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. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  11. 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

  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. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  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. 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

  3. 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

  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. 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.

  6. 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.

  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. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  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. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  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. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  6. 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.

  7. 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.

  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. 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

  15. 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

  16. 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

  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. 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.

  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. 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

  7. 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.

  8. 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

  9. 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.

  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. 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.

  12. 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.

  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. 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.

  15. 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.

  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. 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

  18. 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

  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. 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.

  6. 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.

  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. 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

  1. 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

  2. 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.

  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 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

  12. 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

  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. 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

  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. 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).

  20. 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

  1. 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

  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. 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

  8. 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

  9. 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.

  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. 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.

  14. 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.

  15. 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

  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 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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

  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. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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

  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. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  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. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  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. 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.

  10. 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

  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. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  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. 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

  2. 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.

  3. Experimental evaluation of Candonocypris novaezelandiae (Crustacea: Ostracoda) in the biocontrol of Schistosomiasis mansoni transmission

    PubMed Central

    Yousif, Fouad; Hafez, Sherif; El Bardicy, Samia; Tadros, Menerva; Taleb, Hoda Abu

    2013-01-01

    Objective To test Candonocypris novaezelandiae (Baird) (C. novaezelandiae), sub-class Ostracoda, obtained from the Nile, Egypt for its predatory activity on snail, Biomphalaria alexandrina (B. alexandrina), intermediate host of Schistosoma mansoni (S. mansoni) and on the free-living larval stages of this parasite (miracidia and cercariae). Methods The predatory activity of C. novaezelandiae was determined on B. alexandrina snail (several densities of eggs, newly hatched and juveniles). This activity was also determined on S. mansoni miracidia and cercariae using different volumes of water and different numbers of larvae. C. novaezelandiae was also tested for its effect on infection of snails and on the cercarial production. Results C. novaezelandiae was found to feed on the eggs, newly hatched and juvenile snails, but with significant reduction in the consumption in the presence of other diet like the blue green algae (Nostoc muscorum). This ostracod also showed considerable predatory activity on the free-living larval stages of S. mansoni which was affected by certain environmental factors such as volume of water, density of C. novaezelandiae and number of larvae of the parasite. Conclusions The presence of this ostracod in the aquatic habitat led to significant reduction of snail population, infection rate of snails with schistosme miracidia as well as of cercarial production from the infected snails. This may suggest that introducing C. novaezelandiae into the habitat at schistosome risky sites could suppress the transmission of the disease. PMID:23620849

  4. Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil)

    PubMed Central

    Gross, Martin; Piller, Werner E.; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

    2011-01-01

    In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ18O and δ13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene. PMID:26523089

  5. Late Quaternary Spring-Fed Deposits of the Grand Canyon and Their Implication for Deep Lava-Dammed Lakes

    NASA Astrophysics Data System (ADS)

    Kaufman, Darrell S.; O'Brien, Gary; Mead, Jim I.; Bright, Jordon; Umhoefer, Paul

    2002-11-01

    One of the most intriguing episodes in the Quaternary evolution of the Grand Canyon of the Colorado River, Arizona, was the development of vast lakes that are thought to have backed up behind lava erupted into the gorge. Stratigraphic evidence for these deep lava-dammed lakes is expectedly sparse. Possible lacustrine deposits at six areas in the eastern canyon yielded no compelling evidence for sediment deposited in a deep lake. At two of the sites the sediment was associated with late Quaternary spring-fed pools and marshes. Water-lain silt and sand at lower Havasu Creek was deposited ˜3000 cal yr ago. The deposit contains an ostracode assemblage similar to that living in the modern travertine-dammed pools adjacent to the outcrop. The second deposit, at Lees Ferry, formed in a spring-fed marsh ˜43,000 cal yr ago, as determined by 14C and amino acid geochronology. It contains abundant ostracode and mollusk fossils, the richest assemblages reported from the Grand Canyon to date. Our interpretation of these sediments as spring-fed deposits, and their relative youth, provides an alternative to the conventional view that deposits like these were formed in deep lava-dammed lakes that filled the Grand Canyon.

  6. Microcrustacea in flowing water - experimental-analysis of washout times and a field-test

    USGS Publications Warehouse

    Richardson, W.B.

    1992-01-01

    1. Flow-chamber experiments were conducted to evaluate the ability of microcrustacea to maintain position in moving water. These results were compared to distributions of zooplankton and water velocity in a stream pool to determine the relationship of animal density to water movement and swimming ability.^2. Cladocerans exhibited negative rheotaxis (directed behaviour against a current) but poor ability to maintain position at velocities >2.5 Cm s-1. Daphnia and scapholeberis were better at avoiding washout than moina and diaphanosoma. At velocities 2.5 Cm s-1, scapholeberis >3.2 Cm s-1 and eucyclops >7.75 Cm s-1. Washout time of daphnia and scapholeberis was positively related to body size and negatively to water velocity and possession of eggs. Washout was inversely related to water velocity for eucyclops.^4. Highest densities of microcrustacea in a stream pool were found in non-flowing or downstream zones of the pool. Benthic (hydracarina, harpacticoid copepods, ostracods) and fast-swimming (cyclopoids) forms were most common in flowing zones. Facultatively benthic cladocera were abundant in regions of no flow. Rotifers and immature copepods were most abundant at the downstream end of the pool.^5. Behavioural mechanisms for remaining in stream pools at times of high flow appear to include: (i) flow avoidance (simocephalus, chydorus, scapholeberis and cyclopoids), (ii) use of benthic habitat (ostracods, harpacticoids, hydracarina), (iii) strong swimming ability (cyclopoids).

  7. Environmental conditions of the Laptev Sea region in the late postglacial time

    NASA Astrophysics Data System (ADS)

    Naidina, O. D.

    2016-01-01

    The comparison between the first results of comprehensive micropaleontological analysis (pollen, spores, foraminifera, and ostracods) and those of radiocarbon dating (AMS14C) for the sediments of the eastern inner shelf of the Laptev Sea (the core collected from depth of 37 m) indicates that considerable changes in natural conditions in the sea and on land coincide in time and refer to the time period of 1500-1700 years B.P. This period is characterized by changes in microfossils: appearance of thermophilic pollen and planktonic foraminifera and increase in total number of benthic foraminifera and ostracods. Intense warming and humidification of the climate reconstructed for this 200-year period promoted the expansion of large-shrub tundra. Summer air temperatures were lower than that in the peak mid-Holocene climatic optimum by 2°-3°C, but 1°C higher than the present-day temperature. An estuary freshwater basin developed: it was strongly affected by river discharge, but North Atlantic waters also intensely penetrated here in short-term intervals. In general, the studied microfossil complex reflects the relatively stable environmental conditions and decrease in seawater salinity in the eastern part of the Laptev Sea shelf during the last 2300 years.

  8. Synimpact-postimpact transition inside Chesapeake Bay crater

    NASA Astrophysics Data System (ADS)

    Poag, C. Wylie

    2002-11-01

    The transition from synimpact to postimpact sedimentation inside Chesapeake Bay impact crater began with accumulation of fallout debris, the final synimpact deposit. Evi dence of a synimpact fallout layer at this site comes from the presence of unusual, millimeter- scale, pyrite microstructures at the top of the Exmore crater-fill breccia. The porous geometry of the pyrite microstructures indicates that they originally were part of a more extensive pyrite lattice that encompassed a layer of millimeter-scale glass microspherules—fallout melt particles produced by the bolide impact. Above this microspherule layer is the initial postimpact deposit, a laminated clay-silt-sand unit, 19 cm thick. This laminated unit is a dead zone, which contains abundant stratigraphically mixed and diagenetically altered or impact-altered microfossils (foraminifera, calcareous nannofossils, dinoflagellates, ostracodes), but no evidence of indigenous biota. By extrapolation of sediment- accumulation rates, I estimate that conditions unfavorable to microbiota persisted for as little as <1 k.y. to 10 k.y. after the bolide impact. Subsequently, an abrupt improvement of the late Eocene paleoenvironment allowed species-rich assemblages of foraminifera, ostracodes, dinoflagellates, radiolarians, and calcareous nannoplankton to quickly reoccupy the crater basin, as documented in the first sample of the Chickahominy Formation above the dead zone.

  9. Quaternary glacial and deglacial Ostracoda in the thermocline of the Little Bahama Bank (NW Atlantic): Palaeoceanographic implications

    USGS Publications Warehouse

    Rodriguez-Lazaro, J.; Cronin, T. M.

    1999-01-01

    We determined faunal and oceanographic changes during the last glacial and deglacial in the Providence Channel, Little Bahama Bank (LBB), using modern ocean (from LBB, Florida-Hatteras Slope and Blake Plateau, western North Atlantic) and late Quaternary (LBB) distributions of the benthic ostracode genus Krithe from the mid-depth (300-1600 m) subtropical North Atlantic Ocean. Nine species of Krithe are limited in their bathymetric distribution by warm bottom water temperatures (or a temperature-related parameter) in the thermocline of the modern Atlantic. During the last glacial interval in the northwest Providence Channel of the Little Bahama Bank five species of Krithe (K. aequabilis, K. dolichodeira, K. gr. minima, K. reversa and K. trinidadensis) migrated upslope; conversely, during the deglaciation, most Krithe species migrated downslope, re-occupying their deeper niches. These vertical species migrations are attributed to decreased glacial bottom water temperatures and perhaps increased dissolved oxygen during the last glacial and warmer water temperatures during the deglacial. Based upon thermal values of recent depth ranges of selected species of Krithe, we estimate that glacial waters cooled about 4??C (shallower than 900 m) and about 2??C (deeper than 900 m) and deglacial waters warmed about the same values in shallow and mid-depth water masses, comparing to modern temperatures. The discovery of common Halocypris, a mesopelagic ostracode, in Little Bahama Bank glacial and deglacial sediments also suggests greater oxygenation relative to the late Holocene.

  10. Paleoecology of the Niland Tongue

    SciTech Connect

    Robbins, E.I.

    1987-01-01

    The swamp or paludal ecosystem is preserved in coals and carbonaceous shales. Remains of organisms of the swamp communities consist of bacteria and fungi; algae; invertebrates such as pelecypods, gastropods, ostracodes, and insects; vertebrates such as a hard-shelled turtle and crocodiles; and vascular plant remains. Aquatic communities are found in dark shale and are represented by the remains of bacteria and fungi; algae; invertebrates such as pelecypods, gastropods, and insects; and vertebrates such as crocodiles, fish, and a soft-shelled turtle. No vascular macrophytes (rooted aquatic vegetation) could be identified in the pollen and spore assemblage. Charophytes are abundant and show that colonies of the aquatic alga lived on the lake bottoms. The great variety of organisms suggests that the environment had a high input of nutrients. The phosphate-rich Phosphoria Formation, which could serve as a good source of nutrients, cropped out in the watershed of the Niland Tongue basin. The ostracode-crocodile association, calcareous charophytes, and good preservation of plant tissues and palynomorphs put limits on the alkaline geochemical environment in which the lacustrine rocks were deposited. The palynomorphs in the Niland Tongue rocks are dark yellow and light brown in color. These colors suggest that rocks containing them have been buried deeper in the past than they are today.

  11. Positive correspondence between the completeness of Late Quaternary fossiliferous lacustrine successions in Illinois and the basin index

    SciTech Connect

    Curry, B.B. )

    1994-04-01

    The basin index, defined as the ratio of the maximum area of a paleolake versus the area of the catchment (A[sub L]/A[sub C]), initially was used to compare the moisture balance of pluvial lakes in closed and semi-closed basins under arid climates. In this study the basin index also corresponds to the completeness of ostracode and pollen successions preserved in the basins. The basin indices of four breached kettles located in south-central Illinois as well as the thickness of fossiliferous zones determined from cores are compared. Collectively, the basins contain ostracode and pollen records spanning from the late Illinoian ([approx] 150 ka) to the Holocene. Hopwood Farm has the smallest index (0.03) and has a fossil record that terminates in Sangamonian clay. The fossil succession at Bald Knob Basin, with an intermediate basin index of 0.4, contains several lacuna in post-Sangamonian sediment and poorly preserved pollen in Holocene material. Raymond and Pittsburg Basins have indices > 1.0 and contain the most complete fossil records. The data indicate that the basin index is a useful guide for choosing sites with the greatest potential for yielding cores with conformable sediment successions.

  12. The origin and disappearance of the late Pleistocene-early Holocene short-lived coastal wetlands along the Carmel coast, Israel

    NASA Astrophysics Data System (ADS)

    Sivan, Dorit; Greenbaum, Noam; Cohen-Seffer, Ronit; Sisma-Ventura, Guy; Almogi-Labin, Ahuva

    The formation of short-lived backswamps along the Carmel coast of Israel coincides with the rapid global sea-level rise during the late Pleistocene-early Holocene transition. The current study shows that the wetland phenomena originated around 10,000 yr ago and dried up shortly before the local Pre-Pottery Neolithic humans settled on the wetland dark clay sediments 9430 cal yr BP. Palaeontological and stable-isotope data were used in this study to elucidate previously published sedimentological reconstruction obtained from a core drilled into the western trough of the Carmel coastal plain. The water body contained typical brackish calcareous fauna, with variable numerical abundance and low species richness of ostracods and foraminifera. The δ 18O and δ 13C of the ostracod Cyprideis torosa show close similarity to the present Pleistocene coastal aquifer isotopic values. This study therefore concludes that the wetlands were shallow-water bodies fed by groundwater, with no evidence of sea-water mixing. It seems that they developed as the result of high groundwater levels, transportation of sediments landward, and deposition of sand bars at the paleo-river mouths. It is still not fully understood why these wetlands deteriorated abruptly and disappeared within less than 1000 yr.

  13. How is a giant sperm ejaculated? Anatomy and function of the sperm pump, or "Zenker organ," in Pseudocandona marchica (Crustacea, Ostracoda, Candonidae)

    NASA Astrophysics Data System (ADS)

    Yamada, Shinnosuke; Matzke-Karasz, Renate

    2012-07-01

    `Giant sperm', in terms of exceptionally long spermatozoa, occur in a variety of taxa in the animal kingdom, predominantly in arthropod groups, but also in flatworms, mollusks, and others. In some freshwater ostracods (Cypridoidea), filamentous sperm cells reach up to ten times the animal's body length; nonetheless, during a single copulation several dozen sperm cells can be transferred to the female's seminal receptacle. This highly effective ejaculation has traditionally been credited to a chitinous-muscular structure within the seminal duct, which has been interpreted as a sperm pump. We investigated this organ, also known as the Zenker organ, of a cypridoid ostracod, Pseudocandona marchica, utilizing light and electron microscope techniques and produced a three-dimensional reconstruction based on serial semi-thin histological sections. This paper shows that numerous muscle fibers surround the central tube of the Zenker organ, running in parallel with the central tube and that a thin cellular layer underlies the muscular layer. A cellular inner tube exists inside the central tube. A chitinous-cellular structure at the entrance of the organ has been recognized as an ejaculatory valve. In male specimens during copulation, we confirmed a small hole derived from the passage of a single spermatozoon through the valve. The new data allowed for proposing a detailed course of operation of the Zenker organ during giant sperm ejaculation.

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

    PubMed

    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

  15. Living males of the ‘ancient asexual’ Darwinulidae (Ostracoda: Crustacea)

    PubMed Central

    Smith, Robin J; Kamiya, Takahiro; Horne, David J

    2006-01-01

    Three living male darwinulid ostracods of a new species of the genus Vestalenula have been found in Yakushima, Japan. This is the first report of living darwinulid males for over 100 years and their morphology casts doubt on the two previous records from the late 1800s. The presence of male darwinulids also calls into question the hypothesis that the family Darwinulidae is an exclusively ancient asexual group, reproducing without sex for over 200 million years (Myr). Male carapaces are of similar size and shape to A-1 juvenile females of the same species, suggesting that males may have been dismissed as A-1 juveniles in other living and fossil species. The antennae and fifth limbs are sexually dimorphic: the male antennae have six segments compared with five in the female and a series of putative chemical receptors originating at the extra segment boundary, while the male fifth limbs have well-developed grasping hooks, as in males of many ostracod groups. The lack of Zenker's Organ and of complex internal structures within the hemipenis contradicts previous hypotheses of the phylogenetic position of darwinulids. PMID:16777754

  16. Model for carbonate deposition in an Epicontinental Bay

    SciTech Connect

    Carney, C.; Smosna, R.

    1986-05-01

    By mapping the distribution of correlative sediments across the north-central region of the Appalachian basin, a paleogeographic model has been generated for part of the Mississippian period. During the Chesterian, the upper Greenbrier Limestone was deposited in an embayment that extended northward into parts of West Virginia, Ohio, Pennsylvanian, and Maryland. The bay, only a few hundred kilometers wide, was surrounded by lowlands to the west and north, and deltaic sediments shed from nearby highlands diluted the easternmost facies. In the bay, several different shallow-water carbonate environments are distinguished. Muddy skeletal sand was deposited in the central part, which was characterized by normal marine circulation and salinity. This open-bay facies supported a moderately diverse fauna of forams, brachiopods, and mollusks. From the central facies to the bay margins, water depth decreased, circulation became more restricted, and salinity was slightly higher. A restricted-bay facies developed closer to shore, with sediment consisting of pelletal mud and scattered skeletal grains. Diversity was lower, and the fauna was composed primarily of forams and ostracodes. A tidal mud flat surrounded the embayment on all three sides where partly to totally dolomitized mud containing cryptalgal structures formed. Oolite shoals, present on the eastern side of the bay near its mouth, mark areas where tidal currents were concentrated. Eventually, the epicontinental sea flooded the small enclosed bay, replacing the shallow-water facies with an open-marine facies. The new environment supported a highly diverse fauna including crinoids, brachiopods, mollusks, forams, and ostracods.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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).

  2. 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.

  3. 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.

  4. Influence of agriculture on aquatic invertebrate communities of temporary wetlands in the Prairie Pothole Region of North Dakota, USA

    USGS Publications Warehouse

    Euliss, N.H., Jr.; Mushet, D.M.

    1999-01-01

    We evaluated the influence of intensive agriculture on invertebrate communities of temporary wetlands as indicated by aquatic invertebrate resting eggs, shells, and cases remaining after wetlands dried. To facilitate the comparison, we sampled 19 wetlands within cropland areas and 19 wetlands within grassland areas. We found resting eggs, shells, and cases of significantly more taxa and greater numbers of cladoceran resting eggs (ephippia), planorbid and physid snail shells, and ostracod shells in wetlands within grasslands than in croplands. We also successfully incubated greater numbers of cladocerans and ostracods from soil samples collected from grassland sites. We were unable to detect differences in the viability of cladoceran ephippia between grassland and cropland wetlands, but our sample size was small due to an absence of ephippia in most cropland wetlands sampled; 74% of the cropland wetlands were devoid of cladoceran ephippia whereas ephippia were well represented in nearly all of our grassland sites. Our results corroborate findings of other investigators that prairie pothole wetlands have been negatively impacted by human activities. Our study demonstrates that aquatic invertebrates of temporary wetlands have been negatively impacted by intensive agriculture and suggests that future studies need to assess the influence of agricultural practices on wetland-dependant wildlife.

  5. Stratigraphy and paleoceanography of Pliocene deposits of Karaginsky Island, eastern Kamchatka, U.S.S.R.

    USGS Publications Warehouse

    Gladenkov, Yu. B.; Barinov, K.B.; Basilian, A.E.; Cronin, T. M.

    1991-01-01

    The lithology and paleontology of Pliocene deposits from Karaginsky Island, off eastern Kamchatka Peninsula, U.S.S.R., are described in order to provide a paleoceanographic reconstruction of this region of the eastern North Pacific Ocean. The stratigraphic sequence is divided into three suites - the Limimtevayamian, the Ust-Limimtevayamian, and the Tusatuvayamian, which correspond to three standard Pacific diatom zones - the Thalassiosira oestrupii, Neodenticula koizumi-N. kamtschatica, and N. koizumi. The entire sequence is further subdivided into six members and 18 distinct beds on the basis of molluscan assemblages and three members and seven beds on the basis of benthic foraminiferal assemblages. Marine ostracodes are described from the Limimtevayamian suite. The marine invertebrate assemblages from Karaginsky Island provide evidence that: (1) ocean water temperatures were warmer than today about 4 Ma and again about 3.5-3.0 Ma; (2) several Arctic-Atlantic species of molluscs and ostracodes migrated to the eastern North Pacific between 4.2-3.0 Ma, presumably through the proto-Bering Strait; (3) many species found in the Karaginsky Island Pliocene represent Pacific taxa which migrated through the Arctic into the North Atlantic during the late Pliocene. ?? 1991.

  6. Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil)

    NASA Astrophysics Data System (ADS)

    Gross, Martin; Piller, Werner E.; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

    2011-08-01

    In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ18O and δ13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene.

  7. Vegetation changes during the last deglacial and early Holocene: a record from Little Salt Spring Florida

    NASA Astrophysics Data System (ADS)

    Bernhardt, C. E.; Willard, D. A.; Landacre, B.; Gifford, J.

    2010-12-01

    We present a high-resolution, 7000 year long pollen record of vegetation change that spans the Younger Dryas and Early Holocene. An 8.2 m sediment core was collected from Little Salt Spring (LSS), FL, which is an hourglass-shaped karst sinkhole lake with a water depth of 72 m. Previous paleohydrological reconstructions based on carbon and oxygen isotopes indicate that LSS is sensitive to past deglacial climate and sea-level changes. Distinct changes in pollen assemblages from the LSS core correspond to well-documented climatic events. For example, cooler climate during the Younger Dryas is characterized by an abrupt increase in Carya pollen. This change in pollen assemblages corresponds to estimates of cooler temperatures from ostracode isotopic records from LSS. In addition, precipitation and temperature in the early Holocene is relatively invariate as reflected in the development of a comparatively stable bayhead hammock plant community. In general, the vegetation response at LSS indicates an abrupt onset of a cooler Younger Dryas followed by, based ostracode isotopic records, a warmer and a relatively stable Early Holocene. The LSS record has potential to examine human response to abrupt climate variability because recent archeological finds indicate Early Native Americans were present there at least 10,000 years ago.

  8. 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.

  9. Evidence for stagnation of the Harvard sublobe (Lake Michigan lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and subsequent tundra-like ice-marginal paleoenvironments from 17 600 to 15 700 BP

    USGS Publications Warehouse

    Curry, B. Brandon; Yansa, C.H.

    2004-01-01

    Glacial deposits of the last glaciation associated with the Harvard sublobe (Lake Michigan lobe) in northeastern Illinois, U.S.A., occur between sediment with dateable organics. The lower organics include fragments of Picea sp. as young as 24 000 ?? 270 BP. The supraglacial organics occur sparsely in laminated silt and fine sand in landforms that are positioned relatively high on the landscape, such as deposits from ice-walled lakes. These terrestrial organics yield ages that are 2500 to 1300 14C years older than organics at the base of sediment successions in nearby kettle basins. Basal 14C ages from four upland sites range from 17 610 ?? 270 to 16 120 ?? 80 BP. Our revised time-distance diagram of the Harvard sublobe now reflects a period of stagnation from 24 000 to about 17 600 BP. The supraglacial lacustrine silt yielded plant macrofossil assemblages of primarily tundra plants, including Salix herbacea and Dryas integrifolia. These plants likely grew in supraglacial and ice-marginal environments. The ostracode fauna include Cytherissa lacustris and Limnocythere friabilis. Geomorphic relations and ostracode ecology indicate that more than 17 m of ice buttressed some of the supraglacial lakes.

  10. Occurrence and food habits of the round goby in the profundal zone of southwestern Lake Ontario

    USGS Publications Warehouse

    Walsh, M.G.; Dittman, D.E.; O'Gorman, R.

    2007-01-01

    Little is known about the ecology of round goby (Neogobius melanostomus), an invasive benthic fish, in the profundal zone of the Great Lakes. In April 2002–2005 we caught increasing numbers of round gobies with a bottom trawl in the 45–150 m depth range of southwestern Lake Ontario. In 2005, we examined gut contents of 30 round gobies from each of three depths, 55, 95, and 130 m, and qualitatively compared gut contents with density of benthic invertebrates determined by Ponar grabs. Round goby guts contained mostly Dreissena spp. and opposum shrimp, Mysis relicta (Mysis); the frequency of occurrence of dreissenids in guts decreased with depth, whereas the frequency of occurrence of Mysis in guts increased with depth. Abundance of these invertebrates in the environment followed the same pattern, although dreissenids of optimum edible size (3–12 mm) were still abundant (1,373/m2) at 130 m, where round gobies primarily consumed Mysis, suggesting that round gobies may switch from dreissenids to more profitable prey when it is available. Other food items were ostracods and fish, with ostracods generally eaten by smaller round gobies and fish eaten by larger round gobies. Occurrence and increasing abundance of round gobies in the profundal zone and predation on Mysis by round goby could have far-reaching consequences for the Lake Ontario fish community.

  11. Abrupt climate change and collapse of deep-sea ecosystems

    USGS Publications Warehouse

    Yasuhara, Moriaki; Cronin, T. M.; Demenocal, P.B.; Okahashi, H.; Linsley, B.K.

    2008-01-01

    We investigated the deep-sea fossil record of benthic ostracodes during periods of rapid climate and oceanographic change over the past 20,000 years in a core from intermediate depth in the northwestern Atlantic. Results show that deep-sea benthic community "collapses" occur with faunal turnover of up to 50% during major climatically driven oceanographic changes. Species diversity as measured by the Shannon-Wiener index falls from 3 to as low as 1.6 during these events. Major disruptions in the benthic communities commenced with Heinrich Event 1, the Inter-Aller??d Cold Period (IACP: 13.1 ka), the Younger Dryas (YD: 12.9-11.5 ka), and several Holocene Bond events when changes in deep-water circulation occurred. The largest collapse is associated with the YD/IACP and is characterized by an abrupt two-step decrease in both the upper North Atlantic Deep Water assemblage and species diversity at 13.1 ka and at 12.2 ka. The ostracode fauna at this site did not fully recover until ???8 ka, with the establishment of Labrador Sea Water ventilation. Ecologically opportunistic slope species prospered during this community collapse. Other abrupt community collapses during the past 20 ka generally correspond to millennial climate events. These results indicate that deep-sea ecosystems are not immune to the effects of rapid climate changes occurring over centuries or less. ?? 2008 by The National Academy of Sciences of the USA.

  12. Stratigraphy and paleoceanography of Pliocene deposits of Karaginsky Island, eastern Kamchatka, U.S.S.R.

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yu. B.; Barinov, K. B.; Basilian, A. E.; Cronin, T. M.

    The lithology and paleontology of Pliocene deposits from Karaginsky Island, off eastern Kamchatka Peninsula, U.S.S.R., are described in order to provide a paleoceanographic reconstruction of this region of the eastern North Pacific Ocean. The stratigraphic sequence is divided into three suites — the Limimtevayamian, the Ust-Limimtevayamian, and the Tusatuvayamian, which correspond to three standard Pacific diatom zones — the Thalassiosira oestrupii, Neodenticula koizumi-N. kamtschatica, and N. koizumi. The entire sequence is further subdivided into six members and 18 distinct beds on the basis of molluscan assemblages and three members and seven beds on the basis of benthic foraminiferal assemblages. Marine ostracodes are described from the Limimtevayamian suite. The marine invertebrate assemblages from Karaginsky Island provide evidence that: (1) ocean water temperatures were warmer than today about 4 Ma and again about 3.5-3.0 Ma; (2) several Arctic-Atlantic species of molluscs and ostracodes migrated to the eastern North Pacific between 4.2-3.0 Ma, presumably through the proto-Bering Strait; (3) many species found in the Karaginsky Island Pliocene represent Pacific taxa which migrated through the Arctic into the North Atlantic during the late Pliocene.

  13. Barnacle settlement and the adhesion of protein and diatom microfouling to xerogel films with varying surface energy and water wettability.

    PubMed

    Finlay, John A; Bennett, Stephanie M; Brewer, Lenora H; Sokolova, Anastasiya; Clay, Gemma; Gunari, Nikhil; Meyer, Anne E; Walker, Gilbert C; Wendt, Dean E; Callow, Maureen E; Callow, James A; Detty, Michael R

    2010-08-01

    Previous work has shown that organosilica-based xerogels have the potential to control biofouling. In this study, modifications of chemistry were investigated with respect to their resistance to marine slimes and to settlement of barnacle cyprids. Adhesion force measurements of bovine serum albumin (BSA)-coated atomic force microscopy (AFM) tips to xerogel surfaces prepared from aminopropylsilyl-, fluorocarbonsilyl-, and hydrocarbonsilyl-containing precursors, indicated that adhesion was significantly less on the xerogel surfaces in comparison to a poly(dimethylsiloxane) elastomer (PDMSE) standard. The strength of adhesion of BSA on the xerogels was highest on surfaces with the highest and the lowest critical surface tensions, gamma(C) and surface energies, gamma(S), and duplicated the 'Baier curve'. The attachment to and removal of cells of the diatom Navicula perminuta from a similar series of xerogel surfaces were examined. Initial attachment of cells was comparable on all of the xerogel surfaces, but the percentage removal of attached cells by hydrodynamic shear stress increased with gamma(C) and increased wettability as measured by the static water contact angle, theta(Ws), of the xerogel surfaces. The percentage removal of cells of Navicula was linearly correlated with both properties (R(2) = 0.74 for percentage removal as a function of theta(Ws) and R(2) = 0.69 for percentage removal as a function of gamma(C)). Several of the aminopropylsilyl-containing xerogels showed significantly greater removal of Navicula compared to a PDMSE standard. Cypris larvae of the barnacle B. amphitrite showed preferred settlement on hydrophilic/higher energy surfaces. Settlement was linearly correlated with theta(Ws) (R(2) = 0.84) and gamma(C) (R(2) = 0.84). Hydrophilic xerogels should prove useful as coatings for boats in regions where fouling is dominated by microfouling (protein and diatom slimes). PMID:20645195

  14. Instantaneous Flow Structures and Opportunities for Larval Settlement: Barnacle Larvae Swim to Settle

    PubMed Central

    Granhag, Lena M.; Jonsson, Per R.

    2016-01-01

    Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with suitable instantaneous flow properties. In flume flow we characterized the proportion of suitable time windows in a series of flow velocities with focus on the near-bed flow. The change in the proportion of potential settling windows with increasing free-stream velocities was compared to the proportion of temporary attachment of barnacle cypris larvae at different flow velocities. We found large instantaneous flow variations in the near-bed flow where cyprid attachment took place. The probability of temporary attachment in cyprids declined with local flow speed and this response was compatible with a settling window lasting at least 0.1 s with a maximum local flow speed of 1.9–2.4 cm s-1. Cyprids swam against the near-bed flow (negative rheotaxis) and the swimming speed (1.8 cm s-1) was close to the critical speed that permitted temporary attachment. We conclude that temporary attachment in barnacle cyprids requires upstream swimming to maintain a fixed position relative to the substrate for at least 0.1 s. This behaviour may explain the ability of barnacles to recruit to high-flow environments and give cyprids flexibility in the pre-settlement choice of substrates based on flow regime. PMID:27463968

  15. Instantaneous Flow Structures and Opportunities for Larval Settlement: Barnacle Larvae Swim to Settle.

    PubMed

    Larsson, Ann I; Granhag, Lena M; Jonsson, Per R

    2016-01-01

    Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with suitable instantaneous flow properties. In flume flow we characterized the proportion of suitable time windows in a series of flow velocities with focus on the near-bed flow. The change in the proportion of potential settling windows with increasing free-stream velocities was compared to the proportion of temporary attachment of barnacle cypris larvae at different flow velocities. We found large instantaneous flow variations in the near-bed flow where cyprid attachment took place. The probability of temporary attachment in cyprids declined with local flow speed and this response was compatible with a settling window lasting at least 0.1 s with a maximum local flow speed of 1.9-2.4 cm s-1. Cyprids swam against the near-bed flow (negative rheotaxis) and the swimming speed (1.8 cm s-1) was close to the critical speed that permitted temporary attachment. We conclude that temporary attachment in barnacle cyprids requires upstream swimming to maintain a fixed position relative to the substrate for at least 0.1 s. This behaviour may explain the ability of barnacles to recruit to high-flow environments and give cyprids flexibility in the pre-settlement choice of substrates based on flow regime. PMID:27463968

  16. Effects of temperature and salinity on larval development of Elminius modestus (Crustacea, Cirripedia) from Helgoland (North Sea) and New Zealand

    NASA Astrophysics Data System (ADS)

    Harms, J.

    1986-12-01

    Larvae of Elminius modestus (Darwin) from four different populations (Portobello, Leigh, Doubtless Bay [New Zealand] and Helgoland [North Sea]) were reared at different salinity and temperature combinations. The larvae of E. modestus from Helgoland developed successfully at a wide range of temperature (6° to 24 °C) and salinity (20 to 50 ‰ S). Mortality was highest at 10 ‰ S; only at 12° and 18 °C did a small percentage develop to the cypris. The larvae from New Zealand were reared at a temperature range of 12° 24 °C at 20, 30 and 40 ‰ S; mortality increased in all populations at all salinities with decreasing temperature and was extremely high at 12 °C and 40 ‰ S. The temperature influence on larval duration could be described in all cases by a power function. No significant differences in temperature influences on developmental times between the tested salinities were found, except for the Portobello population at 20 ‰ S. Significant differences were found in the temperature influence on larval development between the populations from Helgoland and the North Island of New Zealand (Leigh, Doubtless Bay). No differences were found between the Helgoland and Portobello population. The pooled data for the temperature influence on the larval development of the three tested New Zealand populations at 20, 30 and 40 ‰ S and the pooled Helgoland data at 20, 30 and 40 ‰ S show highly significant differences. Larval size (stage VI) was influenced by experimental conditions. The larvae grew bigger at low temperatures and attained their maximum size at 30 ‰ S (Helgoland). There was a strong reduction in larval size at temperatures from 18° to 24 °C. The larvae of the New Zealand populations were smaller than those from Helgoland. The greatest difference in size existed between the larvae from Portobello and Helgoland.

  17. Bioassays and selected chemical analysis of biocide-free antifouling coatings.

    PubMed

    Watermann, B T; Daehne, B; Sievers, S; Dannenberg, R; Overbeke, J C; Klijnstra, J W; Heemken, O

    2005-09-01

    Over the years several types of biocide-free antifouling paints have entered the market. The prohibition of biocidal antifouling paints in special areas of some European countries such as Sweden, Denmark and Germany has favoured the introduction of these paints to the market. Several types of biocide-free antifouling paints were subjected to bioassays and selected chemical analysis of leachate and incorporated substances. Both non-eroding coatings (silicones, fibre coats, epoxies, polyurethane, polyvinyl) and eroding coatings (SPCs, ablative) were tested to exclude the presence of active biocides and dangerous compounds. The paints were subjected to the luminescent bacteria test and the cypris larvae settlement assay, the latter delivering information on toxicity as well as on efficacy. The following chemical analyses of selected compounds of dry-film were performed: The results of the bioassays indicated that none of the coatings analysed contained leachable biocides. Nevertheless, some products contained or leached dangerous compounds. The analyses revealed leaching of nonylphenol (up to 74.7 ng/cm2/d after 48 h) and bisphenol A (up to 2.77 ng/cm2/d after 24 h) from epoxy resins used as substitutes for antifouling paints. The heavy metal, zinc, was measured in dry paint film in quantities up to 576,000 ppm in erodable coatings, not incorporated as a biocide but to control the rate of erosion. Values for TBT in silicone elutriates were mostly below the detection limit of 0.005 mg/kg. Values for DBT ranged between <0.005 and 6.28 mg/kg, deriving from catalysts used as curing agents. Some biocide-free paints contained leachable, toxic and dangerous compounds in the dry film, some of which may act as substitutes for biocides or are incorporated as plasticizers or catalysts. Implications to environmental requirements and legislation are discussed. PMID:15878605

  18. Analysis of the Behaviours Mediating Barnacle Cyprid Reversible Adhesion

    PubMed Central

    Aldred, Nick; Høeg, Jens T.; Maruzzo, Diego; Clare, Anthony S.

