Quantification of virus genes provides evidence for seed-bank populations of phycodnaviruses in Lake Ontario, Canada

PubMed Central

Short, Cindy M; Rusanova, Oksana; Short, Steven M

2011-01-01

Using quantitative PCR, the abundances of six phytoplankton viruses DNA polymerase (polB) gene fragments were estimated in water samples collected from Lake Ontario, Canada over 26 months. Four of the polB fragments were most related to marine prasinoviruses, while the other two were most closely related to cultivated chloroviruses. Two Prasinovirus-related genes reached peak abundances of >1000 copies ml−1 and were considered ‘high abundance', whereas the other two Prasinovirus-related genes peaked at abundances <1000 copies ml−1 and were considered ‘low abundance'. Of the genes related to chloroviruses, one peaked at ca 1600 copies ml−1, whereas the other reached only ca 300 copies ml−1. Despite these differences in peak abundance, the abundances of all genes monitored were lowest during the late fall, winter and early spring; during these months the high abundance genes persisted at 100–1000 copies ml−1 while the low abundance Prasinovirus- and Chlorovirus-related genes persisted at fewer than ca 100 copies ml−1. Clone libraries of psbA genes from Lake Ontario revealed numerous Chlorella-like algae and two prasinophytes demonstrating the presence of candidate hosts for all types of viruses monitored. Our results corroborate recent metagenomic analyses that suggest that aquatic virus communities are composed of only a few abundant populations and many low abundance populations. Thus, we speculate that an ecologically important characteristic of phycodnavirus communities is seed-bank populations with members that can become numerically dominant when their host abundances reach appropriate levels. PMID:21124493

Quantification of virus genes provides evidence for seed-bank populations of phycodnaviruses in Lake Ontario, Canada.

PubMed

Short, Cindy M; Rusanova, Oksana; Short, Steven M

2011-05-01

Using quantitative PCR, the abundances of six phytoplankton viruses DNA polymerase (polB) gene fragments were estimated in water samples collected from Lake Ontario, Canada over 26 months. Four of the polB fragments were most related to marine prasinoviruses, while the other two were most closely related to cultivated chloroviruses. Two Prasinovirus-related genes reached peak abundances of >1000 copies ml(-1) and were considered 'high abundance', whereas the other two Prasinovirus-related genes peaked at abundances <1000 copies ml(-1) and were considered 'low abundance'. Of the genes related to chloroviruses, one peaked at ca 1600 copies ml(-1), whereas the other reached only ca 300 copies ml(-1). Despite these differences in peak abundance, the abundances of all genes monitored were lowest during the late fall, winter and early spring; during these months the high abundance genes persisted at 100-1000 copies ml(-1) while the low abundance Prasinovirus- and Chlorovirus-related genes persisted at fewer than ca 100 copies ml(-1). Clone libraries of psbA genes from Lake Ontario revealed numerous Chlorella-like algae and two prasinophytes demonstrating the presence of candidate hosts for all types of viruses monitored. Our results corroborate recent metagenomic analyses that suggest that aquatic virus communities are composed of only a few abundant populations and many low abundance populations. Thus, we speculate that an ecologically important characteristic of phycodnavirus communities is seed-bank populations with members that can become numerically dominant when their host abundances reach appropriate levels.

Space-based measurements of elemental abundances and their relation to solar abundances

NASA Technical Reports Server (NTRS)

Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J.

1990-01-01

The Ion Composition Instrument (ICI) aboard the ISEE-3/ICE spacecraft was in the solar wind continuously from August 1978 to December 1982. The results made it possible to establish long-term average solar wind abundance values for helium, oxygen, neon, silicon, and iron. The Charge-Energy-Mass instrument aboard the CCE spacecraft of the AMPTE mission has measured the abundance of these elements in the magnetosheath and has also added carbon, nitrogen, magnesium, and sulfur to the list. There is strong evidence that these magnetosheath abundances are representative of the solar wind. Other sources of solar wind abundances are Solar Energetic Particle experiments and Apollo lunar foils. When comparing the abundances from all of these sources with photospheric abundances, it is clear that helium is depleted in the solar wind while silicon and iron are enhanced. Solar wind abundances for carbon, nitrogen, oxygen, and neon correlate well with the photospheric values. The incorporation of minor ions into the solar wind appears to depend upon both the ionization times for the elements and the Coulomb drag exerted by the outflowing proton flux.

Threshold responses of songbirds to long-term timber management on an active industrial forest

USGS Publications Warehouse

Becker, Douglas A.; Wood, Petra Bohall; Keyser, Patrick D.; Wigley, T. Bently; Dellinger, Rachel; Weakland, Cathy A.

2011-01-01

Forest managers often seek to balance economic benefits from timber harvesting with maintenance of habitat for wildlife, ecosystem function, and human uses. Most research on the relationship between avian abundance and active timber management has been short-term, lasting one to two years, creating the need to investigate long-term avian responses and to identify harvest thresholds when a small change in habitat results in a disproportionate response in relative abundance and nest success. Our objectives were to identify trends in relative abundance and nest success and to identify landscape-scale disturbance thresholds for avian species and habitat guilds in response to a variety of harvest treatments (clear-cuts, heavy and light partial harvests) over 14 years. We conducted point counts and monitored nests at an industrial forest in the central Appalachians of West Virginia during 1996–1998, 2001–2003, and 2007–2009. Early successional species increased in relative abundance across all three time periods, whereas interior-edge and forest-interior guilds peaked in relative abundance mid-study after which the forest-interior guild declined. Of 41 species with >10 detections, four (10%) declined significantly, 13 (32%) increased significantly (only three species among all periods), and 9 (22%) peaked in abundance mid-study (over the entire study period, four species had no significant change in abundance, four declined, and one increased). Based on piecewise linear models, forest-interior and interior-edge guilds’ relative abundance harvest thresholds were 28% total harvests (all harvests combined), 10% clear-cut harvests, and 18% light partial harvests, after which abundances declined. Harvest thresholds for the early successional guild were 42% total harvests, 11% clear-cut harvest, and 10% light partial harvests, and relative abundances increased after surpassing thresholds albeit at a reduced rate of increase after the clear-cut threshold. Threshold confidence intervals for individual species overlapped their guild threshold intervals 91% of the time. Even though relative abundance of most species (80%) did not decline as the area affected by timber management increased, implementing management at or below our approximate forest-interior and interior-edge harvest thresholds would reduce the number of declining species by half, maintain higher relative abundances of four species with a net decline in abundance but that peaked in abundance mid-study, and maintain higher relative abundances of ten additional species. In contrast, this management strategy also would prevent the increase in relative abundance of seven species and limit the increase in abundance of three species that increased throughout the study.

Solar coronal and photospheric abundances from solar energetic particle measurements

NASA Technical Reports Server (NTRS)

Breneman, H.; Stone, E. C.

1985-01-01

Solar energetic particle (SEP) elemental abundance data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 = or Z or = 30. The ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

Precision Measurements of Solar Energetic Particle Elemental Composition

NASA Technical Reports Server (NTRS)

Breneman, H.; Stone, E. C.

1985-01-01

Data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spaceraft were used to determined, solar energetic particle abundances or upper limits for all elements with Z 30 from a combined set of 10 solar flares during the 1977 to 1982 time period. Statistically meaningful abundances were determined for several rare elements including P, C1, K, Ti and Mn, while the precision of the mean abundances for the more abundant elements was proved. When compared to solar photospheric spectroscopic abundances, these new SEP abundances more clearly exhibit the step-function dependence on first ionization potential previously reported.

Anomalous abundances of solar energetic particles and coronal gas: Coulomb effects and First Ionization Potential (FIP) ordering

NASA Technical Reports Server (NTRS)

Mullan, D. J.

1985-01-01

The first ionization potential (FIP) ordering of elemental abundances in solar energetic particles and in the corona which can both be explained Coulomb effects is discussed. Solar energetic particles (SEP) and coronal gas have anomalous abundances relative to the photosphere. The anomalies are similar in both cases: which led to the conclusion that SEP acceleration is not selective, but merely preserves the source abundances. It is argued that SEP acceleration can be selective, because identical selectivity operates to determine the coronal abundances. The abundance anomalies are ordered by first ionization potential (FIP).

Fear or food - abundance of red fox in relation to occurrence of lynx and wolf.

PubMed

Wikenros, Camilla; Aronsson, Malin; Liberg, Olof; Jarnemo, Anders; Hansson, Jessica; Wallgren, Märtha; Sand, Håkan; Bergström, Roger

2017-08-22

Apex predators may affect mesopredators through intraguild predation and/or supply of carrion from their prey, causing a trade-off between avoidance and attractiveness. We used wildlife triangle snow-tracking data to investigate the abundance of red fox (Vulpes vulpes) in relation to lynx (Lynx lynx) and wolf (Canis lupus) occurrence as well as land composition and vole (Microtus spp.) density. Data from the Swedish wolf-monitoring system and VHF/GPS-collared wolves were used to study the effect of wolf pack size and time since wolf territory establishment on fox abundance. Bottom-up processes were more influential than top-down effects as the proportion of arable land was the key indicator of fox abundance at the landscape level. At this spatial scale, there was no effect of wolf abundance on fox abundance, whereas lynx abundance had a positive effect. In contrast, at the wolf territory level there was a negative effect of wolves on fox abundance when including detailed information of pack size and time since territory establishment, whereas there was no effect of lynx abundance. This study shows that different apex predator species may affect mesopredator abundance in different ways and that the results may be dependent on the spatiotemporal scale and resolution of the data.

The role of geography and host abundance in the distribution of parasitoids of an alien pest

PubMed Central

Nováková, Petra; Holuša, Jaroslav

2016-01-01

Chalcid wasps (Hymenoptera: Chalcidoidea) are probably the most effective and abundant parasitoids of the horse chestnut leaf miner (Cameraria ohridella), an alien pest in Europe that lacks specialized enemies. We studied how the species richness and abundance of chalcids are influenced by altitude, direction of an alien spread and host abundance of C. ohridella. We quantified the numbers and species richness of chalcid wasps and the numbers of C. ohridella that emerged from horse chestnut (Aesculus hippocastanum) leaf litter samples collected from 35 sites in the Czech Republic. Species richness of chalcids, which was considered an indicator of the possible adaptation of parasitoids to this alien host, was unrelated to C. ohridella abundance, direction of spread, or altitude. Chalcid abundance, which was considered an indicator of parasitism of the alien host, was strongly and positively related to C. ohridella abundance. Chalcid abundance was negatively related to direction of spread and positively related, although in a non-linear manner, to altitude. The relationship of chalcid abundance with direction of spread and altitude was weaker than that with C. ohridella abundance. The results provide evidence that biological control of the alien pest C. ohridella by natural enemies might develop in the future. PMID:26819849

Estimating the abundance of mouse populations of known size: promises and pitfalls of new methods

USGS Publications Warehouse

Conn, P.B.; Arthur, A.D.; Bailey, L.L.; Singleton, G.R.

2006-01-01

Knowledge of animal abundance is fundamental to many ecological studies. Frequently, researchers cannot determine true abundance, and so must estimate it using a method such as mark-recapture or distance sampling. Recent advances in abundance estimation allow one to model heterogeneity with individual covariates or mixture distributions and to derive multimodel abundance estimators that explicitly address uncertainty about which model parameterization best represents truth. Further, it is possible to borrow information on detection probability across several populations when data are sparse. While promising, these methods have not been evaluated using mark?recapture data from populations of known abundance, and thus far have largely been overlooked by ecologists. In this paper, we explored the utility of newly developed mark?recapture methods for estimating the abundance of 12 captive populations of wild house mice (Mus musculus). We found that mark?recapture methods employing individual covariates yielded satisfactory abundance estimates for most populations. In contrast, model sets with heterogeneity formulations consisting solely of mixture distributions did not perform well for several of the populations. We show through simulation that a higher number of trapping occasions would have been necessary to achieve good estimator performance in this case. Finally, we show that simultaneous analysis of data from low abundance populations can yield viable abundance estimates.

Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil.

PubMed

Filho, J A Araujo; Brito, S V; Lima, V F; Pereira, A M A; Mesquita, D O; Albuquerque, R L; Almeida, W O

2017-05-01

Ecological characteristics and environmental variation influence both host species composition and parasite abundance. Abiotic factors such as rainfall and temperature can improve parasite development and increase its reproduction rate. The comparison of these assemblages between different environments may give us a more refined analysis of how environment affects the variation of helminth parasite abundance. The aim of the present study was to evaluate how temporal variation, host size, sex and reproduction affect helminth abundance in the Tropidurus hispidus lizard in Caatinga, Restinga and Atlantic Forest environments. Overall, larger-sized lizards showed higher helminth abundance. We found a monthly variation in the helminth species abundance in all studied areas. In the Caatinga area, monoxenic and heteroxenic parasites were related to the rainy season and to the reproductive period of lizards. In Restinga, monoxenic and heteroxenic helminth species were more abundant during the driest months. In the Atlantic Forest, the rainy and host reproductive season occurred continuously throughout the year, so parasite abundance was relatively constant. Nevertheless, heteroxenic species were more abundant in this area. The present results showed that the temporal variation, body size, sex, reproductive period and habitat type influence the abundance and composition of helminth species in T. hispidus.

Successional change in the Lake Superior fish community: population trends in ciscoes, rainbow smelt, and lake trout, 1958-2008

USGS Publications Warehouse

Gorman, Owen T.

2012-01-01

The Lake Superior fish community underwent massive changes in the second half of the 20th century. Those changes are largely reflected in changes in abundance of the adults of principal prey species, the ciscoes (Coregonus spp.), the invasive rainbow smelt (Osmerus mordax), and the principal predator, lake trout (Salvelinus namaycush). To better understand changes in species abundances, a comprehensive series of gillnet and bottom trawl data collected from 1958 to 2008 were examined. In the late 1950s/early 1960s, smelt abundance was at its maximum, wild lake trout was at its minimum, and an abundance of hatchery lake trout was increasing rapidly. The bloater (Coregonus hoyi) was the prevalent cisco in the lake; abundance was more than 300% greater than the next most abundant cisco, shortjaw cisco (C. zenithicus), followed by kiyi (C. kiyi) and lake cisco (C. artedi). By the mid-1960s, abundance of hatchery lake trout was nearing maximum, smelt abundance was beginning to decline, and abundances of all ciscoes declined, but especially that of shortjaw cisco and kiyi. By the late 1970s, recovery of wild lake trout stocks was well underway and abundances of hatchery lake trout and smelt were declining and the ciscoes were reaching their nadir. During 1980–1990, the fish community underwent a dramatic shift in organization and structure. The rapid increase in abundance of wild lake trout, concurrent with a rapid decline in hatchery lake trout, signaled the impending recovery. Rainbow smelt abundance dropped precipitously and within four years, lake cisco and bloater populations rebounded on the heels of a series of strong recruitment events. Kiyi populations showed signs of recovery by 1989, and shortjaw by 2000, though well below historic maximum abundances. High abundance of adult smelt prior to 1980 appears to be the only factor linked to recruitment failure in the ciscoes. Life history traits of the cisco species were examined to better understand their different responses to conditions of low and high predator levels, i.e., late 1950s–early 1960s vs. post 1980. Bloaters are most likely to become the predominant cisco in the absence of strong predation and the least abundant under prolonged predation; smelt share this pattern. Conversely, the lake cisco and shortjaw cisco fare better when predator abundance is high. The recovery of lake trout in Lake Superior reestablished a strong top-down influence on the fish community and its present structure and organization appears to be approaching an equilibrium that reflects a more natural state. If lake trout recovery is sustained, shortjaw cisco abundance is expected to increase and join lake cisco and kiyi as dominant cisco species, and bloater and smelt will oscillate at lower abundances.

Abundance and Source Population of Suprathermal Heavy Ions in Corotating Interaction Regions

NASA Astrophysics Data System (ADS)

Jensema, R. J.; Desai, M. I.; Broiles, T. W.; Dayeh, M. A.

2015-12-01

In this study we analyze the abundances of suprathermal heavy ions in 75 Corotating Interaction Region (CIR) events between January 1st 1995 and December 31st 2008. We correlate the heavy ion abundances in these CIRs with those measured in the solar wind and suprathermal populations upstream of these events. Our analysis reveals that the CIR suprathermal heavy ion abundances vary by nearly two orders of magnitude over the solar activity cycle, with higher abundances (e.g., Fe/O) occurring during solar maximum and depleted values occurring during solar minimum. The abundances are also energy dependent, with larger abundances at higher energies, particularly during solar maximum. Following the method used by Mason et al. 2008, we correlate the CIR abundances with the corresponding solar wind and suprathermal values measured during 6-hour intervals for upstream periods spanning 10 days prior to the start of each CIR event. This correlation reveals that suprathermal heavy ions are better correlated with upstream suprathermal abundances measured at the same energy compared with the solar wind heavy ion abundances. Using the 6-hour averaging method, we also identified timeframes of maximum correlation between the CIR and the upstream suprathermal abundances, and find that the time of maximum correlation depends on the energy of the suprathermal ions. We discuss the implications of these results in terms of previous studies of CIR and suprathermal particles, and CIR seed populations and acceleration mechanisms.

Floral abundance, richness, and spatial distribution drive urban garden bee communities.

PubMed

Plascencia, M; Philpott, S M

2017-10-01

In urban landscapes, gardens provide refuges for bee diversity, but conservation potential may depend on local and landscape features. Foraging and population persistence of bee species, as well as overall pollinator community structure, may be supported by the abundance, richness, and spatial distribution of floral resources. Floral resources strongly differ in urban gardens. Using hand netting and pan traps to survey bees, we examined whether abundance, richness, and spatial distribution of floral resources, as well as ground cover and garden landscape surroundings influence bee abundance, species richness, and diversity on the central coast of California. Differences in floral abundance and spatial distribution, as well as urban cover in the landscape, predicted different bee community variables. Abundance of all bees and of honeybees (Apis mellifera) was lower in sites with more urban land cover surrounding the gardens. Honeybee abundance was higher in sites with patchy floral resources, whereas bee species richness and bee diversity was higher in sites with more clustered floral resources. Surprisingly, bee species richness and bee diversity was lower in sites with very high floral abundance, possibly due to interactions with honeybees. Other studies have documented the importance of floral abundance and landscape surroundings for bees in urban gardens, but this study is the first to document that the spatial arrangement of flowers strongly predicts bee abundance and richness. Based on these findings, it is likely that garden managers may promote bee conservation by managing for floral connectivity and abundance within these ubiquitous urban habitats.

Seasonal abundance of horse flies (Diptera: Tabanidae) from two locations in eastern Croatia.

PubMed

Krcmar, Stjepan

2005-12-01

A total of 10,539 tabanid horse flies from 22 species and five genera was collected in the Tikves forest within the Kopacki rit Nature Park in eastern Croatia. Seasonal abundance was analyzed for the six most abundant species. Tabanus maculicornis, Tabanus tergestinus, and Haematopota pluvialis reached their highest peak abundance in the fourth week of June. Atylotus loewianus and Tabanus bromius reached their highest peak of abundance in the first week of August, whereas Tabanus sudeticus reached its maximum abundance in the third week of July. Horse flies also were collected once a week on the pasture at Petrijevci from mid-May to mid-September during 1993. Paired collections were made from a Malaise trap and from a horse by using a sweep net. A total of 2,867 tabanids belonging to 26 species was collected. The number of tabanids collected on horses was much higher than the total captured with Malaise traps. On their natural host (horse), 2.6 times more tabanids were collected than in the traps. Seasonal abundance was analyzed only for the eight most abundant species. Chrysops paralellogrammus, Tabanus autumnalis, Tabanus bromius, Tabanus tergestinus, Haematopota pluvialis, and Haematopota subcylindrica all reached their highest peak of abundance in the second week of July, whereas Tabanus maculicornis reached the maximal peak of abundance in the third week of June. Seasonal meteorological variability that occurs periodically from one year to another has a significant influence on the maximal peaks of tabanid abundance.

Plant trait-species abundance relationships vary with environmental properties in subtropical forests in eastern china.

PubMed

Yan, En-Rong; Yang, Xiao-Dong; Chang, Scott X; Wang, Xi-Hua

2013-01-01

Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes) environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N) and phosphorus (P) contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA), leaf N concentration (LN), and total leaf area per twig size (TLA) were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests.

Patterns of rare and abundant marine microbial eukaryotes.

PubMed

Logares, Ramiro; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Dolan, John R; Dunthorn, Micah; Edvardsen, Bente; Gobet, Angélique; Kooistra, Wiebe H C F; Mahé, Frédéric; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Romac, Sarah; Shalchian-Tabrizi, Kamran; Simon, Nathalie; Stoeck, Thorsten; Santini, Sébastien; Siano, Raffaele; Wincker, Patrick; Zingone, Adriana; Richards, Thomas A; de Vargas, Colomban; Massana, Ramon

2014-04-14

Biological communities are normally composed of a few abundant and many rare species. This pattern is particularly prominent in microbial communities, in which most constituent taxa are usually extremely rare. Although abundant and rare subcommunities may present intrinsic characteristics that could be crucial for understanding community dynamics and ecosystem functioning, microbiologists normally do not differentiate between them. Here, we investigate abundant and rare subcommunities of marine microbial eukaryotes, a crucial group of organisms that remains among the least-explored biodiversity components of the biosphere. We surveyed surface waters of six separate coastal locations in Europe, independently considering the picoplankton, nanoplankton, and microplankton/mesoplankton organismal size fractions. Deep Illumina sequencing of the 18S rRNA indicated that the abundant regional community was mostly structured by organismal size fraction, whereas the rare regional community was mainly structured by geographic origin. However, some abundant and rare taxa presented similar biogeography, pointing to spatiotemporal structure in the rare microeukaryote biosphere. Abundant and rare subcommunities presented regular proportions across samples, indicating similar species-abundance distributions despite taxonomic compositional variation. Several taxa were abundant in one location and rare in other locations, suggesting large oscillations in abundance. The substantial amount of metabolically active lineages found in the rare biosphere suggests that this subcommunity constitutes a diversity reservoir that can respond rapidly to environmental change. We propose that marine planktonic microeukaryote assemblages incorporate dynamic and metabolically active abundant and rare subcommunities, with contrasting structuring patterns but fairly regular proportions, across space and time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of Cluster Environment on Chemical Abundances in Virgo Cluster Spirals

NASA Astrophysics Data System (ADS)

Kennicutt, R. C.; Skillman, E. D.; Shields, G. A.; Zaritsky, D.

1995-12-01

We have obtained new chemical abundance measurements of HII regions in Virgo cluster spiral galaxies, in order to test whether the cluster environment has significantly influenced the gas-phase abundances and chemical evolution of spiral disks. The sample of 9 Virgo spirals covers a narrow range of morphological type (Sbc - Sc) but shows broad ranges in HI deficiencies and radii in the cluster. This allows us to compare the Virgo sample as a whole to field spirals, using a large sample from Zaritsky, Kennicutt, & Huchra, and to test for systematic trends with HI content and location within the cluster. The Virgo spirals show a wide dispersion in mean disk abundances and abundance gradients. Strongly HI deficient spirals closest to the cluster core show anomalously high oxygen abundances (by 0.3 to 0.5 dex), while outlying spirals with normal HI content show abundances similar to those of field spirals. The most HI depleted spirals also show weaker abundance gradients on average, but the formal significance of this trend is marginal. We find a strong correlation between mean abundance and HI/optical diameter ratio that is quite distinct from the behavior seen in field galaxies. This suggests that dynamical processes associated with the cluster environment are more important than cluster membership in determining the evolution of chemical abundances and stellar populations in spiral galaxies. Simple chemical evolution models are calculated to predict the magnitude of the abundance enhancement expected if ram-pressure stripping or curtailment of infall is responsible for the gas deficiencies. The increased abundances of the spirals in the cluster core may have significant effects on their use as cosmological standard candles.

Oxygen abundances in halo stars

NASA Astrophysics Data System (ADS)

Bessell, Michael S.; Sutherland, Ralph S.; Ruan, Kui

1991-12-01

The present study determines the oxygen abundance for a sample of metal-poor G dwarfs by analysis of OH lines between 3080 and 3200 A and the permitted high-excitation far-red O I triple. The oxygen abundances determined from the low-excitation OH lines are up to 0.55 dex lower than those measured from the high-excitation O I lines. The abundances for the far-red O I triplet lines agree with those rederived from Abia and Rebolo (1989), and the abundances from the OH lines in dwarfs and giants are in agreement with the rederived O abundances of Barbuy (1988) and others from the forbidden resonance O I line. Because the chi = 0.1.7 eV OH lines are formed in the same layers as the majority of Fe, Ti, and other neutral metal lines used for abundance analyses, it is argued that the OH lines and the forbidden O I line yield the true oxygen abundances relative to the metals.

Prickly business: abundance of sea urchins on breakwaters and coral reefs in Dubai.

PubMed

Bauman, Andrew G; Dunshea, Glenn; Feary, David A; Hoey, Andrew S

2016-04-30

Echinometra mathaei is a common echinoid on tropical reefs and where abundant plays an important role in the control of algal communities. Despite high prevalence of E. mathaei on southern Persian/Arabian Gulf reefs, their abundance and distribution is poorly known. Spatial and temporal patterns in population abundance were examined at 12 sites between breakwater and natural reef habitats in Dubai (UAE) every 3 months from 2008 to 2010. Within the breakwater habitat, densities were greatest at shallow wave-exposed sites, and reduced with both decreasing wave-exposure and increasing depth. Interestingly, E. mathaei were significantly more abundant on exposed breakwaters than natural reef sites, presumably due to differences in habitat structure and benthic cover. Population abundances differed seasonally, with peak abundances during summer (July-September) and lower abundances in winter (December-February). Seasonal fluctuations are likely the result of peak annual recruitment pulses coupled with increased fish predation from summer to winter. Copyright © 2015 Elsevier Ltd. All rights reserved.

Re-examination of the relationship between marine virus and microbial cell abundances.

PubMed

Wigington, Charles H; Sonderegger, Derek; Brussaard, Corina P D; Buchan, Alison; Finke, Jan F; Fuhrman, Jed A; Lennon, Jay T; Middelboe, Mathias; Suttle, Curtis A; Stock, Charles; Wilson, William H; Wommack, K Eric; Wilhelm, Steven W; Weitz, Joshua S

2016-01-25

Marine viruses are critical drivers of ocean biogeochemistry, and their abundances vary spatiotemporally in the global oceans, with upper estimates exceeding 10(8) per ml. Over many years, a consensus has emerged that virus abundances are typically tenfold higher than microbial cell abundances. However, the true explanatory power of a linear relationship and its robustness across diverse ocean environments is unclear. Here, we compile 5,671 microbial cell and virus abundance estimates from 25 distinct marine surveys and find substantial variation in the virus-to-microbial cell ratio, in which a 10:1 model has either limited or no explanatory power. Instead, virus abundances are better described as nonlinear, power-law functions of microbial cell abundances. The fitted scaling exponents are typically less than 1, implying that the virus-to-microbial cell ratio decreases with microbial cell density, rather than remaining fixed. The observed scaling also implies that viral effect sizes derived from 'representative' abundances require substantial refinement to be extrapolated to regional or global scales.

