scholarly journals Paleobathymetry of a Silurian shelf based on brachiopod assemblages: an oxygen isotope test

2006 ◽  
Vol 43 (3) ◽  
pp. 281-293 ◽  
Author(s):  
Karem Azmy ◽  
Jan Veizer ◽  
Jisuo Jin ◽  
Paul Copper ◽  
Uwe Brand
Keyword(s):  
Water Temperature ◽  
Water Depth ◽  
Water Mass ◽  
Original Material ◽  
Benthic Assemblages ◽  
Generic Level ◽  
Lower Silurian ◽  
Oxygen Isotopic ◽  
Shell Composition ◽  
Anticosti Island

Primary δ18O signals of 97 brachiopod shells from the Lower Silurian (Llandovery) carbonate succession of Anticosti Island were used to test the hypothesis of water-depth and water-temperature gradient for the Silurian onshore–offshore benthic assemblages (BA1–BA5). The analyzed shells were from the Pentamerus palaformis, Pentamerus oblongus, Stricklandia planirostrata, Ehlersella davidsonii, and Triplesia anticostiensis communities, which have been interpreted to occupy different water depths. Screening of the shells, using petrographic and chemical criteria, confirmed good preservation of original material. Shells of P. palaformis, P. oblongus, E. davidsonii, and T. anticostiensis have very similar mean δ18O values (–5‰ Vienna Peedee Belemnite (VPDB)), while shells of S. planirostrata have a somewhat lighter value (–5.6‰). The δ18O values, in corroboration with taphonomic and paleoecologic data, suggest the following: (1) that the water mass of the Anticosti carbonate shelf was warm and well mixed vertically during the Early Silurian; (2) that the pentamerid brachiopod paleocommunities that lived at ~20–90 m of water-depth show little δ18O differentiation in their shell composition; and (3) that the Pentamerus,Stricklandia, and Triplesia communities need to be investigated at the species level, as both taphonomic and oxygen isotopic data indicate that the Stricklandia planirostrata Community most likely lived in a notably warmer, shallower water than the Pentamerus palaformis Community and that Triplesia anticostiensis (BA5) lived at water temperature comparable to that of the Pentamerus habitat (BA3). This may suggest either that, at the generic level, the Pentamerus, Stricklandia, and Triplesia (Clorinda equivalent) communities may have had substantial overlap in their spatial distribution in the BA3–BA4 paleobathymetric settings or that the isotope signals are too faint to record water depth differences on a tropical shelf.

Environmental control on temporal and spatial differentiation of Early Silurian pentameride brachiopod communities, Anticosti Island, eastern CanadaThis article is one of a selection of papers published in this Special Issue on the theme The dynamic reef and shelly communities of the Paleozoic. This Special is in honour of our colleague and friend Paul Copper.

2008 ◽  
Vol 45 (2) ◽  
pp. 159-187 ◽  
Author(s):  
Jisuo Jin
Keyword(s):  
Water Depth ◽  
Environmental Control ◽  
Spatial Differentiation ◽  
Eastern Canada ◽  
Generic Level ◽  
Β Diversity ◽  
Brachiopod Fauna ◽  
Anticosti Island ◽  
High Degree ◽  
Depth Water

The Early Silurian carbonate succession of Anticosti Island, eastern Canada, contains a rich and diverse pentameride brachiopod fauna. Multivariate analyses of 91 samples (total 17 230 specimens) confirm a high degree of temporal segregation but only moderate spatial differentiation of the Virgiana , Pentamerus , Stricklandia , Ehlersella , Microcardinalia , and Clorinda communities. Most pentameride communities show a wider range of water depth than previously believed. The V. barrandei Community occupied a substrate setting from lower BA2 to upper BA3, whereas the V. mayvillensis Community lived mainly in BA4. The P. oblongus Community preferred a BA3 setting, comparable to the classic Pentamerus Community, but the P. palaformis Community was predominantly BA4. The stricklandiid communities have a high β diversity, dominated by various species of Stricklandia, Ehlersella, Microcardinalia, and Kulumbella, and occurred most commonly in BA4, but could extend to BA3 environments. The Clorinda Community of Anticosti Island preferred deep and quiet water settings, comparable to its widely accepted BA5 assignment elsewhere. At the generic level, the Virgiana, Pentamerus, and the stricklandiid communities have a largely overlapping BA range, but a clear stratigraphical separation. Thus, their temporal alternations were not likely controlled by water depth, water turbulence, or substrate conditions, but by fluctuating ocean water temperature, as suggested by chemostratigraphical and paleobiogeographical evidence.