    2013-01-01

    When exploring immersed surfaces the cypris larvae of barnacles employ a tenacious and rapidly reversible adhesion mechanism to facilitate their characteristic ‘walking’ behaviour. Although of direct relevance to the fields of marine biofouling and bio-inspired adhesive development, the mechanism of temporary adhesion in cyprids remains poorly understood. Cyprids secrete deposits of a proteinaceous substance during surface attachment and these are often visible as ‘footprints’ on previously explored surfaces. The attachment structures, the antennular discs, of cyprids also present a complex morphology reminiscent of both the hairy appendages used by some terrestrial invertebrates for temporary adhesion and a classic ‘suction cup’. Despite the numerous analytical approaches so-far employed, it has not been possible to resolve conclusively the respective contributions of viscoelastic adhesion via the proteinaceous ‘temporary adhesive’, ‘dry’ adhesion via the cuticular villi present on the disc and the behavioural contribution by the organism. In this study, high-speed photography was used for the first time to capture the behaviour of cyprids at the instant of temporary attachment and detachment. Attachment is facilitated by a constantly sticky disc surface – presumably due to the presence of the proteinaceous temporary adhesive. The tenacity of the resulting bond, however, is mediated behaviourally. For weak attachment the disc is constantly moved on the surface, whereas for a strong attachment the disc is spread out on the surface. Voluntary detachment is by force, requiring twisting or peeling of the bond – seemingly without any more subtle detachment behaviours. Micro-bubbles were observed at the adhesive interface as the cyprid detached, possibly an adaptation for energy dissipation. These observations will allow future work to focus more specifically on the cyprid temporary adhesive proteins, which appear to be fundamental to adhesion

  19. Degradation kinetics of a potent antifouling agent, butenolide, under various environmental conditions.

    PubMed

    Chen, Lianguo; Xu, Ying; Wang, Wenxiong; Qian, Pei-Yuan

    2015-01-01

    Here, we investigated the degradation kinetics of butenolide, a promising antifouling compound, under various environmental conditions. The active ingredient of the commercial antifoulant SeaNine 211, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), was used as positive control. The results showed that the degradation rate increased with increasing temperature. Half-lives of butenolide at 4 °C, 25 °C and 40 °C were>64 d, 30.5 d and 3.9 d, respectively. Similar half-lives were recorded for DCOIT: >64 d at 4 °C, 27.9 d at 25 °C and 4.5d at 40 °C. Exposure to sunlight accelerated the degradation of both butenolide and DCOIT. The photolysis half-lives of butenolide and DCOIT were 5.7 d and 6.8 d, respectively, compared with 9.7 d and 14.4 d for the dark control. Biodegradation led to the fastest rate of butenolide removal from natural seawater, with a half-life of 0.5 d, while no obvious degradation was observed for DCOIT after incubation for 4 d. The biodegradative ability of natural seawater for butenolide was attributed mainly to marine bacteria. During the degradation of butenolide and DCOIT, a gradual decrease in antifouling activity was observed, as indicated by the increased settlement percentage of cypris larvae from barnacle Balanus amphitrite. Besides, increased cell growth of marine diatom Skeletonema costatum demonstrated that the toxicity of seawater decreased gradually without generation of more toxic by-products. Overall, rapid degradation of butenolide in natural seawater supported its claim as a promising candidate for commercial antifouling industry. PMID:25460745

  20. Analysis of the behaviours mediating barnacle cyprid reversible adhesion.

    PubMed

    Aldred, Nick; Høeg, Jens T; Maruzzo, Diego; Clare, Anthony S

    2013-01-01

    When exploring immersed surfaces the cypris larvae of barnacles employ a tenacious and rapidly reversible adhesion mechanism to facilitate their characteristic 'walking' behaviour. Although of direct relevance to the fields of marine biofouling and bio-inspired adhesive development, the mechanism of temporary adhesion in cyprids remains poorly understood. Cyprids secrete deposits of a proteinaceous substance during surface attachment and these are often visible as 'footprints' on previously explored surfaces. The attachment structures, the antennular discs, of cyprids also present a complex morphology reminiscent of both the hairy appendages used by some terrestrial invertebrates for temporary adhesion and a classic 'suction cup'. Despite the numerous analytical approaches so-far employed, it has not been possible to resolve conclusively the respective contributions of viscoelastic adhesion via the proteinaceous 'temporary adhesive', 'dry' adhesion via the cuticular villi present on the disc and the behavioural contribution by the organism. In this study, high-speed photography was used for the first time to capture the behaviour of cyprids at the instant of temporary attachment and detachment. Attachment is facilitated by a constantly sticky disc surface - presumably due to the presence of the proteinaceous temporary adhesive. The tenacity of the resulting bond, however, is mediated behaviourally. For weak attachment the disc is constantly moved on the surface, whereas for a strong attachment the disc is spread out on the surface. Voluntary detachment is by force, requiring twisting or peeling of the bond - seemingly without any more subtle detachment behaviours. Micro-bubbles were observed at the adhesive interface as the cyprid detached, possibly an adaptation for energy dissipation. These observations will allow future work to focus more specifically on the cyprid temporary adhesive proteins, which appear to be fundamental to adhesion, inherently sticky and

  1. Ostracoda (Crustacea) association and a new species (Dolerocypris anatolia nov. sp.) from the Pliocene-Pleistocene Afşin-Elbistan (Kahraman Maraş) Coal Basin of Turkey

    NASA Astrophysics Data System (ADS)

    Tunoǧlu, Cemal; Besbelli, Berk; Ertekin, İbrahim Kadri

    2012-04-01

    The Afşin-Elbistan Coal Basin, which is one of the largest and most important Pliocene-Pleistocene lignite basins of Turkey, is located in Eastern Anatolia. The basin was formed between two normal faults having NE-SW direction and these faults controlled both the sedimentation and the subsidence. The coal horizon of over 50 meters in thickness indicates the balance between the sedimentation and subsidence rates, and was preserved during peat deposition. Coals were generated in this extensive and shallow freshwater lake and evolved from the Pliocene to Pleistocene. Typical faunal and floral assemblages of this ancient Afşin-Elbistan freshwater lake are Ostracoda, Mollusca (Gastropoda and Pelecypoda), spore-pollen and Characeae (gyrogonites). Eleven Cypridoidea species were identified from the investigation area. Eight of them are already known (Candona neglecta Sars, Candona iliensis Mandelstam, Candona aff. candida (Müller), Pseudocandona compressa (Koch), Cyclocypris ovum (Jurine), Ilyocypris gibba (Ramdohr), Cypris pubera Müller, Heterocypris salina (Brady)), whereas three belong to open nomenclature — Candona sp. and Eucypris sp.; Dolerocypris anatolia nov. sp. is proposed as a new species. Dolerocypris Kaufmann is one of the largest genera among the freshwater Ostracoda. It has a very wide geographical distribution. Representatives of this genus are actively swimming species found in shallow zones of freshwater lakes and reported from small grassy water bodies with megascopic plants. Dolerocypris anatolia nov. sp. is recorded from core samples of the Pliocene-Pleistocene Afşin-Elbistan Coal Basin for the first time.

  2. Holocene evolution of Lake Shkodra: Multidisciplinary evidence for diachronic landscape change in northern Albania

    NASA Astrophysics Data System (ADS)

    Mazzini, Ilaria; Gliozzi, Elsa; Galaty, Michael; Bejko, Lorenc; Sadori, Laura; Soulié-Märsche, Ingeborg; Koçi, Rexhep; Van Welden, Aurelien; Bushati, Salvatore

    2016-03-01

    A multidisciplinary micro-paleontological study of a sediment core (SK19) drilled in the coastal area of Lake Shkodra, northern Albania, integrated with archaeological data from the Projekti Arkeologjikë i Shkodrës (PASH), provides compelling evidence for a long-term relationship between Shkodra's natural environment and its inhabitants. Charophyte and ostracod data recovered from SK19 combined with those already studied from the distal core SK13 (Mazzini et al., 2015), reveal important information concerning the changing characteristics of the water body through time. In particular, the ostracod fauna display a truly Balkanic character with eight taxa endemic to the area. Palaeoenvironmental analysis of the two cores indicates that a wide marshland extended towards the present eastern coast of the lake, fed discontinuously both by surface- and ground-water, beginning sometime before 12,140 cal yrs BP. For about 7000 years ostracods do not record any significant changes, whereas the Characeae record in the proximal zone displays important variations. Those variations do not match any of the climatic oscillations revealed in previous studies by δ18O or pollen data, thereby implicating human activities. Ostracods and charophytes indicate that permanent shallow waters occurred in the Shkodra basin only around 5800 cal yrs BP. Historical sources of the Roman Empire indicate a swamp (the Palus labeatis), crossed by the River Morača, which flowed into the River Buna. Evidence for local fires, whether natural or anthropogenic, is recorded in SK13, scattered between 4400 and 1200 yrs BP. From 4400 to 2000 yrs BP, during the Bronze and Iron Age, hill forts ringed the marsh and burial mounds marked its edges. But around 2000 cal yrs BP, a dramatic change in the water body occurred: the disappearance of Characeae. Possibly fires were used for the elimination of natural vegetation and the subsequent cultivation of olive and walnut trees, causing an increase on organic

  3. Evaluation of foraminiferal trace element cleaning methods on the Mg/Ca of marine ostracoda Krithe

    NASA Astrophysics Data System (ADS)

    Gray, W. R.; Holmes, J. A.; Shevenell, A.

    2012-12-01

    Mg/Ca of marine ostracod Krithe calcite is a potentially important tool for reconstructing oceanic bottom water (150-4000m) temperatures, as core top studies show ostracod Mg uptake is unaffected by carbonate ion saturation. Rigorous cleaning procedures, routinely used to remove clays, organic matter and Fe-Mn-oxides in trace element studies of foraminifera are not regularly applied to marine ostracods. Here we assess the possibility of reducing the analytical uncertainty in Krithe Mg/Ca analyses by employing foraminiferal trace element cleaning procedures and determining the effects of these cleaning procedures on valve chemistry. Using coretop samples of adult and juvenile male Krithe pernoides valves from boxcore OCE205-50BC (26.23oN, 77.7oW, 817m water depth), we apply methanol sonication, hydrogen peroxide oxidation, and hydrazine reduction to single ostracod valves, and sequentially assess the impact of each cleaning step. We compare the results from each cleaning step to valves cleaned using the traditional ethanol/DI rinse method. Significant correlation between Al/Fe and Mn/Fe respectively indicate that clays and Fe-Mn-oxides are detectable in traditionally cleaned samples. Mn and Al covary with Mg in juvenile but not in adult valves, indicating that clays and Fe-Mn-oxides exert a significant control on the Mg/Ca of low valve weight juveniles. Results of our Krithe cleaning experiments confirm that the removal of clays by sonication in methanol results in a decrease in average Fe, Al and Mn values, as well as a reduction in Mg/Ca by 1 mmol/mol in juveniles and 0.5 mmol/mol in adults. Following hydrogen peroxide oxidation samples show a reduction in Fe, Al and Mn concentrations with no significant change in valve Mg/Ca (±0.15 mmol/mol). After reductive cleaning we observe a significant decrease in valve Mg (>1 mmol/mol in juveniles), however there is little effect on Mn and Fe. Examination of adult and juvenile Krithe valves using scanning electron

  4. Benthic foraminifera as bioindicator for cold-water coral reef ecosystems along the Irish margin

    NASA Astrophysics Data System (ADS)

    Margreth, Stephan; Rüggeberg, Andres; Spezzaferri, Silvia

    2009-12-01

    Cold-water coral ecosystems building cold-water carbonate mounds occur worldwide and are especially developed along the European margin, from northern Norway to the Gulf of Cadiz. A remarkable mound province is documented southwest of Ireland along the Porcupine and Rockall Banks. In this area carbonate mounds are formed in water depths between 500 and 1200 m and are often densely settled by cold-water coral ecosystems offering many ecological niches for benthic foraminifera. We investigated total (unstained) benthic foraminiferal assemblages from surface sediments (0-1 cm, >63 μm size fraction) of this region with the aim to trace their distribution patterns and to test if they can be used as bioindicators for facies characterization in different parts of carbonate mound systems. Our quantitative data were further statistically treated with non-metric multidimensional scaling (nMDS) based on Bray-Curtis similarity matrix to highlight community patterns that were not readily apparent. Our results indicate that different benthic foraminiferal assemblages characterize different facies along cold-water carbonate mounds and are related to the environmental conditions and available substrates. The following facies can be described: (1) the Off-Mound Facies is dominated by uvigerinids and other infaunal species; (2) the Dropstone Facies is characterized by infaunal Globocassidulina subglobosa and attached-epifaunal Cibicidoides sp.; (3) the Dead Coral Facies is characterised by epifaunal species (e.g., Planulina ariminensis, Hanzawaia boueana) and infaunal species ( Spiroplectinella wrightii, Angulogerina angulosa, Epistominella vitrea); (4) the Living Coral Facies includes both infaunal and epifaunal species, but is dominated by the epifaunal Discanomalina coronata; and (5) the Sandwave Facies contains high abundances of epifaunal species including D. coronata. Based on this distribution, we propose D. coronata, as an indicator species to identify active mounds and

  5. Distribution of Holocene deep-sea benthonic foraminifera in the southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Corliss, Bruce H.

    1983-02-01

    The distribution of deep-sea benthonic foraminifera in core top samples from the southwest Indian Ocean is examined. Principal component analysis reveals two major assemblages. One assemblages between 3600 and 4800-m water depth is dominated by Episominella umbonifera and is associated with cold ( θ = -0.3 to 0.8°C), low salinity (34.66 to 34.72 × 10 -3) Antarctic Bottom Water in the Crozet Basin, in fracture zones, and on the flanks of the Southwest Indian Ridge. A second assemblage, dominated by Planulina wuellerstorfi, Globocassidulina subglobasa, Astrononion echolsi and Pullenia bulloides, is between 1600 and 3800 m on the Crozet Plateau, Madagascar Ridge, Central Indian Ridge, and Southwest Indian Ridge and is associated with relatively warm ( θ = 0.8 to 2.6°C), high salinity (34.72 to 34.76 × 10 -3) North Atlantic Deep Water. The third principal component divides the P. wuellerstorfi assemblage into two subgroups. One is dominated by Epistominella exigua, P. bulloides, P. wuellerstorfi, and A. echolsi and a second is dominated by G. subglobosa. The distribution of the E. umbonifera assemblage and previous hydrographic studies suggest that AABW flows as a western boundary contour current in the Crozet Basin and penetrates fracture zones in the Southwest Indian Ridge between 55 and 57°E and near 66°E as it travels northward into the Madagascar and Mascarene basins. The faunal-water mass associations from the southeast Indian Ocean are compared; the most notable faunal difference is the absence of Uvigerina as a dominant taxon in the southwest Indian Ocean. A comparison of dissolved oxygen and Uvigerina data shows that oxygen is not a major influence upon the distribution of Uvigerina. A correlation analysis of the faunal data and water depth, potential temperature, in situ temperature, salinity, dissolved oxygen, and 1 - Ω, an index of calcium carbonate undersaturation, was carried out to determine the relationships between fauna and hydrography. The

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

    NASA Astrophysics Data System (ADS)

    Caulle, C.; Koho, K. A.; Mojtahid, M.; Reichart, G. J.; Jorissen, F. J.

    2014-02-01

    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: 2-78 μM) and bathymetric (885-3010 m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63-125 μm, 125-150 μm and >150 μm). The larger foraminifera (>125 μm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63-125 μm 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: 2 μM), 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: 5-16 μM), is composed of species that 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: 26-78 μM), 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

  7. Live foraminiferal faunas (Rose Bengal stained) from the northern Arabian Sea: links with bottom-water oxygenation

    NASA Astrophysics Data System (ADS)

    Caulle, C.; Koho, K. A.; Mojtahid, M.; Reichart, G. J.; Jorissen, F. J.

    2013-09-01

    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: 2-78 μM) and bathymetric (885-3010 m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63-125 μm, 125-150 μm and > 150 μm). The larger foraminifera (> 125 μm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63-125 μm fraction, calcareous taxa were more abundant, especially in the core of the OMZ, suggesting an opportunistic behaviour. On the basis of a Principal Component Analysis, three foraminiferal groups were identified, reflecting the environmental parameters along the study transect. The faunas from the shallowest stations, in the core of the OMZ (BWO: 2 μM), were composed of "low oxygen" species, typical of the Arabian Sea OMZ (e.g., Rotaliatinopsis semiinvoluta, Praeglobobulimina spp. , Bulimina exilis, Uvigerina peregrina typeparva). 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: 5-16 μM), is composed of more cosmopolitan taxa tolerant to low-oxygen concentrations (Globocassidulina subglobosa, Ehrenbergina trigona). Below the OMZ (BWO: 26-78 μM), where food availability is more limited and becomes increasingly restricted to surficial sediments, more cosmopolitan calcareous taxa were present, such as Bulimina aculeata, Melonis barleeanus, Uvigerina peregrina and Epistominella exigua. Miliolids were uniquely observed in this last group, reflecting the higher BWO. At these deeper sites, the faunas exhibit a clear depth

  8. PubMed

    Gross, Martin; Piller, Werner E; Scholger, Robert; Gitter, Frank

    2011-12-01

    A multidisciplinary study was performed on a c. 30 m thick, limnic-deltaic sequence in the Styrian Basin (Austria). Geophysical (gamma ray activity, rock magnetism), geochemical (organic carbon, sulphur) and sedimentological observations were combined with palaeontological information (mainly ostracods). On this base, several ecological factors were deduced (terrigenous influx, salinity, water depth and oxygenation). Based on integrated stratigraphy as well as on palaeomagnetic results the whole section is set to Chron C5r.2r-1n (11.308-11.263 Ma) and covers a period of less than 45 kyr. In addition to the long-term record, we analysed short-term changes by high-resolution sampling (5 mm sample interval; ostracods, magnetic susceptibility). This ~ 2.3 m-thick interval spans in total < 3500 yr with an individual sample resolution of a few years only. The combination of these data permit the description of the palaeoenvironmental evolution of the section in detail: at the base of the section, the development of a conifer swamp on the lakeside of Lake Pannon is documented. This almost freshwater swamp existed for some centuries before it became extinct within a few decades due to a rise of the water-table. The drowning is related to a transgression of Lake Pannon, which triggered the establishment of a brackish-water fauna as well as greigite formation in the lake sediments. In general, the ongoing transgression favoured benthic life due to increased salinity (up to mesohaline conditions). The high-resolution ostracod and magnetic susceptibility record reflect short-term fluctuations in bottom-water ventilation. These oscillations probably range in the order of centuries and decades and are possibly related to climatic shifts. Later, the successive deepening of the lake resulted in a significant faunal turnover. A meromictic system with a well-established, oxygen-depleted hypolimnion developed. Finally, the limnic phase was replaced by a prograding deltaic

  9. Late Pleistocene-Holocene Climate Change Inferred from Fossil Fauna in the Marmara Sea, Turkey

    NASA Astrophysics Data System (ADS)

    Gurung, D.; McHugh, C. M.; Ryan, W. B.; Giosan, L.; Mart, Y.; Cagatau, N.

    2006-12-01

    Paleoenvironmental changes that document the reconnection of the Marmara Sea to the world's oceans were investigated from sediment cores and high-resolution CHIRP subbottom profiles acquired by the R/V Mediterranean Explorer in 2005. The transition from a glacial fresh/brackish water lake to a sea took place after global sea-level reached the Dardanelles outlet sill depth of -85m. We surveyed the continental shelf-slope boundary along the northern margin at Cekmece and the eastern margin at the Prince Islands in water depths extending from 80 to 135 m. Mollusk, ostracod, and foraminiferal faunal assemblages calibrated to radiocarbon chronology and sediment analyses reveal the mixing of marine and lake sediments, and very high sedimentation rates, 50 cm per 1000 years, from ~12 to 10.5 cal ka BP. Very high sedimentation rates (70 cm/1000 years) and an abrupt transition from lake stage to marine were documented along the southern shelf at Imrali from ~12.5 to 11.5 cal ka BP. This older age was derived from foraminifers. Marine mollusks Corbula sp., Lucinella sp., and Gouldia sp. are found in sand beds contained within stiff clays. The sands are rich in spherical, calcium carbonate, oolites commonly associated with shallow environments, agitated waters, and warm evaporative climates. The stiff clays contain low salinity 1-5 per mil bivalve Dreissena rostriformis, gastropod, Theodoxus fluviatilis, and fresh brackish ostracods and are interpreted as lake sediments. Paleoshorelines along the northern, eastern, and southern shelves were below the Dardanelles outlet sill of -85m at the time of marine reconnection. The drawdown of Marmara Lake prior to marine intrusion is also consistent with regional aridity. After 10.5 cal ka BP sediments and faunal assemblages are fully marine with mollusks (Corbula sp., Lucinella sp., Turritela sp., and Gouldia sp) and ostracods. Even though benthic foraminifers are rich after the marine conditions were established, planktonic

  10. Calcareous assemblages of the southeastern Mediterranean low-tide estuaries - Seasonal dynamics and paleo-environmental implications

    NASA Astrophysics Data System (ADS)

    Avnaim-Katav, Simona; Agnon, Amotz; Sivan, Dorit; Almogi-Labin, Ahuva

    2016-02-01

    The study of estuarine ecosystems is essential for protecting and reestablishing their threatened biota. In this research the spatio-temporal variations in the distribution patterns of foraminifera, ostracods and molluscs are analyzed in surficial sediments sampled in 2012/13 at six low-tide estuaries of the southeastern Mediterranean coast. Live assemblages are studied using multivariate statistical analyses to determine their ecological preferences and seasonal dynamics whereas the dead assemblages are used to establish a reference baseline for future paleoenvironmental reconstruction. The statistical analysis indicates that salinity, TOC and % carbonate are the main environmental factors explaining 60% of the cumulative variance and controlling the distribution pattern of the different brackish taxa encountered in these estuaries. The foraminifera Ammonia tepida and some miliolids (Quinqueloculina and Varidentella) inhabit most estuaries during summer when salinities of 13-18 psu and temperatures of 26-34 °C occur. At the Naaman stream the agglutinated species Birsteiniolla macrostoma and Trichohyalus aguayoi dominate the assemblage during autumn and winter, respectively when salinities of 3-7 psu and temperature of 18-24 °C prevail. High abundance of the monospecific assemblage of the ostracod Cyprideis torosa was encountered at the Tanninim year round in oligohaline water. The gastropod Heleobia phaeniciaca prefers living at the Naaman and Tanninim streams while Pyrgophorus sp., an invasive and low salinity species, continue colonizing more stream reaches along the Israeli coast. The dead assemblages are composed of high numbers of local and transported species. It includes post storm-surge sediments containing high numbers of inland fresh and brackish water species transported by the floods. Those are mixed with inner to mid-shelf benthic and planktonic foraminifera, ostracods and molluscs. Transportation of the marine organisms a few hundred of meters

  11. Late Glacial temperature and precipitation changes in the lowland Neotropics by tandem measurement of δ 18O in biogenic carbonate and gypsum hydration water

    NASA Astrophysics Data System (ADS)

    Hodell, David A.; Turchyn, Alexandra V.; Wiseman, Camilla J.; Escobar, Jaime; Curtis, Jason H.; Brenner, Mark; Gilli, Adrian; Mueller, Andreas D.; Anselmetti, Flavio; Ariztegui, Daniel; Brown, Erik T.

    2012-01-01

    We applied a new method to reconstruct paleotemperature in the tropics during the last deglaciation by measuring oxygen isotopes of co-occurring gypsum hydration water and biogenic carbonate in sediment cores from two lakes on the Yucatan Peninsula. Oxygen and hydrogen isotope values of interstitial and gypsum hydration water indicate that the crystallization water preserves the isotopic signal of the lake water, and has not undergone post-depositional isotopic exchange with sediment pore water. The estimated lake water δ18O is combined with carbonate δ18O to calculate paleotemperature. Three paired measurements of 1200-yr-old gypsum and gastropod aragonite from Lake Chichancanab, Mexico, yielded a mean temperature of 26 °C (range 23-29.5 °C), which is consistent with the mean and range of mean annual temperatures (MAT) in the region today. Paired measurements of ostracods, gastropods, and gypsum hydration water samples were measured in cores from Lake Petén Itzá, Guatemala, spanning the Late Glacial and early Holocene period (18.5-10.4 ka). The lowest recorded temperatures occurred at the start of Heinrich Stadial (HS) 1 at 18.5 ka. Inferred temperatures from benthic ostracods ranged from 16 to 20 °C during HS 1, which is 6-10 °C cooler than MAT in the region today, whereas temperatures derived from shallow-water gastropods were generally warmer (20-25 °C), reflecting epilimnetic temperatures. The derived temperatures support previous findings of greater tropical cooling on land in Central America during the Late Glacial than indicated by nearby marine records. Temperature increased in two steps during the last deglaciation. The first occurred during the Bolling-Allerod (B-A; from 14.7 to 13 ka) when temperature rose to 20-24 °C towards the end of this period. The second step occurred at 10.4 ka near the beginning of the Holocene when ostracod-inferred temperature rose to 26 °C, reflecting modern hypolimnetic temperature set during winter, whereas

  12. Variability in intermediate water circulation of the western Tyrrhenian margin (NE Corsica) over the past 56 kyr

    NASA Astrophysics Data System (ADS)

    Angela, Bassetti Maria; Morelle, Angue Minto'o. Charlie; Emmanuelle, Ducassou; Samuel, Toucanne; Caterina, Morigi; Gwenael, Jouet; Thierry, Mulder

    2015-04-01

    The Marion Dufrene core MD01-2472 made of hemipelagic fine-grained sediments (silt and clays) was collected at 501 m depth on the East Corsica continental slope in 2001 and studied in detail in its 12 uppermost meters. The correlation between sedimentological parameters (Sortable Silt), isotopic data and 14C dating allowed to establish the chronology of main climate events (Younger Dryas/YD, Bölling-Alleröd/B-A, Heinrich events/HS) on this record and to evaluate the impact of major climate oscillations on bottom water condition variability. The sea temperature changes are identified thanks to the planktonic foraminifera assemblages. HS are marked by planktonic foraminifers with peaks of the polar species N. pachyderma (left-coiling), whilst interstadials are marked by warm planktonics that become very abundant during the B-A and Holocene. The occurrence of reworked ostracod species (originating from the continental shelf) and the presence of shallow water Elphidium/Ammonia benthic foraminifera are used to estimate the degree of along-slope transport at the core site. This has revealed two intervals of along-slope transport also associated with coarse-grained contourites, deposited during the YD and HS2 episodes. Intervals with Krithe spp. (ostracod), C. wuellerstorfi (benthic foraminifera) indicate bottom water oxygenation during stadials, whereas interstadials are typified by A. acuminata and Paracypris sp (ostracods) indicating low oxygenated environments. The Last Glacial Maximum is dominated by the planktonic foraminifer T. quinqueloba suggesting high surface primary productivity associated with the establishment of mestrophic bottom conditions. During the Holocene, benthic assemblages indicate oligo-mesotrophic conditions and weak hydrodynamic bottom regime. We hypothesize that there is relationship between the Levantine Intermediate Water (LIW) intensification during cold rapid climate events and benthic fauna assemblages due to changes in: 1) bottom water

  13. Controlling factors on a paleo-lake oxygen isotope record (Yammoûneh, Lebanon) since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Develle, Anne-Lise; Herreros, Julien; Vidal, Laurence; Sursock, Alexandre; Gasse, Françoise

    2010-04-01

    Late Quaternary paleoclimatic changes in the Levant are difficult to extract from carbonate oxygen isotope records partly because the factors controlling the terrestrial δ 18O signals are not fully understood in this region characterized by sharp climatic gradients. Here, we address this purpose by presenting the first 14C-dated isotope record from the northern Levant. The record is based on oxygen isotopes from ostracod shells from lacustrine-palustrine deposits accumulated in a small karstic, hydrologically open basin (Yammoûneh), located on the eastern flank of Mount Lebanon. We have first constructed a composite isotopic record obtained from three different ostracod taxa. This yields an oxygen isotope record of ostracods (δ ost) related to the most widespread species ( Ilyocypris inermis), and converted to δ 18O values coeval with calcite precipitated in equilibrium (δ C) with the lake water (δ L). As with other records from the Mediterranean region, the Yammoûneh profile shows maximum and minimum δ C values during the LGM and the early Holocene, respectively, and a slight late Holocene increase. In order to discuss the potential causes of the observed δ 18O values fluctuations (e.g., changes in the isotopic composition of the moisture source, temperature, precipitation minus evaporation (P-E) balance, or atmospheric circulation), we tentatively reconstruct the lake water isotope composition by correcting the δ C values for lake water temperature using regional paleotemperature estimates. Inferred δ L values were then corrected for the isotopic composition of the Eastern Mediterranean sea surface water (the moisture source) derived from planktonic foraminifera δ 18O values corrected for alkenone-based sea surface temperature. Our study suggests that Holocene δ L fluctuations are primarily linked to changes in the sea surface water composition (source effect) amplified by enhanced inland rainfall during the early Holocene. During the LGM, low δ L

  14. Biotic and abiotic response to palaeoenvironmental changes at Lake Pannons' western margin (Central Europe, Late Miocene)

    PubMed Central

    Gross, Martin; Piller, Werner E.; Scholger, Robert; Gitter, Frank

    2011-01-01

    A multidisciplinary study was performed on a c. 30 m thick, limnic–deltaic sequence in the Styrian Basin (Austria). Geophysical (gamma ray activity, rock magnetism), geochemical (organic carbon, sulphur) and sedimentological observations were combined with palaeontological information (mainly ostracods). On this base, several ecological factors were deduced (terrigenous influx, salinity, water depth and oxygenation). Based on integrated stratigraphy as well as on palaeomagnetic results the whole section is set to Chron C5r.2r−1n (11.308–11.263 Ma) and covers a period of less than 45 kyr. In addition to the long-term record, we analysed short-term changes by high-resolution sampling (5 mm sample interval; ostracods, magnetic susceptibility). This ~ 2.3 m-thick interval spans in total < 3500 yr with an individual sample resolution of a few years only. The combination of these data permit the description of the palaeoenvironmental evolution of the section in detail: at the base of the section, the development of a conifer swamp on the lakeside of Lake Pannon is documented. This almost freshwater swamp existed for some centuries before it became extinct within a few decades due to a rise of the water-table. The drowning is related to a transgression of Lake Pannon, which triggered the establishment of a brackish-water fauna as well as greigite formation in the lake sediments. In general, the ongoing transgression favoured benthic life due to increased salinity (up to mesohaline conditions). The high-resolution ostracod and magnetic susceptibility record reflect short-term fluctuations in bottom-water ventilation. These oscillations probably range in the order of centuries and decades and are possibly related to climatic shifts. Later, the successive deepening of the lake resulted in a significant faunal turnover. A meromictic system with a well-established, oxygen-depleted hypolimnion developed. Finally, the limnic phase was replaced by a prograding

  15. High-latitude application of sup 87 Sr/ sup 86 Sr: Correlation of Nuwok beds on North Slope, Alaska, to standard Oligocene chronostratigraphy

    SciTech Connect

    McNiel, D.H. ); Miller, K.G. )

    1990-05-01

    Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) calculated from three samples of benthic forminifers and one mallusc indicate an age range from 23.8 to 27.0 Ma for the Nuwok Member of the Sagavanirktok Formation, eastern North Slope, Alaska. Previous correlations derived paleontologically (foraminifers, ostracodes, and molluscs) for the Nuwok beds have differed greatly (Oligocene to Pliocene), but strontium isotope ratios substantiate the late Oligocene age determined from benthic foraminifers. The results constitute an important test case, illustrating the effectiveness of the strontium isotope method in correlating high-latitude carbonate samples to the standard Oligocene chronostratigraphy. In addition, a sample from the Kugmallit sequence in the Beaufort Sea Edlok N-56 well provided a strontium isotope age estimate of 30.7 Ma. The Edlok sample was paleontologically correlated to just below the early/late Oligocene boundary (30.0 Ma).

  16. Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay coastal system, California

    NASA Astrophysics Data System (ADS)

    McGann, M.; Erikson, L. H.; Wan, E.; Powell, C., II; Maddocks, R. F.

    2012-12-01

    The biological, anthropogenic, and volcanic constituents of more than 300 samples collected from 1995 to 2010 in San Francisco Bay and the nearby coastal area were analyzed to discern patterns of sediment transport and deposition. The biological constituents investigated include microfauna (benthic and planktic foraminifers, ostracods, radiolarians, diatoms, and thecamoebians), macrofauna (bivalve mollusks, gastropods, barnacles, bryozoa, worm tubes, echinoids, crabs, and fish fragments), and flora (woody stems, roots, spores, and seeds). The distributional pattern of the benthic foraminifers was further refined by Q-mode cluster analysis into four assemblages that reflect where the taxa reside: the Brackish Shallow Subtidal Assemblage, the Estuarine Shallow Subtidal Assemblage, the Estuarine Intermediate/Deep Subtidal Assemblage, and the Nearshore Marine Assemblage. The anthropogenic objects recovered in this study include welding slag and glass microspheres most likely used to increase roadway line reflectivity. The volcanic constituents are glass shards of the Pliocene (3.27 Ma) Nomlaki Tuff, and Miocene tephra mostly derived from the Great Central Valley (including from the 23-19 Ma Valley Springs Formation, among others) and from the Sonoma Volcanic Field of California. The presence of allochthonous sedimentological constituents in this study was used to identify pathways of sediment transport and deposition within the San Francisco Bay coastal system. Several patterns have been identified: 1) volcanic glass shards are transported from the Great Central Valley through the delta to all regions of the bay, including the extreme end of south bay, as well as along the coast outside the bay and southward to Pedro Point; 2) microorganisms (benthic and planktic foraminifers, ostracods, diatoms, and radiolaria) from the marine realm outside San Francisco Bay are found in the estuary at the southern end of south bay, commonly in the middle of San Pablo Bay, and

  17. Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

    NASA Astrophysics Data System (ADS)

    Rofes, Juan; Garcia-Ibaibarriaga, Naroa; Aguirre, Mikel; Martínez-García, Blanca; Ortega, Luis; Zuluaga, María Cruz; Bailon, Salvador; Alonso-Olazabal, Ainhoa; Castaños, Jone; Murelaga, Xabier

    2015-09-01

    Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere.

  18. Benthic myodocopid Ostracoda (Philomedidae) from the Southern Ocean.

    PubMed

    Chavtur, Vladimir G; Keyser, Dietmar

    2016-01-01

    This study is based on the material of myodocopid ostracodes of the family Philomedidae collected by the Russian Antarctic Polar Expeditions (1963-2007) and the Germany Expeditions on R/V "Polarstern" (1990-2002) from the continental shelf and upper slope near the Mawson and Davis stations, the Weddell Seas, the region of the South Shetland Islands near the Russian Polar station "Molodezhnaya" and adjacent waters. Eight philomedid species belonging to two genera were identified in these collections. Scleroconcha tuberculata sp. nov. is described and figured as a new species. Additional descriptions and figures for the species S. gallardoi Kornicker, 1971, Philomedes assimilis Brady, 1907, P. charcoti Daday, 1908, P. heptatrix Kornicker, 1975, P. rotunda Skogsberg, 1920, P. orbicularis Brady, 1907 and P. tetrathrix Kornicker, 1975 are given. Keys for all species of the mentioned genera known from the Southern Ocean are presented. A list of sampling stations and species collected is provided in the Appendix 1. PMID:27470832

  19. Middle Pliocene sea surface temperature variability

    USGS Publications Warehouse

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

    2005-01-01

    Estimates of sea surface temperature (SST) based upon foraminifer, diatom, and ostracod assemblages from ocean cores reveal a warm phase of the Pliocene between about 3.3 and 3.0 Ma. Pollen records and plant megafossils, although not as well dated, show evidence for a warmer climate at about the same time. Increased greenhouse forcing and altered ocean heat transport are the leading candidates for the underlying cause of Pliocene global warmth. Despite being a period of global warmth, this interval encompasses considerable variability. Two new SST reconstructions are presented that are designed to provide a climatological error bar for warm peak phases of the Pliocene and to document the spatial distribution and magnitude of SST variability within the mid-Pliocene warm period. These data suggest long-term stability of low-latitude SST and document greater variability in regions of maximum warming. Copyright 2005 by the American Geophysical Union.

  20. Climate at the edge of human dispersal in the European Middle Pleistocene

    NASA Astrophysics Data System (ADS)

    Horne, David

    2014-05-01

    Pleistocene palaeoclimatic reconstructions based on fossils from sites containing archaeological evidence of human occupation can answer key questions about the climatic context of early human dispersal in Europe. Biological proxies including foraminifera, ostracods, diatoms, chironomid larvae, molluscs and pollen are widely used to estimate palaeoclimatic parameters, typically palaeotemperatures, using indicator species, Mutual Climatic Range (MCR), Modern Analogue Technique (MAT) and transfer function approaches. Any single proxy method will yield plausible results, but there is a need for multi-proxy testing; matching or overlapping results inspire confidence, whereas if independent proxies yield results that do not match or even overlap, one or more must be wrong. The Multi-Proxy Consensus (MPC) approach not only compares two or more proxy results in order to check for agreement, but also offers potential for more refined results to be obtained from the range of mutual agreement between two or more overlapping palaeotemperature ranges. Studies of MIS9 (late Middle Pleistocene) deposits in the Thames-Medway river system in SE England (some of which contain stone implements representing human occupation) have yielded palaeotemperature estimates based on ostracods, beetles, fish, herpetiles, pollen and plant macrofossils. The MPC approach demonstrates the consistency of the results and defines a more continental climate than today (mean July air temperatures similar or 1 degree warmer, mean January air temperatures at least 2 degrees colder). Two River Thames MIS11 sites (Ebbsfleet and Swanscombe) have yielded MPC results indicating summers up to 1.5 degrees warmer and winters at least 5 degrees colder than today. British early Middle Pleistocene sites record the earliest human presence in Europe North of the Alps. At Boxgrove (MIS13), well-known for its rich record of human activity (stone tools and butchered bones), combined ostracod and herpetile MCR results

  1. Suspension freezing of bottom sediment and biota in the Northwest Passage and implications for Arctic Ocean sedimentation

    USGS Publications Warehouse

    Reimnitz, E.; Marincovich, L., Jr.; McCormick, M.; Briggs, W.M.

    1992-01-01

    No evidence was seen for entrainment by bottom adfreezing, bluff slumping, river flooding, dragging ice keels, or significant eolian transport from land to sea. Muddy sediment with pebbles and cobbles, algae with holdfasts, ostracodes with appendages, and well-preserved mollusks and sea urchins were collected from two sites in a 50 km long stretch of turbid ice. These materials indicate that suspension freezing reaching to a water depth of 25-30 m during the previous fall was responsible for entrainment. This mechanism requires rapid ice formation in open, shallow water during a freezing storm, when the ocean becomes supercooled, and frazil and anchor ice attach to and ultimately lift sediment and living organisms to the sea surface. -from Authors

  2. The present environmental scenario of the Nador Lagoon (Morocco).

    PubMed

    Ruiz, F; Abad, M; Olías, M; Galán, E; González, I; Aguilá, E; Hamoumi, N; Pulido, I; Cantano, M

    2006-10-01

    In this paper, we present a multivariate approach (waters, sediments, microfauna) concerning the environmental state of the Nador Lagoon (NE Morocco). The normal water quality parameters (salinity, pH, nutrients) of the dominant marine flows are altered by local fecal water effluents, urban discharges, sewages derived from a water treatment station, and residues originated in a slaughterhouse. The geochemical analyses carried out in surficial sediment samples show very high concentrations of all metals studied near an old iron mine and moderate contents between Nador and its treatment station. Ostracods are good bioindicators of these environmental impacts, with the presence of a highly brackish assemblage in the quieter, more confined areas or the appearance of opportunistic species under hypoxic conditions. In addition, these microcrustaceans are absent in polluted bottom sediments or areas with high hydrodynamic gradients, whereas they decrease in both density and diversity if the subaerial exposure increases. PMID:16624276

  3. Benthic foraminifera of the Panamanian Province: distribution and origins.

    USGS Publications Warehouse

    Crouch, R.W.; Poag, C.W.

    1987-01-01

    Two hundred twenty-nine species of benthic foraminifera have been identified from 96 stations representing 33 localities on the eastern Pacific inner continental shelf, ranging from southern Peru to northern Baja California. Their distributions mark nearshore provincial boundaries that are nearly identical with those previously documented from the distribution of ostracodes and molluscs. Thirteen species are characteristic of the Panamanian Province, one is characteristic of the Chilean-Peruvian Province, and one is characteristic of the newly proposed Sonoran Subprovince. Seventeen species (7%) appear to be endemic to the eastern Pacific. Fifty-eight (25%) of the species recognized are disjunct from population centers in the western Pacific, 134 species (59%) are disjunct from modern assemblages of the Atlanto-Carribean region, and 40 species (17%) are disjunct from both the western Pacific and the Atlanto-Caribbean. The distribution of the remaining 57 species (25%) is poorly documented; we classify them as of unknown origin. -Authors

  4. Description of new members of the family Cylindroleberididae (Ostracoda: Cylindroleberidoidea) from the Southern Ocean.

    PubMed

    Chavtur, Vladimir G; Keyser, Dietmar

    2016-01-01

    We report new ostracod data (Family Cylindroleberididae) based on material collected during the German Expeditions onboard the research vessel "Polarstern" from bathyal and abyssal zones (sampling depth range from 1030 to 3963 m) in the Weddell and Scotia Seas and Drake Passage in 2002 and 2005. Four species belonging to four genera were identified in these collections. A new species, Synasterope pseudomystax, is illustrated and described. A first occurrence of an adult female is registered for Archasterope weddellensis (Kornicker, 1975). Additional description for Parasterope cf. styx Kornicker, 1975 is given. Description of Bathyleberis grossmani Kornicker, 1975 is supplemented with new data on the distribution. Additionally, keys for all species known for Antarctic waters are included. PMID:27470726

  5. New OSL dates of Sangamon Episode biozones from Raymond Basin, Illinois, USA

    NASA Astrophysics Data System (ADS)

    Curry, B.; Wang, H.