A Large C+N+O Abundance Spread in Giant Stars of the Globular Cluster NGC 1851

NASA Astrophysics Data System (ADS)

Yong, David; Grundahl, Frank; D'Antona, Francesca; Karakas, Amanda I.; Lattanzio, John C.; Norris, John E.

2009-04-01

Abundances of C, N, and O are determined in four bright red giants that span the known abundance range for light (Na and Al) and s-process (Zr and La) elements in the globular cluster NGC 1851. The abundance sum C+N+O exhibits a range of 0.6 dex, a factor of 4, in contrast to other clusters in which no significant C+N+O spread is found. Such an abundance range offers support for the Cassisi et al. scenario in which the double subgiant branch populations are coeval but with different mixtures of C+N+O abundances. Further, the Na, Al, Zr, and La abundances are correlated with C+N+O, and therefore NGC 1851 is the first cluster to provide strong support for the scenario in which asymptotic giant branch stars are responsible for the globular cluster light element abundance variations. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

Abundance and Distribution of Microbial Cells and Viruses in an Alluvial Aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Donald; Nolan, Jason; Williams, Kenneth H.

Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Coloradomore » River near Rifle, CO. Virus abundance ranged from 8.0 × 10 4 to 1.0 × 10 6 mL -1 and exceeded cell abundance in all samples (cell abundance ranged from 5.8 × 10 4 to 6.1 × 10 5 mL -1). The virus to microbial cell ratio ranged from 1.1 to 8.1 and averaged 3.0 ± 1.6 with virus abundance most strongly correlated to cell abundance (Spearman's ρ = 0.73, p < 0.001). Both viruses and cells were positively correlated to dissolved organic carbon (DOC) with cells having a slightly stronger correlation (Spearman's ρ = 0.46, p < 0.05 and ρ = 0.54, p < 0.05; respectively). Groundwater uranium was also strongly correlated with DOC and virus and cell abundance (Spearman's ρ = 0.62, p < 0.05; ρ = 0.46, p < 0.05; and ρ = 0.50, p < 0.05; respectively). Together the data indicate that microbial cell and virus abundance are correlated to the geochemical conditions in the aquifer. As such local geochemical conditions likely control microbial host cell abundance which in turn controls viral abundance. Given the potential impacts of viral-mediated cell lysis such as liberation of labile organic matter from lysed cells and changes in microbial community structure, viral interactions with the microbiota should be considered in an effort to understand subsurface biogeochemical cycling and contaminant mobility.« less

Abundance and Distribution of Microbial Cells and Viruses in an Alluvial Aquifer

DOE PAGES

Pan, Donald; Nolan, Jason; Williams, Kenneth H.; ...

2017-07-11

Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Coloradomore » River near Rifle, CO. Virus abundance ranged from 8.0 × 10 4 to 1.0 × 10 6 mL -1 and exceeded cell abundance in all samples (cell abundance ranged from 5.8 × 10 4 to 6.1 × 10 5 mL -1). The virus to microbial cell ratio ranged from 1.1 to 8.1 and averaged 3.0 ± 1.6 with virus abundance most strongly correlated to cell abundance (Spearman's ρ = 0.73, p < 0.001). Both viruses and cells were positively correlated to dissolved organic carbon (DOC) with cells having a slightly stronger correlation (Spearman's ρ = 0.46, p < 0.05 and ρ = 0.54, p < 0.05; respectively). Groundwater uranium was also strongly correlated with DOC and virus and cell abundance (Spearman's ρ = 0.62, p < 0.05; ρ = 0.46, p < 0.05; and ρ = 0.50, p < 0.05; respectively). Together the data indicate that microbial cell and virus abundance are correlated to the geochemical conditions in the aquifer. As such local geochemical conditions likely control microbial host cell abundance which in turn controls viral abundance. Given the potential impacts of viral-mediated cell lysis such as liberation of labile organic matter from lysed cells and changes in microbial community structure, viral interactions with the microbiota should be considered in an effort to understand subsurface biogeochemical cycling and contaminant mobility.« less

Solar Coronal and photospheric abundances from solar energetic particle measurements

NASA Technical Reports Server (NTRS)

Breneman, H.; Stone, E. C.

1985-01-01

Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 Z or = 30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

Solar coronal and photospheric abundances from solar energetic particle measurements

NASA Technical Reports Server (NTRS)

Breneman, H. H.; Stone, E. C.

1985-01-01

Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with Z = 6-30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

Distribution and abundance of decapod crustacean larvae in the southeastern Bering Sea with emphasis on commercial species. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armstrong, D.A.; Incze, L.S.; Wencker, D.L.

1981-01-01

Contents include: Distribution and abundance of king crab larvae, Paralithodes camtschatica and P. platypus in the southeast Bering Sea; Distribution and abundance of the larvae of tanner crabs in the southeastern Bering Sea; Distribution and abundance of other brachyuran larvae in the southeastern Bering Sea with emphasis on Erimacrus isenbeckii; Distribution and abundance of shrimp larvae in the southeastern Bering Sea with emphasis on pandalid species; Distribution and abundance of hermit crabs (Paguridae) in the southeasternBering Sea; Possible oil impacts on decapod larbae in the southeastern Bering Sea with emphesis on the St. George Basin.

Climate and local abundance in freshwater fishes

PubMed Central

Knouft, Jason H.; Anthony, Melissa M.

2016-01-01

Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework provides little insight into the environmental factors regulating local abundance. While range-wide variation in population abundance associated with environmental conditions has been investigated in terrestrial species, the relationship between climate and local abundance in freshwater taxa across species' distributions is not well understood. We used GIS-based temperature and precipitation data to determine the relationships between climatic conditions and range-wide variation in local abundance for 19 species of North American freshwater fishes. Climate predicted a portion of the variation in local abundance among populations for 18 species. In addition, the relationship between climatic conditions and local abundance varied among species, which is expected as lineages partition the environment across geographical space. The influence of local habitat quality on species persistence is well documented; however, our results also indicate the importance of climate in regulating population sizes across a species geographical range, even in aquatic taxa. PMID:27429769

Post-entry and volcanic contaminant abundances of zinc, copper, selenium, germanium and gallium in stratospheric micrometeorites

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1995-01-01

Some fraction of Zn, Cu, Se, Ga and Ge in chondritic interplanetary dust particles (IDPs) collected in the lower stratosphere between 1981 May and 1984 June has a volcanic origin. I present a method to evaluate the extent of this unavoidable type of stratospheric contamination for individual particles. The mass-normalized abundances for Cu and Ge as a function of mass-normalized stratospheric residence time show their time-integrated stratospheric aerosol abundances. The Zn, Se and Ga abundances show a subdivision into two groups that span approximately two-year periods following the eruptions of the Mount St. Helens (1980 May) and El Chichon (1982 April) volcanoes. Elemental abundances in particles collected at the end of each two-year period indicate low, but not necessarily ambient, volcanic stratospheric abundances. Using this time-integrated baseline, I calculate the straospheric contaminant fractions in nine IDPs and show that Zn, SE and Ga abundances in chondritic IDPs derive in part from stratospheric aerosol contaminants. Post-entry elemental abundances (i.e., the amount that survived atmospheric entry heating of the IDP) show enrichments relative to the CI abundances but in a smaller number of particles than previously suggested.

EFFECTS OF HABITAT CHARACTERIZATION ON THE ABUNDANCE AND ACTIVITY OF SUBTERRANEAN TERMITES IN ARID SOUTHEASTERN NEW MEXICO

EPA Science Inventory

Amitermes wheeleri was the most abundant termite species in most of the habitats. Gnathamitermes tubiformans was the most abundant subterranean termite species in habitats dominated by creosotebush, Larrea tridentata. Subterranean termite abundance measured by numbers of termit...

Variation in abundance of Pacific Blue Mussel (Mytilus trossulus) in the Northern Gulf of Alaska, 2006-2015

NASA Astrophysics Data System (ADS)

Bodkin, James L.; Coletti, Heather A.; Ballachey, Brenda E.; Monson, Daniel H.; Esler, Daniel; Dean, Thomas A.

2018-01-01

Mussels are conspicuous and ecologically important components of nearshore marine communities around the globe. Pacific blue mussels (Mytilus trossulus) are common residents of intertidal habitats in protected waters of the North Pacific, serving as a conduit of primary production to a wide range of nearshore consumers including predatory invertebrates, sea ducks, shorebirds, sea otters, humans, and other terrestrial mammals. We monitored seven metrics of intertidal Pacific blue mussel abundance at five sites in each of three regions across the northern Gulf of Alaska: Katmai National Park and Preserve (Katmai) (2006-2015), Kenai Fjords National Park (Kenai Fjords) (2008-2015) and western Prince William Sound (WPWS) (2007-2015). Metrics included estimates of: % cover at two tide heights in randomly selected rocky intertidal habitat; and in selected mussel beds estimates of: the density of large mussels (≥ 20 mm); density of all mussels > 2 mm estimated from cores extracted from those mussel beds; bed size; and total abundance of large and all mussels, i.e. the product of density and bed size. We evaluated whether these measures of mussel abundance differed among sites or regions, whether mussel abundance varied over time, and whether temporal patterns in abundance were site specific, or synchronous at regional or Gulf-wide spatial scales. We found that, for all metrics, mussel abundance varied on a site-by-site basis. After accounting for site differences, we found similar temporal patterns in several measures of abundance (both % cover metrics, large mussel density, large mussel abundance, and mussel abundance estimated from cores), in which abundance was initially high, declined significantly over several years, and subsequently recovered. Averaged across all sites, we documented declines of 84% in large mussel abundance through 2013 with recovery to 41% of initial abundance by 2015. These findings suggest that factors operating across the northern Gulf of Alaska were affecting mussel survival and subsequently abundance. In contrast, density of primarily small mussels obtained from cores (as an index of recruitment), varied markedly by site, but did not show meaningful temporal trends. We interpret this to indicate that settlement was driven by site-specific features rather than Gulf wide factors. By extension, we hypothesize that temporal changes in mussel abundance observed was not a result of temporal variation in larval supply leading to variation in recruitment, but rather suggestive of mortality as a primary demographic factor driving mussel abundance. Our results highlight the need to better understand underlying mechanisms of change in mussels, as well as implications of that change to nearshore consumers.

Variation in abundance of Pacific Blue Mussel (Mytilus trossulus) in the Northern Gulf of Alaska, 2006–2015

USGS Publications Warehouse

Bodkin, James L.; Coletti, Heather A.; Ballachey, Brenda E.; Monson, Daniel; Esler, Daniel N.; Dean, Thomas A.

2017-01-01

Mussels are conspicuous and ecologically important components of nearshore marine communities around the globe. Pacific blue mussels (Mytilus trossulus) are common residents of intertidal habitats in protected waters of the North Pacific, serving as a conduit of primary production to a wide range of nearshore consumers including predatory invertebrates, sea ducks, shorebirds, sea otters, humans, and other terrestrial mammals. We monitored seven metrics of intertidal Pacific blue mussel abundance at five sites in each of three regions across the northern Gulf of Alaska: Katmai National Park and Preserve (Katmai) (2006–2015), Kenai Fjords National Park (Kenai Fjords) (2008–2015) and western Prince William Sound (WPWS) (2007–2015). Metrics included estimates of: % cover at two tide heights in randomly selected rocky intertidal habitat; and in selected mussel beds estimates of: the density of large mussels (≥ 20 mm); density of all mussels > 2 mm estimated from cores extracted from those mussel beds; bed size; and total abundance of large and all mussels, i.e. the product of density and bed size. We evaluated whether these measures of mussel abundance differed among sites or regions, whether mussel abundance varied over time, and whether temporal patterns in abundance were site specific, or synchronous at regional or Gulf-wide spatial scales. We found that, for all metrics, mussel abundance varied on a site-by-site basis. After accounting for site differences, we found similar temporal patterns in several measures of abundance (both % cover metrics, large mussel density, large mussel abundance, and mussel abundance estimated from cores), in which abundance was initially high, declined significantly over several years, and subsequently recovered. Averaged across all sites, we documented declines of 84% in large mussel abundance through 2013 with recovery to 41% of initial abundance by 2015. These findings suggest that factors operating across the northern Gulf of Alaska were affecting mussel survival and subsequently abundance. In contrast, density of primarily small mussels obtained from cores (as an index of recruitment), varied markedly by site, but did not show meaningful temporal trends. We interpret this to indicate that settlement was driven by site-specific features rather than Gulf wide factors. By extension, we hypothesize that temporal changes in mussel abundance observed was not a result of temporal variation in larval supply leading to variation in recruitment, but rather suggestive of mortality as a primary demographic factor driving mussel abundance. Our results highlight the need to better understand underlying mechanisms of change in mussels, as well as implications of that change to nearshore consumers.

Commonly rare and rarely common: comparing population abundance of invasive and native aquatic species.

PubMed

Hansen, Gretchen J A; Vander Zanden, M Jake; Blum, Michael J; Clayton, Murray K; Hain, Ernie F; Hauxwell, Jennifer; Izzo, Marit; Kornis, Matthew S; McIntyre, Peter B; Mikulyuk, Alison; Nilsson, Erika; Olden, Julian D; Papeş, Monica; Sharma, Sapna

2013-01-01

Invasive species are leading drivers of environmental change. Their impacts are often linked to their population size, but surprisingly little is known about how frequently they achieve high abundances. A nearly universal pattern in ecology is that species are rare in most locations and abundant in a few, generating right-skewed abundance distributions. Here, we use abundance data from over 24,000 populations of 17 invasive and 104 native aquatic species to test whether invasive species differ from native counterparts in statistical patterns of abundance across multiple sites. Invasive species on average reached significantly higher densities than native species and exhibited significantly higher variance. However, invasive and native species did not differ in terms of coefficient of variation, skewness, or kurtosis. Abundance distributions of all species were highly right skewed (skewness>0), meaning both invasive and native species occurred at low densities in most locations where they were present. The average abundance of invasive and native species was 6% and 2%, respectively, of the maximum abundance observed within a taxonomic group. The biological significance of the differences between invasive and native species depends on species-specific relationships between abundance and impact. Recognition of cross-site heterogeneity in population densities brings a new dimension to invasive species management, and may help to refine optimal prevention, containment, control, and eradication strategies.

Commonly Rare and Rarely Common: Comparing Population Abundance of Invasive and Native Aquatic Species

PubMed Central

Hansen, Gretchen J. A.; Vander Zanden, M. Jake; Blum, Michael J.; Clayton, Murray K.; Hain, Ernie F.; Hauxwell, Jennifer; Izzo, Marit; Kornis, Matthew S.; McIntyre, Peter B.; Mikulyuk, Alison; Nilsson, Erika; Olden, Julian D.; Papeş, Monica; Sharma, Sapna

2013-01-01

Invasive species are leading drivers of environmental change. Their impacts are often linked to their population size, but surprisingly little is known about how frequently they achieve high abundances. A nearly universal pattern in ecology is that species are rare in most locations and abundant in a few, generating right-skewed abundance distributions. Here, we use abundance data from over 24,000 populations of 17 invasive and 104 native aquatic species to test whether invasive species differ from native counterparts in statistical patterns of abundance across multiple sites. Invasive species on average reached significantly higher densities than native species and exhibited significantly higher variance. However, invasive and native species did not differ in terms of coefficient of variation, skewness, or kurtosis. Abundance distributions of all species were highly right skewed (skewness>0), meaning both invasive and native species occurred at low densities in most locations where they were present. The average abundance of invasive and native species was 6% and 2%, respectively, of the maximum abundance observed within a taxonomic group. The biological significance of the differences between invasive and native species depends on species-specific relationships between abundance and impact. Recognition of cross-site heterogeneity in population densities brings a new dimension to invasive species management, and may help to refine optimal prevention, containment, control, and eradication strategies. PMID:24194883

Variation of tsetse fly abundance in relation to habitat and host presence in the Maasai Steppe, Tanzania.

PubMed

Ngonyoka, Anibariki; Gwakisa, Paul S; Estes, Anna B; Nnko, Happiness J; Hudson, Peter J; Cattadori, Isabella M

2017-06-01

Human activities modify ecosystem structure and function and can also alter the vital rates of vectors and thus the risk of infection with vector-borne diseases. In the Maasai Steppe ecosystem of northern Tanzania, local communities depend on livestock and suitable pasture that is shared with wildlife, which can increase tsetse abundance and the risk of trypanosomiasis. We monitored the monthly tsetse fly abundance adjacent to Tarangire National Park in 2014-2015 using geo-referenced, baited epsilon traps. We examined the effect of habitat types and vegetation greenness (NDVI) on the relative abundance of tsetse fly species. Host availability (livestock and wildlife) was also recorded within 100×100 m of each trap site. The highest tsetse abundance was found in the ecotone between Acacia-Commiphora woodland and grassland, and the lowest in riverine woodland. Glossina swynnertoni was the most abundant species (68%) trapped throughout the entire study, while G. pallidipes was the least common (4%). Relative species abundance was negatively associated with NDVI, with greatest abundance observed in the dry season. The relationship with the abundance of wildlife and livestock was more complex, as we found positive and negative associations depending on the host and fly species. While habitat is important for tsetse distribution, hosts also play a critical role in affecting fly abundance and, potentially, trypanosomiasis risk. © 2017 The Society for Vector Ecology.

Fish and Phytoplankton Exhibit Contrasting Temporal Species Abundance Patterns in a Dynamic North Temperate Lake

PubMed Central

Hansen, Gretchen J. A.; Carey, Cayelan C.

2015-01-01

Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of “core” (common occurrence and high abundance) and “occasional” (rare occurrence and low abundance) species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions. PMID:25651399

Carbon and nitrogen abundances in metal-poor dwarfs of the solar neighborhood

NASA Technical Reports Server (NTRS)

Carbon, Duane F.; Barbuy, Beatrice; Kraft, Robert P.; Friel, Eileen D.; Suntzeff, Nicholas B.

1987-01-01

Intermediate-resolution C, N, and Fe abundance spectra for 83 subdwarfs in the lowest metallicity range (-1.5 to -3.2), obtained with the Lick Observatory 3.1-m Shane telescope, are analyzed. The effects of subgiants and binaries on the sample are examined. The relation between (B-V) and (V-K) and effective temperature is studied. C/Fe, N/Fe, and Fe/H abundances were determined using the model-atmosphere technique of spectrum synthesis. The derived abundance values are compared with data from previous investigations. It is observed that there is good correlation between the Fe/H abundance values derived from the intermediate-resolution spectra and those based on high-resolution spectra; C/Fe abundance values are constant; and there is an upturn in the C/Fe abundance values at the very lowest metallicities.

The distribution of alpha elements in Andromeda dwarf galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vargas, Luis C.; Geha, Marla C.; Tollerud, Erik J., E-mail: luis.vargas@yale.edu

We present alpha to iron abundance ratios for 226 individual red giant branch stars in nine dwarf galaxies of the Andromeda (M31) satellite system. The abundances are measured from the combined signal of Mg, Si, Ca, and Ti lines in Keck/DEIMOS medium-resolution spectra. This constitutes the first large sample of alpha abundance ratios measured in the M31 satellite system. The dwarf galaxies in our sample exhibit a variety of alpha abundance ratios, with the average values in each galaxy ranging from approximately solar ([α/Fe] ∼ + 0.0) to alpha-enhanced ([α/Fe] ∼ + 0.5). These variations do not show a correlationmore » with internal kinematics, environment, or stellar density. We confirm radial gradients in the iron abundance of two galaxies out of the five with sufficient data (NGC 185 and And II). There is only tentative evidence for an alpha abundance radial gradient in NGC 185. We homogeneously compare our results to the Milky Way classical dwarf spheroidals, finding evidence for wider variation in average alpha abundance. In the absence of chemical abundances for the M31 stellar halo, we compare to the Milky Way stellar halo. A stellar halo comprised of disrupted M31 satellites is too metal-rich and inconsistent with the Milky Way halo alpha abundance distribution even if considering only satellites with predominantly old stellar populations. The M31 satellite population provides a second system in which to study chemical abundances of dwarf galaxies and reveals a wider variety of abundance patterns than the Milky Way.« less

The Lithium Abundances of a Large Sample of Red Giants

NASA Astrophysics Data System (ADS)

Liu, Y. J.; Tan, K. F.; Wang, L.; Zhao, G.; Sato, Bun'ei; Takeda, Y.; Li, H. N.

2014-04-01

The lithium abundances for 378 G/K giants are derived with non-local thermodynamic equilibrium correction considered. Among these are 23 stars that host planetary systems. The lithium abundance is investigated, as a function of metallicity, effective temperature, and rotational velocity, as well as the impact of a giant planet on G/K giants. The results show that the lithium abundance is a function of metallicity and effective temperature. The lithium abundance has no correlation with rotational velocity at v sin i < 10 km s-1. Giants with planets present lower lithium abundance and slow rotational velocity (v sin i < 4 km s-1). Our sample includes three Li-rich G/K giants, 36 Li-normal stars, and 339 Li-depleted stars. The fraction of Li-rich stars in this sample agrees with the general rate of less than 1% in the literature, and the stars that show normal amounts of Li are supposed to possess the same abundance at the current interstellar medium. For the Li-depleted giants, Li-deficiency may have already taken place at the main sequence stage for many intermediate mass (1.5-5 M ⊙) G/K giants. Finally, we present the lithium abundance and kinematic parameters for an enlarged sample of 565 giants using a compilation of the literature, and confirm that the lithium abundance is a function of metallicity and effective temperature. With the enlarged sample, we investigate the differences between the lithium abundance in thin-/thick-disk giants, which indicate that the lithium abundance in thick-disk giants is more depleted than that in thin-disk giants.

Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes

PubMed Central

Fauteux, Lisa; Cottrell, Matthew T.; Kirchman, David L.; Borrego, Carles M.; Garcia-Chaves, Maria Carolina; del Giorgio, Paul A.

2015-01-01

There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex. PMID:25927833

Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes.

PubMed

Fauteux, Lisa; Cottrell, Matthew T; Kirchman, David L; Borrego, Carles M; Garcia-Chaves, Maria Carolina; Del Giorgio, Paul A

2015-01-01

There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex.

Plant Trait-Species Abundance Relationships Vary with Environmental Properties in Subtropical Forests in Eastern China

PubMed Central

Yan, En-Rong; Yang, Xiao-Dong; Chang, Scott X.; Wang, Xi-Hua

2013-01-01

Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes) environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N) and phosphorus (P) contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA), leaf N concentration (LN), and total leaf area per twig size (TLA) were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests. PMID:23560114

Grassland bird use of oak barrens and dry prairies in Wisconsin

USGS Publications Warehouse

Vos, Susan M.; Ribic, Christine A.

2011-01-01

Grassland bird populations have declined more than any other group of birds in North America and are of conservation concern to state and federal agencies. We determined relative abundances of grassland birds in oak barrens and dry sand prairies—native habitat types rare in the state of Wisconsin. We also investigated the association of relative abundance, patch size, and patch vegetation. Our study was conducted May–July 2000–2002 on Fort McCoy Military Installation in Monroe County, Wisconsin. Fourteen grassland bird species were found in native habitat patches. Vesper sparrow (Pooecetes gramineus), grasshopper sparrow (Ammodramus savannarum), and field sparrow (Spizella pusilla) were the most abundant grassland bird species; all are species of management concern in Wisconsin. Of the most abundant species, only grasshopper sparrow relative abundance increased as patch size increased; vesper sparrow and field sparrow relative abundances decreased as patch size increased. Though found at lower relative abundances, horned larks (Erephila alpestris), savannah sparrows (Passerculus sandwichensis), and upland sandpipers (Bartramia longicauda) were found at higher relative abundances as patch size increased. Patch vegetation was important for some species. Vesper sparrows were found at higher abundances in patches with shorter, less dense vegetation and higher woody cover, eastern meadowlark (Sturnella magna) relative abundances were higher in patches with higher proportions of grass, and dickcissel (Spiza americana) relative abundances were higher in patches with taller, denser vegetation and lower proportions of litter. Native habitats are important for grassland bird species of management concern and large patches are particularly important for some of them.

Social Insects Dominate Eastern US Temperate Hardwood Forest Macroinvertebrate Communities in Warmer Regions

PubMed Central

King, Joshua R.; Warren, Robert J.; Bradford, Mark A.

2013-01-01

Earthworms, termites, and ants are common macroinvertebrates in terrestrial environments, although for most ecosystems data on their abundance and biomass is sparse. Quantifying their areal abundance is a critical first step in understanding their functional importance. We intensively sampled dead wood, litter, and soil in eastern US temperate hardwood forests at four sites, which span much of the latitudinal range of this ecosystem, to estimate the abundance and biomass m−2 of individuals in macroinvertebrate communities. Macroinvertebrates, other than ants and termites, differed only slightly among sites in total abundance and biomass and they were similar in ordinal composition. Termites and ants were the most abundant macroinvertebrates in dead wood, and ants were the most abundant in litter and soil. Ant abundance and biomass m−2 in the southernmost site (Florida) were among the highest values recorded for ants in any ecosystem. Ant and termite biomass and abundance varied greatly across the range, from <1% of the total macroinvertebrate abundance (in the northern sites) to >95% in the southern sites. Our data reveal a pronounced shift to eusocial insect dominance with decreasing latitude in a temperate ecosystem. The extraordinarily high social insect relative abundance outside of the tropics lends support to existing data suggesting that ants, along with termites, are globally the most abundant soil macroinvertebrates, and surpass the majority of other terrestrial animal (vertebrate and invertebrate) groups in biomass m−2. Our results provide a foundation for improving our understanding of the functional role of social insects in regulating ecosystem processes in temperate forest. PMID:24116079

Abundance and distribution of Corallorhiza odontorhiza reflect variations in climate and ectomycorrhizae

Treesearch

Melissa K. McCormick; Dennis F. Whigham; John P. O' Neill; Janie J. Becker; Sarah Werner; Hanne N. Rasmussen; Thomas D. Bruns; D. Lee Taylor

2009-01-01

The abundance and reproductive activity of orchids have been linked to variations in weather conditions, but few investigators have examined the relationships between orchid flowering dynamics and the distribution and abundance of mycorrhizal fungi. We quantified the abundance of flowering individuals of Corallorhiza odontorhiza, a...

