New lower Callovian ostracodes from the Kursk Region

Lower Callovian deposits (subpatruus and koenigi ammonite zones) in the Mikhailovskii Mine section (Central Russia, Kursk Region) yielded 13 ostracode species (two of them are new) belonging to ten genera. This ostracode assemblage corresponds to ostracode beds with Praeschuleridea wartae-Pleurocythere kurskensis. The stratigraphic range of these beds corresponds to three ammonite biohorizons: Chamoussetia crobyloides, Kepplerites gowerianus gowerianus, and K. indigestus. Three distinct ostracode assemblages have been defined in the section based on their taxonomy and occurrence pattern. Two new species, Pleurocythere kurskensis sp. nov. and Pseudohutsonia wienholzae sp. nov., are described.     

Paleosalinity in a brackish lake during the Holocene based on stable oxygen and carbon isotopes of shell carbonate in Nakaumi Lagoon, southwest Japan

Based on the relationship between salinity and δ¹⁸O and δ¹³C of modern shells in the Lake Nakaumi-Shinji lagoon system (southwestern Japan), where the salinity changes regularly from ca. 1 PSU to 34 PSU, a paleosalinity record for Nakaumi Lagoon during the Holocene has been derived from bulk mollusk shell δ¹⁸O and δ¹³C data. The robust relationships between the salinity and modern shell δ¹⁸O_ar and δ¹³C_ar (aragonite) were used to calibrate the paleosalinity reconstruction. The salinity relationships are expressed by the regressions:

Salinity (PSU)=3.86 δ¹⁸O_ar(‰ VPDB)+33.9 (n=18, r=0.978)     

Structural relationships between genetically closely related O-antigens of <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Shigella</Emphasis> spp.

Gene clusters for biosynthesis of 24 of 34 basic O-antigen forms of Shigella spp. are identical or similar to those of the genetically closely related bacterium Escherichia coli. For 18 of these relatedness was confirmed chemically by elucidation of the O-antigen (O-polysaccharide) structures. In this work, structures of the six remaining O-antigens of E. coli O32, O53, O79, O105, O183 (all related to S. boydii serotypes), and O38 (related to S. dysenteriae type 8) were established using ¹H and ¹³C NMR spectroscopy. They were found to be identical to the Shigella counterparts, except for the O32- and O38-polysaccharides, which differ in the presence of O-acetyl groups. The structure of the E. coli O105-related O-polysaccharide of S. boydii type 11 proposed earlier is revised. The contents of the O-antigen gene clusters of the related strains of E. coli and Shigella spp. and different mechanisms of O-antigen diversification in these bacteria are discussed in view of the O-polysaccharide structures established. These data illustrate the value of the O-antigen chemistry and genetics for elucidation of evolutionary relationships of bacteria.     

Water sources and water-use efficiency of desert plants in different habitats in Dunhuang,NW China

To understand habitat associated differences in desert plant water-use patterns, water stable oxygen isotope composition was used to determine water source and leaf carbon isotope composition (δ ¹³C) was used to estimate long-term water-use efficiency in three typical habitats (saline land, sandy land and Gobi) in Dunhuang. The primary findings are: (1) in the three habitats, plant species used mainly deep soil water (>120 cm), except for Kalidium foliatum in the saline land, which relied primarily on 0–40 cm soil water; (2) in the saline land and Gobi habitat, Alhagi sparsifolia had the most negative foliar δ ¹³C; in the sandy land, Elaeagnus angustifolia leaf was enriched in ¹³C than the other three species in 2011, but no species differences in foliar δ ¹³C was observed among the four species in 2012; (3) common species (Tamarix ramosissima and A. sparsifolia) may alter their water sources to cope with habitat differences associated changes in soil water availability with deeper water sources were used in the Gobi habitat with lower soil water content (SWC) compared to in the saline land and sandy land; (4) we detected significant habitat differences in foliar δ ¹³C in A. sparsifolia which may have resulted from differences in SWC and soil electrical conductivity. However, no habitat differences in foliar δ ¹³C were observed in T. ramosissima, which may attribute to the strong genetic control in T. ramosissima or the ability to access stable deep soil water. Overall, the results suggest that extremely arid climate, root distribution and soil properties worked together to determine plant water uptake in Dunhuang area.     