    2010-12-01

    Pollen and ostracode records from lake sediments spanning from the penultimate to the last glaciation from south-central Illinois provide key evidence for past climates in central North America. The records come from kettle basins formed in Illinois Episode till. The records are sandwiched at the base and top by “glacial” biozones containing Picea pollen and the cryophyllic ostracode Limnocythere friabilis. Evidence of especially warm and moist conditions during the intervening interglacial conditions includes abundant Liquidambar pollen, and the sub-tropical ostracode Heterocypris punctata. The succession of biozones are repeated in the records of three kettle basins (Raymond, Pittsburg, and Balk Knob). The ostensibly coeval vertebrate record at Hopwood Farm, Illinois, does not have similar pollen or ostracode records, but has fossils of Geochelone crassiscutata, an extinct tortoise related to the modern Galapagos species which presumably could not tolerate the prolonged periods of subfreezing winter temperatures typical of Illinois’ present climate. Although attempts have been made, the chronology of these records has not been adequately resolved. One attempt involved wiggle matching of the 2nd DCA axis of the pollen record (ostensibly a proxy of paleoprecipitation) from Raymond Basin of Zhu and Baker (1995) with the δ13C record from Crevice Cave stalagmites (Dorale et al., 1998, and other data). This correlation suggested that the sediment accumulation rate in the basin was slow (about 1 m/yr), and that a key warm/moist period during the Sangamon Episode coincided with the onset of Marine Isotope Stage 4 (about 75,000 yr). We attempted to verify these age assignments using OSL dating of fine sand from a new sediment core from Raymond Basin, and from adjacent ice-contact deposits. The oldest pollen-bearing lake sediment in Raymond Basin core RB-8 (7 m depth) yielded an OSL date of 129,520 ± 7700 yr. This age coincides with the transition from tundra

  6. Epizooic metazoan meiobenthos associated with tubeworm and mussel aggregations from cold seeps of the northern Gulf of Mexico

    PubMed Central

    Bright, M.; Plum, C.; Riavitz, L.A.; Nikolov, N.; Martinez Arbizu, P.; Cordes, E.E.; Gollner, S.

    2010-01-01

    The abundance and higher taxonomic composition of epizooic metazoan meiobenthic communities associated with mussel and tubeworm aggregations of hydrocarbon seeps at Green Canyon, Atwater Valley, and Alaminos Canyon in depths between 1400 and 2800 m were studied and compared to the infaunal community of non-seep sediments nearby. Epizooic meiofaunal abundances of associated meiobenthos living in tubeworm bushes and mussel beds at seeps were extremely low (usually <100 ind. 10 cm−2), similar to epizooic meiofauna at deep-sea hydrothermal vents, and the communities were composed primarily of nematodes, copepods, ostracods, and halacarids. In contrast, epizooic meiobenthic abundance is lower than previous studies have reported for infauna from seep sediments. Interestingly, non-seep sediments contained higher abundances and higher taxonomic diversity than epizooic seep communities, although in situ primary production is restricted to seeps. PMID:21264038

  7. Fossil invertebrates records in cave sediments and paleoenvironmental assessments: a study of four cave sites from Romanian Carpathians

    NASA Astrophysics Data System (ADS)

    Moldovan, O. T.; Constantin, S.; Panaiotu, C.; Roban, R. D.; Frenzel, P.; Miko, L.

    2015-06-01

    Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new for science, and most of them are indicative for either warm/cold stages or dry/wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures, and hydraulic regimes could be gathered. This paper analyses the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.

  8. Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish.

    PubMed

    Tanaka, Gengo; Parker, Andrew R; Hasegawa, Yoshikazu; Siveter, David J; Yamamoto, Ryoichi; Miyashita, Kiyoshi; Takahashi, Yuichi; Ito, Shosuke; Wakamatsu, Kazumasa; Mukuda, Takao; Matsuura, Marie; Tomikawa, Ko; Furutani, Masumi; Suzuki, Kayo; Maeda, Haruyoshi

    2014-01-01

    Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report on the tissues of its eye, which provides the first record of mineralized rods and cones in a fossil and indicates that this 300 Myr-old fish likely possessed colour vision. PMID:25536302

  9. Synthesis, Spectral Characterization of Several Novel Pyrene-Derived Aminophosphonates and Their Ecotoxicological Evaluation Using Heterocypris incongruens and Vibrio fisheri Tests.

    PubMed

    Lewkowski, Jarosław; Rodriguez Moya, Maria; Chmielak, Marta; Rogacz, Diana; Lewicka, Kamila; Rychter, Piotr

    2016-01-01

    Four diphenyl pyrene-derived aminophosphonates were synthesized. Attempts were made to synthesize diphenyl N-(R)-α-methylbenzylamino(pyren-1-yl)methylphosphonate (3e) in order to obtain the chiral aminophosphonate bearing a pyrene moiety. Because these attempts failed, dimethyl and dibenzyl N-(R)-α-methylbenzyl substituted aminophosphonates 4 and 5 were synthesized and the predominant diastereoisomer of dimethyl aminophosphonate 4 was isolated. The resolution of the diastereomeric mixture of 5 failed. Aminophosphonates 3a-d and the predominant diastereoisomer of 4 were investigated in terms of their ecotoxicity using tests performed on the ostracode Heterocypris incongruens and the fluorescent bacterium Vibrio fisheri. The tests confirmed the moderate-to-high ecotoxicity of aminophosphonates 3a-d and 4, but no evident correlation between the structure and toxicity has been found. PMID:27447596

  10. A mid-european decadal isotope-climate record from 15,500 to 5000 years B.P

    PubMed

    von Grafenstein U; Erlenkeuser; Brauer; Jouzel; Johnsen

    1999-06-01

    Oxygen-isotope ratios of precipitation (delta18OP) inferred from deep-lake ostracods from the Ammersee (southern Germany) provide a climate record with decadal resolution. The record in detail shows many of the rapid climate shifts seen in central Greenland ice cores between 15,000 and 5000 years before the present (B.P.). Negative excursions in the estimated delta18OP from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the North Atlantic. Deviating millennial-scale trends, however, indicate that climate gradients between Europe and Greenland changed systematically, reflecting a gradual rearrangement of North Atlantic circulation during deglaciation. PMID:10356392

  11. Late Devonian sedimentary record of the Paleotethys Ocean - The Mae Sariang section, northwestern Thailand

    NASA Astrophysics Data System (ADS)

    Königshof, P.; Savage, N. M.; Lutat, P.; Sardsud, A.; Dopieralska, J.; Belka, Z.; Racki, G.

    2012-06-01

    An 11 m thick condensed sequence of Late Devonian limestones in northwestern Thailand exhibits faunal associations and sedimentological-/microfacies data which are indicative of a pelagic facies setting. The entire long-ranging section is completely free from clastic input. Similar successions are known worldwide in a few sections only. The Mae Sariang section is characterised by low sedimentation rates as recognised by a number of hardgrounds, neptunian dikes and Fe/Mn crusts. The succession comprises a number of pelagic faunal elements e.g. conodonts, cephalopods and pelagic ostracodes. The fauna records rare macrofossils and the faunal diversity is low. The very condensed section ranges from the Late rhenana to praesulcata conodont biozones, but contains some global events as undoubtedly shown by biostratigraphical and carbon-isotope results (including major Kellwasser and Hangenberg biotic crises). In terms of plate tectonics this important succession most probably belongs to the Inthanon Zone comprising remnants of the Paleotethys Ocean.

  12. New Devonian fossil localities in Bolivia

    NASA Astrophysics Data System (ADS)

    Blieck, A.; Gagnier, P.-Y.; Bigey, F. P.; Edgecombe, G. D.; Janvier, P.; Loboziak, S.; Rachebȩuf, P. R.; Sempere, T.; Steemans, P.

    1996-11-01

    An examination of Palaeozoic sections west of Cochabamba, and west of Lake Poopó, in western Bolivia, was conducted during a field expedition in 1991. The Río Iglesiani valley, west of Cochabamba, surprisingly yielded a Middle Devonian age to all the visited sites, originally supposed to be Ordovician. This result is based on spores, shelly faunas (brachiopods and bivalves), and trilobites. The Copacabana de Andamarca section, west of Lake Poopó, is also dated as Middle Devonian on account of its rather rich fauna (bryozoans, corals, brachiopods, conulariids, hyolithids, tentaculitids, ostracodes, trilobites, crinoids, vertebrates). Both localities correlate to the Icla and/or Huamampampa Formation of the Tarabuco area and Subandean belt, and to the Belén and/or Sica Sica Formation of the northern Altiplano.

  13. Early Tertiary marine fossils from northern Alaska: implications for Arctic Ocean paleogeography and faunal evolution.

    USGS Publications Warehouse

    Marincovich, L., Jr.; Brouwers, E.M.; Carter, L.D.

    1985-01-01

    Marine mollusks and ostracodes indicate a post-Danian Paleocene to early Eocene (Thanetian to Ypresian) age for a fauna from the Prince Creek Formation at Ocean Point, northern Alaska, that also contains genera characteristic of the Cretaceous and Neogene-Quaternary. The life-assocation of heterochronous taxa at Ocean Point resulted from an unusual paleogeographic setting, the nearly complete isolation of the Arctic Ocean from about the end of the Cretaceous until sometime in the Eocene, in which relict Cretaceous taxa survived into Tertiary time while endemic taxa evolved in situ; these later migrated to the northern mid- latitudes. Paleobiogeographic affinities of the Ocean Point assocation with mild temperate faunas of the London Basin (England), Denmark, and northern Germany indicate that a shallow, intermittent Paleocene seaway extended through the Norwegian-Greenland Sea to the North Sea Basin. Early Tertiary Arctic Ocean paleogeography deduced from faunal evidence agrees with that inferred from plate-tectonic reconstructions.-Authors

  14. New data on Berriasian biostratigraphy, magnetostratigraphy, and sedimentology in the Belogorsk area (Central Crimea)

    NASA Astrophysics Data System (ADS)

    Arkadiev, V. V.; Baraboshkin, E. Yu.; Bagaeva, M. I.; Bogdanova, T. N.; Guzhikov, A. Yu.; Manikin, A. G.; Piskunov, V. K.; Platonov, E. S.; Savel'eva, Yu. N.; Feodorova, A. A.; Shurekova, O. V.

    2015-03-01

    The most complete composite Berriasian bio- and magnetostratigraphic section of central Crimea is characterized for the first time with a description of the contact between the carbonate Bedenekyr and terrigenous Bechku formations. The section contains all the standard ammonite zones: jacobi, occitanica, and boissieri. The Malbosiceras chaperi Beds are attributed to the occitanica Zone. The Berriasian section is characterized by six foraminiferal assemblages, ostracods (Costacythere khiamii-Hechticythere belbekensis and Costaythere drushchitzi-Reticythere marfenini beds), and dinocysts (Phobercysta neocomica Beds). The magnetostratigraphic section contains analogs of Chrons M17 and M16 reliably correlated with ammonite zones. On the basis of paleomagnetic data, the Berriasian section of central Crimea is correlated with coeval sections of the Mediterranean Region. The sedimenological analysis confirms accumulation of Berriasian sediments mostly in shallow shelf environments of the carbonate platform.

  15. Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

    PubMed Central

    Rofes, Juan; Garcia-Ibaibarriaga, Naroa; Aguirre, Mikel; Martínez-García, Blanca; Ortega, Luis; Zuluaga, María Cruz; Bailon, Salvador; Alonso-Olazabal, Ainhoa; Castaños, Jone; Murelaga, Xabier

    2015-01-01

    Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere. PMID:26391668

  16. The origin and distribution of subbottom sediments in southern Lake Champlain.

    USGS Publications Warehouse

    Freeman-Lynde, R. P.; Hutchinson, D.R.; Folger, D.W.; Wiley, B.H.; Hewett, M.J.

    1980-01-01

    3 units, correlatable with recent Lake Champlain, late-glacial marine Champlain Sea, and proglacial Lake Vermont sediments, have been identified from seismic reflection profiles and 8 piston cores. Lake Vermont deposits are nonfossiliferous and range from thin to absent nearshore and on bedrock highs to more than 126 m thick near Split Rock Point. Champlain Sea sediments contain marine foraminifers and ostracodes and are fairly uniform in thickness (20-30 m). Recent Lake Champlain sediments range in thickness from 0 to 25 m. Average sedimentation rates for Lake Vermont are considerably higher (4-8 cm/yr) than those for the Champlain Sea (0.8-1.2 cm/yr) and Lake Champlain (0.14-0.15 cm/yr). Bedrock, till, and deltaic and alluvial deposits were also identified.- from Authors

  17. Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments.

    PubMed

    Rofes, Juan; Garcia-Ibaibarriaga, Naroa; Aguirre, Mikel; Martínez-García, Blanca; Ortega, Luis; Zuluaga, María Cruz; Bailon, Salvador; Alonso-Olazabal, Ainhoa; Castaños, Jone; Murelaga, Xabier

    2015-01-01

    Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ(13)C and δ(15)N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ(18)O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña's sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere. PMID:26391668

  18. Fossils from the Middle Jurassic Wanakah formation near Delta in western Colorado

    USGS Publications Warehouse

    O'Sullivan, R. B.; Carey, M.A.; Good, S.C.

    2006-01-01

    The Middle Jurassic Wanakah Formation averages about 30 m in thickness in Colorado. Fossils are sparse and include fish, ostracodes, and trace fossils. A thin (0.03-0.45 m) fossil bed near the middle of the formation extends for some 48 km along the northeast flank of the Uncompahgre Plateau near Delta. The fossil bed at one locality contains one pelecypod identified possibly as Modiolus cf. M. subimbricatus (Meek), as well as other specimens too poorly preserved for identification. Previously, Mytilus was found in the same fossil bed at another locality by C.N. Holmes. The Wanakah Formation is primarily of terrestrial origin, but the fossil bed represents a shallow-marine incursion.

  19. Younger Dryas interval and outflow from the Laurentide ice sheet

    USGS Publications Warehouse

    Moore, T.C., Jr.; Walker, J.C.G.; Rea, David K.; Lewis, C.F.M.; Shane, L.C.K.; Smith, A.J.

    2000-01-01

    A boxmodel of the Great Lakes is used to estimate meltwater flow into the North Atlantic between 8000 and 14,000 calendar years B.P. Controls on the model include the oxygen isotopic composition of meltwaters and lake waters as measured in the shells of ostracodes. Outflow rates are highest when oxygen isotopic values of the lake waters are most negative, denoting a maximum glacial meltwater component. Flow rates reach maximum values before the onset of the Younger Dryas and after it ends. These maxima appear to be correlative with the major meltwater pulses MWP 1A and 1B. Although the resumption of North Atlantic Deep Water formation may be tied to the reduction in ice sheet melting, neither the onset nor the end of the Younger Dryas, as recorded in the Greenland Ice Sheet Project (GISP2) records, appear tied to maxima in meltwater outflow from the Laurentide ice sheet. Copyright 2000 by the American Geophysical Union.

  20. A new species of Elpidium (Crustacea, Ostracoda) from bromeliads in Cusuco National Park, Honduras

    PubMed Central

    Pinto, Ricardo L.; Jocqué, Merlijn

    2013-01-01

    Abstract Passively dispersing aquatic invertebrates such as Ostracoda in restricted aquatic habitats such as bromeliads remain an intriguing observation considering the highly specialised dispersal vectors needed for efficient colonisation. Here we describe a new species of Elpidium, Elpidium merendonense sp. n., collected from bromeliads in the cloud forest from Cusuco National Park, Honduras. Elpidium merendonense sp. n. is a small to medium-sized species that can be easily distinguished from its congeners by its unique outgrowth at the posterior end of the left valve, visible especially in females. The species was common all through the park occurring at a wide range of altitudes and in different species of bromeliads. This finding is the first freshwater ostracod species described from Honduras and is in agreement with the prediction that the genus Elpidium contains a large number of species with small geographic distributions. We update the list of described species of Elpidium and present a key to species. PMID:23840164

  1. Sedimentary and microfaunal evolution in the Quaternary deposits in El Akarit river mouth (Gulf of Gabes, Tunisia): Paleo-environments and extreme events

    NASA Astrophysics Data System (ADS)

    Ben Rouina, Soumaya; Bassetti, Maria Angela; Touir, Jamel; Trabelsi, Khaled; Berne, Serge

    2016-09-01

    The quantitative study of ostracod and benthic foraminifera assemblages coupled with sedimentary facies, of the AK1 core (6 m-long) retrieved from the El Akarit prodelta (Gulf of Gabes, SE Tunisia) at an elevation of 0 m, enabled us to better understand the dynamics of depositional environments and to identify different stages of the Akarit river mouth evolution. Two major steps were identified: the first (>40,000 yr BP) possibly coincides with the Marine Isotope Stage 5e, onlapping continental Pleistocene deposits. It allowed the settlement of an open lagoon rich in marine microfauna that has become progressively more confined. The second one, late Holocene in age (last 3000 yr BP) is the succession of three extreme events episodes, characterized by very high-energy hydrodynamics and possibly linked to the occurrence of major storms and/or floods.

  2. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  3. Ostracodology-Linking Bio- and Geosciences: Proceedings of the 15th International Symposium on Ostracoda, Berlin, 2005

    NASA Astrophysics Data System (ADS)

    Cronin, Thomas M.

    2008-04-01

    If you want to know about the ``paradox of sex'' or why a tiny crustacean prefers spinach over brussels sprouts, then read this book. Ostracodes are a class of small crustaceans of 33,000 known living and extinct species and many more yet to be described. They are notable for their application to paleoclimatology and paleoenvironmental reconstruction-as described by J. Holmes and A. Chivas in the 2002 AGU Geophysical Monograph Series volume 131. In addition, they can make the evolutionary claim to the oldest proven male animal, a 435-million-year-old Silurian fossil from England called Colymbosathon ecplecticos (D. J. Siveter et al., Science, 302, 1749-1751, 2003).

  4. A new species of Elpidium (Crustacea, Ostracoda) from bromeliads in Cusuco National Park, Honduras.

    PubMed

    Pinto, Ricardo L; Jocqué, Merlijn

    2013-01-01

    Passively dispersing aquatic invertebrates such as Ostracoda in restricted aquatic habitats such as bromeliads remain an intriguing observation considering the highly specialised dispersal vectors needed for efficient colonisation. Here we describe a new species of Elpidium, Elpidium merendonense sp. n., collected from bromeliads in the cloud forest from Cusuco National Park, Honduras. Elpidium merendonense sp. n. is a small to medium-sized species that can be easily distinguished from its congeners by its unique outgrowth at the posterior end of the left valve, visible especially in females. The species was common all through the park occurring at a wide range of altitudes and in different species of bromeliads. This finding is the first freshwater ostracod species described from Honduras and is in agreement with the prediction that the genus Elpidium contains a large number of species with small geographic distributions. We update the list of described species of Elpidium and present a key to species. PMID:23840164

  5. Epizooic metazoan meiobenthos associated with tubeworm and mussel aggregations from cold seeps of the northern Gulf of Mexico.

    PubMed

    Bright, M; Plum, C; Riavitz, L A; Nikolov, N; Martinez Arbizu, P; Cordes, E E; Gollner, S

    2010-11-01

    The abundance and higher taxonomic composition of epizooic metazoan meiobenthic communities associated with mussel and tubeworm aggregations of hydrocarbon seeps at Green Canyon, Atwater Valley, and Alaminos Canyon in depths between 1400 and 2800 m were studied and compared to the infaunal community of non-seep sediments nearby. Epizooic meiofaunal abundances of associated meiobenthos living in tubeworm bushes and mussel beds at seeps were extremely low (usually <100 ind. 10 cm(-2)), similar to epizooic meiofauna at deep-sea hydrothermal vents, and the communities were composed primarily of nematodes, copepods, ostracods, and halacarids. In contrast, epizooic meiobenthic abundance is lower than previous studies have reported for infauna from seep sediments. Interestingly, non-seep sediments contained higher abundances and higher taxonomic diversity than epizooic seep communities, although in situ primary production is restricted to seeps. PMID:21264038

  6. Phytotoxkit® and Ostracodtoxkit® tests for assessing the toxicity of sediment samples with high concentration of heavy metals

    NASA Astrophysics Data System (ADS)

    Garcia-Lorenzo, Maria Luz; Martinez-Sanchez, Maria Jose; Molina, Jose; Hernandez-Cordoba, Manuel

    2010-05-01

    To estimate the risk of contaminants, chemical methods need to be complemented with biological methods. Ecotoxicological testing may be a useful approach for assessing the toxicity as a complement to chemical analysis. The aim of this study was to evaluate the sensitivity and applicability of two bioassays representing multiple trophic levels, for the preliminary ecotoxicological screening of sediments from sites contaminated by mining activities: a chronic toxicity test with the ostracod Heterocypris incongruens and a phytotoxicity test using Lepidium sativum, Sorghum saccharatum and Sinapis alba seeds. For this study, 30 soils samples were collected from the Sierra Minera (Murcia, SE Spain) for general analytical determinations and the total metal content (Pb, Zn, Cd and As) was determined. The Phytotoxkit® test measures the decrease in (or the absence of) seed germination and of the growth of the young roots after 3 days of exposure of seeds of selected higher plants to a contaminated matrix compared with the controls germinated in a reference soil. The plants selected for the Phytotoxkit® microbiotest were: the monocotyl Sorghum saccharatum (Sorgho) and the dicotyls Lepidium sativum (Garden cress) and Sinapis alba (mustard) (Phytotoxkit®, 2004). The percent inhibition of seed germination (SG) and root growth inhibition (RI) for each plant were calculated. Ostracodtoxkit® test consists of placing freshly hatched ostracod neonates in multiwell cups in 2 ml synthetic freshwater, with 300 µl sediment and 3x107 algal cells (Selenastrum capricornutum). After 6 days, incubation at 25 °C in darkness, the mortality of test organisms was determined (Ostracodtoxkit® FTM, 2001) and growth inhibition was calculated. Soil samples showed a mean pH value of 6.0 in water and 5.7 in KCl. The EC varied from 1.0 dS m-1 to 56.2 dS m-1, with a mean value of 17.7 dS m-1. The mean value for Pb was 0.84 mg kg-1, 10593 mg kg-1 for Zn, 23.18 mg kg-1 for Cd and 0.16 mg kg-1 for As

  7. Two new species of Semicytherura (Podocopa: Ostracoda) from Akkeshi Bay, Hokkaido, Japan, with comments on their speciation and related species.

    PubMed

    Yamada, Shinnosuke; Tsukagoshi, Akira

    2010-03-01

    Two new ostracod species, Semicytherura maxima n. sp. and S. ikeyai n. sp., both belonging to the S. henryhowel group of the genus, are described. They were collected from Akkeshi Bay in northeastern Japan, and inhabit the marine sediment surface in places deeper than the intertidal zone. Their distributions in northern Japan seem to be influenced by the cold-water Chishima Current (Oyashio). The geological distribution and species diversity were surveyed for each of the subgroups recognized in the S. henryhowei group. The results suggest that these subgroups split from each other in the NW Pacific by the Early Miocene, and that one of them has spread around the Northern Hemisphere, while the other has remained in the NW Pacific since that time. PMID:20192699

  8. Intertidal meiofauna of Jeju Island, Korea

    NASA Astrophysics Data System (ADS)

    Pavlyuk, Olga N.; Trebukhova, Yulia A.

    2011-03-01

    For the first time, the structure of the meiobenthos community and marine nematodes in particular was investigated in the different intertidal zones of Jeju Island (South Sea of Korea). A relationship was found between the density of meiobenthic communities and the type of the bottom sediment. In addition, in the silty sediments, nematodes were dominant, while in the sandy sediments harpacticoids and ostracods were dominant groups. Sixty eight species belonging to 60 genera and 19 families of nematodes were found in the whole area. Four different nematode taxocenosis were distinguished using a cluster analysis. Dominant feeding groups were omnivores (2B) and epistratum-feeders (2A). The highest number of non-selective deposit-feeders (1B) was detected in the lagoon with the bottom silty sediments.

  9. The aquatic and semiaquatic biota in Miocene amber from the Campo LA Granja mine (Chiapas, Mexico): Paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Serrano-Sánchez, María de Lourdes; Hegna, Thomas A.; Schaaf, Peter; Pérez, Liseth; Centeno-García, Elena; Vega, Francisco J.

    2015-10-01

    Amber from the Campo La Granja mine in Chiapas, Mexico, is distinct from other sources of amber in Chiapas. Campo La Granja amber has distinct layers created by successive flows of resin with thin layers of sand on most surfaces. Aquatic and semi-aquatic arthropods are commonly found. Together these pieces of evidence suggest an estuarine environment similar to modern mangrove communities. The aquatic crustaceans are the most intriguing aspect of the biota. A large number of ostracods have been found in the amber-many with their carapaces open, suggesting that they were alive and submerged in water at the time of entombment. The only known examples of brachyuran crabs preserved in amber are found in the Campo La Granja amber. Amphipods, copepods, isopods, and tanaids are also members of the crustacean fauna preserved in amber.

  10. Climatic and limnologic setting of Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Dean, W.E.; Wurtsbaugh, W.A.; Lamarra, V.A.

    2009-01-01

    Bear Lake is a large alkaline lake on a high plateau on the Utah-Idaho border. The Bear River was partly diverted into the lake in the early twentieth century so that Bear Lake could serve as a reservoir to supply water for hydropower and irrigation downstream, which continues today. The northern Rocky Mountain region is within the belt of the strongest of the westerly winds that transport moisture during the winter and spring over coastal mountain ranges and into the Great Basin and Rocky Mountains. As a result of this dominant winter precipitation pattern, most of the water entering the lake is from snowmelt, but with net evaporation. The dominant solutes in the lake water are Ca 2+, Mg2+, and HCO32-, derived from Paleozoic carbonate rocks in the Bear River Range west of the lake. The lake is saturated with calcite, aragonite, and dolomite at all depths, and produces vast amounts of carbonate minerals. The chemistry of the lake has changed considerably over the past 100 years as a result of the diversion of Bear River. The net effect of the diversion was to dilute the lake water, especially the Mg2+ concentration. Bear Lake is oligotrophic and coprecipitation of phosphate with CaCO3 helps to keep productivity low. However, algal growth is colimited by nitrogen availability. Phytoplankton densities are low, with a mean summer chlorophyll a concentration of 0.4 mg L-1. Phytoplankton are dominated by diatoms, but they have not been studied extensively (but see Moser and Kimball, this volume). Zooplankton densities usually are low (<10 L-1) and highly seasonal, dominated by calanoid copepods and cladocera. Benthic invertebrate densities are extremely low; chironomid larvae are dominant at depths <30 m, and are partially replaced with ostracodes and oligochaetes in deeper water. The ostracode species in water depths >10 m are all endemic. Bear Lake has 13 species of fi sh, four of which are endemic. Copyright ?? 2009 The Geological Society of America.

  11. Correlation of onshore-offshore Oligocene through lower Miocene strata using 87Sr/ 86Sr isotopic ratios, north flank of Cape Fear Arch, North Carolina, USA

    NASA Astrophysics Data System (ADS)

    Harris, W. B.; Mendrick, S.; Fullagar, P. D.

    2000-07-01

    Cores from onshore and offshore of the Onslow block reveal at least three depositional sequences above the Eocene Castle Hayne Limestone and below the Miocene Pungo River Formation. Through use of 87Sr/ 86Sr ratios and their resultant dates, these sequences are correlated from onshore to offshore, thus clarifying the geologic history of the inner continental shelf of North Carolina. The oldest depositional sequence consists of calcareous quartz sand and sandy, pelecypod-mold grainstone updip and yellowish gray, very fine to fine calcareous quartz sand with minor clay and silt downdip. Most of the carbonate in the downdip part of the sequence consists of foraminifers, ostracods, echinoid spines and other small allochems. Eight hand-picked foraminiferal samples, including two replicate analyses, from this sequence selected from two onshore cores and one offshore core yield 87Sr/ 86Sr ratios from 0.707901 to 0.708006 equivalent to LOWESS (Locally Weighted Regression Scatterplot Smoother) dates ranging from 29.2 to 32.0 Ma. This indicates this sequence is Rupelian (early Oligocene) in age and assignable to either the TA4.4 or TA4.5 global coastal onlap cycle. The youngest sequence consists of oyster-bearing quartz sand and laterally equivalent clay with mollusks onshore and very fine to fine calcareous quartz sand offshore. Twelve foraminiferal and one ostracod sample, including five replicate analyses, from three cores on the inner shelf of Onslow Bay yield 87Sr/ 86Sr ratios from 0.708332 to 0.708386 equivalent to LOWESS dates ranging from 21.1 to 22.2 Ma. This indicates the sequence is Aquitanian (early Miocene) in age and assignable to the TB1.4 global coastal onlap cycle. Although Chattian (late Oligocene) sequences are recognized onshore in outcrop and core and are projected to continue into Onslow Bay, no cores provided Sr samples for analysis interpreted to be late Oligocene in age.

  12. Influence of UV radiation on four freshwater invertebrates.

    PubMed

    Cywinska, A; Crump, D; Lean, D

    2000-11-01

    Laboratory tests confirmed a negative and variable response of the following four species to artificial UV radiation: Cypridopsis vidua, an ostracode; Chironomus riparius, a midge larvae; Hyalella azteca, an amphipod; and Daphnia magna, a daphnid. Severe damage occurred at UV-B irradiance ranging from 50 to 80% of incident summer values. Under constant exposure to UV and photosynthetically active radiation (PAR) the acute lethal response was recorded at 0.3, 0.8, 0.8 and 4.9 W m-2 UV-B for D. magna, H. azteca, C. riparius and C. vidua, respectively. Sublethal UV-B damage to invertebrates included impaired movement, partial paralysis, changes in pigmentation and altered water balance (bloating). A series of UV-B, UV-A and PAR treatments, applied separately and in combination, revealed a positive role for both UV-A and PAR in slowing down UV-B damage. Mean lethal concentration values of the species typically more tolerant to UV and PAR (Cypridopsis, Chironomus) decreased conspicuously when both UV-A and PAR were eliminated. For UV-B-sensitive species (Hyalella, Daphnia) these differences were notably smaller. We suggest that this gradation of sensitivity among the tested species demonstrates potential differences in repairing mechanisms which seem to work more efficiently for ostracodes and chironomids than for amphipods and daphnids. Manipulations with a cellulose acetate filter showed that lower range UV-B (280-290 nm), produced by FS-40 lamps, may cause excessive UV damage to invertebrates. PMID:11107851

  13. Taphonomic and paleoenvironmental inferences from a cephalopod shell-bank occurrence, Mississippian Slade Formation, northeastern Kentucky

    SciTech Connect

    Mason, C.E. . Dept. of Physical Sciences); Ettensohn, F.R. . Dept. of Geological Sciences)

    1994-04-01

    A cephalopod fauna containing at least five ammonoid and four neutiloid species represents a unique taphonomic, shell-bank occurrence from the Holly fork and Tygarts Creek members of the Slade Formation along Interstate 64 in Rowan County, northeastern Kentucky. The cephalopod life modes are not consistent with interpreted depositional environments of the lithologies in which they are found; nor are they consistent with life modes of other fauna in the rocks. For example, Holly Fork specimens were found in birdseye calcilutites with algal laminae, deolomitic intraclasts, mudcracks, and a restricted fauna of high-spired gastropods and ostracodes. Specimens from the overlying Tygarts Creek Member are from crossbedded oolitic calcarenites with large, rounded intraclasts and a sparse, thick-shelled fauna of straperolid gastropods and stemless crinoids. Stratigraphic and sedimentological analyses of these units indicates that the Tygarts Creek represents a carbonate-sandbelt or beach-ridge deposit behind which Holly Fork tidal flats developed. Shell-bank deposits in the Holly Fork represent taphocoenoses composed of allochthonous cephalopods and autochthonous gastropods and ostracods; mollusc specimens are preserved by grain-growth patterns of recrystallization. Complete growth series of some cephalopod species are present, but it is doubtful that all species lived together. Preservation ranges from slightly abraded intact individuals to fragmentary shattered individuals; there appears to be no preferential orientation of specimens. The unnatural occurrence of this open-marine cephalopod fauna in a tidal-flat setting probably resulted from sedimentological concentration during a storm event. The exact cause of cephalopod mortality is unknown, but die-off after mating can be eliminated due to presence of many sexually immature individuals and the diversity of cephalopods present.

  14. Mediterranean-Paratethys connectivity during the Messinian salinity crisis: The Pontian of Azerbaijan

    NASA Astrophysics Data System (ADS)

    van Baak, Christiaan G. C.; Stoica, Marius; Grothe, Arjen; Aliyeva, Elmira; Krijgsman, Wout

    2016-06-01

    Prior to the onset of the Messinian Salinity Crisis, a connection was established between the Mediterranean Sea and the Paratethys region to the north. Rivers currently draining into the Caspian Sea thereby became important for the Mediterranean hydrological budget. The role of this connection and the influence of the Paratethys on the hydrological budget of the Mediterranean Sea during the Messinian Salinity Crisis is however poorly understood because of a lack of records in the Paratethys with a high-resolution (cyclostratigraphic) age model. Here, we present a high-resolution integrated stratigraphic study of a key section in the Caspian Sea region (Azerbaijan), to assess the connectivity of the Caspian Sea during the salinity crisis. The studied section spans the time interval between ~ 6.16 Ma and < 5.38 Ma, and records continuous deposition under brackish-marine conditions. We show the connection between the Mediterranean Sea and the Caspian Sea formed at 6.12 ± 0.02 Ma. Across the onset of the Messinian Salinity Crisis, the studied section changes from anoxic to oxic conditions and an abundant ostracod fauna develops. A sea-level drop in the order of 100-200 m is evident from changes in the ostracod faunal assemblage and is dated at 5.6 Ma. The top of the section marks a second sea-level drop and the complete freshening of the record. The Pontian phase of Mediterranean-Paratethys connectivity represents a maximum size of Paratethys at a time of minimum Atlantic-Mediterranean connectivity. Enhanced Paratethys outflow water at this time likely led to increased stratification and affected the Mediterranean throughout the Messinian Salinity Crisis.

  15. Triassic and Jurassic rocks at Currie, Nevada Preliminary paleontologic evidence

    SciTech Connect

    Johnson, E.A.; Dubiel, R.F.; Brouwers, E.M. ); Litwin, R.J. ); Ash, S.R. ); Good, S.C. )

    1993-04-01

    A sequence of continental rocks overlies the Lower Triassic Thaynes Formation in a poorly exposed syncline near Currie in northeastern NV. The authors recognize four lithostratigraphic units above the Thaynes near Currie and provide new paleontologic data. In ascending order, unit 1 (120 ft) consists of reddish-brown, very fine grained sandstone. Unit 2 (50 ft) consists of light-gray, trough cross-stratified, coarse-grained, conglomeratic sandstone. Unit 3 (at least 500 ft) consists of green, red, and brown sandstone and mudstone. Unit 4 occurs as isolated outcrops of reddish-orange, fine- to medium-grained sandstone. New fossil evidence, while not definitive, constrain the age of this sequence. Plant megafossils in unit 1 include (1) a specimen with narrow ovate leaves, possibly from an early Mesozoic conifer and (2) abundant fragments of probable Neocalamites. The presence of these fossils and the absence of any angiosperm leaves or wood fragments suggest an early Mesozoic age. Ostracodes in unit 3 are exclusively Darwinula sp., and their association with conchostracans in the absence of younger ostracodes suggests a Triassic age. Finally, two small outcrops, previously mapped as Triassic/Jurassic, contain the gastropods Pilidae indet. and Lymnaea sp., which resemble Late Cretaceous to Paleocene faunas. The sequence is similar to the nearest Lower Mesozoic section on the Colorado Plateau at Cove Fort, Utah, 165 miles to the southeast. The authors' new evidence supports the longstanding correlation of units 1--4 with the Lower Triassic Moenkopi Formation (part), the Shinarump and Petrified Forest Members of the Upper Triassic Chinle Formation, and the Lower Jurassic Navajo Sandstone of the Plateau. These rocks at Currie demonstrate that the Early Mesozoic depositional systems of the Colorado Plateau extended at least this far west and provide constraints on Early Mesozoic tectonism in the eastern Great Basin.

  16. Orbital forcing of deep-sea benthic species diversity

    USGS Publications Warehouse

    Cronin, T. M.; Raymo, M.E.

    1997-01-01

    Explanations for the temporal and spatial patterns of species biodiversity focus on stability-time, disturbance-mosaic (biogenic microhabitat heterogeneity) and competition-predation (biotic interactions) hypotheses. The stability-time hypothesis holds that high species diversity in the deep sea and in the tropics reflects long-term climatic stability. But the influence of climate change on deep-sea diversity has not been studied and recent evidence suggests that deep-sea environments undergo changes in climatically driven temperature and flux of nutrients and organic-carbon during glacial-interglacial cycles. Here we show that Pliocene (2.85-2.40 Myr) deep-sea North Atlantic benthic ostracod (Crustacea) species diversity is related to solar insolation changes caused by 41,000-yr cycles of Earth's obliquity (tilt). Temporal changes in diversity, as measured by the Shannon- Weiner index, H(S), correlate with independent climate indicators of benthic foraminiferal oxygen-isotope ratios (mainly ice volume) and ostracod Mg:Ca ratios (bottomwater temperature). During glacial periods, H(S) = 0.2-0.6, whereas during interglacials, H(S) = 1.2-1.6, which is three to four times as high. The control of deep-sea benthic diversity by cyclic climate change at timescales of 103-104 yr does not support the stability-time hypothesis because it shows that the deep sea is a temporally dynamic environment. Diversity oscillations reflect large-scale response of the benthic community to climatically driven changes in either thermohaline circulation, bottom temperature (or temperature-related factors) and food, and a coupling of benthic diversity to surface productivity.

  17. Earth-System Scales of Biodiversity Variability in Shallow Continental Margin Seafloor Ecosystems

    NASA Astrophysics Data System (ADS)

    Moffitt, S. E.; White, S. M.; Hill, T. M.; Kennett, J.

    2015-12-01

    High-resolution paleoceanographic sedimentary sequences allow for the description of ecosystem sensitivity to earth-system scales of climate and oceanographic change. Such archives from Santa Barbara Basin, California record the ecological consequences to seafloor ecosystems of climate-forced shifts in the California Current Oxygen Minimum Zone (OMZ). Here we use core MV0508-20JPC dated to 735,000±5,000 years ago (Marine Isotope Stage 18) as a "floating window" of millennial-scale ecological variability. For this investigation, previously published archives of planktonic δ18O (Globigerina bulloides) record stadial and interstadial oscillations in surface ocean temperature. Core MV0508-20JPC is an intermittently laminated archive, strongly influenced by the California Current OMZ, with continuously preserved benthic foraminifera and discontinuously preserved micro-invertebrates, including ophiuroids, echinoderms, ostracods, gastropods, bivalves and scaphopods. Multivariate statistical approaches, such as ordinations and cluster analyses, describe climate-driven changes in both foraminiferal and micro-invertebrate assemblages. Statistical ordinations illustrate that the shallow continental margin seafloor underwent predictable phase-shifts in oxygenation and biodiversity across stadial and interstadial events. A narrow suite of severely hypoxic taxa characterized foraminiferal communities from laminated intervals, including Bolivina tumida, Globobulimina spp., and Nonionella stella. Foraminiferal communities from bioturbated intervals are diverse and >60% similar to each other, and they are associated with echinoderm, ostracod and mollusc fossils. As with climate shifts in the latest Quaternary, there is a sensitive benthic ecosystem response in mid-Pleistocene continental margins to climatically related changes in OMZ strength.

  18. Stetson Pit, Dare County, North Carolina: An integrated chronologic, faunal, and floral record of subsurface coastal quaternary sediments

    USGS Publications Warehouse

    York, L.L.; Wehmiller, J. F.; Cronin, T. M.; Ager, T.A.

