters and mostly low ionic contents of the host waters are not present in the current record. References: Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990a. Genetics of sexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 65-84. Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990b. Genotypic diversity of asexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 391-410.

  10. Quaternary ostracodes and molluscs from the Rukwa Basin (Tanzania) and their evolutionary and paleobiogeographic implications

    USGS Publications Warehouse

    Cohen, Andrew S.; Van Bocxlaer, Bert; Todd, Jonathan A.; McGlue, Michael; Michel, Ellinor; Nkotagu, Hudson H.; Grove, A.T.; Delvaux, Damien

    2013-01-01

    Much of the spectacular biodiversity of the African Great Lakes is endemic to single lake basins so that the margins of these basins or their lakes coincide with biogeographic boundaries. Longstanding debate surrounds the evolution of these endemic species, the stability of bioprovinces, and the exchange of faunas between them over geologic time as the rift developed. Because these debates are currently unsettled, we are uncertain of how much existing distribution patterns are determined by modern hydrological barriers versus reflecting past history. This study reports on late Quaternary fossils from the Rukwa Basin and integrates geological and paleoecological data to explore faunal exchange between freshwater bioprovinces, in particular with Lake Tanganyika. Lake Rukwa's water level showed large fluctuations over the last 25 ky, and for most of this period the lake contained large habitat diversity, with different species assemblages and taphonomic controls along its northern and southern shores. Comparison of fossil and modern invertebrate assemblages suggests faunal persistence through the Last Glacial Maximum, but with an extirpation event that occurred in the last 5 ky. Some of the molluscs and ostracodes studied here are closely related to taxa (or part of clades) that are currently endemic to Lake Tanganyika, but others testify to wider and perhaps older faunal exchanges between the Rukwa bioprovince and those of Lake Malawi and the Upper Congo (in particular Lake Mweru). The Rukwa Basin has a long history of rifting and lacustrine conditions and, at least temporarily, its ecosystems appear to have functioned as satellites to Lake Tanganyika in which intralacustrine speciation occurred. Paleontological studies of the Rukwa faunas are particularly relevant because of the basin's important role in the late Cenozoic biogeography of tropical Africa, and because many of the molecular traces potentially revealing this history would have been erased in the late

  11. East Asian Summer Monsoon Variations in the Last 1,700 Years Inferred from δ18o of Ostracode Shells

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Sakai, S.; Seto, K.

    2014-12-01

    Oxygen isotope ratios of ostracode shells (δ18Oostracode) from the central part of Lake Nakaumi, southwest Japan were examined to clarify intensity of East Asian summer monsoon (EASM) in the last 1700 years. Adult whole shell of Bicornucythere bisanensis, which grow into adulthood from April to August in the present Nakaumi, was used for δ18O measurements. Long-term trend in δ18Oostracode correspond with salinity changes in Lake Nakaumi caused by regional geographic events based on analysis of fossil ostracode assemblages. Five short-term increases in δ18Oostracode were recognized in 500, 900, 1350, 1650 and 1850 AD, which correspond with weak periods of the EASM intensity based on δ18O of stalagmite in Wanxiang cave. Intensity of EASM is representative of precipitation around the Japan. For recent ostracodes, δ18Oostracode positively correlated with bottom water salinity, which related negatively to precipitation and positively to δ18O of lake water in the recent Nakaumi. Thus, it might be interpreted that the short-term fluctuations in δ18Oostracode were caused by intensity change of EASM, since δ18Oostracode will increase due to low precipitation during weak periods of EASM. Further, the compiled data demonstrate that at least five EASM weakening periods, in 500, 900, 1350, 1650 and 1850 AD, occurred between 30° and 40° N in East Asia in the last 1700 years. These timings accord with data from sites, which suggests that oscillations of the EASM have been synchronous across the region.

  12. Holocene relative sea-level change in Hiroshima Bay, Japan: A semi-quantitative reconstruction based on ostracodes

    USGS Publications Warehouse

    Yasuhara, Moriaki; Seto, Koji

    2006-01-01

    Holocene relative sea-level changes in Hiroshima Bay were reconstructed from fossil ostracodes from a core, using a semi-quantitative method. In Hiroshima Bay, relative sea level rose rapidly (about 25 m) between ca. 9000 cal yr BP and ca. 5800 cal yr BP, after which it gradually fell (about 5 m) to its present level. The peak in relative sea level occurred at ca. 5800 cal yr BP. The sea-level curve for Hiroshima Bay is similar to curves for tectonically stable areas of Japan (e.g., Osaka Bay). ?? by the Palaeontological Society of Japan.

  13. A minute ostracod (Crustacea: Cytheromatidae) from the Miocene Solimões Formation (western Amazonia, Brazil): evidence for marine incursions?

    PubMed Central

    Gross, Martin; Ramos, Maria Ines F.; Piller, Werner E.

    2016-01-01

    A huge wetland (the ‘Pebas system’) covered western Amazonia during the Miocene, hosting a highly diverse and endemic aquatic fauna. One of the most contentious issues concerns the existence, potential pathways and effects of marine incursions on this ecosystem. Palaeontological evidences (body fossils) are rare. The finding of a new, presumably marine ostracod species (Pellucistoma curupira sp. nov.) in the upper middle Miocene Solimões Formation initiated a taxonomic, ecological and biogeographical review of the genus Pellucistoma. We demonstrate that this marine (sublittoral, euhaline), subtropical–tropical taxon is biogeographically confined to the Americas. The biogeographical distribution of Pellucistoma largely depends on geographical, thermal and osmotic barriers (e.g. land bridges, deep and/or cold waters, sea currents, salinity). We assume an Oligocene/early Miocene, Caribbean origin for Pellucistoma and outline the dispersal of hitherto known species up to the Holocene. Pellucistoma curupira sp. nov. is dwarfed in comparison to all other species of this genus and extremely thin-shelled. This is probably related to poorly oxygenated waters and, in particular, to strongly reduced salinity. The associated ostracod fauna (dominated by the eurypotent Cyprideis and a few, also stunted ostracods of possibly marine ancestry) supports this claim. Geochemical analyses (δ18O, δ13C) on co-occurring ostracod valves (Cyprideis spp.) yielded very light values, indicative of a freshwater setting. These observations point to a successful adaptation of P. curupira sp. nov. to freshwater conditions and therefore do not signify the presence of marine water. Pellucistoma curupira sp. nov. shows closest affinities to Caribbean species. We hypothesize that Pellucistoma reached northern South America (Llanos Basin) during marine incursions in the early Miocene. While larger animals of marine origin (e.g. fishes, dolphins, manatees) migrated actively into the Pebas

  14. Live/Dead Comparisons of Ostracodes in Temperate Lakes Reveal Evidence of Human Impact and Provides a Tool to Measure the Progress of Remediation Efforts

    NASA Astrophysics Data System (ADS)

    Spergel, J.; Kimball, K. C.; Fitzpatrick, S. A.; Michelson, A. V.; Leonard-Pingel, J.

    2015-12-01

    Lake ecosystems face a multitude of environmental threats including: eutrophication, overfishing, and heavy metal pollution. Tools to identify lakes impacted by human activity and quantify that impact are needed to combat their environmental degradation. One such promising tool has been the comparison between living communities and associated time-averaged death assemblages of mollusks in marine environments. Here we extend the reach of such live/dead comparisons using ostracodes in temperate lakes. We sampled six lakes in Wisconsin for living communities and associated death assemblages of ostracodes: two lakes impacted by human activity, two relatively "pristine" lakes, and two remediated lakes. We took sixteen grab samples of the upper centimeter of sediment in each lake, capturing simultaneously living benthic ostracodes and discarded valves of dead ostracodes. We found that impacted lakes had lower live/dead fidelity in taxonomic composition and rank-order abundance distributions and greater within-lake variation in death assemblages than "pristine" lakes. Additionally, the living communities in the impacted lakes tended to be lower in species richness and have lower evenness than "pristine" lakes. Remediated lakes displayed similar live/dead fidelity in taxonomic composition and rank-abundance distributions to "pristine" lakes and had lower within-lake variation in death assemblages than impacted lakes. Remediated lakes also contained living communities that tended to be richer and more even than impacted lakes. The lower live/dead fidelity of ostracodes in impacted lakes indicate live/dead ostracode comparisons can provide a tool to identify lake ecosystems impacted by humans. The similar results of remediated and "pristine" lakes indicate remediation efforts in these lakes have been successful in alleviating environmental impact detrimental to ostracode communities. This result indicates live/dead comparisons of ostracodes can be a useful tool to monitor

  15. 5,000 years of water level changes infered from ostracod assemblages in a lowland lake in Romania (Central Eastern Europe)

    NASA Astrophysics Data System (ADS)

    Iepure, Sanda; Hutchinson, Simon; Namiotko, Tadeusz; Feurdean, Angelica

    2014-05-01

    Oscillations of lake levels in Central Eastern Europe during the Holocene are crucial records of past regional climatic conditions reflecting the balance between evaporation and precipitation in their catchment. Lake Stiucii (38 ha, 10 m depth) is located in Transylvanian Plain (NW Romania) at 296 m asl. A recently extracted sediment core from the central part of the lake provides the first ostracod sediment record of the lake water level fluctuations in this region covering the last 5000 cal years BP. The sediment sequence yielded approximately 1600 valves of 18 freshwater and halophile ostracod species of 11 genera. The most abundant and frequent in the entire record were Heterocypris salina (Brady 1868), Limnocythere inopinata (Baird 1843) and Plesiocypridopsis newtoni (Brady & Robertson 1870) (abundance range between 16-25%). The ostracod assemblages also show a marked variability in diversity and abundance over the past 5000 years, which appear to closely follow water level oscillations. The assemblages indicate three periods of low diversity and density of ostracods primarily represented by Candonidae between (i) 3800 and 3150 cal yr BP, (ii) 2900 and 2400 cal yr BP and (iii) 1600 and 1200 cal yr BP and probably reflect a response to low lake water levels. This inference is supported by the deposition of gyttja and low Zr concentrations. The dominance of Cyclocypris ovum (Jurine, 1820) and Candoninae in a ostracod community of otherwise poor density and diversity between 2200 and 1800 cal yr BP probably reflects littoral environments in the central, deepest part of the present lake. The ostracod assemblages diversified (up to 10 species) between 1100 and 250 cal yr BP and are dominated by co-occurrences of halophile species e.g. Heterocypris salina and Plesiocypridopsis newtoni until 700 cal yr BP, suggesting increased supply of salty water into the lake by salt springs. Thereafter Limnocythere inopinata, a typical shallow water species (<10 m) is dominant

  16. Exceptionally preserved lacustrine ostracods from the Middle Miocene of Antarctica: implications for high-latitude palaeoenvironment at 77° south

    PubMed Central

    Williams, Mark; Siveter, David J; Ashworth, Allan C; Wilby, Philip R; Horne, David J; Lewis, Adam R; Marchant, David R

    2008-01-01

    A newly discovered Konservat-Lagerstätte from the Middle Miocene of the western Olympus Range, Dry Valleys, Antarctica, yields cypridoidean ostracods complete with preserved body and appendages. This is the first record of three-dimensionally fossilized animal soft tissues from the continent. The ostracods are preserved in goethite, secondary after pyrite, representing a novel mode of exceptional preservation. They signal a high-latitude (greater than 77° south) lake setting (Palaeolake Boreas) viable for benthic animal colonization prior to 14 Myr ago. Their presence supports the notion of warmer, tundra-like environmental conditions persisting in the Dry Valleys until the Middle Miocene. PMID:18647723

  17. Pliocene (3.2-2.4 Ma) ostracode faunal cycles and deep ocean circulation, North Atlantic Ocean

    USGS Publications Warehouse

    Cronin, T. M.; Raymo, M.E.; Kyle, K.P.

    1996-01-01

    Ostracode assemblages from Deep Sea Drilling Project Sites 607 (western Mid-Atlantic Ridge) and 610 (southeast Rockall Plateau) show rapid, systematic shifts during late Pliocene glacial-interglacial cycles that reflect deep-sea environmental change. Progressive decreases in North Atlantic deep-water taxa and increases in Southern Ocean taxa occur from 3.4 to 2.4 Ma, and high-amplitude faunal cycles begin near 2.8 Ma. Four ostracode assemblages, each with a characteristic phase relative to 41 k.y. obliquity glacial-interglacial ??18O cycles, characterize the benthic faunal record at Site 607. Cross-spectral analysis shows that the Site 607 glacial assemblage has a 41 k.y. periodicity significant at the 95% level; other assemblages show a less significant, but still obvious, concentration of variance at 41 k.y. Faunal patterns suggest climatically controlled reorganization of deep-sea benthic communities during glacial-interglacial cycles due to oscillating deep-sea environments.

  18. Stable isotope values (δ18O & δ13C) of multiple ostracode species in a large Neotropical lake as indicators of past changes in hydrology

    NASA Astrophysics Data System (ADS)

    Pérez, Liseth; Curtis, Jason; Brenner, Mark; Hodell, David; Escobar, Jaime; Lozano, Socorro; Schwalb, Antje

    2013-04-01

    Modern lake hydrodynamics, ostracode species autecology, stable isotopes (δ18O and δ13C) of multiple ostracode species, ostracode taphonomy and sediment geochemistry were studied to improve interpretation of the late Pleistocene-early Holocene (˜24-10 ka) stable isotope record of ostracodes in sediment core PI-6 from Lago Petén Itzá, northern Guatemala. Oxygen and carbon stable isotopes in modern and fossil species assemblages of Lago Petén Itzá were used as indicators of changes in the balance between evaporation and precipitation, past lake level and carbon source. Ostracode taphonomy was used to detect past periods of strong currents, high-energy environments, and possible partial or full mixing of the lake. The modern lake water isotopic composition displays clear seasonal differences that are independent of lake level fluctuations. Modern benthic species displayed lower δ18O and δ13C values than nektobenthic species, with differences of 3.0‰ and 5.3‰, respectively. Valves of nektobenthic species display higher values of δ13C because these ostracodes live in shallower environments among abundant algae and aquatic plants, where productivity is high. The benthic species Limnocythere opesta Brehm, 1939 displayed the smallest average offset from δ18O water (+0.3‰) and the largest offset from δ13CDIC values (-4.1‰) among studied ostracode species. Nektobenthic species Heterocypris punctata Keyser, 1975 displayed the smallest difference relative to the δ13CDIC values (-0.1‰). Late Pleistocene-early Holocene climate conditions and water levels in Lago Petén Itzá can be summarized as follows: 1) high lake levels and cold conditions (Last Glacial Maximum [LGM], ˜24-19 ka), 2) fluctuating lake levels and cold conditions (Heinrich Stadial 1 [HS1], ˜19-15 ka), 3) high lake levels and warm and wetter conditions (Bølling-Allerød [BA], ˜15-13 ka), 4) low lake levels and dry conditions (Younger Dryas [YD], ˜13-11.5 ka) and 5) high lake levels and

  19. Unusual carbon and oxygen isotropic ratios of ostracodal calcite from last interglacial (Sangamon episode) lacustrine sediment in Raymond Basin, Illinois, USA

    USGS Publications Warehouse

    Curry, B. Brandon; Anderson, T.F.; Lohmann, K.C.

    1997-01-01

    The stable isotopic records of ostracode valves deposited during the last interglaciation in Raymond Basin, Illinois, have ??13C and ??18O values as high as +16.5??? and +9.2??? respectively, the highest values yet reported from continental ostracodal calcite. Located in south-central Illinois, Raymond, Pittsburgh, Bald Knob, and Hopwood Farm basins collectively have yielded important long pollen and ostracode records that date from about 130 000 years ago to the present. Although fossils from the present-day interglaciation are not well preserved, these records constitute the only described, conformable, fossiliferous successions of this age from the interior of glaciated North America. The high ??13C values from Raymond Basin are attributed to the residual effects of methane loss either by ebullition or by emission through the stems of senescent emergent aquatic vegetation. A mass balance model suggests that an increase in ??13C of dissolved inorganic carbon on the order of +15??? is possible within a few hours given modest rates of methanogenesis of about 0.02 mol m-2 d-1. The ??13C records from other studies of ostracode valves have values approaching, but not exceeding about +14??? suggesting a limiting value to ???13C enrichment due to simultaneous inputs and outputs of dissolved inorganic carbon. Values of ??18O in ostracodal calcite are quite variable (-4 to +9???) in sediment from the late Sangamon subepisode. A model of isotopic enrichment in a desiccating water body implies that a reduction in reservoir volume of 20% could produce this range of isotopic values. High humidity and evaporation probably account for most of the ??18O variability.

  20. Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

    USGS Publications Warehouse

    Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

    2010-01-01

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

  1. Combined in-situ Trace Element, Pb, Sr Isotope Analysis and U-Th Dating of Speleothems and Ostracods

    NASA Astrophysics Data System (ADS)

    Jochum, K. P.; Scholz, D.; Mertz-Kraus, R.; Gleixner, G.; Guenther, F.; Schwalb, A.; Kuzmin, D.; Stoll, B.; Weis, U.; Izmer, A. V.; Andreae, M. O.

    2010-12-01

    Terrestrial and marine calcium carbonate deposits, such as speleothems and corals, can be used as high-resolution paleoclimate archives. A promising new application is the investigation of ostracod shells. We have developed a LA-ICP-MS technique for combined in-situ trace element, isotope (208Pb/206Pb, 207Pb/206Pb, 87Sr/86Sr) and 230Th-232Th-234U-238U analysis in carbonates. High spatial resolution is obtained by using small spot sizes of 12 - 100 µm. The technique has been applied to a stalagmite from Hüttenbläserschachthöhle, western Germany, and ostracod shells found in lake sediments from Lake Nam Co, Tibet. We focused on a 4 mm long section of the stalagmite that grew continuously for 400 years at 106,000 years B.P. The section includes a transition from aragonite to calcite. Spatial resolution of the trace element analyses is 12 µm corresponding to a temporal resolution of about 1 year. The speleothem calcite is characterized by high Mg (~ 2,000 µg g-1), low Sr (~ 30 µg g-1), Ba (~ 4 µg g-1) and U (~0.04 µg g-1), whereas aragonite has low Mg (~10 µg g-1), high Sr (~ 700 µg g-1), Ba (~ 50 µg g-1) and U (~ 8 µg g-1). Thorium and REE abundances are very low in the ng g-1 range. Calcitic sections probably reflect periods of high recharge, whereas aragonitic sections correspond to dry climate. Remarkable in this context is the steady increase of U, Ba, Sr, Y, Pb, Cd and 208Pb/206Pb in aragonite towards the transition. This may reflect progressively more humid conditions, finally leading to precipitation of calcite. In the U-rich section of the stalagmite, in-situ U-Th-dating by LA-ICP-MS was performed, however, with significantly larger uncertainties of the activity ratios (ca. 3 %) compared to high-precision MC-ICP-MS data (ca. 0.2 %). We also analyzed very small (ca. 0.5 - 1 mm) and thin (about 0.05 mm) ostracod shells from eight levels of a Holocene lake sediment core. 34 major and trace element concentrations could be determined by EPMA and LA

  2. A 4500-year ostracod record from Lake Shkodra (Albania): palaeoenvironmental and palaeoclimatic reconstruction using a multi proxy approach.

    NASA Astrophysics Data System (ADS)

    Mazzini, Ilaria; Gliozzi, Elsa; Koci, Rexhep; Zanchetta, Giovanni; Baneschi, Ilaria; Sadori, Laura; Giardini, Marco; Van Welden, Aurelien; Bushati, Salvatore

    2013-04-01

    During September 2003 several cores were retrieved from the Albanian side of Lake Shkodra. Among them, a 7,8 m long composite core (SK13) has been selected for multidisciplinary analysis: ostracods, characeae, pollen, CaCO3 content and stable isotopes. The chronological framework of SK13 was established through the recognition of four well-dated tephra layers and four 14C accelerator mass spectrometry measurements; the sedimentation rate has been calculated as an average of 0.2 cm a -1(Sulpizio et al 2010, Van Welden et al. 2008). Ostracods have been recovered from 337 samples of 2cm3 in volume, collected almost continuously along the cores. Each sample corresponds to ca. 10 years. Ostracods are abundant and well preserved in all samples, represented by adults and juveniles. On the whole, 13 species have been recovered with different frequencies. Among them, some are endemic of the lake (Candona montenigrina, and Limnocythere scutariense), others are known from other Balcanic lakes and are recorded for the first time in Shkodra (Paralimnocythere georgevitschi in Lake Ohrid, Candona paionica and Candona "angulata" meridionalis in Lake Dorjan). The remaining taxa (Darwinula stevensoni, Pseudocandona marchica, Cypria ophtalmica, Ilyocypris gibba, Cypridopsis vidua, and Metacypris cordata, Cyclocypris sp. and Zonocypris sp.) are widely distributed in central and southern Europe, but signalled for the first time in Albania. The faunal composition is quite homogeneous, with the percentages of the different species varying along the sediment core. The main change occurs at about 1200 cal a BP, where 8 ostracod species disappear and the frequency of the remaining 5 species dramatically increases. This major change reflects the CaCO3 trend with its major peak around 1200 cal a BP. On the contrary, the Characeae display an opposite behaviour, occurring continuously from the base of the core until about 1200 cal a BP, when they as well disappear. The δ18Oc record shows

  3. Biotic Response of Deep-Ocean Ostracodes to the Paleocene-Eocene Thermal Maximum: An Assessment of Past, Present, and Future studies

    NASA Astrophysics Data System (ADS)

    Schellenberg, S. A.; Landau, E. A.

    2007-12-01

    Ostracodes are the only commonly preserved deep-ocean metazoans and provide an important perspective on benthic conditions through the global carbon cycle perturbation known as the Paleocene-Eocene Thermal Maximum (PETM). The classic global Cenozoic study of >250 micron size-fraction ostracode faunas from 1,000+ samples drawn from 150+ DSDP sites by Benson et al. (1984) revealed marked transient declines in abundance, richness, and Shannon diversity in the late Paleocene, but these data are discretized within relatively coarse one-Myr averaged bins and may have little direct temporal or causal relationship with the much shorter PETM. Following the "discovery" of the PETM by Kennett and Stott in the early 1990s, Steineck and Thomas (1994) examined the >150 micron size-fraction ostracode faunas through the PETM at upper bathyal Site 689B on Maud Rise, and argued for a marked relative increase in small, thin walled "opportunistic" taxa capitalizing upon transient conditions of increased food, decreased dissolved oxygen, and decreased carbonate saturation. However, our subsequent cm-scale bulk carbonate carbon-isotope chemostratigraphy for Site 689 confirms that only two of these faunal samples are located within the carbon-isotope excursion of the PETM. Recent high-resolution geochemical analyses of ODP PETM sections in the Southern Ocean are producing a new benchmark for integrative approaches to understanding the PETM. Cast within these environmental frameworks, our recent >63 micron size-fraction ostracode faunal analyses at Maud Rise (690B) and Kerguelen Plateau (738C) reveal marked declines in ostracode accumulation rates and resampled (abundance- corrected) generic richness coincident with the CIE onset and varying rates of recovery following the CIE minimum. Cluster and ordination analyses support major faunal perturbations through the CIE and subsequent recovery towards pre-CIE faunal composition and structure following the CIE. The relatively rapid recovery

  4. A new interstitial ostracod species of the genus Paracobanocythere from Vietnam, with mitochondrial CO1 sequence data of three Asian species

    PubMed Central

    Tanaka, Hayato; Dung, Le Doan; Higashi, Ryouichi; Tsukagoshi, Akira

    2016-01-01

    Abstract This study is a first report of an interstitial ostracod from Southeast Asia. The ostracod species, Paracobanocythere vietnamensis sp. n., was found in the marine interstitial environment of Phu Quoc Island, Vietnam. Thus far, three species of this genus have been described. The morphology of the carapace as well as the appendages of this new species are quite similar to Paracobanocythere hawaiiensis and Paracobanocythere watanabei. However, we found that they could be easily distinguished according to the morphology of the male copulatory organ. Additionally, we estimated the evolutionary distances among these three species based on nucleotide and amino acid sequences of the mitochondrial CO1 gene. Similar morphologies of carapaces and appendages, and relatively small evolutionary distances according to CO1 between Paracobanocythere vietnamensis sp. n. and Paracobanocythere watanabei suggest that these two species are very closely related. PMID:27006603

  5. A new interstitial ostracod species of the genus Paracobanocythere from Vietnam, with mitochondrial CO1 sequence data of three Asian species.

    PubMed

    Tanaka, Hayato; Dung, Le Doan; Higashi, Ryouichi; Tsukagoshi, Akira

    2016-01-01

    This study is a first report of an interstitial ostracod from Southeast Asia. The ostracod species, Paracobanocythere vietnamensis sp. n., was found in the marine interstitial environment of Phu Quoc Island, Vietnam. Thus far, three species of this genus have been described. The morphology of the carapace as well as the appendages of this new species are quite similar to Paracobanocythere hawaiiensis and Paracobanocythere watanabei. However, we found that they could be easily distinguished according to the morphology of the male copulatory organ. Additionally, we estimated the evolutionary distances among these three species based on nucleotide and amino acid sequences of the mitochondrial CO1 gene. Similar morphologies of carapaces and appendages, and relatively small evolutionary distances according to CO1 between Paracobanocythere vietnamensis sp. n. and Paracobanocythere watanabei suggest that these two species are very closely related. PMID:27006603

  6. Climate variability during the Medieval Climate Anomaly and Little Ice Age based on ostracod faunas and shell geochemistry from Biscayne Bay, Florida: Chapter 14

    USGS Publications Warehouse

    Cronin, Thomas M.; Wingard, Georgiana L.; Dwyer, Gary S.; Swart, Peter K.; Willard, Debra A.; Albietz, Jessica

    2012-01-01

    An 800-year-long environmental history of Biscayne Bay, Florida, is reconstructed from ostracod faunal and shell geochemical (oxygen, carbon isotopes, Mg/Ca ratios) studies of sediment cores from three mudbanks in the central and southern parts of the bay. Using calibrations derived from analyses of modern Biscayne and Florida Bay ostracods, palaeosalinity oscillations associated with changes in precipitation were identified. These oscillations reflect multidecadal- and centennial-scale climate variability associated with the Atlantic Multidecadal Oscillation during the late Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Evidence suggests wetter regional climate during the MCA and drier conditions during the LIA. In addition, twentieth century anthropogenic modifications to Everglades hydrology influenced bay circulation and/or processes controlling carbon isotopic composition.

  7. Givetian ostracods of the Candás Formation (Asturias, North-western Spain): taxonomy, stratigraphy, palaeoecology, relationship to global events and palaeogeographical implications.

    PubMed

    Maillet, Sebastien; Milhau, Bruno; Vreulx, Michel; Posada, Luis-Carlos Sánchez De

    2016-01-01

    Asturian ostracods of the Givetian carbonate Candás Formation are documented for the first time from the Peran-Perlora and Carranques reference sections. More than 1,200 specimens were extracted from 44 samples by means of the hot acetolysis method. In all, 75 taxa are described herein, of which 21 are formally described and one, Evlanella peranensis Maillet n. sp., is new. All the taxa are marine benthic and belong to the Eifelian Mega-Assemblage. The assemblages recognized are representative of semi-restricted to shallow open-marine palaeoenvironments above the storm wave base. The stratigraphical distribution of the taxa shows a strong faunal renewal in the top of the Candás Formation. Long-ranging taxa found at the base of the formation, of which many are known from the base of the Middle Devonian, disappear within the base of the member C and are replaced above, around the Middle/Upper Givetian boundary, by more cosmopolitan taxa characteristic of the Frasnian. The lower half of the member C is also characterized both by unstable environments and occurrence of some short-ranging opportunistic ostracod taxa. This renewal within shallow water ostracod communities is probably a consequence of the global Taghanic Biocrisis, leading world-widely to extinctions in several faunal groups. Faunal affinities with Givetian ostracod taxa reported in other areas of the world reflect the commonly accepted palaeogeographical patterns. Close relations between the Cantabrian Zone (NW-Spain), the Armorican Massif (W-France), the Mouthoumet Massif (S-France) and North Africa (Morocco and Algeria) suggest a narrow oceanic space between the western European terranes and the northern Gondwanan margin that involves an advanced phase of closure of the Medio-European Ocean. PMID:27395904

  8. Systematic paleontology of Quaternary ostracode assemblages from the Gulf of Alaska, Part 1: Families Cytherellidae, Bairdiidae, Cytheridae, Leptocytheridae, Limnocytheridae, Eucytheridae, Krithidae, Cushmanideidae

    SciTech Connect

    Brouwers, E.M.

    1990-01-01

    Thirty-two species of podocopid ostracodes are reported from Quaternary sediments of the Gulf of Alaska continental shelf. Fifteen new species are described (Neonesidea sitkagi, Cytheromorpha eskerensis, C. grandwashensis, C. molniai, Munseyella melzeri, M. ristveti, Pectocythere janae, P. kiklukhensis, P. marincovichi, P. tsiuensis, Cluthia foresteri, Krithe burkholderi, K. adelspergi, Pontocythere dahlgrenensis, P. jefferiesensis), twelve previously described species are illustrated, and five species are placed in open nomenclature.