Differences in water-use strategies along an aridity gradient between two coexisting desert shrubs (<Emphasis Type="Italic">Reaumuria soongorica</Emphasis> and <Emphasis Type="Italic">Nitraria sphaerocarpa</Emphasis>): isotopic approaches with physiological evidence

Background and aims

Understanding the responses of different plant species to changes in available water sources is critical for accurately modeling and predicting species dynamics. Our study aimed to explore whether there were differences in water-use strategies between the two coexisting shrubs (Reaumuria soongorica and Nitraria sphaerocarpa) in response to different amounts of summer precipitation.

Methods

We conducted 3 years of field observations at three sites along an aridity gradient from the middle to lower reaches of the Heihe River basin, northwestern China. Stable oxygen composition (δ¹⁸O) in plant xylem water, soil water and groundwater were analyzed concurrently with ecophysiological measurements at monthly intervals during the growing seasons.

Results

Water source for coexisting R. soongorica and N. sphaerocarpa did not differ at the sites with high precipitation, but significantly differed in more arid locations. The N. sphaerocarpa was more sensitive to summer precipitation than R. soongorica in terms of predawn water potential, stomatal conductance and foliage carbon-isotope discrimination.

Conclusions

The plants relying on groundwater maintained consistent water use strategies, but not plants that took up precipitation-derived water. We also found that the difference in water source uptake between the coexisting species was more apparent in more arid locations.

     

Inter- and intra-annual tree-ring cellulose oxygen isotope variability in response to precipitation in Southeast China

Key message

Compared with annual tree-ring cellulose δ ¹⁸ O, intra-annual cellulose δ ¹⁸ O has potential to reconstruct precipitation with higher resolution and stronger signal intensity.

Abstract

Annual tree-ring cellulose oxygen isotope values (δ¹⁸O) of Fokienia hodginsii provide a promising proxy of monsoon-season precipitation in Southeast China. Measuring intra-annual cellulose δ¹⁸O values may reveal the seasonal variability of precipitation and the associated climate influences. Here, we examine intra-annual variation of cellulose δ¹⁸O values in Fokienia hodginsii and Cryptomeria fortune from Fujian Province, Southeast China. Both species exhibited considerable intra-annual variations in cellulose δ¹⁸O (range ~6 ‰) with a consistent pattern of enriched values near the annual ring boundary and depleted values in the central portion of the ring. Seasonal patterns in the tree-ring δ¹⁸O values generally followed changes in precipitation δ¹⁸O values. Compared with annual tree-ring cellulose δ¹⁸O, intra-annual cellulose δ¹⁸O has potential to reconstruct precipitation with higher resolution and stronger signal intensity. July tree-ring cellulose δ¹⁸O is significantly correlated (r = ?0.58, p < 0.05) with July precipitation, and June–August tree-ring cellulose δ¹⁸O and annual tree-ring cellulose δ¹⁸O, respectively, explain 52 and 41 % of the actual variance of April–August precipitation. In addition, May–October cellulose δ¹⁸O values during El Niño years are higher than in La Niña years, and April to October rainfall is lower in El Niño years than in La Niña years. Combining the significant correlations between inter-annual cellulose δ¹⁸O values and sea surface temperatures in the central tropical Pacific, our results support the hypothesis that El Niño–Southern Oscillation affects tree-ring cellulose δ¹⁸O in Southeast China by modulating seasonal precipitation.

     