ABUNDANT OR RARE? A HYBRID APPROACH FOR DETERMINING SPECIES RELATIVE ABUNDANCE AT AN ECOREGOIONAL SCALE

EPA Science Inventory

Everyone knows what abundant and rare species are, but quantifying the concept proves elusive. As part of an EPA/USGS project to assess near-coastal species vulnerability to climate change affects, we designed a hybrid approach to determine species relative abundance at an ecoreg...

On the differences in element abundances of energetic ions from corotating events and from large solar events

NASA Technical Reports Server (NTRS)

Reames, D. V.; Richardson, I. G.; Barbier, L. M.

1991-01-01

The abundances of energetic ions accelerated from high-speed solar wind streams by shock waves formed at corotating interaction regions (CIRs) where high-speed streams overtake the lower-speed solar wind are examined. The observed element abundances appear to represent those of the high-speed solar wind, unmodified by the shock acceleration. These abundances, relative to those in the solar photosphere, are organized by the first ionization potential (FIP) of the ions in a way that is different from the FIP effect commonly used to describe differences between abundances in the solar photosphere and those in the solar corona, solar energetic particles (SEPs), and the low-speed solar wind. In contrast, the FIP effect of the ion abundances in the CIR events is characterized by a smaller amplitude of the differences between high-FIP and low-FIP ions and by elevated abundances of He, C, and S.

Integrated omics dissection of proteome dynamics during cardiac remodeling.

PubMed

Lau, Edward; Cao, Quan; Lam, Maggie P Y; Wang, Jie; Ng, Dominic C M; Bleakley, Brian J; Lee, Jessica M; Liem, David A; Wang, Ding; Hermjakob, Henning; Ping, Peipei

2018-01-09

Transcript abundance and protein abundance show modest correlation in many biological models, but how this impacts disease signature discovery in omics experiments is rarely explored. Here we report an integrated omics approach, incorporating measurements of transcript abundance, protein abundance, and protein turnover to map the landscape of proteome remodeling in a mouse model of pathological cardiac hypertrophy. Analyzing the hypertrophy signatures that are reproducibly discovered from each omics data type across six genetic strains of mice, we find that the integration of transcript abundance, protein abundance, and protein turnover data leads to 75% gain in discovered disease gene candidates. Moreover, the inclusion of protein turnover measurements allows discovery of post-transcriptional regulations across diverse pathways, and implicates distinct disease proteins not found in steady-state transcript and protein abundance data. Our results suggest that multi-omics investigations of proteome dynamics provide important insights into disease pathogenesis in vivo.

Estimating population size with correlated sampling unit estimates

Treesearch

David C. Bowden; Gary C. White; Alan B. Franklin; Joseph L. Ganey

2003-01-01

Finite population sampling theory is useful in estimating total population size (abundance) from abundance estimates of each sampled unit (quadrat). We develop estimators that allow correlated quadrat abundance estimates, even for quadrats in different sampling strata. Correlated quadrat abundance estimates based on mark–recapture or distance sampling methods occur...

ABUNDANT OR RARE? A HYBRID APPROACH FOR DETERMINING SPECIES RELATIVE ABUNDANCE AT AN ECOREGOIONAL SCALE - 2014

EPA Science Inventory

Everyone knows what abundant and rare species are, but quantifying the concept proves elusive. As part of an EPA/USGS project to assess near-coastal species vulnerability to climate change affects, we designed a hybrid approach to determine species relative abundance at an ecoreg...

Epipelagic mesozooplankton succession and community structure over a marine ouffall area in the northeastern South China Sea.

PubMed

Tseng, Li Chun; Kumar, Ram; Dahms, Hans Uwe; Chen, Chun Te; Chen, Qing Chao; Hwang, Jiang Shiou

2008-05-01

This study analyses distribution and abundance patterns of mesozooplankton communities at 13 stations in the coastal waters over a marine outfall area in the northeastern South China Sea. Cruises were conducted in March, June and September 2002, and plankton samples were collected with a 333 microm North Pacific net. The Mesozooplankton was dominated by calanoid Copepods, Cladocera, Chaetognatha and Pteropoda. Stations located near the entrance of the harbor provided a relatively higher abundance of Noctilucales and Radiolarians. In total, 20 zooplankton groups were identified in which, Calanoida, Cladocera, Chaetognatha, Pteropoda, Poecilostomatoida and Appendicularia comprised 92.77% of the total zooplankton abundance. Copepoda dominated in all three cruises, comprising 65.32% of the total mesozooplankton abundance. Samples collected in June recorded higher mesozooplankton abundance than March and September samples. Onshore stations recorded higher BOD values, higher abundance of Noctilucales and Radiolarians and a relativelylower abundance of the overall mesozooplankton. Total mesozooplankton abundance did not correlate significantly with temperature, pH, or dissolved oxygen, but correlated negatively with BOD.

Plague epizootic cycles in Central Asia.

PubMed

Reijniers, Jonas; Begon, Mike; Ageyev, Vladimir S; Leirs, Herwig

2014-06-01

Infection thresholds, widely used in disease epidemiology, may operate on host abundance and, if present, on vector abundance. For wildlife populations, host and vector abundances often vary greatly across years and consequently the threshold may be crossed regularly, both up- and downward. Moreover, vector and host abundances may be interdependent, which may affect the infection dynamics. Theory predicts that if the relevant abundance, or combination of abundances, is above the threshold, then the infection is able to spread; if not, it is bound to fade out. In practice, though, the observed level of infection may depend more on past than on current abundances. Here, we study the temporal dynamics of plague (Yersinia pestis infection), its vector (flea) and its host (great gerbil) in the PreBalkhash region in Kazakhstan. We describe how host and vector abundances interact over time and how this interaction drives the dynamics of the system around the infection threshold, consequently affecting the proportion of plague-infected sectors. We also explore the importance of the interplay between biological and detectability delays in generating the observed dynamics.

Method for hyperspectral imagery exploitation and pixel spectral unmixing

NASA Technical Reports Server (NTRS)

Lin, Ching-Fang (Inventor)

2003-01-01

An efficiently hybrid approach to exploit hyperspectral imagery and unmix spectral pixels. This hybrid approach uses a genetic algorithm to solve the abundance vector for the first pixel of a hyperspectral image cube. This abundance vector is used as initial state in a robust filter to derive the abundance estimate for the next pixel. By using Kalman filter, the abundance estimate for a pixel can be obtained in one iteration procedure which is much fast than genetic algorithm. The output of the robust filter is fed to genetic algorithm again to derive accurate abundance estimate for the current pixel. The using of robust filter solution as starting point of the genetic algorithm speeds up the evolution of the genetic algorithm. After obtaining the accurate abundance estimate, the procedure goes to next pixel, and uses the output of genetic algorithm as the previous state estimate to derive abundance estimate for this pixel using robust filter. And again use the genetic algorithm to derive accurate abundance estimate efficiently based on the robust filter solution. This iteration continues until pixels in a hyperspectral image cube end.

A general class of multinomial mixture models for anuran calling survey data

USGS Publications Warehouse

Royle, J. Andrew; Link, W.A.

2005-01-01

We propose a general framework for modeling anuran abundance using data collected from commonly used calling surveys. The data generated from calling surveys are indices of calling intensity (vocalization of males) that do not have a precise link to actual population size and are sensitive to factors that influence anuran behavior. We formulate a model for calling-index data in terms of the maximum potential calling index that could be observed at a site (the 'latent abundance class'), given its underlying breeding population, and we focus attention on estimating the distribution of this latent abundance class. A critical consideration in estimating the latent structure is imperfect detection, which causes the observed abundance index to be less than or equal to the latent abundance class. We specify a multinomial sampling model for the observed abundance index that is conditional on the latent abundance class. Estimation of the latent abundance class distribution is based on the marginal likelihood of the index data, having integrated over the latent class distribution. We apply the proposed modeling framework to data collected as part of the North American Amphibian Monitoring Program (NAAMP).

Dynamical Dark Matter from thermal freeze-out

NASA Astrophysics Data System (ADS)

Dienes, Keith R.; Fennick, Jacob; Kumar, Jason; Thomas, Brooks

2018-03-01

In the Dynamical Dark-Matter (DDM) framework, the dark sector comprises a large number of constituent dark particles whose individual masses, lifetimes, and cosmological abundances obey specific scaling relations with respect to each other. In particular, the most natural versions of this framework tend to require a spectrum of cosmological abundances which scale inversely with mass, so that dark-sector states with larger masses have smaller abundances. Thus far, DDM model-building has primarily relied on nonthermal mechanisms for abundance generation such as misalignment production, since these mechanisms give rise to abundances that have this property. By contrast, the simplest versions of thermal freeze-out tend to produce abundances that increase, rather than decrease, with the mass of the dark-matter component. In this paper, we demonstrate that there exist relatively simple modifications of the traditional thermal freeze-out mechanism which "flip" the resulting abundance spectrum, producing abundances that scale inversely with mass. Moreover, we demonstrate that a far broader variety of scaling relations between lifetimes, abundances, and masses can emerge through thermal freeze-out than through the nonthermal mechanisms previously considered for DDM ensembles. The results of this paper thus extend the DDM framework into the thermal domain and essentially allow us to "design" our resulting DDM ensembles at will in order to realize a rich array of resulting dark-matter phenomenologies.

Using long-term data to predict fish abundance: the case of Prochilodus lineatus (Characiformes, Prochilodontidae) in the intensely regulated upper Paraná River

USGS Publications Warehouse

Piana, Pitágoras A.; Cardoso, Bárbara F.; Dias, Joilson; Gomes, Luiz C.; Agostinho, Angelo A.; Miranda, Leandro E.

2017-01-01

Populations show spatial-temporal fluctuations in abundance, partly due to random processes and partly due to self-regulatory processes. We evaluated the effects of various external factors on the population numerical abundance of curimba Prochilodus lineatus in the upper Paraná River floodplain, Brazil, over a 19-year period. Panel data analysis was applied to examine the structure of temporal and spatial abundance while controlling auto-regressive processes and spatial non-homogeneity variances that often obscure relationships. As sources of population variation, we considered predation, competition, selected abiotic variables, construction of a dam upstream of the study area, water level and flood intensity during the spawning period. We found that biological interactions (predation and competition) were not significantly related to variations in curimba abundance; specific conductance was a space indicator of abundance, apparently linked to the biology of the species; intensity of floods determined inter-annual variation in abundances; Porto Primavera Dam negatively impacted the abundances at sites in the floodplain directly affected by discharges from the dam. Panel data analysis was a powerful tool that identified the need for intense flooding to maintain high abundances of curimba in the upper Paraná River. We believe our results apply to other species with similar life strategy.

[Comparison of acetonitrile, ethanol and chromatographic column to eliminate high-abundance proteins in human serum].

PubMed

Li, Yin; Liao, Ming; He, Xiao; Zhou, Yi; Luo, Rong; Li, Hongtao; Wang, Yun; He, Min

2012-11-01

To compare the effects of acetonitrile precipitation, ethanol precipitation and multiple affinity chromatography column Human 14 removal to eliminate high-abundance proteins in human serum. Elimination of serum high-abundance proteins performed with acetonitrile precipitation, ethanol precipitation and multiple affinity chromatography column Human 14 removal. Bis-Tris Mini Gels electrophoresis and two-dimensional gel electrophoresis to detect the effect. Grey value analysis from 1-DE figure showed that after serum processed by acetonitrile method, multiple affinity chromatography column Human 14 removal method and ethanol method, the grey value of albumin changed into 157.2, 40.8 and 8.2 respectively from the original value of 19. 2-DE analysis results indicated that using multiple affinity chromatography column Human 14 method, the protein points noticeable increased by 137 compared to the original serum. After processed by acetonitrile method and ethanol method, the protein point reduced, but the low abundance protein point emerged. The acetonitrile precipitation could eliminate the vast majority of high abundance proteins in serum and gain more proteins of low molecular weight, ethanol precipitation could eliminate part of high abundance proteins in serum, but low abundance proteins less harvested, and multiple affinity chromatography column Human 14 method could effectively removed the high abundance proteins, and keep a large number of low abundance proteins.

Efficacy of time-lapse photography and repeated counts abundance estimation for white-tailed deer populations

USGS Publications Warehouse

Keever, Allison; McGowan, Conor P.; Ditchkoff, Stephen S.; Acker, S.A.; Grand, James B.; Newbolt, Chad H.

2017-01-01

Automated cameras have become increasingly common for monitoring wildlife populations and estimating abundance. Most analytical methods, however, fail to account for incomplete and variable detection probabilities, which biases abundance estimates. Methods which do account for detection have not been thoroughly tested, and those that have been tested were compared to other methods of abundance estimation. The goal of this study was to evaluate the accuracy and effectiveness of the N-mixture method, which explicitly incorporates detection probability, to monitor white-tailed deer (Odocoileus virginianus) by using camera surveys and a known, marked population to collect data and estimate abundance. Motion-triggered camera surveys were conducted at Auburn University’s deer research facility in 2010. Abundance estimates were generated using N-mixture models and compared to the known number of marked deer in the population. We compared abundance estimates generated from a decreasing number of survey days used in analysis and by time periods (DAY, NIGHT, SUNRISE, SUNSET, CREPUSCULAR, ALL TIMES). Accurate abundance estimates were generated using 24 h of data and nighttime only data. Accuracy of abundance estimates increased with increasing number of survey days until day 5, and there was no improvement with additional data. This suggests that, for our system, 5-day camera surveys conducted at night were adequate for abundance estimation and population monitoring. Further, our study demonstrates that camera surveys and N-mixture models may be a highly effective method for estimation and monitoring of ungulate populations.

Distribution and abundance of black bass in Skiatook Lake, Oklahoma, after introduction of smallmouth bass and a liberalized harvest regulation on spotted bass

USGS Publications Warehouse

Long, James M.; Fisher, William L.

2005-01-01

We conducted a 3-year study to examine the trends in abundance and distribution of three sympatric black bass species (Micropterus) in an Oklahoma reservoir after implementation of a differential harvest regulation to reduce the abundance of spotted bass M. punctulatus and after stocking nonnative smallmouth bass M. dolomieu. Largemouth bass M. salmoides were stocked in Skiatook Lake, Oklahoma, immediately after its creation in 1984 to supplement the existing population in the watershed. Nonnative smallmouth bass were stocked in 1990, and their abundance and distribution have increased ever since. Native spotted bass, which have less fishery value than the other two black bass species, increased fivefold in abundance in 1994, became the predominant black bass species by at least 1996, and appeared to displace largemouth bass from many habitats. From boat-mounted electrofishing sampling conducted in April and May 1997–1999, we found that spotted bass abundance (proportion and catch per hour) had decreased while smallmouth bass abundance and distribution within the reservoir steadily increased. Largemouth bass abundance did not change among years. Throughout our study period, spotted bass was always the most abundant black bass species where differences in abundance were found. Our results suggest that the continually expanding smallmouth bass population is displacing spotted bass from many of their formerly used habitats, much like spotted bass had displaced largemouth bass by 1996.

Relating large-scale climate variability to local species abundance: ENSO forcing and shrimp in Breton Sound, Louisiana, USA

USGS Publications Warehouse

Piazza, Bryan P.; LaPeyre, Megan K.; Keim, B.D.

2010-01-01

Climate creates environmental constraints (filters) that affect the abundance and distribution of species. In estuaries, these constraints often result from variability in water flow properties and environmental conditions (i.e. water flow, salinity, water temperature) and can have significant effects on the abundance and distribution of commercially important nekton species. We investigated links between large-scale climate variability and juvenile brown shrimp Farfantepenaeus aztecus abundance in Breton Sound estuary, Louisiana (USA). Our goals were to (1) determine if a teleconnection exists between local juvenile brown shrimp abundance and the El Niño Southern Oscillation (ENSO) and (2) relate that linkage to environmental constraints that may affect juvenile brown shrimp recruitment to, and survival in, the estuary. Our results identified a teleconnection between winter ENSO conditions and juvenile brown shrimp abundance in Breton Sound estuary the following spring. The physical connection results from the impact of ENSO on winter weather conditions in Breton Sound (air pressure, temperature, and precipitation). Juvenile brown shrimp abundance effects lagged ENSO by 3 mo: lower than average abundances of juvenile brown shrimp were caught in springs following winter El Niño events, and higher than average abundances of brown shrimp were caught in springs following La Niña winters. Salinity was the dominant ENSO-forced environmental filter for juvenile brown shrimp. Spring salinity was cumulatively forced by winter river discharge, winter wind forcing, and spring precipitation. Thus, predicting brown shrimp abundance requires incorporating climate variability into models.

Temporal Dynamics of Arthropods on Six Tree Species in Dry Woodlands on the Caribbean Island of Puerto Rico

PubMed Central

Beltrán, William; Wunderle, Joseph M.

2014-01-01

Abstract The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis–Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L. , Bucida buceras L. , Pithecellobium dulce , and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora , (Swartz) De Candolle, Pi. dulce , Leucaena leucocephala , and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. PMID:25502036

Interactive effects of prey and weather on golden eagle reproduction

USGS Publications Warehouse

Steenhof, Karen; Kochert, Michael N.; McDonald, T.L.

1997-01-01

1. The reproduction of the golden eagle Aquila chrysaetos was studied in southwestern Idaho for 23 years, and the relationship between eagle reproduction and jackrabbit Lepus californicus abundance, weather factors, and their interactions, was modelled using general linear models. Backward elimination procedures were used to arrive at parsimonious models.2. The number of golden eagle pairs occupying nesting territories each year showed a significant decline through time that was unrelated to either annual rabbit abundance or winter severity. However, eagle hatching dates were significantly related to both winter severity and jackrabbit abundance. Eagles hatched earlier when jackrabbits were abundant, and they hatched later after severe winters.3. Jackrabbit abundance influenced the proportion of pairs that laid eggs, the proportion of pairs that were successful, mean brood size at fledging, and the number of young fledged per pair. Weather interacted with prey to influence eagle reproductive rates.4. Both jackrabbit abundance and winter severity were important in predicting the percentage of eagle pairs that laid eggs. Percentage laying was related positively to jackrabbit abundance and inversely related to winter severity.5. The variables most useful in predicting percentage of laying pairs successful were rabbit abundance and the number of extremely hot days during brood-rearing. The number of hot days and rabbit abundance were also significant in a model predicting eagle brood size at fledging. Both success and brood size were positively related to jackrabbit abundance and inversely related to the frequency of hot days in spring.6. Eagle reproduction was limited by rabbit abundance during approximately twothirds of the years studied. Weather influenced how severely eagle reproduction declined in those years.7. This study demonstrates that prey and weather can interact to limit a large raptor population's productivity. Smaller raptors could be affected more strongly, especially in colder or wetter climates.

Temporal dynamics of arthropods on six tree species in dry woodlands on the Caribbean Island of Puerto Rico.

PubMed

Beltrán, William; Wunderle, Joseph M

2014-01-01

The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis-Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L., Bucida buceras L., Pithecellobium dulce, and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora, (Swartz) De Candolle, Pi. dulce, Leucaena leucocephala, and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

CHEMICAL ABUNDANCES IN A SAMPLE OF RED GIANTS IN THE OPEN CLUSTER NGC 2420 FROM APOGEE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Souto, Diogo; Cunha, K.; Smith, V.

NGC 2420 is a ∼2 Gyr old well-populated open cluster that lies about 2 kpc beyond the solar circle, in the general direction of the Galactic anti-center. Most previous abundance studies have found this cluster to be mildly metal-poor, but with a large scatter in the obtained metallicities. Detailed chemical abundance distributions are derived for 12 red-giant members of NGC 2420 via a manual abundance analysis of high-resolution ( R = 22,500) near-infrared ( λ 1.5–1.7 μ m) spectra obtained from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. The sample analyzed contains six stars that are identified asmore » members of the first-ascent red giant branch (RGB), as well as six members of the red clump (RC). We find small scatter in the star-to-star abundances in NGC 2420, with a mean cluster abundance of [Fe/H] = −0.16 ± 0.04 for the 12 red giants. The internal abundance dispersion for all elements (C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Co and Ni) is also very small (∼0.03–0.06 dex), indicating a uniform cluster abundance distribution within the uncertainties. NGC 2420 is one of the clusters used to calibrate the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). The results from this manual analysis compare well with ASPCAP abundances for most of the elements studied, although for Na, Al, and V there are more significant offsets. No evidence of extra-mixing at the RGB luminosity bump is found in the {sup 12}C and {sup 14}N abundances from the pre-luminosity-bump RGB stars in comparison to the post-He core-flash RC stars.« less

Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. I. Signatures of Diffusion in the Open Cluster M67

NASA Astrophysics Data System (ADS)

Souto, Diogo; Cunha, Katia; Smith, Verne V.; Allende Prieto, C.; García-Hernández, D. A.; Pinsonneault, Marc; Holzer, Parker; Frinchaboy, Peter; Holtzman, Jon; Johnson, J. A.; Jönsson, Henrik; Majewski, Steven R.; Shetrone, Matthew; Sobeck, Jennifer; Stringfellow, Guy; Teske, Johanna; Zamora, Olga; Zasowski, Gail; Carrera, Ricardo; Stassun, Keivan; Fernandez-Trincado, J. G.; Villanova, Sandro; Minniti, Dante; Santana, Felipe

2018-04-01

Detailed chemical abundance distributions for 14 elements are derived for eight high-probability stellar members of the solar metallicity old open cluster M67 with an age of ∼4 Gyr. The eight stars consist of four pairs, with each pair occupying a distinct phase of stellar evolution: two G dwarfs, two turnoff stars, two G subgiants, and two red clump (RC) K giants. The abundance analysis uses near-IR high-resolution spectra (λ1.5–1.7 μm) from the Apache Point Observatory Galactic Evolution Experiment survey and derives abundances for C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe. Our derived stellar parameters and metallicity for 2M08510076+1153115 suggest that this star is a solar twin, exhibiting abundance differences relative to the Sun of ≤0.04 dex for all elements. Chemical homogeneity is found within each class of stars (∼0.02 dex), while significant abundance variations (∼0.05–0.20 dex) are found across the different evolutionary phases; the turnoff stars typically have the lowest abundances, while the RCs tend to have the largest. Non-LTE corrections to the LTE-derived abundances are unlikely to explain the differences. A detailed comparison of the derived Fe, Mg, Si, and Ca abundances with recently published surface abundances from stellar models that include chemical diffusion provides a good match between the observed and predicted abundances as a function of stellar mass. Such agreement would indicate the detection of chemical diffusion processes in the stellar members of M67.

The lithium abundances of a large sample of red giants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Y. J.; Tan, K. F.; Wang, L.

2014-04-20

The lithium abundances for 378 G/K giants are derived with non-local thermodynamic equilibrium correction considered. Among these are 23 stars that host planetary systems. The lithium abundance is investigated, as a function of metallicity, effective temperature, and rotational velocity, as well as the impact of a giant planet on G/K giants. The results show that the lithium abundance is a function of metallicity and effective temperature. The lithium abundance has no correlation with rotational velocity at v sin i < 10 km s{sup –1}. Giants with planets present lower lithium abundance and slow rotational velocity (v sin i < 4more » km s{sup –1}). Our sample includes three Li-rich G/K giants, 36 Li-normal stars, and 339 Li-depleted stars. The fraction of Li-rich stars in this sample agrees with the general rate of less than 1% in the literature, and the stars that show normal amounts of Li are supposed to possess the same abundance at the current interstellar medium. For the Li-depleted giants, Li-deficiency may have already taken place at the main sequence stage for many intermediate mass (1.5-5 M {sub ☉}) G/K giants. Finally, we present the lithium abundance and kinematic parameters for an enlarged sample of 565 giants using a compilation of the literature, and confirm that the lithium abundance is a function of metallicity and effective temperature. With the enlarged sample, we investigate the differences between the lithium abundance in thin-/thick-disk giants, which indicate that the lithium abundance in thick-disk giants is more depleted than that in thin-disk giants.« less

viral abundance distribution in deep waters of the Northern of South China Sea

NASA Astrophysics Data System (ADS)

He, Lei; Yin, Kedong

2017-04-01

Little is known about the vertical distribution and interaction of viruses and bacteria in the deep ocean water column. The vertical distribution of viral-like particles and bacterial abundance was investigated in the deep water column in the South China Sea during September 2005 along with salinity, temperature and dissolved oxygen. There were double maxima in the ratio of viral to bacterial abundance (VBR) in the water column: the subsurface maximum located at 50-100 m near the pycnocline layer, and the deep maximum at 800-1000 m. At the subsurface maximum of VBR, both viral and bacterial abundance were maximal in the water column, and at the deep maximum of VBR, both viral and bacterial abundance were low, but bacterial abundance was relatively lower than viral abundance. The subsurface VBR maximum coincided with the subsurface chlorophyll maximum while the deep VBR maximum coincided with the minimum in dissolved oxygen (2.91mg L-1). Therefore, we hypothesize that the two maxima were formed by different mechanisms. The subsurface VBR maximum was formed due to an increase in bacterial abundance resulting from the stimulation of abundant organic supply at the subsurface chlorophyll maximum, whereas the deep VBR maximum was formed due to a decrease in bacterial abundance caused by more limitation of organic matter at the oxygen minimum. The evidence suggests that viruses play an important role in controlling bacterial abundance in the deep water column due to the limitation of organic matter supply. In turn, this slows down the formation of the oxygen minimum in which oxygen may be otherwise lower. The mechanism has a great implication that viruses could control bacterial decomposition of organic matter, oxygen consumption and nutrient remineralization in the deep oceans.

Climate change likely to reduce orchid bee abundance even in climatic suitable sites.

PubMed

Faleiro, Frederico Valtuille; Nemésio, André; Loyola, Rafael

2018-06-01

Studies have tested whether model predictions based on species' occurrence can predict the spatial pattern of population abundance. The relationship between predicted environmental suitability and population abundance varies in shape, strength and predictive power. However, little attention has been paid to the congruence in predictions of different models fed with occurrence or abundance data, in particular when comparing metrics of climate change impact. Here, we used the ecological niche modeling fit with presence-absence and abundance data of orchid bees to predict the effect of climate change on species and assembly level distribution patterns. In addition, we assessed whether predictions of presence-absence models can be used as a proxy to abundance patterns. We obtained georeferenced abundance data of orchid bees (Hymenoptera: Apidae: Euglossina) in the Brazilian Atlantic Forest. Sampling method consisted in attracting male orchid bees to baits of at least five different aromatic compounds and collecting the individuals with entomological nets or bait traps. We limited abundance data to those obtained by similar standard sampling protocol to avoid bias in abundance estimation. We used boosted regression trees to model ecological niches and project them into six climate models and two Representative Concentration Pathways. We found that models based on species occurrences worked as a proxy for changes in population abundance when the output of the models were continuous; results were very different when outputs were discretized to binary predictions. We found an overall trend of diminishing abundance in the future, but a clear retention of climatically suitable sites too. Furthermore, geographic distance to gained climatic suitable areas can be very short, although it embraces great variation. Changes in species richness and turnover would be concentrated in western and southern Atlantic Forest. Our findings offer support to the ongoing debate of suitability-abundance models and can be used to support spatial conservation prioritization schemes and species triage in Atlantic Forest. © 2018 John Wiley & Sons Ltd.