    1989-01-01

    Continuous split spoon samples from a drill hole penetrating 34 m of coastal plain sediments at Stetson Pit in Dare County, North Carolina were taken for lithologic, aminostratigraphic, faunal (ostracodes) and floral (pollen) analyses. Three distinct aminozones are recognized in the subsurface section based upon D-alloisoleucine/L-isoleucine (A/I) values in each of the molluscan species Mulinia lateralis and Mercenaria sp. Ostracode zonations in the subsurface section are based on percentages of 80 thermophilic and cryophilic species (those living today south and north of Cape Hatteras) and the percentages of brackish water species. Five assemblage zones are delineated. Six pollen assemblage zones are also delineated within the subsurface section based upon study of 48 sediment samples. The subsurface record at Stetson Pit is interpreted to represent portions of four interglacials based upon the combined faunal, floral and aminostratigraphic data. The two younger aminozones, with amino acid age estimates of 100,000??20,000 yr (-7.2 to -11.2 m MSL) and 300,000-500,000 yr (-13 to -14.2 m MSL), represent portions of middle/late Pleistocene interglacials. The lower aminozone (-17.4 to -33 m MSL) spans an interval that probably includes at least two interglacials (based upon faunal and floral records) and has an age estimated to be between 800,000 and 1,300,000 yr. Boundaries delineated by faunal, floral, and amino acid methods do not always coincide, due to sampling constraints and phase lags between the different records. One major unconformity (at -17.4 m MSL) in the Stetson Pit section is easily recognized from lithologic characteristics and may represent a hiatus of as much as 800,000 yr. Lithologic changes associated with all other zone boundaries are subtle and would probably not be considered significant in the absence of faunal, floral, or amino acid data. ?? 1989.

  19. A Biota Associated with Matuyama-Age Sediments in West-Central Illinois

    NASA Astrophysics Data System (ADS)

    Miller, Barry B.; Graham, Russell W.; Morgan, Alan V.; Miller, Norton G.; McCoy, William D.; Palmer, Donald F.; Smith, Alison J.; Pilny, J. J.

    1994-05-01

    A fossil assemblage containing molluscs, mammals, insects, ostracodes, and plants has been recovered from a silt-filled depression near Lima, in west-central Illinois. The reversed remanent magnetic signature of the sediments and the temporal ranges of two mammals, Microtus paroperarius and Lasiopodomys deceitensis, constrain the age of the assemblage to between 730,000 and 830,000 yr B.P. The extent of isoleucine epimerization in the molluscan shell is consistent with this age interpretation. The fauna includes at least 43 taxa of beetles from 11 families, 35 nominal species of molluscs, and two genera of ostracodes. The mammals include two shrews, three rodents, and a rabbit. The plant macrofossils (no pollen recovered) include 25 species of seed plants and four kinds of terrestrial or wetland mosses. Most of the plant species identified still occur in the upper Midwest, although a few of the taxa are found mainly to the north of the site. The fauna is characterized by an almost total absence of true aquatic taxa. The association of both boreal and thermophilous faunal and floral elements suggest that summer temperatures were not greatly different from present ones, but cooler, moist areas must have been available to support the boreal elements. Local conditions were probably similar to those now found in northeastern Iowa, where rains blocks, fissures, and joints in carbonate bedrock serve as traps for debris accumulations, provide shade, and are kept cool and moist during the hot summer months by cold-air drainage and groundwater seepage. Summer mean temperature in these microhabitats was probably between 18 and 20°C, similar to temperatures that now occur near the northern hardwood spruce-fir transition in the eastern United States.

  20. Identification and characterisation of hemocyanin of the fish louse Argulus (Crustacea: Branchiura).

    PubMed

    Pinnow, Pauline; Fabrizius, Andrej; Pick, Christian; Burmester, Thorsten

    2016-02-01

    Hemocyanin transports oxygen in the hemolymph of many arthropod species. Within the crustaceans, this copper-containing protein was thought to be restricted to Malacostraca, while other crustacean classes were assumed to employ hemoglobin or lack any respiratory protein. Only recently it has become evident that hemocyanins also occur in Remipedia and Ostracoda. Here we report for the first time the identification and characterisation of hemocyanin in the fish louse Argulus, which belongs to the class of Branchiura. This finding indicates that hemocyanin was the principal oxygen carrier in the stem lineage of the pancrustaceans, but has been lost independently multiple times in crustacean taxa. We obtained the full-length cDNA sequences of two hemocyanin subunits of Argulus foliaceus by a combination of RT-PCR, RACE and Illumina sequencing of the transcriptome. In addition, one full-length and one partial cDNA sequence were derived from the transcriptome data of Argulus siamensis. Western blot analysis confirmed the presence of at least two hemocyanin subunits in A. foliaceus, which are expressed at the mRNA level at a 1:3.5 ratio. The addition to the branchiuran hemocyanin subunits to a multiple sequence alignment of arthropod, hemocyanins improved the phylogenetic resolution within the pancrustacean hemocyanins. Malacostracan, ostracod and branchiuran hemocyanins are distinct from the hexapod and remipede hemocyanins, reinforcing the hypothesis of a close relationship of Remipedia and Hexapoda. Notably, the ostracod hemocyanins are paraphyletic with respect to the branchiuran hemocyanins, indicating ancient divergence and differential loss of distinct subunit types. PMID:26515963

  1. A magnetostratigraphic time frame for Plio-Pleistocene transgressions in the South Caspian Basin, Azerbaijan

    NASA Astrophysics Data System (ADS)

    Van Baak, C. G. C.; Vasiliev, I.; Stoica, M.; Kuiper, K. F.; Forte, A. M.; Aliyeva, E.; Krijgsman, W.

    2013-04-01

    The isolation of the Caspian Sea took place in the latest Miocene coinciding with a significant lowering of sea level and the deposition of a massive lowstand deltaic system. This so-called Productive Series is the main reservoir unit of the South Caspian oil-province. The Productive Series is overlain by marine clays from the Akchagylian and Apsheronian regional stages. During the Plio-Pleistocene, the Caspian basin experienced several short periods of intermittent connectivity with other marine basins. This work aims to create integrated, high-resolution, bio-magnetostratigraphic dating of these regional transgressions in key sections of the South Caspian Basin in Azerbaijan. We sample two long sections, the Lokbatan section in the Palaeo-Volga delta and the Xocashen section in the Kura Basin. Palaeoenvironmental reconstructions are derived from characteristic ostracod species. Rock magnetic analyses combined with thermal demagnetisation data indicate that the magnetic signal is carried dominantly by the iron oxide magnetite in the Productive Series of Lokbatan section and in the Xocashen section. The marine Akchagylian and Apsheronian of Lokbatan are characterised by the iron sulphide greigite, which appears to be of (near-) primary origin. The most logical correlation of the magnetic polarity patterns to the Geomagnetic Polarity Time Scale dates the Akchagylian transgression at ~ 3.2 Ma, a major transgression during the Apsheronian at ~ 2.0 Ma and the Bakunian transgression at 0.85-0.89 Ma. Ostracod assemblages indicate increasing salinities during these transgressions, from fresh water lacustrine to brackish-marine species. This implies that marine connections have been created with an adjacent basin that has a higher salinity, most likely the Black Sea.

  2. Multiproxy evidence of Holocene climate variability from estuarine sediments, eastern North America

    USGS Publications Warehouse

    Cronin, T. M.; Thunell, R.; Dwyer, G.S.; Saenger, C.; Mann, M.E.; Vann, C.; Seal, R.R.

    2005-01-01

    We reconstructed paleoclimate patterns from oxygen and carbon isotope records from the fossil estuarine benthic foraminifera Elphidium and Mg/ Ca ratios from the ostracode Loxoconcha from sediment cores from Chesapeake Bay to examine the Holocene evolution of North Atlantic Oscillation (NAO)-type climate variability. Precipitation-driven river discharge and regional temperature variability are the primary influences on Chesapeake Bay salinity and water temperature, respectively. We first calibrated modern ??18 Owater to salinity and applied this relationship to calculate trends in paleosalinity from the ??18 Oforam, correcting for changes in water temperature estimated from ostracode Mg /Ca ratios. The results indicate a much drier early Holocene in which mean paleosalinity was ???28 ppt in the northern bay, falling ???25% to ???20 ppt during the late Holocene. Early Holocene Mg/Ca-derived temperatures varied in a relatively narrow range of 13?? to 16??C with a mean temperature of 14.2??C and excursions above 16??C; the late Holocene was on average cooler (mean temperature of 12.8??C). In addition to the large contrast between early and late Holocene regional climate conditions, multidecadal (20-40 years) salinity and temperature variability is an inherent part of the region's climate during both the early and late Holocene, including the Medieval Warm Period and Little Ice Age. These patterns are similar to those observed during the twentieth century caused by NAO-related processes. Comparison of the midlatitude Chesapeake Bay salinity record with tropical climate records of Intertropical Convergence Zone fluctuations inferred from the Cariaco Basin titanium record suggests an anticorrelation between precipitation in the two regions at both millennial and centennial timescales. Copyright 2005 by the American Geophysical Union.

  3. Palaeoenvironmental reconstruction from Lake Iznik (W Turkey) and Üçaǧizli Cave (S Turkey) - implications for human dispersal in the Upper Palaeolithic along coastal Anatolia.

    NASA Astrophysics Data System (ADS)

    Viehberg, Finn A.; Assanov, Sergey; Kuhn, Steven; Reed, Jane; Ülgen, Umut B.; Namık Çaǧatay, M.; Melles, Martin

    2013-04-01

    Transcontinental dispersal of modern humans from the Near East to the Balkans in the Middle and Upper Palaeolithic is expected to have followed the coastline (i.e., Yarımburgaz, Karain and Üçaǧızlı caves). Lake Iznik is situated 80 km south of the Bosphorus (Western Turkey) close to the Marmara Sea. Here we retrieved a continuous sediment record covering the past ~40 ka cal BP. A multiproxy approach enabled us to reconstruct the environmental history. We included biological proxies i.e., diatoms, cladocerans and ostracods as biological proxies, but also physical and geochemical proxies were analysed. Geomorphological findings in the lake basin and geochemical analyses hint to changing lake water levels at least since 40 ka cal BP that lasted until c. 11 cal. kyr BP. This supports the theory of persisting dry climate conditions before the onset of the Holocene also inferred from geochemical sediment proxies (i.e., element analysis), diatoms and ostracod shell chemistry. The Upper Palaeolithic sequences (45-33 ka cal BP) at the Üçaǧızlı Cave (Hatay) yield clear evidence of the technological transition between Initial Upper Palaeolithic and Ahmarian, but also documents major shifts in diet of past hunting community. The identified animal remains in the cave sequence change from larger ungulates to smaller ungulates and increase in fish and shellfish. It is proposed that the compositional change in game is not solitarily caused by technology advances, but also by environmental and climatic changes as inferred from sediment archives of Lake Iznik.

  4. Paleontological records indicate the occurrence of open woodlands in a dry inland climate at the present-day Arctic coast in western Beringia during the Last Interglacial

    NASA Astrophysics Data System (ADS)

    Kienast, Frank; Wetterich, Sebastian; Kuzmina, Svetlana; Schirrmeister, Lutz; Andreev, Andrei A.; Tarasov, Pavel; Nazarova, Larisa; Kossler, Annette; Frolova, Larisa; Kunitsky, Viktor V.

    2011-08-01

    Permafrost records, accessible at outcrops along the coast of Oyogos Yar at the Dmitry Laptev Strait, NE-Siberia, provide unique insights into the environmental history of Western Beringia during the Last Interglacial. The remains of terrestrial and freshwater organisms, including plants, coleopterans, chironomids, cladocerans, ostracods and molluscs, have been preserved in the frozen deposits of a shallow paleo-lake and indicate a boreal climate at the present-day arctic mainland coast during the Last Interglacial. Terrestrial beetle and plant remains suggest the former existence of open forest-tundra with larch ( Larix dahurica), tree alder ( Alnus incana), birch and alder shrubs ( Duschekia fruticosa, Betula fruticosa, Betula divaricata, Betula nana), interspersed with patches of steppe and meadows. Consequently, the tree line was shifted to at least 270 km north of its current position. Aquatic organisms, such as chironomids, cladocerans, ostracods, molluscs and hydrophytes, indicate the formation of a shallow lake as the result of thermokarst processes. Steppe plants and beetles suggest low net precipitation. Littoral pioneer plants and chironomids indicate intense lake level fluctuations due to high evaporation. Many of the organisms are thermophilous, indicating a mean air temperature of the warmest month that was greater than 13 °C, which is above the minimum requirements for tree growth. These temperatures are in contrast to the modern values of less than 4 °C in the study area. The terrestrial and freshwater organism remains were found at a coastal exposure that was only 3.5 m above sea level and in a position where they should have been under sea during the Last Interglacial when the global sea level was 6-10 m higher than the current levels. The results suggest that during the last warm stage, the site was inland, and its modern coastal situation is the result of tectonic subsidence.

  5. Reconstruction of Holocene Climate Variability within the Central Mediterranean Using Lake Sediments from the Akrotiri Peninsula, Crete

    NASA Astrophysics Data System (ADS)

    Magill, C. R.; Rosenmeier, M. F.; Cavallari, B. J.; Curtis, J. H.; Weiss, H.

    2005-12-01

    Middle and late Holocene geochemical records from the Limnes depression, a small sinkhole located within the Akrotiri Peninsula, Crete, document centennial and millennial-scale climate variability within the central Mediterranean region. The oldest sediments of the basin consist largely of fibrous plant macrofossils and organic matter and likely indicate lake filling and expansion of wetland vegetation beginning ~5700 radiocarbon years before present (14C-yrs B.P.) (4550 B.C.). The basal peat layers grade into predominantly open water and less shallow lacustrine deposits by 4500 14C-yrs B.P (3200 B.C.). Continuous open water sedimentation within the Limnes core is interrupted by a number of distinct lag deposits and peaty deposits centered at 3700, 1600, and 350 14C-yrs B.P (2100 B.C., 500 A.D., and 1500 A.D.) indicating periods of significantly lowered lake level or perhaps lake desiccation. These ages coincide roughly with oxygen isotope (δ18O) minima measured in biogenic carbonates (ostracod shells) and support the inference for low lake stage. Trace element (Ca, Mg, and Sr) concentrations in ostracod shells from the Limnes core parallel the oxygen isotope record, suggesting that the data reflect basin hydrology rather than changes in the isotopic composition of rainfall. Furthermore, covariance in both δ18O and Mg concentrations eliminate temperature as a control on the oxygen isotope record. Sediments from the basin also contain aragonite remains of the green alga Chara and isotope analysis of the calcite may record additional paleoenvironmental information. The paleoclimate history inferred from the Limnes record correlates temporally (albeit tenuously) to previous paleoenvironmental data that document abrupt onset of arid conditions in the eastern Mediterranean and western Asia ca. 2200 B.C. Moreover, stratigraphic and geochemical evidence of low lake level (drying) within the Limnes basin at 2100 B.C. may correspond to the termination of the Early Minoan

  6. Centennial eolian cyclicity in the Great Plains, USA: A dominant pattern of wind transport over the past 4000 years?

    USGS Publications Warehouse

    Schwalb, Antje; Dean, Walter E.; Fritz, C. Sherilyn; Geiss, Christoph E.; Kromer, Bernd

    2010-01-01

    Proxy evidence at decadal resolution from Late Holocene sediments from Pickerel Lake, northeastern South Dakota, shows distinct centennial cycles (400-700 years) in magnetic susceptibility; contents of carbonate, organic carbon, and major elements; abundance in ostracodes; and delta18O and delta13C values in calcite. Proxies indicate cyclic changes in eolian input, productivity, and temperature. Maxima in magnetic susceptibility are accompanied by maxima in aluminum and iron mass accumulation rates (MARs), and in abundances of the ostracode Fabaeformiscandona rawsoni. This indicates variable windy, and dry conditions with westerly wind dominance, including during the Medieval Climate Anomaly. Maxima in carbonates, organic carbon, phosphorous, and high delta13C values of endogenic calcite indicate moister and less windy periods with increased lake productivity, including during the Little Ice Age, and alternate with maxima of eolian transport. Times of the Maunder, Sporer and Wolf sunspot minima are characterized by maxima in delta18O values and aluminum MARs, and minima in delta13C values and organic carbon content. We interpret these lake conditions during sunspot minima to indicate decreases in lake surface water temperatures of up to 4-5 degrees C associated with decreases in epilimnetic productivity during summer. We propose that the centennial cycles are triggered by solar activity, originate in the tropical Pacific, and their onset during the Late Holocene is associated with insolation conditions driven by precession. The cyclic pattern is transmitted from the tropical Pacific into the atmosphere and transported by westerly winds into the North Atlantic realm where they strengthen the Atlantic Meridional Overturning Circulation during periods of northern Great Plains wind maxima. This consequently leads to moister climates in Central and Northern Europe. Thus, Pickerel Lake provides evidence for mechanisms of teleconnections including an atmospheric link

  7. Microfacies analysis and paleoenvironmental significance of palustrine carbonates in the Thakkhola-Mustang Graben (Nepal Himalaya)

    NASA Astrophysics Data System (ADS)

    Adhikari, Basanta Raj; Wagreich, Michael

    2013-11-01

    The Thakkhola-Mustang Graben represents the extensional tectonic phase of the Tibetan Plateau uplift and whole Himalayan orogeny. It is situated at the northern side of the Dhaulagiri and Annapurna Ranges and south of the Yarlang Tsangpo Suture Zone. Stratigraphically, the oldest sedimentary units are the Tetang and Thakkhola Formations (Miocene), while the Sammargaon, Marpha and Kaligandaki Formations lying disconformably above these formations represent Plio-Pleistocene units. In this study, different lacustrine carbonates and calcretes were investigated within different lithological units and depositional environments to interpret the palaeoenvironmental and palaeoclimatological evolution of the area. Geological mapping, construction of columnar sections and carbonate sampling were carried out in the field, and stable oxygen and carbon isotope analyses and thin section analyses were done in the laboratory. Lacustrine facies contained abundant pelletal, charophytic algae, oncolitic algal micritic palustrine limestones with ostracods, and micritic mudstones with root traces. Stable carbon and oxygen isotope analysis from the carbonates show a range of δ13C values from -0.6‰ to 11.1‰ (V-PDB) and δ18O values from -13.5‰ to -25‰ (V-PDB). Discontinuous growth of oncolites and spherical pellets (25-40 μm in diameter) in micritic limestone, algal mats and charophyte algae indicate the presence of both shallow and deep water carbonates. Ostracods in dark micritic carbonates indicate quiet and calm water conditions. Microfabrics of the carbonates suggest that they were deposited in a flat and shallow lacustrine environment. The δ18O values of the investigated limestones of the Thakkhola-Mustang Graben suggest that it attained the current elevation level prior to the east-west extension of the Himalaya.

  8. Trace metals and persistent organic pollutants in sediments from river-reservoir systems in Democratic Republic of Congo (DRC): Spatial distribution and potential ecotoxicological effects.

    PubMed

    Mwanamoki, Paola M; Devarajan, Naresh; Thevenon, Florian; Birane, Niane; de Alencastro, Luiz Felippe; Grandjean, Dominique; Mpiana, Pius T; Prabakar, Kandasamy; Mubedi, Josué I; Kabele, Christophe G; Wildi, Walter; Poté, John

    2014-09-01

    This paper discusses the occurrence and spatial distribution of metals and persistent organic pollutants (POPs: including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), Polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in sediments from a river-reservoir system. Surface sediments were sampled from thirteen sites of the Congo River Basin and Lake Ma Vallée, both situated in the vicinity of the capital city Kinshasa (Congo Democratic Republic). Sediment qualities were evaluated using toxicity test based on exposing Ostracods to the sediment samples. The highest metal concentrations were observed in sediments subjected to anthropogenic influences, urban runoff and domestic and industrial wastewaters, discharge into the Congo River basin. Ostracods exposed to the sediments resulted in 100% mortality rates after 6d of incubation, indicating the ultimate toxicity of these sediments as well as potential environmental risks. The POPs and PAHs levels in all sediment samples were low, with maximum concentration found in the sediments (area of pool Malebo): OCP value ranged from 0.02 to 2.50 with ∑OCPs: 3.3μgkg(-1); PCB ranged from 0.07 to 0.99 with Total PCBs (∑7×4.3): 15.31μgkg(-1); PAH value ranged from 0.12 to 9.39 with ∑PAHs: 63.89μgkg(-1). Our results indicate that the deterioration of urban river-reservoir water quality result mainly from urban stormwater runoff, untreated industrial effluents which discharge into the river-reservoirs, human activities and uncontrolled urbanization. This study represents useful tools incorporated to evaluate sediment quality in river-reservoir systems which can be applied to similar aquatic environments. PMID:24997956

  9. Diet of the eastern mudminnow (Umbra pygmaea DeKay) from two geographically distinct populations within the North American native range

    USGS Publications Warehouse

    Panek, Frank M.; Weis, Judith S.

    2013-01-01

    Umbra pygmaea (Eastern Mudminnow) is a freshwater species common in Atlantic slope coastal lowlands from southern New York to northern Florida and is typical of slow-moving, mud-bottomed, and highly vegetated streams, swamps, and small ponds. We examined its seasonal food habits at the Great Swamp National Wildlife Refuge (NWR), NJ and at the Croatan National Forest, NC. A total of 147 Eastern Mudminnow from 35–112 mm TL and 190 Eastern Mudminnow from 22–89 mm TL were examined from these sites, respectively. At both locations, we found it to be a bottom-feeding generalist that consumes cladocerans, ostracods, chironomid larvae, coleopteran larvae, and other insects and crustaceans. Ostracods were most common in the diet at the Great Swamp NWR and occurred in 62% ± 2.5% of the stomachs with food. At Croatan National Forest, chironomid larvae were most common and occurred in 66.7% ± 15.8% of the stomachs. There were no statistically significant differences in diet composition between the sites during the winter, summer, and fall. However, when compared on an annual basis, Jaccard’s Index (θJ = 0.636, P = 0.05) suggested that the diet at the two study sites was significantly different. While we identified the same major food groups at both locations, the utilization of these food groups varied seasonally. Detritus was a major stomach content at both locations throughout the year. We also documented cannibalism during the summer season at both locations. The seasonal diet of the Eastern Mudminnow was similar to that of Umbra limi (Central Mudminnow) and Umbra krameri (European Mudminnow). Our findings here are the first quantitative examinations of seasonal differences in the diet of the Eastern Mudminnow within its native North American range.

  10. K-Ar ages confirm Pliocene age for oldest Neogene marine strata near Loreto, Baja California Sur, Mexico

    SciTech Connect

    McLean, H.

    1987-05-01

    Beds of pumiceous tuff interbedded with mollusk-rich sedimentary rocks provide new age constraints on the timing of the late Neogene subsidence and marine transgression a few kilometers north of Loreto, Baja California Sur, Mexico. The lower part of the Neogene section consists of approximately 1500 m of early to middle Miocene nonmarine volcanic-derived sandstone, breccia, and porphyritic andesite and dacite lavas, called the Comondu Formation or Comondu Group by previous workers. The Miocene rocks are unconformably overlain by nearly 1000 m of predominantly marine sandstone, siltstone, conglomerate, coquina, and tuff of Pliocene age. This 1000-m section grades upward from unfossiliferous fanglomerate, sandstone, and pelitic red beds that are interpreted to be nonmarine into mollusk-rich marine strata; this sequence indicates that marine transgression occurred within the Pliocene section. Plagioclase and hornblende from three pumiceous tuff beds stratigraphically located near the base, middle, and top of the marine section yield K-Ar ages of 3.2, 1.9, and 1.8 Ma, respectively; these ages are similar to Pliocene ages indicated by reconnaissance studies of ostracods, diatoms, and foraminifers. The diatoms indicate open-ocean waters and the foraminifers indicate outer shelf depth. Ostracods, oysters, pectens, and other fossil bivalves seem to indicate a shallow-water embayment. Lateral distribution of nonmarine and marine facies suggests a paleoenvironment in which alluvial fans fed coarse debris into a series of coastal fan deltas. The Pliocene basin may have been a largely landlocked embayment similar to the modern Bahia Concepcion, located 70 km north of Loreto. Marine and volcanic rocks are assumed to be associated with the opening of the Gulf of California. If this assumption is correct, the beds near Loreto suggest that the opening occurred during the Pliocene.

  11. A global evaluation of temperature and carbonate ion control on Mg/Ca ratios of ostracoda genus Krithe

    NASA Astrophysics Data System (ADS)

    Elmore, A. C.; Sosdian, S.; Rosenthal, Y.; Wright, J. D.

    2012-09-01

    Improving estimates of past ocean temperatures is paramount to our understanding of ocean circulation and its role in climate change. Magnesium/calcium (Mg/Ca) ratios of carapaces of the benthic ostracod genus Krithe were determined from new, globally distributed core top samples from the Norwegian Sea, Cape Hatteras shelf, Gulf of Mexico, Sulawesi Margin (Indonesia), New Zealand shelf, Ceara Rise, and the North Atlantic. A linear regression of the Krithe Mg/Ca ratios and bottom water temperature (BWT) reveals a significant correlation for locations where temperature during carapace calcification was above ˜3°C, which can be described by the equation Mg/Ca = (0.972 ± 0.152) * BWT + (7.948 ± 1.103) consistent with previous North Atlantic calibrations. Deviations from the global calibration line below ˜3°C follow the same pattern observed for benthic foraminifera, suggesting that the incorporation of magnesium into ostracodal calcite may be secondarily controlled by changes in carbonate ion concentration. Therefore, we propose a linear regression that describes the relationship between magnesium incorporation, temperature, and carbonate saturation for low temperatures (<3°C) Mg/Ca = (0.972 ± 0.152) * BWT + (0.100 ± 0.030) * Δ[CO32-]) + (4.440 ± 1.103) (1 SE = ± 0.3°C). While the standard error of the calibration is small, it requires an accurate knowledge of past Δ[CO32-] concentration, which necessitates additional proxy data. Applying the calibration to glacial samples from the deep North Atlantic Ocean we show that estimates of bottom water temperatures generated from the new Δ[CO32-]- corrected equations are more consistent with results from oxygen isotopes and pore water studies.

  12. Simpson-Arbuckle contact revisited in Northwest Oklahoma County, Oklahoma

    SciTech Connect

    Allison, M.D.; Allen, R.W.

    1995-09-01

    The Joins Formation, the lowermost formation of the Simpson Group, is traditionally the least studied or understood of the Simpson formations. The Joins, not known to produce hydrocarbons in central Oklahoma, is frequently overlooked by those more interested in the productive Simpson formations above and the Arbuckle carbonates below. In a study of the lower Simpson to upper Arbuckle interval in northwestern Oklahoma County, Oklahoma, the Joins Formation was found to be present. The central Oklahoma section consists of interbedded gray, olive gray and green splintery moderately waxy shale, cream to light gray homogeneous microcrystallin dolomite, and microcrystalline to fine crystalline fossiliferous slightly glauconitic well cemented sandstones are also noted. The entire Joins Formation is moderately to very fossiliferous; primarily consisting of crinoids, ostracods, brachiopods, and trilobites. The ostracod fauna closely resembles and correlates with the Arbuckle Mountain section, which has been extensively studied over the years by such authors as Taff, Ulrich and Harris. Beneath the Joins in this area is a normal section of Arbuckle dolomites. Due to the absence of a basal sand in the Joins the separation of the Joins and Arbuckle, utilizing electric logs only, is frequently tenuous. In comparison with the Arbuckle, the Joins tends to have higher gamma ray and S.P. values. Other tools, such as resistivity, bulk density and photoelectric (PE), are frequently inconclusive. For geologists studying the Simpson-Arbuckle contact in central Oklahoma, the presence or absence of the Joins Formation is best determined through conventional lithologic and palenontologic sample identification techniques. Once this has been done, correlation of electric logs with this type log is possible for the local area.

  13. A half-million-year record of paleoclimate from the Lake Manix Core, Mojave Desert, California

    USGS Publications Warehouse

    Reheis, Marith C.; Bright, Jordon; Lund, Steve P.; Miller, David M.; Skipp, Gary; Fleck, Robert J.

    2012-01-01

    Pluvial lakes in the southwestern U.S. responded sensitively to past climate through effects on rainfall, runoff, and evaporation. Although most studies agree that pluvial lakes in the southwestern U.S. reached their highest levels coeval with glacial stages, the specific timing of increased effective moisture and lake-level rise is debated, particularly for the southwesternmost lakes. We obtained a 45-m core of lacustrine sediment from Lake Manix, the former terminus of the Mojave River prior to about 25 ka, and supplemented data from the core with outcrop studies. These sediments provide a robust record of Mojave River discharge over the last half-million years. Lake Manix persisted from OIS 12 through early OIS 2, including during interstadial OIS 3 and interglacials OIS 5, 7, and 9. The ostracode faunal record displays a shift from an unexpectedly warm, summer-dominated lake hydrology during OIS 12 to predominantly colder, winter-dominated conditions afterwards. The ostracode-based stable isotope record displays a large degree of intra-sample variability and does not mimic other well-known isotopic records of climate change. Evaporation likely buffered the Manix δ18O record from most of the expected isotopic differences between interglacial and glacial-interval discharge. Isotopically depleted and stable lakes occurred only four to six times, most notably during OIS 7 and OIS 9. Internal drainage-basin changes also affected the isotopic record. Persistence of lakes in the Manix basin during interglacials requires atmospheric or oceanic circulation controls on the mean position of the Pacific storm track other than large ice sheets. We propose that the relative strength and sign of the Northern Annular Mode (NAM) and its influence on atmospheric river-derived precipitation is a potential explanation.

  14. Deep-sea sampling on CMarZ cruises in the Atlantic Ocean - an Introduction

    NASA Astrophysics Data System (ADS)

    Wiebe, Peter H.; Bucklin, Ann; Madin, Laurence; Angel, Martin V.; Sutton, Tracey; Pagés, Francesc; Hopcroft, Russell R.; Lindsay, Dhugal

    2010-12-01

    The deep-sea zooplankton assemblage is hypothesized to have high species diversity, with low abundances of each species. However, even rare species may have huge population sizes and play a critical role in the dynamics of deep-sea environments. The Census of Marine Zooplankton (CMarZ) study sought to accurately assess zooplankton diversity in the mesopelagic and bathypelagic zones of the subtropical/tropical of the northwest and eastern sections of the Atlantic Ocean using integrated morphological and molecular analysis of large-volume samples to depths of 5,000 m. The field surveys in April 2006 and November 2007 included scientists and students associated with the CMarZ. The cruise field work entailed at-sea analysis of samples and identification of specimens by expert taxonomists, with at-sea DNA sequencing to determine a barcode (i.e., a short DNA sequence for species recognition) for selected species. Environmental data and zooplankton samples were collected with 1-m 2 and 10-m 2 opening/closing MOCNESS (0-1000 m and 1000-5000 m, respectively), and with either a 0.25-m 2 MOCNESS or a 0.5-m 2 Multi-net above 1000 m. More than 500 species were identified and more than 1000 specimens placed in a queue for barcoding on each cruise; several hundred species were barcoded at sea. For several taxonomic groups, a significant fraction of the region's known species were collected and identified. For example, in the northwest Atlantic 93 of 140 known ostracod species for the Atlantic Ocean were collected, 6 undescribed species were found, and the first DNA barcode for a planktonic ostracod was obtained. The deployment of trawls with fine-mesh nets to sample large volumes at great depths for small zooplankton confirmed that there is considerable species diversity at depth, with more species yet to be discovered.

  15. Benthic faunal assemblages from the Holocene middle shelf of the South Evoikos Gulf, central Greece, and their palaeoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Asimina Louvari, Markella; Tsourou, Theodora; Drinia, Hara; Anastasakis, George

    2013-04-01

    South Evoikos Gulf is an elongate, WNW - ESE trending basin, 60 km long and 15 km wide. Its floor slopes towards the south-east where the basin connects with the Aegean Sea across a 55 m deep sill. The hydrographic network of the area is characterized by Asopos river the small Lilas River and some other ephemeral streams. A sedimentary record spanning the last 13000 calyr BP was recovered at N 38°12'23.1228" E 24°8'14.2404", water depth 70 m, in this gulf. A total of 52 samples from the lower half of the core were quantitatively analyzed for micropalaeontological (benthic foraminifera and ostracods) study in order to reconstruct palaeoenvironmental conditions. This work contributes to the evaluation of the modern environmental problems in South Evoikos Gulf (hypoxia, ecosystem changes, subaquatic vegetation die-off, metal pollution) within the context of the palaeoenvironmental record. In the investigated core, the benthic microfaunal assemblages indicate a marine coastal environment with a gradual transition from a circalittoral to an infralittoral restricted environment. The basal part of the record is characterized by Haynesina depressula Assemblage, which is composed of Haynesina depressula, Textularia agglutinans and Bulimina aculeata.The abundance of Haynesina depressula could be associated with normal marine conditions, but always with periodic brackish water influence. The species composed this assemblage, which are almost all typically infaunal, characterize sediments with a high or medium-high muddy fraction, rich in organic matter available for the organisms that live within the sediment, and low salinity bottom water. Samples from the upper unit of the core indicate a nearshore, inner-shelf facies less than 50 m deep. Common inner-shelf species in these samples include Ammonia beccarii together with Bulimina marginata (Sgarrella & Moncharmont Zei, 1993). The highest abundance of A. beccarii is found between 15 and 20 m water-depth in samples with

  16. Living and dead benthic foraminiferal assemblages from bathyal environment in the Pontine Archipelago (Tyrrhenian Sea, Italy)

    NASA Astrophysics Data System (ADS)

    Di Bella, Letizia; Frezza, Virgilio; Ingrassia, Michela; Latino Chiocci, Francesco; Martorelli, Eleonora

    2016-04-01

    (0-66.7%), whereas agglutinated foraminifera are substantially absent. Biloculinella depressa, Biloculinella labiata, Miliolinella subrotunda and Quinqueloculina pygmaea are the more abundant species. As regard the dead assemblages, the Faunal Density is really high (1733-6273 specimens/gr). A total of 89 species were classified, with a range of 42-52 species in each core-interval. The α-Fisher index shows values from 14.21 to 22.06 while Shannon index ranges between 2.92-3.31. In the dead assemblage, perforate taxa are very abundant, with percentages between 74.0 and 85.5%. In this case, imperforate (12.3-18.6%) and agglutinated (1.0-7.4%) tests are accessories. Bulimina marginata, Cassidulina carinata, Cassidulina crassa, Globocassidulina subglobosa and Uvigerina mediterranea are the main constituent of benthic assemblage. In conclusion, miliolids dominate in the living assemblages while calcareous perforate taxa are more abundant in the dead assemblages.

  17. An 110 Ma Crocodilian-Bearing Vertebrate Assemblage Preserved Between Basalt Flows on a mid-Pacific Seamount, ODP Site 865, Allison Guyot

    NASA Astrophysics Data System (ADS)

    Firth, J. V.; Yancey, T.; Alvarez-Zarikian, C.

    2006-12-01

    Crocodilian teeth, fish teeth, scales, and bones, and teeth and bones of uncertain affinities occur within a mudstone deposit sandwiched between basalt flows at the base of ODP Hole 865A on Allison Guyot in the middle of the Pacific Ocean. Age control from large benthic foraminifers, Sr-isotope stratigraphy, and radiometric ages of the basalt place the age of this assemblage at 110 \\mp 1.2 Ma, or late Aptian/early Albian. This deposit contains the oldest known crocodilian remains in the Pacific Realm. The vertebrate-bearing interval lies within a 30 cm mudstone unit overlying lithified fossiliferous limestone and underlying fossiliferous clayey limestone. The surface of the lithified limestone contains fish scales, vertebrate teeth and bones, and a carapace of the ostracod Cytherella. The lower 17 cm of mudstone is the prime vertebrate-bearing layer. It has a fining-upwards grain size trend, and an upward increase in dark coloration. The sand sized fraction is primarily pelletal glauconite, pyrite and fish debris. Limestone clasts up to several mm in diameter occur through the lower portion, whereas the higher portion contains sand laminae. A pristine 1 cm long crocodilian tooth, along with several smaller crocodilian teeth from this interval, attest to the presence of a saltwater crocodilian within the lagoon of this drowned mid-Pacific atoll. Common and varied fish teeth include both slender forms for piercing and grasping mobile prey and blunt flat-topped forms for crushing and grinding hard-shelled bottom living organisms such as oysters. The crushing teeth resemble those of the modern Black Drum fish, a bottom feeder common in shallow coastal environments. Abundant fish scales include both heavy phosphatic ganoid scales, a type present on many Mesozoic fish, and thin flexible scales of a type present on most modern fish. Some teeth and bone fragments are currently unidentified, and may represent vertebrates other than fish or crocodilians. No calcareous

  18. A micropalaeontological and palynological insight into Early Carboniferous floodplain environments

    NASA Astrophysics Data System (ADS)

    Bennett, Carys; Kearsey, Timothy; Davies, Sarah; Millward, David; Marshall, John; Reeves, Emma

    2016-04-01

    Romer's Gap, the interval following the end Devonian mass extinction, is traditionally considered to be depauperate in tetrapod and fish fossils. A major research project (TW:eed -Tetrapod World: early evolution and diversification) focusing on the Tournaisian Ballagan Formation of Scotland is investigating how early Carboniferous ecosystems rebuilt following the extinction. A multi-proxy approach, combining sedimentology, micropalaeontology and palynology, is used to investigate the different floodplain environments in which tetrapods, fish, arthropods and molluscs lived. The formation is characterised by an overbank facies association of siltstone, sandstone and palaeosols, interbedded with dolostone and evaporite units, and cut by fluvial sandstone facies associations of fining-upwards conglomerate lags, cross-bedded sandstone and rippled siltstone. Macrofossils are identified from 326 horizons within a 520 metre thick Ballagan Formation field section at Burnmouth, near Berwick-upon-Tweed, Scottish Borders. Common fauna are ostracods, bivalves, arthropods, sarcopterygians, dipnoans, acanthodians, tetrapods and chondrichthyans. Quantitative microfossil picking of the three sedimentary rock types in which tetrapods occur was undertaken to gain further insight into the palaeoecology. The sediments are; 1) laminated grey siltstones, deposited in floodplain lakes; 2) sandy siltstones, grey siltstones with millimetre size clasts. 71% of these beds overlie palaeosols or desiccated surfaces and are formed in small-scale flooding events; 3) conglomerates, mostly lags at the base of thick sandstones, with centimetre sized siltstone, sandstone and dolostone clasts. Grey siltstones contain a microfauna of common plant fragments, megaspores and sparse actinopterygian and rhizodont fragments. Sandy siltstones have the highest fossil diversity and contain microfossil fragments of plants, megaspores, charcoal, ostracods, actinopterygians, rhizodonts, eurypterids and rarer non

  19. Lakes of the Huron basin: their record of runoff from the laurentide ice sheet

    NASA Astrophysics Data System (ADS)

    Michael Lewis, C. F.; Moore, Theodore C.; Rea, David K.; Dettman, David L.; Smith, Alison M.; Mayer, Larry A.