  9. Impact of relative sea level and extreme climate events on the Southern Skhira coastline (Gulf of Gabes, Tunisia) during Holocene times: Ostracodes and foraminifera associations' response

    NASA Astrophysics Data System (ADS)

    Zaïbi, Chahira; Kamoun, Fekri; Viehberg, Finn; Carbonel, Pierre; Jedoui, Younes; Abida, Habib; Fontugny, Michel

    2016-06-01

    This study examines the evolution of the Skhira coast (Southeastern Tunisia) during Holocene times, by analyzing ostracodes, foraminifera and mollusk associations in subsurface sediments of both sebkhas of Dreîaa and El Guettiate. Nine biofacies represented by (1) five categories of lagoon namely widely opened, opened, brackish estuarine, closed and emerged; (2) the maximum of closure of environment revealed by continental and sebkha biofacies; (3) a peculiar two biofacies, formed by coarse sands or shelly clays and dominated by mollusk fragments and showing a mixture of lagoonal, marine and brackish taxa of mollusk, ostracods and foraminifera which provide evidence of high energy events (storms). The lower Holocene continental sediments are overlain by two transgressive categories of biofacies. The first one corresponds to a widely opened lagoon biofacies, related to the first Holocene marine transgression, around 7.46 ka cal BP. The second one, more important, consists of an opened lagoon biofacies between 6.67 and 5.91 ka cal BP. Sudden changes, during Holocene time, in the numerical distribution of foraminifera and ostracods species up cores are used to infer the change from widely opened lagoon, subjected to estuarine influences, to sebkha by passing by a close lagoonal environment. The enrichment of the sediment in quartz grains coupled with the action of the current drift authorized the build-up of sandy spits in front of the estuaries and the genesis of lagoon that preserve a rich assemblage of euryhaline foraminifera, ostracods and mollusks species. This process was interrupted by two distinct high-energy events. The break of sand spits induced the introduction of washover clay deposits at 5.418 ka cal BP and washover coarse sands at 644 a cal BP rich in mixture of brackish and marine macrofauna and microfauna.

  10. A checklist of Recent non-marine ostracods (Crustacea: Ostracoda) from Thailand, including descriptions of two new species.

    PubMed

    Savatenalinton, Sukonthip; Suttajit, Maitree

    2016-01-01

    A checklist covering a total of 67 Recent non-marine ostracod species from Thailand, belonging to 33 genera and seven families (Cyprididae, Candonidae, Ilyocyprididae, Notodromadidae, Darwinulidae, Limnocytheridae, Loxoconchidae), is presented. Twenty-five of these are considered endemic to the Oriental region, 17 of which are Thai endemics. Two        species (Hemicypris exiqua Broodbakker, 1983, and Notodromas sinensis Neal & Zhao, 1991) are new records for the Oriental region, and four species (Cypretta seurati Gauthier, 1929, Chrissia ceylonica (Daday, 1898), Chrissia formosa (Klie, 1938), and Dolerocypris fasciata (O.F. Müller, 1776)) are new record for Thailand. The most diverse subfamily in Thailand is the Cypricercinae, with 22 species. The most diverse genera are Strandesia Stuhlmann, 1888 (eight species), followed by Pseudostrandesia Savatenalinton & Martens, 2009 (seven species) and Stenocypris Sars, 1889 (five species). Other enigmatic groups and new taxa occur in the checklist, but these need to be described elsewhere in the future. For example, several species of Cypridopsinae Kaufmann, 1900, Cyclocypridinae Kaufmann, 1900, Candoninae Kaufmann, 1900 and other groups await description. Considering regional distributions based on frequency of occurrences, rare      species constitute a large fraction, whereas very common species are minor elements. Most of the records were reported from the Northern and Northeastern parts of Thailand. Sampled habitat types ranged from ponds, (oxbow) lakes, swamps, reservoirs, springs, canals, rivers, rice fields, waterfalls, and damp leaf litter. Most of the Thai ostracod fauna exists in a wide range of habitats. A brief discussion on the distribution of described species is included with the list.       Additionally, in the present contribution, we describe two new species, Dolerocypris sisaketensis n. sp. and           Hungarocypris suranareeae n. sp., from the Northeastern part of

  11. Leperditicopid ostracodes from Ordovician rocks of Kentucky and nearby states and characteristic features of the order Leperditicopida

    USGS Publications Warehouse

    Berdan, J.M.

    1984-01-01

    Leperditicopid ostracodes from the Ordovician formations of Kentucky occur in micritic to fine-grained carbonate rocks believed to represent shallow-water facies. They are found at widely separated horizons in the Middle Ordovician High Bridge Group, the Middle and Upper Ordovician Lexington Limestone, and the Upper Ordovician Ashlock, Bull Fork, and Drakes Formations. In this sequence, the leperditicopes are represented by two genera of leperditiids, Eoleperditia Swartz, 1949 and Bivia Berdan, 1976, and six isochilinid genera, Isochilina Jones, 1858, Teichochilina Swartz, 1949, Ceratoleperditia Harris, 1960, Parabriartina n. gen., Kenodontochilina n. gen., and Saffordellina Bassler and Kellett, 1934; the type species of the hitherto poorly known genus Saffordellina, S. muralis (Ulrich and Bassler, 1923), is redescribed and refigured. In all, 18 taxa, of which 2 are in open nomenclature, are described and illustrated. In addition, the family Isochilinidae Swartz, 1949 is redefined to include genera without marginal brims and with straight ventral contact margins. The morphological characteristics of leperditicopid genera are discussed, and a table listing described genera and their diagnostic features is included.

  12. The role of watercourse versus overland dispersal and niche effects on ostracod distribution in Mediterranean streams (eastern Iberian Peninsula)

    NASA Astrophysics Data System (ADS)

    Castillo-Escrivà, Andreu; Rueda, Juan; Zamora, Laia; Hernández, Ramón; Moral, Mónica del; Mesquita-Joanes, Francesc

    2016-05-01

    The processes behind the heterogeneous distribution of species involve a combination of environmental and spatial effects. In the spatial context, stream networks constitute appropriate systems to compare the relative importance of two dispersal modes in aquatic organisms: overland and watercourse dispersal. In the present study, we analyzed the distribution of ostracod species in a river network in the eastern Iberian Peninsula, with variation partitioning between environmental and spatial factors, using Moran and Asymmetric Eigenvector Maps (MEMs, AEMs) as spatial variables. Our aims were to determine the relative importance of environmental and spatial control and to compare the importance of overland and watercourse dispersal for species distribution of passively-dispersing aquatic organisms. Our results suggest that watercourse was the most important dispersal mode, favoring mass-effects. The role of species sorting was significant and related to temperature, stream width and water quality, measured as a biotic index (IBMWP). These results stress the major importance of connectivity, besides niche-related factors, in structuring riverine communities of passively-dispersing aquatic organisms.

  13. Sedimentology, conodonts and ostracods of the Devonian - Carboniferous strata of the Anseremme railway bridge section, Dinant Basin, Belgium

    USGS Publications Warehouse

    Casier, J.-G.; Mamet, B.; Preat, A.; Sandberg, C.A.

    2004-01-01

    as Late praesulcata Zone, with the Early and Middle praesulcata Zones unrepresented because of an hiatus or unconformity. Sparse conodont faunas suggest that only the two next-to-oldest Carboniferous duplicata and sandbergi Zones are represented in the higher part of the Hastie??re Formation. The oldest Carboniferous sulcata Zone and possibly part ofthe duplicata Zone are unrepresented because of an hiatus or unconformity above bed 159. Ostracods are abundant and diversified at most levels in the Anseremme railway bridge section and sixty taxa, the majority in open nomenclature, have been identified and nearly all of them are figured. The ostracod fauna is indicative of shallow-marine environments between fair-weather and storm wave bases in the Etroeungt Formation, and to shallower water conditions periodically subjected to minor salinity variations in the base of the Hastie??re Formation. The upper part of the Hastie??re Formation is marked by a sea-level rise associated with a moderate decrease of the oxygenation of bottom waters. The intra-Devonian hiatus at the Etroeungt-Hastie??re boundary shows no abnormal extinctions and no appearance of new taxa. Thus, the Hangenberg Event is not recognizable in the studied section. Neither the sedimentological analysis nor the palaeontological study of the Bocahut quarry in the Avesnois and of the Anseremme railway bridge section confirm the hypothesis of a highstand for the Hastie??re Formation.

  14. Orbital and suborbital variability in North Atlantic bottom water temperature obtained from deep-sea ostracod Mg/Ca ratios

    USGS Publications Warehouse

    Cronin, T. M.; Dwyer, G.S.; Baker, P.A.; Rodriguez-Lazaro, J.; DeMartino, D.M.

    2000-01-01

    Magnesium/calcium (Mg/Ca) ratios were measured in the deep-sea ostracod (Crustacea) genus Krithe from Chain core 82-24-4PC from the western mid-Atlantic Ridge (3427 m) in order to estimate ocean circulation and bottom water temperature (BWT) variability over the past 200,000 years. Mg/Ca ratios have been used as a paleothermometer because the ratios are controlled primarily by ambient water temperatures at the time the organism secretes its adult carapace. Over the past two glacial-interglacial cycles, Mg/Ca values oscillated between about 7 mmol/mol and 12 mmol/mol, equivalent to a BWT range of 0 to > 3.5??C. The lowest values were obtained on specimens from glacial marine isotope stages (MISs) 2, 4 and 6; the highest values were obtained from specimens from the early part of the Holocene interglacial (MIS 1), and also from MISs 5 and 7. These trends suggest that BWTs in the North Atlantic Ocean fluctuate over orbital time scales. Suborbital variability in Mg/Ca ratios and BWT was also observed for the past 100,000 years. Ratios rose from ~8 mmol/mol to ~10 mmol/mol (implying a BWT increase of ~1 to 3??C) during 14 Mg/Ca excursions. The highest ratios were found in Krithe dated at approximately 32, 36-38, 43, 48, 73, 85 and 93 ka. Although the age model for the Chain 82-24-4PC and temporal resolution do not allow precise correlation, some of these deep-sea bottom temperature excursions appear to correspond to Heinrich events recorded in other regions of the North Atlantic and perhaps Dansgaard-Oeschger interstadial events recorded in Greenland ice cores. If confirmed, this would support the hypothesis that millennial-scale oscillations of climate in the North Atlantic are capable of affecting global climate via thermohaline circulation changes. (C) 2000 Elsevier Science B.V.

  15. Mid-Pliocene deep-sea bottom-water temperatures based on ostracode Mg/Ca ratios

    USGS Publications Warehouse

    Cronin, T. M.; Dowsett, H.J.; Dwyer, G.S.; Baker, P.A.; Chandler, M.A.

    2005-01-01

    We studied magnesium:calcium (Mg/Ca) ratios in shells of the deep-sea ostracode genus Krithe from a short interval in the middle Pliocene between 3.29 and 2.97 Ma using deep-sea drilling sites in the North and South Atlantic in order to estimate bottom water temperatures (BWT) during a period of climatic warmth. Results from DSDP and ODP Sites 552A, 610A, 607, 658A, 659A, 661A and 704 for the period Ma reveal both depth and latitudinal gradients of mean Mg/Ca values. Shallower sites (552A, 610A and 607) have higher mean Mg/Ca ratios (10.3, 9.7, 10.1 mmol/mol) than deeper sites (661A, 6.3 mmol/mol), and high latitude North Atlantic sites (552A, 610A, 607) have higher Mg/Ca ratios than low latitude (658A: 9.8 mmol/mol, 659A: 7.7 mmol/mol, 661A: 6.3 mmol/mol) and Southern Ocean (704: 8.0 mmol/mol) sites. Converting Mg/Ca ratios into estimated temperatures using the calibration of Dwyer et al. (1995) [Dwyer, G.S., Cronin, T.M., Baker, P.A., Raymo, M.E., Buzas, J.S., Corre??ge, T., 1995. North Atlantic deepwater temperature change during late Pliocene and late Quaternary climatic cycles. Science 270, 1347-1351] suggests that mean middle Pliocene bottom water temperatures at the study sites in the deep Atlantic were about the same as modern temperatures. However, brief pulses of elevated BWT occurred several times between 3.29 and 2.97 Ma in both the North and South Atlantic Ocean suggesting short-term changes in deep ocean circulation.

  16. How a low tissue O2 strategy could be conserved in early crustaceans: the example of the podocopid ostracods.

    PubMed

    Corbari, Laure; Carbonel, Pierre; Massabuau, Jean-Charles

    2004-12-01

    An adaptation strategy whereby O(2) partial pressure, P(O(2)), in the tissues is maintained within a low, narrow range of 1-3 kPa, largely independent of the inspired P(O(2)), has been reported in water- and air-breathing poikilotherms and in homeotherms. Based on the postulate that this basic cellular mechanism has been established since the early stages of evolution, it has been hypothesized that it could be the consequence of an early adaptation strategy to maintain cellular oxygenation within the same low and primitive range. To test this hypothesis we studied the basic mechanisms of oxygen regulation in podocopid ostracods, minute crustaceans that have existed on earth for at least 500 million years. Podocopids lack any regulatory mechanism for adapting their ventilation to cope with changes in water oxygenation, and instead adjust their tissue oxygenation status by migrating through the O(2) gradient to sediment layers where the P(O(2)) of the water is 3-5 kPa. Experimental manipulation of the O(2) profile induced their vertical migration to follow this precise water P(O(2)) and demonstrates the existence of a regulation strategy. This strategy must be associated with the lower P(O(2)) values within the animal's carapace valves, showing that podocopids can actively regulate their tissue P(O(2)) at constant but even lower values than the water. In conclusion, the low tissue P(O(2)) strategy could have existed in early crustaceans and, by extension, in early animals. PMID:15557027

  17. Effects of nano-sized zero-valent iron (nZVI) on DDT degradation in soil and its toxicity to collembola and ostracods.

    PubMed

    El-Temsah, Yehia S; Joner, Erik J

    2013-06-01

    Nano-sized zero valent iron (nZVI) has been studied for in situ remediation of contaminated soil and ground water. However, little is known about its effects on organisms in soil and aquatic ecosystems. In this study, the effect of nZVI on degradation of DDT and its ecotoxicological effects on collembola (Folsomia candida) and ostracods (Heterocypris incongruens) were investigated. Two soils were used in suspension incubation experiments lasting for 7 and 30 d; a spiked (20 mg DDT kg(-1)) sandy soil and an aged (>50 years) DDT-polluted soil (24 mg DDT kg(-1)). These were incubated with 1 or 10 g nZVI kg(-1), and residual toxicity in soil and the aqueous phase tested using ecotoxicological tests with collembola or ostracods. Generally, addition of either concentration of nZVI to soil led to about 50% degradation of DDT in spiked soil at the end of 7 and 30 d incubation, while the degradation of DDT was less in aged DDT-polluted soil (24%). Severe negative effects of nZVI were observed on both test organisms after 7 d incubation, but prolonged incubation led to oxidation of nZVI which reduced its toxic effects on the tested organisms. On the other hand, DDT had significant negative effects on collembolan reproduction and ostracod development. We conclude that 1 g nZVI kg(-1) was efficient for significant DDT degradation in spiked soil, while a higher concentration was necessary for treating aged pollutants in soil. The adverse effects of nZVI on tested organisms seem temporary and reduced after oxidation. PMID:23522781

  18. Molluscan and ostracod successions from Dierden's Pit, Swanscombe: insights into the fluvial history, sea-level record and human occupation of the Hoxnian Thames

    NASA Astrophysics Data System (ADS)

    White, Tom S.; Preece, Richard C.; Whittaker, John E.

    2013-06-01

    Swanscombe, Kent, is an internationally renowned hominin site located on the south bank of the River Thames, east of London. The Swanscombe sequence has been reconstructed from exposures at several localities from which important archaeological and palaeontological assemblages have been recovered. The most important of these is Barnfield Pit, where two stone-tool industries (Clactonian and Acheulian) have been recorded in superposition, together with three refitting pieces of a hominin skull associated with the Acheulian. Dierden's Pit (=Ingress Vale), ˜0.5 km to the north of Barnfield Pit, has also yielded Palaeolithic artefacts but is best known as a source of abundant non-marine molluscs and as the type locality for the water vole Arvicola cantiana. This paper describes the molluscan and ostracod successions through the Dierden's Pit sequence, which shed light on important aspects of the fluvial, sea-level and archaeological histories of the Thames during MIS 11. A dramatic change occurs in the molluscan record at Swanscombe, marked by the appearance of the ‘Rhenish suite’ of freshwater molluscs, which has previously been used to suggest confluence of the Thames and Rhine systems. The ‘Rhenish suite’ occurs in the Middle Gravels at Barnfield Pit and throughout the Shell bed at Dierden's Pit, where the component species did not appear simultaneously but colonized the Thames in an ordered sequence. The occurrence of the ‘Rhenish suite’ provides a secure basis for correlation of important archaeological horizons at Swanscombe, which have previously been mis-correlated on the basis of artefact typology. Moreover, it enables correlation with other MIS 11 sequences, some of which (Clacton and East Hyde) can be directly linked to the pollen stratigraphy of the Hoxnian. The ostracod succession at Dierden's Pit provides the first clear evidence of increasing brackish influence at Swanscombe and has formed the basis for palaeoclimatic reconstructions using

  19. A systematic revision of the ostracode species described by Ulrich and Bassler and by Malkin from the Chesapeake Group in Maryland and Virginia

    USGS Publications Warehouse

    Forester, Richard M.

    1980-01-01

    Those ostracode species described by Ulrich and Bassler (1904) and Malkin (1953) from the Chesapeake Group of early Miocene to early Pleistocene age are treated systematically. Lectotypes are designated for all species which have syntypic suites and the lectotypes, holotypes, or hypotypes for all but two species are illustrated. A new genus Otikocythere is proposed, with Cythere punctistriata Ulrich and Bassler 1904 as the type species. A new species, Hulingsina calvertensis, is also proposed. All of the species are placed in an updated biostratigraphic framework.

  20. Ostracods and sediment geochemistry as indicators of hydrologic and climatic variability in the central part of the Mexican Chihuahuan Desert over the last 27 ka cal BP

    NASA Astrophysics Data System (ADS)

    Chávez Lara, C. M.; Roy, P. D.; Lozano Santa Cruz, R.; López Balbiaux, N.

    2013-12-01

    The paleolake Santiaguillo (Durango State) is located in the central part of the Chihuahuan Desert (Mexico). The lacustrine basin covers an area of approximately 1,964 km2 and is surrounded by mountains up to ca. 2,700 masl. This basin was formed by tectonic processes and the basement is formed by volcanic felsic rocks of Tertiary age. Four sediment cores were obtained from central and western part of the basin to reconstruct hydrologic and climate variability during the late Pleistocene and Holocene. In this work, we present paleo-ecology of ostracods and sedimentary geochemistry from two sediment cores (300 cm and 200 cm long) collected from the western basin margin. The age model was constructed from 8 AMS radiocarbon dates and the longest profile represents the last 27 cal ka BP. The ostracode faunal content consists of 4 different species: Limnocythere bradburyi, Cadona patzcuaro, Cypridopsis vidua and Limnocythere ceriotuberosa (listed from highest to lowest abundance) and total abundance varies between 0 and 125 valves/g. Paleo-environmental conditions were reconstructed from the Total Organic Carbon (TOC), Total Inorganic Carbon (TIC), Carbon/Nitrogen ratios (C/N), Chemical Index of Alteration (CIA) and concentrations of Ti, Ca, Si and Al. The results were divided into two zones for interpretation. Zone 1 covers ca. 27-17 cal ka BP (300-191 cm) and is characterized by higher Ti concentrations and above average CIA values. This suggests greater interaction between water and sediment, lower evaporation and relatively higher lake level in the basin. During this interval of higher lakestand, the deposited organic matter was autochthonous (lacustrine origin) and ostracodes suggest presence of a warm and dilute water column (>13 °C and >100 ppm). Sediments of the last 17 cal ka BP (191-0 cm) (Zone 2) are characterized by below average water-sediment interaction, higher carbonate precipitation and deposition of allochthonous organic matter (terrestrial origin

  1. Exceptionally well-preserved giant spermatozoa in male and female specimens of an ostracod Cypria ophtalmica (Crustacea: Ostracoda) from Late Glacial lacustrine sediments of Southern Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Iepure, Sanda; Namiotko, Tadeusz; Valdecasas, Antonio G.; Magyari, Enikö K.

    2012-07-01

    Exceptionally well-preserved giant spermatozoa observed between abundant decalcified carapace valves of ostracods (Crustacea: Ostracoda) were found in Late Glacial to Holocene (14,400 to 10,000 cal years bp) lacustrine sediments in the southern Romanian Carpathians. Analysis by scanning electron microscopy and laser scanning confocal microscopy revealed good preservation of the appendages enabling specific identification as Cypria ophtalmica (Candonidae) and indication of the presence of both female and male specimens based on the sexual dimorphism of the second antenna. This record represents the oldest and richest direct evidence of virtually morphologically unaltered animal spermatozoa preserved in females after mating.

  2. Taxonomy and bathymetric distribution of the outer neritic/upper bathyal ostracodes (Crustacea: Ostracoda) from the southernmost Brazilian continental margin.

    PubMed

    Bergue, Cristianini Trescastro; Coimbra, João Carlos; Ramos, Maria Inês Feijó

    2016-01-01

    Sixty-five ostracode species belonging to 41 genera and 17 families were recorded in the outer shelf and upper slope off Rio Grande do Sul and Santa Catarina states, southernmost Brazil, between 100 and 586 m water depth interval. The ostracode occurrences are hypothesized to be influenced by both, the coastal waters and the Antarctic Intermediate Water (AAIW). The taxonomy of some species of Bradleya Hornibrook, 1952, Legitimocythere Coles & Whatley, 1989 and Henryhowella Puri, 1957 previously described in the same study area is revised. Bradleya gaucha sp. nov., Legitimocythere megapotamica sp. nov., Apatihowella acelos sp. nov., Apatihowella capitulum sp. nov., Apatihowella besnardi sp. nov., Apatihowella convexa sp. nov., and Aversovalva tomcronini sp. nov. are herein proposed. Trachyleberis aorata Bergue & Coimbra, 2008 is reassigned to the genus Legitimocythere and Bradleya pseudonormani Ramos et al., 2009 has its diagnosis emended. Bythocypris praerenis Brandão, 2008 is considered a junior synonym of Bythocypris kyamos Whatley et al., 1998a. Apatihowella Jellinek & Swanson, 2003 and Legitimocythere species have well-defined bathymetric distributions and are potential paleoceanographic markers for the Quaternary in the Southern Brazilian Margin. PMID:27395992

  3. Assessment of impact of geochemical and environmental properties on the meiofauna (benthic foraminifer, ostracod, mollusc) assemblages: A case study in The Late Quaternary Sediments In The Gulf Of Izmir (Eastern Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Yümün, Zeki Ü.

    2016-04-01

    The drilling samples collected from varying depths at 1.00-13.00 m at four different localities of Karsiyaka, Bayrakli, Inciralti and Urla (Çesmealti) in the Gulf of Izmir were studied for their geochemical, sedimantological and micropaleontological properties. The purpose of this study is to describe the meiofauna of the sediments, to determine the pollution history of the gulf and to show the effect of the pollution on the foraminifera and ostracoda. Examination of the loose sediments reveals that the gulf has been affected by the sea for a long time, and it had a rich microfaunal assemblages. Both foraminiferal tests and ostracod carapaces have coloring, and morphological abnormalities have been determined in foraminiferal tests. Peneroplis pertusus (Forskal) and P. planatus (Fichtel and Moll) have blue and black colored tests, while morphological abnormalities were observed on the tests of Ammonia compacta Hofker, Elphidium complanatum (d'Orbigny), E. crispum (Linné), E. macellum (Fichtel and Moll). The ostracod carapaces are generally gray-black colored. Heavy metal (Cr, Mn, Zn, Co, Ni, Cu) analyses have been carried out on the sediments of the Gulf of Izmir. Heavy metal concentrations are high in Bayrakli, and low in Urla (Çesmealti). Cr, Mn and Zn values are the highest in Bayrakli, whereas Co, Ni and Cu values are the highest in Inciralti. Scanning Electron Microscope (SEM) analyses were performed and no heavy metal was detected on the white and colored ostracod carapaces. When the white and colored ostracod carapaces are compared, the coloured ostracode carapace has higher Mg content, and also includes Fe, Al, N, Cl and K. Based on the results obtained, it is observed that the Bayrakli region have been more affected by the pollution than Urla (Çesmealti).

  4. Limnocytherid Ostracod Paleoecology and Stable Isotope Chemistry: Evidence of Climate Change Derived From Lough Monreagh Sediment, Western Ireland

    NASA Astrophysics Data System (ADS)

    Mc Kenzie, S. M.; Patterson, W. P.; Holmden, C.; Tibert, N. E.

    2008-12-01

    higher δ18O values in the Candonids represent a transition from bedrock dominated DIC of the lake water to terrestrial vegetation dominated DIC associated with increasing temperature and humidity. Further warming and increased humidity are inferred by the sudden appearance of very high concentrations of the littoral, warm water (14-20°C), eutrophic Limnocytherid Metacypris cordata at 8.7Kyr that exhibit low δ13C (-6 to -9‰VPDB) and high δ18O values (-2 to -4‰VPDB) that persist to the base of the peat at 7.8Kyr, when the lake becomes a blanket bog that limits ostracod shell preservation. The 8.2Kyr cold event appears at 8.425Kyr, evidenced by a 4‰ increase in δ13C and a sharp reduction in total ostracoda population from ~40 to 10 specimens per sample. Lough Monreagh isotope data from Limnocytherid fossil carapaces display a 12‰ shift in δ13C values over the last ~12,000 years indicative of a major shift in DIC control from bedrock weathering to vegetation adjacent to the lake. Oxygen isotope data infer changes in moisture source from meltwater-influenced surface waters during the Late Glacial and Younger Dryas periods and normal marine water during other periods.

  5. Mg/Ca, Sr/Ca, δ18O and δ13C chemistry of Quaternary lacustrine ostracode shells from the North American continental interior

    NASA Astrophysics Data System (ADS)

    Ito, Emi

    The application of fossil ostracode shell chemistry to the reconstruction of past continental climate must take into consideration both short-term and long-term changes in the hydrologic budget of the lakes. This is particularly true when working in areas of strong seasonality in temperature and precipitation and negative effective moisture where many lakes owe their existence to inflow from groundwater. Moreover the chemistry (especially Mg/Ca and Sr/Ca) and δ18O of lake water may respond differently to hydrologic changes depending on whether they are caused by climate or other factors. These complications make clear how important it is to have information on ostracode ecology, to conduct a time-series monitoring study of the modern system, and to employ other proxy records. Examples of such studies are available from many semi-arid and arid regions of the world. Here I use Rice and Coldwater Lakes, North Dakota, as examples from the northern Great Plains of North America to illustrate these points. Decadally resolved Mg/Ca ratio variations for Rice Lake for the last 2000 years show excellent correlation with the GISP2 ice core δ18O record sampled at the same temporal resolution. Mg/Ca data for Rice and Coldwater Lakes also show good agreement with each other and with diatom-inferred salinity records for Coldwater as well as for Moon Lake located 100 km NNE of Coldwater Lake. However, δ18O records for neither lake are correlated with Mg/Ca records and highlight the importance of knowing the hydrology of each system.

  6. Ostracodes on the Roof of the World: Timing the Uplift of the Tibetan Plateau Using Stable Isotope Paleoaltimetry and Clumped Isotope Paleothermometry

    NASA Astrophysics Data System (ADS)

    Ingalls, M.; Rowley, D. B.; Currie, B. S.; Colman, A. S.

    2014-12-01

    The timing of the uplift of the Tibetan Plateau has occupied the tectonics community for much of the past quarter century. The effort to elucidate the paleoelevation history has refined a more precise method of estimating paleoaltimetry—coupling stable isotopes (oxygen and deuterium; Rowley et al., 2001) with paleotemperatures derived from Δ47 clumped isotope paleothermometry. However, geologists using this method on the Tibetan Plateau are correctly concerned with the preservation of a primary δ18Ow signal in the thermally altered rocks commonly inherent to collisional zones. Burial by both overlying strata and tectonics can lead to thermal alteration and isotopic resetting, eliminating the possibility of constraining the elevation history using the stable isotope record. Lin et al. (2014) suggest preservation of a primary depleted oxygen signal in the 55 My carbonates of the Nianbo Fm. and argue against the previously accepted diagenetic resetting of lacustrine and paleosol carbonates found in the Linzhou (Penbo) Basin. The Lin et al. study reports recovery of seasonal isotopic variation in an ostracode using in situ analysis by NanoSIMS, which suggests the host carbonates have not reached sufficiently high temperatures for resetting of the primary δ18O signal. This result prompted further Δ47 analyses at Chicago of Penbo carbonates initially determined to have high paleotemperatures (>60°C) using older, less-refined clumped isotope techniques five years ago. Results of our clumped isotope study will examine whether or not seasonal δ18Oc variations are preserved in the Nianbo Fm. Δ47-derived paleotemperatures will reveal whether the ostracodes preserve an original oxygen signal or are thermally overprinted. The combination of paleotemperatures and δ18Ow will allow for the paleoelevation history of the Tibetan Plateau to be extended to the Eocene using the robust Δ47-derived paleotemperature proxy.

  7. The nonmarine Lower Cretaceous of the North American Western Interior foreland basin: New biostratigraphic results from ostracod correlations and early mammals, and their implications for paleontology and geology of the basin—An overview

    NASA Astrophysics Data System (ADS)

    Sames, Benjamin; Cifelli, Richard L.; Schudack, Michael E.

    2010-08-01

    The timespan represented by the hiatus between nonmarine Upper Jurassic (Early Berriasian?) and unconformably overlying Lower Cretaceous deposits throughout the North American Western Interior foreland basin has been under discussion for the entire 20th century and remains controversial to date. Ongoing research in revision of Early Cretaceous nonmarine ostracods of some respective North American formations leads to a breakthrough concerning the verification of their biostratigraphic utility as well as their subsequent application. These ostracods are not as endemic as hitherto believed and can be used for supraregional and regional correlation, as well as improvement of the age determination of North American units. New results strongly suggest a maximum age of Late Berriasian to Valanginian (˜ 142-138 Ma) for the lower part of the Lakota (Black Hills area, South Dakota) and Cedar Mountain (Utah) formations. A pre-Aptian maximum age for the Lakota Formation is supported by early mammals. These biostratigraphic results affect the correlatable formations as well, and therefore have broad implications on basin-related geologic and paleontologic topics that are overviewed and discussed herein. The central issue hampering an integrated synthesis of the foreland basin is its yet imprecise chronostratigraphic framework and documentation. Temporal relationships between the gologic processes of the basin and their control factors are still insufficiently calibrated or controversial. Detailed ongoing revision of North American Early Cretaceous nonmarine ostracods demonstrates their applicability, utility, and further potential as tool for improvement of the chronostratigraphy of the Western Interior foreland basin at both small and large scales. These ostracods also foster understanding of animal (e.g. early mammals and dinosaurs) and plant (angiosperms) evolution on the North American continent and show promise of providing age determinations for single-sample horizons in

  8. Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.