Behavior of Abundances in Chemically Peculiar Dwarf and Subgiant A-Type Stars: HD 23193 and HD 170920

NASA Astrophysics Data System (ADS)

Kılıçoğlu, Tolgahan; Çalışkan, Şeyma; Ünal, Kübraözge

2018-01-01

To understand the origin of the abundance peculiarities of non-magnetic A-type stars, we present the first detailed chemical abundance analysis of a metallic line star HD 23193 (A2m) and an A-type subgiant HD 170920 (A5), which could have been a HgMn star on the main sequence. Our analysis is based on medium (R ∼ 14,000) and high (R ∼ 40,000) resolution spectroscopic data of the stars. The abundances of 18 elements are derived: C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Y, and Ba. The masses of HD 23193 and HD 170920 are estimated from evolutionary tracks as 2.3 ± 0.1 M ⊙ and 2.9 ± 0.1 M ⊙. The ages are found to be 635 ± 33 Myr for HD 23193 and 480 ± 50 Myr for HD 170920 using isochrones. The abundance pattern of HD 23193 shows deviations from solar values in the iron-peak elements and indicates remarkable overabundances of Sr (1.16), Y (1.03), and Ba (1.24) with respect to the solar abundances. We compare the derived abundances of this moderately rotating (v\\sin i =37.5 km s‑1) Am star to the theoretical chemical evolution models including rotational mixing. The theoretically predicted abundances resemble our derived abundance pattern, except for a few elements (Si and Cr). For HD 170920, we find nearly solar abundances, except for C (‑0.43), S (0.16), Ti (0.15), Ni (0.16), Zn (0.41), Y (0.57), and Ba (0.97). Its low rotational velocity (v\\sin i=14.5 km s‑1), reduced carbon abundance, and enhanced heavy element abundances suggest that the star is most likely an evolved HgMn star. Based on observations made at the TÜBITAK National Observatory (Program ID 14BRTT150–671), and the Ankara University Observatory, Turkey.

Climatic effects on mosquito abundance in Mediterranean wetlands

PubMed Central

2014-01-01

Background The impact of climate change on vector-borne diseases is highly controversial. One of the principal points of debate is whether or not climate influences mosquito abundance, a key factor in disease transmission. Methods To test this hypothesis, we analysed ten years of data (2003–2012) from biweekly surveys to assess inter-annual and seasonal relationships between the abundance of seven mosquito species known to be pathogen vectors (West Nile virus, Usutu virus, dirofilariasis and Plasmodium sp.) and several climatic variables in two wetlands in SW Spain. Results Within-season abundance patterns were related to climatic variables (i.e. temperature, rainfall, tide heights, relative humidity and photoperiod) that varied according to the mosquito species in question. Rainfall during winter months was positively related to Culex pipiens and Ochlerotatus detritus annual abundances. Annual maximum temperatures were non-linearly related to annual Cx. pipiens abundance, while annual mean temperatures were positively related to annual Ochlerotatus caspius abundance. Finally, we modelled shifts in mosquito abundances using the A2 and B2 temperature and rainfall climate change scenarios for the period 2011–2100. While Oc. caspius, an important anthropophilic species, may increase in abundance, no changes are expected for Cx. pipiens or the salt-marsh mosquito Oc. detritus. Conclusions Our results highlight that the effects of climate are species-specific, place-specific and non-linear and that linear approaches will therefore overestimate the effect of climate change on mosquito abundances at high temperatures. Climate warming does not necessarily lead to an increase in mosquito abundance in natural Mediterranean wetlands and will affect, above all, species such as Oc. caspius whose numbers are not closely linked to rainfall and are influenced, rather, by local tidal patterns and temperatures. The final impact of changes in vector abundance on disease frequency will depend on the direct and indirect effects of climate and other parameters related to pathogen amplification and spillover on humans and other vertebrates. PMID:25030527

Species-abundance--seed-size patterns within a plant community affected by grazing disturbance.

PubMed

Wu, Gao-lin; Shang, Zhan-huan; Zhu, Yuan-jun; Ding, Lu-ming; Wang, Dong

2015-04-01

Seed size has been advanced as a key factor that influences the dynamics of plant communities, but there are few empirical or theoretical predictions of how community dynamics progress based on seed size patterns. Information on the abundance of adults, seedlings, soil seed banks, seed rains, and the seed mass of 96 species was collected in alpine meadows of the Qinghai-Tibetan Plateau (China), which had different levels of grazing disturbance. The relationships between seed-mass-abundance patterns for adults, seedlings, the soil seed bank, and seed rain in the plant community were evaluated using regression models. Results showed that grazing levels affected the relationship between seed size and abundance properties of adult species, seedlings, and the soil seed bank, suggesting that there is a shift in seed-size--species-abundance relationships as a response to the grazing gradient. Grazing had no effect on the pattern of seed-size-seed-rain-abundance at four grazing levels. Grazing also had little effect on the pattern of seed-size--species-abundance and pattern of seed-size--soil-seed-bank-abundance in meadows with no grazing, light grazing, and moderate grazing), but there was a significant negative effect in meadows with heavy grazing. Grazing had little effect on the pattern of seed-size--seedling-abundance with no grazing, but had significant negative effects with light, moderate, and heavy grazing, and the |r| values increased with grazing levels. This indicated that increasing grazing pressure enhanced the advantage of smaller-seeded species in terms of the abundances of adult species, seedlings, and soil seed banks, whereas only the light grazing level promoted the seed rain abundance of larger-seeded species in the plant communities. This study suggests that grazing disturbances are favorable for increasing the species abundance for smaller-seeded species but not for the larger-seeded species in an alpine meadow community. Hence, there is a clear advantage of the smaller-seeded species over the larger-seeded species with increases in the grazing level.

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.

PubMed

Maron, John L; Laney Smith, Alyssa; Ortega, Yvette K; Pearson, Dean E; Callaway, Ragan M

2016-08-01

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil feedbacks for 10 target species that spanned a range of abundances in the field. In soil from both sites, plant-soil feedbacks were mostly negative, with more abundant species suffering greater negative feedbacks than rare species. In contrast, the average response to competition for each species was unrelated with its abundance in the field. We also determined how competitive response varied among our target species when plants competed in live vs. sterile soil. Interspecific competition reduced plant size, but the strength of this negative effect was unchanged by plant-soil feedbacks. Finally, when plants competed interspecifically, we asked how conspecific-trained, heterospecific-trained, and sterile soil influenced the competitive responses of our target species and how this varied depending on whether target species were abundant or rare in the field. Here, we found that both abundant and rare species were not as harmed by competition when they grew in heterospecific-trained soil compared to when they grew in conspecific-cultured soil. Abundant species were also not as harmed by competition when growing in sterile vs. conspecific-trained soil, but this was not the case for rare species. Our results suggest that abundant plants accrue species-specific soil pathogens to a greater extent than rare species. Thus, negative feedbacks may be critical for preventing abundant species from becoming even more abundant than rare species. © 2016 by the Ecological Society of America.

Global climate change will increase the abundance of symbiotic nitrogen-fixing trees in much of North America.

PubMed

Liao, Wenying; Menge, Duncan N L; Lichstein, Jeremy W; Ángeles-Pérez, Gregorio

2017-11-01

Symbiotic nitrogen (N)-fixing trees can drive N and carbon cycling and thus are critical components of future climate projections. Despite detailed understanding of how climate influences N-fixation enzyme activity and physiology, comparatively little is known about how climate influences N-fixing tree abundance. Here, we used forest inventory data from the USA and Mexico (>125,000 plots) along with climate data to address two questions: (1) How does the abundance distribution of N-fixing trees (rhizobial, actinorhizal, and both types together) vary with mean annual temperature (MAT) and precipitation (MAP)? (2) How will changing climate shift the abundance distribution of N-fixing trees? We found that rhizobial N-fixing trees were nearly absent below 15°C MAT, but above 15°C MAT, they increased in abundance as temperature rose. We found no evidence for a hump-shaped response to temperature throughout the range of our data. Rhizobial trees were more abundant in dry than in wet ecosystems. By contrast, actinorhizal trees peaked in abundance at 5-10°C MAT and were least abundant in areas with intermediate precipitation. Next, we used a climate-envelope approach to project how N-fixing tree relative abundance might change in the future. The climate-envelope projection showed that rhizobial N-fixing trees will likely become more abundant in many areas by 2080, particularly in the southern USA and western Mexico, due primarily to rising temperatures. Projections for actinorhizal N-fixing trees were more nuanced due to their nonmonotonic dependence on temperature and precipitation. Overall, the dominant trend is that warming will increase N-fixing tree abundance in much of the USA and Mexico, with large increases up to 40° North latitude. The quantitative link we provide between climate and N-fixing tree abundance can help improve the representation of symbiotic N fixation in Earth System Models. © 2017 John Wiley & Sons Ltd.

Efficient estimation of abundance for patchily distributed populations via two-phase, adaptive sampling.

USGS Publications Warehouse

Conroy, M.J.; Runge, J.P.; Barker, R.J.; Schofield, M.R.; Fonnesbeck, C.J.

2008-01-01

Many organisms are patchily distributed, with some patches occupied at high density, others at lower densities, and others not occupied. Estimation of overall abundance can be difficult and is inefficient via intensive approaches such as capture-mark-recapture (CMR) or distance sampling. We propose a two-phase sampling scheme and model in a Bayesian framework to estimate abundance for patchily distributed populations. In the first phase, occupancy is estimated by binomial detection samples taken on all selected sites, where selection may be of all sites available, or a random sample of sites. Detection can be by visual surveys, detection of sign, physical captures, or other approach. At the second phase, if a detection threshold is achieved, CMR or other intensive sampling is conducted via standard procedures (grids or webs) to estimate abundance. Detection and CMR data are then used in a joint likelihood to model probability of detection in the occupancy sample via an abundance-detection model. CMR modeling is used to estimate abundance for the abundance-detection relationship, which in turn is used to predict abundance at the remaining sites, where only detection data are collected. We present a full Bayesian modeling treatment of this problem, in which posterior inference on abundance and other parameters (detection, capture probability) is obtained under a variety of assumptions about spatial and individual sources of heterogeneity. We apply the approach to abundance estimation for two species of voles (Microtus spp.) in Montana, USA. We also use a simulation study to evaluate the frequentist properties of our procedure given known patterns in abundance and detection among sites as well as design criteria. For most population characteristics and designs considered, bias and mean-square error (MSE) were low, and coverage of true parameter values by Bayesian credibility intervals was near nominal. Our two-phase, adaptive approach allows efficient estimation of abundance of rare and patchily distributed species and is particularly appropriate when sampling in all patches is impossible, but a global estimate of abundance is required.

Vertical distributions and diel migrations of Euthecosomata in the northwest Sargasso Sea

NASA Astrophysics Data System (ADS)

Wormuth, John H.

1981-12-01

Vertical distributions and seasonal variations in abundance of nine abundant or frequent pteropod species or subspecies in the northwest Sargasso Sea are described. Factor analyses yielded two groups, diel migrators and non-migrators. In terms of water column abundances, tows taken in August and November are similar, as are tows in December and April. Most species show significant within-species agreement in depth distribution over the year but high variability in abundance. Regression analyses using environmental parameters as independent variables show significant correlations of species abundances with temperature.

Solar photospheric and coronal abundances from solar energetic particle measurements. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Breneman, H.

1985-01-01

Observations of solar energetic particles (SEP) from 22 solar flares in the 1977 to 1982 time period are reported. SEP abundances were obtained for all elements with 3 approximately less than Z approximately less than 30 except Li, Be, B, F, Sc, v, Co and Cu for which upper limits were obtained. Statistically meaningful abundances of several rare elements (P, Cl, K, Ti, and Mn) were determined for the first time, and the average abundance of the more abundant elements were determined with improved precision.

Multitrophic interactions mediate the effects of climate change on herbivore abundance.

PubMed

Robinson, Ayla; Inouye, David W; Ogilvie, Jane E; Mooney, Emily H

2017-10-01

Climate change can influence the abundance of insect herbivores through direct and indirect mechanisms. In this study, we evaluated multitrophic drivers of herbivore abundance for an aphid species (Aphis helianthi) in a subalpine food web consisting of a host plant (Ligusticum porteri), mutualist ants and predatory lygus bugs (Lygus spp.). We used a model-selection approach to determine which climate and host plant cues best predict year-to-year variation in insect phenology and abundance observed over 6 years. We complemented this observational study with experiments that determined how elevated temperature interacts with (1) host plant phenology and (2) the ant-aphid mutualism to determine aphid abundance. We found date of snowmelt to be the best predictor of yearly abundance of aphid and lygus bug abundance but the direction of this effect differed. Aphids achieved lower abundances in early snowmelt years likely due to increased abundance of lygus bug predators in these years. Elevating temperature of L. porteri flowering stalks reduced their quality as hosts for aphid populations. However, warming aphid colonies on host plants of similar quality increased population growth rates. Importantly, this effect was apparent even in the absence of ants. While we observed fewer ants tending colonies at elevated temperatures, these colonies also had reduced numbers of lygus bug predators. This suggests that mutualism with ants becomes less significant as temperature increases, which contrasts other ant-hemipteran systems. Our observational and experimental results show the importance of multitrophic species interactions for predicting the effect of climate change on the abundances of herbivores.

Niche modelling of marsh plants based on occurrence and abundance data.

PubMed

Lou, Yanjing; Gao, Chuanyu; Pan, Yanwen; Xue, Zhenshan; Liu, Ying; Tang, Zhanhui; Jiang, Ming; Lu, Xianguo; Rydin, Håkan

2018-03-01

The information of species' response (optimum or critical limits along environmental gradients) is a key to understanding ecological questions and to design management plans. A large number of plots (762) from 70 transects of 13 wetland sites in Northeast China were sampled along flooding gradient from marsh to wet meadow. Species response (abundance and occurrence) to flooding were modelled with Generalized Additive Models for 21 dominant plant species. We found that 20 of 21 species showed a significant response to flooding for the occurrence and abundance models, and four types of response were found: monotonically increasing, monotonically decreasing, skewed unimodal and symmetric unimodal. The species with monotonically increasing response have the deepest flooding optimum and widest niche width, followed by those with unimodal curve, and the monotonically decreasing ones have the smallest values. The optima and niche width (whether based on occurrence or abundance models) both significantly correlated with the frequency, but not with mean abundance. Abundance models outperformed occurrence models based on goodness of fit. The abundance models predicted a rather sharp shift from dominance of helophytes (Carex pseudo-curaica and C. lasiocarpa) to wet meadow species (Calamagrostis angustifolia and Carex appendiculata) if water levels drop from about 10cm above soil surface to below the surface. The defined optima and niche width based on the abundance models can be applied to better instruct restoration management. Given the time required to collect abundance data, an efficient strategy could be to monitor occurrence in many plots and abundance in a subset of these. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of landscape context on the abundance and diversity of bees in Mediterranean olive groves.

PubMed

Tscheulin, T; Neokosmidis, L; Petanidou, T; Settele, J

2011-10-01

The diversity and abundance of wild bees ensures the delivery of pollination services and the maintenance of ecosystem diversity. As previous studies carried out in Central Europe and the US have shown, bee diversity and abundance is influenced by the structure and the composition of the surrounding landscape. Comparable studies have so far not been carried out in the Mediterranean region. The present study examines the influence of Mediterranean landscape context on the diversity and abundance of wild bees. To do this, we sampled bees in 13 sites in olive groves on Lesvos Island, Greece. Bees were assigned to five categories consisting of three body size groups (small, medium and large bees), the single most abundant bee species (Lasioglossum marginatum) and all species combined. The influence of the landscape context on bee abundance and species richness was assessed at five radii (250, 500, 750, 1000 and 1250 m) from the centre of each site. We found that the abundance within bee groups was influenced differently by different landscape parameters and land covers, whereas species richness was unaffected. Generally, smaller bees' abundance was impacted by landscape parameters at smaller scales and larger bees at larger scales. The land cover that influenced bee abundance positively was olive grove, while phrygana, conifer forest, broad-leaved forest, cultivated land, rock, urban areas and sea had mostly negative or no impact. We stress the need for a holistic approach, including all land covers, when assessing the effects of landscape context on bee diversity and abundance in the Mediterranean.

Climatic, Edaphic Factors and Cropping History Help Predict Click Beetle (Coleoptera: Elateridae) (Agriotes spp.) Abundance.

PubMed

Kozina, A; Lemic, D; Bazok, R; Mikac, K M; Mclean, C M; Ivezić, M; Igrc Barčić, J

2015-01-01

It is assumed that the abundance of Agriotes wireworms (Coleoptera: Elateridae) is affected by agro-ecological factors such as climatic and edaphic factors and the crop/previous crop grown at the sites investigated. The aim of this study, conducted in three different geographic counties in Croatia from 2007 to 2009, was to determine the factors that influence the abundance of adult click beetle of the species Agriotes brevis Cand., Agriotes lineatus (L.), Agriotes obscurus (L.), Agriotes sputator (L.), and Agriotes ustulatus Schall. The mean annual air temperature, total rainfall, percentage of coarse and fine sand, coarse and fine silt and clay, the soil pH, and humus were investigated as potential factors that may influence abundance. Adult click beetle emergence was monitored using sex pheromone traps (YATLORf and VARb3). Exploratory data analysis was preformed via regression tree models and regional differences in Agriotes species' abundance were predicted based on the agro-ecological factors measured. It was found that the best overall predictor of A. brevis abundance was the previous crop grown. Conversely, the best predictor of A. lineatus abundance was the current crop being grown and the percentage of humus. The best predictor of A. obscurus abundance was soil pH in KCl. The best predictor of A. sputator abundance was rainfall. Finally, the best predictors of A. ustulatus abundance were soil pH in KCl and humus. These results may be useful in regional pest control programs or for predicting future outbreaks of these species. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Abundance and size distribution dynamics of abyssal epibenthic megafauna in the northeast Pacific.

PubMed

Ruhl, Henry A

2007-05-01

The importance of interannual variation in deep-sea abundances is now becoming recognized. There is, however, relatively little known about what processes dominate the observed fluctuations. The abundance and size distribution of the megabenthos have been examined here using a towed camera system at a deep-sea station in the northeast Pacific (Station M) from 1989 to 2004. This 16-year study included 52 roughly seasonal transects averaging 1.2 km in length with over 35600 photographic frames analyzed. Mobile epibenthic megafauna at 4100 m depth have exhibited interannual scale changes in abundance from one to three orders of magnitude. Increases in abundance have now been significantly linked to decreases in mean body size, suggesting that accruals in abundance probably result from the recruitment of young individuals. Examinations of size-frequency histograms indicate several possible recruitment events. Shifts in size-frequency distributions were also used to make basic estimations of individual growth rates from 1 to 6 mm/month, depending on the taxon. Regional intensification in reproduction followed by recruitment within the study area could explain the majority of observed accruals in abundance. Although some adult migration is certainly probable in accounting for local variation in abundances, the slow movements of benthic life stages restrict regional migrations for most taxa. Negative competitive interactions and survivorship may explain the precipitous declines of some taxa. This and other studies have shown that abundances from protozoans to large benthic invertebrates and fishes all have undergone significant fluctuations in abundance at Station M over periods of weeks to years.

Contrasting changes in the abundance and diversity of North American bird assemblages from 1971 to 2010.

PubMed

Schipper, Aafke M; Belmaker, Jonathan; de Miranda, Murilo Dantas; Navarro, Laetitia M; Böhning-Gaese, Katrin; Costello, Mark J; Dornelas, Maria; Foppen, Ruud; Hortal, Joaquín; Huijbregts, Mark A J; Martín-López, Berta; Pettorelli, Nathalie; Queiroz, Cibele; Rossberg, Axel G; Santini, Luca; Schiffers, Katja; Steinmann, Zoran J N; Visconti, Piero; Rondinini, Carlo; Pereira, Henrique M

2016-12-01

Although it is generally recognized that global biodiversity is declining, few studies have examined long-term changes in multiple biodiversity dimensions simultaneously. In this study, we quantified and compared temporal changes in the abundance, taxonomic diversity, functional diversity, and phylogenetic diversity of bird assemblages, using roadside monitoring data of the North American Breeding Bird Survey from 1971 to 2010. We calculated 12 abundance and diversity metrics based on 5-year average abundances of 519 species for each of 768 monitoring routes. We did this for all bird species together as well as for four subgroups based on breeding habitat affinity (grassland, woodland, wetland, and shrubland breeders). The majority of the biodiversity metrics increased or remained constant over the study period, whereas the overall abundance of birds showed a pronounced decrease, primarily driven by declines of the most abundant species. These results highlight how stable or even increasing metrics of taxonomic, functional, or phylogenetic diversity may occur in parallel with substantial losses of individuals. We further found that patterns of change differed among the species subgroups, with both abundance and diversity increasing for woodland birds and decreasing for grassland breeders. The contrasting changes between abundance and diversity and among the breeding habitat groups underscore the relevance of a multifaceted approach to measuring biodiversity change. Our findings further stress the importance of monitoring the overall abundance of individuals in addition to metrics of taxonomic, functional, or phylogenetic diversity, thus confirming the importance of population abundance as an essential biodiversity variable. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Terrestrial liming benefits birds in an acidified forest in the northeast.

PubMed

Pabian, Sarah E; Brittingham, Margaret C

2007-12-01

Studies in Europe have reported negative effects of acid deposition on forest birds, and research in North America has identified links between forest bird abundance and rates of acid deposition. We examined the bird community in an acidified forest in central Pennsylvania (USA) and evaluated the effects of terrestrial lime application on birds. We used a before-after control-impact (BACI) study design, with one year of observation before (2003) and three years after lime application (2004, 2005, and 2006). Between the 2003 and 2004 field seasons, 4500 kg/ha of dolomitic lime were applied to two of four 100-ha watersheds. Each year, we monitored bird abundance and Ovenbird (Seiurus aurocapilla) eggshell thickness and territory size. Soil and snail abundance data were also collected. The bird community and territory size results indicated that the study area may be providing low-quality habitat for forest birds, perhaps as a result of acid deposition. We found lower forest bird abundances than have been found in less acidified areas of Pennsylvania, and larger Ovenbird territory sizes than have been found in other studies. We found a significant positive relationship between soil calcium and bird abundance, indicating that soil calcium may affect bird abundance. Liming increased soil calcium and pH and led to increased snail and bird abundances. After liming, bird abundance was positively related to snail abundance. No significant changes occurred in Ovenbird territory size or eggshell thickness. Our results suggest that acid deposition could be responsible for reduced bird abundance, and that liming is a potential mitigation technique.

Growth and abundance of Pacific Sand Lance, Ammodytes hexapterus, under differing oceanographic regimes

USGS Publications Warehouse

Robards, Martin D.; Gray, Floyd; Piatt, John F.

2002-01-01

Dramatic changes in seabird and marine mammal stocks in the Gulf of Alaska have been linked to shifts in abundance and composition of forage fish stocks over the past 20 years. The relative value (e.g., size and condition of individual fish, abundance) of specific forage fish stocks to predators under temporally changing oceanographic regimes is also expected to vary. We inferred potential temporal responses in abundance, growth, and age structure of a key forage fish, sand lance, by studying across spatially different oceanographic regimes. Marked meso-scale differences in abundance, growth, and mortality existed in conjunction with these differing regimes. Growth rate within stocks (between years) was positively correlated with temperature. However, this relationship did not exist among stocks (locations) and differing growth rates were better correlated to marine productivity. Sand lance were least abundant and grew slowest at the warmest site (Chisik Island), an area of limited habitat and low food abundance. Abundance and growth of juvenile sand lance was highest at the coolest site (Barren Islands), an area of highly productive upwelled waters. Sand lance at two sites located oceanographically between the Barren Islands and Chisik Island (inner- and outer-Kachemak Bay) displayed correspondingly intermediate abundance and growth. Resident predators at these sites are presented with markedly different numbers and quality of this key prey species. Our results suggest that at the decadal scale, Gulf of Alaska forage fish such as sand lance are probably more profoundly affected by changes in abundance and quality of their planktonic food, than by temperature alone.

Quantitative Molecular Detection of Putative Periodontal Pathogens in Clinically Healthy and Periodontally Diseased Subjects

PubMed Central

Göhler, André; Hetzer, Adrian; Holtfreter, Birte; Geisel, Marie Henrike; Schmidt, Carsten Oliver; Steinmetz, Ivo; Kocher, Thomas

2014-01-01

Periodontitis is a multi-microbial oral infection with high prevalence among adults. Putative oral pathogens are commonly found in periodontally diseased individuals. However, these organisms can be also detected in the oral cavity of healthy subjects. This leads to the hypothesis, that alterations in the proportion of these organisms relative to the total amount of oral microorganisms, namely their abundance, rather than their simple presence might be important in the transition from health to disease. Therefore, we developed a quantitative molecular method to determine the abundance of various oral microorganisms and the portion of bacterial and archaeal nucleic acid relative to the total nucleic acid extracted from individual samples. We applied quantitative real-time PCRs targeting single-copy genes of periodontal bacteria and 16S-rRNA genes of Bacteria and Archaea. Testing tongue scrapings of 88 matched pairs of periodontally diseased and healthy subjects revealed a significantly higher abundance of P. gingivalis and a higher total bacterial abundance in diseased subjects. In fully adjusted models the risk of being periodontally diseased was significantly higher in subjects with high P. gingivalis and total bacterial abundance. Interestingly, we found that moderate abundances of A. actinomycetemcomitans were associated with reduced risk for periodontal disease compared to subjects with low abundances, whereas for high abundances, this protective effect leveled off. Moderate archaeal abundances were health associated compared to subjects with low abundances. In conclusion, our methodological approach unraveled associations of the oral flora with periodontal disease, which would have gone undetected if only qualitative data had been determined. PMID:25029268

Mutation abundance affects the therapeutic efficacy of EGFR-TKI in patients with advanced lung adenocarcinoma: A retrospective analysis.