Global dataset for carbon and nitrogen stable isotope ratios of lotic periphyton

Carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) have been widely employed in food web analysis. In lotic environments, periphyton is a major primary producer that makes a large contribution to food web production as well as carbon and nitrogen cycling. While the δ¹³C and δ¹⁵N values have many advantages as a natural tracer, the controls over their high spatial and temporal variability in stream periphyton are not well known. Here, we present the global dataset of δ¹³C and δ¹⁵N values of lotic periphyton from 54 published and two unpublished sources, including 978 observations from 148 streams/rivers in 38 regions around the world, from arctic to tropical sites. The 54 published sources were articles recorded during the period of 1994–2016 in 25 academic journals. The two unpublished sources were from the authors’ own data. The dataset showed that δ¹³C and δ¹⁵N values of periphyton ranged from ?47.3 to ?9.3‰ and from ?5.6 to + 22.6‰, respectively. The dataset also includes physicochemical factors (altitude, coordinates, catchment area, width, depth, geology, vegetation, canopy coverage, biome, season, presence of anadromous salmon, temperature, pH, current velocity, and discharge), nutrient data (nitrate and ammonium concentrations), and algal attributes (chlorophyll a concentration, algal species compositions, and carbonates removal) in streams/rivers studied, all of which may help interpret the δ¹³C and δ¹⁵N values of periphyton. The metadata file outlines structure of all the data and with references for data sources, providing a resource for future food web studies in stream and river ecosystems.     

The ammonoid genus <Emphasis Type="Italic">Spiroceras</Emphasis> (Spiroceratidae,Ammonoidea) from the Upper Bajocian of the Northern Caucasus

Ammonites of the genus Spiroceras are described from the Upper Bajocian of the Kyafar River Basin (Karachay-Cherkessia), including macroconchs with preserved apertures and (for the first time in the entire history of the study of Middle Jurassic heteromorphs) microconchs with lateral lappets. The microconchs of S. bispinatum (Baugier et Sauzé), mainly represented by cyrtocones with one ventral row of nodes, correspond to microconchs with a gyroconic shell and a single row of nodes. Macroconchs and microconchs of S. annulatum (Deshayes), the ribs of which lack prominent nodes or spines, are found together. The assemblage also contains small-sized slightly uncoiled shells of Spiroceras aff. S. fourneti Roman et Pétouraud with widely spaced ribs and two prominent rows of large nodes, presumably macro- and microconchs. The ornamentation of this species resembles that of the monomorph Bajocia rarinoda Sturani from the upper part of the Lower Bajocian; perhaps the latter was ancestral to the Middle Jurassic heteromorph. The above species of Spiroceras, as well as S. obliquecostatum (Quenstedt), are figured.     

Morphological and geochemical variations of <Emphasis Type="Italic">Cyprideis</Emphasis> (Ostracoda) from modern waters of the northern Neotropics

The variability of modern Cyprideis salebrosa and Cyprideis americana (Ostracoda) from the northern Neotropics were investigated in order to understand site specific influences on the isotopic composition of their valves (δ¹⁸O, δ¹³C) in comparison to their host water and to connect this to morphological features of their valves (valve size, nodosity). C. salebrosa was found in a stream (Shell Creek, Florida) and a slightly brackish lake (Laguna del Rincon, Dominican Republic; salinity <0.7 psu) while C. americana occurred in a coastal lake with polyhaline waters (Parrotee Pond, Jamaica; salinity: >20 psu). Valve size and position of nodes differed between the two species. A reverse temperature dependency have been considered to influence Shell length (seasonally in Shell Creek, summer: 1076 µm; winter: 1092 µm, supposedly permanently in Laguna del Rincon, 1035 µm). But, regarding the small dataset other factors could not be excluded to influence ostracod valve size. A decline of node frequency of C. salebrosa is mainly related to an increase in salinity. Isotopic values of ostracod valves reflect the trend in stable isotopes of their host water. Variations in Cyprideis salebrosa δ¹⁸O and δ¹³C values signify differences in their host water. Offsets of ostracod valves to a theoretical calcite precipitated in their host water with an uncertain time lag (+0.015 to +2.63 ‰) needs to be clarified. This study presents a contribution to the understanding of environmental influences on modern ostracod shell characters as basis for paleontological applications.     