scholarly journals Life histories and distribution of ostracods with depth in western Lake Geneva (Petit-Lac), Switzerland: a reconnaissance study

Crustaceana ◽  
2014 ◽  
Vol 87 (8-9) ◽  
pp. 1095-1123 ◽  
Author(s):  
Laurent Decrouy ◽  
Torsten W. Vennemann
Keyword(s):  
Life History ◽  
Water Temperature ◽  
Water Depth ◽  
Organic Matter Content ◽  
Environmental Parameters ◽  
Late Winter ◽  
Lake Geneva ◽  
Monthly Basis ◽  
Sampling Campaign ◽  
Western Lake

Because environmental conditions within a given basin are different for each season and at different water depth, knowledge of the life history and depth distribution of target species is important for environmental and palaeoenvironmental interpretations based on ostracod species assemblages and/or the geochemical compositions of their valves. In order to determine the distribution of species with depth as well as the life history of species from Lake Geneva, a one-year sampling campaign of living ostracods was conducted at five sites (2, 5, 13, 33 and 70 m water depth) on a monthly basis in the Petit-Lac (western basin of Lake Geneva, Switzerland). Based on the results, the different species can be classified into three groups. Littoral taxa are found at 2 and 5 m water depth and include, in decreasing numbers of individuals,Cypridopsis vidua(O. F. Müller, 1776),Pseudocandona compressa(Koch, 1838),Limnocythere inopinata(Baird, 1843),Herpetocypris reptans(Baird, 1835),Potamocypris smaragdina(Vávra, 1891),Potamocypris similis(G. W. Müller, 1912),Plesiocypridopsis newtoni(Brady & Robertson, 1870),Prionocypris zenkeri(Chyzer & Toth, 1858) andIlyocyprissp. Brady & Norman, 1889. Sublittoral species are found in a majority at 13 m water depth and to a lesser extend at 33 m water depth and include, in decreasing numbers of individuals,Fabaeformiscandona caudata(Kaufmann, 1900),Limnocytherina sanctipatricii,Candona candida(O. F. Müller, 1776) andIsocypris beauchampi(Paris, 1920). Profundal species are found equally at 13, 33 and 70 m water depth and includes, in decreasing numbers of individuals,Cytherissa lacustris(Sars, 1863),Candona neglectaSars, 1887 andCypria lacustrisLilljeborg, 1890. The occurrence ofLimnocytherina sanctipatricii(Brady & Robertson, 1869) is restricted from late winter to late spring when temperatures are low, whileC. vidua,L. inopinata,P. smaragdina,P. similis,P. newtoniandIlyocyprissp. occur predominantly from spring to early autumn when temperatures are high. Individuals ofC. neglecta,C. candida,F. caudata,P. compressa,C. lacustris,H. reptansandCp. lacustrisoccur throughout the year with juveniles and adults occurring during the same period (C. neglectaat 70 m,C. lacustrisat 13, 33 and 70 m, andH. reptansat 2, 5 and 13 m water depth) or with juveniles occurring during a different period of the year than adults (C. neglectaat 13 and 33 m andC. candida,F. caudataandP. compressaat their respective depth of occurrence). Among the environmental parameters investigated, an estimate of the relationship between ostracod autoecology and environmental parameters suggests that in the Petit-Lac: (i) water temperature and substrate characteristics are important factors controlling the distribution of species with depth, (ii) water temperature is also important for determining the timing of species development and, hence, its specific life history, and (iii) water oxygen and sedimentary organic matter content is less important compared to the other environmental parameter monitored.