    The 189,000 km2 Huron basin is central in the catchment area of the present Laurentian Great Lakes that now drain via the St. Lawrence River to the North Atlantic Ocean. During deglaciation from 21-7.5 ka BP, and owing to the interactions of ice margin positions, crustal rebound and regional topography, this basin was much more widely connected hydrologically, draining by various routes to the Gulf of Mexico and Atlantic Ocean, and receiving overflows from lakes impounded north and west of the Great Lakes-Hudson Bay drainage divide. Early ice-marginal lakes formed by impoundment between the Laurentide Ice Sheet and the southern margin of the basin during recessions to interstadial positions at 15.5 and 13.2 ka BP. In each of these recessions, lake drainage was initially southward to the Mississippi River and Gulf of Mexico. In the first recession, drainage subsequently switched eastward along the ice margin to the North Atlantic Ocean. In the second recession, drainage continued southward through the Michigan basin, and later, eastward via the Ontario basin and Mohawk River valley to the North Atlantic Ocean. During the final retreat of ice in the Huron basin from 13 to 10 ka BP, proglacial lake drainage switched twice from the Michigan basin and the Mississippi River system to the North Atlantic via the Ontario basin and Mohawk River valley, finally diverting to the Champlain Sea in the St. Lawrence River valley at about 11.6 ka BP. New seismo- and litho-stratigraphic information with ostracode data from the offshore lacustrine sediments were integrated with the traditional data of shorelines, uplift histories of outlets, and radio-carbon-dated shallow-water evidence of transgressions and regressions to reconstruct the water level history and paleolimnological record for the northern Huron basin for the 11-7 ka BP period. Negative excursions in the δ18O isotopic composition of ostracodes and bivalves in southern Lake Michigan, southwestern Lake Huron and eastern

  20. The Tendaguru formation of southeastern Tanzania, East Africa: An alternating Late Jurassic to Early Cretaceous palaeoenvironment of exceptional status

    NASA Astrophysics Data System (ADS)

    Sames, B.

    2009-04-01

    Dinosaur remains have inspired considerable scientific interest in the Tendaguru formation of southeastern Tanzania during the 20th century; however, this formation is exceptional in many other respects. The Late Jurassic to Early Cretaceous deposits of the Tendaguru formation in the southwestern Tethys are unique because they represent a marginal marine palaeoenvironment with nonmarine faunal and floral content. It is a threefold succession of marginal marine to terrestrial, carbonate-siliciclastic sediments with cyclic character, consisting of three transgressive-regressive cycles. Revisitation of the type locality (the Tendaguru, a hill approximately 60km northwest of the town of Lindi) by a German-Tanzanian expedition in summer 2000 (Heinrich et al., 2001) resulted in a new standard section (hitherto unpublished, the informal terminology is indicated by the use of lower case in Tendaguru formation), a refined environmental model (Aberhan et al., 2002) and many new insights towards its geology (with evidence of event-sedimentation, Bussert and Aberhan, 2004), biostratigraphy and a better understanding of the Tendaguru palaeo-ecosystems and the palaeoclimate. Within the scope of the designation of a new standard section at the type locality, calcareous microfossils (ostracods, charophytes) have been described to supplement the ongoing discussion about the age and palaeoecology of the Tendaguru formation (Sames, 2008). Although only a few unevenly distributed layers across the section produced calcareous microfossils, the results are very promising. A total of 40 ostracode and 2 charophyte taxa could be distinguished. The non-marine part of the ostracod fauna provides an important contribution to the documentation of Purbeck/Wealden-type nonmarine palaeoenvironments and its microfaunas and -floras previously unknown from East Africa. The marine faunal part belongs to a relatively endemic southern (Gondwana) fauna. Together with other fossil groups, the

  1. Climate inferences between paleontological, geochemical, and geophysical proxies in Late Pleistocene lacustrine sediments from Summer Lake, Oregon, western Great Basin

    NASA Astrophysics Data System (ADS)

    Heaton, Eric; Thompson, Greg; Negrini, Rob; Wigand, Peter

    2016-04-01

    Paleontological, geochemical, and geophysical data from western Great Basin pluvial Summer Lake, Oregon have established a high resolution paleoclimate record during the late Pleistocene Mono Lake Excursion (~34.75 ka), Dansgaard-Oeschger interstadials 6-8, and the end of Heinrich Even 4 (~38 ka). Proxies of grain-size, magnetic susceptibility, carbon/nitrogen ratio, ostracode analysis and palynology from a depocenter core show new results with improved age control regarding high amplitude, high frequency changes in lake level, lake temperature, and regional precipitation and temperature which correspond directly with colder/warmer and respectively drier/wetter climates as documented with Northern Atlantic Greenland ice core data. Results from geophysical and geochemical analysis, and the presence of ostracode Cytherissa lacustris consistently demonstrate the correspondence of low lake conditions and colder water temperatures during Dansgaard-Oeschger stadials and the Mono Lake Excursion. The opposite holds true during interstadials. Smaller grain size, increases in carbon/nitrogen ratio and consistent absence of C. lacustris suggest periods of increased discharge into the lake, increased lake level, and warmer water temperatures. Warmer/wetter climate conditions are confirmed during interstadials 7 and 8 from pollen analysis. Existence of Atriplex, Rosaceae, Chrysothamnus and Ambrosia, and pollen ratios of Juniperus/Dip Pinus and (Rosaceae+Atriplex+Poaceae+Chrysothamnus+Ambrosia)/(Pinus+Picea+T. mertensiana+Sarcobatus) suggest warmer/wetter semi-arid woodland conditions during interstadials 7 and 8. This contrasts with absences in these pollens and pollen ratios indicating colder/drier continental montane woodland conditions during stadials and the Mono Lake Excursion. Increases in Juniper/Dip Pinus ratio suggest a warmer/wetter climate during interstadial 6 however additional proxies do not demonstrate comparative warmer/wetter climate, deeper lake level or

  2. Meltwater events and the Mediterranean reconnection at the Saalian-Eemian transition in the Black Sea

    NASA Astrophysics Data System (ADS)

    Wegwerth, Antje; Dellwig, Olaf; Kaiser, Jérôme; Ménot, Guillemette; Bard, Edouard; Shumilovskikh, Lyudmila; Schnetger, Bernhard; Kleinhanns, Ilka C.; Wille, Martin; Arz, Helge W.

    2014-10-01

    The last glacial-interglacial transition or Termination I (T I) is well documented in the Black Sea, whereas little is known about climate and environmental dynamics during the penultimate Termination (T II). Here we present a multi-proxy study based on a sediment core from the SE Black Sea covering the penultimate glacial and almost the entire Eemian interglacial ((133.5±0.7)-(122.5±1.7) ka BP). Proxies comprise ice-rafted debris (IRD), O and Sr isotopes as well as Sr/Ca, Mg/Ca, and U/Ca ratios of benthic ostracods, organic and inorganic sediment geochemistry, as well as TEX86 and UK‧37 derived water temperatures. The ending penultimate glacial (MIS 6, 133.5 to 129.9±0.7 ka BP) is characterised by mean annual lake surface temperatures of about 9 °C as estimated from the TEX86 palaeothermometer. This period is impacted by two Black Sea melt water pulses (BSWP-II-1 and 2) as indicated by very low Sr/Caostracods but high sedimentary K/Al values. Anomalously high radiogenic 87Sr/86Srostracod values (max. 0.70945) during BSWP-II-2 suggest a potential Himalayan source communicated via the Caspian Sea. The T II warming started at 129.9±0.7 ka BP, witnessed by abrupt disappearance of IRD, increasing δ18Oostracod values, and a first TEX86 derived temperature rise of about 2.5 °C. A second, abrupt warming step to ca. 15.5 °C as the prelude of the Eemian warm period is documented at 128.3 ka BP. The Mediterranean-Black Sea reconnection most likely occurred at 128.1±0.7 ka BP as demonstrated by increasing Sr/Caostracods and U/Caostracods values. The disappearance of ostracods and TOC contents >2% document the onset of Eemian sapropel formation at 127.6 ka BP. During sapropel formation, TEX86 temperatures dropped and stabilised at around 9 °C, while UK‧37 temperatures remain on average 17 °C. This difference is possibly caused by a habitat shift of Thaumarchaeota communities from surface towards nutrient-rich deeper and colder waters located above the gradually

  3. Early Eocene biota (ostracoda, foraminifera) and paleoenvironment of the Blue Marls in the Corbieres Hills (Aude, France): building a framework for the identification of early Eocene hyperthermals in continental margin records.

    NASA Astrophysics Data System (ADS)

    Pirkenseer, C.; King, C.; Steurbaut, E.; Speijer, R.

    2009-04-01

    The Corbières Foreland Basin represents the southeastern-most extension of the Aquitanian Basin and is thus palaeo(bio)geographically related to the West-European Cenozoic Basin. During the Ypresian (‘Ilerdien') a succession of marine carbonates (e.g., Calcaires blancs à Alvéolines), marine marls (Blue Marls, Marnes à Térebratulides), brackish marls to sandstones and subsequent fluvio-lacustrine sediments (e.g., Montlaur Molasse) were deposited in the Corbières Hills (Aude, France) area in several depositional sequences. The present study focuses on the upper part of the open marine Blue Marls and the overlying brackish marls and sandstones spanning about 120m thickness close to the village Pradelles-en-Val. Over one hundred samples were collected in 1m intervals in order to document the early Eocene biogeographical and paleoenvironmental evolution of this open marine sequence, through a quantitative analysis of the ostracod assemblages. Furthermore, we aim at identifying anomalous environmental conditions that might be expected to be associated with the early Eocene hyperthermals known as Elmo- (ETM2) and X-event (ETM3). These events are subordinate to the best known hyperthermal, the Paleocene-Eocene thermal maximum, which has been recorded in deep-sea to non-marine depositional settings. ETM2 and ETM3, however, have until now only been demonstrated in deep-sea sequences, not in shelf deposits. In accordance with biostratigraphical data derived from other outcrops in the region, the sampled succession is attributed to the interval of calcareous nannofossil zones NP10-NP12. The occurrences of planktonic foraminifera of the Morozovella subbotinae-group are in agreement with this stratigraphic position (P6-7) for the lower part of the profile. Recorded fossil groups include generally abundant marine ostracoda, bryozoa, benthic and planktonic foraminifera, fragments of echinoderms including ophiuroidea, moulds of gastropods (often pyritised), large dinocysts

  4. A quarter-million years of paleoenvironmental change at Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Kaufman, D.S.; Bright, Jordon; Dean, W.E.; Rosenbaum, J.G.; Moser, K.; Anderson, R. Scott; Colman, Steven M.; Heil, C.W., Jr.; Jiménez-Moreno, Gonzalo; Reheis, M.C.; Simmons, K.R.

    2009-01-01

    A continuous, 120-m-long core (BL00-1) from Bear Lake, Utah and Idaho, contains evidence of hydrologic and environmental change over the last two glacial-interglacial cycles. The core was taken at 41.95??N, 111.31??W, near the depocenter of the 60-m-deep, spring-fed, alkaline lake, where carbonate-bearing sediment has accumulated continuously. Chronological control is poor but indicates an average sedimentation rate of 0.54 mm yr-1. Analyses have been completed at multi-centennial to millennial scales, including (in order of decreasing temporal resolution) sediment magnetic properties, oxygen and carbon isotopes on bulk-sediment carbonate, organic- and inorganiccarbon contents, palynology; mineralogy (X-ray diffraction), strontium isotopes on bulk carbonate, ostracode taxonomy, oxygen and carbon isotopes on ostracodes, and diatom assemblages. Massive silty clay and marl constitute most of the core, with variable carbonate content (average = 31 ?? 19%) and oxygen-isotopic values (??18O ranging from -18??? to -5??? in bulk carbonate). These variations, as well as fluctuations of biological indicators, reflect changes in the water and sediment discharged from the glaciated headwaters of the dominant tributary, Bear River, and the processes that influenced sediment delivery to the core site, including lake-level changes. Although its influence has varied, Bear River has remained a tributary to Bear Lake during most of the last quarter-million years. The lake disconnected from the river and, except for a few brief excursions, retracted into a topographically closed basin during global interglaciations (during parts of marine isotope stages 7, 5, and 1). These intervals contain up to 80% endogenic aragonite with high ??18O values (average = -5.8 ?? 1.7???), indicative of strongly evaporitic conditions. Interglacial intervals also are dominated by small, benthic/tychoplanktic fragilarioid species indicative of reduced habitat availability associated with low lake levels

  5. Climate-driven hydrologic transients in lake sediment records: calibration of groundwater conditions using 20th Century drought

    NASA Astrophysics Data System (ADS)

    Donovan, Joseph J.; Smith, Alison J.; Panek, Valerie A.; Engstrom, Daniel R.; Ito, Emi

    2002-02-01

    The effect of 20th-century drought on groundwater and lakes in a climatically sensitive area of the Northern Great Plains (Grant County, western Minnesota) was investigated by analysis of lake sediments and historical air photos, in conjunction with groundwater flow simulations. Drought caused an observed 4.0 to 5.1 m lake-head decline between 1923 and 1938; all but three either dried completely or declined to <1.7 m depth. From the deepest (Elk Lake), a 210Pb-dated sediment core was analyzed for ostracode species distribution and geochemistry of C. Rawsoni shells (δ 18O, δ 13C, Mg/Ca, Sr/Ca). Mg/Ca and δ 13C increased during drought at the same time that salinity-tolerant ostracodes thrived, suggesting increasing salinity. However, δ 18O decreased during drought, anti-correlative with Mg/Ca. A numerical model for transient response of groundwater flow to drought, modeled after that of 1923-38, was constrained by drought-end recessional strand lines observed on air photos of one lake, with strand line elevations inferred from bathymetry. Simulated lake-water-level declines in the first 15 drought years were consistent with strand line elevations. The rate of decline was exponential at drought onset, slowing as water in lakes and wetlands receded to below land surface and lake evaporation declined. A near-steady state was attained between 40 and 50 simulation years after onset of drought, with the water table from 1-5 m below the level of dry lakebeds and only the two deepest lakes still holding water. They were, however, greatly constricted in area and depth. Simulated evaporation fluxes were reduced by over 50% within 15 years, despite increased ET rates, due to lake area constriction and water table declines. Both relate to land surface morphology beneath and around lakes. Model results suggest that lake-bed elevations exert control on the rate and ultimate level to which groundwater is depressed by drought. The deepest lakes in any region will tend to become

  6. Unravelling the chronology and evolution of the Pleistocene-Holocene basin in the hanging-wall of the 2009 L'Aquila earthquake fault by multidisciplinary approach (paleomagnetism, palaeontology, geochemistry and radiometric dating) on a 150 m deep hole

    NASA Astrophysics Data System (ADS)

    Mochales, T.; Porreca, M.; Smedile, A.; Buratti, N.; Macri', P.; Di Chiara, A.; Sagnotti, L.; Speranza, F.; Amoroso, S.; Nicolosi, I.; D'ajello Caracciolo, F.; Carluccio, R.; Di Giulio, G.; Vassallo, M.; Villani, F.; Civico, R.

    2013-12-01

    The Mw=6.1 L'Aquila earthquake struck the central Apennines (Italy), on April 6th, 2009. INSAR data showed that the maximum subsidence of ca. 15 cm was located in the continental Aterno Basin, partly controlled by the Paganica extensional fault, yielding the L'Aquila earthquake. Preliminary geological and geophysical surveys have been performed in the depocenter of the Aterno Basin to figure out the underground configuration and determine the best location for a deep hole. The drilling was performed in May-June 2013, recovering 151 m of continental Holocene and Pleistocene sediments. The upper sandy-silty sequence (41 m), interbedded with gravels, is interpreted as fluvial-alluvial origin. The lower clayey-silty sequence, interpreted as lacustrine sediments, continues downward until the bottom (disrupted by 30 m of gravels). The continuous sediment record of the hole is being processed along three stages: i) Description consists of the elaboration of stratigraphical logs, color description and photographic record of the core. The second stage consists of sampling for the different analyses. ii) Continuous samples (U-Channel) were collected from the undisturbed centre of the core for paleomagnetic measurements. Additional samples were collected in the clayey-silty fraction (10 to 25 cm spacing) for calcimetry, geochemical, palynological and ostracoda fauna analysis. Finally, individual levels rich in organic matter and charcoal were sampled for radiometric datings. Iii) The measurements include magnetic susceptibility, paleomagnetic and rock magnetic properties, content of calcium carbonate and 16/18 oxygen ratio, crumble and classification of fossils for pollens and ostracods analyses. Paleomagnetic analyses will hopefully allow us to obtain experimental constraints for dating the Holocene-Pleistocene sediments of the Aterno Basin. The presence of Carbon-14 in organic materials can yield absolute dating. Palynology, oxygen ratio and calcium carbonate content will

  7. Paleoenvironmental evolution of the East Carpathian foredeep during the late Miocene-early Pliocene (Dacian Basin; Romania)

    NASA Astrophysics Data System (ADS)

    Stoica, M.; Lazăr, I.; Krijgsman, W.; Vasiliev, I.; Jipa, D.; Floroiu, A.

    2013-04-01

    The thick and continuous Mio-Pliocene sedimentary successions of the Focşani Depression in the Dacian Basin of Romania provide an excellent opportunity to study the paleoecological changes in the Eastern Paratethys during the time when the Mediterranean and Black Sea experienced major sea level fluctuations related to the closure and re-opening of the marine connection to the Atlantic Ocean during the Messinian Salinity Crisis. These successions form the basis of high-resolution magneto-biostratigraphic studies that allow a detailed correlation to the standard Geological Time Scale. Here, we analyze the paleoenvironmental evolution of the East Carpathian foredeep by integrating micro- and macropaleontological data and sedimentological analyses. The ostracod and mollusc fossil associations from the Râmnicu Sărat river section indicate that the late Maeotian depositional environment was characterized by shallow waters and littoral to fluvio-deltaic sediments. The Maeotian-Pontian boundary (6.04 Ma) is marked by a marine ingression, comprising benthic (agglutinated and calcareous) and planktonic (Streptochilus spp.) foraminifera and nanofossils. Following this marine ingression, the Lower Pontian (Odessian; 6.04-5.8 Ma) fauna shows an increased bathymetry of the basin. The presence of ostracod species with eye tubercles indicates depositional environments within the photic zone (< 100 m). The Middle Pontian (Portaferrian; 5.8-5.5 Ma) is marked by a widespread sea level lowering resulting in dominant fluvio-deltaic conditions. This ecostratigraphy demonstrates that the main Messinian sea-level draw down (at 5.6-5.5 Ma) occurred in mid-Portaferrian times. Paleoenvironmental indicators show that the water level in the Foçsani Depression dropped less than 100 m during Mediterranean desiccation. The Dacian Basin remained filled with water, suggesting a positive hydrological balance for the region. This is compatible with the presence of a shallow barrier at Dobrogea

  8. The Holocene history of Lop Nur and its palaeoclimate implications

    NASA Astrophysics Data System (ADS)

    Liu, Chenglin; Zhang, Jia-Fu; Jiao, Pengcheng; Mischke, Steffen

    2016-09-01

    The Holocene hydrological history of Lop Nur in northwestern China's Tarim Basin and its response to climate conditions are inferred from a relatively well-dated multi-proxy record including grain-size, pollen and spores, and soluble salt data. A dated pit section (YKD0301) with a depth of 570 cm in the center of the dry Lop Nur Basin was investigated. The sediments contain a total of twenty fining-upward cycles as a result of strong discharge from the catchment to the lake during relatively wet conditions. The fluvial sediments were probably widely dispersed by wind-driven waves and currents in the large and shallow basin of Lop Nur. Higher runoff and dilution of lake waters are also indicated by lower contents of soluble salt in the sediments and recorded ostracod shells of brackish and oligohaline to freshwater species. In contrast, sediment sections with smaller mean grain size and fewer flood layers are dominated by aeolian sediments which were accumulated during drier periods. Ostracod shells are mostly lacking from these sections, suggesting a higher salinity in the lake. Lop Nur experienced six stages during the last 9 ka. Relatively wet conditions existed between 9.0-8.9, 8.7-5.1 and 2.4-1.8 ka, with periods of increased aridity in between and after 1.8 ka. The lowest salinity was recorded between 8.7 and 5.1 ka which represents the wettest phase during the last 9 ka and probably the regional Holocene Optimum. Relatively wet climate conditions between 2.4 and 1.8 ka and dry conditions afterwards possibly first fostered and later on caused the devastation of the ancient Loulan Kingdom in the region. The uppermost sediments of the section represent a massive salt crust formed during the final desiccation of the lake in the last century. The effective moisture change pattern of the Lop Nur region is roughly consistent with synthesized Holocene moisture records for western China dominated by the westerlies.

  9. Holocene environmental changes in northern Lebanon as inferred from a multiproxy study on lacustrine-palustrine sediment

    NASA Astrophysics Data System (ADS)

    Vidal, L.; Hage-Hassan, J.; Gasse, F. A.; Demory, F.; van Campo, E.; Develle, A.; Elias, A.

    2013-12-01

    The reconstruction of the Levantine post-glacial environmental evolution is essential to understand the interactions between variability of regional water cycle, dynamics of the global climate, and cultural evolution. Here, we present an Holocene record from the karstic Yammouneh basin (34.06N-34.09N; 36.0E-36.03E, 1360 m a.s.l.), located on the eastern flank of Mount Lebanon (northern Levant). Two new sedimentary profiles (from 1 gully and 1 trench) complement former data from 2 trenches and 1 core collected in different points of the basin (Daeron et al., 2007; Develle et al., 2009, 2010). A total of 42 AMS 14C dating (partly carbonized wood) provide a solid chronology from the YD to present. Holocene sediments (1.5 to 3.6 m thick) consist of pale lacustrine chalk interrupted by an ash layer and remarkable centimetric beds of ocher to dark brown silty clays used, in addition to 14C ages, as stratigraphical markers. Lacustrine biogenic remains are diversified and abundant (ostracods, gastropods, charophytes, chlorophyceae, plant debris...) all reflecting a freswater, generally shallow waterbody. We analysed the sediment mineralogy, TOM contents, magnetic properties (magnetic susceptibility and its frequency dependence), pollen and calcite oxygen isotope composition derived from ostracod shells. Results reveal the following main features : 1- intervals dominated by authigenic calcite suggest that the major water supply was the karstic springs, which still deliver Ca-rich water and low surface runoff; 2- the lake oxygen isotope composition has been impacted by the source isotope composition throughout the Holocene and by increased inland rainfall during the early Holocene; 3- a decideous oak forest, implying much more soil water availability than today, was developed around the lake from ca. 11.5 to 9.5 kyr (the very bad pollen preservation after 8.3 kyr reflects oxidation or frequent oscillations of the water level); 4- four paleosols evidenced from lithofacies and

  10. Radiocarbon ages and age models for the past 30,000 years in Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Colman, Steven M.; Rosenbaum, J.G.; Kaufman, D.S.; Dean, W.E.; McGeehin, J.P.

    2009-01-01

    Radiocarbon analyses of pollen, ostracodes, and total organic carbon (TOC) provide a reliable chronology for the sediments deposited in Bear Lake over the past 30,000 years. The differences in apparent age between TOC, pollen, and carbonate fractions are consistent and in accord with the origins of these fractions. Comparisons among different fractions indicate that pollen sample ages are the most reliable, at least for the past 15,000 years. The post-glacial radiocarbon data also agree with ages independently estimated from aspartic acid racemization in ostracodes. Ages in the red, siliclastic unit, inferred to be of last glacial age, appear to be several thousand years too old, probably because of a high proportion of reworked, refractory organic carbon in the pollen samples. Age-depth models for five piston cores and the Bear Lake drill core (BL00-1) were constructed by using two methods: quadratic equations and smooth cubic-splinefits. The two types of age models differ only in detail for individual cores, and each approach has its own advantages. Specific lithological horizons were dated in several cores and correlated among them, producing robust average ages for these horizons. The age of the correlated horizons in the red, siliclastic unit can be estimated from the age model for BL00-1, which is controlled by ages above and below the red, siliclastic unit. These ages were then transferred to the correlative horizons in the shorter piston cores, providing control for the sections of the age models in those cores in the red, siliclastic unit. These age models are the backbone for reconstructions of past environmental conditions in Bear Lake. In general, sedimentation rates in Bear Lake have been quite uniform, mostly between 0.3 and 0.8 mm yr-1 in the Holocene, and close to 0.5 mm yr-1 for the longer sedimentary record in the drill core from the deepest part of the lake. Copyright ?? 2009 The Geological Society of America.

  11. High-resolution analysis of upper Miocene lake deposits: Evidence for the influence of Gleissberg-band solar forcing

    PubMed Central

    Kern, Andrea K.; Harzhauser, Mathias; Soliman, Ali; Piller, Werner E.; Mandic, Oleg

    2013-01-01

    A high-resolution multi-proxy analysis was conducted on a 1.5-m-long core of Tortonian age (~ 10.5 Ma; Late Miocene) from Austria (Europe). The lake sediments were studied with a 1-cm resolution to detect all small-scale variations based on palynomorphs (pollen and dinoflagellate cysts), ostracod abundance, geochemistry (carbon and sulfur) and geophysics (magnetic susceptibility and natural gamma radiation). Based on an already established age model for a longer interval of the same core, this sequence can be limited to approx. two millennia of Late Miocene time with a resolution of ~ 13.7 years per sample. The previous study documented the presence of solar forcing, which was verified within various proxies on this 1.5-m core by a combination of REDFIT spectra and Gaussian filters. Significant repetitive signals ranged in two discrete intervals corresponding roughly to 55–82 and 110–123 years, fitting well within the lower and upper Gleissberg cycle ranges. Based on these results, the environmental changes along the 2000-year Late Miocene sequence are discussed. No major ecological turnovers are expected in this very short interval. Nonetheless, even within this brief time span, dinoflagellates document rapid changes between oligotrophic and eutrophic conditions, which are frequently coupled with lake stratification and dysoxic bottom waters. These phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria. The pollen record indicates rather stable wetland vegetation with a forested hinterland. Shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms. These are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction. Such influence is most likely caused by solar cycles, leading to a change in source area for the input into the lake. Furthermore, these solar-induced variations seem to be modulated by longer solar cycles

  12. Ostracoda and Foraminifera associated with macrofauna of marginal marine origin in continental sabkha sediments of Tayma (NW Saudi Arabia)

    NASA Astrophysics Data System (ADS)

    Pint, Anna; Frenzel, Peter; Engel, Max; Plessen, Birgit; Melzer, Sandra; Brückner, Helmut

    2016-04-01

    The oasis Tayma in northwestern Saudi Arabia (27°38'N, 38°33'E) is well known for its rich archaeological heritage and also hosts a key sedimentary record of Holocene environmental change.The palaeontologically investigated material comes from two 5.5 m long sediment cores taken in the northeastern and central part of the sabkha and two outcrops of shoreline deposits at the northeastern and southwestern margin of a large lake. Microfossil-rich layers have an age of about 9.2-ca. 8 ka BP. The sandy and carbonate-dominated sediments contain autochthonous balanids, the gastropods Melanoides tuberculatus and hydrobiids as well as the foraminifers Ammonia tepida (Cushman, 1926), Quinqueloculina seminula (Linnaeus, 1758), and Flintionoides labiosa (&dacute;Orbigny, 1839). This brackish water association is completed by partially mass-occurrence of Cyprideis torosa (JONES, 1850), an euryhaline and generally widely tolerant ostracod species. Only the smooth shelled morphotype littoralis occurs. The association indicates a large brackish water lake with temporary freshwater inflows. All species documented originate in the marginal marine environment of the Red or Mediterranean Sea within the intertidal zone and hence they are adapted for strong environmental changes. We assume negative water balance under arid climatic conditions as cause for the high salinity of this athalassic lake. Sieve-pore analyses and shell chemistry suppose a trend of increasing salinity towards the top of the studied microfossil-bearing sections. This pattern is confirmed by increasing test malformation ratios of foraminifers. The marine origin of the fauna is surprising in this area 250 km away from the sea in an altitude of about 800 m a.s.l. We assume an avian-mediated transport of eggs, larvae or even adult animals to this site. The brackish water character of the lake enabled a permanent settling of marginal marine foraminifers, ostracods and even macrofauna as gastropods and balanids. The

  13. Holocene sea-level oscillations and environmental changes on the Eastern Black Sea shelf

    USGS Publications Warehouse

    Ivanova, E.V.; Murdmaa, I.O.; Chepalyga, A.L.; Cronin, T. M.; Pasechnik, I.V.; Levchenko, O.V.; Howe, S.S.; Manushkina, A.V.; Platonova, E.A.

    2007-01-01

    A multi-proxy study of four sediment cores from the Eastern (Caucasian) Black Sea shelf revealed five transgressive-regressive cycles overprinted on the general trend of glacioeustatic sea-level rise during the last 11,000??14C yr. These cycles are well represented in micro-and macrofossil assemblages, sedimentation rates, and grain size variations. The oldest recovered sediments were deposited in the Neoeuxinian semi-freshwater basin (??? 10,500-9000??14C yr BP) and contain a Caspian-type mollusk fauna dominated by Dreissena rostriformis. Low ??18O and ??13C values are measured on this species. The first appearance of marine mollusks and ostracodes from the Mediterranean is established in this part of the Black Sea at ??? 8200??14C yr BP, i.e., about 1000-2000??yr later than the appearance of marine microfossils in the deeper part of the sea. The Early Holocene (Bugazian to Vityazevian) condensed section of shell and shelly mud sediments with at least two hiatuses represent a high-energy shelf-edge facies. It contains a transitional assemblage representing a mixture of Caspian and Mediterranean fauna. This pattern suggests a dual-flow regime via the Bosphorus after 8200??14C yr BP. Caspian species disappear and oligohaline species decrease in abundance during the Vityazevian-Prekalamitian cycle. Later, during the Middle to Late Holocene, low sea-level stands are characterized by shell layers, whereas silty mud with various mollusk and ostracode assemblages rapidly accumulated during transgressions. Restricted mud accumulation, as well as benthic faunal composition and abundance, suggest high-energy and well-ventilated bottom water during low sea-level stands. A trend of 18O enrichment in mollusk shells points to an increase in bottom-water salinity during the Vityazevian to Kalamitian transgressions (??? 7000 to 5700??14C yr BP) due to a more open connection with the Mediterranean, while a pronounced increase in polyhaline species abundance is established during

  14. The palaeoecologic and biostratigraphic evaluation of Middle Miocene freshwater sediments and microfossils near Denkendorf (Bavaria)

    NASA Astrophysics Data System (ADS)

    Pirkenseer, C.; Reichenbacher, B.

    2009-04-01

    Isolated freshwater sediments that partially cover the Jurassic limestones of the Swabian and Franconian Alb represent the northernmost expansion of the Molasse sediments. These sediments represent the analogue to the Brackish Molasse and part of the Upper Freshwater Molasse (Ottnangian to Badenian). Samples of six drillcores from the vicinity of Denkendorf (Franconian Alb, Bavaria) yielded ostracods of the superfamily Cypridoidea, frequent oogonia of charophytes, otoliths of the family Gobiidae, teeth of several taxa of micromammals as well as abundant material of amphibians, reptiles and gastropods. The sediments show a general trend from basal, more clastic influenced deposits to uniformly developed marly sediments with freshwater carbonate intercalations. The acme of microfossil occurrences is associated with the latter section. The palaeoecologic analysis characterises the environment as structured littoral zone (e.g. Pseudocandona steinheimensis, Gyraulus sp., Planorbarius sp., Rana ridibunda, Triturus sp.) of a larger oligo- to mesotrophic (Chara spp., Nitellopsis spp.) low-energy freshwater system under a warm subtropical to tropical climate (Diplocynodon cf. D. styriacus, Channa sp.). The cooccurrence of suboxia- and oligotrophy-tolerant species like Palaeocarassius sp. and Channa sp. may indicate short intervals of regional depletion of oxygene and raise of nutrient content. Mediocypris candonaeformis and Gobius latiformis represent relict species of the preceding Brackwassermolasse. Terrestrial elements include Proboscidea (phalanx), Cervidae (astragalus), land turtles (Testudo sp.) and gastropods (Clausiliidae, Pupillidae, Cepaea sp.). The occurrence of Jurassic xenoclasts and bean iron ore indicate the presence of a tributary system. The faunal and floral assemblages show close affinities to other localities of the Molasse Basin (e.g., Sandelzhausen). In accordance with the depositional history this indicates a palaeogeographic connection with the

  15. Elevated biological productivity as a trigger for the Holocene sapropel in the Black Sea during its reconnection with the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Yanchilina, A.; Ryan, W. B.; Kenna, T. C.

    2013-12-01

    Sapropelic sedimentation characterizes the mid-Holocene section of the Black Sea strata, ranging from ~7500 to 3000 kyr BP. The level of organic carbon in the sapropel reaches 20% and the timing of the onset is independent of depth. However, it is unclear what sequence of events led to the development of the sapropel and how exactly its deposition was related to the connection of the Black Sea with the Mediterranean. One component that contributes to the uncertainty is a ~1000 kyr BP jump in age across the sapropel interface derived from radiocarbon dating of carbonate material. This study looks at records of XRF done on dry and wet sediments (i.e., Cu, Mo, Br) in addition to radiocarbon and stable isotope measurements on shells of ostracods. Cu, Mo, and Br all increase substantially from their low abundances in the glacial, post-glacial, and early Holocene gray clay almost concurrently. An increase in Cu indicates the rise of nutrients in the surface water and is coincident with a rise in Corg. Mo rises after Cu; it is attributed to the onset of anoxia, as it precipitates out of the water column in an environment lacking oxygen. Br increases last, attributed to the rise of the bottom dense salt water layer to the surface and its uptake by phytoplankton. Stable isotope results show that the δ18O rises from -1 to 0.3 ‰ and δ13C rises from -3 to -0.5 ‰ prior to the disappearance of ostracods in the sediment and indicates that anoxia started after the Black Sea-Lake connected with the Mediterranean. These results suggest that it was increased biological productivity that initially led to the deposition of the sapropel and only later to anoxia that then reinforced the highly organic content of the preserved sediment for thousands of years. The one thousand year jump in radiocarbon is interpreted as a decrease in the reservoir age of the water due to the replacement of stratified Black Sea that has accumulated old carbon and a large reservoir age with

  16. Palaeoceanography & Palaeoclimate during the penultimate Glacial-Interglacial transition in the Black Sea - Termination II

    NASA Astrophysics Data System (ADS)

    Wegwerth, Antje; Dellwig, Olaf; Kaiser, Jérôme; Bard, Edouard; Ménot, Guillemette; Nowaczyk, Norbert; Plessen, Birgit; Schnetger, Bernhard; Shumilovskikh, Lyudmila; Arz, Helge

    2013-04-01

    The epicontinental Black Sea is very sensitive to environmental changes thus forming an ideal archive of regional climate change and teleconnective responses to the coupled North Atlantic ocean-atmosphere system. Here we focus on the climatic and hydrological evolution of the SE Black Sea during the glacial-interglacial transition of Termination II to the Eemian (~134-122 ka BP) by using different geochemical and sedimentological proxies. Long-term cold conditions during the ending penultimate glacial are provided by TEX86 derived summer sea-surface temperatures (SST) of around 9°C and are thus considerable lower than present values of about 23°C. Coastal ice formation during extreme winters accounted for huge discharge of ice rafted debris (IRD) until 130.5 ka BP. Milder more humid conditions during this period are indicated for instance by elevated Cr/Al values typical for an ultramafic Pontic Mountain source (Piper and Calvert, 2011) thereby suggesting an increased sediment load mainly from the east-Anatolian rivers Kizilirmak and Yesilirmak. The abrupt disappearance of IRD along with increasing δ18O, Mg/Ca, and Sr/Ca of benthic ostracods (Candona spp.) resulted from slightly rising temperatures (SST 11°C) until 128.8 ka BP. Thereafter, SST rapidly increased within less than 500 years to about 25°C revealing a dramatic change from glacial to interglacial conditions. First analyses of U/Ca-ratios of ostracods show sharply increasing values not before ~128.3 ka BP, synchronous to the appearance of larval Mytilus galloprovincialis shells, due to the Mediterranean transgression into the Black Sea. The simultaneous increase of TOC and Mo/Al of the bulk sediment indicates the development of oxygen-deficient bottom waters and Eemian sapropel formation favoured by the establishment of a halocline shortly after the Mediterranean-Black Sea reconnection. About 500 years after the temperature maximum, the continental environment responded to the warming by elevated

  17. Is there a distinct continental slope fauna in the Antarctic?

    NASA Astrophysics Data System (ADS)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  18. The Palaeoclimate of Wadi Shati, Libyan Sahara: the last 130 ka

    NASA Astrophysics Data System (ADS)

    Drake, Nick A.; Lem, Rachel E.; Armitage, Simon J.; White, Kevin H.; El-Hawat, Ahmed; Salem, Mustafa J.; Hounslow, Mark; Franke, Jan

    2014-05-01

    The Fezzan region of Libya forms a large closed basin that contains a wealth of ancient palaeolake and riverine sediments indicative of past humidity in the central Sahara. We have used remote sensing, DEM analysis and Ultra Ground Penetrating Radar to map these features and have dated them using OSL and radiocarbon methods. Results suggest humid conditions during both MIS 5 and the Holocene with larger lakes and more extensive river systems being present during MIS 5 suggestive of greater humidity at this time. A 4m core was collected from Holocene sediments of the largest lake found in the region (1200 km2 during MIS5 and 660 km2 during the Holocene). Core sediments were dated using OSL and analysed using XRF, Ion Chromatography, Laser Granulometry and chemical extractions for ostracods, diatoms, pollen and phytoliths. The base of the core is dominated by clays deposited in a perennial lake environment from 7.75 ka to 6.6 ka. Gypsum deposition started at about 6.5 ka indicating a more arid environment. Four clay layers are found amongst the gypsum from 6.3 to 6.25 ka, 6.2 to 6.1, 6.0 to 5.8 and 5.7-5.6 ka suggests that aridification was not a sudden event, but consisted of a series of arid/humid oscillations before the lake finally desiccated just before 5 ka. No pollen, diatoms or ostracods are preserved in the sediments but phytoliths were present. Both tree and grass phytoliths were found in lower parts of the core, suggesting a wooded savannah environment from 7.75 to about 7 ka. Trees decline and grass increases up the core, signifying an increasingly arid environment. By the time the first gypsum bed is deposited at about 6.5 ka trees have disappeared and grass dominates. These results do not support the hypothesis of a sudden aridification of the Sahara at 4.9 ka and instead suggest that in the Fezzan region a gradual aridification had started by 7.75 ka and that the climate oscillated during the lake desiccation that started at 6.5 ka and was complete by

  19. Ostracoda and Foraminifera associated with macrofauna of marginal marine origin in continental sabkha sediments of Tayma (NW Saudi Arabia)

    NASA Astrophysics Data System (ADS)

    Pint, Anna; Frenzel, Peter; Engel, Max; Plessen, Birgit; Melzer, Sandra; Brückner, Helmut

    2016-04-01

    The oasis Tayma in northwestern Saudi Arabia (27°38'N, 38°33'E) is well known for its rich archaeological heritage and also hosts a key sedimentary record of Holocene environmental change.The palaeontologically investigated material comes from two 5.5 m long sediment cores taken in the northeastern and central part of the sabkha and two outcrops of shoreline deposits at the northeastern and southwestern margin of a large lake. Microfossil-rich layers have an age of about 9.2-ca. 8 ka BP. The sandy and carbonate-dominated sediments contain autochthonous balanids, the gastropods Melanoides tuberculatus and hydrobiids as well as the foraminifers Ammonia tepida (Cushman, 1926), Quinqueloculina seminula (Linnaeus, 1758), and Flintionoides labiosa (d'Orbigny, 1839). This brackish water association is completed by partially mass-occurrence of Cyprideis torosa (JONES, 1850), an euryhaline and generally widely tolerant ostracod species. Only the smooth shelled morphotype littoralis occurs. The association indicates a large brackish water lake with temporary freshwater inflows. All species documented originate in the marginal marine environment of the Red or Mediterranean Sea within the intertidal zone and hence they are adapted for strong environmental changes. We assume negative water balance under arid climatic conditions as cause for the high salinity of this athalassic lake. Sieve-pore analyses and shell chemistry suppose a trend of increasing salinity towards the top of the studied microfossil-bearing sections. This pattern is confirmed by increasing test malformation ratios of foraminifers. The marine origin of the fauna is surprising in this area 250 km away from the sea in an altitude of about 800 m a.s.l. We assume an avian-mediated transport of eggs, larvae or even adult animals to this site. The brackish water character of the lake enabled a permanent settling of marginal marine foraminifers, ostracods and even macrofauna as gastropods and balanids. The studied

  20. Seasonal Dynamics of Sublittoral Meiobenthos in Relation to Phytoplankton Sedimentation in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Ólafsson, E.; Elmgren, R.