N<Subscript>2</Subscript>O production by denitrification in an urban river: evidence from isotopes,functional genes,and dissolved organic matter

Rivers are important sources of N₂O emissions into the atmosphere. Nevertheless, N₂O production processes in rivers are not well identified. We measured concentrations and isotopic ratios of N₂O, NH₄ ⁺, NO₂ ^?, and NO₃ ^? in surface water to identify the microbial processes of N₂O production along the Tama River in Japan. We also measured the functional gene abundance of nitrifiers and denitrifiers (amoA-bacteria, nirK, nirS, nosZ clade I, nosZ clade II) together with concentrations of dissolved organic carbon (DOC) and fluorescence intensities of protein and humic components of dissolved organic matter (DOM) to support the elucidation of N₂O production processes. The observed nitrogen (δ¹⁵N) and oxygen (δ¹⁸O) of N₂O were within the expected isotopic range of N₂O produced by nitrate reduction, indicating that N₂O was dominantly produced by denitrification. The positive significant correlation between N₂O_Net concentration and nirK gene abundance implied that nitrifiers and denitrifiers are contributors to N₂O production. Fluorescence intensities of protein and humic components of DOM and concentrations of DOC did not show significant correlations with N₂O concentrations, which suggests that DOC and abundance of DOM components do not control dissolved N₂O. Measurement of isotope ratios of N₂O and its substrates was found to be a useful tool to obtain evidence of denitrification as the main source of N₂O production along the Tama River.     

Untersuchungen zur Frühontogenie vonNautilus pompilius (Linné)

A series of initial shells ofNautilus pompilius was investigated for morphologic and isotopic evidence of the early ontogenetic development. Shell morphologic features, such as curvature of early shell, cancellate sculpture, suture and grouping of septa, as well as very early shell injuries, color banding and shell/egg dimensions, seem to indicate an interpretation of early ontogeny differing from that which is now generally accepted. The O¹⁸/O¹⁶ and C¹³/C¹² ratios in the early shell and septa of twoNautilus specimens are given. Changes in the carbon isotope content are tentatively correlated with the end of the embryonic period and with environmental changes. Variations in the oxygen isotope content are in part ascribed to migrations from warm to cooler water after a certain stage of development. The size of the body chamber of the young animals can be determined by comparison of the isotope contents in outer shell and septa. Existing ideas concerning early ontogeny ofNautilus are critically discussed.     

Shell form,growth and life span of <Emphasis Type="Italic">Astarte arctica</Emphasis> and <Emphasis Type="Italic">A. borealis</Emphasis> (Mollusca: Bivalvia) from the subtidal zone of northeastern Sakhalin

This study investigates changes in body proportions during ontogenesis of the bivalves Astarte arctica and A. borealis from the subtidal zone of northeastern Sakhalin. Marked differences in the shell form of bivalves were found. The shell of A. arctica is convex and compact, shell length and height are comparable, and shell width is more than 50% of shell height. A. borealis has a slightly elongate and flattened shell, its width is less than 50% of its height. Shell proportions can provide a reliable criterion for differentiating the species. Mollusks grow at nearly the same rate but attain different maximum sizes. Linear growth is described by Bertalanffy’s equation: L_t = 48.2[1 ? e ^{?0.4850(t ? 0.4396)}] for A. arctica and L_t = 53.1[1 ? e^{?0.4106(t ? 0.4253)}] for A. borealis. In northeastern Sakhalin, the life span of A. arctica is 7 years and of A. borealis, 8 years. By life span, the two bivalve species from Sakhalin slightly differ from their counterparts in other regions, particularly the arctic seas.     

Shell extracts of the edible mussel and oyster induce an enhancement of the catabolic pathway of human skin fibroblasts,in vitro

Mollusc shells are composed of more than 95% calcium carbonate and less than 5% organic matrix consisting mostly of proteins, glycoproteins and polysaccharides. In this study, we investigated the effects of matrix macromolecular components extracted from the shells of two edible molluscs of economic interest, i.e., the blue mussel Mytilus edulis and the Pacific oyster Crassostrea gigas. The potential biological activities of these organic molecules were analysed on human dermal fibroblasts in primary culture. Our results demonstrate that shell extracts of the two studied molluscs modulate the metabolic activities of the cells. In addition, the extracts caused a decrease of type I collagen and a concomitant increase of active MMP-1, both at the mRNA and the protein levels. Therefore, our results suggest that shell extracts from M. edulis and C. gigas contain molecules that promote the catabolic pathway of human dermal fibroblasts. This work emphasises the potential use of these shell matrices in the context of anti-fibrotic strategies, particularly against scleroderma. More generally, it stresses the usefulness to valorise bivalve shells that are coproducts of shellfish farming activity.     