scholarly journals New rhenopyrgid edrioasteroids (Echinodermata) and their implications for taxonomy, functional morphology, and paleoecology

2019 ◽  
Vol 94 (1) ◽  
pp. 115-130
Author(s):  
Timothy A. M. Ewin ◽  
Markus Martin ◽  
Phillip Isotalo ◽  
Samuel Zamora
Keyword(s):  
Functional Morphology ◽  
Morphological Variability ◽  
Structural Diversity ◽  
Lower Paleozoic ◽  
Lower Silurian ◽  
Oral Plate ◽  
Single Compound ◽  
Oral Surface ◽  
Anticosti Island ◽  
High Degree

AbstractRhenopyrgids are rare, turreted edrioasterid edrioasteroids from the lower Paleozoic with a distinctive and apparently conservative morphology. However, new, well-preserved rhenopyrgid edrioasteroid material from Canada, along with a review of described taxa, has revealed broader structural diversity in the oral surface and enabled a re-evaluation of rhenopyrgid functional morphology and paleoecology.The floor plates in Rhenopyrgus viviani n. sp., R. coronaeformis Rievers, 1961 and, R. flos Klug et al., 2008 are well fused to each other and the interradial oral plate and lack obvious sutures, thereby forming a single compound interradial plate. This differs from other rhenopyrgids where sutures are more apparent. Such fused oral surface construction is only otherwise seen in some derived edrioblastoids and in the cyathocystids, suggesting homoplasy.Our analysis further suggests that the suboral constriction could contract but the flexible pyrgate zone could not. Thus, specimens apparently lacking a sub-oral constriction should not necessarily be placed in separate genera within the Rhenopyrgidae. It also supports rhenopyrgids as epifaunal mud-stickers with only the bulbous, textured, entire holdfasts (coriaceous sacs) anchored within the substrate rather than as burrow dwellers or encrusters.Rhenopyrgus viviani n. sp. is described from the Telychian (lower Silurian) Jupiter Formation of Anticosti Island, Québec, Canada and is differentiated by a high degree of morphological variability of pedunculate plates, broader oral plates, and narrower distal ambulacral zones. Specimens lacking or with obscured diagnostic plates from the Ordovician of Montagne Noire, France, and the Ordovician and Silurian of Girvan, Scotland are also described.UUID: http://zoobank.org/7f81d67f-4155-4719-8a45-b278ad70739d

scholarly journals Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic

2006 ◽  
Vol 54 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Karen B. Costa ◽  
Felipe A. L. Toledo ◽  
Maria A.G. Pivel ◽  
Cândido A.V. Moura ◽  
Farid Chemale Jr.
Keyword(s):  
Isotopic Composition ◽  
Water Temperature ◽  
Benthic Foraminifera ◽  
Small Difference ◽  
Oxygen Isotopic Composition ◽  
South Atlantic ◽  
Ambient Seawater ◽  
Oxygen Isotopic ◽  
Isotope Equilibrium ◽  
Equilibrium Oxygen

In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerina and Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (delta18O). Based on a new relationship between delta18O and salinity for the mid-latitude western South Atlantic, we estimated the isotopic composition of equilibrium calcite (delta18Oeq) using two different equations: (1) O'Neil et al. (1969), modified by McCorkle et al. (1997) and (2) Kim & O'Neil (1997). When using (1), the small difference between delta18Oeq and delta18O of Uvigerina suggests that this genus precipitates its shell close to equilibrium with ambient seawater. The delta18O Cibicidoides data are 0.82 ‰ lower than the predicted (equilibrium) oxygen isotopic composition. Conversely, using (2) the Cibicidoides delta18O data show excellent agreement with the oxygen isotopic composition predicted from delta18O and water temperature while Uvigerina delta18O data are 0.69 ‰ higher than predicted oxygen isotope equilibrium values. Based on the evidences presented here and on the results from previous studies we suggest using the genus Cibicidoides and applying Kim & O'Neil's (1997) equation for down-core paleotemperature investigations. In the absence of enough Cibicidoides specimens we suggest using Uvigerina delta18O data and applying a correction factor of -0.69 ‰.