    NASA Astrophysics Data System (ADS)

    Mischke, S.; Herzschuh, U.

    2003-04-01

    A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core

  9. A continuous 250,000 yr record of oxygen and carbon isotopes in ostracode and bulk-sediment carbonate from Bear Lake, Utah-Idaho

    USGS Publications Warehouse

    Bright, Jordon; Kaufman, D.S.; Forester, R.M.; Dean, W.E.

    2006-01-01

    Oxygen and carbon isotopes from a continuous, 120-m-long, carbonate-rich core from Bear Lake, Utah-Idaho, document dramatic fluctuations in the hydrologic budget of the lake over the last 250,000 yr. Isotopic analyses of bulk sediment samples capture millennial-scale variability. Ostracode calcite was analyzed from 78 levels, mainly from the upper half of the core where valves are better preserved, to compare the isotopic value of purely endogenic carbonate with the bulk sediment, which comprises both endogenic and detrital components. The long core exhibits three relatively brief intervals with abundant endogenic aragonite (50??10%) and enriched ??18O and ??13C. These intervals are interpreted as warm/dry periods when the lake retracted into a topographically closed basin. We correlate these intervals with the interglacial periods of marine oxygen-isotope stages 1, 5e, and 7a, consistent with the presently available geochronological control. During most of the time represented by the core, the lake was fresher than the modern lake, as evidenced by depleted ??18O and ??13C in bulk-sediment carbonate. ?? 2006 Elsevier Ltd. All rights reserved.

  10. Absolute paleobathymetry of Upper Cretaceous chalks based on ostracodes - Evidence from the Demopolis Chalk (Campanian and Maastrichtian) of the northern Gulf Coastal Plain

    SciTech Connect

    Puckett, T.M. )

    1991-05-01

    The presence of abundant and diverse sighted ostracodes in chalk and marl of the Demopolis Chalk (Campanian and Maastrichtian) in Alabama and Mississippi strongly suggests that the Late Cretaceous sea floor was within the photic zone. The maximum depth of deposition is calculated from an equation based on eye morphology and efficiency and estimates of the vertical light attenuation. In this equation, K, the vertical light attenuation coefficient, is the most critical variable because it is the divisor for the rest of the equation. Rates of accumulation of coccoliths during the Cretaceous are estimated and are on the same order as those in modern areas of high phytoplankton production, suggesting similar pigment and coccolith concentrations in the water column. Values of K are known for a wide range of water masses and pigment concentrations, including areas of high phytoplankton production; thus light attenuation through the Cretaceous seas can be estimated reliably. Waters in which attenuation is due only to biogenic matter-conditions that result in deposition of relatively pure chalk-have values of K ranging between 0.2 and 0.3. Waters rich in phytoplankton and mud-conditions that result in deposition of marl-have K values as great as 0.5. Substituting these values for K results in depth range of 65 to 90 m for deposition of chalk and depth of 35 m for deposition of marl. These depth values suggest that deposition of many Cretaceous chalks and marls around the world were deposited under relatively shallow conditions.

  11. Late Quaternary water depth changes in Hala Lake, northeastern Tibetan Plateau, derived from ostracod assemblages and sediment properties in multiple sediment records

    NASA Astrophysics Data System (ADS)

    Yan, Dada; Wünnemann, Bernd

    2014-07-01

    Late Pleistocene and Holocene climate dynamics along the marginal belt of the East Asian Summer Monsoon in China and their responses to hydrological cycles in lake basins of the Tibetan Plateau are still a matter of scientific discussion. Hala Lake, a closed 65 m deep lake basin in the western Qilian Mountains, Qinghai Province, is considered a monitor of climate-driven hydrological and environmental changes during the past 24 kyr BP. The distribution patterns of ostracod assemblages, stable isotopes, sediment-geochemical properties in four sediment records from different water depths and their combination with the unique limnological setting enabled us to reconstruct four major phases of centennial-scale water depth fluctuations from the global Last Glacial Maximum (ca 24 kyr BP) to the Present. Our results show that Hala Lake experienced a very shallow and small water body during the LGM and Lateglacial under cold and dry climate conditions. Rapid increase of water depth and contemporaneous lake expansion started at around 14 kyr BP (Phase I), most likely as a result of glacier melt due to the onset of climate warming. The lake reached >45 m water depth at around 13.5 kyr BP. Reduced water depth during the Younger Dryas spell (ca 12 kyr BP) may be attributed to a short-term return to cooler and drier conditions. During the early Holocene (Phase II), water depth increased further toward lake highstands close to its present level, with a highest lake level of up to 9 m above the present lakestand at 8.0-7.8 kyr BP. Besides continued glacier melt supply, we assume that summer monsoon effective moisture contributed to the overall water budget, but remained relatively unstable, favoring water depth fluctuations. A pronounced lower water depth falls into the period between 9.2 and 8.1 kyr BP, perhaps the result of weak monsoon influence or its complete absence, although the warming trend continued toward its optimum at ca 8-7 kyr BP. A distinct mass flow, most likely

  12. Late Quaternary Lake History of Hala Lake, Qinghai Province, China, Evidenced by Ostracod Assemblages and Sediment Properties in Multiple Sediment Records

    NASA Astrophysics Data System (ADS)

    YAN, Dada; Wuennemann, Bernd

    2014-05-01

    Hala Lake, a closed 65 m deep lake basin in the western Qilian Mountains, Qinghai Province, is considered a monitor of climate-driven hydrological and environmental changes during the past 24 kyr BP. The distribution patterns of ostracod assemblages, sediment-geochemical properties in four sediment records from different water depths and the unique limnological setting (green algae layer between 25 and 32 m water depth and seasonally anoxic conditions) enabled us to reconstruct four major phases of centennial-scale water depth fluctuations from the global Last Glacial Maximum (ca. 24 kyr BP) to the Present. Our results show that Hala Lake experienced a very shallow and small water body during the LGM and Late Glacial under cold and dry climate conditions. Rapid increase of water depth and contemporaneous lake expansion started at around 15 kyr BP (Phase I), most likely as a result of glacier melt due to the onset of climate warming. The lake reached >45 m water depth at around 13.5 kyr BP, followed by a decline (5-6 m) during the Younger Dryas spell (ca. 12 kyr BP), which may be attributed to a short-term return to cooler and drier conditions. During the early Holocene (Phase II), water depth increased again towards lake highstands close to its present level. Besides continued glacier melt supply, we assume that summer monsoon effective moisture contributed to the overall water budget, but remained relatively unstable, favoring water depth fluctuations of about 10-15 m. A pronounced lower water depth falls into the period between 9 and 8 kyr BP, perhaps the result of weak monsoon influence or its complete absence, although the warming trend continued towards its optimum at ca. 8-7 kyr BP. A distinct mass flow, most likely triggered by an earthquake, occurred during a lake lowstand between 8.1 kyr BP and 7.0 kyr BP. The mid-Holocene (Phase III) was characterized by deepened water between 7.5 and 4.5 kyr BP, interrupted by short-term declines at around 7 and 6

  13. Seasonal Variations in δ18O of Inflowing River Water, Lake Water, Sediment Trap Material and Ostracod Shells of Lake Nam Co and its Catchment (Tibet, China) — a Proxy Calibration Study

    NASA Astrophysics Data System (ADS)

    Daut, G.; Wang, J.; Ju, J.; Plessen, B.; Fürstenberg, S.; Baade, J.; Frenzel, P.; Haberzettl, T.; Maeusbacher, R.; Zhu, L.

    2014-12-01

    δ18O is a very common proxy used in palaeoclimate studies all over the world, but for most parts of the world and especially the Tibetan Plateau modern studies that trace the pathway of this isotope from sink to source are lacking. In this study, financed by the BMBF (German Ministry of Science and Education, Project CADY), we present data that fill this gap. The study was performed in the terminal lake Nam Co, the biggest lake on the central Tibetan Plateau and its catchment. Water of the main tributaries to the lake, lake water at three different stations and from different water depths, bulk carbonate collected from different water depths with sediment traps and shells of living ostracods were collected for one year at lake Nam Co in approx. monthly intervals and analyzed for their δ18O values. The inflowing river waters mainly reflect the precipitation and show regional as well as seasonal variations depending on their location and on Monsoon or Westerly season but are in general on the global meteoric waterline. The lake water shows only minor vertical and spatial variations and is clearly off the meteoric waterline due to strong evaporation effects in this terminal lake. δ18O values of the bulk carbonate of sediment collected in sediment traps show only minor vertical and spatial variations during the year and the δ18O offset compared to the lake water is with around 1 ‰ quite small. Most probably this is attributed to chemical fractionation during formation of monohydrocalcite in the water column. In contrast δ18O values of ostracod shells are significant heavier than the lake water indicating isotopic fractionation (vital effect) during shell formation. In addition a seasonal variability is visible. The data of this proxy calibration study give now for the first time the opportunity to validate δ18O proxy data measured on core material from Lake Nam Co for their palaeoclimatic significance.

  14. Ascosphaera subglobosa, a new species from North America associated with the solitary bee Megachile rotundata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascosphaera is a widespread ascomycetous genus of mostly obligate associates of bees. These fungi have diversified to exploit seemingly every possible substrate available in their bee-associated habitat, occurring as pathogens of the bees, or as saprotrophs on honey, cocoons, nesting materials, poll...

  15. Variability of the intensity of the Tsushima Warm Current and bottom water ventilation in western North Pacific marginal seas during the Pleistocene: Preliminary results from IODP Expedition 346 (Sites U1427 and U1428) based on ostracod assemblages

    NASA Astrophysics Data System (ADS)

    Alvarez Zarikian, Carlos A.; Bassetti, Maria-Angela; Toucanne, Samuel; Sagawa, Takuya; Holbourn, Ann; Yasuhara, Moriaki; Tada, Ryuji; Murray, Richard W.

    2015-04-01

    IODP Expedition 346 drilled Sites U1427 and U1428 in ideal locations to monitor changes in (i) the intensity of the influx of the Tsushima Warm Current (TWC), and (ii) the intermediate bottom water ventilation from a few hundred thousand years to over a million years in the western North Pacific marginal seas. Site U1427 is located at 330 m water depth in the marginal sea bordered by the Eurasian continent, the Korean peninsula and the Japanese Islands. This semi-enclosed marginal sea has an average water depth of 1350 m and is connected with other marginal seas in the region by shallow, narrow straits. Site U1428 is located at 724 m in the East China Sea and this region is more influenced by continental freshwater runoff derived from the Yangtze River. Both sites are in the path of the TWC, a branch of the Kuroshio Current, the only warm current flowing into the marginal sea west of Japan. The TWC carries both water originating from the subtropical North Pacific and fresher runoff water derived from East China Sea continental shelf. The northerly flow of the TWC through the shallow Tsushima Strait is ultimately controlled by relative sea level variations over time. The Japan Sea Intermediate Water (JSIW), found below the TWC between 200 and 400-500 m water depth, corresponds to a vertical salinity minimum, and has relatively high oxygen concentration related to the deep-water convection in winter and linked to fresh water supply during winter monsoon intervals. Recent observations point to variations in the intensity of deep and intermediate water currents during glacials and interglacials, and millennial scale climate cycles, but the mechanisms of such variations are not fully known. Here we present preliminary results based on microfossil faunal (ostracods) and sedimentological (sortable silt) proxies that show variability in the intensity of bottom water circulation and environmental conditions during the Pleistocene. Ostracods (benthic microcrustaceans known

  16. Reply to Discussion: a critique of Possible waterways between the Marmara Sea and the Black Sea in the late Quaternary: evidence from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Geo-Marine Letters, 2011

    NASA Astrophysics Data System (ADS)

    Nazik, Atike; Meriç, Engin; Avşar, Niyazi

    2012-06-01

    In their discussion of our 2011 paper dealing with possible waterways between the Marmara Sea and the Black Sea in the "late" Quaternary, based on data from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Yaltırak et al. (Geo-Mar Lett 32:267-274, 2012) essentially reject the idea of any links whatsoever, be they between the Marmara Sea and the lakes İznik and Sapanca, or further to the Black Sea via the valley of the Sakarya River. The evidence they provide in support of their view, however, is essentially circumstantial, in part conjectural, and also inconclusive considering the findings in favour of linkage between the Marmara Sea and the lakes at the very least, while the proposed connection with the Sakarya River valley remains speculative because of the lack of unambiguous data. On the other hand, Yaltırak et al. (Geo-Mar Lett 32:267-274, 2012) do raise valid points of concern which deserve careful future investigation, the most important being the possibility of sample contamination from dumped marine sediment used for construction purposes along some parts of the shore of Lake İznik. We agree that a concerted multidisciplinary effort is required to address the many unresolved issues in connection with the potential waterways proposed by us and others before us.

  17. Variability of the Tsushima Warm Current during the Pleistocene and its relationship with the evolution of the East Asian Monsoon. Preliminary results from IODP Expedition 346 (Sites U1427 and U1428/29) based on benthic ostracod assemblages.

    NASA Astrophysics Data System (ADS)

    Bassetti, M. A.; Alvarez Zarikian, C. A.; Toucanne, S.; Yasuhara, M.; Holbourn, A. E.; Sagawa, T.; Tada, R.; Murray, R. W.

    2014-12-01

    The semi-enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula and the Japanese Islands has an average depth of 1350 m and is connected with other marginal seas in the region by shallow and narrow straits. At present, the Tsushima Warm Current (TWC), a branch of the Kuroshio Current, is the only warm current flowing into the marginal sea west of Japan. The TWC carries both subtropical water originating from the North Pacific and fresher runoff water derived from East China Sea continental shelf. The northerly flow of the TWC through the shallow Tsushima Straits is ultimately controlled by relative sea level variations over time. IODP Expedition 346 Sites U1427 and U1428/29 are ideally located to record changes in (i) the intensity of the influx of the TWC, and (ii) the intermediate ventilation of the marginal sea over the last million years. The Japan Sea Intermediate Water (JSIW) corresponds to a vertical salinity minimum, found below the TWC, between 200 and 400-500 m water depth. The JSIW shows a relatively high oxygen concentration, related to the deep water convection in winter and linked to fresh water supply during winter monsoon intervals. Based on recent observations, it is thought during glacial and interglacial conditions, and millennial scale climate cycles the intensity of deep and intermediate water currents varied but the mechanisms of such variations are not fully known. Microfossil faunal proxies can be used for tracking bottom environmental conditions related to variability of the bottom water circulation intensity. Here, we present preliminary results obtained using ostracods (benthic microcrustaceans) that are abundant in the sedimentary sequences recovered at Sites U1427 and U1428/29, and are known to react sensitively to changes in water masses physico-chemical parameters. In particular, the variability of the genus Krithe through time is correlated with the sortable silt (carbonate-free, 10-63 µm sediment size

  18. Developmental process of musculoskeletal integration in ostracod antenna.

    PubMed

    Kaji, Tomonari

    2012-03-01

    The functional morphology of arthropod appendages shows remarkable diversity. Plausible functional integrations, particularly between muscles and the exoskeleton, must be achieved in these diverse morphologies. This study provides an insight into the evolutionary pathway of diversified appendages from a functional point of view. The musculoskeletal structure and development of antennae in five species of Cypridocopina were compared. The muscle and skeletal systems are integrated in several ways: The integration in Propontocypris attenuata occurs during various stages of the molting growth, whereas that in Fabaeformiscandona breuili occurs during the myogenesis. These two types of developmental processes have notable similarities, despite their occurrence during different developmental phases. From the overview of the molecular phylogeny presented by earlier studies, it is suggested that the integrated musculoskeletal system has reappeared repeatedly in cypridoid lineages as an atavism. This study demonstrates how arthropod appendages evolve without losing the integrity of the functional whole. PMID:22305643

  19. The Ostracoda assemblage of the Eocene-Oligocene transition in northwestern Thrace: Kırklareli-Edirne area (northwestern Turkey)

    NASA Astrophysics Data System (ADS)

    Şafak, Ümit; Güldürek, Manolya

    2016-05-01

    The aim of the study is to investigate the Eocene-Oligocene transition in detail in northwest Thrace (NW Turkey) with heavy reliance on ostracod fauna. The lithologies formed and the environmental changes during this time period were also studied. The study was carried out in northwest Thrace within the outcropping Koyunbaba, Soğucak, and Ceylan Formations; Mezardere, Osmancık, and Danişmen Formations of the Yenimuhacir Group; and the Taşlısekban and Pınarhisar members of the Danişmen Formation. Rich ostracod fauna indicating an Eocene and Oligocene age and environment are found within these units. The Ostracoda fauna identified were ostracods Triebelina punctata, Bairdia cymbula, Bairdia tenuis, Cyamocytheridea nova, Krithe bartonensis, Krithe angusta, Krithe rutoti, Krithe parvula, Echinocythereis isabenana, Leguminocythereis genappensis, Grinioneis triebeli, Xestoleberis subglobosa and Xestoleberis muelleriana from the Mid-Late Eocene epoch; Cytheromorpha zinndorfi, Hemicyprideis montosa, Neocyprideis williamsoniana, Cladarocythere apostolescui, Hammatocythere hebertiana, Haplocytheridea helvetica, Cytheridea pernota, Callistocythereis vitilis, Cushmanidea cf. scrobiculata, Pterygocythereis fimbriata, Pokornyella limbata, Grinioneis paijenborchiana, Cytheretta tracensis, Macrocypris wrightii and Paracypris bouldnorensis from the Late Eocene-Early Oligocene epoch; and Novocypris eocenana, Novocypris striata, Moenocypris forbesi, Candona (Pseudocandona) fertilis, Candona (Lineocypris) sp. and Cypridopsis soyeri from the Early-Late Oligocene epoch. The study was also correlated to previous research conducted on Eocene-Oligocene age ostracods around the area, in northwestern Europe, and in the Paris-Akiten Basin, in view of similar age-environment relationships determined by said studies. On the basis of evidence from the lithologic content of the beds and the micropaleontological investigation, the fossil community identified in this study indicates that the

  20. Effect of the 'Vesulian events' on the foraminifers and ostracods in the Tethyan oceanic environment

    NASA Astrophysics Data System (ADS)

    Görög, Ágnes; Wernli, Roland; Tóth, Emőke

    2014-05-01

    In the north-western Tethys, at the Early/Late Bajocian boundary the 'Vesulian Unconformity' can be recognized as a result of carbonate crisis caused by transgression, culminating in the late Niortense -early Garantiana zones, followed by cooling and sudden regression. Later, in the Zigzag and Progracilis zones there was a regression causing also first-order crisis in the ammonite fauna. Up to know only the early Bajocian (BARBIERI, 1964; MONOSTORI, 1995; WERNLI and GöRöG, 1999, 2000) and middle - late Bathonian (GöRöG and WERNLI, 2002) microfauna of the Tethyan oceanic realm were studied and we have no information about late Bajocian -early Bathonian interval. The study of the foraminifera and ostracoda fauna from succession of Gyenespuszta, Bakony Mts, Hungary fill the gap of the records about these ages. The succession consists of ammonitico rosso type limestones, deposited on a submarine high. Despite the heavy condensation a relatively complete stratigraphic sequence (4 m) from the late Bajocian Humphresianum Zone up to late Bathonian Retrocostatum Zone could be identified based on ammonites (GALáCZ, 1970, 1980), which is unique in the Tethys. From each of the 18 beds, thin sections were made for microfauna and microfacies studies and the microfauna were extracted by pure acetic acid. In the ostracoda fauna is relative poor (13 species) consisting of smooth bairdids, Paracypris, Bythocypris, Pontocyprella and Polycope species. Several are known only from the Tethyan oceanic environment, while others occurred also in deep sublittoral - bathyal zone of the epicontinental areas. In the foraminifera fauna 55 benthic and 6 plankton protoglobigerinids (Globuligerina oxfordiana, G. bathoniana, G. aff. bathoniana, Conoglobigerina? aff. dagestanica, C.? avariformis forma alta and sphaerica) could be identified. The fauna differs from the epicontinental ones basically in the ratio of the different forms. Throughout the succession the protoglobigerinids (10-70 %), spirillinids (5-80 %) and smooth walled lenticulinids (5-35 %) dominate, the agglutinated, porcelanous and ornamented lagenids are strongly subordinated, oberhauserellids are missing. The largest faunal changes happened in the Niortense-Garantiana zones and at the end of the Zigzag Zone, which reflected in: 1. drastic decreasing (about half) of diversity of the microfauna; 2. negative correlation of the protoglobigerinids and spirillinids: in the Garantiana-early Zigzag zones spirillinids dominate, while in the other part of the succession protoglobigerinids; 3. change in the protoglobigerinids association: the characteristic large sized (up to 400 μm) thick walled (40 μm compare with 8 μm thin walled forms) specimens disappeared in the Niortense-Garantiana zones, the large forms reoccur in the late Zigzag Zone, but with thin wall. Summarizing, the microfauna changes well coincide with the 'Vesulian events': During the transgression phase the existence of the thick walled protoglobigerinids can be interpret as a cortex bearing forms, adapting to the deep water mode of life. After the cooling and the regression these forms disappeared and only the shallow water dweller smaller forms remained. From the late Zigzag Zone a continuous deepening went on indicating by the appearance of the large probably deep dweller protoglobigerinids. Thus the thick walled protoglobigerinids are known only from the late Aalenian up to the Garantiana Zone, and can be use as a good marker for this interval. The microfauna of the Gyenespuszta succession provided the first evidence of the influence of the 'Vesulian events' on the Tethyan oceanic environment.

  1. The ubiquitous ostracode Darwinula stevensoni (Brady and Robertson, 1870), redescription of the species and lectotype designation.

    USGS Publications Warehouse

    Sohn, I.G.

    1987-01-01

    Darwinula stevensoni (Brady and Robertson 1870) is the type species of Darwinula, the ubiquitous living and fossil nonmarine nominate genus of the Darwinulidae and the Darwinulacea. To date, the additional families Darwinuloididae (fossil), Microdarwinulidae (living and fossil), Panxianidae (fossil), and Suchonellidae (fossil) have been referred to the Darwinulacea. A type specimen for D. stevensoni has not been previously designated. In order to stabilize the species, a lectotype is selected from the type series in the Brady collection at The Hancock Museum, Newcastle upon Tyne. The species is redescribed and reillustrated based on the study of the carapace of a paralectotype and also of valves and appendages of specimens from both England and the United States. Living species of Darwinula have a cosmopolitan distribution in fresh and brackish water. Fossil Darwinulacea, documented in the Carboniferous, serve as indicators of continental Paleozoic to Holocene deposits. - Author

  2. Morphology and distribution of pelagic ostracods of the genus Boroecia (Ostracoda: Halocyprididae) in the Central Arctic.

    PubMed

    Chavtur, Vladimir G; Keyser, Dietmar A; Bashmanov, Alexander G

    2015-01-01

    Morphologically similar Boroecia borealis and B. maxima are redescribed from the Central Arctic. Their morphological differences are minor but well defined. Their geographic and vertical distribution is studied based on an extensive body of materials collected by many expeditions in the Arctic Ocean during the period from 1929 to 1993 at the depth range of 0-4000 m. The comparison of the distribution of both species reveals that B. borealis prefers waters of subarctic structure in the Atlantic, and it inhabits waters in the relatively warm Atlantic layer in the Arctic. In contrast, B. maxima is a good indicator of cool Arctic waters. This species is also present in greater depths of the Northern Atlantic, where polar waters penetrate far towards the south. PMID:26623891

  3. Benthic Ostracods of Skogsbergiella (Myodocopina: Cylindroleberididae) from the Southern Ocean.

    PubMed

    Chavtur, Vladimir G; Keyser, Dietmar

    2015-01-01

    Skogsbergiella tetrathrix sp. nov. and S. species A, species of the family Cylindroleberididae are described from the Drake Passage (59°21.97´S - 60°4.27´W to 59°22.55´S - 60°4.01´W, depth 2372-2380 m) and Weddell Sea  (75°49.9´S-27°31.7´W to 74°51.55´S-27°40.3´W, depth 467-475m) respectively. Skogsbergiella tetrathrix sp.nov. is very close to S. macrothrix Kornicker, 1975 but differs by greater size of carapace, 2-jointed rod-shaped organ, lesser number of setae on comb of fifth limb and teeth on combs of seventh limb, and absence of lateral eyes. S. species A is similar to S. skogsbergi Kornicker, 1971 and S. senex Kornicker, 1996 but differs in size and number of setae on the dorsal margin of mandibular basale and seventh limb. PMID:26624764

  4. LANDSCAPE INFLUENCES ON LAKE CHEMISTRY AND OSTRACOD COMMUNITY STRUCTURE OF SMALL DIMICTIC LAKES IN SOUTHERN WISCONSIN DIMICTIC LAKES

    EPA Science Inventory

    The natural land cover patterns that characterize the southern part of Wisconsin are legacies of a

    glaciated past. Land cover pattern and geomorphology control the hydrologic connections between water

    resources and the land by which ecosystems, including lakes are o...

  5. Discussion: a critique of Possible waterways between the Marmara Sea and the Black Sea in the late Quaternary: evidence from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Geo-Marine Letters, 2011

    NASA Astrophysics Data System (ADS)

    Yaltırak, Cenk; Ülgen, Umut B.; Zabcı, Cengiz; Franz, Sven Oliver; Ön, Sena Akçer; Sakınç, Mehmet; Çağatay, M. Namık; Alpar, Bedri; Öztürk, Kurultay; Tunoğlu, Cemal; Ünlü, Selma

    2012-06-01

    The identification of past connection routes between the Black Sea and the Sea of Marmara, other than the traditional one through to the Bosphorus Strait, would be of considerable interest to the international scientific community. Nazik et al. (Geo-Mar Lett 31:75-86 (2011) doi:10.1007/s00367-010-0216-9) suggest the possibility of two alternative waterway connections via lakes Sapanca and İznik. Their Black Sea to Sea of Marmara multi-connection hypothesis, which is based on undated marine fossils collected in both lakes from surficial grab samples, conflicts with many earlier studies. In this contribution, the hypothesis and the underlying data are discussed in the light of previous tectonic, sedimentological and limnological findings showing that it is impossible to have had marine connections through lakes Sapanca and İznik during the last 11.5 ka. Global sea-level trends and tectonic uplift rates would accommodate a connection between the Sea of Marmara and Lake İznik in the middle Pleistocene. Uplift rates for the northern block of the North Anatolian Fault, when compared with the global sea-level curve, clearly indicate that there cannot have been a connection through the İzmit Gulf-Lake Sapanca-Sakarya Valley for at least the past 500 ka. Moreover, borehole sediments along the western shores of Lake Sapanca, which reach down to the bedrock, do not contain any marine fossils.

  6. Ostracoda and paleoceanography

    NASA Astrophysics Data System (ADS)

    Cronin, T. M.; Boomer, I.; Dwyer, G. S.; Rodriguez-Lazaro, J.

    Ostracodes are mainly benthic Crustacea. They are commonly preserved in marine and marginal marine sediments and are used increasingly in Quaternary paleoceanography. The ecological sensitivity of ostracode species to temperature, salinity and dissolved oxygen have allowed paleoceanographic reconstruction of important climate-related variables over timescales ranging from 107 to 102 years. This chapter reviews recent advances in the application of ostracodes to the study of large-scale ocean and climate events caused by Cenozoic tectonic and climate changes with particular reference to Quaternary orbital forcing, thermohaline circulation, decadal and interannual (El Niño-Southern Oscillation) climate variability, and 20th century anthropogenic factors.

  7. Predation of schistosomiasis vector snails by ostracoda (crustacea)

    USGS Publications Warehouse

    Sohn, I.G.; Kornicker, L.S.

    1972-01-01

    An ostracod species of Cypretta is an effective predator in laboratory experiments on 1- to 3-day-old Biomphalaria glabrata, a vector snail of the blood fluke that causes the tropical and subtropical disease schistosomiasis.

  8. Neogene-quaternary Ostracoda and paleoenvironments, of the Limón basin, Costa Rica, and Bocas del Toro basin, Panama

    USGS Publications Warehouse

    Borne, P.F.; Cronin, T. M.; Hazel, J.E.

    1999-01-01

    Tropical marine ostracodes from Neogene and Quaternary sediments of the Central American Caribbean region have been the subject of biostratigraphic, ecological, taxonomic, and evolutionary studies. As part of the Panama Paleontology Project (PPP), Neogene and Quaternary ostracodes are being studied from the Central American region. The overall goal of this research is to evaluate the impact of the emergence of the Central American Isthmus as a land barrier between the Caribbean/tropical Atlantic and the Pacific oceans on marine ostracode biodiversity and the oceanic environments in which extant ostracodes evolved. Due to the ecological specificity of many living tropical ostracode species, they are ideally suited for reconstructing paleoenvironments on the basis of their occurrence in fossil assemblages, which in turn can lead to a better understanding of the tropical climatic and tectonic history of Central America. The principal aims of this chapter are: (a) to document the composition of the ostracode assemblages from the Limón Basin of Costa Rica and the Bocas del Toro Basin of Panama, two areas yielding extensive ma rine ostracode assemblages; (b) to describe the environments of deposition within these basins; and (c) to document the stratigraphic distribution of potentially agediagnostic ostracode species in the Limón and Bocas del Toro basins in order to enhance their use in Central American biostratigraphy. A secondary, but none-the-less important goal is to assemble a database on the distribution of modem ostracode species in the Caribbean and adjacent areas as a basis for comparison with fossil assemblages. Although the ecological, biostratigraphic and paleoenvironmental conclusions presented here will improve as additional material is studied, these fossil and modem ostracode databases constitute the foundation for future evolutionary and geochernical studies of tropical Caribbean and eastern Pacific Ocean ostracodes. Moreover, we present here evidence

  9. Insect pollination and self-incompatibility in edible and/or medicinal crops in southwestern China, a global hotspot of biodiversity.