<Emphasis Type="Italic">Limnobacter humi</Emphasis> sp. nov., a thiosulfate-oxidizing,heterotrophic bacterium isolated from humus soil,and emended description of the genus <Emphasis Type="Italic">Limnobacter</Emphasis> Spring <Emphasis Type="Italic">et al.</Emphasis> 2001

Three Gram-negative, strictly aerobic, chemolithoheterotrophic bacterial strains, designated UCM-30, UCM-33, and UCM-39^T, were isolated in South Korea. Based on their 16S rRNA gene sequences, the three isolated strains were found to be similar to Limnobacter thiooxidans CS-K2^T (97.41–97.68%), Limnobacter litoralis KP1-19^T (95.55–95.76%), and various genera belonging to the class Betaproteobacteria (90.34–93.34%). DNA-DNA hybridization showed 79.3–83.9% similarity between the genomic DNA of UCM-39^T, UCM-30, and UCM-33, while the sequence similarity between UCM-39^T and L. thiooxidans KACC 13837T or L. litoralis LMG 24869T was 23.7% and 18.6%, respectively. The DNA G+C content of UCM 39T was 59.7 mol%, the major ubiquinone was Q-8, and the optimal oxidation rate was observed at 10 mM thiosulfate. The major fatty acids (≥ 10%) were summed features 3 (C_16:1 ω7c and/or C_16:1 ω6c) and 8 (C_18:1 ω7c and/or C_18:1 ω6c), and C_16:0. The major polar lipids (diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol) were found in all members of genus Limnobacter. Based on phenotypic, physiological, and phylogenetic analyses, the UCM-39T strain was found to be significantly distinct to represent a novel species affiliated to the genus Limnobacter. We propose to name it Limnobacter humi sp. nov. with the type strain UCM-39^T (=KACC 18574^T =NBRC 111650^T).     

New data on the taxonomy,distribution, and ecology of the weevil genus <Emphasis Type="Italic">Otiorhynchus</Emphasis> germar (Coleoptera,Curculionidae)

The subgenus Pocusogetus Rtt. of the genus Otiorhynchus Germ. is revised. The subgenus includes O. rosti Strl., O. shapovalovi Davidian et Yunakov, O. obsulcatus Strl., O. fischtensis Rtt., and O. gusakovi sp. n. closely related to O. fischtensis (both from Mt. Fisht, the Western Caucasus). O. fischtensis is transferred from the subgenus Vicoranius Rtt., its lectotype is designated. A key to species of Pocusogetus is given. The systematic position of the subgenera Pocusogetus and Vicoranius in the genus Otiorhynchus is discussed. New data on the geographical distribution and ecology of the little-known species of the subgenera Obvoderus Rtt., Pseudoprovadilus Magnano, and Clypeorhynchus Yunakov et Arzanov are given. Some features of ecological differentiation between Otiorhynchus species in the alpine and subalpine zones of the Caucasus are discussed.     

Crustacean microcoprolites from Jurassic (Oxfordian) hydrocarbon-seep deposits of Beauvoisin,southeastern France

Decapod crustaceans are the most conspicuous predators and scavengers of modern chemosynthesis-based ecosystems at hydrothermal vents and hydrocarbon seeps; however, very little is known about decapod crustaceans at ancient seeps or vents. Some decapods, including galatheids, are known to produce highly specific, internally structured microcoprolites. Late Jurassic (Oxfordian) hydrocarbon-seep limestones from Beauvoisin (southeastern France) were found to contain such microcoprolites including Favreina fontana n. isp., F. cf. martellensis Brönnimann and Zaninetti, Palaxius salataensis Brönnimann, Cross and Zaninetti and Palaxius isp. These diverse ichnofossils indicate that crustaceans were also a part of ancient chemosynthesis-based ecosystems. This is the first report of crustacean coprolites from a deep-water environment.     