PubMed

Wang, Huijuan; Zhang, Mina; Tang, Wanyu; Ma, Jie; Wei, Bing; Niu, Yuanyuan; Zhang, Guowei; Li, Peng; Yan, Xiangtao; Ma, Zhiyong

2018-03-22

To investigate the influence of mutation abundance and sites of epidermal growth factor receptor (EGFR) on therapeutic efficacies of EGFR-tyrosine kinase inhibitor (EGFR-TKIs) treatments of patients with advanced non-small cell lung carcinoma (NSCLC). EGFR mutational sites and mutation abundance were analyzed by amplification refractory mutation system (ARMS) in paraffin-embedded tissue sections taken from primary or metastatic tumors of 194 NSCLC patients. The median progression-free survival (PFS) time of the enrolled patients was 9.3 months (95% CI, 8.2-10.8 months). The PFS was significantly different with EGFR gene mutation abundance after EGFR-TKI therapy (P = 0.014). The median PFS was significantly longer when the cut-off value of EGFR mutation abundance of exon 19 or exon 21, and solely exon 19 was > 26.7% and 61.8%, respectively. For patients who received EGFR-TKI as first-line treatment, the median PFS was significantly longer in the high mutation abundance group than in the low mutation abundance group (12.7 vs 8.7 months, P = 0.002). The PFS benefits were greater in patients with a higher abundance of exon 19 deletion mutations in the EGFR gene after EGFR-TKI treatment and first line EGFR-TKI treatment led to improved PFS in high mutation abundance patients.

Predictors of leafhopper abundance and richness in a coffee agroecosystem in Chiapas, Mexico.

PubMed

Burdine, Justin D; Domínguez Martínez, Gabriel H; Philpott, Stacy M

2014-04-01

Coffee agroecosystems with a vegetatively complex shade canopy contain high levels of biodiversity. However, as coffee management is intensified, diversity may be lost. Most biodiversity studies in coffee agroecosystems have examined predators and not herbivores, despite their importance as potential coffee pests and coffee disease vectors. We sampled one abundant herbivore group of leafhoppers on an organic coffee farm in Chiapas, Mexico. We sampled leafhoppers with elevated pan traps in high- and moderate-shade coffee during the dry and wet seasons of 2011. The two major objectives were to 1) compare leafhopper abundance and richness during the wet and dry seasons and 2) examine the correlations between habitat characteristics (e.g., vegetation, elevation, and presence of aggressive ants) and leafhopper richness and abundance. We collected 2,351 leafhoppers, representing eight tribes and 64 morphospecies. Leafhopper abundance was higher in the dry season than in the wet season. Likewise, leafhopper richness was higher in the dry season. Several vegetation and other habitat characteristics correlated with abundance and richness of leafhoppers. The number of Inga trees positively correlated with leafhopper abundance, and other significant correlates of abundance included vegetation complexity. Leafhopper richness was correlated with the number of Inga trees. As leafhoppers transmit important coffee diseases, understanding the specific habitat factors correlating with changes in abundance and richness may help predict future disease outbreaks.

Context-specific parasitism in Tubifex tubifex in geothermally influenced stream reaches in Yellowstone National Park

USGS Publications Warehouse

Alexander, Julie D.; Kerans, Billie L.; Koel, Todd M.; Rasmussen, Charlotte

2011-01-01

Parasites can regulate host abundance and influence the composition and structure of communities. However, host-parasite interactions might be context-specific if environmental conditions can alter the outcome of parasitism and disease. An understanding of how host-parasite interactions might change in different contexts will be useful for predicting and managing disease against a background of anthropogenic environmental change. We examined the ecology of Myxobolus cerebralis, the parasite that causes whirling disease in salmonids, and its obligate host, Tubifex tubifex, in geothermally variable stream reaches in Yellowstone National Park. We identified reaches in 4 categories of geothermal influence, which were characterized by variable substrates, temperatures, specific conductivities, and pH. In each reach, we measured aspects of host ecology (abundance, relative abundance, size, and genotype of T. tubifex), parasite ecology (infection prevalence in T. tubifex and abundance of M. cerebralis-infected T. tubifex), and risk to fish of contracting whirling disease. Tubifex tubifex abundance was high all in reaches characterized by geothermal influence, whereas abundance of M. cerebralis-infected T. tubifex was high only in reaches characterized by intermediate geothermal influence. We suggest that habitat had a contextual effect on parasitism in the oligochaete host. Abundance of infected hosts appeared to depend on host abundance in all reach types except those with high geothermal influence, where abundance of infected hosts depended on environmental factors.

Abundance of red spruce regeneration across spruce-hardwood ecotones at Gaudineer Knob, West Virginia

Treesearch

Albert E. Mayfield; Ray R. Hicks

2010-01-01

The abundance of red spruce (Picea rubens Sarg.) in the Central Appalachian Mountains has been drastically reduced over the past 100 to 150 years. The purpose of this study was to examine the potential for increases in the relative abundance of overstory red spruce in a Central Appalachian, high-elevation forest by measuring the abundance of red...

A new solar carbon abundance based on non-LTE CN molecular spectra

NASA Technical Reports Server (NTRS)

Mount, G. H.; Linsky, J. L.

1975-01-01

A detailed non-LTE analysis of solar CN spectra strongly suggest a revised carbon abundance for the sun. We recommend a value of log carbon abundance = 8.35 plus or minus 0.15 which is significantly lower than the presently accepted value of log carbon abundance = 8.55. This revision may have important consequences in astrophysics.

Impacts of macro - and microplastic on macrozoobenthos abundance in intertidal zone

NASA Astrophysics Data System (ADS)

Bangun, A. P.; Wahyuningsih, H.; Muhtadi, A.

2018-02-01

Plastics pollution in coastal areas is one of the topics that have received more attention over the past few years. The intertidal zone is a waters area that is directly affected by contamination of plastic waste from land and sea. The purpose of this study was to analyze the types and abundance of plastic waste in the intertidal zone and its impact on macrozoobenthos abundance. This research was conducted at Pesisir Desa Jaring Halus in February-April 2017. Macrozoobenthos and macro - micro plastic were collected by using quadratic transect. Sediments were collected with a core, to a depth of 30 cm. Microplastic and macroplastic abundances were analyzed using separation of sediment density and hand sorting. The dominant micro plastic types were film (52.30%), fiber (24.88%), fragments (22.74%), followed by pellets (0.1%). The total number of microplastics were 326,33 items and macro plastic were 308 items. Macroplastic abundance is positively correlated with microplastic (0.765). The abundance of macrozoobenthos is negatively correlated with microplastic abundance (-0.368) and with macro plastic abundance (-0.633). The management strategies were suggested clean up marine debris, decrease plastic using and built up the station of debris processing.

Virioplankton dynamics are related to eutrophication levels in a tropical urbanized bay

PubMed Central

Cabral, Anderson S.; Lessa, Mariana M.; Junger, Pedro C.; Thompson, Fabiano L.; Paranhos, Rodolfo

2017-01-01

Virioplankton are an important and abundant biological component of marine and freshwater ecosystems. Often overlooked, aquatic viruses play an important role in biogeochemical cycles on a global scale, infecting both autotrophic and heterotrophic microbes. Viral diversity, abundance, and viral interactions at different trophic levels in aqueous environments are not well understood. Tropical ecosystems are less frequently studied than temperate ecosystems, but could provide new insights into how physical and chemical variability can shape or force microbial community changes. In this study, we found high viral abundance values in Guanabara Bay relative to other estuaries around the world. Viral abundance was positively correlated with bacterioplankton abundance and chlorophyll a concentrations. Moreover, prokaryotic and viral abundance were positively correlated with eutrophication, especially in surface waters. These results provide novel baseline data on the quantitative distribution of aquatic viruses in tropical estuaries. They also provide new information on a complex and dynamic relationship in which environmental factors influence the abundance of bacterial hosts and consequently their viruses. Guanabara Bay is characterized by spatial and seasonal variations, and the eutrophication process is the most important factor explaining the structuring of virioplankton abundance and distribution in this tropical urbanized bay. PMID:28362842

Exploring the Milky Way Disk Abundance Transition Zone Rgc 10 kpc with Open Clusters

NASA Astrophysics Data System (ADS)

Jacobson, Heather R.; Friel, E.; Pilachowski, C.

2009-01-01

Recent studies of the radial chemical abundance distribution among stellar populations in the Galactic disk have shown a change in the abundance trend at galactocentric distance Rgc 10 kpc, as first noted by Twarog et al. (1997). Here the gradient in [Fe/H] with distance appears to vanish, with abundances of stars at greater distances dropping to [Fe/H] -0.3, independent of galactocentric distance. Much is still unknown about the exact nature of the transition from inner to outer disk, and it is still uncertain if the outer disk has had a distinct evolutionary history from that of the inner disk. While current chemical evolution models can well match the outer disk abundances (Cescutti et al. 2007), abundances of many more stars at Rgc 9-12 kpc must be determined to better characterize the nature of the transition from inner to outer disk. We have initiated a survey of abundances of 20 open clusters in this region using spectroscopy obtained with the WIYN, KPNO 4m, CTIO 4m and Hobby-Eberly telescopes. Chemical abundances are determined for Fe, O, Na, and alpha-elements, among others. Results for the survey to date are presented here.

Long-term change in benthopelagic fish abundance in the abyssal northeast Pacific Ocean.

PubMed

Bailey, D M; Ruhl, H A; Smith, K L

2006-03-01

Food web structure, particularly the relative importance of bottom-up and top-down control of animal abundances, is poorly known for the Earth's largest habitats: the abyssal plains. A unique 15-yr time series of climate, productivity, particulate flux, and abundance of primary consumers (primarily echinoderms) and secondary consumers (fish) was examined to elucidate the response of trophic levels to temporal variation in one another. Towed camera sled deployments in the abyssal northeast Pacific (4100 m water depth) showed that annual mean numbers of the dominant fish genus (Coryphaenoides spp.) more than doubled over the period 1989-2004. Coryphaenoides spp. abundance was significantly correlated with total abundance of mobile epibenthic megafauna (echinoderms), with changes in fish abundance lagging behind changes in the echinoderms. Direct correlations between surface climate and fish abundances, and particulate organic carbon (POC) flux and fish abundances, were insignificant, which may be related to the varied response of the potential prey taxa to climate and POC flux. This study provides a rare opportunity to study the long-term dynamics of an unexploited marine fish population and suggests a dominant role for bottom-up control in this system.

Longer-term effects of selective thinning on carabid beetles and spiders in the Cascade Mountains of southern Oregon

USGS Publications Warehouse

Peck, R.; Niwa, C.G.

2005-01-01

Within late-successional forests of the Cascade Mountains of southern Oregon, abundances of carabid beetles (Carabidae) and spiders (Araneae) from pitfall traps were compared between stands thinned 16-41 years prior and nearby unthinned stands. Species richness of both taxa were moderate for coniferous forests of this region, with 12 carabid beetle species and >120 spider species collected. No differences in total abundance or species richness were found between stand types for carabid beetles, although abundances of four of the six most common species differed significantly. Pterostichus setosus, the most abundant species collected, was significantly more abundant in unthinned stands, while Omus cazieri, P. lama, and Carabus taedatus were more numerous in thinned stands. In contrast, both total spider abundance and species richness were significantly higher in thinned stands. Hunting spiders within the families Lycosidae and Gnaphosidae, and the funnel web-building Dictynidae were captured more often in thinned stands while sheet web spiders within Linyphiidae and Hahniidae were more abundant in unthinned stands. The forest floor within unthinned stands was structurally more diverse than in thinned stands, but this did not lead to greater overall abundance or diversity of either carabid beetles or spiders.

Comparison of meiofaunal abundance in two mangrove wetlands in Tong'an Bay, Xiamen, China

NASA Astrophysics Data System (ADS)

Zhou, Xiping; Cai, Lizhe; Fu, Sujing

2015-10-01

To compare meiofaunal community in the two mangrove wetlands in Tong'an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang'an mangrove wetlands in the bay. The results showed that the Ne/Co ratio (nematode to benthic copepod) and organic matter in Fenglin mangrove wetland were higher than those in Xiang'an mangrove wetland. The meiofaunal abundance in Fenglin mangrove was all lower than that in Xiang'an mangrove wetland in summer, autumn and spring, while the meiofaunal abundance in Fenglin mangrove was higher than that in Xiang'an mangrove wetland in winter. Two-way ANOVA results showed that the meiofaunal abundance and nematode abundance were significantly different between regions, seasons and region×season. With all the results in the present study, we confirmed that the positive response of meiofaunal and nematode abundance were only detected for medium organic matter contents according to the Xiang'an wetland's level, and that the distribution of meiofaunal abundance would be influenced by sand content. Higher copepod abundance and lower N/C value usually suggest better environmental quality.

Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria.

PubMed

Okogwu, Okechukwu I; Ugwumba, Alex O

2009-01-01

The physicochemical variables and cyanobacteria of Mid-Cross River, Nigeria, were studied in six stations between March 2005 and August 2006 to determine the relationship between water quality and cyanobacteria abundance. Canonical Correspondence Analysis (CCA) showed that biological oxygen demand (BOD), dissolved oxygen, pH, water velocity, width and depth were important environmental factors that influenced cyanobacteria abundance. Trace metals, phosphate and nitrate increased significantly from values of previous studies indicating increased eutrophication of the river but were weakly correlated with cyanobacteria abundance and could be scarcely regarded as regulating factors. A higher cyanobacteria abundance was recorded during the wet season in most of the sampled stations. The dominant cyanobacteria included Microcystis aeruginosa, Aphanizomenon flos-aquae, Oscillatoria limnetica and Anabaena spiroides. The toxins produced by these species could degrade water quality. The factors favouring cyanobacteria abundance were identified as increased pH, width and depth. Increase in cyanobacteria abundance was associated with reduction in dissolved oxygen and increase in BOD values.

Abundances of sulfur in the Milky Way Disk from Peimbert Type II planetary nebulae

NASA Astrophysics Data System (ADS)

Milingo, Jacquelynne Brenda

2000-08-01

Sulfur abundance gradients and heavy element ratios for the Milky Way Disk are constructed based upon newly acquired spectrophotometry of Type II planetary nebulae (PN). These spectra extend from 3600-9600 angstroms allowing us to use the [SIII] 9069 and 9532 angstrom lines to improve upon earlier sulfur abundance estimates. Considering a significant portion of sulfur in PN exists in the S(+2) ionization stage (and higher) this method should allow us to extrapolate more reliable total element abundance from ionic abundances. Given the progenitor mass and location of Type II PN (close to the Galactic disk), this sample of objects is free of nucleosynthetic self-contamination and thus their S abundances in particular are expected to reflect levels of these elements in the interstellar medium at the time of PN progenitor formation. These sulfur abundances provide constraints for studying various aspects of GCE such as massive star yields and the distribution of S across the Milky Way disk.

Prevalence of avian haemosporidian parasites is positively related to the abundance of host species at multiple sites within a region.

PubMed

Ellis, Vincenzo A; Medeiros, Matthew C I; Collins, Michael D; Sari, Eloisa H R; Coffey, Elyse D; Dickerson, Rebecca C; Lugarini, Camile; Stratford, Jeffrey A; Henry, Donata R; Merrill, Loren; Matthews, Alix E; Hanson, Alison A; Roberts, Jackson R; Joyce, Michael; Kunkel, Melanie R; Ricklefs, Robert E

2017-01-01

Parasite prevalence is thought to be positively related to host population density owing to enhanced contagion. However, the relationship between prevalence and local abundance of multiple host species is underexplored. We surveyed birds and their haemosporidian parasites (genera Plasmodium and Haemoproteus) at multiple sites across eastern North America to test whether the prevalence of these parasites in a host species at a particular site is related to that host's local abundance. Prevalence was positively related to host abundance within most sites, although the effect was stronger and more consistent for Plasmodium than for Haemoproteus. In contrast, prevalence was not related to variation in the abundance of most individual host species among sites across the region. These results suggest that parasite prevalence partly reflects the relative abundances of host species in local assemblages. However, three nonnative host species had low prevalence despite being relatively abundant at one site, as predicted by the enemy release hypothesis.

TEA: A Code Calculating Thermochemical Equilibrium Abundances

NASA Astrophysics Data System (ADS)

Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver

2016-07-01

We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows & Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.

TEA: A CODE CALCULATING THERMOCHEMICAL EQUILIBRIUM ABUNDANCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver, E-mail: jasmina@physics.ucf.edu

2016-07-01

We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature–pressure pairs. We tested the code against the method of Burrows and Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows and Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but withmore » higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.« less

Project VeSElkA: results of abundance analysis for HD 53929 and HD 63975

NASA Astrophysics Data System (ADS)

Ndiaye, M. L.; LeBlanc, F.; Khalack, V.

2018-03-01

Project VeSElkA (Vertical Stratification of Element Abundances) has been initiated with the aim to detect and study the vertical stratification of element abundances in the atmosphere of chemically peculiar stars. Abundance stratification occurs in hydrodynamically stable stellar atmospheres due to the migration of the elements caused by atomic diffusion. Two HgMn stars, HD 53929 and HD 63975 were selected from the VeSElkA sample and analysed with the aim to detect some abundance peculiarities employing the ZEEMAN2 code. We present the results of abundance analysis of HD 53929 and HD 63975 observed recently with the spectropolarimeter ESPaDOnS at Canada-France-Hawaii Telescope. Evidence of phosphorus vertical stratification was detected in the atmosphere of these two stars. In both cases, phosphorus abundance increases strongly towards the superficial layers. The strong overabundance of Mn found in stellar atmosphere of both stars confirms that they are HgMn type stars.

The abundances of the elements in sharp-lined early type stars

NASA Technical Reports Server (NTRS)

Adelman, Saul J.

1992-01-01

An International Ultraviolet Explorer (IUE) observing strategy that has yielded co-added spectra with enhanced S/N ratios for several A and B stars was established. New observations by Roby and Adelman using the same technique were added two new Hg-Mn stars into this sample. A long-term study of elemental abundances in this uniform, high-quality set of IUE spectra for 13 stars was begun. The first stages of this project are reported: abundances for N, Cr, Mn, Fe, Co, and Ni. The study of the Fe-peak elements show that our data set can provide accurate abundances and that abundances obtained from UV and optical spectra often are in good agreement. The groundwork for selfconsistent abundance analyses of more exotic elements in our long term project was provided.

The Abundance of Iron-Peak Elements and the Dust Composition in eta Carinae: Manganese

NASA Technical Reports Server (NTRS)

Bautista, M. A.; Melendez, M.; Hartman, H.; Gull, T. R.; Lodders, K.

2010-01-01

We study the chemical abundances of the Strontium Filament found in the ejecta of (eta) Carinae. In particular, we derive the abundances of iron-peak elements front spectra of their singly ionized ions present in the optical/IR spectra. In this paper we analyze the spectrum of Mn II using a new non-LTE model for this system. In constructing this models we carried out theoretical calculations of radiative transition rates and electron impact excitation rate coefficients. We find that relative to Ni the gas phase abundance ratio of Mn is roughly solar, similar to the Cr abundance but in contrast to the large enhancements in the abundances of Sc and Ti. NVe interpret this result as an indication of non-equilibrium condensation in the ejecta of (eta) Carinae.

Chemical Abundance Measurements of Ultra-Faint Dwarf Galaxies Discovered by the Dark Energy Survey

NASA Astrophysics Data System (ADS)

Nagasawa, Daniel; Marshall, Jennifer L.; Simon, Joshua D.; Hansen, Terese; Li, Ting; Bernstein, Rebecca; Balbinot, Eduardo; Drlica-Wagner, Alex; Pace, Andrew; Strigari, Louis; Pellegrino, Craig; DePoy, Darren L.; Suntzeff, Nicholas; Bechtol, Keith; Dark Energy Suvey

2018-01-01

We present chemical abundance analysis results derived from high-resolution spectroscopy of ultra-faint dwarfs discovered by the Dark Energy Survey. Ultra-faint dwarf galaxies preserve a fossil record of the chemical abundance patterns imprinted by the first stars in the Universe. High-resolution spectroscopic observations of member stars in several recently discovered Milky Way satellites reveal a range of abundance patterns among ultra-faint dwarfs suggesting that star formation processes in the early Universe were quite diverse. The chemical content provides a glimpse not only of the varied nucleosynthetic processes and chemical history of the dwarfs themselves, but also the environment in which they were formed. We present the chemical abundance analysis of these objects and discuss possible explanations for the observed abundance patterns.

Elemental abundance analyses with coadded DAO spectrograms. IV - Revision of previous analyses. V - The mercury-manganese stars Phi Herculis, 28 Herculis and HR 7664

NASA Technical Reports Server (NTRS)

Adelman, Saul J.

1988-01-01

Changes in chromium, manganese, and nickel abundances derived from singly ionized lines are incorporated into the elemental abundance of Adelman and Hill (1987) in order to provide more accurate gf values and damping constants for several atomic species. An improved agreement with the values from neutral lines of the same element is found. In the second part, the method is applied to an elemental abundance analysis of three mercury-manganese stars, and correlations are found between the derived abundances and the effective temperature.

A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars

NASA Technical Reports Server (NTRS)

Chaffee, F. H., Jr.; White, R. E.

1982-01-01

Observations of interstellar absorption in the resonance doublet 7664, 7698 A of neutral potassium toward 188 early-type stars at a spectral resolution of 8 km/s are reported. The 7664 A line is successfully separated from nearly coincident telluric O2 absorption for all but a few of the 165 stars for which K I absorption is detected, making possible an abundance analysis by the doublet ratio method. The relationships between the potassium abundances and other atomic abundances, the abundance of molecular hydrogen, and interstellar reddening are investigated.

The use (and misuse) of archaeological salmon data to infer historical abundance in North America with a focus on New England

Treesearch

Stephen F. Jane; Keith H. Nislow; Andrew R. Whiteley

2014-01-01

Information about historical animal or plant abundance often either explicitly or implicitly informs current conservation practice. If it can be shown that an organism was not historically abundant in a region, its conservation importance may be downgraded. In contrast to abundant archaeological support for historic importance of salmon in the Pacific Northwest,...

Seasonal abundance of soil arthropods in relation to meteorological and edaphic factors in the agroecosystems of Faisalabad, Punjab, Pakistan

NASA Astrophysics Data System (ADS)

Shakir, Muhammad Mussadiq; Ahmed, Sohail

2015-05-01

Soil arthropods are an important component of agroecosystems, contributing significantly to their biodiversity and functioning. However, seasonal patterns, population dynamics, and significant roles of these soil arthropods in improvement of soil structures and functions are influenced by many factors. The objective of the current study was to investigate soil arthropod abundance in relation to a blend of meteorological and edaphic factors and to find out the difference in abundance among various crops (sugarcane, cotton, wheat, alfalfa fodder, and citrus orchards). The arthropod sampling was done by pitfall traps and Tullgren extractions on fortnightly intervals. Soil temperature and relative humidity were noted on the field sites while analysis for soil pH, organic matter, and soil moisture contents were done in the laboratory. The rainfall data was obtained from an observatory. Results showed that significant differences were found in soil arthropod abundance across different sampling months and crops. Out of total 13,673 soil arthropods sampled, 38 % belonged to Collembola, followed by 15 % Hymenoptera, 15 % Acarina, 11 % Myriapods, 6 % Coleoptera, 5 % Orthoptera, and 5 % Araneae. Mean abundance per sample was highest in summer months as compared to winter. Overall abundance per sample was significantly different between all crops ( p < 0.05). Cluster analysis revealed four categories of soil arthropods according to abundance, i.e., highly abundant (Collembola, Acarina, Myripoda, Hymenoptera), moderately abundant (Orthoptera, Aranae, Coleoptera), least abundant (Dermaptera, Hemiptera, Diptera), and rare (Blattaria, Isoptera, Diplura, Lepidoptera). Soil temperature and soil organic matter showed significant positive correlation with abundance, while relative humidity was significantly negatively correlated. Soil moisture and soil pH showed no significant correlations while no correlation was found with total rainfall. PCA analysis revealed that soil surface arthropods were the major contributors of variation in overall abundance in extreme temperature months while microarthropods in low-temperature months. CCA analysis revealed the occurrence of different arthropod groups in correspondence with different abiotic variables. Results are discussed in view of position of these arthropods as useful indicators under changing environmental conditions impacting agroecosystems in the study area.

Microplitis demolitor bracovirus genome segments vary in abundance and are individually packaged in virions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beck, Markus H.; Inman, Ross B.; Strand, Michael R.

2007-03-01

Polydnaviruses (PDVs) are distinguished by their unique association with parasitoid wasps and their segmented, double-stranded (ds) DNA genomes that are non-equimolar in abundance. Relatively little is actually known, however, about genome packaging or segment abundance of these viruses. Here, we conducted electron microscopy (EM) and real-time polymerase chain reaction (PCR) studies to characterize packaging and segment abundance of Microplitis demolitor bracovirus (MdBV). Like other PDVs, MdBV replicates in the ovaries of females where virions accumulate to form a suspension called calyx fluid. Wasps then inject a quantity of calyx fluid when ovipositing into hosts. The MdBV genome consists of 15more » segments that range from 3.6 (segment A) to 34.3 kb (segment O). EM analysis indicated that MdBV virions contain a single nucleocapsid that encapsidates one circular DNA of variable size. We developed a semi-quantitative real-time PCR assay using SYBR Green I. This assay indicated that five (J, O, H, N and B) segments of the MdBV genome accounted for more than 60% of the viral DNAs in calyx fluid. Estimates of relative segment abundance using our real-time PCR assay were also very similar to DNA size distributions determined from micrographs. Analysis of parasitized Pseudoplusia includens larvae indicated that copy number of MdBV segments C, B and J varied between hosts but their relative abundance within a host was virtually identical to their abundance in calyx fluid. Among-tissue assays indicated that each viral segment was most abundant in hemocytes and least abundant in salivary glands. However, the relative abundance of each segment to one another was similar in all tissues. We also found no clear relationship between MdBV segment and transcript abundance in hemocytes and fat body.« less

Inferring invasive species abundance using removal data from management actions

USGS Publications Warehouse

Davis, Amy J.; Hooten, Mevin B.; Miller, Ryan S.; Farnsworth, Matthew L.; Lewis, Jesse S.; Moxcey, Michael; Pepin, Kim M.