    PubMed

    Ren, Zong-Xin; Wang, Hong; Bernhardt, Peter; Li, De-Zhu

    2014-10-01

    An increasing global demand for food, coupled with the widespread decline of pollinator diversity, remains an international concern in agriculture and genetic conservation. In particular, there are large gaps in the study of the pollination of economically important and traditionally grown species in China. Many plant species grown in China are both edible and used medicinally. The country retains extensive written records of agricultural and apicultural practices, facilitating contemporary studies of some important taxa. Here, we focus on Yunnan in southwestern China, a mega-biodiversity hotspot for medicinal/food plants. We used plant and insect taxa as model systems to understand the patterns and consequences of pollinator deficit to crops. We identified several gaps and limitations in research on the pollination ecology and breeding systems of domesticated taxa and their wild relatives in Yunnan and asked the following questions: (1) What is known about pollination systems of edible and medicinal plants in Yunnan? (2) What are the most important pollinators of Codonopsis subglobosa (Campanulaceae)? (3) How important are native pollinator species for maximizing yield in Chinese crops compared with the introduced Apis mellifera? We found that some crops that require cross-pollination now depend exclusively on hand pollination. Three domesticated crops are dependent primarily on the native but semidomesticated Apis cerana and the introduced A. mellifera. Other species of wild pollinators often play important roles for certain specialty crops (e.g., Vespa velutina pollinates Codonopsis subglobosa). We propose a more systematic and comprehensive approach to applied research in the future. PMID:25326615

  10. Antifouling properties of hydrogels

    NASA Astrophysics Data System (ADS)

    Murosaki, Takayuki; Ahmed, Nafees; Gong, Jian Ping

    2011-12-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.

  11. Population and life-stage specific sensitivities to temperature and salinity stress in barnacles.

    PubMed

    Nasrolahi, Ali; Havenhand, Jonathan; Wrange, Anna-Lisa; Pansch, Christian

    2016-01-01

    Temperature and salinity shape the distribution and genetic structure of marine communities. Future warming and freshening will exert an additional stress to coastal marine systems. The extent to which organisms respond to these shifts will, however, be mediated by the tolerances of all life-stages and populations of species and their potential to adapt. We investigated nauplius and cypris larvae of the barnacle Balanus (Amphibalanus) improvisus from the Swedish west coast with respect to temperature (12, 20, and 28 °C) and salinity (5, 15, and 30) tolerances. Warming accelerated larval development and increased overall survival and subsequent settlement success. Nauplii developed and metamorphosed best at intermediate salinity. This was also observed in cypris larvae when the preceding nauplii stages had been reared at a salinity of 30. Direct comparisons of the present findings with those on a population from the more brackish Baltic Sea demonstrate contrasting patterns. We conclude that i) B. improvisus larvae within the Baltic region will be favoured by near-future seawater warming and freshening, that ii) salinity tolerances of larvae from the two different populations reflect salinities in their native habitats, but are nonetheless suboptimal and that iii) this species is generally highly plastic with regard to salinity. PMID:27582433

  12. Population and life-stage specific sensitivities to temperature and salinity stress in barnacles

    PubMed Central

    Nasrolahi, Ali; Havenhand, Jonathan; Wrange, Anna-Lisa; Pansch, Christian

    2016-01-01

    Temperature and salinity shape the distribution and genetic structure of marine communities. Future warming and freshening will exert an additional stress to coastal marine systems. The extent to which organisms respond to these shifts will, however, be mediated by the tolerances of all life-stages and populations of species and their potential to adapt. We investigated nauplius and cypris larvae of the barnacle Balanus (Amphibalanus) improvisus from the Swedish west coast with respect to temperature (12, 20, and 28 °C) and salinity (5, 15, and 30) tolerances. Warming accelerated larval development and increased overall survival and subsequent settlement success. Nauplii developed and metamorphosed best at intermediate salinity. This was also observed in cypris larvae when the preceding nauplii stages had been reared at a salinity of 30. Direct comparisons of the present findings with those on a population from the more brackish Baltic Sea demonstrate contrasting patterns. We conclude that i) B. improvisus larvae within the Baltic region will be favoured by near-future seawater warming and freshening, that ii) salinity tolerances of larvae from the two different populations reflect salinities in their native habitats, but are nonetheless suboptimal and that iii) this species is generally highly plastic with regard to salinity. PMID:27582433

  13. Zooplankton diversity of Chikkadevarayana canal in relation to physico-chemical characteristics.

    PubMed

    Smitha; Shivashankar, P; Venkataramana, G V

    2013-07-01

    Plankton diversity and physico-chemical parameters are an important criterion for evaluating the suitability of water for irrigation and drinking purposes. In this study, we tried to assess zooplankton species richness, diversity and evenness to predict the state of Chickadevarayana canal water of Cauvery River according to physico-chemical parameters. A total of 51 taxa were recorded with 22 rotifers, 5 copepods, 6 cladocerans, 1 ostracoda and 17 protozoans. More number of zooplankton species were recorded in Darasaguppe (30) followed by Edmuri (26), Kennala (20), Pandavpura (19) and Gendehosahalli (16). Among the rotifers, Euchlanis sp. species was abundant (194). Acantholeberis curvirostris was predominant among cladocerans (970). Among copepods, numerical superiorities were found in the case Cyclops sp. Cypris sp. was recorded in the ostracoda. Centropyxis aculeate repeated abundance in protozoans (412). The water samples analyzed for temperature, pH, electrical conductivity, alkalinity, hardness, dissolved oxygen, phosphate, sulphate and nitrate did not indicate variation. The occurrence of Asplanchna herricki, Lacrymaria sp, Brachionus pala and Monostyla lunaris showed highest similarity of occurrence reaching above 90%. The study revealed that the presence of certain species like Monostyla, Lepadella, Leydigia, Keratella, Branchionus and Cypris species can be considered as a biological indicator for eutrophication. PMID:24640263

  14. Four Newly Recorded Amanita Species in Korea: Amanita sect. Amanita and sect. Vaginatae

    PubMed Central

    Kim, Chang Sun; Jo, Jong Won; Kwag, Young-Nam; Oh, Junsang; Shrestha, Bhushan

    2013-01-01

    We collected nearly 70 specimens of Amanita species during a diversity study of Korean mushrooms conducted in 2012. In this study, we primarily investigated 23 Amanita specimens belonging to sections Amanita and Vaginatae. Based on sequence data of the internal transcribed spacers and partial large subunit of ribosomal RNA and morphological characteristics, we identified the following 15 phylogenetic species: A. alboflavescens, A. ceciliae, A. farinosa, A. fulva, A. griseofolia, A. ibotengutake, A. melleiceps, A. orientifulva, A. pantherina, A. rubrovolvata, A. sinensis, A. subglobosa, A. vaginata, A. cf. vaginata f. alba, and an undescribed Amanita species. In this study, four of the identified Amanita species (A. griseofolia, A. ibotengutake, A. orientifulva, and A. sinensis) were reported for the first time in Korea. PMID:24198667

  15. Miocene foraminifera from DSDP site 272, Ross Sea

    SciTech Connect

    Steinhauff, D.M. ); Webb, P.N. )

    1987-01-01

    At site 272 a major decrease in foraminiferal abundance and diversity is noted between approximately 138 and 148 meters subbottom. This roughly corresponds to the subunit 2A/2B boundary and occurs at the level of a proposed 4-million-year hiatus which separates Lower and Middle Miocene sediments. Only sporadic occurrences of robust thick-walled forms such as Islandiella spp., Epistominella exigua, Globocassidulina subglobosa, and Nonionella iridea occur below 147 meters (in subunit 2B) and much of the lower succession is barren of foraminifera. Absence of fauna is attributed to dissolution contemporaneous with deposition, or post-depositional diagenesis. Site 272 foraminiferal assemblages may have been subjected to glacial transport and redeposition and/or bottom current reworking. The wide size range of foraminifera at any stratigraphic level suggests size sorting is not a significant factor.

  16. Testing for possible cyclicity in carbonate sediments of Middle Ordovician of east Tennessee

    SciTech Connect

    Ghazizadeh, M.; Walker, K.R.

    1986-05-01

    Middle Ordovician carbonate sediments (Chickamauga Group) near Decatur, Tennessee, consist of 450 m of complex tidal-flat and subtidal sediments. Fourteen facies are recognized: (1) cherty dolostone (supratidal environment); (2) green and red silty mudstone (supratidal mud flat); (3) greenish-gray micrite-biomicrite (supratidal mud flat); (4) red silty, intrapelbiosparite-biosparite (intertidal channel); (5) green and red, loosely packed, ostracod-rich pelbiomicrite (intertidal pond); (6) stromatolitic mudstone (intertidal levee); (7) bryozoan-ostracod-brachiopod-rich pelbiomicrite (subtidal lagoon type I); (8) silty, packed pelbiomicrite-pelbiosparite (subtidal lagoon type II); (9) ostracod-gastropod-rich, bioturbated pelbiomicrite (subtidal lagoon type III); (10) bioturbated brachiopod-molluscan-rich biomicrite (subtidal lagoon type IV); (11) bioturbated green and red silty mudstone to silty sparse biomicrite (lagoon); (12) gray-tan mudstone to sparse biomicrite (quiet water, deeper subtidal lagoon); (13) intrapelbiosparite-pelbiosparite (subtidal channel); and (14) Tetradium-rich packstone (subtidal wave baffle).

  17. Early Oligocene benthic foraminifera and its response to paleoceanographic changes in the eastern Equatorial Pacific (IODP Exp 320 Site U1334)

    NASA Astrophysics Data System (ADS)

    Takata, H.; Lee, J.; Tsujimoto, A.; Nomura, R.; Khim, B.

    2012-12-01

    We report biotic response of benthic foraminifera to the paleoceanographic changes in the early part of the Early Oligocene (33.2-32.0 Ma), based on faunal analysis of fossil benthic foraminifera and geochemical analysis of bulk sediments at IODP Exp. 320 Site U1334 (the eastern equatorial Pacific). Carbonate content was slightly low from 33.0-32.2 Ma, whereas biogenic opal content was relatively high with fluctuations in this interval. Slightly high opal-MAR and basically constant carbonate-MAR from 33.0-32.2 Ma indicate that geochemical signature of bulk sediments was related to increasing biogenic opal production. The benthic foraminifera accumulation rate (BFAR) was generally constant by ~33 Ma, whereas it was highly fluctuated in the high opal-MAR period. Glogocassidulina subglobosa (moderate food supply with its some seasonality) was lower in the early part of the Early Oligocene than in the late part of the Early Oligocene. However, this species increased temporally in the high opal-MAR period. Occurrence of G. subglobosa implies that biogenic opal production was enhanced temporally with some seasonality. Nuttallides umbonifer (Southern Component Water possibly with slight carbonate corrosiveness or low food supply) was common at around 33.0 Ma, whereas Oridorsalis umbonatus (various trophic condition) occurred frequently in the 33.5-32.0 Ma. Alternation of these two species was repeated in the late part of the Early Oligocene in the abyssal eastern Equatorial Pacific (Takata et al., in review), but such pattern was obscure in the early part of the Early Oligocene. Antarctic Circumpolar Current became significant since the late Oligocene, but it was not likely strong in the Early Oligocene (Katz et al., 2011). Such paleoceanographic changes might be related to the faunal changes of benthic foraminifera in the eastern equatorial Pacific.

  18. The effect of primary productivity and seasonality on the distribution of deep-sea benthic foraminifera in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Sun, Xichun; Corliss, Bruce H.; Brown, Christopher W.; Showers, William J.

    2006-01-01

    Deep-sea benthic foraminifera from 43 Holocene core tops in the North Atlantic were studied to evaluate the influence of primary productivity and the seasonality of primary productivity on the distributional patterns of species, faunal assemblages, and microhabitat groups. Two faunal assemblages, Epistominella exigua- Alabaminella weddellensis assemblage and Globocassidulina subglobosa- Epistominella umbonifera assemblage, were found to correlate with seasonality of primary productivity. The E. exigua- A. weddellensis assemblage is found at high latitudes and positively correlates with seasonality, while the G. subglobosa- E. umbonifera assemblage is generally found at low latitudes and has a negative correlation. Correlation analysis indicates that the relative abundance of one species alone ( E. exigua or A. weddellensis) is not a strong indicator of either primary productivity or seasonality. No significant relationships are found between benthic foraminiferal species, faunal assemblages, or microhabitat groups and bottom water properties, which suggests that the deep-sea fauna may not be used to reconstruct bottom water properties in this region. Based on microhabitat preferences of individual species, the fauna is categorized into epifaunal, infaunal, and phytodetrital groups and is compared with primary productivity of the overlying surface waters and seasonality. No significant relationship was found between the relative abundance of the infaunal group and primary productivity or its seasonality, and only a weak correlation was found between these variables and the epifaunal group ( r2=0.33; 0.46). However, the relative abundances of the phytodetrital group correlate relatively well with seasonal variability (r2=0.63), reflecting the association of these species with phytodetritus in regions marked by high seasonal variation in organic carbon flux. These results indicate that the relative abundance of the phytodetrital group may be used to reconstruct

  19. Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages.

    PubMed

    Eichler, P P B; Rodrigues, A R; Eichler, B B; Braga, E S; Campos, E J D

    2012-08-01

    More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer. PMID:23011301

  20. Climatic forcing of Quaternary deep-sea benthic communities in the North Pacific Ocean

    USGS Publications Warehouse

    Yasuhara, Moriaki; Hunt, G.; Cronin, T. M.; Hokanishi, N.; Kawahata, H.; Tsujimoto, Akira; Ishitake, M.

    2012-01-01

    There is growing evidence that changes in deep-sea benthic ecosystems are modulated by climate changes, but most evidence to date comes from the North Atlantic Ocean. Here we analyze new ostracod and published foraminiferal records for the last 250,000 years on Shatsky Rise in the North Pacific Ocean. Using linear models, we evaluate statistically the ability of environmental drivers (temperature, productivity, and seasonality of productivity) to predict changes in faunal diversity, abundance, and composition. These microfossil data show glacial-interglacial shifts in overall abundances and species diversities that are low during glacial intervals and high during interglacials. These patterns replicate those previously documented in the North Atlantic Ocean, suggesting that the climatic forcing of the deep-sea ecosystem is widespread, and possibly global in nature. However, these results also reveal differences with prior studies that probably reflect the isolated nature of Shatsky Rise as a remote oceanic plateau. Ostracod assemblages on Shatsky Rise are highly endemic but of low diversity, consistent with the limited dispersal potential of these animals. Benthic foraminifera, by contrast, have much greater dispersal ability and their assemblages at Shatsky Rise show diversities typical for deep-sea faunas in other regions. Statistical analyses also reveal ostracod-foraminferal differences in relationships between environmental drivers and biotic change. Rarefied diversity is best explained as a hump-shaped function of surface productivity in ostracods, but as having a weak and positive relationship with temperature in foraminifera. Abundance shows a positive relationship with both productivity and seasonality of productivity in foraminifera, and a hump-shaped relationship with productivity in ostracods. Finally, species composition in ostracods is influenced by both temperature and productivity, but only a temperature effect is evident in foraminifera. Though

  1. Lake level changes in Hala Lake(NW China) based on ostracodassemblages during the LGM and Post-LGM

    NASA Astrophysics Data System (ADS)

    Yan, D.; Wuennemann, B.

    2012-12-01

    The Hala Lake, located in the Qilian Mountains, Qinghai Province, China, at 4078 m a.s.l. may archive in its sediments hydrological and climate changes during the Late Quaternary time, as it is close to the area impacted by the East-Asian Summer monsoon and westerly-driven air masses. Based on the sediment core H7, which was taken in the center of the lake at 65m water depth,ostracod assemblages and stable isotopes from ostracode shells were investigated in details. Three main species were found, which are common species in high altitude saline lakes of the Tibetan Plateau: Leucocythere sp.,Limnocythereinopinata and Eucypris sp.They started to occur in deeper part of H7,indicating an early onset of favorable living conditions during the LGM and post-LGM periods. Besides, algae occurred between 25 and 32m water depth. According to the unevenly distributed amount of ostracods and oxygen isotope data, our results indicate important lake level changes during the global LGM and Lateglacial. The lake experienced lowest levels of 25-50 m below the present water line. Ostracods disappeared with the onset of the early Holocene.A stepwise refilling started already at ca. 16 kyr BP and reached -25 m level during the Bølling/Allerød warm phase at ca. 13.5 kyr BP.Latest at ca.7.6 kyr BP, the lake reached a stable highstand similar to the present level until ca.6 kyr BPas . The subsequent lake development remains unclear due to strong mismatches of the data but may indicate a general trend to deteriorating conditions and lake level lowstands at ca. 5.0-4.2, 2.0 and at around 0.5 kyr BP.; Ostracods Distribution in H2 ; Ostracods plate in Hala lake

  2. Brilliant iridescence of Morpho butterfly wing scales is due to both a thin film lower lamina and a multilayered upper lamina.

    PubMed

    Giraldo, M A; Stavenga, D G

    2016-05-01

    Butterflies belonging to the nymphalid subfamily, Morphinae, are famous for their brilliant blue wing coloration and iridescence. These striking optical phenomena are commonly explained as to originate from multilayer reflections by the ridges of the wing scales. Because the lower lamina of the scales of related nymphalid butterflies, the Nymphalinae, plays a dominant role in the wing coloration, by acting as a thin film reflector, we investigated single blue scales of three characteristic Morpho species: M. epistrophus, M. helenor and M. cypris. The experimental data obtained by spectrophotometry, scatterometry and scanning electron microscopy demonstrated that also in the Morpho genus the lower lamina of both the cover and ground scales acts as an optical thin film reflector, contributing importantly to the blue structural coloration of the wings. Melanin pigment has a contrast-enhancing function in a sub-class of ground scales. PMID:27072662

  3. Passage of Tropical Storm Allison (2001) over southeast Texas recorded in δ18O values of Ostracoda

    NASA Astrophysics Data System (ADS)

    Lawrence, James R.; Hyeong, Kiseong; Maddocks, Rosalie F.; Lee, Kwang-Sik

    2008-09-01

    Freshwater Ostracoda collected in ephemeral pond-waters derived from Tropical Storm Allison (2001, Texas) recorded the unusually low oxygen-isotope values of that storm. Therefore, the potential clearly exists, in locations where tropical cyclones make landfall, to obtain a long-term record of tropical cyclone activity from fossil ostracode calcite.

  4. Description of a species of Fabaeformiscandona (Ostracoda, Crustacea) from Kushiro Marsh, Hokkaido, Japan, with the nearly complete mitochondrial genomic sequence

    PubMed Central

    Hiruta, Shin-ichi

    2015-01-01

    Abstract Background So far, 16 species of non-marine ostracods have been reported from Kushiro Marsh, Kushiro Shitsugen National Park, eastern Hokkaido, Japan (Hiruta and Smith 2001, Smith and Hiruta 2004). Nine of these species are in Candonidae, the second-most diverse family of non-marine ostracods. This family contains ca. 550 species, or around 25% of the total number of non-marine ostracod species (Martens et al. 2008). New information We sampled ostracods in Kushiro Marsh on 27 December 2012 and identified an undescribed species in the family Candonidae, herein described as Fabaeformiscandona kushiroensis sp. nov. This species belongs to the F. acuminata species group and is characterized by the shapes of the elongate, dorsally directed medial and outer lobes on the distal end of each hemipenis. We also determined for this species the sequence of the nearly complete mitochondrial genome, the first record from the order Podocopa. The genome (ca. 17 kbp) contains two ribosomal RNA, 22 transfer RNA, and 13 protein-coding genes, as also found in other arthropods for which the mitochondrial genome has been sequenced. The gene arrangement is similar to the pancrustacean ground pattern, except that in the control region there is an approximately 2 kbp tandem repeat region composed of 220-bp motif sequences. We describe the genetic features of the mitochondrial genome, including nucleotide composition and the secondary structures of tRNAs and rRNAs, and compare them with the genome of Vargula hilgendorfii (Myodocopa, Ostracoda). PMID:26751633

  5. Biostratigraphic correlation of Pleistocene marine deposits and sea levels, Atlantic coastal plain of the southeastern United States

    USGS Publications Warehouse

    Cronin, T. M.

    1980-01-01

    Marine ostracodes from 50 localities were studied to determine the age and elevation of Pleistocene sea levels in the Atlantic coastal plain from Maryland to northern Florida. Using ostracode taxon and concurrent ranges, published planktic biostratigraphic, paleomagnetic, and radiometric data, ostracode assemblage zones representing early (1.8-1.0 my), middle (0.7-0.4 my), and late (0.3-0.01 my) Pleistocene deposition were recognized and used as a basis for correlation. Ostracode biofacies signifying lagoonal, oyster bank, estuarine, open sound, and inner sublittoral environments provided estimated ranges of paleodepths for each locality. From these data the following minimum and maximum Pleistocene sea-level estimates were determined for the southeastern coastal plain: late Pleistocene, 2-10 m from Maryland to northern Florida; middle Pleistocene, 6-15 m in northern South Carolina; early Pleistocene, 4-22 m in central North Carolina, 13-35 m in southern North Carolina, and 6-27 m in South Carolina. Climatically induced glacio-eustatic sea-level fluctuations adequately account for the late Pleistocene sea-level data, but other factors, possibly differential crustal uplift, may have complicated the early Pleistocene record. ?? 1980.

  6. 77 FR 9618 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-17

    ... Fish and Wildlife Service 50 CFR Part 17 Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Thermophilic Ostracod as Endangered or Threatened AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of 90-day petition finding. SUMMARY: We, the U.S. Fish and...

  7. Transcriptomic Analysis of Neuropeptides and Peptide Hormones in the Barnacle Balanus amphitrite: Evidence of Roles in Larval Settlement

    PubMed Central

    Yan, Xing-Cheng; Chen, Zhang-Fan; Sun, Jin; Matsumura, Kiyotaka; Wu, Rudolf S. S.; Qian, Pei-Yuan

    2012-01-01

    The barnacle Balanus amphitrite is a globally distributed marine crustacean and has been used as a model species for intertidal ecology and biofouling studies. Its life cycle consists of seven planktonic larval stages followed by a sessile juvenile/adult stage. The transitional processes between larval stages and juveniles are crucial for barnacle development and recruitment. Although some studies have been conducted on the neuroanatomy and neuroactive substances of the barnacle, a comprehensive understanding of neuropeptides and peptide hormones remains lacking. To better characterize barnacle neuropeptidome and its potential roles in larval settlement, an in silico identification of putative transcripts encoding neuropeptides/peptide hormones was performed, based on transcriptome of the barnacle B. amphitrite that has been recently sequenced. Potential cleavage sites andstructure of mature peptides were predicted through homology search of known arthropod peptides. In total, 16 neuropeptide families/subfamilies were predicted from the barnacle transcriptome, and 14 of them were confirmed as genuine neuropeptides by Rapid Amplification of cDNA Ends. Analysis of peptide precursor structures and mature sequences showed that some neuropeptides of B. amphitrite are novel isoforms and shared similar characteristics with their homologs from insects. The expression profiling of predicted neuropeptide genes revealed that pigment dispersing hormone, SIFamide, calcitonin, and B-type allatostatin had the highest expression level in cypris stage, while tachykinin-related peptide was down regulated in both cyprids and juveniles. Furthermore, an inhibitor of proprotein convertase related to peptide maturation effectively delayed larval metamorphosis. Combination of real-time PCR results and bioassay indicated that certain neuropeptides may play an important role in cypris settlement. Overall, new insight into neuropeptides/peptide hormones characterized in this study shall

  8. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    SciTech Connect

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M.

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  9. Probing biofouling resistant polymer brush surfaces by atomic force microscopy based force spectroscopy.

    PubMed

    Schön, Peter; Kutnyanszky, Edit; ten Donkelaar, Bas; Santonicola, M Gabriella; Tecim, Tugba; Aldred, Nick; Clare, Anthony S; Vancso, G Julius

    2013-02-01

    The protein repellency and biofouling resistance of zwitterionic poly(sulfobetaine methacrylate)(pSBMA) brushes grafted via surface initiated polymerization (SIP) from silicon and glass substrata was assessed using atomic force microscopy (AFM) adherence experiments. Laboratory settlement assays were conducted with cypris larvae of the barnacle Balanus amphitrite. AFM adherence includes the determination of contact rupture forces when AFM probe tips are withdrawn from the substratum. When the surface of the AFM tip is modified, adherence can be assessed with chemical specifity using a method known as chemical force microscopy (CFM). In this study, AFM tips were chemically functionalized with (a) fibronectin- here used as model for a nonspecifically adhering protein - and (b) arginine-glycine-aspartic acid (RGD) peptide motifs covalently attached to poly(methacrylic acid) (PMAA) brushes as biomimics of cellular adhesion receptors. Fibronectin functionalized tips showed significantly reduced nonspecific adhesion to pSBMA-modified substrata compared to bare gold (2.3±0.75 nN) and octadecanethiol (ODT) self-assembled monolayers (1.3±0.75 nN). PMAA and PMAA-RGD modified probes showed no significant adhesion to pSBMA modified silicon substrata. The results gathered through AFM protein adherence studies were complemented by laboratory fouling studies, which showed no adhesion of cypris larvae of Balanus amphitrite on pSBMA. With regard to its unusually high non-specific adsorption to a wide variety of materials the behavior of fibronectin is analogous to the barnacle cyprid temporary adhesive that also binds well to surfaces differing in polarity, charge and free energy. The antifouling efficacy of pSBMA may, therefore, be directly related to the ability of this surface to resist nonspecific protein adsorption. PMID:23138001

  10. The stratigraphy and palaeoenvironment of the Bathonian "Great Oolite Group" of Woodeaton Quarry, Oxfordshire.

    NASA Astrophysics Data System (ADS)

    Guthrie, Ronald; Stukins, Stephen; Raub, Tim

    2014-05-01

    Woodeaton Quarry, Oxfordshire, represents the most continuously exposed section of the Upper Bathonian 'Great Oolite Group' in the United Kingdom. Like most of the British Bathonian, it is lacking in reliable ammonite zonation from which to define a chronostratigraphy. The sedimentology of the succession can be broken up into two broad facies types: A clay rich, brackish lagoonal environment with intermixed freshwater-influenced flora and fauna; A marginal marine calcareous succession of an oolitic nature with periodic mud-drape intervals. The marginal marine depositional setting, the completeness of the Upper Bathonian stratigraphy and lack of biostratigraphically important macrofauna has motivated this study into the micropalaeontology of Woodeaton. The primary aims of this study are to use foraminifera and ostracods to reconstruct the palaeoenvironments and to refine the biostratigraphy of the Upper Bathonian. The studied succession commences at the top of the Taynton Limestone Formation, which fines upwards into the clay-rich Rutland Formation. Several species of marine ostracods known from the Mid-Upper Bathonian are recovered from the base of the Rutland Formation, such as Praeschuleridea confossa and Angliaecytherldea calvata, as well as fragments of fish scales and elasmobranch teeth. Freshwater influence is evident further up the Rutland Formation where freshwater charophytes, nested bivalves and ostracods of the genus Bisulcocypris have been found. The progression from the Rutland Formation's marine base into the freshwater influenced clays is clear from the varied micropalaeontological fauna. A return to marine conditions in the overlying White Limestone Formation can be observed through the increasing number of benthic foraminiferal taxa - with Spirillina and Lenticulina the most abundant - compared to the Rutland Formation. Within the Shipton and Ardley Members there are also indicative marine ostracod taxa present (including Acanthocythere

  11. Ostracoda (Arthropoda, Crustacea) in a Miocene oxygen minimum zone, Trinidad, West Indies: A test of the Platycopid Signal Hypothesis

    NASA Astrophysics Data System (ADS)

    Wilson, Brent; Coimbra, João C.; Hayek, Lee-Ann C.