    1997-08-01

    Meiobenthic metazoans (40-500) μm were sampled monthly at a 37 m deep station in the north-western Baltic Sea proper. Nematodes dominated the meiofauna, ranging from 67% of total abundance in February to 91% in September. Harpacticoid copepods were the second most common group, ranging from 2% in September to 15% in February. Total meiofauna shell-free dry weight biomass was lowest in winter (0·9 mg 10 cm -2in January), and increased rapidly following the spring bloom, to high values in May-July (peak 1·7 mg 10 cm -2in July). As an annual average, ostracods contributed most to biomass, 38%, while nematodes and harpacticoids made up 24 and 15%, respectively. Only nematodes were common below 2 cm depth in the sediment, and few nematodes penetrated below 4 cm. Of Wieser's morphologically based nematode feeding groups, epistrate feeders dominated the surface sediment, and non-selective deposit feeders dominated the deeper layer in May. Total nematode abundance was significantly different among dates, with lowest numbers in winter and spring (October-April), and almost doubled within about 2 months after the spring phytoplankton bloom in March. There was a significant increase in selective deposit feeders and epistrate feeders after the spring bloom. Harpacticoid copepods were almost all of two species, Pseudobradyasp. and Microarthridion littorale, both of which differed significantly in abundance among months, and displayed continuous reproduction throughout the year, with a peak in pairs in precopula in winter for Pseudobradyasp. and in ovigerous females in M. littoraleafter the spring bloom. Pseudobradyawas significantly more numerous in winter than in other seasons. Microarthridion littoralehad its highest abundance from July to October. Three species of ostracods were common throughout the year and all differed significantly in numbers among months. Turbellaria, Kinorhyncha were found in lowest numbers during winter and peaked in summer. The peak of newly

  1. Depositional environment, foraminifer content and ESR ages of Quaternary Gediz Delta Sediments (Eastern Aegean Sea, İzmir-Western Turkey)

    NASA Astrophysics Data System (ADS)

    Gökçe Benli, Ekin; Aydın, Hülya; İşintek, İsmail; Engin, Birol; Şengöçmen, Berna

    2016-04-01

    Sediments and fossil content of Gediz Delta (Eastern Aegean Sea - İzmir) were examined based on the drilling core samples of the YSK-C and SK-246 drilling. W-SW part of the Delta is represented by continental delta sediments up to 6 meters and shallow marine detritic sediments up to 35 meters in the YSK-C drilling. Continental part consists of an soiled, graveled, muddy and sandy sediment in terms of rich organic substance. As for marine part, it consists of bioclast, muddy, fine graveled sand and by repetition of pebble, sand and bioclast bearing mud layers. Bioclasts comprise of bivalvia, echinoid, ostracod, gastropod, foramifer and bryozoa fragments. Benthic foraminiferal fauna determinated in the marine levels are represented by 55 bethic, 2 planktonic species. These foraminifers and bioclasts reflect that the W-SW part of the delta, has been occured in marine conditions between 8-31m deep. E-NE part of the delta is generally represented by continental sediments up to 43.5m in SK-246 drilling. In addition, it includes marine levels in 18-19 m, 23-24 m and 36-37,5 m intervals. Continental sediments of E-NE part is generally represented by calcareous and sandy mud rocks which mostly includes ash, tuff, and pebble derived from Neogene volcanic rocks. As for marine levels, it is composed of calcareous mud stones and calcareous clay stones including very thin gastropod, bivalvia and ostracod in 18- 19 and 36-37.5 meters whereas it is represented by sandy mud stones including a great deal of bentic foraminifer, bivalvia, bryozoa, echinoid, gastropod in 23-24 metres. Thus show that E-NE part of the delta is usually in continental condition but it is occasionally covered by sea. In aging studies of YSK-C core done by ESR method, age of 8-9 m interval is determined to be 11. 376 ± 0,067 Ka; however ages of 10-11m and 24-25 m intervals are revealed to be 16.466 ± 0,016 Ka and 15.344 ± 0,021 Ka respectively; finally age of 25-26 m interval is found to be 19.995 ± 0

  2. Holocene environmental changes in northern Lebanon as inferred from a multiproxy study on lacustrine-palustrine sediment

    NASA Astrophysics Data System (ADS)

    Vidal, Laurence; Jenna, Hage-Hassen; Demory, François; Develle, Anne-Lise; van Campo, Elise; Elias, Ata

    2016-04-01

    The reconstruction of the Levantine post-glacial environmental evolution is essential to understand the interactions between variability of regional water cycle, dynamics of the global climate, and cultural evolution. We present a paleolacustrine record from the karstic Yammouneh basin (34.06N-34.09N; 36.0E-36.03E, 1360 m a.s.l.), located on the eastern flank of Mount Lebanon (northern Levant). Holocene sediments (retrieved from gully and a trenbch) (1.5 to 3.6 m thick) consist of pale lacustrine chalk interrupted by an ash layer and remarkable centimetric beds of ocher to dark brown silty clays used, in addition to 14C ages, as stratigraphical markers. Lacustrine biogenic remains are diversified and abundant (ostracods, gastropods, charophytes, chlorophyceae, plant debris…) all reflecting a freswater, generally shallow waterbody. We analysed the sediment mineralogy and geochemistry, TOM contents, magnetic properties, pollen and calcite oxygen isotope composition derived from ostracod shells. These sequences are compared to former data from 2 trenches and 1 core collected in different points of the basin (Daeron et al., 2007; Develle et al., 2009, 2010). A total of 42 AMS 14C dating (partly carbonized wood) provide a solid chronology from the YD to present. Results reveal the following main features : 1- intervals dominated by authigenic calcite suggest that the major water supply was the karstic springs, which still deliver Ca-rich water and low surface runoff; 2- the lake oxygen isotope composition has been impacted by the source isotope composition throughout the Holocene and by increased inland rainfall during the early Holocene; 3- a decideous oak forest, implying much more soil water availability than today, was developed around the lake from ca. 11.5 to 9.5 kyr (the very bad pollen preservation after 8.3 kyr reflects oxidation or frequent oscillations of the water level); 4- four paleosols evidenced from lithofacies and magnetic properties are identified

  3. Black Mats, Spring-Fed Streams, and Late-Glacial-Age Recharge in the Southern Great Basin

    USGS Publications Warehouse

    Quade, Jay; Forester, R.M.; Pratt, W.L.; Carter, C.

    1998-01-01

    Black mats are prominent features of the late Pleistocene and Holocene stratigraphic record in the southern Great Basin. Faunal, geochemical, and sedimentological evidence shows that the black mats formed in several microenvironments related to spring discharge, ranging from wet meadows to shallow ponds. Small land snails such as Gastrocopta tappaniana and Vertigo berryi are the most common mollusk taxa present. Semiaquatic and aquatic taxa are less abundant and include Catinellids, Fossaria parva, Gyraulus parvus, and others living today in and around perennial seeps and ponds. The ostracodes Cypridopsis okeechobi and Scottia tumida, typical of seeps and low-discharge springs today, as well as other taxa typical of springs and wetlands, are common in the black mats. Several new species that lived in the saturated subsurface also are present, but lacustrine ostracodes are absent. The ??13C values of organic matter in the black mats range from -12 to -26???, reflecting contributions of tissue from both C3 (sedges, most shrubs and trees) and C4 (saltbush, saltgrass) plants. Carbon-14 dates on the humate fraction of 55 black mats fall between 11,800 to 6300 and 2300 14C yr B.P. to modern. The total absence of mats in our sample between 6300 and 2300 14C yr B.P. likely reflects increased aridity associated with the mid-Holocene Altithermal. The oldest black mats date to 11,800-11,600 14C yr B.P., and the peak in the 14C black mat distribution falls at ???10,000 14C yr B.P. As the formation of black mats is spring related, their abundance reflects refilling of valley aquifers starting no later than 11,800 and peaking after 11,000 14C yrB.P. Reactivation of spring-fed channels shortly before 11,200 14C yr B.P. is also apparent in the stratigraphic records from the Las Vegas and Pahrump Valleys. This age distribution suggests that black mats and related spring-fed channels in part may have formed in response to Younger Dryas (YD)-age recharge in the region. However, the

  4. Oxygen-isotope variations in post-glacial Lake Ontario

    NASA Astrophysics Data System (ADS)

    Hladyniuk, Ryan; Longstaffe, Fred J.

    2016-02-01

    The role of glacial meltwater input to the Atlantic Ocean in triggering the Younger Dryas (YD) cooling event has been the subject of controversy in recent literature. Lake Ontario is ideally situated to test for possible meltwater passage from upstream glacial lakes and the Laurentide Ice Sheet (LIS) to the Atlantic Ocean via the lower Great Lakes. Here, we use the oxygen-isotope compositions of ostracode valves and clam shells from three Lake Ontario sediment cores to identify glacial meltwater contributions to ancient Lake Ontario since the retreat of the LIS (∼16,500 cal [13,300 14C] BP). Differences in mineralogy and sediment grain size are also used to identify changes in the hydrologic regime. The average lakewater δ18O of -17.5‰ (determined from ostracode compositions) indicates a significant contribution from glacial meltwater. Upon LIS retreat from the St. Lawrence lowlands, ancient Lake Ontario (glacial Lake Iroquois) lakewater δ18O increased to -12‰ largely because of the loss of low-18O glacial meltwater input. A subsequent decrease in lakewater δ18O (from -12 to -14‰), accompanied by a median sediment grain size increase to 9 μm, indicates that post-glacial Lake Ontario received a final pulse of meltwater (∼13,000-12,500 cal [11,100-10,500 14C] BP) before the onset of hydrologic closure. This meltwater pulse, which is also recorded in a previously reported brief freshening of the neighbouring Champlain Valley (Cronin et al., 2012), may have contributed to a weakening of thermohaline circulation in the Atlantic Ocean. After 12,900 cal [11,020 14C] BP, the meltwater presence in the Ontario basin continued to inhibit entry of Champlain seawater into early Lake Ontario. Opening of the North Bay outlet diverted upper Great Lakes water from the lower Great Lakes causing a period (12,300-8300 cal [10,400-7500 14C] BP) of hydrologic closure in Lake Ontario (Anderson and Lewis, 2012). This change is demarcated by a shift to higher δ18Olakewater

  5. Black Mats, Spring-Fed Streams, and Late-Glacial-Age Recharge in the Southern Great Basin

    NASA Astrophysics Data System (ADS)

    Quade, Jay; Forester, Richard M.; Pratt, William L.; Carter, Claire

    1998-03-01

    Black mats are prominent features of the late Pleistocene and Holocene stratigraphic record in the southern Great Basin. Faunal, geochemical, and sedimentological evidence shows that the black mats formed in several microenvironments related to spring discharge, ranging from wet meadows to shallow ponds. Small land snails such as Gastrocopta tappanianaand Vertigo berryiare the most common mollusk taxa present. Semiaquatic and aquatic taxa are less abundant and include Catinellids, Fossaria parva, Gyraulus parvus,and others living today in and around perennial seeps and ponds. The ostracodes Cypridopsis okeechobiand Scottia tumida,typical of seeps and low-discharge springs today, as well as other taxa typical of springs and wetlands, are common in the black mats. Several new species that lived in the saturated subsurface also are present, but lacustrine ostracodes are absent. The δ 13C values of organic matter in the black mats range from -12 to -26‰, reflecting contributions of tissue from both C 3(sedges, most shrubs and trees) and C 4(saltbush, saltgrass) plants. Carbon-14 dates on the humate fraction of 55 black mats fall between 11,800 to 6300 and 2300 14C yr B.P. to modern. The total absence of mats in our sample between 6300 and 2300 14C yr B.P. likely reflects increased aridity associated with the mid-Holocene Altithermal. The oldest black mats date to 11,800-11,600 14C yr B.P., and the peak in the 14C black mat distribution falls at ˜10,000 14C yr B.P. As the formation of black mats is spring related, their abundance reflects refilling of valley aquifers starting no later than 11,800 and peaking after 11,000 14C yr B.P. Reactivation of spring-fed channels shortly before 11,200 14C yr B.P. is also apparent in the stratigraphic records from the Las Vegas and Pahrump Valleys. This age distribution suggests that black mats and related spring-fed channels in part may have formed in response to Younger Dryas (YD)-age recharge in the region. However, the

  6. Reconstructing late Quaternary deep-water masses in the eastern Arctic Ocean using benthonic Ostracoda

    USGS Publications Warehouse

    Jones, R. Ll; Whatley, R.C.; Cronin, T. M.; Dowsett, H.J.

    1999-01-01

    The distribution of Ostracoda in three long cores from the deep eastern Arctic Ocean was studied to determine the palaeoceanographical history of the Eurasian Basin during the late Quaternary. The samples for this study were obtained from the Lomonosov Ridge, Morris Jesup Rise and Yermak Plateau during the Arctic 91 expedition. Ostracoda previously studied in coretops at the same sites as the present study have shown that individual species have a strong association with different water masses and bathymetry. Throughout the late Quaternary, cores exhibit ostracod-rich layers separated by barren intervals. On the basis of biostratigraphical, isotopic and palaeomagnetic data the fossiliferous levels are interpreted as representing interglacial stages. The twenty most significant species were selected for subsequent quantitative investigation using Cluster and Factor analyses, in order to determine similarity and variance between the assemblages. An additional statistical method employing Modern Analogues and the Squared Chord Distance dissimilarity coefficient was utilized to compare the present late Quaternary fossil samples with a modern Arctic database. The results reveal a major faunal division within the Arctic Ocean Deep Water (AODW). Highly abundant and diverse assemblages within the cores were found to group and have good analogues with the Recent bathyal depth (1000-2500 m) upper AODW assemblages. Conversely, assemblages with low abundance and diversity correlate well with abyssal depth (> 3000 m) lower AODW assemblages. The palaeoceanographical history is complicated by the influence of adjacent water masses such as Canada Basin Deep Water (CBDW), Greenland Sea Deep Water (GSDW) and most importantly, Arctic Intermediate Water (AIW), which all had an influence on the ostracod assemblages during the late Quaternary. An enhanced flow of warm saline AIW into the Eurasian Basin results in species-rich upper AODW assemblages having good analogues down to 2750 m

  7. A multi-proxy approach to identifying short-lived marine incursions in the Early Carboniferous

    NASA Astrophysics Data System (ADS)

    Bennett, Carys; Davies, Sarah; Leng, Melanie; Snelling, Andrea; Millward, David; Kearsey, Timothy; Marshall, John; Reves, Emma

    2015-04-01

    This study is a contribution to the TW:eed Project (Tetrapod World: early evolution and diversification), which examines the rebuilding of Carboniferous ecosystems following a mass extinction at the end of the Devonian. The project focuses on the Tournaisian Ballagan Formation of Scotland and the Borders, which contains rare fish and tetrapod material. The Ballagan Formation is characterised by sandstones, dolomitic cementstones, paleosols, siltstones and gypsum deposits. The depositional environment ranges from fluvial, alluvial-plain to marginal-marine environments, with fluvial, floodplain and lacustrine deposition dominant. A multi-proxy approach combining sedimentology, palaeontology, micropalaeontology, palynology and geochemistry is used to identify short-lived marine transgressions onto the floodplain environment. Rare marginal marine fossils are: Chondrites-Phycosiphon, Spirorbis, Serpula, certain ostracod species, rare orthocones, brachiopods and putative marine sharks. More common non-marine fauna include Leiocopida and Podocopida ostracods, Mytilida and Myalinida bivalves, plants, eurypterids, gastropods and fish. Thin carbonate-bearing dolomitic cementstones and siltstone contain are the sedimentary deposits of marine incursions and occur throughout the formation. Over 600 bulk carbon isotope samples were taken from the 500 metre thick Norham Core (located near Berwick-Upon-Tweed), encompassing a time interval of around 13 million years. The results range from -26o to -19 δ13Corg, with an average of -19o much lighter than the average value for Early Carboniferous marine bulk organic matter (δ13C of -28 to -30). The isotope results correspond to broad-scale changes in the depositional setting, with more positive δ13C in pedogenic sediments and more negative δ13C in un-altered grey siltstones. They may also relate to cryptic (short-lived) marine incursions. A comparison of δ13C values from specific plant/wood fragments, palynology and bulk

  8. A census of marine zooplankton in the tropical/subtropical Atlantic from the surface to 5000 m.

    NASA Astrophysics Data System (ADS)

    Wiebe, P. H.; Bucklin, A.; Madin, L.; Angel, M. V.; Sutton, T.; Pages, F.; Hopcroft, R. R.

    2006-12-01

    Zooplankton from tropical/subtropical waters in the Atlantic Ocean were sampled from the surface to 5000 m, with a particular focus on the mesopelagic, bathypelagic, abyssopelagic zones. Sampling, on a cruise sponsored by the NOAA Ocean Exploration Program and the Census of Marine Life, was conducted at five stations from the northern Sargasso Sea to the equatorial waters northeast of Brazil. Environmental data and zooplankton samples were collected using three Multiple Opening/Closing Nets and Environmental Sensing Systems (MOCNESS): a 10-m opening/closing trawl with 335-um mesh nets sampled from 5000 to 1000 m and two smaller MOCNESS with similar or smaller mesh sampled the upper 1000 m. Ring net and water bottle casts, and blue-water SCUBA diving were also carried out. Samples were analyzed at sea using traditional morphological taxonomic approaches by a team of experts, followed by molecular systematic analysis, including determination of a DNA barcode (i.e., short DNA sequence for species recognition) for each species. Over 500 species were identified onboard ship; more than 1000 specimens were placed in a queue for barcoding; 87 species were barcoded at sea. For several taxonomic groups, a significant fraction of the region's species were collected and identified. Sixty-five species of planktonic ostracods were identified at sea out of the 140 known for the North Atlantic Ocean, with at least six undescribed species collected and the first DNA barcode for a planktonic ostracod obtained. At-sea analysis of samples also yielded identified specimens for more than 40 species of molluscs (pteropods, heteropods, etc.), more than 100 species of jellyfish, several hundred species of copepods, and more than 100 species of fish. In all, taxonomists estimated that at least 12 - 15 new species will be described from this effort. The special deployment of trawls to sample large volumes at great depths for small zooplankton yielded preliminary confirmation that species

  9. Constraints on the events surrounding the drainage of glacial Lake Ojibway based on James Bay Lowlands sedimentary sequences

    NASA Astrophysics Data System (ADS)

    Roy, M.; Dell'Oste, F.; Parent, M.; Veillette, J.

    2009-12-01

    Deglaciation of the James Bay region was closely related to the development of glacial Lake Ojibway. The northward retreat of the margin of the Laurentide sheet in this region was punctuated by at least three late-glacial (Cochrane) readvances into the Lake Ojibway basin, which occurred around late deglaciation time, shortly before the abrupt and final drainage of Lake Ojibway and concomitant incursion of the post-glacial Tyrrell Sea ~8 ka. Although paleogeographic reconstructions have traditionally portrayed the drainage of the lake occurring through the collapse of the residual ice mass, recent glaciological modeling suggests an alternative mechanism centered on subglacial flood(s). These glaciological considerations suggest that more than one drainage event may have occurred, possibly through different drainage pathways. Here we focus on the events that surround the drainage of Lake Ojibway by documenting late-glacial and Holocene stratigraphic sequences exposed along the Harricana, Nottaway, Broadback, and Rupert rivers in the James Bay lowlands, a region that lies near the final resting position of the ice margin during deglaciation. Our investigations indicate that the deglacial sequence consists of a carbonate-bearing readvance till, extensive Ojibway varves, and thick marine sediments. The contact between the glaciolacustrine and glaciomarine sediments is marked by a 50 cm-thick horizon composed of thinly laminated reddish and grey silt beds containing abundant rounded clay balls and disseminated clasts. This horizon is interpreted to reflect the abrupt drainage of Lake Ojibway. Radiocarbon dating of mollusks and foraminifers extracted from the uppermost part of the drainage horizon yielded ages of 7.64 and 8.02 14C ka BP. Micropaleontological examinations of the upper varve sequence revealed the presence of freshwater ostracods (Candona sp.), along with foraminifers. Stable isotopes (δ18O and δ13C) analyses on ostracods and foraminifers originating from

  10. Climatic variability and human impact during the last 2000 years in western Mesoamerica: evidence of late Classic (AD 600-900) and Little Ice Age drought events

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ramírez, A.; Caballero, M.; Roy, P.; Ortega, B.; Vázquez-Castro, G.; Lozano-García, S.

    2015-09-01

    We present results of analysis of biological (diatoms and ostracodes) and non-biological (Ti, Ca / Ti, total inorganic carbon, magnetic susceptibility) variables from an 8.8 m long, high-resolution (~ 20 yr sample-1) laminated sediment sequence from Lake Santa María del Oro (SMO), western Mexico. This lake lies at a sensitive location between the dry climates of northern Mexico, under the influence of the North Pacific subtropical high-pressure cell and the moister climates of central Mexico, under the influence of the seasonal migration of the intertropical convergence zone and the North American monsoon (NAM). The sequence covers the last 2000 years and provides evidence of two periods of human impact in the catchment, shown by increases in the diatom Achnanthidium minutissimum. The first from AD 100 to 400 (Early Classic) is related to the shaft and chamber tombs cultural tradition in western Mexico, and the second is related to Post-Classic occupation from AD 1100 to 1300. Both periods correspond to relatively wet conditions. Three dry intervals are identified from increased carbonate and the presence of ostracodes and aerophilous Eolimna minima. The first, from AD 500 to 1000 (most intense during the late Classic, from AD 600 to 800), correlates with the end of the shaft and chamber tradition in western Mexico after ca. AD 600. This late Classic dry period is the most important climatic signal in the Mesoamerican region during the last 2000 years, and has been recorded at several sites from Yucatan to the Pacific coast. In the Yucatan area, this dry interval has been related with the demise of the Maya culture at the end of the Classic (AD 850 to 950). The last two dry events (AD 1400 to 1550 and 1690 to 1770) correspond with the onset of, and the late, Little Ice Age, and follow largely the Spörer and Maunder minima in solar radiation. The first of these intervals (AD 1400 to 1550) shows the most intense signal over western Mexico; however this pattern is

  11. Siphateles (Gila) sp. and Catostomus sp. from the Pleistocene OIS-6 Lake Gale, Panamint Valley, Owens River system, California

    NASA Astrophysics Data System (ADS)

    Jayko, A. S.; Forester, R. M.; Smith, G. R.

    2014-12-01

    Panamint Valley lies within the Owens River system which linked southeastern Sierra Nevada basins between Mono Lake and Death Valley during glacial-pluvial times. Previous work indicates that late Pleistocene glacial-pluvial Lake Gale, Panamint Valley was an open system during OIS-6, a closed ground water supported shallow lake during OIS-4, and the terminal lake basin for the Owens River system during OIS-2. We here report the first occurrence of fossil fish from the Plio-Pleistocene Panamint basin. Fish remains are present in late Pleistocene OIS-6 nearshore deposits associated with a highstand that was spillway limited at Wingate Wash. The deposits contain small minnow-sized remains from both Siphateles or Gila sp. (chubs) and Catostomus sp. (suckers) from at least four locations widely dispersed in the basin. Siphateles or Gila sp. and Catostomus are indigenous to the Pleistocene and modern Owens River system, in particular to the historic Owens Lake area. Cyprinodon (pupfish) and Rhinichthys (dace) are known from the modern Amargosa River and from Plio-Pleistocene deposits in Death Valley to the east. The late Pleistocene OIS-6 to OIS-2 lacustrine and paleohydrologic record in Panamint basin is interpreted from ostracod assemblages, relative abundance of Artemia sp. pellets, shallow water indicators including tufa fragments, ruppia sp. fragments and the relative abundance of charophyte gyrogonites obtained from archived core, as well as faunal assemblages from paleoshoreline and nearshore deposits. The OIS-4 groundwater supported shallow saline lake had sufficiently low ratios of alkalinity to calcium (alk/Ca) to support the occurrence of exotic Elphidium sp. (?) foraminfera which are not observed in either OIS-2 or OIS-6 lacustrine deposits. The arrival of Owens River surface water into Panamint Basin during OIS-2 is recorded by the first appearance of the ostracod Limnocythere sappaensis at ~27 m depth in an ~100 m archived core (Smith and Pratt, 1957) which

  12. Climate History of the Southern San Joaquin Valley of California, USA: Authentic Paleoclimate Research with K-12 Teachers

    NASA Astrophysics Data System (ADS)

    Baron, D.; Negrini, R. M.; Palacios-Fest, M. R.; Auffant, K.

    2006-12-01

    For three summers, the Department of Geology at California State University, Bakersfield (CSUB) has invited teachers from local schools to participate in a research program that is investigating the climate history of the San Joaquin Valley of California. In each 4-week summer project, three elementary/middle school teachers and three high school teachers worked with CSUB faculty, undergraduate geology students, and a small group of high school students. The research centers around the analysis of 50-foot (15 m) sediment cores from two locations in the Tulare Lake basin. These cores preserve a regional climate record dating back to about 35,000 years before the present. Research tasks include the description of sediments from the cores for parameters such as grain size, color, and mineralogy. Sediment analyses include total organic and total inorganic carbon, as well as magnetic susceptibility. Ostracode shells were separated from the sediments, ostracode species present were identified and their abundances determined. Each teacher was put in charge of the description and analysis of several 5-foot (1.5 m) core segments. Each teacher was the leader of a research group including a CSUB geology student and one or two high school students. The groups were responsible for all aspects of the description and analysis of their core segments. They were also in charge of the paleoclimate interpretations and the presentation of their research results at the end of the summer projects. Surveys conducted before and after the summer program indicate that teacher's knowledge of climate change and regional geology, as well as their confidence in teaching Earth science at their schools increased. Follow- up surveys conducted a year after the first summer program indicate that the research experience had a lasting positive impact on teacher's confidence and their enthusiasm for teaching Earth science. Several of the teachers have developed lesson plans and/or field trips for their

  13. Increased Precipitation over the Yucatan Peninsula Inferred from the Spatial and Temporal Distribution of Late Holocene Foram Assemblages

    NASA Astrophysics Data System (ADS)

    Rachmallu, M.; Broach, K.; Paytan, A.; Street, J. H.

    2014-12-01

    As global climate warms, IPCC predictions suggest dry and seasonally dry regions will become dryer, increasing stress on water resources by growing urban populations (e.g. Southern California; Yucatan, Mexico). This study aims to reconstruct paleohydrologic trends during the late Holocene using foraminifera assemblages in Yucatan, Mexico to determine drought susceptibility in a region affected by migration of the Intertropical Convergence Zone (ITCZ). The ITCZ affects precipitation over the Yucatan Peninsula, potentially decreasing groundwater infiltration and thus reducing discharge in submarine springs at the peninsula margins. The field site Celestun Lagoon near Merida, Yucatan, Mexico, is dominated by spring and groundwater inputs at the northern terminus and opens to the Gulf of Mexico at the southern end resulting in a strong salinity gradient dependent on freshwater influx. We analyzed the foram assemblage in the top 6 cm of a set of 7 cores collected along a lagoonal transect (from the mouth to the head) and plotted the relative abundances of Ammonia beccarii, Elphidium sp., Quinqueloculina sp., and the ostracod Hemicyprideis cf. nichuptensis against site location. A. beccarii abundance increases from 40% near the head to 70% near the middle of the lagoon before dropping to <10% toward the saline lagoon mouth (high abundance in brackish salinity). Quinqueloculina sp. increases from 0% at the upper lagoon to nearly 40% near the mouth showing an opposite trend along the same transect. Elphidium sp. showed no clear trend (abundance range 10-28% throughout), and lowest H. nichuptensis abundance occurred at the middle of the lagoon (10%) increasing to the north and south (up to 60%). The inversely correlated spatial distribution between A. beccarii and Quinqueloculina sp. occurs vertically in an upper lagoon long core from 125-96 cm below sediment-water interface (14C age dates 3968-2820 ka), implying a decreasing salinity over ~1000 yrs and increased

  14. Comparison of physico-chemical parameters and zooplankton diversity in two perennial ponds at Aligarh, India.

    PubMed

    Parveen, Saltanat; Abdel Mola, Hesham R

    2013-07-01

    Investigations were carried out on the diversity of zooplankton in relation to physico-chemical parameters of two perennial ponds (Chautal Pond and Medical Pond) of Aligarh, India. Thirty nine species of holoplankton were identified belonging to copepoda (2 species), rotifera (28 species), cladocera (6 species) and protozoa (3 species). Other forms; like as meroplankton (insects) and tychoplankton (nematodes and ostracodes) were also recorded. Higher values of physico-chemical parameters and low zooplankton diversity were recorded in the Chautal Pond, whereas low values of physico-chemical parameters and high diversity were recorded in the Medical Pond. Ostracods considered to be the most dominant group in Medical Pond (32.16% of the total zooplankton) while Cladocerans are considered to be the most dominant group in Chautal Pond (38.83% of the total zooplankton). Rotifera contributed more in Medical Pond (16.42%) as compared to Chautal Pond (15.81%). Five species of Brachionus was recorded during study. Out of five, four Brachionus species were recorded in Chautal Pond while only two species were recorded in Medical pond. This indicates that Chautal Pond is more eutrophic than Medical pond. In addition, higher carbon dioxide values (37-105 mg l(-1)), low dissolved oxygen (0.7-3.3 mg I(-1)) and higher electrical conductivity values (1069-1691 mg l(-1)) were also indicative of eutrophic nature of Chautal Pond. Present study also revealed that total zooplankton species, species richness and diversity indices (Evenness, Shannon-Winner and Simpson) were comparatively higher in Medical pond. The rotifer species Philodina roseola (146 Org. l(-1)) and Monstyla closterocerca (109 Org. l(-1)) was dominated in Medical Pond while the rotifers Brachionus urceolaris (512 Org. l(-1)) and the cladocern species Ceriodaphnia cornuta (1540 Org. l(-1)) dominated in Chautal Pond during post-monsoon season. This might be due to the effect of rain water which played an important role in

  15. Lake Qinghai sediment geochemistry linked to hydroclimate variability since the last glacial

    NASA Astrophysics Data System (ADS)

    Jin, Zhangdong; An, Zhisheng; Yu, Jimin; Li, Fuchun; Zhang, Fei

    2015-08-01

    Geochemistry of basin sediments from semi-arid regions is valuable to understand past hydroclimatic changes. Here, we investigate the links of sedimentary geochemistry (Rb, Sr, Ca/Zr, TOC, and %CaCO3), carbonate mineralogy and ostracod shell δ18O of Lake Qinghai, a basin proximal to major dust production centers at mid-latitudes of the Northern Hemisphere, to changes in depositional conditions and hydroclimate during the past 32 ka. Surface lacustrine sediments are characterized by low-Rb, high-Sr, low-Rb/Sr, high-%CaCO3 and high-Ca/Zr values, in contrast to the chemical compositions of eolian loess (high-Rb, low-Sr, high-Rb/Sr, low-%CaCO3, and low-Ca/Zr). A direct comparison of soluble Ca and Sr in two short cores with instrumental water discharge data suggests that lacustrine precipitates in Lake Qinghai are dominated by authigenic aragonite formed under Ca2+-limited water conditions, and that the accumulation rate of aragonite dominantly depends on solute fluxes into the lake during the rainy seasons (late May to September). Our high-resolution down-core records show that sediments during the last glacial (∼32-19.8 ka) had high-Rb, low-Sr, low-%CaCO3, and low-Ca/Zr, indicating eolian dust (loess) accumulation in a desiccated basin under dry glacial conditions, further supported by grain size and pollen results. This type of sedimentation was maintained during the last deglacial (∼19.8-11.5 ka), but interrupted by episodic lacustrine precipitates with high-Sr, high-%CaCO3, high-Ca/Zr, and low-Rb. At ∼11.5 ka, sedimentary Rb/Sr, Ca/Zr, %CaCO3 and TOC show dramatic and permanent changes, implying an abrupt shift in the atmospheric circulation at the onset of the Holocene in the Lake Qinghai region. Lacustrine precipitates have persisted throughout the Holocene with a maximum during the early to mid-Holocene (∼10.5-8.0 ka). Since ∼8.0 ka, the gradual and significant decreases in aragonite and Sr accumulations in tandem with increasing dust deposit

  16. Moldavites from the Cheb Basin, Czech Republic

    NASA Astrophysics Data System (ADS)

    Bouska, V. J.; Mottl, V.; Rost, R.; Sevcik, J.

    1995-09-01

    Thirteen moladvites have been found on the surf side of the gravel beaches on the shore of the Jesenice water reservoir on the Odrava River. This spur lies about 1 250 m NW of the village Okrouhl at Cheb in Western Bohemia, Czech Republic, where only slightly rounded Pliocene gravels of the Vildgtejn Formation outcrop on the surface and form the bottom of the reservoir at this point. These gravels are also uncovered at the Tekaz Cheb gravel pit, 2 350 m to the NW from the find site. The bottom of the gravel pit and the basement of the moldavite-bearing gravel sands consist of the Miocene Cypris claystones. Red-brown andalusite and feldspar grains are typical minerals of the sandy gravels. The moldavites are lat in shape with deep sculpture, formed in a weakly acidic environment. Moldavites did not undergo prolonged transportation from the site of fall. Two samples have sharp grooves. The moldavites from the Cheb Basin are somewhat smoother to the touch and not as sharp as the moldavites from the Ceske Budejovice-Trebon area in Southern Bohemia. In a microscope, very fine secondary sculpture can be seen, probably formed in the water of the reservoir. The glass-matter is pure inside the samples and thus this is apparently repeated emphasizing of the original sculpture. The biggest specimens are No. 1 (5.44 g; 3 x 1.6 x 0.7 cm) and No. 8 (4.855 g; 3.2 x 1.7 x 0.5 cm). Their color ranges from bottle green to light bottle green to olive green or olive brown in two samples. In the shape, color, high content of bubbles and lechatelierite grains, density (rho = 2.34 - 2.38), refractive index (n = 1.4888 - 1.4936), and chemical composition of sample No. 5 (microprobe analysis: SiO2 - 78.70 wt. %, TiO2 - 0.35, Al2O3 - 10.13, FeO - 1.62, MnO - 0.12, MgO - 2.03, CaO - 3.11, Na2O - 0.42, K2O - 2.61) the moldavites of the Cheb Basin correspond to moldavites from the Ceske Budejovice-Trebon area in Southern Bohemia (1,2). The finds of moldavites in the Cheb Basin reflect the

  17. Relationship of Ordovician and Silurian reservoir development to unconformities at Midland farms and Inez fields, Andrews County, Texas

    SciTech Connect

    Mear, C.E.; Becher, J.W.

    1986-03-01

    Hydrocarbons are being produced at Midland Farms and Inez fields from Ellenburger dolomites and Fusselman limestones. Reservoirs developed there during Ordovician and Silurian periods of minor folding and faulting, followed by regional uplift and subaerial exposure of the carbonates. Vuggy, cavernous, and solution-enlarged fracture porosity was developed in the Lower Ordovician Ellenburger dolomites prior to deposition of the overlying Middle Ordovician shales of the Simpson Group. Vuggy and cavernous porosity developed in the Lower Silurian Fusselman crinoid-ostracod-pellet packstones and grainstones before deposition of the overlying Silurian Wristen shales. Montoya siliceous limestones of Late Ordovician age were truncated during a period of pre-Silurian erosion, but porosity development is not indicated in Montoya rock cuttings. Only minor amounts of porosity developed in the Lower to Middle Devonian Thirty-one packstones and wackestones as a result of uplift and erosion in the Middle Devonian. Regional compression during the post-Mississippian enhanced doubly plunging anticlines now having up to 91 m (300 ft) of closure at the Ellenburger through Thirty-one formations at Midland Farms and Inez fields. Fractures may have developed in Paleozoic limestones during this period of folding, but reservoir enhancement appears to have resulted only in the Ellenburger dolomites. Representative porosity measurements of the Ellenburger and Fusselman pay zones cannot be made from wireline log calculations, due to the fractured, vuggy, and cavernous nature of the porosity.

  18. Eustatic control on epicontinental basins: The example of the Stuttgart Formation in the Central European Basin (Middle Keuper, Late Triassic)

    NASA Astrophysics Data System (ADS)

    Franz, M.; Nowak, K.; Berner, U.; Heunisch, C.; Bandel, K.; Röhling, H.-G.; Wolfgramm, M.

    2014-11-01

    The deposition of the Stuttgart Formation ('Schilfsandstein'), commonly considered as a type-example of the Carnian Pluvial Event, was controlled by high frequent 4th order sequences that resulted in pre-, intra- and post-Schilfsandstein transgressions from Tethyan waters into the epicontinental Central European Basin (CEB). The pre-Schilfsandstein transgression flooded the CEB trough gates to the Southeast and resulted in a wide-spread inland sea that was characterised by increased biological productivity, predominantly oxic conditions and enabled the immigration of euryhaline marine fauna with plankton, ostracodes, fishes, bivalves and the gastropods Omphaloptychia suebica n. sp. and Settsassia stuttgartica n. sp. The rather short-term intra- and post-Schilfsandstein transgressions flooded the CEB from the Southwest and Southeast and established a shallow brackish inland sea that stretched up to North Germany. Both, the 4th and 3rd order sequences derived from the succession in the CEB correlate well with those derived from successions of Tethyan shelfs. Therefore pronounced circum-Tethyan eustatic cycles are evidenced and may have had considerable impact on prominent middle Carnian events: Reingraben turnover, Carnian Pluvial Event, Carnian Crisis and Mid Carnian Wet Intermezzo. The broad circum-Tethyan evidence of 106-year scale cycles suggests glacioeustatic sea-level changes even in the Triassic Greenhouse period.