2016-01-01

Evaluation of the progress of management programs for invasive species is crucial for demonstrating impacts to stakeholders and strategic planning of resource allocation. Estimates of abundance before and after management activities can serve as a useful metric of population management programs. However, many methods of estimating population size are too labor intensive and costly to implement, posing restrictive levels of burden on operational programs. Removal models are a reliable method for estimating abundance before and after management using data from the removal activities exclusively, thus requiring no work in addition to management. We developed a Bayesian hierarchical model to estimate abundance from removal data accounting for varying levels of effort, and used simulations to assess the conditions under which reliable population estimates are obtained. We applied this model to estimate site-specific abundance of an invasive species, feral swine (Sus scrofa), using removal data from aerial gunning in 59 site/time-frame combinations (480–19,600 acres) throughout Oklahoma and Texas, USA. Simulations showed that abundance estimates were generally accurate when effective removal rates (removal rate accounting for total effort) were above 0.40. However, when abundances were small (<50) the effective removal rate needed to accurately estimates abundances was considerably higher (0.70). Based on our post-validation method, 78% of our site/time frame estimates were accurate. To use this modeling framework it is important to have multiple removals (more than three) within a time frame during which demographic changes are minimized (i.e., a closed population; ≤3 months for feral swine). Our results show that the probability of accurately estimating abundance from this model improves with increased sampling effort (8+ flight hours across the 3-month window is best) and increased removal rate. Based on the inverse relationship between inaccurate abundances and inaccurate removal rates, we suggest auxiliary information that could be collected and included in the model as covariates (e.g., habitat effects, differences between pilots) to improve accuracy of removal rates and hence abundance estimates.

Critical metals in manganese nodules from the Cook Islands EEZ, abundances and distributions

USGS Publications Warehouse

Hein, James R.; Spinardi, Francesca; Okamoto, Nobuyuki; Mizell, Kira; Thorburn, Darryl; Tawake, Akuila

2015-01-01

Compiled data from a series of four cruises by the Japan International Cooperation Agency and the Mining agency of Japan from 1985 to 2000 were used to generate a map that defines the statistical distribution of nodule abundance throughout the EEZ, except the Manihiki Plateau. The abundance distribution map shows a belt of high nodule abundance (19–45 kg/m2) that starts in the southeast corner of the EEZ, runs northwest, and also bifurcates into a SW trending branch. Small, isolated areas contain abundances of nodules of up to 58 kg/m2. Six ~ 20,000 km2 areas of particularly high abundance were chosen to represent potential exploration areas, and maps for metal concentration were generated to visualize metal distribution and to extrapolate estimated metal tonnages within the six sites and the EEZ as a whole. Grades for Mn, Cu, and Ni are low in CIs nodules in areas of high abundance; however, Ti, Co, and REY show high contents where nodule abundances are high. Of the six areas identified to represent a range of metal contents, one at the northern end of the N-S abundance main belt optimizes the most metals and would yield the highest dry metric tons for Mn (61,002,292), Ni (1,247,834), Mo (186,166), V (356,247), W (30,215), and Zr (195,323). When compared with the Clarion–Clipperton Zone, the CIs nodules show higher nodule abundances (> 25 kg/m2 over ~ 123,844 km2), and are more enriched in the green-tech, high-tech, and energy metals Co, Ti, Te, Nb, REY, Pt, and Zr. The CIs EEZ shows a significant resource potential for these critical metals due to their high prices, high demand, and the high nodule abundance, which will allow for a smaller footprint for a 20-year mine site and therefore smaller environmental impact.

The elemental abundances (with uncertainties) of the most Earth-like planet

NASA Astrophysics Data System (ADS)

Wang, Haiyang S.; Lineweaver, Charles H.; Ireland, Trevor R.

2018-01-01

To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth's composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. First we compile, combine and renormalize a large set of heterogeneous literature values of the primitive mantle (PM) and of the core. We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth. Using estimates of the uncertainties in i) the density profiles, ii) the core-mantle boundary and iii) the inner core boundary, we employ standard error propagation to obtain a core mass fraction of 32.5 ± 0.3 wt%. Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances. Unlike previous efforts, the uncertainty on the core mass fraction is propagated to the uncertainties on the bulk Earth elemental abundances. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under various geochemical and geophysical assumptions.

Study of biological communities subject to imperfect detection: Bias and precision of community N-mixture abundance models in small-sample situations

USGS Publications Warehouse

Yamaura, Yuichi; Kery, Marc; Royle, Andy

2016-01-01

Community N-mixture abundance models for replicated counts provide a powerful and novel framework for drawing inferences related to species abundance within communities subject to imperfect detection. To assess the performance of these models, and to compare them to related community occupancy models in situations with marginal information, we used simulation to examine the effects of mean abundance (λ¯: 0.1, 0.5, 1, 5), detection probability (p¯: 0.1, 0.2, 0.5), and number of sampling sites (n site : 10, 20, 40) and visits (n visit : 2, 3, 4) on the bias and precision of species-level parameters (mean abundance and covariate effect) and a community-level parameter (species richness). Bias and imprecision of estimates decreased when any of the four variables (λ¯, p¯, n site , n visit ) increased. Detection probability p¯ was most important for the estimates of mean abundance, while λ¯ was most influential for covariate effect and species richness estimates. For all parameters, increasing n site was more beneficial than increasing n visit . Minimal conditions for obtaining adequate performance of community abundance models were n site  ≥ 20, p¯ ≥ 0.2, and λ¯ ≥ 0.5. At lower abundance, the performance of community abundance and community occupancy models as species richness estimators were comparable. We then used additive partitioning analysis to reveal that raw species counts can overestimate β diversity both of species richness and the Shannon index, while community abundance models yielded better estimates. Community N-mixture abundance models thus have great potential for use with community ecology or conservation applications provided that replicated counts are available.

History of Nebular Processing Traced by Silicate Stardust in IDPS

NASA Technical Reports Server (NTRS)

Messenger, Scott R.; Keller, L. P.; Nakamura-Messenger, K.

2010-01-01

Chondritic porous interplanetary dust particles (CP-IDPs) may be the best preserved remnants of primordial solar system materials, in part because they were not affected by parent body hydrothermal alteration. Their primitive characteristics include fine grained, unequilibrated, anhydrous mineralogy, enrichment in volatile elements, and abundant molecular cloud material and silicate stardust. However, while the majority of CP-IDP materials likely derived from the Solar System, their formation processes and provenance are poorly constrained. Stardust abundances provide a relative measure of the extent of processing that the Solar System starting materials has undergone in primitive materials. For example, among primitive meteorites silicate stardust abundances vary by over two orders of magnitude (less than 10-200 ppm). This range of abundances is ascribed to varying extents of aqueous processing in the meteorite parent bodies. The higher average silicate stardust abundances among CP-IDPs (greater than 375 ppm) are thus attributable to the lack of aqueous processing of these materials. Yet, silicate stardust abundances in IDPs also vary considerably. While the silicate stardust abundance in IDPs having anomalous N isotopic compositions was reported to be 375 ppm, the abundance in IDPs lacking N anomalies is less than 10 ppm. Furthermore, these values are significantly eclipsed among some IDPs with abundances ranging from 2,000 ppm to 10,000 ppm. Given that CP-IDPs have not been significantly affected by parent body processes, the difference in silicate stardust abundances among these IDPs must reflect varying extents of nebular processing. Here we present recent results of a systematic coordinated mineralogical/isotopic study of large cluster IDPs aimed at (1) characterizing the mineralogy of presolar silicates and (2) delineating the mineralogical and petrographic characteristics of IDPs with differing silicate stardust abundances. One of the goals of this study is to better understand the earliest stages of evolution of the Solar System starting materials.

Meteorological factors associated with abundance of airborne fungal spores over natural vegetation

NASA Astrophysics Data System (ADS)

Crandall, Sharifa G.; Gilbert, Gregory S.

2017-08-01

The abundance of airborne fungal spores in agricultural and urban settings increases with greater air temperature, relative humidity, or precipitation. The same meteorological factors that affect temporal patterns in spore abundance in managed environments also vary spatially across natural habitats in association with differences in vegetation structure. Here we investigated how temporal and spatial variation in aerial spore abundance is affected by abiotic (weather) and biotic (vegetation) factors as a foundation for predicting how fungi may respond to changes in weather and land-use patterns. We measured the phenology of airborne fungal spores across a mosaic of naturally occurring vegetation types at different time scales to describe (1) how spore abundance changes over time, (2) which local meteorological variables are good predictors for airborne spore density, and (3) whether spore abundance differs across vegetation types. Using an air volumetric vacuum sampler, we collected spore samples at 3-h intervals over a 120-h period in a mixed-evergreen forest and coastal prairie to measure diurnal, nocturnal, and total airborne spore abundance across vegetation types. Spore samples were also collected at weekly and monthly intervals in mixed-evergreen forest, redwood forest, and maritime chaparral vegetation types from 12 field sites across two years. We found greater airborne spore densities during the wetter winter months compared to the drier summer months. Mean total spore abundance in the mixed-evergreen forest was twice than in the coastal prairie, but there were no significant differences in total airborne spore abundance among mixed-evergreen forest, redwood forest, and maritime chaparral vegetation types. Weekly and monthly peaks in airborne spore abundance corresponded with rain events and peaks in soil moisture. Overall, temporal patterns in meteorological factors were much more important in determining airborne fungal spore abundance than the vegetation type. This suggests that overall patterns of fungal spore dynamics may be predictable across heterogeneous landscapes based on local weather patterns.

Modeling avian abundance from replicated counts using binomial mixture models

USGS Publications Warehouse

Kery, Marc; Royle, J. Andrew; Schmid, Hans

2005-01-01

Abundance estimation in ecology is usually accomplished by capture–recapture, removal, or distance sampling methods. These may be hard to implement at large spatial scales. In contrast, binomial mixture models enable abundance estimation without individual identification, based simply on temporally and spatially replicated counts. Here, we evaluate mixture models using data from the national breeding bird monitoring program in Switzerland, where some 250 1-km2 quadrats are surveyed using the territory mapping method three times during each breeding season. We chose eight species with contrasting distribution (wide–narrow), abundance (high–low), and detectability (easy–difficult). Abundance was modeled as a random effect with a Poisson or negative binomial distribution, with mean affected by forest cover, elevation, and route length. Detectability was a logit-linear function of survey date, survey date-by-elevation, and sampling effort (time per transect unit). Resulting covariate effects and parameter estimates were consistent with expectations. Detectability per territory (for three surveys) ranged from 0.66 to 0.94 (mean 0.84) for easy species, and from 0.16 to 0.83 (mean 0.53) for difficult species, depended on survey effort for two easy and all four difficult species, and changed seasonally for three easy and three difficult species. Abundance was positively related to route length in three high-abundance and one low-abundance (one easy and three difficult) species, and increased with forest cover in five forest species, decreased for two nonforest species, and was unaffected for a generalist species. Abundance estimates under the most parsimonious mixture models were between 1.1 and 8.9 (median 1.8) times greater than estimates based on territory mapping; hence, three surveys were insufficient to detect all territories for each species. We conclude that binomial mixture models are an important new approach for estimating abundance corrected for detectability when only repeated-count data are available. Future developments envisioned include estimation of trend, occupancy, and total regional abundance.

An intertebrate ecosystem engineer likely covered under the umbrella of sage-grouse conservation

USGS Publications Warehouse

Carlisle, Jason D.; Stewart, David R.; Chalfoun, Anna D.

2017-01-01

Conservation practitioners often rely on areas designed to protect species of greatest conservation priority to also conserve co-occurring species (i.e., the umbrella species concept). The extent to which vertebrate species may serve as suitable umbrellas for invertebrate species, however, has rarely been explored. Sage-grouse (Centrocercus spp.) have high conservation priority throughout much of the rangelands of western North America and are considered an umbrella species through which the conservation of entire rangeland ecosystems can be accomplished. Harvester ants are ecosystem engineers and play important roles in the maintenance and function of rangeland ecosystems. We compared indices of the abundance of western harvester ants (Pogonomyrmex occidentalis) and Greater Sage-Grouse (Centrocercus urophasianus) at 72 sites in central Wyoming, USA, in 2012. The abundance of harvester ant mounds was best predicted by a regression model that included a combination of local habitat characteristics and the abundance of sage-grouse. When controlling for habitat-related factors, areas with higher abundances of sage-grouse pellets (an index of sage-grouse abundance and/or habitat use) had higher abundances of ant mounds than areas with lower abundances of sage-grouse pellets. The causal mechanism underlying this positive relationship between sage-grouse and ant mound abundance at the fine scale could be indirect (e.g., both species prefer similar environmental conditions) or direct (e.g., sage-grouse prefer areas with a high abundance of ant mounds because ants are an important prey item during certain life stages). We observed no relationship between a broad-scale index of breeding sage-grouse density and the abundance of ant mounds. We suspect that consideration of the nonbreeding habitat of sage-grouse and finer-scale measures of sagegrouse abundance are critical to the utility of sage-grouse as an umbrella species for the conservation of harvester ants and their important role in rangeland ecosystems.

Modelling community dynamics based on species-level abundance models from detection/nondetection data

USGS Publications Warehouse

Yamaura, Yuichi; Royle, J. Andrew; Kuboi, Kouji; Tada, Tsuneo; Ikeno, Susumu; Makino, Shun'ichi

2011-01-01

1. In large-scale field surveys, a binary recording of each species' detection or nondetection has been increasingly adopted for its simplicity and low cost. Because of the importance of abundance in many studies, it is desirable to obtain inferences about abundance at species-, functional group-, and community-levels from such binary data. 2. We developed a novel hierarchical multi-species abundance model based on species-level detection/nondetection data. The model accounts for the existence of undetected species, and variability in abundance and detectability among species. Species-level detection/nondetection is linked to species- level abundance via a detection model that accommodates the expectation that probability of detection (at least one individuals is detected) increases with local abundance of the species. We applied this model to a 9-year dataset composed of the detection/nondetection of forest birds, at a single post-fire site (from 7 to 15 years after fire) in a montane area of central Japan. The model allocated undetected species into one of the predefined functional groups by assuming a prior distribution on individual group membership. 3. The results suggest that 15–20 species were missed in each year, and that species richness of communities and functional groups did not change with post-fire forest succession. Overall abundance of birds and abundance of functional groups tended to increase over time, although only in the winter, while decreases in detectabilities were observed in several species. 4. Synthesis and applications. Understanding and prediction of large-scale biodiversity dynamics partly hinge on how we can use data effectively. Our hierarchical model for detection/nondetection data estimates abundance in space/time at species-, functional group-, and community-levels while accounting for undetected individuals and species. It also permits comparison of multiple communities by many types of abundance-based diversity and similarity measures under imperfect detection.

Recombination Line versus Forbidden Line Abundances in Planetary Nebulae

NASA Astrophysics Data System (ADS)

Robertson-Tessi, Mark; Garnett, Donald R.

2005-04-01

Recombination lines (RLs) of C II, N II, and O II in planetary nebulae (PNs) have been found to give abundances that are much larger in some cases than abundances from collisionally excited forbidden lines (CELs). The origins of this abundance discrepancy are highly debated. We present new spectroscopic observations of O II and C II recombination lines for six planetary nebulae. With these data we compare the abundances derived from the optical recombination lines with those determined from collisionally excited lines. Combining our new data with published results on RLs in other PNs, we examine the discrepancy in abundances derived from RLs and CELs. We find that there is a wide range in the measured abundance discrepancy Δ(O+2)=logO+2(RL)-logO+2(CEL), ranging from approximately 0.1 dex (within the 1 σ measurement errors) up to 1.4 dex. This tends to rule out errors in the recombination coefficients as a source of the discrepancy. Most RLs yield similar abundances, with the notable exception of O II multiplet V15, known to arise primarily from dielectronic recombination, which gives abundances averaging 0.6 dex higher than other O II RLs. We compare Δ(O+2) against a variety of physical properties of the PNs to look for clues as to the mechanism responsible for the abundance discrepancy. The strongest correlations are found with the nebula diameter and the Balmer surface brightness; high surface brightness, compact PNs show small values of Δ(O+2), while large low surface brightness PNs show the largest discrepancies. An inverse correlation of Δ(O+2) with nebular density is also seen. A marginal correlation of Δ(O+2) is found with expansion velocity. No correlations are seen with electron temperature, He+2/He+, central star effective temperature and luminosity, stellar mass-loss rate, or nebular morphology. Similar results are found for carbon in comparing C II RL abundances with ultraviolet measurements of C III].

Rubidium and Lead Abundances in Giant Stars of the Globular Clusters M13 and NGC 6752

NASA Astrophysics Data System (ADS)

Yong, David; Aoki, Wako; Lambert, David L.; Paulson, Diane B.

2006-03-01

We present measurements of the neutron-capture elements Rb and Pb in five giant stars of the globular cluster NGC 6752 and Pb measurements in four giants of the globular cluster M13. The abundances were derived by comparing synthetic spectra with high-resolution, high signal-to-noise ratio spectra obtained using HDS on the Subaru telescope and MIKE on the Magellan telescope. The program stars span the range of the O-Al abundance variation. In NGC 6752, the mean abundances are [Rb/Fe]=-0.17+/-0.06 (σ=0.14), [Rb/Zr]=-0.12+/-0.06 (σ=0.13), and [Pb/Fe]=-0.17+/-0.04 (σ=0.08). In M13 the mean abundance is [Pb/Fe]=-0.28+/-0.03 (σ=0.06). Within the measurement uncertainties, we find no evidence for star-to-star variation for either Rb or Pb within these clusters. None of the abundance ratios [Rb/Fe], [Rb/Zr], or [Pb/Fe] are correlated with the Al abundance. NGC 6752 may have slightly lower abundances of [Rb/Fe] and [Rb/Zr] compared to the small sample of field stars at the same metallicity. For M13 and NGC 6752 the Pb abundances are in accord with predictions from a Galactic chemical evolution model. If metal-poor intermediate-mass asymptotic giant branch stars did produce the globular cluster abundance anomalies, then such stars do not synthesize significant quantities of Rb or Pb. Alternatively, if such stars do synthesize large amounts of Rb or Pb, then they are not responsible for the abundance anomalies seen in globular clusters. Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations made with the Magellan Clay Telescope at Las Campanas Observatory.

Wild Steelhead and introduced spring Chinook Salmon in the Wind River, Washington: Overlapping populations and interactions

USGS Publications Warehouse

Jezorek, I.G.; Connolly, P.J.

2010-01-01

We investigated interactions of introduced juvenile spring Chinook salmon Oncorhynchus tshawytscha with wild juvenile steelhead O. mykiss in the upper Wind River watershed (rkm 24.6 to rkm 43.8), Washington. Our objective was to determine if the presence of introduced spring Chinook salmon influenced populations of wild juvenile steelhead and if other biotic or abiotic factors influenced distribution and populations of these species. We snorkeled to assess distribution and abundance in one to six stream reaches per year during 2001 through 2007. Juvenile steelhead were found in each sampled reach each year, but juvenile Chinook salmon were not. The upstream extent of distribution of juvenile Chinook salmon varied from rkm 29.7 to 42.5. Our analyses suggest that juvenile Chinook salmon distribution was much influenced by flow during the spawning season. Low flow appeared to limit access of escaped adult Chinook salmon to upper stream reaches. Abundance of juvenile Chinook salmon was also influenced by base flow during the previous year, with base flow occurring post spawn in late August or early September. There were no relationships between juvenile Chinook salmon abundance and number of Chinook salmon spawners, magnitude of winter flow that might scour redds, or abundance of juvenile steelhead. Abundance of age-0 steelhead was influenced primarily by the number of steelhead spawners the previous year, and abundance of age-1 steelhead was influenced primarily by abundance of age-0 steelhead the previous year. Juvenile steelhead abundance did not show a relationship with base or peak flows, nor with number of escaped Chinook salmon adults during the previous year. We did not detect a negative influence of the relatively low abundance of progeny of escaped Chinook salmon on juvenile steelhead abundance. This low abundance of juvenile Chinook salmon was persistent throughout our study and is likely a result of hatchery management and habitat conditions. Should one or both change in the future, the potential for negative interactions with wild steelhead could change.

Abundance of large old trees in wood-pastures of Transylvania (Romania).

PubMed

Hartel, Tibor; Hanspach, Jan; Moga, Cosmin I; Holban, Lucian; Szapanyos, Árpád; Tamás, Réka; Hováth, Csaba; Réti, Kinga-Olga

2018-02-01

Wood-pastures are special types of agroforestry systems that integrate trees with livestock grazing. Wood pastures can be hotspots for large old tree abundance and have exceptional natural values; but they are declining all over Europe. While presence of large old trees in wood-pastures can provide arguments for their maintenance, actual data on their distribution and abundance are sparse. Our study is the first to survey large old trees in Eastern Europe over such a large area. We surveyed 97 wood-pastures in Transylvania (Romania) in order to (i) provide a descriptive overview of the large old tree abundance; and (ii) to explore the environmental determinants of the abundance and persistence of large old trees in wood-pastures. We identified 2520 large old trees belonging to 16 taxonomic groups. Oak was present in 66% of the wood-pastures, followed by beech (33%), hornbeam (24%) and pear (22%). For each of these four species we constructed a generalized linear model with quasi-Poisson error distribution to explain individual tree abundance. Oak trees were most abundant in large wood-pastures and in wood-pastures from the Saxon cultural region of Transylvania. Beech abundance related positively to elevation and to proximity of human settlements. Abundance of hornbeam was highest in large wood-pastures, in wood-pastures from the Saxon cultural region, and in places with high cover of adjacent forest and a low human population density. Large old pear trees were most abundant in large wood-pastures that were close to paved roads. The maintenance of large old trees in production landscapes is a challenge for science, policy and local people, but it also can serve as an impetus for integrating economic, ecological and social goals within a landscape. Copyright © 2017 Elsevier B.V. All rights reserved.

How Ants Drop Out: Ant Abundance on Tropical Mountains

PubMed Central

Longino, John T.; Branstetter, Michael G.; Colwell, Robert K.

2014-01-01

In tropical wet forests, ants are a large proportion of the animal biomass, but the factors determining abundance are not well understood. We characterized ant abundance in the litter layer of 41 mature wet forest sites spread throughout Central America (Chiapas, Guatemala, Honduras, Nicaragua, and Costa Rica) and examined the impact of elevation (as a proxy for temperature) and community species richness. Sites were intentionally chosen to minimize variation in precipitation and seasonality. From sea level to 1500 m ant abundance very gradually declined, community richness declined more rapidly than abundance, and the local frequency of the locally most common species increased. These results suggest that within this elevational zone, density compensation is acting, maintaining high ant abundance as richness declines. In contrast, in sites above 1500 m, ant abundance dropped abruptly to much lower levels. Among these high montane sites, community richness explained much more of the variation in abundance than elevation, and there was no evidence of density compensation. The relative stability of abundance below 1500 m may be caused by opposing effects of temperature on productivity and metabolism. Lower temperatures may decrease productivity and thus the amount of food available for consumers, but slower metabolisms of consumers may allow maintenance of higher biomass at lower resource supply rates. Ant communities at these lower elevations may be highly interactive, the result of continuous habitat presence over geological time. High montane sites may be ephemeral in geological time, resulting in non-interactive communities dominated by historical and stochastic processes. Abundance in these sites may be determined by the number of species that manage to colonize and/or avoid extinction on mountaintops. PMID:25098722

How ants drop out: ant abundance on tropical mountains.

PubMed

Longino, John T; Branstetter, Michael G; Colwell, Robert K

2014-01-01

In tropical wet forests, ants are a large proportion of the animal biomass, but the factors determining abundance are not well understood. We characterized ant abundance in the litter layer of 41 mature wet forest sites spread throughout Central America (Chiapas, Guatemala, Honduras, Nicaragua, and Costa Rica) and examined the impact of elevation (as a proxy for temperature) and community species richness. Sites were intentionally chosen to minimize variation in precipitation and seasonality. From sea level to 1500 m ant abundance very gradually declined, community richness declined more rapidly than abundance, and the local frequency of the locally most common species increased. These results suggest that within this elevational zone, density compensation is acting, maintaining high ant abundance as richness declines. In contrast, in sites above 1500 m, ant abundance dropped abruptly to much lower levels. Among these high montane sites, community richness explained much more of the variation in abundance than elevation, and there was no evidence of density compensation. The relative stability of abundance below 1500 m may be caused by opposing effects of temperature on productivity and metabolism. Lower temperatures may decrease productivity and thus the amount of food available for consumers, but slower metabolisms of consumers may allow maintenance of higher biomass at lower resource supply rates. Ant communities at these lower elevations may be highly interactive, the result of continuous habitat presence over geological time. High montane sites may be ephemeral in geological time, resulting in non-interactive communities dominated by historical and stochastic processes. Abundance in these sites may be determined by the number of species that manage to colonize and/or avoid extinction on mountaintops.

High chemical abundances in stripped Virgo spiral galaxies

NASA Technical Reports Server (NTRS)

Skillman, E. D.; Kennicutt, R. C.; Shields, G. A.

1993-01-01

Based on a comparison of the oxygen abundances in H 2 regions in field and Virgo cluster late type spiral galaxies, Shields, Skillman, & Kennicutt (1991) suggested that the highly stripped spiral galaxies in the Virgo cluster have systematically higher abundances than comparable field galaxies. In April 1991 and May 1992 we used the blue channel spectrograph on the MMT to obtain new observations of 30 H 2 regions in Virgo spiral galaxies. These spectra cover the wavelength range from (O II) lambda 3727 to (S II) lambda 6731. We now have observed at least 4 H II regions in 9 spiral galaxies in the Virgo cluster. Combining (O II) and (O III) line strengths, we calculate the H II region oxygen abundances based on the empirical calibration of Edmunds & Pagel (1984). These observations show: (1) The stripped, low luminosity Virgo spirals (N4689, N4571) truly have abundances characteristic of much more luminous field spirals; (2) Virgo spirals which show no evidence of stripping (N4651, N4713) have abundances comparable to field galaxies; and (3) Evidence for transition galaxies (e.g., N4254, N4321), with marginally stripped disks and marginal abundance enhancements. The new observations presented here confirm the validity of the oxygen over-abundances in the stripped Virgo spirals. Shields et al. (1991) discussed two different mechanisms for producing the higher abundances in the disks of stripped galaxies in Virgo. The first is the supression of infall of near-primordial material, the second is the suppression of radial inflow of metal-poor gas. Distinguishing between the two cases will require more observations of the Virgo cluster spirals and a better understanding of which parameters determine the variation of abundance with radius in field spirals (cf., Garnett & Shields 1987).

A search for stars of very low metal abundance. VI. Detailed abundances of 313 metal-poor stars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roederer, Ian U.; Preston, George W.; Thompson, Ian B.

2014-06-01

We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10 yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coudé Spectrograph on the Harlan J. Smith Telescope atmore » McDonald Observatory, and the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by ≈0.25 dex for red giants and ≈0.04 dex for subgiants. Our sample contains 19 stars with [Fe/H] ≤–3.5, 84 stars with [Fe/H] ≤–3.0, and 210 stars with [Fe/H] ≤–2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H] ≤–2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.« less

Modeling CO, CO2, and H2O Ice Abundances in the Envelopes of Young Stellar Objects in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Pauly, Tyler; Garrod, Robin T.