    2014-10-01

    Studies of Recent ostracodes around the area of South America shed little light on the paleoenvironmental interpretation of Miocene assemblages. Consequently, interpretations of the Miocene ostracode assemblages must be supplemented using evidence from better documented taxa. Benthic foraminifera in samples from the Lower to Middle Miocene Brasso Formation at Brasso Village, Trinidad, have previously been used to distinguish three sample groupings (Beneath, Within and Above) around an oxygen minimum zone (OMZ), this being a layer of water within which dissolved oxygen concentrations can be as low as 0.1-1.0 mL/L. Using these same samples and the foraminiferal assemblage demarcations relative to the OMZ, this paper examines the associated and rich ostracode fauna of the Brasso Formation. The mean recovery of ostracode valves per sample was approximately three times greater in the Within OMZ sample group than in either of the Beneath OMZ or Above OMZ groups, perhaps reflecting the exclusion of macro-predators from within the OMZ. Individual rarefaction of species richness S to N = 300 valves was conducted for each sample group. This showed that S did not differ between the sample groups, ranging from 22.4 to 24.8. We used all ostracode species to model group separation. Based upon the Mahalanobis' criterion, we obtained significant group separation using a model with four taxa: Munseyella ex gr. minuta, Argilloecia posterotruncata, Munseyella sp. and Xestoleberis sp., while a fifth, Argilloecia spp., provided a significant but minor increase in separation probabilities over all groups. The two most abundant species (Bradleya sp., Gangamocytheridea reticulata) were thus not the best species for detecting the OMZ. Platycopid ostracodes of the genus Cytherella were found throughout the section, rather than concentrated within the OMZ, which contradicts the Platycopid Signal Hypothesis that OMZs are characterized by platycopid dominance. The total distribution and

  12. Biogeography of deep-sea wood fall, cold seep and hydrothermal vent Ostracoda (Crustacea), with the description of a new family and a taxonomic key to living Cytheroidea

    NASA Astrophysics Data System (ADS)

    Karanovic, Ivana; Brandão, Simone Nunes

    2015-01-01

    Stimulated by finding a novel cytheroid ostracod in a piece of sunken wood retrieved from the sea-bed in the Kuril-Kamchatka Trench, we have reviewed all previously published data on ostracods from similarly ephemeral deep-sea habitats (wood falls, hydrothermal vents and cold seeps). These data are placed in the context of all data on living, deep-sea ostracods from other environments. We confirm previous authors' conclusions that faunas from these ephemeral habitats are similar at the generic level, and include elements common to shallow and deep habitats. However, at the species level, endemism varies from zero at cold seeps, to 35% in wood falls and 60% at hydrothermal vents, which is an indication of the relative longevity of these habitats. Non-endemic species occur also in oligotrophic, deep-sea sediments but not in shallow environments. This is in contradiction to previous assumptions that these ephemeral faunas share more species and with shallow habitats than genera with the oligotrophic, deep-sea sediments. We agree with previous authors that the dispersal strategy of wood fall, vent and seep ostracods includes hitchhiking and we propose that it also includes the ability to survive ingestion by larger, more motile animals. The homogeneity of the faunas from ephemeral habitats collected off the American continent is in stark contrast to the highly endemic fauna found in Northwestern Pacific. This suggests that the ostracods may have biogeographical patterns similar to those previously proposed for other groups of benthos. However, any proposal for a global biogeographical scheme for ostracod distributions will have to await far more comprehensive coverage from presently unstudied regions. Finally, we describe and name a novel species of ostracod from the wood fall collected at a depth of 5229 m in the abyss east to the Kuril-Kamchatka Trench, Northwestern Pacific; erecting a new family Keysercytheridae fam. nov. and a new genus, Keysercythere gen. nov., to

  13. Environmental impact assessment of sediment dumping in the southern Baltic Sea using meiofaunal indicators

    NASA Astrophysics Data System (ADS)

    Frenzel, Peter; Borrmann, Corinna; Lauenburg, Beate; Bohling, Björn; Bartholdy, Jan

    2009-02-01

    An experimental sediment dumping was carried out in the southern part of the Mecklenburg Bight in June 2001. Foraminiferans and ostracods from superficial sandy sediment were studied in a time series from before dumping until March 2004 in order to assess changes in associations and recolonization patterns of both groups. Additionally, an area sampling covering the dumping site and its surroundings from 15.5 to 20.7 m water depth made it possible to compare associations inside and outside the dumping area as well as the water depth dependent distribution of foraminiferans and ostracods. Salinity values vary within the high alpha-mesohaline and low polyhaline range. The dominating species are Ammotium cassis (Foraminifera) and Sarsicytheridea bradii (Ostracoda). The diversity is low (Fisher alpha index from 0.4 to 3.2 for foraminiferans and 1.0 to 2.5 for ostracods), but higher within the dumping site samples. These higher values are explainable by input of allochthonous tests and valves representing additional species. After the sediment dumping it took two and a half years to re-establish the total foraminiferan association and the total foraminifer/ostracod ratio within the dumping site. Total foraminiferan abundance increases remarkably with water depth (mean 83 tests in 100 ml) driven by higher nutrient availability and more suitable salinity and temperature values within the zone of the oscillating halocline. The distribution of shallow water species such as Cribroelphidium excavatum, Eucythere argus and Hirschmannia viridis, within the transient water layer A. cassis, Nodulina dentaliniformis, S. bradii and Palmoconcha laevata and below Eggerella scabra indicate the depth position of the halocline. Water depth and sediment dumping influence are the main driving factors for the distribution of foraminifer and ostracod associations within the study area. However, a significant sedimentological difference between samples inside and outside the dumping area is

  14. Empirical calibration of shell chemistry of Cyprideis torosa (Jones, 1850) (Crustacea: Ostracoda)

    NASA Astrophysics Data System (ADS)

    Marco-Barba, J.; Ito, E.; Carbonell, E.; Mesquita-Joanes, F.

    2012-09-01

    Cyprideis torosa is a species of ostracode that inhabits a wide range of aquatic habitats in which its low Alk/Ca requirement is met. Its fossil remains are widely used in palaeoecological studies of coastal environments and inland salt lakes. We collected C. torosa from 20 water bodies near Valencia, Spain. Temperature, chlorophyll a concentration, electrical conductivity, and the concentration of major ions and oxygen isotopes were measured at each site. Between 2 and 20 live individuals of C. torosa were collected per site, their instar stage and sex determined and their shell chemistry (Mg/Ca, Sr/Ca and carbon and oxygen isotope composition) analyzed. Three of these sites were sampled monthly for one year, and ostracode population structure and shell chemistry (20-40 shells) were analyzed. The water chemistry varied widely between sites. TDS (total dissolved solids) ranged from 0.5 to 71.8 g/L but chloride was always the dominant anion. There is a significant positive relationship between ostracode and water δ18O except at high TDS (>20 g/L) when shell δ18O values are lower than expected. No effect of either temperature or water Mg/Ca is observed on the Mg/Ca in the ostracode calcite in waters with Mg/Ca < 6 (molar ratio). Ostracode shell Sr/Ca is strongly and significantly related to water Sr/Ca. δ13C values in C. torosa shells are ˜2‰ lower than observed δ13CDIC. These results provide new and more accurate quantification tools to reconstruct past hydrochemistry from C. torosa shells.

  15. Southern Polar Front macroecological and biogeographical insights gained from benthic Ostracoda

    NASA Astrophysics Data System (ADS)

    Brandão, Simone N.; Vital, Helenice; Brandt, Angelika

    2014-10-01

    The Southern Ocean is one of the least known marine ecosystems on Earth, but the importance of understanding its biological and geochemical characteristics are urgent, because of the fast changing climate. Primary productivity is a key factor in ecosystem functioning, since this is the only process (except for the rare chemosynthesis) transforming solar energy into organic material, which can later be processed by all other living beings. Herein we investigate how primary productivity in the euphotic zone influences the biodiversity on the sea bed at abyssal depths, using Ostracoda (Crustacea) as a model. We also discuss the biogeographical pattern of the ostracod fauna. Samples collected from the Atlantic sector of the Southern Ocean close to the Southern Polar Front (i.e. ~51°S) during the SYSTCO II expedition are the basis for our analyses. For the statistical tests, we used samples collected with an epibenthic sledge, which has the advantages of sampling a far larger area than traditional gears (i.e. grabs and corers), and also collect Myodocopida and Halocyprida rarely recorded in ostracod studies. However, because of its large mesh size (i.e. 300 and 500 μm) the epibenthic sledge fails to recover small sized ostracods. Most benthic and benthopelagic ostracod species inhabiting the Southern Polar Front region are either endemic to the Southern Ocean or occur close to it. We conclude that ostracod assemblages living below areas of high primary productivity seem to be different to those below low productivity zones, but that assemblages living west of the Mid-Atlantic Ridge are not significantly distinct from the ones living to the east of this putative barrier.

  16. Holocene Ostracoda from the Herald Canyon, Eastern Siberian Sea from the SWERUS-C3 Expedition 2014

    NASA Astrophysics Data System (ADS)

    Gemery, L.; Cronin, T. M.; Jakobsson, M.; Barrientos, N.; O'Regan, M.; Muschitiello, F.; Koshurnikov, A.; Gukov, A.

    2015-12-01

    We analyzed Arctic benthic ostracode assemblages from two piston cores (PC) and their complementary multicores from Herald Canyon in the Eastern Siberian Sea. The cores (SWERUS-L2-2-PC1 [8.1 m], 2-MUC4, 71.7 m water depth, and SWERUS-L2-4-PC1 [6.2 m], 4-MUC4, 119.7 m water depth) were collected during Leg 2 of the 2014 SWERUS-C3 Expedition. Radiocarbon dates on mollusks indicate that sediments from 2-PC1 and 4-PC1 were deposited over the last 5,000 and 10,000 years respectively. The dominant ostracode species include: Acanthocythereis dunelmensis, Cytheropteron elaeni, Elofsonella concinna, Kotoracythere janae, Normanicythere leioderma, Semicytherura complanata. Based on species' distributions obtained from a 1,200-sample modern ostracode database, these species are known to be typical of shallow mid- to outer-continental shelf environments in the modern Arctic Ocean. The abundant and diverse benthic ostracode assemblages found in these cores suggest the influence of nutrient-rich Pacific water flowing in through the Bering Strait. The faunal assemblages are fairly uniform throughout 2-PC1, suggesting minimal variability in Pacific water inflow since at least 5 ka. In the lower section of 4-PC1, there is a major change to ostracode assemblages containing typical inner shelf, often brackish-water species, such as Cytheromorpha macchesneyi, and associated shallow Arctic shelf species (Sarsicytheridea punctillata and several Cytheropteron species), reflecting a period of lower, deglacial sea level.

  17. Paleoclimatic record of the late Quaternary from a gravity core sediment of Lake Hovsgol in northern Mongolia

    NASA Astrophysics Data System (ADS)

    Cheong, D.; Kim, B.

    2007-12-01

    Gravity core sediment (HS 7) from Lake Hovsgol(Mongolia) is divided into three sedimentary units on the basis of sediments texture, water contents, occurrence of fossils and sediment color. Unit 1(27¢¦128§¯) is generally massive and is crudely stratified. Ostracods are well preserved over the all interval of Unit1, but diatoms are not well preserved. At Unit2(9¢¦27§¯), mud content is slightly low and lamination is well developed. It is dark greenish gray in the upper part, and dark greenish gray is alternating with light brownish gray in the lower part. Diatom contents increase towards the top and ostracods fragments disappear at the top of Unit 2. Unit3(0¢¦9§¯) is laminated mud in olive gray color. Diatom contents are high but ostracods are not observed in this unit. According to 14C age dating results, we assumed that Unit1 is Pleistocene sediment, Unit2 is sediment of a transitional stage and Unit 3 is Holocene sediment. Chemical composition of trace elements from ostracods show variations through Unit1, especially showing a distinct change at 95¢¦100§¯ interval. It matches to the distribution of ostracod at this interval. Contents of ostracod decrease at the interval and contents of Cytherissa lacustris decrease, but Limnocythere inopinata increase. It was interpreted that warm air was supplied to Lake Hovsgol after LGM(Last Glacial Maximum), causing ice melting. Consequently the bottom environment of Lake Hovsgol experienced some changes as the lake level increased little bit. At the top of Unit 1 appear a lots of pyrite which are arranged in line, and diatoms occure but ostracods are not observed toward the top of Unit 2, and lamination is developed in Unit 2. It means the bottom environment of Lake Hovsgol changed to anoxic condition. At that time, plenty of water was supplied into the lake, resulting in water stratification and cutting off oxygen supply to the bottom of Lake Hovsgol. It made the lake level rise higher, so that the bottom

  18. Potential of Lake Ohrid for long palaeoclimatic and palaeoenvironemental records: The last glacial-interglacial cycle (140 ka)

    NASA Astrophysics Data System (ADS)

    Belmecheri, S.; von Grafenstein, U.; Namiotko, T.; Robert, C. M.; Andersen, N.; Danielopol, D. L.; Caron, B.; Bordon, A.; Regnier, D.; Mazaud, A.; Sulpizio, R.; Zanchetta, G.; Grenier, C.; Tiercelin, J.; Fouache, E.; Lézine, A.

    2009-12-01

    Lake Ohrid (Albania, Macedonia) is probably the oldest and one of the deepest lakes in Europe. It potentially provides a continuous palaeoenvironmental record over the entire Quaternary. In 2004, a 10-m-long sediment record (JO2004-1) was recovered from the south-western part of the lake from a depth of 100 m (40°55.000 N, 20°40.297 E). The record is a composite of two series of consecutive 3-m-long sections taken from two sites within 5 m lateral distance using a modified Streif-Livingston piston corer (UWITEC, Austria). On the basis of seven AMS radiocarbon dating, five tephras layers and derived accumulation rate model, the Ohrid sequence extends back to 140 ka. It covers the last glacial-interglacial cycle with nearly continuous sedimentation (0.075 mm/yr, on average), except for a major hiatus (at 532.4 cm) of roughly 12,000 years between 102.75 and 89.90 ka. We evaluate the potential of using the oxygen and carbon isotope signature of the calcite of the benthic ostracod valves deposited in Lake Ohrid sediments as a palaeoclimate proxy. Twelve ostracod species, which are all endemic to Lake Ohrid, were preserved only during the interglacial phases. Their absence during full glacial periods is most likely due to calcium carbonate under-saturation of the lake water, when permafrost prohibited infiltration of atmospheric water into the limestone complexes in the lake drainage basin. For periods with ostracod preservation, the oxygen isotope signature of ostracod calcite is a reliable measure of the oxygen isotope composition of past lake water. However, the climatic interpretation of this record is strongly biased by water balance variations and by varying contribution of different vapour sources. The carbon isotope record of ostracods responds more consistently to climatic changes, and is a potentially quantifiable proxy for vegetation cover and soil build-up. Ostracod preservation and oxygen and carbon isotopes both record a succession of glacial

  19. The relationship between extrinsic and intrinsic events in the evolution of Mesozoic non-marine Ostracoda

    NASA Astrophysics Data System (ADS)

    Whatley, Robin

    The Cypridacea first entered non-marine environments in a sustained invasion in the Upper Bathonian. They were, until the late Tithonian, subordinate to the only other Mesozoic non-marine ostracods, the Darwinulacea and the Limnocytheridae. In the late Tithonian and Neocomian, however, they became pandemic in their distribution and totally dominated the other two groups. The great rapidity of their dispersal is attributed to their having evolved, late in the Jurassic, the ability to reproduce parthenogenetically and to lay desiccation and freezing resistant eggs. The great increase in their diversity at the Jurassic-Cretaceous boundary is thought in part to be due to their ability to swim, a facility denied their competitors. It is suggested that the late Jurassic non-marine Cypridacea constitute an excellent example of Hopeful Monsters. The possible passive dispersal of ostracods by Mesozoic vertebrates is discussed.

  20. Selective silicification of fossils by syntaxial overgrowths on quartz sand, Oriskany Sandstone (Lower Devonian), New York

    NASA Astrophysics Data System (ADS)

    Maliva, Robert G.

    1992-07-01

    Some fossil fragments in the Oriskany Sandstone (Lower Devonian) of New York were partially replaced by syntaxial quartz overgrowths. These replacive overgrowths are significant in that they provide insights into the mechanism and controls of quartz replacement of calcite. The susceptibility of the different calcite types of quartz replacement was governed by their microstructural complexity. Fossil fragments with finely crystalline microstructures, such as brachiopods, ostracods, and bryozoans, were partially replaced by quartz, whereas echinoderm ossicles, which consist of single large calcite crystals, were not replaced. Calcite cement was also immune to replacement. Brachiopod, bryozoan, and ostracod bioclasts (with minor exceptions) underwent partial replacement by quartz (with its concomitant shell calcite dissolution) only where the shell fragments were in contact with detrital quartz grains. Proximity to authigenic crystal nucleation sites (i.e., quartz sand grains) was thus the prime control over whether host mineral dissolution occurred, which is a situation unique to the force of crystallization-driven replacement mechanism.

  1. Tracing the evolution of oblitacythereis through a sudden event of oceanic proportions

    SciTech Connect

    Benson, R.H.

    1985-01-01

    The ostracod genus Oblitacythereis is characteristic of the upper bathyal sediments of Neogene age in the region of the Mediterranean, just outside of the Straits of Gibraltar in the Atlantic and on the Walvis Ridge. Its evolution can be traced from a Tethyan ancestry of its carapace sculpture through 1) changes in structurally-important cell division in the histological pattern forming the reticulation of the carapace, and 2) modification of positions in the pore conuli of the epidermal nervous system. This study examines the changes that take place near Gibraltar at the time of the formation of the Mediterranean after the Messinian Salinity Crisis and compares these changes with other similar histories of deeper - and shallower - water ostracod genera.

  2. The effect of long-term spatiotemporal variations in urbanization-induced eutrophication on a benthic ecosystem, Osaka Bay, Japan

    USGS Publications Warehouse

    Yasuhara, Moriaki; Yamazaki, Hideo; Tsujimoto, Akira; Hirose, K.

    2007-01-01

    Detailed spatiotemporal patterns of the influence of urbanization-induced eutrophication on a metazoan benthic community in Osaka Bay were determined using sediment cores and fossil ostracode assemblages from the last 200 yr. Results suggest that total abundance of ostracodes increased in the middle part of the bay as a result of the increase of food supply by eutrophication. Conversely, abundance decreased in the inner bay, likely because of bottom-water hypoxia by eutrophication. The variation in species composition among sites within the bay may have decreased because of the effect of eutrophication, i.e., the dominance of species that prefer food-rich environments throughout all sites. These eutrophication-induced changes occurred around 1900 as a result of Japan's industrial revolution and around 1960 as a result of rapid urbanization, depending upon location. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

  3. The uplift of the central High Atlas as deduced from neogene continental sediments of the Ouarzazate province, Morocco

    NASA Astrophysics Data System (ADS)

    Görler, Konrad; Helmdach, Friedrich-Franz; Gaemers, Pieter; Heißig, Kurt; Hinsch, Winfried; Mädler, Karl; Schwarzhans, Werner; Zucht, Monika

    South of the central High Atlas, continental Neogene sediments crop out in the following areas: in a palaeo-drainage system in the Anti-Atlas, in a southern foredeep of the central High Atlas (Ouarzazate basin), and in the intensively folded South Atlas Marginal Zone. The latter two are characterized at the base and the top of the Neogene by thick alluvial-fan sequences and gravitational-glide slabs. They are correlated to episodes of rapid uplift of the axial zone of the High Atlas during Oligocene/Early Miocene and Late Pliocene/Early Pleistocene time. The intermediate sedimentation comprises widespread lake deposits. Charophytes, mollusks, ostracodes, fishes and small mammals from the lacustrine sediments have been studied and their biostratigraphic position (Mellalian/Vallesian to Late Pliocene) has been established. Lithology and the faunas of ostracodes and fishes demonstrate a frequent change of salinity during the lacustrine sedimentation.

  4. Late Neogene marine Ostracoda from Tjornes, Iceland

    USGS Publications Warehouse

    Cronin, T. M.

    1991-01-01

    On the western side of the Tjornes Peninsula in northern Iceland exposures of fossiliferous marine sediments, basalts, and glacial tills record the climatic history of this region of the North Atlantic Ocean. Seventy-five marine ostracode species were recovered from the Pliocene Tjornes sediments and Quaternary sediments known as the Breidavik beds. New species Bensonocythere eirikssoni, Robertsonites williamsi, Hemicythere rekaensis, Thaerocythere mayburyae, Thaerocythere whatleyi, Leptocythere tjornesensis, Tetracytherura bardarsoni, and Cytheromorpha einarssoni are described. -from Author

  5. Correspondence of terrestrial and marine paleoclimates, SW Florida, during Mid-Pliocene periods of global warmth

    SciTech Connect

    Willard, D.A.; Cronin, T.M.; Litwin, R.J. National Center)

    1992-01-01

    Pollen and ostracode samples from shallow-marine strata of the Pinecrest Beds near Sarasota, FL were studied to compare terrestrial and marine paleoclimate records during periods of middle Pliocene global warmth. Pollen assemblages from strata deposited during sea-level highstands from about 3.5--3.0 Ma are dominated by Pinus pollen with subdominant Ouercus and common taxodiaceous pollen, which increases markedly in abundance near about 3.0 Ma. Comparison with modern, shallow-marine pollen assemblages from the east coast of the United States indicates that the 3.5--3.0 Ma vegetation was, overall, similar to vegetation from the southern third Florida. However, near 3.0 Ma, pollen assemblages become less similar to modern assemblages due to higher percentages of taxodiaceous pollen and lower percentages of herbaceous pollen. Such changes are consistent with warmer climates and, possibly, moister soil conditions. Marine ostracodes also show progressively higher percentages of thermophilic (subtropical/tropical) taxa and decreasing percentages of cryophilic (temperature) taxa between 3.5--3.0 Ma. From about 2.5--2.0 Ma, ostracode assemblages recorded open-bay, sometimes brackish environments similar to those in subtropical eastern North America today. The Pinecrest paleoclimate record shows (1) that during two periods of global warmth and high sea level, subtropical terrestrial and marine climates were not substantially warmer than today; (2) ocean and atmosphere temperatures probably were about the same as today, perhaps slightly higher during peak warmth near 3.0 Ma; (3) changes in pollen assemblages appear to lag behind changes in ostracode assemblages; (4) progressively warmer local climates 3.5--3.0 Ma probably record an increasing influence of warm Gulf Stream water as the Central American Isthmus closed.

  6. The Miocene Cyprideis species flock (Ostracoda; Crustacea) of western Amazonia (Solimões Formation)

    NASA Astrophysics Data System (ADS)

    Gross, Martin; Ramos, Maria Ines F.; Piller, Werner E.

    2015-04-01

    The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic aquatic invertebrate fauna (e.g., molluscs, ostracods). Among ostracods, the genus Cyprideis experienced a remarkable radiation. Micropalaeontologic investigations of a 400-m-long sediment core (~62 km SW Benjamin Constant, Amazonia, Brazil) permitted a taxonomic revision of about two-thirds of hitherto described Cyprideis species. Ostracod index species enabled a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to Cyprideis cyrtoma biozones (late middle to early late Miocene age). The current study underlines once more Cyprideis' remarkable capability to produce species flocks and western Amazonian Cyprideis comply with the criteria of a species flock: i) endemicity: up to now not a single species is recorded in adjacent areas; ii) monophyly: although hardly verifiable to date and probably Amazonian Cyprideis is not monophyletic s.str., several closely related, quite rapidly evolving species are proved; iii) speciosity: due to the present study, 30 formally described species exist; several further species, left in open nomenclature, are recorded in the literature, which strongly hints to a much higher, still unrecorded species richness; iv) ecological diversity: based on rare sedimentologic cross-references, ecological diversity within a highly structured wetland is possible; the current results demonstrate the sympatric occurrence of up to 12 Cyprideis species, which may indicate adaptations to different microhabitats; v) habitat dominance: regularly Cyprideis holds more than >90 % in western Amazonian ostracod assemblages during the early and middle Miocene. Explanations for this extreme habitat monopolisation are still arguable and touch the highly disputed question about the nature of western Amazonia's environments during the Miocene. It seems, however, evident that a strictly actualistic approach to endemic Neogene Amazonian biota is highly

  7. Divergent Palate Morphology in Turtles and Birds Correlates With Differences in Proliferation and BMP2 Expression During Embryonic Development

    PubMed Central

    ABRAMYAN, JOHN; JIA-MIEN LEUNG, KELVIN; RICHMAN, JOY MARION

    2014-01-01

    During embryonic development, amniotes typically form outgrowths from the medial sides of the maxillary prominences called palatal shelves or palatine processes. In mammals the shelves fuse in the midline and form a bony hard palate that completely separates the nasal and oral cavities. In birds and lizards, palatine processes develop but remain unfused, leaving a natural cleft. Adult turtles do not possess palatine processes and unlike other amniotes, the internal nares open into the oral cavity. Here we investigate craniofacial ontogeny in the turtle, Emydura subglobosa to determine whether vestigial palatine processes develop and subsequently regress, or whether development fails entirely. We found that the primary palate in turtles develops similarly to other amniotes, but secondary palate ontogeny diverges. Using histology, cellular dynamics and in situ hybridization we found no evidence of palatine process development at any time during ontogeny of the face in the turtle. Furthermore, detailed comparisons with chicken embryos (the model organism most closely related to turtles from a molecular phylogeny perspective), we identified differences in proliferation and gene expression patterns that correlate with the differences in palate morphology. We propose that, in turtles, palatine process outgrowth is never initiated due to a lack of mesenchymal bone morphogenetic protein 2 (BMP2) expression in the maxillary mesenchyme, which in turn fails to induce the relatively higher cellular proliferation required for medial tissue outgrowth. It is likely that these differences between turtles and birds arose after the divergence of the lineage leading to modern turtles. PMID:24323766

  8. Living benthic foraminiferal species as indicators of cold-warm water masses interaction and upwelling areas

    NASA Astrophysics Data System (ADS)

    Eichler, Patrícia P. B.; Pimenta, Felipe M.; Eichler, Beatriz B.; Vital, Helenice

    2016-03-01

    The western South Atlantic continental margin, between 27° and 37°S, is dominated by four main water masses: cold-fresh Subantarctic Shelf Water (SASW), warm-salty Subtropical Shelf Water (STSW), cold upwelled South Atlantic Central Water (SACW), and fresh Plata Plume Water (PPW). Despite the large seasonal variability of PPW extension along the shelf, an intense and relatively stable temperature-salinity gradient separates the SASW and the STSW forming the Subtropical Shelf Front (STSF) around 32°S. The two dominant shelf water masses (SASW and STSW) arise from the process of mixing of oceanic waters. The SASW originates from the dilution of Subantarctic Water due to excess precipitation and continental runoff, and the STSW consists of modified warm tropical waters and South Atlantic Central Water (SACW) diluted below PPW. A previous article demonstrates distribution of Bulimina marginata, a shelf environment and deep-sea species of benthic foraminifera, is influenced by the front location and it can be used as a proxy of the STSF in sediment core analysis. Here we show three other infaunal living species inhabiting at the Continental margin: Buccella peruviana, Globocassidulina subglobosa and Uvigerina peregrina and their distribution limits show the interaction of Subantartic Shelf Water, Subtropical Shelf Water, and upwelling of SACW, in the bottom sediment of coastal studied areas.

  9. A benthic foraminiferal record of middle to late Pliocene (3.15-2.85 Ma) deep water change in the North Atlantic

    USGS Publications Warehouse

    Ishman, S.E.

    1996-01-01

    Records of benthic foraminifera from North Atlantic DSDP Site 607 and Hole 610A indicate changes in deep water conditions through the middle to late Pliocene (3.15 to 2.85 Ma). Quantitative analyses of modern associations in the North Atlantic indicate that seven species, Fontbotia wuellerstorfi, Cibicidoides kullenbergi, Uvigerina peregrina, Nuttallides umboniferus, Melonis pompilioides, Globocassidulina subglobosa and Epistominella exigua are useful for paleoenvironmental interpretation. The western North Atlantic basin (Site 607) was occupied by North Atlantic Deep Water (NADW) until ???2.88 Ma. At that time, N. umboniferus increased, indicating an influx of Southern Ocean Water (SOW). The eastern North Atlantic basin (Hole 610A) was occupied by a relatively warm water mass, possibly Northeastern Atlantic Deep Water (NEADW), through ???2.94 Ma when SOW more strongly influenced the site. These interpretations are consistent with benthic ??18O and ??13C records from 607 and 610A (Raymo et al., 1992). The results presented in this paper suggest that the North Atlantic was strongly influenced by northern component deep water circulation until 2.90-2.95 Ma. After that there was a transition toward a glacially driven North Atlantic circulation more strongly influenced by SOW associated with the onset of Northern Hemisphere glaciation. The circulation change follows the last significant SST and atmospheric warming prior to ???2.6 Ma.

  10. Variability of South Atlantic Central Water in the last century based on stable isotopes and benthic foraminifera of southeast Brazilian continental shelf.

    NASA Astrophysics Data System (ADS)

    Barbosa, C. F.; De Faria, G. R.; Albuquerque, A. L.

    2014-12-01

    In order to better understand the changes in productivity and water masses that permeate the bottom of the continental shelf of southeast Brazilian margin influenced by upwelling, three box-cores were collected in a bathymetric transect. Cores were analyzed for assemblage composition of benthic foraminifera and isotopes. 55 samples were analyzed and 227 benthic foraminifera were identified, but only 18 of them showed relative frequencies that contributed to the understanding of both oceanographic dynamics and productivity conditions of the area. There was dominance of Globocassidulina subglobosa, which is considered an indicator of areas with pulses of phytodetritus. Statistical analysis separated samples into different groups according to their location, indicating environmental factors on the continental shelf. Innershore core showed the highest flux of benthic foraminifera and the offshore one showed the major diversity and variation of foraminifera assemblages over time. Mid shelf cores showed little variation of the assemblages and indicate a stable environment. The δ13C values of Uvigerina peregrina indicated more degraded organic matter in the center of the shelf. The mean composition of Cibicides spp. δ13C is, on average, 0.25 ‰ depleted related to the values of δ13CDIC. Such values associated with high frequency of phytodetritus species indicated the formation of a phytodetritus layer at the bottom of the continental shelf of Cabo Frio. The paleotemperature calculated from oxygen isotopes pointed the permanence of SACW at the shelf bottom over the last few centuries.

  11. Pelvic girdle mobility of cryptodire and pleurodire turtles during walking and swimming.

    PubMed

    Mayerl, Christopher J; Brainerd, Elizabeth L; Blob, Richard W

    2016-09-01

    Movements of the pelvic girdle facilitate terrestrial locomotor performance in a wide range of vertebrates by increasing hind limb excursion and stride length. The extent to which pelvic movements contribute to limb excursion in turtles is unclear because the bony shell surrounding the body presents a major obstacle to their visualization. In the Cryptodira, which are one of the two major lineages of turtles, pelvic anatomy indicates the potential for rotation inside the shell. However, in the Pleurodira, the other major suborder, the pelvis shows a derived fusion to the shell, preventing pelvic motion. In addition, most turtles use their hind limbs for propulsion during swimming as well as walking, and the different locomotor demands between water and land could lead to differences in the contributions of pelvic rotation to limb excursion in each habitat. To test these possibilities, we used X-ray reconstruction of moving morphology (XROMM) to compare pelvic mobility and femoral motion during walking and swimming between representative species of cryptodire (Pseudemys concinna) and pleurodire (Emydura subglobosa) turtles. We found that the pelvis yawed substantially in cryptodires during walking and, to a lesser extent, during swimming. These movements contributed to greater femoral protraction during both walking and swimming in cryptodires when compared with pleurodires. Although factors related to the origin of pelvic-shell fusion in pleurodires are debated, its implications for their locomotor function may contribute to the restriction of this group to primarily aquatic habits. PMID:27340204

  12. Holocene oceanographic and climatic variability of the Vega Drift deduced through foraminiferal interpretation

    USGS Publications Warehouse

    Szymcek, Phillip; Ishman, Scott E.; Domack, Eugene W.; Leventer, Amy

    2007-01-01

    fusiformis assemblages. Most agglutinated forms tend to decrease downcore, and comparisons to modern analogues imply post-depositional disintegration, while calcareous taxa indicate non-corrosive bottom waters. The lower to middle Holocene Vega Drift sediments are characterized by the calcareous S. fusiformis assemblage and glacial plume sediments. This assemblage is characterized by calcareous forms including Globocassidulina biora, G. subglobosa, and Nonionella iridea. The planktic species Neogloboquadrina pachyderma is associated with the S. fusiformis assemblage. The S. fusiformis assemblage is faunally similar to assemblages described in fjords of the western Antarctic Peninsula and indicates non-corrosive bottom water. Sediments of the mid to upper Holocene interval are characterized by the T. wiesneri and M. arenacea assemblages and indicate the presence of Hyper Saline Shelf Water. These assemblages are similar to modern assemblages directly to the south in the Prince Gustav Channel. The upper Holocene is marked by several small intervals with taxonomic characteristics similar to the S. fusiformis assemblage, indicating periodic introduction of non-corrosive bottom water to the Vega Drift

  13. Foraminiferal biodiversity associated with cold-water coral carbonate mounds and open slope of SE Rockall Bank (Irish continental margin—NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Morigi, C.; Sabbatini, A.; Vitale, G.; Pancotti, I.; Gooday, A. J.; Duineveld, G. C. A.; De Stigter, H. C.; Danovaro, R.; Negri, A.