  19. THE ANALYSIS OF BIOLUMINESCENCES OF SHORT DURATION, RECORDED WITH PHOTOELECTRIC CELL AND STRING GALVANOMETER.

    PubMed

    Harvey, E N; Snell, P A

    1931-03-20

    1. The rapid decay of luminescence in extracts of the ostracod crustacean Cypridina hilgendorfii, has been studied by means of a photoelectric-amplifier-string galvanometer recording system. 2. For rapid flashes of luminescence, the decay is logarithmic if ratio of luciferin to luciferase is small; logarithmic plus an initial flash, if ratio of luciferin to luciferase is greater than five. The logarithmic plot of luminescence intensity against time is concave to time axis if ratio of luciferin to luciferase is very large. 3. The velocity constant of rapid flashes of luminescence is approximately proportional to enzyme concentration, is independent of luciferin concentration, and varies approximately inversely as the square root of the total luciferin (luciferin + oxyluciferin) concentration. For large total luciferin concentrations, the velocity constant is almost independent of the total luciferin. 4. The variation of velocity constant with total luciferin concentration (luciferin + oxyluciferin) and its independence of luciferin concentration is explained by assuming that light intensity is a measure of the luciferin molecules which become activated to oxidize (accompanied with luminescence) by adsorption on luciferase. The adsorption equilibrium is the same for luciferin and oxyluciferin and determines the velocity constant. PMID:19872603

  20. Population fluctuation and vertical distribution of meiofauna in the Red Sea interstitial environment.

    PubMed

    El-Serehy, Hamed A; Al-Misned, Fahad A; Al-Rasheid, Khaled A

    2015-07-01

    The composition and distribution of the benthic meiofauna assemblages of the Egyptian coasts along the Red Sea are described in relation to abiotic variables. Sediment samples were collected seasonally from three stations chosen along the Red Sea to observe the meiofaunal community structure, its temporal distribution and vertical fluctuation in relation to environmental conditions of the Red Sea marine ecosystem. The temperature, salinity, pH, dissolved oxygen, and redox potential were measured at the time of collection. The water content of the sediments, total organic matters and chlorophyll a values were determined, and sediment samples were subjected to granulometric analysis. A total of 10 meiofauna taxa were identified, with the meiofauna being primarily represented by nematodes (on annual average from 42% to 84%), harpacticoids, polycheates and ostracodes; and the meiofauna abundances ranging from 41 to 167 ind./10 cm(2). The meiofaunal population density fluctuated seasonally with a peak of 192.52 ind./10 cm(2) during summer at station II. The vertical zonation in the distribution of meiofaunal community was significantly correlated with interstitial water, chlorophyll a and total organic matter values. The present study indicates the existence of the well diversified meiofaunal group which can serve as food for higher trophic levels in the Red Sea interstitial environment. PMID:26150753

  1. Effect of the brown shrimp Crangon crangon L. on endobenthic macrofauna, meiofauna and meiofaunal grazing rates

    NASA Astrophysics Data System (ADS)

    Nilsson, Per; Sundbäck, Kristina; Jönsson, Benno

    The effect of natural densities (50 and 100 ind·m -2) of juvenile (<20 mm) Crangon crangon on abundance of endobenthic macrofauna and meiofauna and on meiofaunal grazing rates was investigated in two experiments using an outdoor flow-through system with sandy sediment. The experiments differed in duration (3 wk and 7.5 wk), and in time of the year (August - September and July - August). Macrofaunal biomass differed by a factor of 10 between the experiments, and was depressed by shrimp in both experiments. Neither total meiofaunal biomass, nor the biomass of the dominant taxon (nematodes), was significantly affected by the presence of Crangon in the shorter experiment. However, harpacticoid copepods and other meiofauna taxa (mainly ostracods, foraminiferans and juvenile bivalves) decreased in the presence of Crangon. In the longer experiment, no significant effect of Crangon on meiofauna was seen, and the biomass of most meiofaunal groups increased in all treatments. Meiofaunal grazing rates in microalgae and bacteria, measured with a dual-labelling method, using 14C-bicarbonate and [methyl- 3

  2. Sedimentological Aspects and Diagenetic Alterations of Beda "C" , Southwestern Sirt Basin, Libya

    NASA Astrophysics Data System (ADS)

    Hlal, Osama

    2015-04-01

    The rock sequence of Tertiary Lower Beda Formation Beda "C" of southwest NC74B block in Sirt Basin has considered subdivided into facies and subfacies . These facies are dominated by muddy carbonates, such as skeletal mudstones, wackestones, and packstones with dolomites and anhydrite. Rock textures, faunal assemblages and sedimentary structures suggest open to partly open to shallow marine, lagoonal shelf , and upper subtidal to lower supratidal (Preitidal) environments. The Beda "C" Member represents a shallowing-upward sequence typical of lagoonal and tidal flat environments marked at the top by sabkha and brackish-water sediments. Petrographic and microfossils studies have been made by means of microscopic examination of (24) thin section. Microfossils include benthonic foraminifera, in addition ostracods, molluscs, echinoderms, and bryozoans. Dolomite, where present, is finely crystalline and an early replacement product. Anhydrite occurs as nodular, indicating supratidal sabkha deposition. Compaction, micritzation , dolomitization, cementation, and dissolution resulted in alteration and obliteration of primary sedimentary structures of the Beda "C" Member facies and subfacies. The study area is marked by several horsts and grabens; due to extensional tectonic activity. The area was tectonically active throughout the Tertiary period. Primary porosity is mainly interagranular, and dissolution diagenetic processes are significant enhancing the porosity. Primary porosity is intergranular and intragranular, and secondary processes are characterized by dissolution, intercrystalline, fracture. Diagenesis, through solution leaching and dolomitization, contributed greatly to development of porosity. Anhydrite occurs as replacement in top Member indicating supratidal deposition using a regular petrographic microscope, SEM and XRD analysis.

  3. Spatial and temporal changes in prevalence of a cloacal cestode in wintering waterfowl along the Gulf Coast of Texas.

    PubMed

    Haukos, David A; Neaville, Jim

    2003-01-01

    The cloacal cestode Cloacotaenia megalops is one of the most common helminths of waterfowl. We investigated the effect of this parasite on the body condition of wintering waterfowl populations and compared prevalence among age-sex classes, over time and between habitat types on the upper Gulf Coast of Texas (USA) from October 1986-February 2000. Greater than 9,500 birds of 25 waterfowl species were examined for the parasite. There was no statistical difference (P > 0.05) in body condition between birds with and without the parasite. Average prevalence was lowest for geese (mean = 3.7%) versus 21 to 71% in duck species. Average prevalence was similar (P = 0.81) between diving ducks (mean = 46.9%) and puddle ducks (mean = 43.9%). Prevalence varied among age-sex classes and was related to sex rather than age. Variation among age-sex classes suggests differences in diet between sexes of duck species on the wintering grounds. There was no evidence for declining prevalence over the wintering period. Prevalence differed (P < 0.05) between collection sites, and thereby habitat types, for several species. Temporal trends indicate stable prevalence of C. megalops for diving ducks and increasing prevalence for puddle ducks. The increasing trend for puddle ducks may indicate declining habitat conditions resulting in increased exposure to the intermediate ostracod host. PMID:12685079

  4. Statistically significant faunal differences among Middle Ordovician age, Chickamauga Group bryozoan bioherms, central Alabama

    SciTech Connect

    Crow, C.J.

    1985-01-01

    Middle Ordovician age Chickamauga Group carbonates crop out along the Birmingham and Murphrees Valley anticlines in central Alabama. The macrofossil contents on exposed surfaces of seven bioherms have been counted to determine their various paleontologic characteristics. Twelve groups of organisms are present in these bioherms. Dominant organisms include bryozoans, algae, brachiopods, sponges, pelmatozoans, stromatoporoids and corals. Minor accessory fauna include predators, scavengers and grazers such as gastropods, ostracods, trilobites, cephalopods and pelecypods. Vertical and horizontal niche zonation has been detected for some of the bioherm dwelling fauna. No one bioherm of those studied exhibits all 12 groups of organisms; rather, individual bioherms display various subsets of the total diversity. Statistical treatment (G-test) of the diversity data indicates a lack of statistical homogeneity of the bioherms, both within and between localities. Between-locality population heterogeneity can be ascribed to differences in biologic responses to such gross environmental factors as water depth and clarity, and energy levels. At any one locality, gross aspects of the paleoenvironments are assumed to have been more uniform. Significant differences among bioherms at any one locality may have resulted from patchy distribution of species populations, differential preservation and other factors.

  5. Food of the bloater, Coregonus hoyi, in Lake Michigan

    USGS Publications Warehouse

    Wells, LaRue; Beeton, Alfred M.

    1963-01-01

    Stomachs were examined from 1,469 Lake Michigan bloaters, Coregonus [Leucichthys] hoyi, greater than 7 inches long which contained identifiable food. An additional 461 ciscoes less than 7 inches long were incorporated into the study; these latter fish were not positively identified, but most of them undoubtedly were bloaters. The specimens were caught in bottom nets except for 49, all less than 6 inches long, taken in midwater trawls. Lake Michigan bloaters under 7 inches long depend heavily on zooplankton. Those larger than 7 inches feed predominantly on Pontoporeia affinis and Mysis relicta, although fish of the 7.0- to 7.9-inch size range commonly eat zooplankton, expecially in shallower water. Generally, Mysis becomes more important, and Pontoporeia less so, as the depth increases and as the season progresses from spring to fall. Incidence of Pontoporeia increases and that of Mysis declines as the fish size increases. Other food items, in decreasing order of importance, are fingernail clams, midges (all stages of development), fish eggs, ostracods, and miscellaneous adult and immature insects other than midges.

  6. Mid-Miocene cooling and the extinction of tundra in continental Antarctica

    PubMed Central

    Lewis, Adam R.; Marchant, David R.; Ashworth, Allan C.; Hedenäs, Lars; Hemming, Sidney R.; Johnson, Jesse V.; Leng, Melanie J.; Machlus, Malka L.; Newton, Angela E.; Raine, J. Ian; Willenbring, Jane K.; Williams, Mark; Wolfe, Alexander P.

    2008-01-01

    A major obstacle in understanding the evolution of Cenozoic climate has been the lack of well dated terrestrial evidence from high-latitude, glaciated regions. Here, we report the discovery of exceptionally well preserved fossils of lacustrine and terrestrial organisms from the McMurdo Dry Valleys sector of the Transantarctic Mountains for which we have established a precise radiometric chronology. The fossils, which include diatoms, palynomorphs, mosses, ostracodes, and insects, represent the last vestige of a tundra community that inhabited the mountains before stepped cooling that first brought a full polar climate to Antarctica. Paleoecological analyses, 40Ar/39Ar analyses of associated ash fall, and climate inferences from glaciological modeling together suggest that mean summer temperatures in the region cooled by at least 8°C between 14.07 ± 0.05 Ma and 13.85 ± 0.03 Ma. These results provide novel constraints for the timing and amplitude of middle-Miocene cooling in Antarctica and reveal the ecological legacy of this global climate transition. PMID:18678903

  7. Evidence at Lomax, Illinois, for mid-Wisconsin (~40,000 yr B.P.) position of the Des Moines Lobe and for diversion of the Mississippi River by the Lake Michigan Lobe (20,350 yr B.P.)

    USGS Publications Warehouse

    Curry, B. Brandon

    1998-01-01

    An abrupt change in environment from a wetland to a deeper slackwater lake at 20,345 ?? 85 yr B.P. occurred in a second-order valley tributary to the Mississippi River near Lomax, Illinois. The age of this shift is associated with the overflow of glacial Lake Milan and diversion of the Mississippi River from the Princeton Valley (Rock Island to Peoria) to its present course (Rock Island to St. Louis). The diversion occurred due to blockage of the Princeton Valley segment of the ancient Mississippi River by the Lake Michigan Lobe, impoundment of glacial Lake Milan, and eventual overflow of the lake southwest of Rock Island across a former drainage divide near Andalusia, Illinois. Fossil ostracode assemblages in the slackwater sediment at Lomax indicate changes in the post-diversion, full-glacial paleohydrology and, based on multivariate analysis, hint at the area's paleoclimate. An older part of the succession at Lomax is consistent with glaciation in the upper Iowa River basin about 40,000 yr B.P. Aggradation of sediment rich in coarse silt is attributed to a response of the ancient Iowa River basin associated with deposition of the glacigenic Sheldon Creek Formation by the Des Moines Lobe.

  8. Effects of coal mine drainage on the water quality of small receiving streams in Washington, 1975-77

    USGS Publications Warehouse

    Packard, F.A.; Skinner, E.L.; Fuste, L.A.

    1988-01-01

    Drainage from abandoned coal mines in western and central Washington has minimal environmental impact. Water quality characteristics that have the most significant environmental impact are suspended sediment and turbidity. Water quality data from 51 abandoned coal mines representing 11 major coal bearing areas indicate that less than 1% of the mine drainage has a pH of 4.5 or less. Fifty percent of the drainage is alkaline and has pH 7.0 and greater, and about 95% of the drainage has pH 6.0 and greater. Less than 2% is acidified to a pH of 5.6, a point where water and free (atmospheric) carbon dioxide are in equilibrium. The area where pH 5.6 or less is most likely to occur is in the Centralia/Chehalis mine district. No significant difference in diversity of benthic organisms was found between stations above and below the mine drainage. However, within the 50-ft downstream reach ostracods were more abundant than above the mine drainage and mayflies, stoneflies, and caddisflies were less abundant than at the control site. Correlations to water quality measurements show that these faunal changes are closely associated with iron and sulfate concentrations. (USGS)

  9. First glimpse into Lower Jurassic deep-sea biodiversity: in situ diversification and resilience against extinction

    PubMed Central

    Thuy, Ben; Kiel, Steffen; Dulai, Alfréd; Gale, Andy S.; Kroh, Andreas; Lord, Alan R.; Numberger-Thuy, Lea D.; Stöhr, Sabine; Wisshak, Max

    2014-01-01

    Owing to the assumed lack of deep-sea macrofossils older than the Late Cretaceous, very little is known about the geological history of deep-sea communities, and most inference-based hypotheses argue for repeated recolonizations of the deep sea from shelf habitats following major palaeoceanographic perturbations. We present a fossil deep-sea assemblage of echinoderms, gastropods, brachiopods and ostracods, from the Early Jurassic of the Glasenbach Gorge, Austria, which includes the oldest known representatives of a number of extant deep-sea groups, and thus implies that in situ diversification, in contrast to immigration from shelf habitats, played a much greater role in shaping modern deep-sea biodiversity than previously thought. A comparison with coeval shelf assemblages reveals that, at least in some of the analysed groups, significantly more extant families/superfamilies have endured in the deep sea since the Early Jurassic than in the shelf seas, which suggests that deep-sea biota are more resilient against extinction than shallow-water ones. In addition, a number of extant deep-sea families/superfamilies found in the Glasenbach assemblage lack post-Jurassic shelf occurrences, implying that if there was a complete extinction of the deep-sea fauna followed by replacement from the shelf, it must have happened before the Late Jurassic. PMID:24850917

  10. The isolation of the Pannonian basin (Central Paratethys): New constraints from magnetostratigraphy and biostratigraphy

    NASA Astrophysics Data System (ADS)

    ter Borgh, Marten; Vasiliev, Iuliana; Stoica, Marius; Knežević, Slobodan; Matenco, Liviu; Krijgsman, Wout; Rundić, Ljupko; Cloetingh, Sierd

    2013-04-01

    In this paper we establish when and how the Pannonian basin and associated Central Paratethys basins were isolated from the remainder of the Paratethys, a system of back-arc basins and inland seas that once extended over a large part of Europe. The isolation, which occurred at the beginning of the Late Miocene, is marked by a paleoenvironmental change from marine to fresh water conditions that caused the regional Sarmatian-Pannonian Extinction Event. It also had significant paleogeographical implications for the basin fill and for sedimentary transport across the Carpathian Mountains. The exact age of and cause for the isolation are still subject to debate. Here, we use magnetostratigraphic dating coupled to ostracod and mollusc biostratigraphy to establish the isolation age of the Pannonian basin. We dated the isolation of the Pannonian basin at 11.63 ± 0.04 Ma in a section on the northern flank of the Fru\\vska Gora inselberg (northern Serbia). This age is in line with recent results from the Vienna basin but predates the isolation of the Transylvanian by 0.33 Myr, suggesting that isolation took place in two steps. We conclude that the uplift of the Carpathian Mountains caused the isolation but that eustatic sea level fluctuations may have had a minor influence as well.

  11. Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath

    NASA Astrophysics Data System (ADS)

    Song, Haijun; Wignall, Paul B.; Chu, Daoliang; Tong, Jinnan; Sun, Yadong; Song, Huyue; He, Weihong; Tian, Li

    2014-02-01

    The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

  12. No slave to sex.

    PubMed

    Schön, Isabelle; Martens, Koen

    2003-04-22

    Fully asexual lineages cannot purge accumulating mutations from their genome through recombination. In ancient asexuals that have persisted without sex for millions of years, this should lead to high allelic divergences (the 'Meselson effect') as has been shown for bdelloid rotifers. Homogenizing mechanisms can counter this effect, resulting in low genetic diversity within and between individuals. Here, we show that the ancient asexual ostracod species Darwinula stevensoni has very low nucleotide sequence divergence in three nuclear regions. Differences in genetic diversity between embryos and adults furthermore indicate that up to half of the observed genetic changes in adults can be caused by somatic mutations. Likelihood permutation tests confirm the presence of gene conversion in the multi-copy internal transcribed spacer sequence, but reject rare or cryptic forms of sex as a general explanation for the low genetic diversity in D. stevensoni. Other special mechanisms (such as highly efficient DNA repair) might have been selected for in this ancient asexual to overcome the mutational load and Muller's ratchet. In this case, our data support these hypotheses on the prevalence of sex, even if the two extant ancient asexual groups (bdelloids and darwinulids) seem to follow opposite evolutionary strategies. PMID:12737661

  13. Strontium isotopic-paleontological method as a high-resolution paleosalinity tool for lagoonal environments

    NASA Astrophysics Data System (ADS)

    Reinhardt, Eduard G.; Stanley, Daniel Jean; Patterson, R. Timothy

    1998-11-01

    A combined strontium isotopic (87Sr/86Sr) and paleontological method is newly applied to a modern lagoon in Egypt's Nile River delta to test its applicability as a paleosalinity proxy. Analyses of 22 surficial samples collected throughout the lagoon include 81 Sr isotopic analyses of mollusks, foraminifera, ostracods, barnacles, bryozoans, serpulid worm tubes, pore water, and gypsum crystals. Two salinity groups are distinguished in each sample: a lower salinity group (˜1 ppt) mixed with a higher salinity group (˜3 10 ppt) that, respectively, are interpreted as the modern biocoenosis and an older relict fauna. The relict fauna denotes higher salinity conditions in the lagoon prior to closure of the Aswan High Dam (1964), and the modern fauna records freshening of the lagoon. Recent decreased salinity is a response to regulated Nile River flow and increased discharge into Manzala of fresh water via canals and drains. Quantification of this short-term salinity change holds promise for study of modern lagoons in other world settings, and may provide paleoclimatic information for older lagoon sequences in the Nile River delta and the geologic record.

  14. Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

    PubMed

    Castenholz, Richard W

    2015-01-01

    Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments. PMID:25633225

  15. Feeding ecology of Liza spp. in a tidal flat: Evidence of the importance of primary production (biofilm) and associated meiofauna

    NASA Astrophysics Data System (ADS)

    Carpentier, Alexandre; Como, Serena; Dupuy, Christine; Lefrançois, Christel; Feunteun, Eric

    2014-09-01

    Grey mullets are unique among temperate-region fish species in their ability to feed on mudflat biofilm. In this study, we examined mullet feeding strategies on biofilm and associated meiofauna by using a diet study and stable isotope analysis to explore functional interactions between mullets and tidal flats. A stomach vacuity investigation showed that mullets did not import any materials from subtidal areas into the mudflat but exported mud, biofilm, and associated meiofauna. The results of mullet stomach content and fecal analyses, when compared to the availability of tidal flat resources, showed evidence of mullets' ability to ingest and assimilate biofilm and to concentrate major meiofauna grazers such as nematodes, copepods and, secondarily, foraminifers and ostracods. Isotopic ratios confirmed diet investigations, and as recently shown in salt marsh habitats, mullets exhibited an intermediate trophic position, supporting the hypothesis that they can assimilate both biofilm and major meiofauna grazers. The function of the tidal flat as a feeding habitat for gray mullets and the role of mullets as the main export pathway of biofilm from tidal flat ecosystems are discussed.

  16. An updated checklist of the Recent non-marine Ostracoda (Crustacea) of Iran, with a redescription of Eucypris mareotica (Fischer, 1855).

    PubMed

    Rasouli, Hamidreza; Scharf, Burkhard; Meisch, Claude; Aygen, Cem

    2016-01-01

    An updated checklist of the extant non-marine Ostracoda of Iran, with 74 species in all, is presented, based on literature and new collections made in May 2011. The occurrence of 19 non-marine ostracod species recovered from 10 localities in May 21-26, 2011 is reported together with ecological data. Eucypris kerkyrensis Stephanides, 1937, Ilyocypris inermis Kaufmann, 1900, Psychrodromus fontinalis Wolf, 1920, and P. olivaceus (Brady & Norman, 1889) are new to the fauna of Iran. Eucypris mareotica (Fischer, 1855) is redescribed and its taxonomic position is discussed. It is shown that E. mareotica-synonymous with E. inflata-does not belong to the genus Eucypris sensu stricto, and even not to the subfamily Eucypridinae; as its characters do not fit any available genus, the species is therefore provisionally left in the genus Eucypris at present. Eucypris mongolica (Daday, 1909) is proposed to be considered an infraspecific variety of E. mareotica. The following new combination is here proposed: Strandesia ambigua (Ghetti, 1972) nov. comb. PMID:27615839

  17. Revised Chronology for the Mio-Pliocene Successions of the Eastern Paratethys: Towards a Better Understanding of Paleoenvironmental Change

    NASA Astrophysics Data System (ADS)

    Krijgsman, W.; Chang, L.; Baak, C. V.; Palcu, D.; Vasiliev, I.

    2014-12-01

    Paratethys is a large epicontinental sea, stretching from Germany to China at the beginning of the Oligocene (~34 Myr ago), that progressively retreated by a complex combination of basin infill, glacio-eustatic sea-level lowering and tectonic uplift to its present-day remnants: Black Sea, Caspian Sea and Aral Lake. Paratethys experienced major paleoenvironmental changes towards anoxic, hypersaline, and fresh water conditions. An accurate geological time scale (GTS) is crucial to understand the timing and rates of these change and to determine the underlying mechanisms. Geological time scales for the Paratethys region are notoriously controversial and encompass mainly regional stages, which are all defined on the basis of characteristic faunal assemblages (mainly mollusks and ostracods) endemic to the Paratethys Sea. During the last decade, we have performed numerous integrated magneto-biostratigraphic studies on the Mio-Pliocene sedimentary successions of the Eastern Paratethys, which resulted in revised chronological frameworks for the Dacian, Black Sea and Caspian Sea basins. This allows high-resolution stratigraphic correlations between the individual Paratethys subbasins and with the Mediterranean successions and help to better understand the dramatic paleoenvironmental changes in the region, such as the Messinian Salinity Crisis. Rock magnetic analyses of the sedimentary sequences of the Paratethys indicate that greigite is the main magnetic carrier and that a range of magnetic properties cannot be explained by the presence of diagenetic greigite, but are instead consistent with those expected for a biogenetic (bacterial) origin.

  18. Sequence stratigraphy of the Lower Triassic Sinbad Formation, San Rafael Swell, east-central, Utah

    SciTech Connect

    Goodspeed, T.H.; Elrick, M. . Dept. of Earth and Planetary Sciences); Lucas, S.G. )

    1993-04-01

    The Lower Triassic Sinbad Fm (20--30 m thick) in the San Rafael Swell of east-central Utah is high energy carbonate deposits that conformably overlie tidal flat/fluvial channel deposits of the Black Dragon Fm. The Torrey Fm conformably overlies the Sinbad Fm and consists primarily of siliciclastic tidal flat and fluvial deposits. Five facies (in ascending order) are characteristic of the Sinbad Fm: (1) bioturbated calcisiltite with calcite-replaced evaporite nodules and ripple laminations, (2) skeletal-oolitic-intraclastic packstone and grainstone, (3) slightly bioturbated, mechanically laminated, pelletal calcisiltite (5) trough cross-bedded, peloidal to oolitic grainstone, and (5) thin-bedded, skeletal-pelletal-oolitic grainstone with mud to wackestone drapes. Regional facies relationships of the Sinbad Fm indicate initial deepening followed by shallowing. The skeletal-intraclastic packstone and grainstone facies represents maximum flooding. This facies thickens to the northwest and contains an open marine molluscan fauna of ammonites, bivalves, gastropods and scaphopods. The ammonites are indicative of the Tardus Zone of late Smithian age. Deposits above the maximum flooding zone (MFZ) are restricted foreshoal, pelletal calcisiltite, oolitic shoal, and backshoal skeletal-oolitic (with a restricted fauna of molluscs and ostracods) deposits. This shallowing-upward sequence represents the early HST. The Sinbad Fm represents the MFZ and early HST of a 150-m-thick depositional sequence of rocks with the Black Dragon FM representing the TST, and the Torrey Fm representing the late HST.

  19. [Spatio-temporal variation of subtidal meiofauna in a sandy beach from Northeastern Venezuela].

    PubMed

    Arana, Ildefonso Liñero; Ojeda, Sol; Amaro, María Elena

    2013-03-01

    Meiofauna organisms that play an important role in the trophic ecology of soft bottom benthos, have short life cycles and they respond quickly to disturbance and pollution. The present study shows the spatio-temporal variation ofsubtidal meiofauna (metazoans passing a 500im sieve but retained on meshes of 40-63micro m) in four shallow subtidal stations. Samples were taken in the sandy beach of San Luis, in the Northeastern coast of Venezuela, from October 2005 until September 2006. For this, three replicate sediment core samples (4.91cm2), were collected monthly to a depth of 10cm into the sediment, and preserved in 6% formalin stained with rose Bengal. Specimens of 14 meiofaunal groups (Foraminifera excluded) were collected, being the nematodes, ostracods and harpacticoid copepods the most abundant. Monthly density was comprised between 64 and 503ind./10cm2, and mean density of stations between 173 and 449ind./10cm2. There is a trend of low densities from October to February (end of the rainy season until the middle of the dry season). The San Luis beach control of the meiofaunal community is shared by climatic conditions and by the biology of the species found. The meiofauna mean density in San Luis beach (263ind./10cm2) was low when compared to other studies in tropical areas. PMID:23894963

  20. Late Stage 5 Glacio-isostatic Sea in the St. Lawrence Valley, Canada and United States

    USGS Publications Warehouse

    Occhietti, S.; Balescu, S.; Lamothe, M.; Clet, M.; Cronin, T.; Ferland, P.; Pichet, P.

    1996-01-01

    Although post-glacial marine sediments of late Wisconsinan and early Holocene age are common in eastern Canada and the northeastern United States, remnants of older Pleistocene marine sediments are scarce. A fossiliferous marine clay that predates the classical Wisconsinan was recently discovered in the St. Lawrence Valley. A dominantly estuarine environment is inferred from the geochemistry of the shells (??18O = -7.1) and from benthic foraminifer and ostracode assemblages. The clay indicates a marine invasion (Cartier Sea) shallower and probably shorter than that during the upper late Wisconsinan Champlain Sea episode (12,000-9,500 yr B.P.). The pollen content shows that regional vegetation during the marine episode began as open tundra, then became a Betula and Alnus crispa forest, reached a climatic optimum with Quercus, Corylus, and Abies, and concluded as a Pinus/Picea boreal forest. A corrected infrared stimulated luminescence age of 98,000 ?? 9000 yr is compatible with the epimerization ratio of shells. The Cartier Sea resulted from a post-glacial glacio-isostatic marine invasion in the St. Lawrence lowlands. It probably occurred during late stage 5 and is tentatively assigned to the transition of oxygen isotope substages 5b/5a. This marine episode dates to stage 5 of the preceding continental glacier which extended to middle latitudes in NE America. ?? 1996 University of Washington.

  1. Facies analysis and sequence stratigraphy of the Cenomanian-Turonian mixed siliciclastic-carbonate sediments in west Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Anan, Tarek I.

    2014-06-01

    The unconformity bounded Cenomanian-Turonian succession in west Sinai is subdivided into three formations: the Raha, Abu Qada, and Wata. These rock units were deposited in a mixed siliciclastic-carbonate system on a ramp setting. The studied ramp only includes inner and mid-ramp facies, whereas the outer ramp facies occurs in northern Sinai. Four sequence boundaries (SB) were recognized in the studied formations due to the presence of subaerial exposure or flooding events in the facies stacking pattern. The first and last sequence boundaries (SB1 and SB4) might be considered as Type 1 sequence boundary attributable to the presence of widespread erosion. It is difficult to determine type of the second and third sequence boundaries (SB2 and SB3) because of their minor unconformity and minimal erosion. Determination of systems tracts within the Wata Formation is debatable owing to the action of dolomitization that has destroyed both original components and sedimentary structures. The lowstand systems tracts of the recorded sequences are characterized by sandstones, siltstones, and sandy shales, while fossiliferous shale and limestone with oysters prevailed during sea level rise. The highstand systems tracts are generally characterized by shallow intertidal and subtidal deposits that are made up of abundant oyster wackestones with benthic foraminifera and ostracods.

  2. Impact of millennial mining activities on sediments and microfauna of the Tinto River estuary (SW Spain).

    PubMed

    Ruiz, F; Borrego, J; González-Regalado, M L; López González, N; Carro, B; Abad, M

    2008-07-01

    In this paper, we analyze two short cores collected in the Tinto estuary (SW Spain), and describe the palaeoenvironmental evolution of this area during the last two millennia, along with the influence of historical mining activities and recent industrial pollution on sediments and microfauna (foraminifera and ostracoda). Although there were no significant changes in the distribution of microorganisms, a first pollution period (0-150 AD) was recorded in high sediment pollution by Cu in the shallow palaeochannels of the middle estuary. During this period and the following 1700 years, tolerant pioneer species of both foraminifera and ostracoda were found predominantly in the inner, protected areas of the estuary, while the bottom sediments were subjected to high hydrodynamic gradients, and consequently showed lower density and diversity of organisms. In the last 150 years, acid mine drainage processes, introduction of a new mining period, and the polluted inputs derived from two industrial processes resulted in increased heavy metal contamination of the bottom sediments, and corresponding extirpation of ostracodes and restriction of foraminifers to the inner zones of the estuary. PMID:18538354

  3. Environmental transformations and cultural changes: A multidisciplinary case study for the Late Glacial and Final Palaeolithic from Northern Germany

    NASA Astrophysics Data System (ADS)

    Turner, F.; Tolksdorf, J. F.; Viehberg, F.; Schwarz, A.; von Bramann, U.; Bittmann, F.; Kaiser, K.; Schwalb, A.; Staesche, U.; Breest, K.; Pott, R.; Veil, S.

    2012-04-01

    In contrast to younger periods, studies integrating archaeological and environmental records for the Palaeolithic are still rare. Especially our knowledge about interactions between the drastic climatic/environmental changes and cultural developments during the Late Glacial is very limited. This multidisciplinary case study from river Jeetzel, a western Elbe tributary in Northern Germany, combines high resolution palaeoenvironmental investigations with fine-scaled archaeological research on stratified and surface sites. Various dating methods (palynostratigraphy, radiocarbon- and OSL-dating) and analyses of environmental and climatological proxies (pollen and plant macro-remains, ostracods, diatoms and green algae) on river palaeochannel sediments allow detailed reconstruction of interactions between Late Glacial climate, vegetation and fluvial developments. Biostratigraphical analyses on stratified archaeological sites and dating of charcoal / bone fragments from artefact scatters place the Late Palaeolithic occupation of Early Federmesser groups in an environmental context. Thus the former production of hitherto unknown amber art (amongst others a figurine representing a moose) can be ascribed to the Older Dryas and Early Allerød, which are the periods of main Late Glacial afforestation. Therewith our investigations suggest that Final Palaeolithic cultural changes may have been triggered by climatic and environmental transformations.

  4. Sea-level and environmental changes since the last interglacial in the Gulf of Carpentaria, Australia: an overview

    USGS Publications Warehouse

    Chivas, Allan R.; Garcı́a, Adriana; van der Kaars, Sander; Couapel, Martine; Holt, Sabine; Reeves, Jessica M.; Wheeler, David J.; Switzer, Adam D.; Murray-Wallace, Colin V.; Banerjee, Debabrata; Price, David M.; Wang, Sue X.; Pearson, Grant; Edgar, N. Terry; Beaufort, Luc; de Deckker, Patrick; Lawson, Ewan; Cecil, C. Blaine

    2001-01-01

    The Gulf of Carpentaria is an epicontinental sea (maximum depth 70 m) between Australia and New Guinea, bordered to the east by Torres Strait (currently 12 m deep) and to the west by the Arafura Sill (53 m below present sea level). Throughout the Quaternary, during times of low sea-level, the Gulf was separated from the open waters of the Indian and Pacific Oceans, forming Lake Carpentaria, an isolation basin, perched above contemporaneous sea-level with outlet channels to the Arafura Sea. A preliminary interpretation is presented of the palaeoenvironments recorded in six sediment cores collected by the IMAGES program in the Gulf of Carpentaria. The longest core (approx. 15 m) spans the past 130 ka and includes a record of sea-level/lake-level changes, with particular complexity between 80 and 40 ka when sea-level repeatedly breached and withdrew from Gulf/Lake Carpentaria. Evidence from biotic remains (foraminifers, ostracods, pollen), sedimentology and geochemistry clearly identifies a final marine transgression at about 9.7 ka (radiocarbon years). Before this transgression, Lake Carpentaria was surrounded by grassland, was near full, and may have had a surface area approaching 600 km×300 km and a depth of about 15 m. The earlier rise in sea-level which accompanied the Marine Isotopic Stage 6/5 transgression at about 130 ka is constrained by sedimentological and biotic evidence and dated by optical- and thermoluminescence and amino acid racemisation methods.

  5. Western Arctic Ocean temperature variability during the last 8000 years

    USGS Publications Warehouse

    Farmer, Jesse R.; Cronin, Thomas M.; De Vernal, Anne; Dwyer, Gary S.; Keigwin, Loyd D.; Thunell, Robert C.

    2011-01-01

    We reconstructed subsurface (∼200–400 m) ocean temperature and sea-ice cover in the Canada Basin, western Arctic Ocean from foraminiferal δ18O, ostracode Mg/Ca ratios, and dinocyst assemblages from two sediment core records covering the last 8000 years. Results show mean temperature varied from −1 to 0.5°C and −0.5 to 1.5°C at 203 and 369 m water depths, respectively. Centennial-scale warm periods in subsurface temperature records correspond to reductions in summer sea-ice cover inferred from dinocyst assemblages around 6.5 ka, 3.5 ka, 1.8 ka and during the 15th century Common Era. These changes may reflect centennial changes in the temperature and/or strength of inflowing Atlantic Layer water originating in the eastern Arctic Ocean. By comparison, the 0.5 to 0.7°C warm temperature anomaly identified in oceanographic records from the Atlantic Layer of the Canada Basin exceeded reconstructed Atlantic Layer temperatures for the last 1200 years by about 0.5°C.

  6. Pliocene three-dimensional global ocean temperature reconstruction

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.; Foley, K.M.

    2009-01-01

    The thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water temperature estimates from 27 locations produced using Mg/Ca paleothermometry based upon the ostracod genus Krithe. Deep water temperature estimates are skewed toward the Atlantic Basin (63% of the locations) and represent depths from 1000m to 4500 m. This reconstruction, meant to serve as a validation data set as well as an initialization for coupled numerical climate models, assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic Bottom Water (AABW) production (relative to present day) as well as possible changes in the depth of intermediate waters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.

  7. Late Triassic (Norian) foraminifera from Hopen Island, Barents Sea, paleoenvironmental significance and sequence stratigraphy implications

    NASA Astrophysics Data System (ADS)

    Cetean, Claudia; Paterson, Niall; Mangerud, Gunn

    2015-04-01

    The dark laminated mudstones of the Flatsalen Formation exposed on Hopen Island, in the Barents Sea record an early Norian transgression. At the base of the Formation, the Slottet Beds are considered to represent a transgressive lag deposit overlaid by the finer sediments which preserve agglutinated foraminifera, radiolaria and ostracod casts in the Lyngefjellet outcrop. During the transgressive phase the maximum abundance of foraminifera was noted, with benthonic assemblages dominated by small size Trochammina and Ammodiscus species. These types of assemblages are indicative of neritic depositional settings in the boreal domain, probably controlled by influxes of fresh water from adjacent land masses (Nagy et al., 2010). An influx of radiolaria, assumed to represent a maximum flooding surface (Mfs), indicating the onset of fully marine conditions was observed higher in the section, with marine microplankton peaking 9m higher. The decoupling between marine benthonic and planktonic microfossils is believed to be a consequence of a stratified water column. The Mfs is coeval with a marked decrease in the abundance and diversity of foraminifera and a change from epifauna to infauna - dominated agglutinated assemblages suggesting bottom waters hypoxia. In the first stage of marine regression, unstable palaeoenvironmental conditions are inferred, based on a gradual increase in dominance of few taxa, including opportunistic species of Glomospira. Nagy, J., Hess, S. and Alve, E., 2010. Environmental significance of foraminiferal assemblages dominated by small-sized Ammodiscus and Trochammina in Triassic and Jurassic delta-influenced deposits. Earth-Science Reviews, 99, 31-49.

  8. Spiral phosphatic coprolites from the Pennsylvanian of southeastern Ohio

    SciTech Connect

    Krishnaswamy, R.; Fugitt, F.L.; Kidder, D.L. . Dept. of Geological Sciences)

    1994-04-01

    Pennsylvanian-age phosphatic coprolites are very well-preserved in a thin black shale near the middle of the Conemaugh Group approximately 3 miles southwest of Athens Ohio. Coprolite surface textures are predominantly botryoidal, although smooth surfaces are also present. Spiral patterns are common on exterior surfaces along the long axis of the coprolite, and the spiral structure is well-preserved within some coprolites. Outer surface colors range from brownish gray to dark gray. Rollers and disks comprise the dominant coprolite shape, whereas blades and spheres are far less prevalent. Coprolites are between 0.3 and 1.0 cm long, and width ranges from 0.2 to 0.62 cm. Coprolite interiors are primarily microcrystalline phosphate that hosts phosphatic brachiopod fragments with exquisitely preserved microstructure. In some cases the phosphate matrix preserves microstructure. In some cases the phosphate matrix preserves a peloidal fabric, and some coprolites display shrinkage cracks filled with microcrystalline quartz. Dominance of the host shale fauna by ostracodes and Xenocanthus teeth suggests a restricted fauna. The narrow range of coprolite widths supports this interpretation. The authors expect these coprolites to be preferentially enriched in middle rare earth elements after the fashion of other Paleozoic fecal phosphates.

  9. Fossil invertebrates records in cave sediments and paleoenvironmental assessments - a study of four cave sites from Romanian Carpathians

    NASA Astrophysics Data System (ADS)

    Moldovan, O. T.; Constantin, S.; Panaiotu, C.; Roban, R. D.; Frenzel, P.; Miko, L.

    2016-01-01

    Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new to science, and most of them are indicative for either warm and/or cold stages or dry and/or wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures and hydraulic regimes could be gathered. This paper analyzes the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.

  10. Late Quaternary continental and marine sediments of northeastern Buenos Aires province (Argentina): Fossil content and paleoenvironmental interpretation

    NASA Astrophysics Data System (ADS)

    Fucks, Enrique; Aguirre, Marina; Deschamps, Cecilia M.

    2005-10-01

    Abundant invertebrate and vertebrate fossil remains that exhibit excellent preservation and were collected from deposits of both continental and marine origins at Pilar (Buenos Aires, Argentina) add paleoenvironmental data from the northeastern Buenos Aires province area linked to sea-level oscillations and climate variability since approximately 120 ka BP (marine oxygen isotope stage [MOIS] 5e). Two new fossiliferous localities discovered in the Luján River Valley allow for detailed geological studies and new dating of molluscan shells and bones. The studies suggest salinity changes during the Last Interglacial (8 m above m.s.l., min. 14C>40 ka) and the mid-Holocene transgression (5 m above m.s.l., 7-3 14C ka BP) compared with the modern pattern along the adjacent littoral (Río de la Plata). The marine sequences represent the innermost boundary of the sea-level transgression in that area and contain a biogenic record (bivalves, gastropods, forams, ostracods) that indicates marginal marine environments (higher salinity than at present). Vertebrates and molluscs from the continental sequence suggest a freshwater habitat in which remains of marine fish must be allochthonous, probably incorporated by postmortem fluvial transport to the final depositional environment.