2018-02-01

Massive young stellar objects (MYSOs) in the Magellanic Clouds show infrared absorption features corresponding to significant abundances of CO, CO2, and H2O ice along the line of sight, with the relative abundances of these ices differing between the Magellanic Clouds and the Milky Way. CO ice is not detected toward sources in the Small Magellanic Cloud, and upper limits put its relative abundance well below sources in the Large Magellanic Cloud and the Milky Way. We use our gas-grain chemical code MAGICKAL, with multiple grain sizes and grain temperatures, and further expand it with a treatment for increased interstellar radiation field intensity to model the elevated dust temperatures observed in the MCs. We also adjust the elemental abundances used in the chemical models, guided by observations of H II regions in these metal-poor satellite galaxies. With a grid of models, we are able to reproduce the relative ice fractions observed in MC MYSOs, indicating that metal depletion and elevated grain temperature are important drivers of the MYSO envelope ice composition. Magellanic Cloud elemental abundances have a subgalactic C/O ratio, increasing H2O ice abundances relative to the other ices; elevated grain temperatures favor CO2 production over H2O and CO. The observed shortfall in CO in the Small Magellanic Cloud can be explained by a combination of reduced carbon abundance and increased grain temperatures. The models indicate that a large variation in radiation field strength is required to match the range of observed LMC abundances. CH3OH abundance is found to be enhanced in low-metallicity models, providing seed material for complex organic molecule formation in the Magellanic Clouds.

Using counts to simultaneously estimate abundance and detection probabilities in a salamander community

USGS Publications Warehouse

Dodd, C.K.; Dorazio, R.M.

2004-01-01

A critical variable in both ecological and conservation field studies is determining how many individuals of a species are present within a defined sampling area. Labor intensive techniques such as capture-mark-recapture and removal sampling may provide estimates of abundance, but there are many logistical constraints to their widespread application. Many studies on terrestrial and aquatic salamanders use counts as an index of abundance, assuming that detection remains constant while sampling. If this constancy is violated, determination of detection probabilities is critical to the accurate estimation of abundance. Recently, a model was developed that provides a statistical approach that allows abundance and detection to be estimated simultaneously from spatially and temporally replicated counts. We adapted this model to estimate these parameters for salamanders sampled over a six vear period in area-constrained plots in Great Smoky Mountains National Park. Estimates of salamander abundance varied among years, but annual changes in abundance did not vary uniformly among species. Except for one species, abundance estimates were not correlated with site covariates (elevation/soil and water pH, conductivity, air and water temperature). The uncertainty in the estimates was so large as to make correlations ineffectual in predicting which covariates might influence abundance. Detection probabilities also varied among species and sometimes among years for the six species examined. We found such a high degree of variation in our counts and in estimates of detection among species, sites, and years as to cast doubt upon the appropriateness of using count data to monitor population trends using a small number of area-constrained survey plots. Still, the model provided reasonable estimates of abundance that could make it useful in estimating population size from count surveys.

Consideraciones para la estimacion de abundancia de poblaciones de mamiferos. [Considerations for the estimation of abundance of mammal populations.

USGS Publications Warehouse

Walker, R.S.; Novare, A.J.; Nichols, J.D.

2000-01-01

Estimation of abundance of mammal populations is essential for monitoring programs and for many ecological investigations. The first step for any study of variation in mammal abundance over space or time is to define the objectives of the study and how and why abundance data are to be used. The data used to estimate abundance are count statistics in the form of counts of animals or their signs. There are two major sources of uncertainty that must be considered in the design of the study: spatial variation and the relationship between abundance and the count statistic. Spatial variation in the distribution of animals or signs may be taken into account with appropriate spatial sampling. Count statistics may be viewed as random variables, with the expected value of the count statistic equal to the true abundance of the population multiplied by a coefficient p. With direct counts, p represents the probability of detection or capture of individuals, and with indirect counts it represents the rate of production of the signs as well as their probability of detection. Comparisons of abundance using count statistics from different times or places assume that the p are the same for all times or places being compared (p= pi). In spite of considerable evidence that this assumption rarely holds true, it is commonly made in studies of mammal abundance, as when the minimum number alive or indices based on sign counts are used to compare abundance in different habitats or times. Alternatives to relying on this assumption are to calibrate the index used by testing the assumption of p= pi, or to incorporate the estimation of p into the study design.

Oxygen abundance distributions in six late-type galaxies based on SALT spectra of H II regions

NASA Astrophysics Data System (ADS)

Zinchenko, I. A.; Kniazev, A. Y.; Grebel, E. K.; Pilyugin, L. S.

2015-10-01

Spectra of 34 H ii regions in the late-type galaxies NGC 1087, NGC 2967, NGC 3023, NGC 4030, NGC 4123, and NGC 4517A were observed with the South African Large Telescope (SALT). In all 34 H ii regions, oxygen abundances were determined through the "counterpart" method (C method). Additionally, in two H ii regions in which we detected auroral lines, we measured oxygen abundances with the classic Te method. We also estimated the abundances in our H ii regions using the O3N2 and N2 calibrations and compared those with the C-based abundances. With these data, we examined the radial abundance distributions in the disks of our target galaxies. We derived surface-brightness profiles and other characteristics of the disks (the surface brightness at the disk center and the disk scale length) in three photometric bands for each galaxy using publicly available photometric imaging data. The radial distributions of the oxygen abundances predicted by the relation between abundance and disk surface brightness in the W1 band obtained for spiral galaxies in our previous study are close to the radial distributions of the oxygen abundances determined from the analysis of the emission line spectra for four galaxies where this relation is applicable. Hence, when the surface-brightness profile of a late-type galaxy is known, this parametric relation can be used to estimate the likely present-day oxygen abundance in the disk of the galaxy. Based on observations made with the Southern African Large Telescope, programs 2012-1-RSA_OTH-001, 2012-2-RSA_OTH-003 and 2013-1-RSA_OTH-005.

The Antarctic environment and its effect upon the total carbon and sulfur abundances in recovered meteorites

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Andrawes, F. F.

1980-01-01

Total carbon and sulfur abundances have been measured for 25 meteorites recovered from the Allan Hills area of Antarctica. The majority (greater than 67%) of the meteorites analyzed do not contain enriched carbon abundances resulting from weathering processes. The presence of secondary carbonates in samples which give no apparent evidence of weathering was noted during pyrolysis experiments, despite the 'normal' total carbon abundances. In selected cases, the surfaces of weathered samples may contain up to a factor of two greater carbon content than the interior. Variations in carbon abundances may reflect the degree of weathering and the amount of secondary minerals present. One of the surprises of this study is that the majority of the Antarctic meteorites studied do not exhibit total carbon and sulfur abundances outside the ranges previously observed for falls.

Light element geochemistry of the Apollo 16 site

NASA Technical Reports Server (NTRS)

Kerridge, J. F.; Kaplan, I. R.; Petrowski, C.; Chang, S.

1975-01-01

The abundance and isotopic composition of carbon, sulfur, and nitrogen, the abundance of helium and hydrogen, and the content of metallic iron are reported for lunar surface samples from the Apollo 16 landing site at Cayley-Descartes. The light elements show marked interstation variability at the site. The abundances in soils of C, N, He, and H are apparently controlled mainly by exposure to the solar wind, through implantation or stripping processes. Carbon abundances (but not observed isotopic distributions) are compatible with a model in which equilibrium is established after 10,000-100,000 yr between solar wind input and loss by proton stripping. Sulfur abundances in soils are apparently controlled by abundances in local country rocks, but the lunar S cycle is quite complex. A metallic iron component may have originated by solar wind reduction of lunar Fe(2+).

Baleen whales and their prey in a coastal environment

USGS Publications Warehouse

Piatt, John F.; Methven, David A.; Burger, Alan E.; McLagan, Ruth L.; Mercer, Vicki; Creelman, Elizabeth

1989-01-01

Patterns of abundance of humpback (Megaptera novaeangliae), fin (Balaenoptera physalus), and minke (Balaenoptera acutorostrata) whales are described in relation to the abundance of their primary prey, capelin (Mallotus villosus), during 1982–1985 at Witless Bay, Newfoundland. The abundance ratio of the three whale species was 10:1:3.5, respectively. Abundance of all whale species was strongly correlated with abundance of capelin through each season and between years. Capelin abundance accounted for 63% of the variation in whale numbers in 1983 and 1984, while environmental parameters (e.g., water temperatures) accounted for little variance. The amount of capelin consumed by whales was small (< 2%) compared with the amount available. All three species overlapped temporally at Witless Bay, but spatial overlap was reduced as fins occurred primarily offshore, minkes primarily inshore, and humpbacks in bay habitats of intermediate depth.

Improving removal-based estimates of abundance by sampling a population of spatially distinct subpopulations

USGS Publications Warehouse

Dorazio, R.M.; Jelks, H.L.; Jordan, F.

2005-01-01

 A statistical modeling framework is described for estimating the abundances of spatially distinct subpopulations of animals surveyed using removal sampling. To illustrate this framework, hierarchical models are developed using the Poisson and negative-binomial distributions to model variation in abundance among subpopulations and using the beta distribution to model variation in capture probabilities. These models are fitted to the removal counts observed in a survey of a federally endangered fish species. The resulting estimates of abundance have similar or better precision than those computed using the conventional approach of analyzing the removal counts of each subpopulation separately. Extension of the hierarchical models to include spatial covariates of abundance is straightforward and may be used to identify important features of an animal's habitat or to predict the abundance of animals at unsampled locations.

The Abundance and Distribution of Presolar Materials in Cluster IDPS

NASA Technical Reports Server (NTRS)

Messenger, Scott; Keller, Lindsay; Nakamura-Messenger, Keiko; Ito, Motoo

2007-01-01

Presolar grains and remnants of interstellar organic compounds occur in a wide range of primitive solar system materials, including meteorites, interplanetary dust particles (IDPs), and comet Wild-2 samples. Among the most abundant presolar phases are silicate stardust grains and molecular cloud material. However, these materials have also been susceptible to destruction and alteration during parent body and nebular processing. In addition to their importance as direct samples of remote and ancient astrophysical environments, presolar materials thus provide a measure of how well different primitive bodies have preserved the original solar system starting materials. The matrix normalized abundances of presolar silicate grains in meteorites range from 20 ppm in Semarkona and Bishunpur to 170 ppm for Acfer 094. The lower abundances of presolar silicates in Bishunpur and Semarkona has been ascribed to the destruction of presolar silicates during aqueous processes. Presolar silicates appear to be significantly more abundant in anhydrous IDPs, possibly because these materials did not experience parent body hydrothermal alteration. Among IDPs the estimated abundances of presolar silicates vary by more than an order of magnitude, from 480 to 5500 ppm. The wide disparity in the abundances of presolar silicates of IDPs may be a consequence of the relatively small total area analyzed in those studies and the fine grain sizes of the IDPs. Alternatively, there may be a wide range in presolar silicate abundances between different IDPs. This view is supported by the observation that 15N-rich IDPs have higher presolar silicate abundances than those with isotopically normal N.

Host trait combinations drive abundance and canopy distribution of atmospheric bromeliad assemblages

PubMed Central

Chaves, Cleber Juliano Neves; Dyonisio, Júlio César; Rossatto, Davi Rodrigo

2016-01-01

Epiphytes are strongly dependent on the conditions created by their host's traits and a certain degree of specificity is expected between them, even if these species are largely abundant in a series of tree hosts of a given environment, as in the case of atmospheric bromeliads. Despite their considerable abundance in these environments, we hypothesize that stochasticity alone cannot explain the presence and abundance of atmospheric bromeliads on host trees, since host traits could have a greater influence on the establishment of these bromeliads. We used secondary and reforested seasonal forests and three distinct silvicultures to test whether species richness, phylogenetic diversity and functional diversity of trees can predict the differential presence, abundance and distribution of atmospheric bromeliads on hosts. We compared the observed parameters of their assemblage with null models and performed successive variance hierarchic partitions of abundance and distribution of the assemblage to detect the influence of multiple traits of the tree hosts. Our results do not indicate direct relationships between the abundance of atmospheric bromeliads and phylogenetic or functional diversity of trees, but instead indicate that bromeliads occurred on fewer tree species than expected by chance. We distinguished functional tree patterns that can improve or reduce the abundance of atmospheric bromeliads, and change their distribution on branches and trunk. While individual tree traits are related to increased abundance, species traits are related to the canopy distribution of atmospheric bromeliad assemblages. A balance among these tree functional patterns drives the atmospheric bromeliad assemblage of the forest patches. PMID:26888951

Coronae of Stars with Supersolar Elemental Abundances

NASA Technical Reports Server (NTRS)

Peretz, Uria; Behar, Ehud; Drake, Stephen A.

2015-01-01

Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the first ionization potential (FIP). This study focuses on the coronal composition of stars with supersolar photospheric abundances. We present the coronal abundances of six such stars: 11 LMi, iota Hor, HR 7291, tau Boo, and alpha Cen A and B. These stars all have high-statistics X-ray spectra, three of which are presented for the first time. The abundances we measured were obtained using the line-resolved spectra of the Reflection Grating Spectrometer (RGS) in conjunction with the higher throughput EPIC-pn camera spectra onboard the XMM-Newton observatory. A collisionally ionized plasma model with two or three temperature components is found to represent the spectra well. All elements are found to be consistently depleted in the coronae compared to their respective photospheres. For 11 LMi and tau Boo no FIP effect is present, while iota Hor, HR 7291, and alpha Cen A and B show a clear FIP trend. These conclusions hold whether the comparison is made with solar abundances or the individual stellar abundances. Unlike the solar corona, where low-FIP elements are enriched, in these stars the FIP effect is consistently due to a depletion of high-FIP elements with respect to actual photospheric abundances. A comparison with solar (instead of stellar) abundances yields the same fractionation trend as on the Sun. In both cases, a similar FIP bias is inferred, but different fractionation mechanisms need to be invoked.

Factors responsible for Ixodes ricinus nymph abundance: Are soil features indicators of tick abundance in a French region where Lyme borreliosis is endemic?

PubMed

Goldstein, Valérie; Boulanger, Nathalie; Schwartz, Dominique; George, Jean-Claude; Ertlen, Damien; Zilliox, Laurence; Schaeffer, Mickaël; Jaulhac, Benoît

2018-05-01

In Europe, the hard tick Ixodes ricinus (Acari: Ixodidae) is the main vector of Lyme borreliosis spirochetes (Borrelia burgdorferi sensu lato group). A field study was conducted to evaluate the abundance of Ixodes nymphs in the French region of Alsace, where Lyme borreliosis is endemic, and to determine whether environmental factors such as soil moisture and composition may be associated with nymph abundance. In the ten sites studied, ticks were collected by drag sampling from March to October in 2013 and 2014. Temperature, relative humidity, saturation deficit, soil pH, humus composition and type of vegetation were recorded at each site. The abundance of I. ricinus was highly variable from one site to another. Inter-annual variations were also observed, since the nymph abundance were higher in 2013 than in 2014. This study shows that humus type can be indicative of nymph abundance. Three types of humus were observed: (1) moder, (2) mull, and (3) mull-moder humus. One of them, moder humus, which is characterized by a thick layer of fragmented leaves, was found in multivariate analyses to be strongly associated with the nymph abundance. This study demonstrates that factors such as saturation deficit do not suffice to explain the differences in nymph abundance among sites. The composition of the soil and especially the type of humus should also be taken into consideration when assessing acarological risk. Copyright © 2018 Elsevier GmbH. All rights reserved.

Waste rice for waterfowl in the Mississippi Alluvial Valley

USGS Publications Warehouse

Stafford, J.D.; Kaminski, R.M.; Reinecke, K.J.; Manley, S.W.

2006-01-01

Flooded rice fields are important foraging habitats for waterfowl in the lower Mississippi Alluvial Valley (MAV). Waste rice previously was abundant in late autumn (140?492 kg/ha), but early planting and harvest dates in recent years may have increased losses of waste rice during autumn before waterfowl arrive. Research in Mississippi rice fields revealed waste-rice abundance decreased 79?99% during autumns 1995?1996. To determine if this trend existed throughout the MAV, we used multistage sampling (MSS) to estimate waste-rice abundance during September?December 2000?2002. Averaged over years, mean abundance of waste rice decreased 71% between harvest ((x) over bar = 271.0 kg/ha, CV = 13% n = 3 years) and late autumn ( (x) over bar = 78.4 kg/ha, CV = 15% n = 3). Among 15 models formulated to explain variation in rice abundance among fields and across years, the best model indicated abundance of waste rice in late autumn differed between harvester types (i.e., conventional > stripper header) and was positively related to initial waste-rice abundance after harvest. Because abundance of waste rice in late autumn was less than previous estimates in all 3 years, we concluded that waterfowl conservationists have overestimated carrying capacity of rice fields for wintering waterfowl by 52?83% and recommend 325 duck-use days/ha (DUDs) as a revised estimate. We suggest monitoring advances in rice harvest dates to determine when new surveys are warranted and recommend increased management of moist-soil wetlands to compensate for decreased rice abundance.

Number of hummingbird visits determines flower mite abundance on hummingbird feeders.

PubMed

Márquez-Luna, Ubaldo; Vázquez González, María Magdalena; Castellanos, Ignacio; Ortiz-Pulido, Raúl

2016-08-01

Members of several genera of mites from the family Melicharidae (Mesostigmata) use hummingbirds as transport host to move from flower to flower, where they feed on pollen and nectar. The factors that influence hummingbird flower mite abundance on host plant flowers are not currently known. Here we tested whether hummingbird flower mite abundance on an artificial nectar source is determined by number of hummingbird visits, nectar energy content or species richness of visiting hummingbirds. We conducted experiments employing hummingbird feeders with sucrose solutions of low, medium, and high energy concentrations, placed in a xeric shrubland. In the first experiment, we recorded the number of visiting hummingbirds and the number of visiting hummingbird species, as well as the abundance of hummingbird flower mites on each feeder. Feeders with the highest sucrose concentration had the most hummingbird visits and the highest flower mite abundances; however, there was no significant effect of hummingbird species richness on mite abundance. In the second experiment, we recorded flower mite abundance on feeders after we standardized the number of hummingbird visits to them. Abundance of flower mites did not differ significantly between feeders when we controlled for hummingbird visits. Our results suggest that nectar energy concentration determines hummingbird visits, which in turn determines flower mite abundance in our feeders. Our results do not support the hypothesis that mites descend from hummingbird nostrils more on richer nectar sources; however, it does not preclude the possibility that flower mites select for nectar concentration at other spatial and temporal scales.

Silicon to iron abundances in solar cosmic rays and in the sun

NASA Technical Reports Server (NTRS)

Vahia, M. N.; Biswas, S.; Durgaprasad, N.

1985-01-01

Differential spectra of even charged nuclei between Si and Fe in the August 4, 1972 event were made in the energy region of 10 to 40 MeV/n-1 using rocket borne plastic detectors. The resulting relative abundances of elements and low energy enhancements are obtained and compared with spectroscopically determined photospheric abundances. The implications of the relative abundances on the acceleration mechanisms is discussed.

Implications of Abundant Gas and Oil for Climate Forcing

NASA Astrophysics Data System (ADS)

Edmonds, J.

2015-12-01

Perhaps the most important development in the field of energy over the past decade has been the advent of technologies that enable the production of larger volumes of natural gas and oil at lower cost. The availability of more abundant gas and oil is reshaping the global energy system, with implications for both evolving emissions of CO2 and other climate forcers. More abundant gas and oil will also transform the character of greenhouse gas emissions mitigation. We review recent findings regarding the impact of abundant gas and oil for climate forcing and the challenge of emissions mitigation. We find strong evidence that, absent policies to limits its penetration against renewable energy, abundant gas has little observable impact on CO2 emissions, and tends to increase overall climate forcing, though the latter finding is subject to substantial uncertainty. The presence of abundant gas also affects emissions mitigation. There is relatively little literature exploring the implication of expanded gas availability on the difficulty in meeting emissions mitigation goals. However, preliminary results indicate that on global scales abundant gas does not substantially affect the cost of emissions mitigation, even though natural gas could have an expanded role in emissions mitigation scenarios as compared with scenarios in which natural gas is less abundant.

Model reduction for stochastic chemical systems with abundant species.

PubMed

Smith, Stephen; Cianci, Claudia; Grima, Ramon

2015-12-07

Biochemical processes typically involve many chemical species, some in abundance and some in low molecule numbers. We first identify the rate constant limits under which the concentrations of a given set of species will tend to infinity (the abundant species) while the concentrations of all other species remains constant (the non-abundant species). Subsequently, we prove that, in this limit, the fluctuations in the molecule numbers of non-abundant species are accurately described by a hybrid stochastic description consisting of a chemical master equation coupled to deterministic rate equations. This is a reduced description when compared to the conventional chemical master equation which describes the fluctuations in both abundant and non-abundant species. We show that the reduced master equation can be solved exactly for a number of biochemical networks involving gene expression and enzyme catalysis, whose conventional chemical master equation description is analytically impenetrable. We use the linear noise approximation to obtain approximate expressions for the difference between the variance of fluctuations in the non-abundant species as predicted by the hybrid approach and by the conventional chemical master equation. Furthermore, we show that surprisingly, irrespective of any separation in the mean molecule numbers of various species, the conventional and hybrid master equations exactly agree for a class of chemical systems.

Estimating Lion Abundance using N-mixture Models for Social Species

PubMed Central

Belant, Jerrold L.; Bled, Florent; Wilton, Clay M.; Fyumagwa, Robert; Mwampeta, Stanslaus B.; Beyer, Dean E.

2016-01-01

Declining populations of large carnivores worldwide, and the complexities of managing human-carnivore conflicts, require accurate population estimates of large carnivores to promote their long-term persistence through well-informed management We used N-mixture models to estimate lion (Panthera leo) abundance from call-in and track surveys in southeastern Serengeti National Park, Tanzania. Because of potential habituation to broadcasted calls and social behavior, we developed a hierarchical observation process within the N-mixture model conditioning lion detectability on their group response to call-ins and individual detection probabilities. We estimated 270 lions (95% credible interval = 170–551) using call-ins but were unable to estimate lion abundance from track data. We found a weak negative relationship between predicted track density and predicted lion abundance from the call-in surveys. Luminosity was negatively correlated with individual detection probability during call-in surveys. Lion abundance and track density were influenced by landcover, but direction of the corresponding effects were undetermined. N-mixture models allowed us to incorporate multiple parameters (e.g., landcover, luminosity, observer effect) influencing lion abundance and probability of detection directly into abundance estimates. We suggest that N-mixture models employing a hierarchical observation process can be used to estimate abundance of other social, herding, and grouping species. PMID:27786283

Occurrence and abundance of antibiotic resistance genes in agricultural soil receiving dairy manure.

PubMed

McKinney, Chad W; Dungan, Robert S; Moore, Amber; Leytem, April B

2018-03-01

Animal manures are commonly used to enhance soil fertility, but there are growing concerns over the impact of this practice on the development and dissemination of antibiotic resistance. The aim of this field study was to determine the effect of annual dairy manure applications on the occurrence and abundance of antibiotic resistance genes (ARGs) in an agricultural soil during four years of crop production. Treatments included (i) control (no fertilizer or manure), (ii) inorganic fertilizer and (iii) dairy manure at three application rates. Quantitative PCR was used to determine absolute (per g dry soil) and relative (per 16S rRNA gene) abundances of ARGs in DNA extracted from soils. Six ARGs and one class 1 integron were targeted. This study found that (i) manure application increases ARG abundances above background soil levels; (ii) the higher the manure application rate, the higher the ARG abundance in soil; (iii) the amount of manure applied is more important than reoccurring annual applications of the same amount of manure; (iv) absolute abundance and occurrence of ARGs decreases with increasing soil depth, but relative abundances remained constant. This study demonstrated that dairy manure applications to soil significantly increase the abundance of clinically relevant ARGs when compared to control and inorganic fertilized plots.

Model reduction for stochastic chemical systems with abundant species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Stephen; Cianci, Claudia; Grima, Ramon

2015-12-07

Biochemical processes typically involve many chemical species, some in abundance and some in low molecule numbers. We first identify the rate constant limits under which the concentrations of a given set of species will tend to infinity (the abundant species) while the concentrations of all other species remains constant (the non-abundant species). Subsequently, we prove that, in this limit, the fluctuations in the molecule numbers of non-abundant species are accurately described by a hybrid stochastic description consisting of a chemical master equation coupled to deterministic rate equations. This is a reduced description when compared to the conventional chemical master equationmore » which describes the fluctuations in both abundant and non-abundant species. We show that the reduced master equation can be solved exactly for a number of biochemical networks involving gene expression and enzyme catalysis, whose conventional chemical master equation description is analytically impenetrable. We use the linear noise approximation to obtain approximate expressions for the difference between the variance of fluctuations in the non-abundant species as predicted by the hybrid approach and by the conventional chemical master equation. Furthermore, we show that surprisingly, irrespective of any separation in the mean molecule numbers of various species, the conventional and hybrid master equations exactly agree for a class of chemical systems.« less

Estimating Lion Abundance using N-mixture Models for Social Species.

PubMed

Belant, Jerrold L; Bled, Florent; Wilton, Clay M; Fyumagwa, Robert; Mwampeta, Stanslaus B; Beyer, Dean E

2016-10-27

Declining populations of large carnivores worldwide, and the complexities of managing human-carnivore conflicts, require accurate population estimates of large carnivores to promote their long-term persistence through well-informed management We used N-mixture models to estimate lion (Panthera leo) abundance from call-in and track surveys in southeastern Serengeti National Park, Tanzania. Because of potential habituation to broadcasted calls and social behavior, we developed a hierarchical observation process within the N-mixture model conditioning lion detectability on their group response to call-ins and individual detection probabilities. We estimated 270 lions (95% credible interval = 170-551) using call-ins but were unable to estimate lion abundance from track data. We found a weak negative relationship between predicted track density and predicted lion abundance from the call-in surveys. Luminosity was negatively correlated with individual detection probability during call-in surveys. Lion abundance and track density were influenced by landcover, but direction of the corresponding effects were undetermined. N-mixture models allowed us to incorporate multiple parameters (e.g., landcover, luminosity, observer effect) influencing lion abundance and probability of detection directly into abundance estimates. We suggest that N-mixture models employing a hierarchical observation process can be used to estimate abundance of other social, herding, and grouping species.

Bayesian change point analysis of abundance trends for pelagic fishes in the upper San Francisco Estuary.