    2012-01-01

    Cold-water coral (CWC) ecosystems are hotspots of macro- and microfaunal biodiversity and provide refuge for a wide variety of deep-sea species. We investigated how the abundance and biodiversity of 'live' (Rose Bengal stained) foraminifera varies with, and is related to, the occurrence of CWC on the Rockall Bank (NE Atlantic). Qualitative and quantitative analyses were performed on 21 replicate samples from 8 deep-sea stations, including 4 stations on CWC-covered carbonate mounds at depths of 567-657 m, and 4 stations on the adjacent slope at depths of 469-1958 m where CWC were absent. This sampling strategy enabled us to demonstrate that sediments surrounding the living CWC were characterised by higher foraminiferal abundance and biodiversity than open-slope sediments from the same area. A total of 163 foraminiferal species was identified. The dominant species in CWC sediments were: Spirillina vivipara, Allogromiid sp. 1, Globocassidulina subglobosa, Adercotryma wrighti, Eponides pusillus, Ehrenbergina carinata, Planulina ariminensis, Trochammina inflata and Paratrochammina challengeri. Foraminifera were nearly absent in adjacent open slope areas subject to strong tidal currents and characterised by coarse grained deposits. We suggest that CWC create a heterogeneous three-dimensional substrate offering microhabitats to a diverse benthic foraminiferal community.

  14. Databases and Geographical Information Systems at the research/teaching interface: palaeoclimate proxies, freshwater biodiversity and the OMEGA project

    NASA Astrophysics Data System (ADS)

    Horne, David

    2013-04-01

    The Mutual Ostracod Temperature Range (MOTR) method provides Quaternary palaeotemperature range estimates based on fossil ostracod assemblages calibrated using modern distributional databases and climate data. Over the past five years, aspects of the development and application of the MOTR method have been incorporated into undergraduate teaching in two second-year modules (Global Environmental Change and Digital Worlds: Cartography, Geographical Information Systems and Modelling) via lectures and practical exercises. Consequently, several students became sufficiently interested and enthused to undertake successful major projects aimed at developing, testing and applying aspects of the method, leading in turn to postgraduate work on the same topic in two cases and in a third case to co-authorship of a research publication. Thus both research and teaching have benefited from the integration of an innovative geoscience application with undergraduate coursework. The scope of MOTR applications is being expanded from European to global via the Ostracod Metadatabase of Environmental and Geographical Attributes (OMEGA) project; the current focus is on harmonising North American and European datasets, supported by the EU-funded (FP7) BioFresh project which is building a global information platform with access to all available databases of freshwater biodiversity. Undergraduate participation will be sought to underpin a Citizen Science initiative aimed at checking, correcting and validating the geographic referencing of species' records in the databases, using datasets exported as Keyhole Markup Language files for use in Google Earth.

  15. Neogene biostratigraphy and paleoenvironments of Enewetak Atoll, equatorial Pacific Ocean

    USGS Publications Warehouse

    Cronin, T. M.; Bybell, L.M.; Brouwers, E.M.; Gibson, T.G.; Margerum, R.; Poore, R.Z.

    1991-01-01

    Micropaleontologic analyses of Neogene sediments from Enewetak Atoll, Marshall Islands, provide data on the age of lagoonal deposits, stratigraphic disconformities and the paleoenvironmental and subsidence history of the atoll. Benthic foraminifers, planktic foraminifers, calcareous nannofossils and ostracodes were studied from six boreholes, the deepest penetrating 1605 feet below the lagoon floor into upper Oligocene strata. The Oligocene-Miocene boundary occurs at about 1200 ft below the lagoon floor. The early and middle Miocene is characterized by brief periods of deposition and numerous hiatuses. Ostracodes and benthic foraminifers indicate a shallow-marine reefal environment with occasional brackish water conditions. Upper Miocene and lower Pliocene deposits placed in calcareous nannofossil Zones NN9-15 and in planktic foraminifer Zones N16-19 contain species-rich benthic microfaunas which indicate alternating reefal and brackish water mangrove environments. The upper Pliocene contains at least two major depositional hiatuses that coincide with a major faunal turnover in benthic foraminiferal and ostracode assemblages. The Quaternary is characterized by benthic microfaunas similar to those of modern atoll lagoons and is punctuated by at least 11 disconformities which signify periods of low sea level. Atoll subsidence rates during the last 10 Ma averaged 30 to 40 m/m.y. ?? 1991 Elsevier Science Publishers B.V. All rights reserved.

  16. North atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles

    USGS Publications Warehouse

    Dwyer, G.S.; Cronin, T. M.; Baker, P.A.; Raymo, M.E.; Buzas, Jeffrey S.; Correge, T.

    1995-01-01

    Variations in the ratio of magnesium to calcium (Mg/Ca) in fossil ostracodes from Deep Sea Drilling Project Site 607 in the deep North Atlantic show that the change in bottom water temperature during late Pliocene 41,000-year obliquity cycles averaged 1.5??C between 3.2 and 2.8 million years ago (Ma) and increased to 2.3??C between 2.8 and 2.3 Ma, coincidentally with the intensification of Northern Hemisphere glaciation. During the last two 100,000-year glacial-to-interglacial climatic cycles of the Quaternary, bottom water temperatures changed by 4.5??C. These results show that glacial deepwater cooling has intensified since 3.2 Ma, most likely as the result of progressively diminished deep-water production in the North Atlantic and of the greater influence of Antarctic bottom water in the North Atlantic during glacial periods. The ostracode Mg/Ca data also allow the direct determination of the temperature component of the benthic foraminiferal oxygen isotope record from Site 607, as well as derivation of a hypothetical sea-level curve for the late Pliocene and late Quaternary. The effects of dissolution on the Mg/Ca ratios of ostracode shells appear to have been minimal.

  17. Timing of atmospheric precipitation in the Zagros Mountains inferred from a multi-proxy record from Lake Mirabad, Iran

    NASA Astrophysics Data System (ADS)

    Stevens, Lora R.; Ito, Emi; Schwalb, Antje; Wright, Herbert E.

    2006-11-01

    A sediment core 7.2 m long from Lake Mirabad, Iran, was examined for loss-on-ignition, mineralogy, oxygen-isotopic composition of authigenic calcite, and trace-element composition of ostracodes to complement earlier pollen and ostracode-assemblage studies. Pollen, ostracode-inferred lake level, and high Sr/Ca ratios indicate that the early Holocene (10000 to 6500 cal yr BP) was drier than the late Holocene. Low δ18O values during this interval are interpreted as resulting from winter-dominated precipitation, characteristic of a Mediterranean climate. Increasing δ18O values after 6500 cal yr BP signal a gradual increase in spring rains, which are present today. A severe 600-yr drought occurred at ca. 5500 cal yr BP, shortly after the transition from pistachio-almond to oak forest. During the late Holocene, two milder droughts occurred at about 1500 and 500 cal yr BP. Within the resolution of the record, no drought is evident during the collapse of the Akkadian empire (4200-3900 cal yr BP). Rather, a decrease in δ18O values to early-Holocene levels may indicate the return to a Mediterranean precipitation regime.

  18. Macrofossils of Bakken Formation (Devonian and Mississippian), Williston Basin, North Dakota

    SciTech Connect

    Thrasher, L.; Holland, F.D. Jr.

    1983-08-01

    Results of this study of the macrofossils of the Bakken Formation in North Dakota have reinforced the suggestion, based on previous paleontological work in Saskatchewan, that the Bakken is of both Devonian and Mississippian age, rather than being entirely of Lower Mississippian age as originally considered. Increased drilling and coring activity in the North Dakota part of the Williston Basin has provided the opportunity for acquiring a larger fauna that was previously available. Based on lithologic character, the Bakken has been divided into three informal members. These consist of a calcareous siltstone unit between two lithologically similar units of carbonaceous shale. These black shales contain similar faunas distinct from that of the middle member. The black shales contain inarticulate brachiopods, conchostracans, and rare cephalopods and fish remains as well as more abundant conodonts, ostracods, and palynomorphs. The middle siltstone unit contains a more abundant and diverse fauna consisting of inarticulate and articulate brachiopods together with corals, gastropods, cephalopods, ostracods, echinoderm remains, and trace fossils. This is the first report of cephalopods, conchostracans, ostracods, corals, trace fossils, and some of the brachiopods in the Bakken, although all, except the gastropods, have been reported from stratigraphic equivalents (Exshaw Formation of south-central Montana, the Leatham Formation of northeastern Utah, and the middle member of the Pilot Shale in western Utah and eastern Nevada).

  19. Discovery of silicified lacustrine micro-fossils and stromatolites: Triassic-Jurassic Fundy Group, Nova Scotia

    SciTech Connect

    Cameron, B.

    1985-01-01

    A unique assemblage of silicified invertebrate and algal fresh-water lake fossils has been discovered in the Scots Bay Formation at the top of the Triassic-Jurassic Fundy Group of the Fundy Basin in Nova Scotia. This is important because the basins of the eastern North American Triassic-Jurassic rift system have not yielded many invertebrate and algal fossils. These new finds will contribute significantly to evolutionary, paleoecological and biostratigraphic studies of fresh-water Mesozoic deposits. Silicified fossils have been extracted from chert-bearing, mixed carbonate and siliciclastic lithologies. They include ostracodes, gastropods, rare bivalves, charaphytes (algae), stromatolites, and chert nodules cored with well-preserved woody tissues of tree trunks. Possible algal filaments occur in the silicified stromatolites. This association of charaphytes, ostracodes, microscopic gastropods and stromatolites is found in carbonate lakes today. The Scots Bay Formation is probably a near-shore carbonate facies of the more widespread silicilastic lacustrine McCoy Brook Formation. The gastropods and ostracodes, studied by SEM, indicate a Jurassic age for the Scots bay Formation, confirming speculations based on other data.

  20. Microfossils from Cerro Prieto geothermal wells, Baja California, Mexico

    SciTech Connect

    Cotton, M.L.; Vonder Haar, S.

    1980-01-01

    To aid in a paleoenvironmental and age reconstruction of the Cerro Prieto reservoir system, 59 samples of well cuttings were analyzed for microfossils. The cuttings were obtained at depths from 351 to 3495 m in 14 geothermal wells in the Cerro Prieto field, Baja California, Mexico. We found foraminifera in 6 samples, ostracodes in 19 samples, and nannoplankton as coccoliths in 24 samples. Other groups, such as molluscs, insects, fish skeletal parts, and plant material were occasionally present. Detailed interpretations are not possible at this time because of poor preservation of samples. This is primarily due to causes: dissolution by geothermal fluids that reach 350{sup 0}C, and the extensive mixing of filled Cretaceous forms (reworked from the Colorado Plateau region) with Tertiary species during drilling. Further studies of ostracodes and foraminifera from colder portions of the wells are needed. The abundant and well-preserved ostracodes indicate marine to brackish water environments that correspond, in part, to lagoonal or estuarine facies. The presence of the mid-Tertiary (15-My-old) marine foraminifera, Cassigerinela chipolensis, in wells M-11 and M-38, 350 to 500 m deep, is perplexing. These are not laboratory contaminates and, as yet, have not been found in the drilling mud. If further studies confirm their presence at Cerro Prieto, established ideas about the opening of the Gulf of California and about Pacific Coast mid-Tertiary history will need to be rewritten.

  1. A paleoecologic reconstruction of the history of Featherbed Bank, Biscayne National Park, Biscayne Bay, Florida

    USGS Publications Warehouse

    Stone, Jeffery R.; Cronin, T. M.; Brewster-Wingard, G. L.; Ishman, S.E.; Wardlaw, B.R.; Holmes, C.W.

    2000-01-01

    Using multiple-proxy biological indicators, a paleoecological history of the past 550 years of Featherbed Bank, Biscayne Bay, has been reconstructed from a short (2.26 m) sediment core. Paleoecological changes in ostracode, mollusc, and foraminifer assemblages show that core SEI297-FB-1 can be divided into three distinctly different zones, which together provide evidence for distinct changes in historical environmental conditions at Featherbed Bank. Assemblages from fossil biotic communities within zone 1, representing approximately 1440 to 1550 AD, are characterized by open-marine biota with relatively limited numbers of epiphytic biota. Molluscan faunal indicators suggest the sediment was capable of supporting infaunal organisms and that faunal richness was relatively limited during this time period. A change in the biotic community occurred around 1550 AD and continued until the late 1800's distinguishing zone 2. Fossil biotic indicators from zone 2 show a strong dominance of epiphytic organisms within all of the biotic communities examined. Foraminifers, molluscs, and ostracodes capable of subsisting in salinities slightly lower than normal marine begin to flourish in this time period, and there is a marked decline in infaunal molluscs. Zone 2 assemblages are replaced around 1900 AD by increased numbers of organisms that typify open-marine conditions and a return to decreased epiphytic assemblages, similar to zone 1. Zone 3 assemblages, however, show some strong dissimilarities from zone 1, including limited infaunal molluscs, increased abundances of the ostracode Malzella floridana, and a significant increase in molluscan faunal richness.

  2. The effects of ultraviolet-B radiation on freshwater invertebrates: Experiments with a solar simulator

    USGS Publications Warehouse

    Hurtubise, R.D.; Havel, J.E.; Little, E.E.

    1998-01-01

    There is concern that decreases in stratospheric ozone will lead to hazardous levels of ultraviolet-B (UV-B) radiation at the Earth's surface. In clear water, UV-B may penetrate to significant depths. The purpose of the current study was to compare the sensitivity of freshwater invertebrates to UV-B. We used a solar simulator, calibrated to match local ambient solar radiation, to expose five species of freshwater invertebrates to enhanced levels of UV-B radiation. UV-B measurements in a eutrophic pond revealed that 10% of the irradiance penetrated to 30-cm depth and 1% to 57-cm depth. The irradiance at the upper 5-20 cm was comparable to levels used in the simulator. Median lethal dose (LD50) values were determined for the cladocerans Ceriodaphnia reticulata, Scapholeberis kingii (two induced color morphs), and Daphnia magna; the ostracod Cyprinotus incongruens; and the amphipod Hyalella azteca. Among the species, 96-h LD50 estimates were quite variable, ranging from 4.2 to 84.0 ??W cm-2. These estimates indicated S. kingii to be highly sensitive and H. azteca, C. reticulata, and D. magna to be moderately sensitive, whereas the ostracod C. incongruens was very tolerant to UV-B radiation. Overall, this study suggests that, in shallow ponds without physical refuges, UV-B radiation would have the strongest effects upon cladocerans and amphipods occurring in the water column, whereas ostracods would be better protected.

  3. Lithostratigraphic description, sedimentological characteristics and depositional environments of rocks penetrated by Illela borehole, Sokoto Basin, NW Nigeria: A connection between Gulf of Guinea Basins

    NASA Astrophysics Data System (ADS)

    Toyin, A.; Adekeye, O. A.; Bale, R. B.; Sanni, Z. J.; Jimoh, O. A.

    2016-09-01

    The basal unit of the succession in the Illela borehole belongs to the Dange Formation comprising thick calcareous and variably coloured dark-greyish shale of 36.30 m thick which is overlain by a 31.44 m thick limestone of Kalambaina Formation with 1.7 m thick shaly-limestone inclusive. The uppermost part of the section belongs to the Gwandu Formation which has intercalation of silty-clay, muddy siltstones with well lithified ironstone capping the borehole section. The limestone/carbonate microfacie as deduced from their salient lithologic, sedimentologic and paleontologic features are comparable to standard microfacie (SMF) types 9 and 10, i.e. bioclastic wackestone/bioclastic micrite and packstone-wackestone respectively. Diagenetically, syndepositional and early diagenesis have taken place particularly cementation and replacement in the carbonate rocks and these have greatly affected the reservoir potential negatively. The matrix/grain relationships indicate a shallow marine environment of deposition. The borehole section is delineated into upper foraminifera and lower ostracod biostratigraphic units as no formal biostratigraphic zonation could be attempted due to low diversity of both benthic foraminifera, marine ostracods and the absence of planktonic foraminifera. The similarity of the ostracod assemblages between this study area, Illela borehole, West Africa, North Africa (Libya), Mali and Niger Republic) and South-Western Nigeria (West Africa) suggests that a marine connection exists between the Gulf of Guinea and the Sokoto Basin via the area occupied by the River Niger during the Paleocene.

  4. Holocene lake salinity changes in the Wimmera, southeastern Australia, provide evidence for millennial-scale climate variability

    NASA Astrophysics Data System (ADS)

    Kemp, Justine; Radke, Lynda C.; Olley, Jon; Juggins, Steve; De Deckker, Patrick

    2012-01-01

    Palaeosalinity records for groundwater-influenced lakes in the southwest Murray Basin were constructed from an ostracod-based, weighted-averaging transfer function, supplemented with evidence from Campylodiscus clypeus (diatom), charophyte oogonia, Coxiella striata (gastropod), Elphidium sp. (foraminifera), Daphniopsis sp. ephippia (Cladocera), and brine shrimp (Parartemia zietziana) faecal pellets, the δ18O of ostracods, and > 130 μm quartz sand counts. The chronology is based on optically stimulated luminescence and calibrated radiocarbon ages. Relatively wet conditions are marked by lower salinities between 9600 yr and 5700 yr ago, but mutually exclusive high- and low-salinity ostracod communities suggest substantial variability in effective precipitation in the early Holocene. A drier climate was firmly in place by 4500 yr and is marked at the groundwater-dominated NW Jacka Lake by an increase in aeolian quartz and, at Jacka Lake, by a switch from surface-water to groundwater dominance. Short-lived, low-salinity events at 8800, 7200, 5900, 4800, 2400, 1300 and 400 yr are similar in timing and number to those recorded on Australia's southern continental shelf, and globally, and provide evidence for the existence of the ~ 1500-yr cycle in mainland southern Australia. We surmise that these are cool events associated with periodic equatorward shifts in the westerly wind circulation.

  5. Microfossils from Cerro Prieto geothermal wells, Baja California, Mexico

    SciTech Connect

    Cotton, M.L.; Haar, S.V.

    1982-08-10

    To aid in a paleonenvironmental and age reconstruction of the Cerro Prieto reservoir system, 59 samples of well cuttings were analyzed for microfossils. The cuttings were obtained at depths from 351 to 3495m in 14 geothermal wells in the Cerro Prieto field, Baja California, Mexico. Foraminifera was found in 6 samples, ostracodes in 19 samples and mannoplankton as coccoliths in 24 samples. Other groups, such as molluscus, insects, fish skeletal parts, and plant material were occasionally present. Detailed interpretations at this time cannot be made because of poor preservation of samples. This is primarily due to causes: dissolution by geothermal fluids that reach 350/sup 0/C, and the extensive mixing of filled Cretaceous forms (reworked from the Colorado Plateau region) with Tertiary species during drilling. Further studies of ostracodes and foraminifera from colder portions of the wells are needed. The abundant and well-preserved ostracodes indicate marine to backish water inviroments that correspond in part, to lagoonal or estuarine facies. The presence of the mid-Tertiary (15-m.y.-old) marine foraminifera, Cassigerinela chipolensis, in wells M-11 and M-38, 350 to 500m deep, is perplexing. These are not laboratory contaminates and, as yet have not been found in the drilling mud. If further studies confirm their presence at Cerro Prieto, established ideas about the opening of the Gulf of California and about Pacific Coast mid-Tertiary history will need to be rewritten.

  6. Integrating palaeoenvironmental and climate cyclicities - Optimizing the stratigraphic framework in the non-marine Lower Cretaceous

    NASA Astrophysics Data System (ADS)

    Sames, Benjamin

    2015-04-01

    Studies on changing paleoenvironments and climate cycles in non-marine archives of the Cretaceous greenhouse earth are hitherto rare, primarily a result of the lack of high-resolution stratigraphy and correlations to the marine record. On the other hand, recent refinements of the geological time scale have made major advances for the Cretaceous to yield a resolution comparable to that of younger Earth history. In the Cretaceous marine record is now possible to correlate and date short-term sea-level records and their possible relation to climate and/or tectonic events with appropriate resolution. Correlation in the non-marine realm ('continental' aquatic) has long been fraught with considerable problems and limitations, especially on supraregional (i.e., inter-basinal) to global scales, thus often hampering serious attempts at dating and chronological linking of events documented by the respective deposits - let alone appropriate correlation to marine successions. A new interdisciplinary project and multi-proxy study funded by the Austrian Science Fund (FWF) uses the Lower Cretaceous European record (English Wealden) as a test site for the integration of ostracod biostratigraphy and assemblage changes, and cyclostratigraphy (orbitally/climate driven cycles). Ostracods (microcrustaceans with a calcified shell) are the most useful biostratigraphical and palaeoenvironmental tool in Lower Cretaceous non-marine sequences. During the past two decades, research progress in late Mesozoic non-marine ostracods led to their extended applicability, whereas their wide dispersal ability has become a key conside-ration in their supraregional (inter-basinal to global) biostratigraphical utility. The integrative methodology applied in this project, targets the correlation of the ostracod faunal composition change with the variation of geochemical and sedimentological parameters through time and inferences on controlling (palaeoenvironmental) factors and their regulating mechanisms

  7. Meiofaunal abundances and faunal similarity on the continental rise off the coast of California

    NASA Astrophysics Data System (ADS)

    Rohal, Melissa; Thistle, David; Easton, Erin E.

    2014-11-01

    Metazoan meiofauna (e.g., nematodes, benthic copepods) play important roles in deep-sea sediment communities, but information as basic as standing stocks is not known for much of the world ocean. We therefore sampled six stations: one near the 2700-m isobath and one near the 3700-m isobath off northern, central, and southern California. We counted benthic copepods, both Desmoscolecidae and nondesmoscolecid nematodes, kinorhynchs, nauplii, and ostracods from multiple-corer samples. Nematodes from our 2700-m and 3700-m stations, and ostracods and nauplii from our 3700-m stations, were unusually abundant compared to those from other stations from comparable depths in the Pacific. Off California, the abundances of benthic copepods, kinorhynchs, and nondesmoscolecids at the 2700-m stations were significantly greater than those at the 3700-m stations. Abundance of benthic copepods was correlated with the percentage of medium sand in the sediment, so sediment texture could be important to them. That of kinorhynchs was correlated with the concentration of chloroplastic-pigment equivalents and percentage nitrogen, so consumable material from the euphotic zone could be important to them. In contrast to the usual pattern of decreasing abundance with depth, Desmoscolecidae abundance in the central region was greater at the 3700-m than at the 2700-m station. The three regions differed significantly in both kinorhynch and ostracod abundances, independently of depth. In the food-poor deep sea, animals are expected to be more abundant where food is plentiful. Unexpectedly, ostracod abundance was negatively correlated with all food variables. A possible explanation is that the natural enemies of ostracods are abundant where food is abundant. Multivariate faunal similarity at 2700 m differed significantly from that at 3700 m, independently of regions. Benthic copepods were most responsible for the difference. Regions also differed in multivariate faunal similarity independently of

  8. Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution

    PubMed Central

    Williams, Mark; Vannier, Jean; Corbari, Laure; Massabuau, Jean-Charles

    2011-01-01

    Background We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. Methodology/Principal Findings The PO2 of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO2 of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O2. Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O2 levels. The PO2 of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O2. Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO2 gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O2. Ostracods became the numerically dominant arthropod micro-benthos of

  9. The Ostracoda (Crustacea) of the Tina Menor estuary (Cantabria, southern Bay of Biscay): Distribution and ecology

    NASA Astrophysics Data System (ADS)

    Martínez-García, Blanca; Pascual, Ana; Rodríguez-Lázaro, Julio; Martín-Rubio, Maite; Rofes, Juan

    2013-10-01

    Recent ostracods from the Tina Menor estuary (northern Spain, southern Bay of Biscay) have been analysed. Twenty-five species have been identified for the first time, 20 with living individuals during the sampling period. The most abundant species are Leptocythere castanea, Leptocythere porcellanea, Loxoconcha elliptica, Cytherois fischeri, and Hemicytherura hoskini, Leptocythere psammophila and Semicytherura aff. angulata. These species are grouped into four assemblages defining different environments: muddy inner estuary with euryhaline species (L. elliptica); middle estuary with silty sand flats and low marsh environments (L. castanea, L. porcellanea and C. fischeri); sandy outer estuary with marine characteristics (H. hoskini, S. aff. angulata, Leptocythere baltica and L. psammophila); and littoral to inner shelf environment (Caudites calceolatus, H. hoskini and Callistocythere murrayi). In the middle estuary, L. castanea also delimits sandy-silty low marshes, and L. porcellanea and C. fischeri the vegetated ecosystems. Multivariate analyses with the samples and species (cluster Q-type and detrended and canonical correspondence analysis) confirm that ostracod distribution in the Tina Menor estuary is controlled by sediment grain size and by the distance to the mouth of the estuary (associated to salinity). The geographical height in relation with mean tide levels (and therefore with emersion periods) also plays an important role in distribution. The results of this study confirm ostracod validity as tide-level markers due to the presence of C. fischeri below the MHWNT (mean high water neap tide), whereas L. castanea and L. porcellanea are present between the MHWNT and MHW (mean high water) levels. Ostracods can also indicate environmental changes due to human-influenced processes. Abundant individuals of L. elliptica in some areas of the middle estuary evidence discharges of lower-salinity water from a nearby fish farm. Ostracods from the marine shelf reach the

  10. Palaeocopid and podocopid Ostracoda from the Lexington Limestone and Clays Ferry Formation (Middle and Upper Ordovician) of central Kentucky

    USGS Publications Warehouse

    Warshauer, S.M.; Berdan, J.M.

    1982-01-01

    The Middle through lower Upper Ordovician Lexington Limestone and lower part of the Clays Ferry Formation contain an abundant and diversified ostracode fauna. More than 10,000 specimens belonging to 39 genera and 53 species have been found in 73 collections made by members of the U.S. Geological Survey in cooperation with the Kentucky Geological Survey between 1961 and 1970. Five of the genera and 17 of the species are new. New taxa include the genera Gephyropsis, Ningulella, Phelobythocypris, Quasibollia, and Uninodobolba and the following species: Americoncha dubia, Ballardina millersburgia, Brevidorsa strodescreekensis, Ceratopsis asymme , trica C. fimbriata, Ctenobolbina ventrispinifera, Cystomatochilina reticulotiara, Easchmidtella sinuidorsata, Gephyropsis trachyreticulata, Jonesella gonyloba, Laccoprimitia claysferryensis, L. cryptomorphologica, Leperditella? perplexa, Ningulella paupera, Parenthatia sadievillensis, Silenis kentuckyensis, and Uninodobolba franklinensis. In addition, a new species, Quasibollia copelandi, is described from the Middle Ordovician of Ontario. The type specimens of ostracodes previously described from these formations but not represented in the recent collections are redescribed and refigured. The genus Warthinia Spivey, 1939, is reinstated for Ordovician bolliids with two to four nodes, and the genus Ceratopsis Ulrich, 1894, is reviewed with new figures of all known North American species of the genus. Forty-four collections included enough specimens to warrant quantitative analysis. The temporal and spatial distribution of the genera were defined by using Q-mode cluster analysis based on Sorensen's quantified coefficient of association. The resulting phenogram indicated the existence of eight clusters; these clusters were characterized by calculation of constancy and fidelity measures for each of the variables. Generic diversity, compound generic diversity, and lithologic associations were scanned in an attempt to delineate the

  11. A multi-proxy approach to tracing a regressive event at Ferguson's Gulf, Lake Turkana, Kenya: Implications for modern analogues to assist in interpretations of the Plio-Pleistocene record

    NASA Astrophysics Data System (ADS)

    Beck, Catherine; Feibel, Craig; Wright, James; Mortlock, Richard

    2014-05-01

    Located in the East African Rift Valley, the Turkana Basin has long been central to our understanding of how early hominins evolved. In particular, there is great curiosity as to the relationship between the paleoenvironment/paleoclimate conditions and evolution. Historical records aid in the interpretation of Plio-Pleistocene sediments by creating the opportunity to ground truth assumptions through the use of modern analogues. This project uses high-resolution, multi-proxy records from a series of short cores spanning the Little Ice Age to the modern, to suggest one possible model for how regressive events are recorded in lacustrine sequences. Because Lake Turkana is hydrologically closed, changes in lake level affect the water chemistry and thereby the ecosystems that depend upon it. Ferguson's Gulf is a 13 km2, shallow embayment located on the western shore of Lake Turkana. The gulf is connected to the rest of the lake by a narrow mouth on its northern end which is ~1 m deep. Therefore, relatively minor drops in lake level have the potential to restrict flow from Lake Turkana into Ferguson's Gulf, creating localized evaporative water chemistry which effects the suitability of this area for sustaining various benthic populations. Six short cores collected in 2011 and 2012 were picked for ostracods at 1-5 cm intervals to study the changes in assemblages and total abundances through time. An age model, generated using radiocarbon dating of ostracods, demonstrated that the record extending into the Little Ice Age (1550-1850 AD), a period when wetter conditions prevailed within the Turkana Basin. The ostracod faunal results were compared with sedimentology/stratigraphy, XRF data, and stable isotope analysis on ostracod shells for a multiproxy approach to reconstructing hydrologic conditions during the past ~500 years. The Ferguson's Gulf record can be subdivided into three bins based on the ostracod assemblages. The lowest third of the core shows high ostracod total

  12. Reconstructing the climatic ultrastructure and aquatic biotic communities response to Heinrich stadials in the continental northern Neotropics

    NASA Astrophysics Data System (ADS)

    Cohuo, Sergio; Macario, Laura; Sylvestre, Florence; Pailles, Christine; Kutterolf, Steffen; Pérez, Liseth; Curtis, Jason; Schwalb, Antje

    2016-04-01

    Heinrich stadials (HS) are recognized as fast-acting "pulses" of global rapid environmental change that affect the climate and cause alterations in species composition and distribution. Past changes in aquatic ecosystems due to HSs may be an analog for future disruptions caused by climate change in the Neotropics. Our aim is to provide high resolution water temperature and conductivity records for HSs (HS1-HS6) in the northern Neotropics and identify their effects on aquatic communities. We analyzed the geochemical sediment composition (TIC and TOC) and quantified ostracode and diatom fossil abundances in cores PI-6 (73m long, from71m water depth) and PI-2 (84m long and from 54m water depth) from Lake Petén Itzá, Guatemala. Sediment cores were dated using a combination of radiocarbon and tephra chronology. Taxonomical analysis revealed that the ostracode fauna through all HSs had an exclusive tropical composition, reflecting that water temperatures remained warm, likely within the current tolerant range (26-33°C) observed for modern species inhabiting Central American lakes. Because of these warm conditions on the lake ecosystem, we infer that there was not a large change in temperatures as suggested by Hodell et al. (2012), but a small on such at the 5°C suggested by Correa-Metrio et al. (2012). Sediments during HSs are dominated by gypsum, suggesting variable water solute composition. Low TIC and TOC values during HSs indicate that these variations resulted from a decrease in precipitation and prevailing dry conditions. Bioproxy composition however, suggests sharp climatic transitions from humid to arid (HS5, HS3and H1) and from arid to humid (HS4, HS2). HS6 (63.2-60.1 ka BP) was characterized by domination of benthic diatoms and nektobenthic Cypria petenensis, Paracythereis opesta and Pseudocandona sp. ostracode species, suggesting low lake levels with predominance of littoral conditions. HS5 (50-47ka BP), HS3 (32.7-31.3ka BP) and HS1 (18-15.6ka BP) were

  13. In vivo and in situ synchrotron radiation-based μ-XRF reveals elemental distributions during the early attachment phase of barnacle larvae and juvenile barnacles.