Using oxygen stable isotopes to quantify ecosystem metabolism in northern lakes

In remote regions of the world, whole lake metabolic estimates are scarce, largely because long incubations, intensive sampling and deployment of monitoring equipment are impractical. The oxygen isotope (δ¹⁸O) mass balance approach represents a simple and efficient alternative to measure whole-lake gross primary production (GPP) and respiration (R) from a single point sample, yet this option has not been extensively explored in habitats such as remote northern lakes. Here, we explored the applicability of the method using a sensitivity analysis on simulated data, showing that in large, heterotrophic (i.e., R > GPP) lakes, model outputs are sensitive to input terms for isotopic fractionation and air–water gas exchange. Despite these sensitivities, field applications of the δ¹⁸O method generated promising results that were generally consistent with parallel, free-water diel DO metabolic modelling, but greater than in vitro incubation measurements. The isotopic approach captured both wide-ranging metabolic conditions in in situ experimental mesocosms, and the seasonal trends in GPP and R in a shallow, dystrophic lake. In a clearer, deeper heterotrophic lake, the isotope approach integrated a fraction of metalimnetic metabolism missed by diel DO metabolic estimates. Overall, metalimnetic contributions to surface δ¹⁸O–DO dynamics had the greatest impact on model outputs, but with accurate information on air–water gas exchange, mixing depth, and the vertical DO and light regime of a given system, these effects can be accounted for and the isotopic approach can yield well constrained, spatio-temporally integrated rates of GPP and R. The approach is clearly suitable for use in oligo- and mesotrophic lakes, especially in remote regions where sampling is logistically difficult.     

Feeding behavior,ration and size structure of a population of the predatory gastropod <Emphasis Type="Italic">Cryptonatica janthostoma</Emphasis> in Vostok Bay,Sea of Japan

The relationships between the shell height of the predatory gastropod Cryptonatica janthostoma and the shell length of its typical prey, the bivalve Ruditapes philippinarum, and the diameter of the borehole on the prey shell resulting from a successful attack of the predator were experimentally found and assessed statistically. The shell height of C. janthostoma calculated retrospectively from the borehole diameter using the obtained relationships was 17–52 mm. The prey of C. janthostoma are burrowing bivalves, whose populations are affected by the predator to a varying degree. In populations of medium-sized mollusks (R. philippinarum, Protothaca euglypta, P. jedoensis, and others), C. janthostoma feeds on mollusks larger than 7–10 mm; in species with a shell length greater than 100 mm (Callista brevisiphonata, Saxidomus purpuratus), it eats specimens of 10–58 mm. C. janthostoma apparently has no effect on populations of small-sized mollusks (Anisocorbula venusta) and mollusks with an active avoidance response (Clinocardium californiense).     

Non-native liana, <Emphasis Type="Italic">Euonymus fortunei</Emphasis>, associated with increased soil nutrients,unique bacterial communities,and faster decomposition rate

Invasive plants have wide-ranging impacts on native systems including reducing native plant richness and altering soil chemistry, microbes, and nutrient cycling. Increasingly, these effects are found to linger long after removal of the invader. We examined how soil chemistry, bacterial communities, and litter decomposition varied with cover of Euonymus fortunei, an invasive evergreen liana, in two central Kentucky deciduous forests. In one forest, E. fortunei invaded in the late 1990s but invasion remained patchy and we paired invaded and uninvaded plots to examine the associations between E. fortunei cover and our response variables. In the second forest, E. fortunei had completely invaded the forest by 2005; areas where it had been selectively removed by 2010 were paired with an adjacent invaded plot. Where E. fortunei had patchily invaded, E. fortunei patches had up to 3.5× nitrogen, 2.7× carbon, and 1.9× more labile glomalin in soils than uninvaded plots, whereas there were no differences in soil characteristics between invaded and removal plots. In the patchily invaded forest, bacterial community composition varied among invaded and non-invaded plots, whereas bacterial communities did not vary among invaded and removal plots. Finally, E. fortunei leaf litter decomposed faster (k = 4.91 year^?1) than the native liana (k = 3.77 year^?1), Vitis vulpina; decomposition of both E. fortunei and V. vulpina was faster in invaded (k = 7.10 year^?1) than removal plots (k = 4.77 year^?1). Our findings suggest that E. fortunei invasion increases the rate of leaf litter decomposition via high-quality litter, alters the decomposition environment, and shifts in the soil biotic communities associated with a dense mat of wintercreeper. Land managers with limited resources should target the densest mats for the greatest restoration potential and remove wintercreeper patches before they establish dense mats.