  11. A new turtle from the Upper Cretaceous Bauru Group of Brazil, updated phylogeny and implications for age of the Santo Anastácio Formation

    NASA Astrophysics Data System (ADS)

    Menegazzo, Mirian Costa; Bertini, Reinaldo José; Manzini, Flávio Fernando

    2015-03-01

    A new Podocnemidinura specimen from the Upper Cretaceous Bauru Group (Paraná Basin) of southeastern Brazil was described. The Bauru Group provided an important portrait of the Brazilian Mesozoic terrestrial biota, which boasts a vertebrate fauna formed from fishes, frogs, lacertilians, crocodyliforms, dinosaurs and mammals; records of palynomorphs; and invertebrate fauna consisted of gastropods, bivalves, ostracods and conchostracans. Nevertheless, the age of these continental deposits is not precisely estimated, which prevents global correlations, and its fauna is argued to be endemic. The new specimen described is the first turtle from the Santo Anastácio Formation, and its morphological comparison with other South American forms provided a significant advancement in the understanding of the age of this unit (Late Cretaceous). This study permitted a revision of the turtle taxa of the Bauru Group. As a result, some taxa were considered synonym, including the new Santo Anastácio form. The specimen is still unnamed due to the absence of skull characters that preclude its accurate positioning within the Bauru Group skull-based taxa. In addition, the phylogenetic affinities of this taxon were analyzed into Podocnemidinura clade.

  12. Progress in faunal correlation of Late Cenozoic fluvial sequences 2000 4: the report of the IGCP 449 biostratigraphy subgroup

    NASA Astrophysics Data System (ADS)

    Schreve, D. C.; Keen, D. H.; Limondin-Lozouet, N.; Auguste, P.; Santisteban, Juan I.; Ubilla, M.; Matoshko, A.; Bridgland, D. R.; Westaway, R.

    2007-11-01

    Vertebrate and invertebrate faunal biostratigraphy is a well-tested method for establishing relative chronologies for fluviatile sequences that has proved useful in many parts of the world. The robust bones and teeth of large mammals are commonly found in fluviatile deposits, whereas small vertebrates can be readily recovered through systematic sieving of calcareous sediments, as can molluscs, the other major faunal group that has been used for biostratigraphical analysis of fluvial sequences. Because of their rapid and quantifiable rates of evolution, extinction, body mass change and dispersal during the Late Cenozoic, mammals are especially useful for ordering the fragmentary terrestrial sequence of interglacials and glacials, and proposing correlation with the global marine climatostratigraphic record. Other groups (e.g. reptiles and amphibians, ostracods) are as yet only in the initial stages of development as a dating tool, whereas some (e.g. fish, birds) still require substantial development in order to fully explore their utility. As part of IGCP 449, vertebrate and molluscan assemblages have made important contributions to datasets from a number of areas, notably northern France, central Germany, the Czech Republic and the Ukraine. Further south, mammalian assemblages have proved useful in separating discrete periods of climatic change in Iberia and Syria. At greater distances from the core area of fluvial biostratigraphical archives, significant contributions have come from South America (Uruguay River), South Africa (Vaal) and Australia (Riverine Plain and Lake Eyre drainage basin).

  13. Proxy records of Late Holocene climate events in the eastern United States: Medieval Warm Period and Little Ice Age

    NASA Astrophysics Data System (ADS)

    Willard, D. A.; Cronin, T. M.; Hayo, K. M.

    2006-12-01

    We are conducting a multiproxy, regional reconstruction of climate variability during the last two millennia including the Medieval Warm Period (MWP) and Little Ice Age (LIA) in eastern North America. Pollen, benthic foraminifers, ostracodes, and other proxies were analyzed from high-resolution sampling of continuous sedimentary records from lakes, wetlands, and estuaries in Florida, North Carolina, Chesapeake Bay, and Lake Champlain. These records document multi-decadal changes in vegetation, temperature, precipitation, and estuarine salinity across a latitudinal transect. During both the MWP and LIA, decreased precipitation altered plant community composition and distribution in the southeastern United States, and the LIA triggered threshold changes in vegetation that persisted until anthropogenic land-cover change overwhelmed the climate signature. In the mid-Atlantic region, progressively cooler and wetter late Holocene springs culminated in a cool, wet LIA; this trend correlates with observed oceanic changes. Trend analysis of the data suggest that inter-regional correlation of multi-decadal and centennial-scale Holocene climate events will be forthcoming.

  14. Ramp Creek and Harrodsburg Limestones: A shoaling-upward sequence with storm-produced features in southern Indiana, U.S.A.. Carbonate petrology seminar, Indiana University

    NASA Astrophysics Data System (ADS)

    1987-05-01

    Most previously described examples of storm-produced stratification have been reported from siliciclastic rocks. However, such features should also be common in carbonate rocks. The Mississippian (Valmeyeran) Ramp Creek and Harrodsburg Limestones, deposited on the east margin of the Illinois Basin on top of the Borden Delta, contain storm-produced features. The dolomitic, geode-bearing Ramp Creek Limestone contains muddying-upward sequences, commonly with scoured bases overlain by grainstones, packstones, wackestones, and burrowed mudstones. These sequences are similar to hummocky sequences formed by storm waves below fair-weather wave base. The middle portion of the section including the upper Ramp Creek and lower Harrodsburg Limestones contains dolomitized mud lenses of uncertain origin. They may have formed by the baffling effect of bryozoans and/or unpreserved algae. The Harrodsburg is gradational with the Ramp Creek and consists predominantly of grainstones and packstones deposited in shallower water. Low-angle cross-stratification and truncation surfaces suggest a foreshore depositional environment for the Harrodsburg. Neither formation contains any indication of supratidal deposition as has been previously suggested. Open marine conditions during deposition of both formations are indicated by the fauna which includes crinoids, bryozoans, brachiopods, corals, ostracods, echinoids, trilobites, molluscs, fish (sharks), and trace fossils.

  15. Decadal to millennial-scale solar forcing of Last Glacial Maximum climate in the Estancia Basin of central New Mexico

    NASA Astrophysics Data System (ADS)

    Menking, Kirsten M.

    2015-05-01

    Lacustrine sediments from the Estancia Basin of central New Mexico reveal decadal to millennial oscillations in the volume of Lake Estancia during Last Glacial Maximum (LGM) time. LGM sediments consist of authigenic carbonates, detrital clastics delivered to the lake in stream flow pulses, and evaporites that precipitated in mudflats exposed during lake lowstands and were subsequently blown into the lake. Variations in sediment mineralogy thus reflect changes in hydrologic balance and were quantified using Rietveld analysis of X-ray diffraction traces. Radiocarbon dates on ostracode valve calcite allowed the construction of mineralogical time series for the interval ~ 23,600 to ~ 18,300 ka, which were subjected to spectral analysis using REDFIT (Schulz and Mudelsee, 2002). Dominant periods of ~ 900, ~ 375, and ~ 265 yr are similar to cycles in Holocene 14C production reported for a variety of tree ring records, suggesting that the Lake Estancia sediments record variations in solar activity during LGM time. A prominent spectral peak with a period of ~ 88 yr appears to reflect the solar Gleissberg cycle and may help, along with the ~ 265 yr cycle, to explain an ongoing mystery about how Lake Estancia was able to undergo abrupt expansions without overflowing its drainage basin.

  16. Response of estuarine benthic communities to zinc contamination: Tests using formulated sediments

    SciTech Connect

    Watzin, M.C.; Roscigno, P.F.

    1994-12-31

    Because of historic industrial sources, zinc contamination in Mobile Bay is of widespread concern. Using formulated sediment and a newly developed field technique, the authors examined the effects of a series of concentrations of zinc on the benthic invertebrate community at two sites. A formulated sediment that matches field sediment in grain size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments dosed with zinc at concentrations from 250--5,000 mg/kg were exposed in the field on holding racks anchored on the bottom of the bay. The abundance and diversity of benthic invertebrate recruits were used as indicators of sediment quality. The authors found significant differences in both the abundances and species composition of recruits between clean controls and the zinc contaminated sediments. All taxa did not respond similarly to changing zinc concentrations, and effects on some groups were more apparent at lower concentrations. Several families of polychaete worms, harpacticoid copepods, and ostracods appeared to be most sensitive to the zinc. Under certain conditions, some taxa were attracted to zinc contaminated sediments. Taken together, the results suggest that zinc contamination can profoundly affect the nature of the benthic community recruiting into such sediments.

  17. Late Holocene marine terraces of the Cartagena region, southern Caribbean: The product of neotectonism or a former high stand in sea-level?

    NASA Astrophysics Data System (ADS)

    Ignacio Martínez, J.; Yokoyama, Yusuke; Gomez, Andres; Delgado, Adriana; Matsuzaki, Hiroyuki; Rendon, Esteban

    2010-03-01

    The detailed stratigraphic survey and paleontological study (mollusks, corals, foraminifera and ostracods) of four low-level, ˜3 m, marine terrace sections: Punta Canoas, Manzanillo del Mar, Playa de Oro, and Tierra Bomba Island, from the Cartagena region, southern Caribbean, supplemented with 22 radiocarbon dates, reveals that the northern terraces were deposited as parasequences in a clastic depositional system compared to the Tierra Bomba Island succession that was deposited in a carbonate depositional system between ˜3600 and ˜1700 cal yrs BP. Drier conditions and the southern location of the ITCZ at about 3 ka triggered stronger easterly Trades and more dynamic southwestward sediment drift fed by the Magdalena River mouth, thus promoting the formation of sand spits that ultimately isolated the Cienaga de Tesca coastal lagoon from the Caribbean Sea. Our estimates support the hypothesis that the present position of the terraces is the product of neotectonism rather than a higher 3 ka, sea-level. Upheaval of the terraces varies between ˜3.8 mmyr -1 at Punta Canoas and ˜2.2 mmyr -1 at Tierra Bomba to ˜1.5 mmyr -1 at Manzanillo del Mar and Playa de Oro terraces. Our study corroborates previous contentions on the role of mud diapirism and the dynamics of the Dique Fault as late Holocene upheaval mechanisms.

  18. Holocene sedimentation in Richardson Bay, California

    USGS Publications Warehouse

    Connor, Cathy L.

    1983-01-01

    Examination of foraminifers, diatoms, ostracodes, clay mineralogy, and sediment-size variation from 9 borehole sites along the salt-marsh margins of Richardson Bay reveals a record of gradual infilling of fine-grained estuarine sediments. Over the past 10,000 years this area was transformed from a V-shaped Pleistocene stream valley to a flat-floored arm of the San Francisco Bay estuary. A radiocarbon date obtained from a basal peat overlying nonmarine alluvial sand near the town of Mill Valley indicates that stable salt-marsh vegetation was present in the northwestern arm of Richardson Bay 4600?165 years ago and agrees within error limits with a Holocene sea-level curve developed by Atwater, Hedel, and Helley in 1977 for southern San Francisco Bay. The average sedimentation rate over the last 4600 years is estimated to be 0.2 cm/yr for the inner part of the bay. Comparison of early maps with updated versions as well as studies of marsh plant zonations in disturbed and nondisturbed areas shows that almost half of the marsh in Richardson Bay has been leveed or filled since 1899.

  19. [Trophic range of tilapia Oreochromis aureus (Perciformes: Cichlidae) in Infiernillo dam, Michoacán-Guerrero, Mexico].

    PubMed

    Jiménez-Badillo, M L; Nepita-Villanueva, M R

    2000-01-01

    The trophic spectrum of tilapia Oreochromis aureus (Steindachner 1864), was determined by stomach content analysis in 153 organisms collected during 1993 in Michoacán-Guerrero, México. The feeding status of the fish at the time of observation was evaluated by the examination of fat surrounding the gut, gastric replection and the condition coefficient. The quantitative evaluation of the food items was carried out by the combination of the following analysis: Frequency of Occurrence, Volumetric Method, Volumetric Mean Index and Relative Importance Index. Diet consisted of: detritus and vascular plant residues as a primary food; unicellular algae as secondary food; and remains of insects and fish, graminean seeds, filamentous algae, cladocerans, ostracods, rotifers and copepods as occasional food. We detected a difference in food preferences between juveniles and adults and a variation in the consumption proportions of some food items during the rainy and dry seasons. Thus, we concluded that O. aureus is an omnivorous species with preference for detritus and vascular plant remain. Feeding seems to be determined by the abundance of food items found in the habitat and adults showed a trend to eat only detritus. Feeding does not seem to be a limiting factor in the development of the tilapia in Infiernillo dam. PMID:11354955

  20. Lithology, mineralogy, and paleontology of Quaternary lake deposits in Long Valley Caldera, California

    USGS Publications Warehouse

    Fournier, R.B.

    1989-01-01

    Drill cores and cuttings from two drill holes, about 3 km apart, in Long Valley caldera, Mono County, California, were studied using x-ray diffraction and optical methods. A thick sequence of tuffs and lake sediments was encountered in LVCH-1 (1,000 ft deep) and Republic well 66-29 (6,920 ft deep), drilled in the southeast part of the Long Valley caldera. Ostracods, diatoms, and isotopic data indicate that the sediments and tuffs were deposited in a shallow caldera lake which changed in salinity over time. Conditions ranged from very saline in the older lake to fresh in the youngest. The sequence of secondary minerals from top to bottom is: clinoptilolite, mordenite, analcime, K-feldspar (and albite). In some geothermal systems, this sequence of secondary minerals is a function of temperature; however, the paleontological and isotopic data indicate that the change in secondary minerals with increasing depth is due to the older strata being deposited in a more saline environment. No mineralogical evidence of hydrothermal alteration is present, although the high lithium content of some clays and feldspars and the isotopic composition of some sulfate (gypsum) seems to require a hydrothermal source. (Lantz-PTT)

  1. The effects of a fungicide and chytrid fungus on anuran larvae in aquatic mesocosms.

    PubMed

    Hanlon, Shane M; Lynch, Kyle J; Kerby, Jacob L; Parris, Matthew J

    2015-09-01

    The amphibian disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), has been linked to significant amphibian declines over the past three decades. The most severe effects of the pathogen have been primarily observed in relatively pristine areas that are not affected by many anthropogenic factors.One hypothesis concerning improved amphibian persistence with Bd in disturbed landscapes is that contaminants may abate the effects of Bd on amphibians. Recent laboratory studies have shown that pesticides, specifically the fungicide thiophanate-methyl (TM), can kill Bd outside of hosts and clear Bd infections within hosts. Using aquatic mesocosms, we tested the hypothesis that TM (0.43 mg/L) would alter growth and development of Lithobates sphenocephalus (southern leopard frog) tadpoles and Bd-infection loads in infected individuals. We hypothesized that the scope of such alterations and infection clearing would be affected by aquatic community variables, specifically zooplankton. TM altered zooplankton diversity (reduced cladoceran and increased copepod and ostracod abundances) and caused mortality to all tadpoles in TM-exposed tanks. In TM-free tanks, Bd-exposed tadpoles in high-density treatments metamorphosed smaller than Bd-unexposed, effects that were reversed in low-density treatments. Our study demonstrates the potential adverse effects of a fungicide and Bd on tadpoles and aquatic systems. PMID:25913318

  2. Endozoochory of seeds and invertebrates by migratory waterbirds in Oklahoma, USA

    USGS Publications Warehouse

    Green, Andy J.; Frisch, Dagmar; Michot, Thomas C.; Allain, Larry K.; Barrow, Wylie C.

    2013-01-01

    Given their abundance and migratory behavior, waterbirds have major potential for dispersing plants and invertebrates within North America, yet their role as vectors remains poorly understood. We investigated the numbers and types of invertebrates and seeds within freshly collected faecal samples (n = 22) of migratory dabbling ducks and shorebirds in November 2008 in two parts of Lake Texoma in southern Oklahoma. Killdeer Charadrius vociferus were transporting a higher number and diversity of both plants and invertebrates than the green-winged teal Anas carolinensis. Ten plant taxa and six invertebrate taxa were identified to at least genus level, although viability was not confirmed for most of these taxa. Bryozoan statoblasts (from four species not previously recorded from Oklahoma) were especially abundant in killdeer faeces, while the ostracod Candona simpsoni was detected as a live adult in torpor in the teal faeces. Cyperaceae and Juncaceae were the most abundant plant families represented and Cyperus strigosus seeds germinated after extraction from killdeer faeces. This snapshot study underlines the importance of waterbirds as vectors of passive dispersal of many organisms and the need for more research in this discipline.

  3. Hard- and soft-bottom thanatofacies from the Santa Maria di Leuca deep-water coral province, Mediterranean

    NASA Astrophysics Data System (ADS)

    Rosso, A.; Vertino, A.; Di Geronimo, I.; Sanfilippo, R.; Sciuto, F.; Di Geronimo, R.; Violanti, D.; Corselli, C.; Taviani, M.; Mastrototaro, F.; Tursi, A.

    2010-03-01

    Thanatofacies and the skeletonized components of the living facies, from which they originate have been studied from the Santa Maria di Leuca (SML) deep-water coral mound province. Faunal analysis was carried out by means of bottom sampling and underwater video observations, taking into account all benthic taxonomic groups, mostly corals, molluscs, serpulids, bryozoans, ostracods, foraminifers and barnacles, which permitted recognition of six different facies. These thanatofacies are easily distinguishable and appear to be largely corresponding and overlapping with related living facies. Some occur in mound areas, others in the intermound ones. They are as follows: the Framework-building Coral facies (FC), characterised by colonial corals, mostly Madrepora oculata; the Coral Rubble facies (CR), with proximal and distal aspects, characterised by large- to small-sized and densely to loosely packed coral fragments; the Solitary Coral facies (SC), dominated by different species depending on the availability and dimensions of hard exploitable surfaces; the Gryphus and Isidella facies (GI) in relatively coarse-grained bottoms; the Mollusc Mud facies (MM) and the Foraminifer Mud facies (FM) in comparably homogeneous silty bottoms. Facies distribution and spatial variability are discussed, in relation to hydrology and sea-floor topography. Furthermore, the SML facies are compared with living facies from the present-day Mediterranean and Pleistocene sediments of the same area. Data on bioclastic assemblages can serve for comparison with other recent aphotic, non-tropical carbonates.

  4. Palaeoenvironmental dynamics inferred from late Quaternary permafrost deposits on Kurungnakh Island, Lena Delta, Northeast Siberia, Russia

    NASA Astrophysics Data System (ADS)

    Wetterich, Sebastian; Kuzmina, Svetlana; Andreev, Andrei A.; Kienast, Frank; Meyer, Hanno; Schirrmeister, Lutz; Kuznetsova, Tatyana; Sierralta, Melanie

    2008-08-01

    Late Quaternary palaeoenvironments of the Siberian Arctic were reconstructed by combining data from several fossil bioindicators (pollen, plant macro-fossils, ostracods, insects, and mammal bones) with sedimentological and cryolithological data from permafrost deposits. The record mirrors the environmental history of Beringia and covers glacial/interglacial and stadial/interstadial climate variations with a focus on the Middle Weichselian interstadial (50-32 kyr BP). The late Pleistocene to Holocene sequence on Kurungnakh Island reflects the development of periglacial landscapes under changing sedimentation regimes which were meandering fluvial during the Early Weichselian, colluvial or proluvial on gently inclined plaines during the Middle and Late Weichselian, and thermokarst-affected during the Holocene. Palaeoecological records indicate the existence of tundra-steppe vegetation under cold continental climate conditions during the Middle Weichselian interstadial. Due to sedimentation gaps in the sequence between 32 and 17 kyr BP and 17 and 8 kyr BP, the Late Weichselian stadial is incompletely represented in the studied outcrops. Nevertheless, by several palaeoecological indications arctic tundra-steppe vegetation under extremely cold-arid conditions prevailed during the late Pleistocene. The tundra-steppe disappeared completely due to lasting paludification during the Holocene. Initially subarctic shrub tundra formed, which later retreated in course of the late Holocene cooling.

  5. Permafrost sequences on Kurungnakh Island, Lena Delta (NE Siberia, Russia) as key site of the late Quaternary environmental history of West Beringia

    NASA Astrophysics Data System (ADS)

    Wetterich, S.; Kuzmina, S.; Andreev, A. A.; Kienast, F.; Meyer, H.; Schirrmeister, L.; Kuznetsova, T.; Sierralta, M.

    2009-04-01

    Late Quaternary permafrost sequences are widely distributed in the arctic lowlands of Siberia. Because the existence of permafrost has been sensitive to climate changes during the Quaternary past, such frozen deposits are regarded as an archive of palaeoenvironmental dynamics. Late Quaternary palaeoenvironments of the Siberian Arctic were reconstructed by combining data from several fossil bioindicators (pollen, plant macro-fossils, ostracods, insects, and mammal bones) with sedimentological and cryolithological data from permafrost deposits. The late Pleistocene to Holocene sequence on Kurungnakh Island (Lena Delta, NE Siberia) reflects the environmental history of West Beringia and covers glacial/interglacial and stadial/interstadial climate variations with a focus on the Middle Weichselian interstadial (50-32 kyr BP). The record mirrors the development of periglacial landscapes under changing sedimentation regimes which were meandering fluvial during the Early Weichselian, colluvial or proluvial on gently inclined plaines during the Middle and Late Weichselian, and thermokarst-affected during the Holocene. Palaeoecological records indicate the existence of tundra-steppe vegetation under cold continental climate conditions during the Middle Weichselian interstadial. Due to sedimentation gaps in the sequence between 32 and 17 kyr BP and 17 and 8 kyr BP, the Late Weichselian stadial is incompletely represented in the studied outcrops. Nevertheless, by several palaeoecological indications arctic tundra-steppe vegetation under extremely cold-arid conditions prevailed during the late Pleistocene. The tundra-steppe disappeared completely due to lasting paludification during the Holocene. Initially subarctic shrub tundra formed, which later retreated in course of the late Holocene cooling.

  6. Contribution to the knowledge of the genus Vestalenula Rossetti & Martens, 1998 (Crustacea, Ostracoda, Darwinulidae), with the description of a new species, V. carinata n. sp., from the island of Florianópolis, Brazil.

    PubMed

    Pinto, Ricardo L; Rocha, Carlos E F; Rossetti, Giampaolo; Martens, Koen

    2013-01-01

    The genus Vestalenula is the most species rich in the putative ancient asexual ostracod Family Darwinulidae. Several new Recent species were described from various continents, mostly based on carapace shape and structure. These species were found in a variety of aquatic and (semi-) terrestrial habitats, including springs, streams, interstitial waters, leaf litter in forests and in splash zones of waterfalls. Here, we describe V carinata n. sp. from moist leaf litter, collected from the Brazilian island of Florian6polis. The species belongs to the danielopoli-lineage within the genus because of its elongated internal tooth in the left valve and elongated external keel on the right valve. It can be distinguished from all other species in this group by its size, its L/H ratio and the relative length of the keel. The relationship of this new species to the enigmatic, putative marine species Senidarwinula terraenuxforna Choe, 1988, is discussed. An identification key to species of the genus is provided. PMID:26217837

  7. Fall diet and bathymetric distribution of deepwater sculpin (Myoxocephalus thompsonii) in Lake Huron

    USGS Publications Warehouse

    O'Brien, T. P.; Roseman, E.F.; Kiley, C.S.; Schaeffer, J.S.

    2009-01-01

    Deepwater sculpin Myoxocephalus thompsonii are an important component of Great Lake's offshore benthic food webs. Recent declines in deepwater sculpin abundance and changes in bathymetric distribution may be associated with changes in the deepwater food web of Lake Huron, particularly, decreased abundance of benthic invertebrates such as Diporeia. To assess how deepwater sculpins have responded to recent changes, we examined a fifteen-year time series of spatial and temporal patterns in abundance as well as the diets of fish collected in bottom trawls during fall of 2003, 2004, and 2005. During 1992-2007, deepwater sculpin abundance declined on a lake-wide scale but the decline in abundance at shallower depths and in the southern portion of Lake Huron was more pronounced. Of the 534 fish examined for diet analysis, 97% had food in the stomach. Mysis, Diporeia, and Chironomidae were consumed frequently, while sphaerid clams, ostracods, fish eggs, and small fish were found in only low numbers. We found an inverse relationship between prevalence of Mysis and Diporeia in diets that reflected geographic and temporal trends in abundance of these invertebrates in Lake Huron. Because deepwater sculpins are an important trophic link in offshore benthic food webs, declines in population abundance and changes in distribution may cascade throughout the food web and impede fish community restoration goals.

  8. Biotically constrained palaeoenvironmental conditions of a mid-Holocene intertidal lagoon on the southern shore of the Arabian Gulf: evidence associated with a whale skeleton at Musaffah, Abu Dhabi, UAE

    NASA Astrophysics Data System (ADS)

    Stewart, J. R.; Aspinall, S.; Beech, M.; Fenberg, P.; Hellyer, P.; Larkin, N.; Lokier, S. W.; Marx, F. G.; Meyer, M.; Miller, R.; Rainbow, P. S.; Taylor, J. D.; Whittaker, J. E.; Al-Mehsin, K.; Strohmenger, C. J.

    2011-12-01

    Whale remains (a left and right mandible, scapula, humerus and fragmentary radius and ulna as well as parts of the cranium and rostrum) belonging to a probable humpback whale ( Megaptera cf. novaeangliae) were found in the well-described sabkha sequence exposed in the Musaffah Industrial Channel, Abu Dhabi, United Arab Emirates. More precisely, the whale remains were found in a series of sediments representing a range of lagoonal facies. The sediments surrounding the whale bones were age-dated at approximately 5200 14C yrs BP and are therefore interpreted to correspond to the previously documented late Flandrian sea-level peak, preceding a fall in sea-level which culminated in the supratidal sabkha overprint of the carbonates. Associated with the whale remains is an assemblage of molluscs, foraminifera and ostracods. Together with the inferred presence of sea grass and algae, these facies are interpreted to indicate a very shallow subtidal to intertidal lagoonal environment. Cirripede remains found associated with the skeleton were identified as those of the whale barnacle Coronula diadema and hence had their origins with the whale. Significantly, the low species diversity of microfossils suggests that higher salinities existed in the mid-Holocene lagoon than are present in modern counterparts. This is here inferred to be related to the onset of continental aridity in Arabia during the mid-Holocene.

  9. Deglacial climate variability in central Florida, USA

    USGS Publications Warehouse

    Willard, D.A.; Bernhardt, C.E.; Brooks, G.R.; Cronin, T. M.; Edgar, T.; Larson, R.

    2007-01-01

    Pollen and ostracode evidence from lacustrine sediments underlying modern Tampa Bay, Florida, document frequent and abrupt climatic and hydrological events superimposed on deglacial warming in the subtropics. Radiocarbon chronology on well-preserved mollusk shells and pollen residue from core MD02-2579 documents continuous sedimentation in a variety of non-marine habitats in a karst-controlled basin from 20 ka to 11.5 ka. During the last glacial maximum (LGM), much drier and cooler-than-modern conditions are indicated by pollen assemblages enriched in Chenopodiaceae and Carya, with rare Pinus (Pinus pollen increased to 20–40% during the warming of the initial deglaciation (∼ 17.2 ka), reaching near modern abundance (60–80%) during warmer, moister climates of the Bølling/Allerød interval (14.7–12.9 ka). Within the Bølling/Allerød, centennial-scale dry events corresponding to the Older Dryas and Intra-Allerød Cold Period indicate rapid vegetation response (

  10. Evidence at Lomax, Illinois, for Mid-Wisconsin (˜40,000 yr B.P.) Position of the Des Moines Lobe and for Diversion of the Mississippi River by the Lake Michigan Lobe (20,350 yr B.P.)

    NASA Astrophysics Data System (ADS)

    Curry, B. Brandon

    1998-09-01

    An abrupt change in environment from a wetland to a deeper slackwater lake at 20,345 ± 85 yr B.P. occurred in a second-order valley tributary to the Mississippi River near Lomax, Illinois. The age of this shift is associated with the overflow of glacial Lake Milan and diversion of the Mississippi River from the Princeton Valley (Rock Island to Peoria) to its present course (Rock Island to St. Louis). The diversion occurred due to blockage of the Princeton Valley segment of the ancient Mississippi River by the Lake Michigan Lobe, impoundment of glacial Lake Milan, and eventual overflow of the lake southwest of Rock Island across a former drainage divide near Andalusia, Illinois. Fossil ostracode assemblages in the slackwater sediment at Lomax indicate changes in the post-diversion, full-glacial paleohydrology and, based on multivariate analysis, hint at the area's paleoclimate. An older part of the succession at Lomax is consistent with glaciation in the upper Iowa River basin about 40,000 yr B.P. Aggradation of sediment rich in coarse silt is attributed to a response of the ancient Iowa River basin associated with deposition of the glacigenic Sheldon Creek Formation by the Des Moines Lobe.

  11. Biogeography of Abyssocythere and Dutoitella (Ostracoda), with descriptions of three new species.

    PubMed

    Brandão, Simone N; Stuhlmann, Annalena; Vital, Helenice; Brandt, Angelika

    2016-01-01

    Ostracods have an extensive fossil record and are widely applied in palaeoenvironmental reconstructions. Here, we investigate the biogeography of two common and widespread genera, Abyssocythere and Dutoitella. Both appeared in the Cretaceous and are widely distributed in modern deep seas, but all species are restricted in distribution. The earliest record of Dutoitella is from shallow water, while the earliest Abyssocythere is from the deep sea. The Southern Ocean/Southern Atlantic seem to have been the area where both genera originated, and from which they eventually colonised other oceans. Dutoitella diversified into at least eleven species during Campanian-Eocene times, and by the end of the Eocene, the genus had spread to the Indian Ocean. This pattern continued after the establishment of the psychrosphere into the Neogene, with the development of numerous Miocene species. Abyssocythere, with 15 species, while also diversifying in the late Cretaceous South Atlantic, appears to have developed fewer species than Dutoitella. Finally, we describe three new species from the Southern Ocean (Abyssocythere bensoni sp. nov., Dutoitella karanovicae sp. nov. and Dutoitella richarddinglei  sp. nov.), re-illustrate the types of Abyssocythere squalidentata (Brady, 1880) and Dutoitella suhmi (Brady, 1880), and study the soft parts of the genus Dutoitella, which were previously undocumented. PMID:27470810

  12. Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Marzen, Rachel E.; DeNinno, Lauren H.; Cronin, Thomas M.

    2016-10-01

    Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

  13. Radiostratigraphic study of the deposits of the Maikop Group, Western Azerbaijan

    NASA Astrophysics Data System (ADS)

    Efendieva, M.; Babaev, R.; Johnson, C.; Feyzullayev, A.; Aliev, Ch.

    2012-11-01

    This work presents the results of biostratigraphic study of natural outcrops of the Maikop Group, which were first carried together with detailed radiometric studies in the Ganja oil and gas-bearing region, Western Azerbaijan. The paleontological research method included determination of the genus or species (depending on the preservation) of microfaunistic remains (foraminifera, ostracods, fish remains). The radiometric research method included measurements of the integral radioactivity in the field, the sampling, as well as laboratory radionuclide (spectral) analysis. As a result of our research, the stratigraphic control of variation in the radioactivity of rocks of the Maikop Group of the Ganja oil and gas-bearing region has been established. The radioactivity of Oligocene rocks is predominantly determined by potassium content. The radioactivity of the Miocene part of the section of the Maikop Group is determined by uranium-potassium contents. Within the Ganja oil and gas-bearing region, deposits of the Kotsakhurian regional stage, which are usually referred to "barren" formations or anoxic "fish facies", contain a significant number of species of benthic foraminiferal fauna.

  14. K-T transition in Deccan Traps of central India marks major marine Seaway across India

    NASA Astrophysics Data System (ADS)

    Keller, G.; Adatte, T.; Bajpai, S.; Mohabey, D. M.; Widdowson, M.; Khosla, A.; Sharma, R.; Khosla, S. C.; Gertsch, B.; Fleitmann, D.; Sahni, A.

    2009-05-01

    Deccan intertrappean sediments in central India are generally considered as terrestrial deposits of Maastrichtian age, but the Cretaceous-Tertiary (K-T) position is still unknown. Here we report the discovery of the K-T transition, a marine incursion and environmental changes preserved within the intertrappean sediments at Jhilmili, Chhindwara District, Madhya Pradesh. Integrative biostratigraphic, sedimentologic, mineralogic and chemostratigraphic analyses reveal the basal Danian in the intertrappean sediments between lower and upper trap basalts that regionally correspond to C29r and the C29R/C29N transition, respectively. Intertrappean deposition occurred in predominantly terrestrial semi-humid to arid environments. But a short aquatic interval of fresh water ponds and lakes followed by shallow coastal marine conditions with brackish marine ostracods and early Danian zone P1a planktic foraminifera mark this interval very close to the K-T boundary. This marine incursion marks the existence of a nearby seaway, probably extending inland from the west through the Narmada and Tapti rift valleys. The Jhilmili results thus identify the K-T boundary near the end of the main phase of Deccan eruptions and indicate that a major seaway extended at least 800 km across India.

  15. Evolution, biogeography, and systematics of Puriana: evolution and speciation in Ostracoda, III.

    USGS Publications Warehouse

    Cronin, T. M.

    1987-01-01

    Three types of geographic isolation - land barriers, deep water barriers, and climatic barriers - resulted in three distinct evolutionary responses in Neogene and Quaternary species of the epineritic ostracode genus Puriana. Through systematic, paleobiogeographic, and morphologic study of several hundred fossil and Recent populations from the eastern Pacific, western Atlantic, Gulf of Mexico, and the Caribbean, the phylogeny of the genus and the geography of speciation events were determined. Isolation of large populations by the Isthumus of Panama during the Pliocene did not lead to lineage splitting in species known to have existed before the Isthmus formed. Conversely, the establishment of small isolated populations on Caribbean islands by passive dispersal mechanisms frequently led to the evolution of new species or subspecies. Climatic changes along the southeastern United States during the Pliocene also catalyzed possible parapatric speciation as populations that immigrated to the northeastern periphery of the genus' range split to form new species. The results provide evidence that evolutionary models describing the influence of abiotic events on patterns of evolution and speciation can be tested using properly selected tectonic and climatic events and fossil groups amenable to species-level analysis. Two new species, P. bajaensis and P. paikensis, are described. -Author

  16. Trophic relationships, feeding habits and seasonal dietary changes in an intertidal rockpool fish assemblage in the Gulf of Cadiz (NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Compaire, Jesus C.; Cabrera, Remedios; Gómez-Cama, Carmen; Soriguer, Milagrosa C.

    2016-06-01

    This paper describes the use of resources and diet of nine resident fish species in the rocky intertidal zone of the Gulf of Cadiz and examines whether their populations are affected by trophic competition. A stomach content analysis of the nine species revealed that only one was herbivorous (Parablennius sanguinolentus), while the rest were mainly carnivorous (Gobius bucchichi, Gobius cobitis, Gobius paganellus, Zebrus zebrus, Salaria pavo, Lepadogaster lepadogaster, Scorpaena porcus and Tripterygion tripteronotum). The most frequently consumed prey were amphipods, isopods, polychaetes, decapods, chironomids, tanaidaceans, gastropods, copepods, cumaceans and ostracods. In most species, the occurrence of polychaetes and molluscs was higher in the cold season, whereas that of isopods, decapods, chironomids and fish increased in the warm season. In general, larger specimens consumed larger prey, with an increase in the occurrence of isopods, decapods and fish. An analysis of trophic niche breadth defined G. cobitis as generalist, G. bucchichi as opportunist and S. porcus as specialist, whereas the values obtained for the other species did not indicate a clearly defined strategy. Low diet overlap values and the segregation observed in several analyses indicated an adequate distribution of resources.

  17. Mobile epifauna on Zostera marina, and infauna of its inflorescences

    NASA Astrophysics Data System (ADS)

    Hellwig-Armonies, Monika

    1988-06-01

    The faunal colonization of the leaves and inflorescences of intertidal Zostera marina L. and of the ambient water has been studied at the Island of Sylt (North Sea). The abundance of the snail Littorina littorea L. and the isopod Jaera albifrons Leach correlates significantly with leaf surface area. This is not the case with the abundance of meiofaunal Plathelminthes, Nematoda, Copepoda, and Polychaeta. However, they increase significantly with the numbers of generative shoots in the sampled seagrass bunches. Members of these taxa inhabit the Zostera inflorescences, and average abundance increases with the degree of decay of inflorescences. This temporary microhabitat presumably offers food and shelter. Copepods and ostracods dominate in the ambient water. Planktonic calanoid copepods correlate with the amount of sampled seawater, while Ostracoda correlate with the amount of resuspended detritus suggesting that they were resuspended themselves. The study shows that some meiofaunal taxa can rapidly exploit a short-lived habitat such as the Zostera inflorescences. Juvenile polychaetes use inflorescences as a nursery.

  18. Global iridium anomaly, mass extinction, and redox change at the Devonian-Carboniferous boundary

    SciTech Connect

    Wang, K. Univ. of Calgary, Alberta ); Attrep, M. Jr.; Orth, C.J. )

    1993-12-01

    Iridium abundance anomalies have been found on a global scale in the Devonian-Carboniferous (D-C) boundary interval, which records one of the largest Phanerozoic mass-extinction events, an event that devastated many groups of living organisms, such as plants, ammonoids, trilobites, conodonts, fish, foraminiferans, brachiopods, and ostracodes. At or very close to the D-C boundary, there exists a geographically widespread black-shale interval, and Ir abundances reach anomalous maxima of 0.148 ppb (Montagne Noire, France), 0.138 ppb (Alberta, Canada) 0.140 ppb (Carnic Alps, Austria), 0.156 ppb (Guangxi, China), 0.258 ppb (Guizhou, China), and 0.250 ppb (Oklahoma). The discovery of global D-C Ir anomalies argues for an impact-extinction model. However, nonchondritic ratios of Ir to other important elements and a lack of physical evidence (shocked quartz, microtektites) do not support such a scenario. The fact that all Ir abundance maxima are at sharp redox boundaries in these sections leads us to conclude that the Ir anomalies likely resulted from a sudden change in paleo-redox conditions during deposition and/or early diagenesis. 36 refs., 2 figs., 1 tab.

  19. Short term changes in zooplankton community during the summer-autumn transition in the open NW Mediterranean Sea: species composition, abundance and diversity

    NASA Astrophysics Data System (ADS)

    Raybaud, V.; Nival, P.; Mousseau, L.; Gubanova, A.; Altukhov, D.; Khvorov, S.; Ibañez, F.; Andersen, V.

    2008-05-01

    Short term changes in zooplankton community were investigated at a fixed station in offshore waters of the Ligurian Sea (Dynaproc 2 cruise, September-October 2004). Mesozooplankton was sampled with vertical WP2 hauls (200 µm mesh-size) and large mesozooplankton, macrozooplankton and micronekton with a BIONESS multinet sampler (500 µm mesh-size). Temporal variations of total biomass, species composition and abundance of major taxa were studied. Intrusions of low salinity water masses were observed two times during the cruise. The first one, which was the most important, was associated with changes in zooplankton community composition. Among copepods, the abundance of Calocalanus, Euchaeta, Heterorhabdus, Mesocalanus, Nannocalanus, Neocalanus, Pleuromamma and also calanoid copepodites increased markedly. Among non-copepod taxa, only small ostracods abundance increased. After this low salinity event,