    PubMed

    Senkbeil, Tobias; Mohamed, Tawheed; Simon, Rolf; Batchelor, David; Di Fino, Alessio; Aldred, Nick; Clare, Anthony S; Rosenhahn, Axel

    2016-02-01

    Barnacles are able to establish stable surface contacts and adhere underwater. While the composition of adult barnacle cement has been intensively studied, far less is known about the composition of the cement of the settlement-stage cypris larva. The main challenge in studying the adhesives used by these larvae is the small quantity of material available for analysis, being on the order of nanograms. In this work, we applied, for the first time, synchrotron radiation-based μ-X-ray fluorescence analysis (SR-μ-XRF) for in vivo and in situ analysis of young barnacles and barnacle cyprids. To obtain biologically relevant information relating to the body tissues, adhesives, and shell of the organisms, an in situ sample environment was developed to allow direct microprobe investigation of hydrated specimens without pretreatment of the samples. In 8-day-old juvenile barnacles (Balanus improvisus), the junctions between the six plates forming the shell wall showed elevated concentrations of calcium, potassium, bromine, strontium, and manganese. Confocal measurements allowed elemental characterization of the adhesive interface of recently attached cyprids (Balanus amphitrite), and substantiated the accumulation of bromine both at the point of initial attachment as well as within the cyprid carapace. In situ measurements of the cyprid cement established the presence of bromine, chlorine, iodine, sulfur, copper, iron, zinc, selenium, and nickel for both species. The previously unrecognized presence of bromine, iron, and selenium in the cyprid permanent adhesive will hopefully inspire further biochemical investigations of the function of these substances. PMID:26715248

  14. Characterization of Arginine Kinase in the Barnacle Amphibalanus Amphitrite and Its Role in the Larval Settlement.

    PubMed

    Zhang, Gen; Yan, Guo-Yong; Yang, Xiao-Xue; Wong, Yue-Him; Sun, Jin; Zhang, Yu; He, Li-Sheng; Xu, Ying; Qian, Pei-Yuan

    2016-06-01

    Energy metabolism is a key process in larval settlement of barnacles, but the underlying molecular mechanisms remain ambiguous. Arginine kinase (AK) mainly participates in energy metabolism in invertebrates. So far, its roles in barnacles have not been studied. In the present study, we raised an antibody against AK from Amphibalanus amphitrite Darwin to characterize the roles of AK in the larval settlement process. Among the developmental stages, AK was highly expressed during the cypris stage. Along with the aging process in cyprids, the level of AK decreased. The immunostaining results showed that AK was localized to muscular tissues in cyprids, including antennules, antennular muscles, and thoracic limbs. The larval settlement rate decreased and larval movement was inhibited in response to treatments with high concentrations of AK inhibitors (rutin and quercetin). These results demonstrated that AK was involved in the larval settlement of A. amphitrite through mediating energy supply in muscle tissues. Moreover, further analysis indicated that both the p38 MAPK and NO/cGMP pathways positively mediated the expression of AK in cyprids. PMID:27245369

  15. A petromagnetic study of Miocene rocks bearing micro-organic material and the magnetic mineral greigite (Sokolov and Cheb basins, Czechoslovakia)

    NASA Astrophysics Data System (ADS)

    Krs, M.; Krsová, M.; Pruner, P.; Zeman, A.; Novák, F.; Jansa, J.

    1990-10-01

    The Middle Miocene sediments of the Cypris series from the Sokolov and Cheb brown-coal basins (western Bohemia) were subjected to petromagnetic investigation. During the laboratory thermal treatment, at a temperature of 350-400°C, the samples rich in micro-organic material changed into carbonified samples which exhibited similar physical and technological properties to coal samples collected from the underlying coal seam. The experimental results may have a bearing on several problems concerning the origin of fossil fuels and highlight specific rock properties which may have potential for identifying the micro-organic content. A strongly magnetic mineral greigite Fe 3S 4 was identified in magnetic zones above the coal seam. The authigenic mineral greigite occurs in strata of greater thickness and it was found that a reducing environment, generated by the presence of organic matter, was required for the formation of the greigite. Metastable properties and the low coercivity spectra of this mineral are adverse for palaeomagnetic investigations.

  16. Charged hydrophilic polymer brushes and their relevance for understanding marine biofouling.

    PubMed

    Yandi, Wetra; Mieszkin, Sophie; di Fino, Alessio; Martin-Tanchereau, Pierre; Callow, Maureen E; Callow, James A; Tyson, Lyndsey; Clare, Anthony S; Ederth, Thomas

    2016-07-01

    The resistance of charged polymers to biofouling was investigated by subjecting cationic (PDMAEMA), anionic (PSPMA), neutral (PHEMA-co-PEG10MA), and zwitterionic (PSBMA) brushes to assays testing protein adsorption; attachment of the marine bacterium Cobetia marina; settlement and adhesion strength of zoospores of the green alga Ulva linza; settlement of barnacle (Balanus amphitrite and B. improvisus) cypris larvae; and field immersion tests. Several results go beyond the expected dependence on direct electrostatic attraction; PSPMA showed good resistance towards attachment of C. marina, low settlement and adhesion of U. linza zoospores, and significantly lower biofouling than on PHEMA-co-PEG10MA or PSBMA after a field test for one week. PDMAEMA showed potential as a contact-active anti-algal coating due to its capacity to damage attached spores. However, after field testing for eight weeks, there were no significant differences in biofouling coverage among the surfaces. While charged polymers are unsuitable as antifouling coatings in the natural environment, they provide valuable insights into fouling processes, and are relevant for studies due to charging of nominally neutral surfaces. PMID:27125564

  17. Atomic force microscopy of the morphology and mechanical behaviour of barnacle cyprid footprint proteins at the nanoscale

    PubMed Central

    Phang, In Yee; Aldred, Nick; Ling, Xing Yi; Huskens, Jurriaan; Clare, Anthony S.; Vancso, G. Julius

    2010-01-01

    Barnacles are a major biofouler of man-made underwater structures. Prior to settlement, cypris larvae explore surfaces by reversible attachment effected by a ‘temporary adhesive’. During this exploratory behaviour, cyprids deposit proteinaceous ‘footprints’ of a putatively adhesive material. In this study, footprints deposited by Balanus amphitrite cyprids were probed by atomic force microscopy (AFM) in artificial sea water (ASW) on silane-modified glass surfaces. AFM images obtained in air yielded better resolution than in ASW and revealed the fibrillar nature of the secretion, suggesting that the deposits were composed of single proteinaceous nanofibrils, or bundles of fibrils. The force curves generated in pull-off force experiments in sea water consisted of regions of gradually increasing force, separated by sharp drops in extension force manifesting a characteristic saw-tooth appearance. Following the relaxation of fibrils stretched to high strains, force–distance curves in reverse stretching experiments could be described by the entropic elasticity model of a polymer chain. When subjected to relaxation exceeding 500 ms, extended footprint proteins refolded, and again showed saw-tooth unfolding peaks in subsequent force cycles. Observed rupture and hysteresis behaviour were explained by the ‘sacrificial bond’ model. Longer durations of relaxation (>5 s) allowed more sacrificial bond reformation and contributed to enhanced energy dissipation (higher toughness). The persistence length for the protein chains (LP) was obtained. At high elongation, following repeated stretching up to increasing upper strain limits, footprint proteins detached at total stretched length of 10 µm. PMID:19570797

  18. Antennulary sensory organs in cyprids of Octolasmis and Lepas (Crustacea: Thecostraca: Cirripedia: Thoracica): a scanning electron microscopic study.

    PubMed

    Blomsterberg, Mikkel; Høeg, Jens T; Jeffries, William B; Lagersson, Niklas C

    2004-05-01

    Cypris larvae of the pedunculate barnacles Octolasmis angulata (Poecilasmatidae), Lepas australis, L. pectinata, and Dosima fascicularis (Lepadidae) were studied with scanning electron microscopy, focusing on the sensory setae and the attachment disc on the antennules. The antennules of O. angulata did not exhibit any remarkable trait, but carry the same number of setae as seen in most other thoracicans. The third segment is bell-shaped and quite distinct from the second and its attachment disc is surrounded by a skirt. We found several potential synapomorphies in antennulary morphology between cyprids of the lepadid species but none of them were shared with the cyprids of Octolasmis; the list of unique lepadid characters includes: one additional, preaxial seta on the second segment; multiple similar (up to eight) postaxial setae (PS3) on the third segment, unlike all other thoracicans, where there is only a single PS3; the third segment consists almost entirely of the attachment disc, which is distended and surrounded by two parallel rows of radial setae; on the fourth segment the terminal seta E is diminutive. We found no traits in cyprids of Octolasmis that seem to be adaptations to their attachment site within the branchial chamber of swimming crabs and, in particular, no similarities with cyprids of rhizocephalan barnacles, many of which also attach in the gill chamber. The synapomorphies between cyprids of the lepadid species may be adaptations to their life in the neuston. PMID:15108154

  19. Holocene paleoclimate inferred from salinity histories of adjacent lakes in southwestern Sicily (Italy)

    USGS Publications Warehouse

    Curry, B Brandon; Henne, Paul; Mezquita-Joanes, Francesc; Marrone, Federico; Pieri, Valentina; La Mantia, Tommaso; Calo, Camilla; Tinner, Willy

    2016-01-01

    Marked uncertainties persist regarding the climatic evolution of the Mediterranean region during the Holocene. For instance, whether moisture availability gradually decreased, remained relatively constant, or increased during the last 7000 years remains a matter of debate. To assess Holocene limnology, hydrology and moisture dynamics, the coastal lakes Lago Preola and Gorgo Basso, located in southwestern Sicily, were investigated through several stratigraphic analyses of ostracodes, including multivariate analyses of assemblages, transfer functions of salinity, and biochemical analyses of valves (Sr/Ca, δ18O and δ13C). During the early Holocene, the Gorgo Basso and Lago Preola ostracode records are similar. After an initial period of moderate salinity (1690–6100 mg/l from ca. 10,000–8190 cal yr BP), syndepositional or diagenetic dissolution of ostracode valves suggests that salinity declined to <250 mg/L from ca. 8190 to 7000 cal yr BP at both sites. After ca. 6250 cal yr BP, the ostracode records are strikingly different. Lago Preola became much more saline, with paleosalinity values that ranged from 2270 to about 24,420 mg/L. We suggest that Lago Preola's change from a freshwater to mesosaline lake at about 6250 cal yr BP was related to sea level rise and resulting intrusion of seawater-influenced groundwater. In contrast, Gorgo Basso remained a freshwater lake. The salinity of Gorgo Basso declined somewhat after 6250 cal yr BP, in comparison to the early Holocene, ranging from about 550 to 1680 mg/L. Cypria ophtalmica, a species capable of rapid swimming and flourishing in waters with low dissolved oxygen levels, became dominant at approximately the time when Greek civilization took root in Sicily (2600 cal yr BP), and it completely dominates the record during Roman occupation (roughly 2100 to 1700 cal yr BP). These freshwater conditions at Gorgo Basso suggest high effective moisture when evergreen olive-oak forests collapsed in response

  20. Pleistocene-Holocene lower bathyal benthic foraminifera: A pilot study in Keathley Canyon, northwestern Gulf of Mexico

    SciTech Connect

    Jones, M.J. )

    1991-03-01

    Recent work on the shelf and upper slope have linked the distribution of benthic foraminifera to the presence of several Gulf of Mexico water masses. A pilot study consisting of three piston cores from lower bathyal depths (1,308 m, 1,543 m, 1,815 m) was undertaken to examine the distribution of benthic foraminifera across the Pleistocene-Holocene boundary and at several depths within the lower slope environment. The primary objective of this study was to test the hypothesis that abundance variations of benthic foraminifera can be used to refine the bathymetric zonation of deep Gulf of Mexico depositional environments based on their water mass associations. Preliminary results from this study support this hypothesis by showing a distinct variation in benthic foraminiferal abundances between the shallower cores (1,308 m, 1,543 m) and the deeper core (1,815 m). The cores from 1,308 m and 1,543 m contain a fauna that exhibits a moderate abundance (ca. 10-15%) of several species: Bolivina lowmania, Bulimina aculeata, Cassidulina subglobosa, Gyroidina soldanii and Oridorsalis spp., while the core from 1815 m contains a fauna strongly dominated (25-60%) by two species: Eponides turgidus and Nuttallides decorata. Abundance variations downcore or across the Pleistocene-Holocene boundary are subtle but present nonetheless. The preliminary results from this study suggest that the distribution of deep Gulf of Mexico benthic foraminifera may be related to the distribution of water masses comprising the deep gulf and that further bathymetric refinement of the lower slope may be possible.

  1. Deep-sea ecosystem response to the Middle Eocene Climate Optimum (MECO) in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bunzel, Dorothea; Schmiedl, Gerhard; Friedrich, Oliver

    2016-04-01

    We investigated the benthic foraminiferal diversity and species composition from North Atlantic IODP Site U1408 in order to document changes in deep-water circulation and organic matter fluxes across the Middle Eocene Climate Optimum (MECO). Site U1408 was drilled at a present water depth of 3022 m southeast of the coast of Newfoundland. The benthic foraminiferal faunas are characterized by generally high species diversity suggesting favorable environmental conditions throughout the studied interval. Among a total of 193 benthic foraminiferal taxa the most dominant genera include Nuttallides, Oridorsalis, Cibicidoides, Pullenia, Anomalinoides, Globocassidulina and Gyroidinoides. Increased abundances of elongate-cylindrical infaunal species suggest approximately 460 ka duration of the MECO (from around 40.19 to 39.73 Ma) and the presence of slightly less ventilated bottom waters and elevated food availability during this time interval. The duration of the MECO also coincides with the presence of the planktonic foraminifer Orbulinoides beckmanni, which therefore is used as an Eocene biostratigraphy marker defining the end of the warm interval with its Last Appearance Datum. Changes in the benthic foraminiferal fauna probably reflect the onset of deep-water formation in the northern North Atlantic Ocean as response to the long-term climatic cooling trend of the middle Eocene. The intensification of deep-water currents and increased influence of cold and well-ventilated deep-water masses is reflected by increased importance of the Nuttallides truempyi-fauna. Superimposed on this long-term faunal trend are changes in the distribution of Globocassidulina subglobosa at a period of approximately 200 ka suggesting an eccentricity forcing of deep-water formation and associated food quality at the sea floor.

  2. Regional primary productivity differences off Morocco (NW-Africa) recorded by modern benthic foraminifera and their stable carbon isotopic composition

    NASA Astrophysics Data System (ADS)

    Eberwein, A.; Mackensen, A.

    2006-08-01

    The influence of different primary productivity regimes on live (Rose Bengal stained) and dead benthic foraminiferal distribution, as well as on the stable carbon isotopic composition of foraminiferal tests, was investigated in sediment surface samples (0-1 cm) from the upwelling region off Morocco between Cape Ghir (31°N) and Cape Yubi (27°N). A combination of factor analysis, detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) was applied to the benthic foraminiferal data sets. Five major assemblages for both the live and dead fauna were revealed by factor analysis. In the cape regions organic matter fluxes are enhanced by high chlorophyll- α concentrations in the overlying surface waters. Here, benthic foraminiferal faunas are characterized by identical live and dead assemblages, high standing stocks, and low species δ13C values, indicating constant year-round high productivity. Bulimina marginata dominates the unique fauna at the shallowest station off Cape Ghir indicating highest chlorophyll- a concentrations. Off both capes, the succession of the Bulimina aculeata/ Uvigerina mediterranea assemblage, the Sphaeroidina bulloides/ Gavelinopsis translucens assemblage, and the Hoeglundina elegans assemblage from the shelf to the deep sea reflects the decrease in chlorophyll- a concentrations, hence the export flux. In contrast, the area between the capes is characterized by differently composed live and dead assemblages, low standing stocks, and less depleted δ13C values, thus reflecting low primary productivity. High foraminiferal numbers of Epistominella exigua, Eponides pusillus, and Globocassidulina subglobosa in the dead fauna indicate a seasonally varying primary productivity signal. Significantly lower mean δ13C values were recorded in Bulimina mexicana, Cibicidoides kullenbergi, H. elegans, U. mediterranea and Uvigerina peregrina. Cibicidoides wuellerstorfi is a faithful recorder of bottom water δ13C in the Canary

  3. Live (Rose Bengal stained) foraminiferal faunas from the northern Arabian Sea: faunal succession within and below the OMZ

    NASA Astrophysics Data System (ADS)

    Caulle, Clemence; Koho, Karoliina; Mojtahid, Meryem; Reichart, Gert-Jan; Jorissen, Frans

    2014-05-01

    Live (Rose Bengal stained) benthic foraminifera from the Murray Ridge, within and below the northern Arabian Sea Oxygen Minimum Zone (OMZ), were studied in order to determine the relationship between faunal composition, bottom-water oxygenation (BWO), pore-water chemistry and organic matter (organic carbon and phytopigment) distribution. A series of multicores were recovered from a ten-station oxygen (BWO: 2µM - 78µM) and bathymetric (885 - 3010m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63-125µm, 125-150µm and >150µm). The larger foraminifera (>125µm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63-125µm fraction, calcareous taxa were more abundant, especially in the core of the OMZ. On the basis of a Principal Components Analysis, three foraminiferal groups were identified and correlated to the environmental parameters by Canonical Correspondence Analysis. The faunas from the shallowest stations, in the core of the OMZ (BWO: 2µM), were composed of "low oxygen" species, typical of the Arabian Sea OMZ (e.g., Rotaliatinopsis semiinvoluta, Praeglobobulimina sp., Bulimina exilis, Uvigerina peregrina type parva). These taxa are adapted to the very low BWO conditions and to high phytodetritus supplies. The transitional group, typical for the lower part of the OMZ (BWO: 5-16µM), is composed of species, which are tolerant as well to low-oxygen concentrations, but may be less critical with respect to organic supplies (e.g. Globocassidulina subglobosa, Ehrenbergina trigona). Below the OMZ (BWO: 26-78µM), where food availability is more limited and becomes increasingly restricted to surficial sediments, cosmopolitan calcareous taxa were present, such as Bulimina aculeata, Melonis barleeanus, Uvigerina peregrina and Epistominella exigua. Miliolids were uniquely observed in this last zone, reflecting the higher BWO and/or lower organic

  4. Benthic foraminifera across the Eocene-Oligocene boundary in the Southeast Atlantic (Site 1263)

    NASA Astrophysics Data System (ADS)

    Fenero, R.; Thomas, E.

    2013-05-01

    During the Eocene-Oligocene (E-O) boundary interval the world gradually transitioned from a Greenhouse to an Icehouse state, with the development of Antarctic continental ice sheets at sea-level (Zachos et al., 2001). The interval of maximum ice-sheet volume commonly called Oi-1 (e.g., Miller et al., 2009), is recognized by a maximum in the deep-sea benthic foraminiferal oxygen isotope (δ18O) values. There were two main steps of ice-sheet growth and cooling ca. 33.5-33.7 Ma (e.g., Eldrett et al., 2009). We traced deep-sea environmental changes in SE Atlantic Ocean (Walvis Ridge) through a quantitative analysis of benthic foraminiferal assemblages at South Atlantic Site 1263. Faunal assemblages and backtracking place the paleodepth at about 2000 m (upper abyssal). The transition into glaciation event Oi-1 is characterized by very highly seasonal productivity, as indicated by high abundances of Epistominella exigua, and Epistominella vitrea. The abundances of these species and thus seasonality gradually declined during Oi-1, when bottom currents may have become more intensified as indicated by high abundances of Globocassidulina subglobosa. During Oi-1, the overall food supply as indicated by percentage of unfaunal species was high, and the carbonate corrosivity of the bottom waters increased, as indicated by high abundances of Nuttallides umbonifera. This corrosivity reached a maximum about 100 kyr after Oi-1. Relative abundances of various uniserial taxa with complex apertures (e.g., Stilostomella, Pleurostomella spp.) declined across the E-O boundary interval, as at many sites globally. This decline could indicate a decrease in a specific food source (e.g. Hayward et al., in press), with changing phytoplankton communities across the E/O boundaries. Our research thus indicates that changing oceanic productivity as well as deep-water characteristics influenced deep-sea biota across the E-O boundary, and that high seasonality of productivity extended to the middle

  5. Benthic foraminiferal distribution in deep-water periplatform carbonate environments

    SciTech Connect

    Martin, R.E.

    1987-05-01

    In contrast to clastic depositional environments, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 sediment samples (piston core top and grab) collected along two transverses approximately 25 km apart across the northern (windward) margin of Little Bahama Bank at depths of 275 to 1135 m. Most species exhibit great variation in abundance with depth. However, Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators (Spearman's r > 0.91; p < 0.005), being most abundant at depths > 1000 m, and correspond to lower slope (> 900 m) periplatform aprons. Individual foraminiferal suborders (Miliolina, Rotaliina, Textulariina) show no consistent depth-related trends. However, certain operational taxonomic groups, such as reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are significant more abundant at depths < 300 m (95% C.I.: 2.6 +/- 2.2% and 6.9 +/- 2.7%, respectively) than at greater depths (95% C.I.: 0.3 +/- 0.2% and 2.0 +/- 0.8%; Mann-Whitney U, p < 0.01), reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines (i.e., suborder Miliolina minus peneroplids and soritids) and rosalinids and discorbids (suborder Rotaliina) are also more abundant at depths < 300 m (95% C.I.: 27.5 +/- 7.4% and 32.6 +/- 8.5%, respectively) than at greater depths (95% C.I.: 10.0 +/- 3.9% and 1.5 +/- 1.6%; Mann-Whitney U, p < 0.01) and are winnowed from the carbonate platform. Assemblages exhibit greatest variation in diversity (species number, s; Shannon-Weaver, H'; evenness, J') at depths > 900 m; indices for shallower assemblages tend to be grouped more tightly at relatively high values.

  6. Carbon and oxygen isotopic records from Lake Tuosu over the last 120 years in the Qaidam Basin, Northwestern China: The implications for paleoenvironmental reconstruction

    NASA Astrophysics Data System (ADS)

    Li, Xiangzhong; Zhou, Xin; Liu, Weiguo; Wang, Zheng; He, Yuxin; Xu, Liming

    2016-06-01

    Isotopic compositions of total organic carbon (TOC) and authigenic carbonate in lakes have been widely used to reconstruct paleoclimatic changes and the depositional environments of lake sediments. However, since these proxies are often controlled by multiple environmental factors, detailed examinations of modern environmental processes is necessary before further applying them into paleoclimatic studies, especially in arid/semi-arid northwestern China. Here we generate High-resolution multi-proxy sedimentary records from Lake Tuosu, a hydrologically closed, saline and alkaline lake located at the north margin of the Qaidam Basin, through analysis of carbon isotope of TOC, and δ18O and δ13C values of ostracods over the last 120 years. Together with the meteorological data (precipitation and temperature), lake area record, and other tree-ring evidence, we examine how these sedimentary indices respond to changes in hydrologic balance and climate at interannual to decadal timescales. We found that sedimentary δ13Corg values resemble the variation of lake areas of Lake Tuosu over the last 40 years, suggesting that δ13Corg values would be an ideal indicator of lake area/level fluctuations and thus effective moisture variations (precipitation vs. evaporation). However, ostracod δ18O, which was previously used as proxies of effective precipitation, is not well correlated with δ13Corg values in Lake Tuosu. Therefore, the changes of ostracod δ18O values cannot be straightforwardly explained as the effective precipitation. Instead, the isotopic composition of carbonate would be additionally controlled by other factors including isotopic compositions of input water and drainage pattern.

  7. Inconsistent Climate Inferences between Pollen and other Paleontological, Geochemical, and Geophysical Proxies in Late Pleistocene Lacustrine Sediments from Summer Lake, Oregon, Western Great Basin

    NASA Astrophysics Data System (ADS)

    Heaton, E.; Thompson, G.; Negrini, R. M.; Wigand, P. E.

    2015-12-01

    This study has established a high resolution paleoclimate record from western Great Basin pluvial Summer Lake, Oregon during the late Pleistocene Mono Lake Excursion (~34 ka), Dansgaard-Oeschger (D-O) interstadials 7 and 8, and the end of Heinrich Even 4 (~38 ka). Proxies of grain-size, carbon/nitrogen (C/N) ratio, ostracode analysis and palynology from a depocenter core show new results regarding high amplitude, high frequency changes in lake level, precipitation and temperature which correspond directly with colder/warmer and respectively drier/wetter climates as documented with Northern Atlantic Greenland ice core data. The granulometry, geochemical, and ostracode results consistently demonstrate the correspondence of low lake conditions and colder water temperatures during D-O stadials and warmer/wetter climate during interstadials. These results are contradicted by the pollen results. Existence of cold temperature spores Botrychium and Selaginella coincide with increases in Artemisia, Atriplex, Sarcobatus, Cyperaceae and decreases in Pinus, also suggesting periods of colder/drier climate and shallower lake levels but the timing does not match that of those conditions inferred by the other methods. Granulometry, geochemical, and ostracode proxies denote cold periods and low lake levels roughly between 37.5-35.6 ka and 34.6-33.8 ka. Pollen analysis suggests near-opposite time intervals with cold periods roughly 38-37.5 ka, 35.6-35 ka. This pollen inconsistency suggests the possibility of (1) a millennial-scale lag response of vegetation to climate change, (2) runoff from stadial precipitation causing influx in pollen abundances and variety found in the depocenter core, or (3) turbulent mixing from shallow lake level causing resuspension and redeposition of pollen (Bradley 1999).

  8. A quantitative micropaleontologic method for shallow marine peleoclimatology: Application to Pliocene deposits of the western North Atlantic Ocean

    USGS Publications Warehouse

    Cronin, T. M.; Dowsett, H.J.

    1990-01-01

    A transfer function was developed to estimate summer and winter paleotemperatures for arctic to tropical regions of the western North Atlantic Ocean using fossil ostracode assemblages. Q-mode factor analysis was run on ostracode assemblages from 100 modern bottom sediment samples from continental shelves of North America, Greenland and the Caribbean using 59 ostracode taxa. Seven factors accounting for 80% of the variance define assemblages that correspond to frigid, subfrigid, cold temperate, mild temperate, warm temperate, subtropical and tropical climatic zones. Multiple regression of the factor matrix against observed February and August bottom temperatures yielded an astracode transfer function with an accuracy of about ??2??C. The transfer function was used to reconstruct middle Pliocene (3.5-3.0 Ma) shallow marine climates of the western North Atlantic during the marine transgression that deposited the Yorktown Formation (Virginia and North Carolina), the Duplin Formation (South and North Carolina) and the Pinecrest beds (Florida). Middle Pliocene paleowater temperatures in Virginia averaged 19??C in August and 13.5??C in February, about 5??C to 8??C warmer than at comparable depths off Virginia today. August and February water temperatures in North Carolina were 23??C and 13.4??C, in South Carolina about 23??C and 13.5??C and in southern Florida about 24.6??C and 15.4??C. Marine climates north of 35??N were warmer than today; south of 35??N, they were about the same or slightly cooler. Thermal gradients along the coast were generally not as steep as they are today. The North Atlantic transfer function can be applied to other shallow marine Pliocene and Pleistocene deposits of eastern North America. ?? 1990 Elsevier Science Publishers B.V.