Spatial and Temporal Variability of Water Temperature during early Stage of Kelp Culture in Sanggou Bay, China

2014 ◽  
Vol 955-959 ◽  
pp. 1151-1154
Author(s):  
Xu Dong Qiao ◽  
Da Ji Huang ◽  
Ding Yong Zeng ◽  
Zeng Jie Jiang ◽  
Jian Guang Fang
Keyword(s):  
Water Temperature ◽  
Water Depth ◽  
Temporal Variability ◽  
Early Stage ◽  
Moving Average ◽  
Spatial And Temporal Variability ◽  
Synoptic Scale ◽  
Temperature Variations ◽  
Sanggou Bay ◽  
Filter Water

The spatial-temporal variability of water temperature in autumn during the early stage of kelp culture in Sanggou Bay was studied based on moored measurements. The vertical profiles of temperature demonstrated that the water columns were well mixed. By using moving average filter, water temperature variations were decomposed to the trend (>12d), synoptic-scale (5~12d) component, and tidal-scale (<25h) component. Temperature variations were dominated by the trend which dropped gradually during the observation. The temperature decline rates, which were affected by water depth, varied from 0.16 °C/d to 0.24 °C/d. Synoptic and tidal cycles contributed to the temporal oscillations of temperature. The synoptic-scale components were also modulated by water depth. The ranges of tidal-scale component were higher at the bay mouth than those in the inner bay. Water temperature during the early stage of kelp culture was basically within the optimum ranges for kelp and bivalves.

scholarly journals Physico-chemical properties of water of Ramshagar dighi, the largest man made historical reservoir in northern Bangladesh

2018 ◽  
Vol 23 ◽  
pp. 29-37
Author(s):  
Ashaduzzaman ◽  
MJ Hossain ◽  
S Akther
Keyword(s):  
Carbon Dioxide ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Air Temperature ◽  
Water Depth ◽  
Chemical Properties ◽  
Current Status ◽  
Chemical Parameters ◽  
Monthly Average ◽  
Physico Chemical

Ramshagar dighi is a larger historical man made reservoir (Dighi, Bengali meaning) situated at Tajpur village in Dinajpur, Bangladesh. This study was aimed to estimate current status of physico-chemical variables of water of Ramshagar dighi at Dinajpur District, Bangladesh. Monthly average changes in physico-chemical parameters such as water temperature, total dissolved oxygen, air temperature, humidity, rainfall, water depth and pH of water were analyzed for the period of 11 months from May 2011 to March 2012. The average air temperature (°C) at the study area of Ramshagar dighi at Dinajpur District was determined as 24.97 ± 4.92. Our present study showed that physico-chemical properties of water in Ramshagar dighi were monthly average of water temperature (°C) as 24.68 ± 4.77, air temperature (°C) 24.97 ± 4.92, humidity as 82.075 ± 4.14, rainfall as 1534.5 mm, water depth as 9.10 m ± 1.286, pH as7.67± 0.48 and carbon dioxide as 0.85 ± 0.92 as well as dissolved oxygen as 4.65 ± 0.62 respectively during the period of May 2011 to March 2012. Therefore, present study was conducted to assess physico-chemical properties of water of Ramshagar dighi, Dinajpur, Bangladesh.J. bio-sci. 23: 29-37, 2015

scholarly journals A modern snapshot of the isotopic composition of lacustrine biogenic carbonates – Records of seasonal water temperature variability

2021 ◽  
Author(s):  
Inga Labuhn ◽  
Franziska Tell ◽  
Ulrich von Grafenstein ◽  
Dan Hammarlund ◽  
Henning Kuhnert ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Temperature ◽  
Residence Time ◽  
Water Depth ◽  
Lake Water ◽  
The Other ◽  
Carbonate Precipitation ◽  
Water Residence Time ◽  
Oxygen Isotope Fractionation ◽  
The Mean