  9. Microfossil zonation and correlation of nonmarine Triassic of southwestern United States

    SciTech Connect

    Kietzke, K.K. )

    1989-09-01

    Recent studies of the nonmarine Triassic in New Mexico and adjacent states by the New Mexico Museum of Natural History have resulted in a data base that for the first allows the use of calcareous microfossils for zonation of the Moenkopi and Chinle formations. Three biostratigraphic assemblages have been recognized thus far: Moenkopi, lower Chinle, and upper Chinle. The Middle Triassic Moenkopi assemblage is characterized by the charophyte Porochara, uncoiled species of Spirorbis, and the presence of the ostracod genus Darwinuloides. The Upper Triassic lower Chinle assemblage is present in the lower shale member of the Chinle Formation. It is characterized by lacking a charophyte component and in containing an exceptionally large species of Darwinula. The upper Chinle assemblage is present in the upper shale and Redonda members of the Chinle Formation and in the Sloan Canyon Formation. It contains the charophyte Stellatochara, a diverse assemblage of darwinulid ostracods, the ostracod genus Lutkevichinella, and a generally coiled species of Spirorbis. These three microfossil assemblages contain several elements of apparent cosmopolitan distribution and should greatly facilitate long-range correlations. Initial correlations suggest the Moenkopi can be correlated with the middle Bundsandstein of Europe and the Lower Triassic of the Caspian depression of the Soviet Union. The lower Chinle assemblage appears to be restricted to the southwestern US with no known correlatives elsewhere. The upper Chinle assemblage contains elements in common with the middle and upper Keuper of Europe and the Upper Triassic Wayaobu Formation of Shaanxi, China. As more collections are made and studied, correlations with other Triassic assemblages should increase in refinement and utility. Additionally, the paleoecologic aspects of these assemblages should help greatly in refining Triassic paleoenvironmental interpretations.

  10. Microfaunal evidence of age and depositional environments of the Cerro Prieto section (Plio-Pleistocene), Baja California, Mexico

    SciTech Connect

    Ingle, J.C. Jr.

    1982-01-01

    Microfossils including benthic and planktic foraminifera, ostracodes, calcareous algae, fish skeletal material, and fragments of pelecypods were found in 14 core samples from depths of 185 to 1952 m in the Cerro Prieto geothermal field, providing evidence of both the age and depositional history of sediments comprising the 3000-m-thick Pliocene and Pleistocene section in this area. Ostracodes of brackish water and marine origin constitute the most common microfossils present in this sequence occurring in 8 samples; in situ littoral and neritic species of benthic foraminifera occur in 5 samples with planktic species present in 2 samples. Distributional patterns of ostracodes and foraminifera together with previously analyzed lithofacies (Lyons and van de Kamp, 1980) indicate that the Cerro Prieto section represents an intertonguing complex of alluvial, deltaic, estuarine, and shallow marine environments deposited along the front of the Colorado River delta as it prograded across the Salton Trough during Pliocene and Pleistocene time. Foraminiferal evidence indicates that a sand and shale unit commonly present at depths between 700 and 1100 m represents a significant mid-Pleistocene marine incursion in the Cerro Prieto area. Tentative correlation of the Cerro Prieto section with the well dated Palm Springs Formation of the Imperial Valley, California area suggests that the Pliocene/Pleistocene boundary occurs at a depth of approximately 2000 m in the area of well M-93. Reworked specimens of Cretaceous foraminifera and fragments of the Cretaceous pelecypod Inoceramus were found in five samples further substantiating the Colorado Plateau provenance of a significant portion of the Colorado River deltaic sediments in the Cerro Prieto area.

  11. Cryptic Species in Putative Ancient Asexual Darwinulids (Crustacea, Ostracoda)

    PubMed Central

    Schön, Isa; Pinto, Ricardo L.; Halse, Stuart; Smith, Alison J.; Martens, Koen; Birky, C. William

    2012-01-01

    Background Fully asexually reproducing taxa lack outcrossing. Hence, the classic Biological Species Concept cannot be applied. Methodology/Principal Findings We used DNA sequences from the mitochondrial COI gene and the nuclear ITS2 region to check species boundaries according to the evolutionary genetic (EG) species concept in five morphospecies in the putative ancient asexual ostracod genera, Penthesilenula and Darwinula, from different continents. We applied two methods for detecting cryptic species, namely the K/θ method and the General Mixed Yule Coalescent model (GMYC). We could confirm the existence of species in all five darwinulid morphospecies and additional cryptic diversity in three morphospecies, namely in Penthesilenula brasiliensis, Darwinula stevensoni and in P. aotearoa. The number of cryptic species within one morphospecies varied between seven (P. brasiliensis), five to six (D. stevensoni) and two (P. aotearoa), respectively, depending on the method used. Cryptic species mainly followed continental distributions. We also found evidence for coexistence at the local scale for Brazilian cryptic species of P. brasiliensis and P. aotearoa. Our ITS2 data confirmed that species exist in darwinulids but detected far less EG species, namely two to three cryptic species in P. brasiliensis and no cryptic species at all in the other darwinulid morphospecies. Conclusions/Significance Our results clearly demonstrate that both species and cryptic diversity can be recognized in putative ancient asexual ostracods using the EG species concept, and that COI data are more suitable than ITS2 for this purpose. The discovery of up to eight cryptic species within a single morphospecies will significantly increase estimates of biodiversity in this asexual ostracod group. Which factors, other than long-term geographic isolation, are important for speciation processes in these ancient asexuals remains to be investigated. PMID:22802945

  12. Late Pliocene climate change 3.4-2.3 Ma: paleoceanographic record from the Yabuta Formation, Sea of Japan

    USGS Publications Warehouse

    Cronin, T. M.; Kitamura, A.; Ikeya, Noriyuki; Watanabe, M. E.; Kamiya, T.

    1994-01-01

    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. ?? 1994.

  13. Sub-Decadal Resolution in Sediments of Late Miocene Lake Pannon Reveals Speciation of Cyprideis (Crustacea, Ostracoda)

    PubMed Central

    Gross, Martin; Piller, Werner E.

    2015-01-01

    Late Miocene "Lake Pannon" (~11.3 Ma) was a remnant of the Central Paratethyan Sea. Successive freshening and constantly changing environmental conditions, like oxygenation, nutrition and substrate led to a well-documented radiation in molluscs and ostracods. Among ostracods (small crustaceans), Cyprideis is one of the most common genera in "Lake Pannon", as well as in several other ancient lakes, showing numerous adaptations and speciations. Here, we present high-resolution data from an early transgression of "Lake Pannon" in the Eastern Styrian Basin (SE Austria). Mataschen clay pit is in the focus of geologic and paleontologic research since 20 years and its geologic and paleoecologic evolution is well-documented. We drilled five cores covering a ~2.3 m long section and completely sampled it in 5-mm thick intervals to reconstruct minute changes in the ostracod fauna over a transgression of a brackish water body. The dominant genus, Cyprideis, is represented by three species C. mataschensis, C. kapfensteinensis and C. ex gr. pannonica. Through morphometric analyses we highlight the variance of each taxon and suggest that there is no direct ecologic control on size or shape. Furthermore, we found a second, co-occurring morphotype of C. kapfensteinensis which is directly related to an elevation of salinities above 13 psu. The presence of two intermediate specimens between the two morphotypes in the sample directly below the first appearance of C. kapfensteinensis B leads us to the conclusion that we are facing a speciation event leading to four sympatric species of Cyprideis. PMID:25902063

  14. Diverse Nonmarine Biota from the Whidbey Formation (Sangamonian) at Point Wilson, Washington

    NASA Astrophysics Data System (ADS)

    Karrow, Paul F.; Ceska, Adolph; Hebda, Richard J.; Miller, Barry B.; Seymour, Kevin L.; Smith, Alison J.

    1995-11-01

    Previously undescribed plant and animal fossils from the Whidbey Formation represent two environments. An upper sand unit contains predominantly terrestrial molluscs (4 taxa), insects, and a vole (cf. Phenacomys), whereas a lower clay unit contains ostracodes (9 taxa), freshwater molluscs (6 taxa), insects (9 taxa), freshwater plant seeds (6 taxa), and fish (cf. Gasterosteus : stickleback). These taxa are compatible with interglacial climatic conditions on a coastal plain environment. The inferred freshwater and terrestrial environments of the Whidbey Formation imply local tectonic subsidence of the regional since the last interglaciation.

  15. Quaternary paleoceanography of the deep Arctic Ocean based on quantitative analysis of Ostracoda

    USGS Publications Warehouse

    Cronin, T. M.; Holtz, T.R., Jr.; Whatley, R.C.

    1994-01-01

    Ostracodes were studied from deep Arctic Ocean cores obtained during the Arctic 91 expedition of the Polarstern to the Nansen, Amundsen and Makarov Basins, the Lomonosov Ridge, Morris Jesup Rise and Yermak Plateau, in order to investigate their distribution in Arctic Ocean deep water (AODW) and apply these data to paleoceanographic reconstruction of bottom water masses during the Quaternary. Analyses of coretop assemblages from Arctic 91 boxcores indicate the following: ostracodes are common at all depths between 1000 and 4500 m, and species distribution is strongly influenced by water mass characteristics and bathymetry; quantitative analyses comparing Eurasian and Canada Basin assemblages indicate that distinct assemblages inhabit regions east and west of the Lomonosov Ridge, a barrier especially important to species living in lower AODW; deep Eurasian Basin assemblages are more similar to those living in Greenland Sea deep water (GSDW) than those in Canada Basin deep water; two upper AODW assemblages were recognized throughout the Arctic Ocean, one living between 1000 and 1500 m, and the other, having high species diversity, at 1500-3000 m. Downcore quantitative analyses of species' abundances and the squared chord distance coefficient of similarity reveals a distinct series of abundance peaks in key indicator taxa interpreted to signify the following late Quaternary deep water history of the Eurasian Basin. During the Last Glacial Maximum (LGM), a GSDW/AODW assemblage, characteristic of cold, well oxygenated deep water > 3000 m today, inhabited the Lomonosov Ridge to depths as shallow as 1000 m, perhaps indicating the influence of GSDW at mid-depths in the central Arctic Ocean. During Termination 1, a period of high organic productivity associated with a strong inflowing warm North Atlantic layer occurred. During the mid-Holocene, several key faunal events indicate a period of warming and/or enhanced flow between the Canada and Eurasian Basins. A long

  16. Ocular shell structures in some Cretaceous trachyleberid Ostracoda

    USGS Publications Warehouse

    Kontrovitz, M.; Puckett, T.M.

    1998-01-01

    This is the first study of internal ocular shell structures of Cretaceous ostracodes. Internal molds from eight species of four genera from Santonian, Campanian, and Maastrichtian strata revealed a stalked ocular sinus constricted along its length and distally inflated. The latter part has anterior and posterior lobes and a subcentral concavity. These Cretaceous trachyleberids have ocular shell structures similar to Cenozoic taxa and it is presumed they functioned similarly. However, each taxon has a diagnostic ocular sinus and an inner surface of the eye tubercle that distinguishes each from all other forms examined.

  17. Species duration and extinction patterns in Cenozoic non-marine Ostracoda, Western United States

    NASA Astrophysics Data System (ADS)

    Swain, Frederick M.

    About 260 species of non-marine Ostracoda appeared and, for the most part, became extinct during the approximately 65 million years of the Cenozoic Era in the western United States. Lacustrine rock sequences containing the ostracode faunas in the Colorado Plateau and Great Basin total as much as 10.000 m. Important new appearances occurred in the early Paleocene, late Paleocene?-early Eocene, late Eocene-Oligocene?, late Oligocene?-early Miocene, and late? Pliocene Epochs. Major extinctions took place in the middle and late Eocene, late Miocene, and Pliocene and early Pleistocene Epochs.

  18. The life history and in vivo culture of Coelomomyces utahensis (Blastocladiomycetes).

    PubMed

    Whisler, Howard C; Karanja, Diana M Sabwa; Shemanchuk, Joseph A; Zebold, Stephen L; Romney, Steven V; Nielsen, Lewis T

    2009-01-01

    Coelomomyces utahensis is a fungal parasite of several genera of mosquitoes that inhabit rock-pools in southern Utah. Studies of the biology of Coelomomyces and their potential use in biological control of mosquitoes have been hindered by their complex life history, lack of axenic culture methods, and logistical problems producing their arthropod hosts for in vivo culture. In the case of C. utahensis, we have identified the alternate microcrustacean host as Potamocypris unicaudata, which is an ostracod that can be easily reared in abundance and stored for long periods. Described here are the life cycle and culturing of C. utahensis. PMID:18854194

  19. Cytherellid species (Ostracoda) and their significance to the Late Quaternary events in the Santos Basin, Brazil

    USGS Publications Warehouse

    Bergue, C.T.; Coimbra, J.C.; Cronin, T. M.

    2007-01-01

    Four autochthonous cytherellid species (Cytherella serratula (BRADY, 1880), C. hermargentina WHATLEY et al. 1998, C. pleistocenica sp. nov. and C. santosensis sp. nov.) have been identified from two offshore cores (44 samples) within the Santos Basin. The distribution of these ostracodes is controlled by local hydrological conditions such as the temperature and, possibly, the oxygen minimum zone (OMZ). However, these factors cannot explain completely the species occurrence in the analysed cores, and relative sea level changes and productivity variation driven by climatic changes are proposed as additional explanations for the faunal distribution pattern. ?? E. Schweizerbart'sche Verlagsbuchhandlung (Na??gele u. Obermiller), 2007.

  20. Kuznetsovia, a new generic replacement name for Aenigma Kuznetsova, 1957 (Ostracoda) non Newman, 1836 (Coleoptera).

    PubMed

    Doweld, Alexander B

    2016-01-01

    The generic name Aenigma was proposed by Kuznetsova (1957: 68; type species A. jucunda Kuznetsova, by original designation) for a new fossil ostracod genus from the Lower Cretaceous (Barremian) of Tegchaj, North-Eastern Azerbaijan, former USSR (Transcaucasia). However, this name is already preoccupied by a marine gastropod molluscan generic name Aenigma Newman (1836: 499), which is in active current use in zoology (Coleoptera: Carabidae). Besides this earliest generic name, a few homonyms were also known: Aenigma Amsel (1956: 288) [Lepidoptera], Aenigma Koch (in Martin & Chemnitz 1846: 1, unpaginated) [Mollusca], Aenigma Karsch (1878: 825) [Arachnida], Aenigma Strecker (1876: 122) [Lepidoptera]. PMID:27395148

  1. Oligocene to mid-Pliocene deep sea Ostracoda from the South Pacific Gyre and their paleoceanographic significance

    NASA Astrophysics Data System (ADS)

    Alvarez Zarikian, C. A.; Wade, B. S.; Villarejo, J.; Firth, J. V.

    2012-12-01

    We report on the taxonomic, biostratigraphical and paleoceanographic significance of early Paleocene, Oligocene, and middle Miocene to middle Pliocene ostracod faunas from IODP Sites U1367, U1368 and U1370. Sites U1367 (4289 m water depth) and U1368 (3740 water depth) are located near the center of the South Pacific Gyre (SPG) along ~26° S latitude, whereas Site U1370 (5074 m water depth) is located in the southwestern region of the SPG at 41° S latitude. The SPG is the largest of the ocean gyres, its center farther from continents and productive ocean regions than the center of any other gyre, and is considered Earth's largest oceanic desert. According to the magnetic sea floor lineations the crustal age has been estimated to be between 33.3 and 33.7 Ma at Site U1367, between 13.4 and 13.6 Ma at U1368, and between 73.6 and 79.5 Ma at U1370. Carbonate ooze are the dominant lithology at Sites U1367 and U1368, whereas at Site U1370 carbonate ooze was present only within a short (<2 m) interval near the base of the cored sequence. Planktonic foraminifer and calcareous nannofossil biostratigraphy established that the carbonate ooze at U1367 extends from ~33.7 Ma to ~26 Ma; at U1368 from ~13 Ma to ~1.9 Ma; and the short carbonate sequence at U1370 is 64 My old. The Oligocene ostracod assemblage consists of a relatively diverse fauna characterized by higher occurrences of Krithe, Poseidonamicus, Argilloecia and Cytheropteron, and suggests increased food supply to the ocean floor during the early Oligocene. The mid-Miocene to mid-Pliocene ostracod assemblage is comparatively less diverse and dominated by Krithe, Poseidonamicus, Henryhowella and Bradleya suggesting more oligotrophic conditions and a fauna more adapted to the corrosive bottom waters. Only one specimen of Marwickcythereis was found in a Paleocene sample at U1370. Preservation of ostracods and their stratigraphic variability are affected by the position of each site with respect to the lysocline and the

  2. Pliocene palaeotemperature reconstruction for the southern North Sea Based on Ostracoda

    NASA Astrophysics Data System (ADS)

    Wood, A. M.; Whatley, R. C.; Cronin, T. M.; Holtz, T.

    The development of a large northeastern Atlantic shelf ostracod database has confirmed that an intrinsic relationship exists between watermass temperature and the spatial (latitudinal) distribution of benthonic shelf Ostracoda. A second Pliocene ostracod database, using assemblages from four boreholes in The Netherlands and a number of localities from the East Anglian Neogene succession has also been constructed. A quantitative method of modern analogues and the Squared Chord Distance dissimilarity coefficient has been employed as a means of calculating the level of similarity between Recent and Neogene assemblages and, therefore, to aid in the reconstruction of palaeotemperatures in the southern North Sea Basin during the Pliocene. The results, in the form of contoured dissimilarity values, indicate the presence of at least seven palaeoceanographical climatic phases between ca. 5.2 and 1.6 Ma BP. An early Pliocene cooling phase (ecozone A), in which the fauna is dominated by the cryophilic species; Palmenella limicola (Norman), Elofsonella concinna (Jones), Robertsonites tuberculatus (Sars), Neomonoceratina tsurugasakensis (Tabuki) and Acanthocythereis dunelmensis (Norman), supervenes a period of stable subtropical conditions in the Miocene. A 'mid' Pliocene warming phase (ecozone B), which has been documented throughout the North Atlantic, can be recognized in the faunal composition of the sublittoral ostracod assemblages of both The Netherlands and East Anglia. A hiatus between the Coralline and Waltonian crags is thought to be associated with a deterioration in climatic conditions. Recent analogues to The Netherlands faunas of ecozone C (first phase late Pliocene cooling, ca. 2.9 Ma BP) indicate a decrease of approximately 5-6°C in mean summer surface temperatures. A return to elevated temperatures, of a Mauritanian aspect, can be seen in the fauna of the FA2 zone and Waltonian Crag. This amelioration of climate occurred prior to the Praetiglian cold phase

  3. Did the Mississippian Lodgepole buildup at Dickinson Field (North Dakota) form as a gas seep ({open_quotes}vent{close_quotes}) community?

    SciTech Connect

    Longman, M.W.

    1996-10-01

    The Lower Mississippian Lodgepole carbonate buildup reservoir at Dickinson Field in Stark County, North Dakota, has been widely reported as being a Waulsortian (or Waulsortian-like) mound. The term {open_quotes}Waulsortian mound{close_quotes} is used for a variety of Early Mississippian carbonate buildups that share a number of features including an abundance of carbonate mud, a {open_quotes}framework{close_quotes} of organisms such as fenestrate bryozoans and crinoids that tended to trap or baffle sediment, and a general absence of marine-cemented reef framework. Although the age of the Lodgepole mound at Dickinson Field qualifies it to be a Waulsortian mound, petrographic study of cores reveals that the reservoir rocks are quite unlike those in true Waulsortian mounds. Instead of being dominated by carbonate mud, the Lodgepole mound core is dominated by marine cement. Furthermore, ostracods and microbial limestones are common in the mound core where they occur with crinoid debris and small amounts of bryozoan, coral, and brachiopod debris. The abundant microbial limestones and marine cement indicate that the Dickinson mound formed as a lithified reef on the sea floor rather than as a Waulsortian mud mound. The microbial limestones, marine cement, and common ostracods in the mount core, and the fact that the mound nucleated almost directly o top of the Bakken Shale, suggest that the Dickinson Lodgepole mound formed at the site of a submarine spring and gas seep.

  4. Paleobiology of the Sand Beneath the Valders Diamicton at Valders, Wisconsin

    NASA Astrophysics Data System (ADS)

    Maher, Louis J.; Miller, Norton G.; Baker, Richard G.; Curry, B. Brandon; Mickelson, David M.

    1998-03-01

    Previously undescribed pollen, plant macrofossils, molluscs, and ostracodes were recovered from a 2.5-m-thick glaciolacustrine unit of silty sand and clay at Valders, Wisconsin. The interstadial sediment was deposited about 12,200 14C yr B.P. after retreat of the Green Bay lobe that deposited diamicton of the Horicon Formation, and before advance of the Lake Michigan lobe that deposited the red-brown diamicton of the Valders Member of the Kewaunee Formation. Fluctuations of abundance of Candona subtriangulata, Cytherissa lacustris,and three other species define four ostracode biozones in the lower 1.7 m, suggesting an open lake environment that oscillated in depth and proximity to glacial ice. Pollen is dominated by Piceaand Artemisia,but the low percentages of many other types of long-distance origin suggest that the terrestrial vegetation was open and far from the forest border. The upper part of the sediment, a massive sand deposited in either a shallow pond or a sluggish stream, contains a local concentration of plant macrofossils. The interpretation of a cold open environment is supported by the plant macrofossils of more than 20 species, dominated by those of open mineral soils ( Arenaria rubella, Cerastium alpinumtype, Silene acaulis, Sibbaldia procumbens, Dryas integrifolia, Vaccinium uliginosumvar. alpinum, Armeria maritima,etc.) that in North America occur largely in the tundra and open tundra-forest ecotone of northern Canada. Ice-wedge casts occur in the sand.

  5. Change and recovery of coastal mesozooplankton community structure during the Deepwater Horizon oil spill

    NASA Astrophysics Data System (ADS)

    Carassou, L.; Hernandez, F. J.; Graham, W. M.

    2014-12-01

    The response of mesozooplankton community structure to the Deepwater Horizon oil spill in the northern Gulf of Mexico was investigated using data from a long-term plankton survey off the coast of Alabama (USA). Environmental conditions observed in the study area during the oil spill (2010) were compared to historical observations (2005-2009), to support the contention that variations observed in zooplankton assemblage structure may be attributed to the oil spill, as opposed to natural climatic or environmental variations. Zooplankton assemblage structure observed during the oil spill period (May-August) in 2010 was then compared to historical observations from the same period (2005-2009). Significant variations were detected in assemblage structure in May and June 2010, but these changes were no longer significant by July 2010. The density of ostracods, cladocerans and echinoderm larvae were responsible for most of the differences observed, but patterns differed depending on taxa and months. Many taxa had higher densities during the oil spill year, including calanoid and cyclopoid copepods, ostracods, bivalve larvae and cladocerans, among others. Although this result is somewhat surprising, it is possible that increased microbial activity related to the infusion of oil carbon may have stimulated secondary production through microbial-zooplankton trophic linkages. Overall, results suggest that, although changes in zooplankton community composition were observed during the oil spill, variations were weak and recovery was rapid.

  6. Microfossils, a Key to Unravel Cold-Water Carbonate Mound Evolution through Time: Evidence from the Eastern Alboran Sea

    PubMed Central

    Stalder, Claudio; Vertino, Agostina; Rosso, Antonietta; Rüggeberg, Andres; Pirkenseer, Claudius; Spangenberg, Jorge E.; Spezzaferri, Silvia; Camozzi, Osvaldo; Rappo, Sacha; Hajdas, Irka

    2015-01-01

    Cold-water coral (CWC) ecosystems occur worldwide and play a major role in the ocean's carbonate budget and atmospheric CO2 balance since the Danian (~65 m.y. ago). However their temporal and spatial evolution against climatic and oceanographic variability is still unclear. For the first time, we combine the main macrofaunal components of a sediment core from a CWC mound of the Melilla Mounds Field in the Eastern Alboran Sea with the associated microfauna and we highlight the importance of foraminifera and ostracods as indicators of CWC mound evolution in the paleorecord. Abundances of macrofauna along the core reveal alternating periods dominated by distinct CWC taxa (mostly Lophelia pertusa, Madrepora oculata) that correspond to major shifts in foraminiferal and ostracod assemblages. The period dominated by M. oculata coincides with a period characterized by increased export of refractory organic matter to the seafloor and rather unstable oceanographic conditions at the benthic boundary layer with periodically decreased water energy and oxygenation, variable bottom water temperature/density and increased sediment flow. The microfaunal and geochemical data strongly suggest that M. oculata and in particular Dendrophylliidae show a higher tolerance to environmental changes than L. pertusa. Finally, we show evidence for sustained CWC growth during the Alleröd-Younger-Dryas in the Eastern Alboran Sea and that this period corresponds to stable benthic conditions with cold/dense and well oxygenated bottom waters, high fluxes of labile organic matter and relatively strong bottom currents PMID:26447699

  7. A multi-proxy palaeoecological and palaeoclimatic record within full glacial lacustrine deposits, western Tennessee, USA

    USGS Publications Warehouse

    Grimley, D.A.; Daniel, L.; Kaplan, S.W.; Yansa, C.H.; Curry, B. Brandon; Oches, E.A.

    2009-01-01

    The Fulton Section, along the Mississippi River in western Tennessee, USA, is a 1km continuous exposure (~20m vertically) of Quaternary fluvial and lacustrine deposits, inset within Eocene sediments and buried by thick loess. Fossiliferous slackwater lake sediments record maximum aggradation during the last two major glaciations, with deposition between ca. 190-140 ka and 24-1814C ka BP, based on amino acid and radiocarbon chronology, respectively. During the onset of full glacial conditions (ca. 24-22 14C ka BP), a relatively permanent shallow lake environment is indicated by ostracods, aquatic molluscs, and both pollen and macrofossils of aquatic plants. By 21.8 14C ka BP, increasing emergent plants, amphibious gastropods (Pomatiopsis) and heavier ??18O compositions suggest marsh-like conditions in a periodically drying lake. The surrounding uplands consisted of Picea-Pinus woodlands mixed with cool-temperate hardwoods (e.g. Quercus, Populus, Carya), grasses and herbs. More open conditions ensued ca. 20 14C ka BP, with loess and slopewash gradually infilling the former lake by 18 14C ka BP. Modern analogue analyses of ostracods and palaeontological evidence imply a full glacial climate similar to today's mixed-boreal zone in central Minnesota, USA, about 98C cooler in mean annual temperature than present-day western Tennessee. Copyright ?? 2009 John Wiley & Sons, Ltd.

  8. Paleo-environmental interpretation of Paleocene Sepultura Formation in type locality, Mesa La sepultura, Baja California, Mexico

    SciTech Connect

    Arzate-Hernandez, L.; Tellezduarte, M.

    1988-03-01

    The Sepultura Formation in its type locality consists of two major lithostratigraphic units. The basal A unit overlies the Cretaceous Rosario Formation. It consists predominantly of fine-grained, poorly consolidated sandstones; some conglomerates; and thin beds of well-consolidated lenticular fossiliferous sandstones, which show some cyclic sedimentation. The poorly consolidated sandstones contain glauconitic layers; abundant shark teeth, benthic forams, and ostracods; and sparse mollusks, brachiopods, and Ophiomorpha-like trace fossils. These faunas indicate deposition in nearshore shallow waters. The interbedded consolidated lenticular sandstones probably indicate storm-induced deposition below wave base. This mechanism is assumed to be responsible for the high concentration of fossils consisting predominantly of unworn molluscan shells, scaphopods, echinoid spines, corals, and forams. In places, the elongated shells of Turritella pachecoensis show a preferential orientation to the southwest. At the top of the unit, a poorly fossiliferous red conglomerate indicates deltaic conditions. Overlying the conglomerate is unit B which shows a change in the sedimentary environment. It consists of a calcareous shallowing upward sequence of nodular to massive algal limestone with caliche at top. The microfossils of this unit show glauconitization in places, and consist, in addition to algal fragments, of forams, microscopic mollusks, and some ostracods and calcispherules from shallow waters (less than 30 m deep).

  9. Stratigraphy and facies development of the marine Late Devonian near the Boulongour Reservoir, northwest Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Suttner, Thomas J.; Kido, Erika; Chen, Xiuqin; Mawson, Ruth; Waters, Johnny A.; Frýda, Jiří; Mathieson, David; Molloy, Peter D.; Pickett, John; Webster, Gary D.; Frýdová, Barbora

    2014-02-01

    Late Devonian to Early Carboniferous stratigraphic units within the 'Zhulumute' Formation, Hongguleleng Formation (stratotype), 'Hebukehe' Formation and the Heishantou Formation near the Boulongour Reservoir in northwestern Xinjiang are fossil-rich. The Hongguleleng and 'Hebukehe' formations are biostratigraphically well constrained by microfossils from the latest Frasnian linguiformis to mid-Famennian trachytera conodont biozones. The Hongguleleng Formation (96.8 m) is characterized by bioclastic argillaceous limestones and marls (the dominant facies) intercalated with green spiculitic calcareous shales. It yields abundant and highly diverse faunas of bryozoans, brachiopods and crinoids with subordinate solitary rugose corals, ostracods, trilobites, conodonts and other fish teeth. The succeeding 'Hebukehe' Formation (95.7 m) consists of siltstones, mudstones, arenites and intervals of bioclastic limestone (e.g. 'Blastoid Hill') and cherts with radiolarians. A diverse ichnofauna, phacopid trilobites, echinoderms (crinoids and blastoids) together with brachiopods, ostracods, bryozoans and rare cephalopods have been collected from this interval. Analysis of geochemical data, microfacies and especially the distribution of marine organisms, which are not described in detail here, but used for facies analysis, indicate a deepening of the depositional environment at the Boulongour Reservoir section. Results presented here concern mainly the sedimentological and stratigraphical context of the investigated section. Additionally, one Late Devonian palaeo-oceanic and biotic event, the Upper Kellwasser Event is recognized near the section base.

  10. Upper Cretaceous (Maastrichtian) Charophyte Gyrogonites from the Lameta Formation of Jabalpur, Central India: Palaeobiogeographic and Palaeoecological Implications

    NASA Astrophysics Data System (ADS)

    Khosla, Ashu

    2014-12-01

    A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. he Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.