Abstract. Carbonate shells and encrustations from lacustrine organisms provide proxy records of past environmental and climatic changes. The carbon isotopic composition (δ13C) of such carbonates depends on the δ13C of dissolved inorganic carbon (DIC). Their oxygen isotopic composition (δ18O) is controlled by the δ18O of the lake water and on water temperature during carbonate precipitation. Lake water δ18O, in turn, reflects the δ18O of precipitation in the catchment, water residence time and mixing, and evaporation. A paleoclimate interpretation of carbonate isotope records requires a site-specific calibration based on an understanding of these local conditions. For this study, samples of different carbonate components and water were collected in the littoral zone of Lake Locknesjön, central Sweden (62.99° N, 14.85° E, 328 m a.s.l.) along a water depth gradient from 1 to 8 m. Samples from living organisms and sub-recent samples in surface sediments were taken from the calcifying alga Chara hispida, mollusks from the genus Pisidium, and adult and juvenile instars of two ostracod species, Candona candida and Candona neglecta. Neither the isotopic composition of carbonates nor the δ18O of water vary significantly with water depth, indicating a well-mixed epilimnion. The mean δ13C of Chara hispida encrustations is 4 ‰ higher than the other carbonates. This is due to fractionation related to photosynthesis, which preferentially incorporates 12C in the organic matter and increases the δ13C of the encrustations. A small effect of photosynthetic 13C enrichment in DIC is seen in contemporaneously formed valves of juvenile ostracods. The largest differences in the mean carbonate δ18O between species are caused by vital offsets, i.e. the species-specific deviations from the δ18O of inorganic carbonate which would have been precipitated in isotopic equilibrium with the water. After subtraction of these offsets, the remaining differences in the mean carbonate δ18O between species can mainly be attributed to seasonal water temperature changes. The lowest δ18O values are observed in Chara hispida encrustations, which form during the summer months when photosynthesis is most intense. Adult ostracods, which calcify their valves during the cold season, display the highest δ18O values. This is because an increase in water temperature leads to a decrease in fractionation between carbonate and water, and therefore to a decrease in carbonate δ18O. At the same time, an increase in air temperature leads to an increase in the δ18O of lake water through its effect on precipitation δ18O and on evaporation from the lake, and consequently to an increase in carbonate δ18O, opposite to the effect of increasing water temperature on oxygen-isotope fractionation. However, the seasonal and inter-annual variability in lake water δ18O is small (~0.5 ‰) due to the long water residence time of the lake. Seasonal changes in the temperature-dependent fractionation are therefore the dominant cause of carbonate δ18O differences between species when vital offsets are corrected. Temperature reconstructions based on paleotemperature equations for equilibrium carbonate precipitation using the mean δ18O of each species and the mean δ18O of lake water are well in agreement with the observed seasonal water temperature range. The high carbonate δ18O variability of samples within a species, on the other hand, leads to a large scatter in the reconstructed temperatures based on individual samples. This implies that care must be taken to obtain a representative sample size for paleotemperature reconstructions.

scholarly journals Early Silurian brachiopods (Rhynchonellata) from the Sælabonn Formation of the Ringerike district, Norway

2006 ◽  
Vol 53 ◽  
pp. 111-126
Author(s):  
Thomsen E. ◽  
Jin J. ◽  
Harper, D.A. T.
Keyword(s):  
Early Evolution ◽  
Eastern Canada ◽  
Additional Information ◽  
Lower Silurian ◽  
Anticosti Island

A revision of Kiær’s index fossils of "Etage" 6 in the Ringerike district of Norway reveals the presence of four species: Rostricellula wadti sp. nov., Platytrochalos ringerikensis sp. nov., Platytrochalos rabbei sp. nov., and Zygospiraella duboisi. Rostricellula is a common Ordovician rhynchonellide brachiopod and is known to occur in the Lower Silurian as a holdover taxon in only a few localities worldwide. Previously, Platytrochalos was known only from the Lower Silurian (Llandoverian) rocks of Anticosti Island, eastern Canada. The occurrence of this rare genus in the Ringerike district provides additional information for the early evolution and palaeogeography of the taxonomically enigmatic family Leptocoeliidae. Zygospiraella is regarded as an index genus for the Rhuddanian, and the presence of Z. duboisi provides a useful biostratigraphic control on the age of the Sælabonn Formation.

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