PubMed

Thomson, James R; Kimmerer, Wim J; Brown, Larry R; Newman, Ken B; Mac Nally, Ralph; Bennett, William A; Feyrer, Frederick; Fleishman, Erica

2010-07-01

We examined trends in abundance of four pelagic fish species (delta smelt, longfin smelt, striped bass, and threadfin shad) in the upper San Francisco Estuary, California, USA, over 40 years using Bayesian change point models. Change point models identify times of abrupt or unusual changes in absolute abundance (step changes) or in rates of change in abundance (trend changes). We coupled Bayesian model selection with linear regression splines to identify biotic or abiotic covariates with the strongest associations with abundances of each species. We then refitted change point models conditional on the selected covariates to explore whether those covariates could explain statistical trends or change points in species abundances. We also fitted a multispecies change point model that identified change points common to all species. All models included hierarchical structures to model data uncertainties, including observation errors and missing covariate values. There were step declines in abundances of all four species in the early 2000s, with a likely common decline in 2002. Abiotic variables, including water clarity, position of the 2 per thousand isohaline (X2), and the volume of freshwater exported from the estuary, explained some variation in species' abundances over the time series, but no selected covariates could explain statistically the post-2000 change points for any species.

Species abundance in a forest community in South China: A case of poisson lognormal distribution

USGS Publications Warehouse

Yin, Z.-Y.; Ren, H.; Zhang, Q.-M.; Peng, S.-L.; Guo, Q.-F.; Zhou, G.-Y.

2005-01-01

Case studies on Poisson lognormal distribution of species abundance have been rare, especially in forest communities. We propose a numerical method to fit the Poisson lognormal to the species abundance data at an evergreen mixed forest in the Dinghushan Biosphere Reserve, South China. Plants in the tree, shrub and herb layers in 25 quadrats of 20 m??20 m, 5 m??5 m, and 1 m??1 m were surveyed. Results indicated that: (i) for each layer, the observed species abundance with a similarly small median, mode, and a variance larger than the mean was reverse J-shaped and followed well the zero-truncated Poisson lognormal; (ii) the coefficient of variation, skewness and kurtosis of abundance, and two Poisson lognormal parameters (?? and ??) for shrub layer were closer to those for the herb layer than those for the tree layer; and (iii) from the tree to the shrub to the herb layer, the ?? and the coefficient of variation decreased, whereas diversity increased. We suggest that: (i) the species abundance distributions in the three layers reflects the overall community characteristics; (ii) the Poisson lognormal can describe the species abundance distribution in diverse communities with a few abundant species but many rare species; and (iii) 1/?? should be an alternative measure of diversity.

Abundance and community structure of ammonia-oxidizing Archaea and Bacteria in response to fertilization and mowing in a temperate steppe in Inner Mongolia.

PubMed

Chen, Yong-Liang; Hu, Hang-Wei; Han, Hong-Yan; Du, Yue; Wan, Shi-Qiang; Xu, Zhu-Wen; Chen, Bao-Dong

2014-07-01

Based on a 6-year field trial in a temperate steppe in Inner Mongolia, we investigated the effects of nitrogen (N) and phosphorus (P) fertilization and mowing on the abundance and community compositions of ammonia-oxidizing Bacteria (AOB) and Archaea (AOA) upon early (May) and peak (August) plant growth using quantitative PCR (qPCR), terminal-restriction fragment length polymorphism (T-RFLP), cloning and sequencing. The results showed that N fertilization changed AOB community composition and increased AOB abundance in both May and August, but significantly decreased AOA abundance in May. By contrast, P fertilization significantly influenced AOB abundance only in August. Mowing significantly decreased AOA abundance and had little effect on AOA community compositions in May, while significantly influencing AOB abundance in both May and August, Moreover, AOA and AOB community structures showed obvious seasonal variations between May and August. Phylogenetic analysis showed that all AOA sequences fell into the Nitrososphaera cluster, and the AOB community was dominated by Nitrosospira Cluster 3. The results suggest that fertilization and mowing play important roles in affecting the abundance and community compositions of AOA and AOB. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Douglas-fir forests in the Cascade Mountains of Oregon and Washington: is the abundance of small mammals related to stand age and moisture?

USGS Publications Warehouse

Coen, P.S.; Bury, R.B.; Spies, T.A.

1988-01-01

Red tree voles (Arborimus longicaudus) were the only small mammal strongly associated with old-growth forests, whereas vagrant shrews (Sorex vagrans) were most abundant in young forests. Pacific marsh shrews (S. bendirii) were most abundant in wet old-growth forests, but abundance of this species in young (wet) forests needs further study. Clearcuts had a mammalian fauna distinct from young forest stands. Abundance of several species was correlated to habitat features unique to naturally regenerated forests, indicated an urgent need to study the long-term effects of forest management to nongame wildlife.

Abundances of sodium, sulfur, and potassium in lunar volcanic glasses: Evidence for volatile loss during eruption

NASA Technical Reports Server (NTRS)

Delano, J. W.; Mcguire, J.

1992-01-01

Six varieties of lunar volcanic glass are known to occur within the Apollo 17 sample collection. Investigations have shown that 25 volatile elements are known to be concentrated on the exterior surfaces of individual volcanic glass spheres. Since bulk analyses of volcanic glass provide an integrated abundance of an element on and with the glass spherules, other methods must be relied on to determine the interior abundance of an element. The interior abundance of an element with a volcanic glass sphere establishes the abundance of that element in the melt at the time of quench. The current study is part of a comprehensive attempt to measure the abundance of three volatile elements (Na, S, and K) within representative spheres of the 25 varieties of lunar volcanic glass currently known to exist at the Apollo landing sites. Comparison of the measured abundances of these elements within the interiors of individual glasses with bulk analyses and crystalline mare basalts will furnish new constraints on the geochemical behavior of volatile elements during lunar mare volcanism.

Seasonality distribution of the abundance and activity of nitrification and denitrification microorganisms in sediments of surface flow constructed wetlands planted with Myriophyllum elatinoides during swine wastewater treatment.

PubMed

Li, Xi; Zhang, Miaomiao; Liu, Feng; Chen, Liang; Li, Yuyuan; Li, Yong; Xiao, Rulin; Wu, Jinshui

2018-01-01

Surface flow constructed wetlands (SFCWs) planted with Myriophyllum elatinoides for treatment of swine wastewater were examined to evaluate the effect of season, segment (site S1, S2, and S3), and treatment (100mgL -1 TN, T1; 300mgL -1 TN, T2; 500mgL -1 TN, T3) on the activity, and abundances of nitrifying and, denitrifying microorganisms, and on the abundance of sediment bacteria. The activity and abundances of nitrifiers, denitrifiers, and the abundance of bacteria were the highest in T3 samples, especially in S1 (P<0.05). The potential nitrification rate (PNR) was highest in the summer and potential denitrification rate (PDR) showed an increasing trend over seasons. The abundance of ammonia-oxidizing bacteria (AOB) was strongly correlated with PNR, while abundance of denitrifying gene (nirK) was strongly correlated with PDR. These results indicate that M. elatinoides SFCWs for swine wastewater treatment stimulate the growth of nitrifiers, denitrifiers and bacteria in sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way

NASA Astrophysics Data System (ADS)

Stanghellini, Letizia; Guerrero, Martín Antonio; Cunha, Katia; Manchado, Arturo; Villaver, Eva

2006-11-01

This paper presents a homogeneous study of abundances in a sample of 79 northern Galactic planetary nebulae (PNe) whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected optical line strengths in the literature, and elemental abundances were estimated with the ionization correction factor developed by Kingsbourgh & Barlow in 1994. We compare the elemental abundances to the final yields obtained from stellar evolution models of low- and intermediate-mass stars, and we confirm that most bipolar PNe have high nitrogen and helium abundance and are the likely progeny of stars with main-sequence mass greater than 3 Msolar. We derive =0.27 and discuss the implication of such a high ratio in connection with the solar neon abundance. We determine the Galactic gradients of oxygen and neon and found Δlog(O/H)/ΔR=-0.01 dex kpc-1 and Δlog(Ne/H)/ΔR=-0.01 dex kpc-1. These flat PN gradients are irreconcilable with Galactic metallicity gradients flattening with time.

When should we expect microbial phenotypic traits to predict microbial abundances?

PubMed

Fox, Jeremy W

2012-01-01

Species' phenotypic traits may predict their relative abundances. Intuitively, this is because locally abundant species have traits making them well-adapted to local abiotic and biotic conditions, while locally rare species are not as well-adapted. But this intuition may not be valid. If competing species vary in how well-adapted they are to local conditions, why doesn't the best-adapted species simply exclude the others entirely? But conversely, if species exhibit niche differences that allow them to coexist, then by definition there is no single best adapted species. Rather, demographic rates depend on species' relative abundances, so that phenotypic traits conferring high adaptedness do not necessarily confer high abundance. I illustrate these points using a simple theoretical model incorporating adjustable levels of "adaptedness" and "niche differences." Even very small niche differences can weaken or even reverse the expected correlation between adaptive traits and abundance. Conversely, adaptive traits confer high abundance when niche differences are very strong. Future work should be directed toward understanding the link between phenotypic traits and frequency-dependence of demographic rates.

Carbon and nitrogen abundances in red giant stars in the globular cluster 47 Tucanae

NASA Technical Reports Server (NTRS)

Dickens, R. J.; Bell, R. A.; Gustafsson, B.

1979-01-01

The effects of changes in temperature, gravity, overall metal abundance, and carbon and nitrogen abundances have been investigated for model stellar spectra and colors representing globular-cluster giants of moderate metal deficiency. The results are presented in the form of spectral atlases and theoretical color-color diagrams. Using these results, approximate abundances of carbon and nitrogen have been derived for some red giant stars in 47 Tuc, from intermediate- and low-dispersion spectra and from intermediate- and narrow-band photometry. In all the normal giants studied, nitrogen is overabundant by up to about a factor of 5 (the precise value depends on the adopted carbon abundance), with different enhancements for different giants. The observational material is not sufficient to distinguish between a normal carbon abundance and a slight carbon depletion for the giant-branch stars, but carbon appears to be somewhat depleted in stars on the asymptotic giant branch. A most probable value of M/H = -0.8 for the overall cluster metal abundance is suggested from analysis of Stromgren photometry of red horizontal-branch stars.

On the e-process - Its components and their neutron excesses. [solar abundance calculations in gamma ray astronomy

NASA Technical Reports Server (NTRS)

Hainebach, K. L.; Clayton, D. D.; Arnett, W. D.; Woosley, S. E.

1974-01-01

The pattern of abundances within the iron-abundance peak of the solar system is analyzed for various Cr, Fe, and Ni abundances, and a method is developed for finding the best fit to a given set of abundances with a chosen number of zones, i.e., mass contributions characterized by differing values of eta. This material can be synthesized by a superposition of e-process compositions in a low-eta region (eta = 0.003) and a high-eta region (eta = 0.065 -0.080) with at least 85% coming from the low-eta region. Addition of a third eta zone is unproductive. The applicability of the particle-poor freeze out is discussed in the light of these abundances, and the results of employing different numbers and types of zones are interpreted as an indication of the relative abundances themselves. Ejection of the low-eta zones is of great interest in gamma-ray astronomy and for empirical testing of theories of nucleosynthesis. The distribution of high zones should give important information about the formation of collapsed remnants.

Exploring the Nature of Galaxies with Abundance Gradient Anomalies in the SDSS-IV/MaNGA Survey

NASA Astrophysics Data System (ADS)

Keith, Celeste; Tremonti, Christy; Pace, Zach; Schaefer, Adam

2018-01-01

Disk galaxies are known to have radial oxygen abundance gradients with their centers being more chemically enriched than their outskirts. The steepness of the abundance gradient has recently been shown to correlate with galaxy stellar mass, on average. However, individual galaxies sometimes show pronounced deviations from the expected trends, such as flatter or steeper slopes than expected for their mass, abrupt changes in slope, or azimuthal asymmetries. Here we report on a systematic search for galaxies with abundance gradient anomalies using 2-D spectroscopy from the Sloan Digital Sky Survey IV MaNGA. We construct nebular oxygen and nitrogen abundance maps for 300 moderately inclined non-interacting disk galaxies and use visual inspection to identify the most interesting cases. We use this training set to develop an automated pipeline to flag galaxies with abundance anomalies from the larger MaNGA dataset for visual inspection. We combine the metallicity maps with kinematic data and measurements of the galaxies' local environments to better understand the processes that shape the radial abundance gradients of disk galaxies.

A Comparison of Observed Abundances in Five Well-Studied Planetary Nebulae

NASA Astrophysics Data System (ADS)

Tanner, Jolene; Balick, B.; Kwitter, K. B.

2013-01-01

We have assembled data and derived abundances in several recent careful studies for five bright planetary nebulae (PNe) of low, moderate, and high ionization and relatively simple morphology. Each of the studies employ different apertures, aperture placement, and facilities for the observations. Various methods were used to derive total abundances. All used spectral windows that included [OII]3727 in the UV through Argon lines in the red. Our ultimate goal is to determine the extent to which the derived abundances are consistent. We show that the reddening-corrected line ratios are surprisingly similar despite the different modes of observation and that the various abundance analysis methods yield generally consistent results for He/H, N/H, O/H, and Ne/H (within 50% with a few larger deviations). In addition we processed the line ratios from the different sources using a common abundance derivation method (ELSA) to search for clues of systematic methodological inconsistencies. None were uncovered.

Processes entangling interactions in communities: forbidden links are more important than abundance in a hummingbird-plant network.

PubMed

Vizentin-Bugoni, Jeferson; Maruyama, Pietro Kiyoshi; Sazima, Marlies

2014-04-07

Understanding the relative importance of multiple processes on structuring species interactions within communities is one of the major challenges in ecology. Here, we evaluated the relative importance of species abundance and forbidden links in structuring a hummingbird-plant interaction network from the Atlantic rainforest in Brazil. Our results show that models incorporating phenological overlapping and morphological matches were more accurate in predicting the observed interactions than models considering species abundance. This means that forbidden links, by imposing constraints on species interactions, play a greater role than species abundance in structuring the ecological network. We also show that using the frequency of interaction as a proxy for species abundance and network metrics to describe the detailed network structure might lead to biased conclusions regarding mechanisms generating network structure. Together, our findings suggest that species abundance can be a less important driver of species interactions in communities than previously thought.

Determination of Li abundance in Solar type stars of intermediate brightness

NASA Astrophysics Data System (ADS)

Amazo-Gómez, E. M.; Hernandez-Águila, B.; Dagostino, M. C.; Bertone, E.; de la Luz, V.

2014-10-01

The determination of the lithium abundance in stellar atmospheres is of fundamental importance in multiple contexts of contemporary astrophysics. On the one hand, the lithium present in stars with global sub-solar metal abundances provides a strong restriction on the abundance of this element as a result of primordial nucleo-synthesis. On the other hand, Li can be an age indicator for stars with convective envelopes. Additionally, Li abundance appears to be correlated with the presence of sub-stellar companions. We present preliminary results of a project aimed at determining the Li abundance in an extended sample of solar-like stars (spectral type G and luminosity class V) of intermediate brightness. High resolution spectroscopic data (R=65000) were obtained with the CanHiS echelle spectrograph on the 2.11m telescope of the Guillermo Haro Observatory in Cananea, Sonora, Mexico. We report the equivalent widths of a first sub-sample of 33 stars.

Species richness and relative species abundance of Nymphalidae (Lepidoptera) in three forests with different perturbations in the North-Central Caribbean of Costa Rica.

PubMed

Stephen, Carolyn; Sánchez, Ragde

2014-09-01

Measurements of species richness and species abundance can have important implications for regulations and conservation. This study investigated species richness and abundance of butterflies in the family Nymphalidae at undisturbed, and disturbed habitats in Tirimbina Biological Reserve and Nogal Private Reserve, Sarapiquí, Costa Rica. Traps baited with rotten banana were placed in the canopy and the understory of three habitats: within mature forest, at a river/forest border, and at a banana plantation/forest border. In total, 71 species and 487 individuals were caught and identified during May and June 2011 and May 2013. Species richness and species abundance were found to increase significantly at perturbed habitats (p < 0.0001, p < 0.0001, respectively). The edge effect, in which species richness and abundance increase due to greater complementary resources from different habitats, could be one possible explanation for increased species richness and abundance.

Processes entangling interactions in communities: forbidden links are more important than abundance in a hummingbird–plant network

PubMed Central

Vizentin-Bugoni, Jeferson; Maruyama, Pietro Kiyoshi; Sazima, Marlies

2014-01-01

Understanding the relative importance of multiple processes on structuring species interactions within communities is one of the major challenges in ecology. Here, we evaluated the relative importance of species abundance and forbidden links in structuring a hummingbird–plant interaction network from the Atlantic rainforest in Brazil. Our results show that models incorporating phenological overlapping and morphological matches were more accurate in predicting the observed interactions than models considering species abundance. This means that forbidden links, by imposing constraints on species interactions, play a greater role than species abundance in structuring the ecological network. We also show that using the frequency of interaction as a proxy for species abundance and network metrics to describe the detailed network structure might lead to biased conclusions regarding mechanisms generating network structure. Together, our findings suggest that species abundance can be a less important driver of species interactions in communities than previously thought. PMID:24552835

Carbon and nitrogen abundances determined from transition layer lines

NASA Technical Reports Server (NTRS)

Boehm-Vitense, Erika; Mena-Werth, Jose

1992-01-01

The possibility of determining relative carbon, nitrogen, and silicon abundances from the emission-line fluxes in the lower transition layers between stellar chromospheres and coronae is explored. Observations for main-sequence and luminosity class IV stars with presumably solar element abundances show that for the lower transition layers Em = BT sup -gamma. For a given carbon abundance the constants gamma and B in this relation can be determined from the C II and C IV emission-line fluxes. From the N V and S IV lines, the abundances of these elements relative to carbon can be determined from their surface emission-line fluxes. Ratios of N/C abundances determined in this way for some giants and supergiants agree within the limits of errors with those determined from molecular bands. For giants, an increase in the ratio of N/C at B-V of about 0.8 is found, as expected theoretically.

Abundances of the light elements from UV (HST) and red (ESO) spectra in the very old star HD 84937

NASA Astrophysics Data System (ADS)

Spite, M.; Peterson, R. C.; Gallagher, A. J.; Barbuy, B.; Spite, F.

2017-04-01

Aims: In order to provide a better basis for the study of mechanisms of nucleosynthesis of the light elements beyond hydrogen and helium in the oldest stars, the abundances of C, O, Mg, Si, P, S, K, and Ca have been derived from UV-HST and visible-ESO high resolution spectra in the old, very metal-poor star HD 84937, at a metallicity that is 1/200 that of the Sun's. For this halo main-sequence turnoff star, the abundance determination of P and S are the first published determinations. Methods: The LTE profiles of the lines were computed and fitted to the observed spectra. Wherever possible, we compared the abundances derived from the UV spectrum to abundances derived from the visible or near-infrared spectra, and also corrected the derived abundances for non-LTE effects. Three-dimensional (3D) CO5BOLD model atmospheres have been used to determine the abundances of C and O from molecular CH and OH bands. Results: The abundances of these light elements relative to iron in HD 84937 are found to agree well with the abundances of these elements in classical metal-poor stars. Our HD 84937 carbon abundance determination points toward a solar (or mildly enhanced above solar) value of [C/Fe]. The modest overabundance of the α elements of even atomic number Z, typical of halo turnoff stars, is confirmed in this example. The odd-Z element P is found to be somewhat deficient in HD 84937, at [P/Fe] = -0.32, which is again consistent with the handful of existing determinations for turnoff stars of such low metallicity. We show that the abundance of oxygen, deduced from the OH band from 3D computations, is not compatible with the abundance deduced from the red oxygen triplet. This incompatibility is explained by the existence of a chromosphere heating the shallow layers of the atmosphere where the OH band, in 3D computations, is mainly formed. Conclusions: The abundance ratios are compared to the predictions of models of galactic nucleosynthesis and evolution. Based on observations made with the NASA/ESA Hubble Space Telescope obtained under program GO-14161 at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA) and on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere (Archives of programmes 080.D-0347(A), 082.B-0610(A), 266.D-5655(A), and 073.D-0024(A) ).

Fear in grasslands: the effect of Eurasian kestrels on skylark abundances

NASA Astrophysics Data System (ADS)

Martínez-Padilla, Jesús; Fargallo, Juan A.

2008-05-01

Predation has received considerable theoretical and empirical support in population regulation. The effect of predators, however, could be achieved in direct (killing) or indirect effects (such as displacement). In this paper, we explored the relationship between Eurasian kestrels Falco tinnunculus and skylarks Alauda arvensis in Mediterranean grasslands. First, we analysed the presence of skylarks in the kestrel diet over 9 years. We also compared a grassland area of experimentally increased kestrel density and a second grassland as control area to evaluate the direct or indirect effect on skylark abundance. We also considered two different habitats, grazed and ungrazed plots. If skylark abundance decreased as the kestrel breeding season progressed in high-density kestrel area compared with the control area, it would suggest a direct effect (predator hypothesis). If skylark abundance remains constant in both areas of contrasting kestrel density, it would suggest that skylarks avoid kestrels (avoidance hypothesis). We found that skylark abundance decreased in the kestrel area from the beginning of kestrel nest-box installation to recent years. The rate of skylark consumption decreased in a 9-year period as kestrel abundance increased, although the total amount skylark consumption did not show a decreasing trend. In addition, skylarks were more abundant in the kestrel-free area than in the kestrel area. Finally, we found that skylark abundance did not change through the kestrel breeding period in relation to grazing. We suggest that an increased breeding density of kestrels during their breeding period may force the skylarks to breed in other areas, which may explain the decline of their abundance.

Far and Wide - Microbial Bebop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Larsen

2012-10-01

This musical composition was created from data of microbes (bacteria, algae and other microorganisms) sampled in the English Channel. Argonne National Laboratory biologist Peter Larsen created the songs as a unique way to present and comprehend large datasets. Microbial species of the Order Rickettsiales, such as the highly abundant, free-living planktonic species Pelagibacter ubique, are typical highly abundant taxa in L4 Station data. Its relative abundance in the microbial community at L4 Station follows a distinctive seasonal pattern. In this composition, there are two chords per measure, generated from photosynthetically active radiation measurements and temperature. The melody of each measuremore » is six notes that describe the relative abundance of the Order Rickettsiales. The first note of each measure is from the relative abundance at a time point. The next five notes of a measure follow one of the following patterns: a continuous rise in pitch, a continuous drop in pitch, a rise then drop in pitch, or a drop then rise in pitch. These patterns are matched to the relative abundance of Rickettsiales at the given time point, relative to the previous and subsequent time points. The pattern of notes in a measure is mapped to the relative abundance of Rickettsiales with fewer rests per measure indicating higher abundance. For time points at which Rickettsiales was the most abundant microbial taxa, the corresponding measure is highlighted with a cymbal crash. More information at http://www.anl.gov/articles/songs-key... Image: Diatoms under a microscope: These tiny phytoplankton are encased within a silicate cell wall. Credit: Prof. Gordon T. Taylor, Stony Brook University« less

Harvest-related edge effects on prey availability and foraging of hooded warblers in a bottomland hardwood forest.

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Kilgo

2005-04-20

The effects of harvest-created canopy gaps in bottomland hardwood forests on arthropod abundance and, hence, the foraging ecology of birds are poorly understood. I predicted that arthropod abundance would be high near edges of group-selection harvest gaps and lower in the surrounding forest, and that male Hooded Warblers (Wilsonia citrina) foraging near gaps would find more prey per unit time than those foraging in the surrounding forest. In fact, arthropod abundance was greater >100 m from a gap edge than at 0-30 m or 30-100 m from an edge, due to their abundance on switchcane (Arundinaria gigantea); arthropods did notmore » differ in abundance among distances from gaps on oaks (Quercus spp.) or red maple (Acer rubrum). Similarly, Hooded Warbler foraging attack rates were not higher near gap edges: when foraging for fledglings, attack rate did not differ among distances from gaps, but when foraging for themselves, attack rates actually were lower 0-30 m from gap edges than 30-100 m or >100 m from a gap edge. Foraging attack rate was positively associated with arthropod abundance. Hooded Warblers apparently encountered fewer prey and presumably foraged less efficiently where arthropods were least abundant, i.e., near gaps. That attack rates among birds foraging for fledglings were not affected by distance from gap (and hence arthropod abundance) suggests that prey availability may not be limiting at any location across the forest, despite the depressing effects of gaps on arthropod abundance.« less

Host trait combinations drive abundance and canopy distribution of atmospheric bromeliad assemblages.

PubMed

Chaves, Cleber Juliano Neves; Dyonisio, Júlio César; Rossatto, Davi Rodrigo

2016-01-01

Epiphytes are strongly dependent on the conditions created by their host's traits and a certain degree of specificity is expected between them, even if these species are largely abundant in a series of tree hosts of a given environment, as in the case of atmospheric bromeliads. Despite their considerable abundance in these environments, we hypothesize that stochasticity alone cannot explain the presence and abundance of atmospheric bromeliads on host trees, since host traits could have a greater influence on the establishment of these bromeliads. We used secondary and reforested seasonal forests and three distinct silvicultures to test whether species richness, phylogenetic diversity and functional diversity of trees can predict the differential presence, abundance and distribution of atmospheric bromeliads on hosts. We compared the observed parameters of their assemblage with null models and performed successive variance hierarchic partitions of abundance and distribution of the assemblage to detect the influence of multiple traits of the tree hosts. Our results do not indicate direct relationships between the abundance of atmospheric bromeliads and phylogenetic or functional diversity of trees, but instead indicate that bromeliads occurred on fewer tree species than expected by chance. We distinguished functional tree patterns that can improve or reduce the abundance of atmospheric bromeliads, and change their distribution on branches and trunk. While individual tree traits are related to increased abundance, species traits are related to the canopy distribution of atmospheric bromeliad assemblages. A balance among these tree functional patterns drives the atmospheric bromeliad assemblage of the forest patches. Published by Oxford University Press on behalf of the Annals of Botany Company.

AKARI observations of brown dwarfs. IV. Effect of elemental abundances on near-infrared spectra between 1.0 and 5.0 μm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorahana, S.; Yamamura, I.

2014-09-20

The detection of the CO{sub 2} absorption band at 4.2 μm in brown dwarf spectra by AKARI has made it possible to discuss CO{sub 2} molecular abundance in brown dwarf atmospheres. In our previous studies, we found an excess in the 4.2 μm CO{sub 2} absorption band of three brown dwarf spectra, and suggested that these deviations were caused by high C and O elemental abundances in their atmospheres. To validate this hypothesis, we have constructed a set of models of brown dwarf atmospheres with various elemental abundance patterns, and we investigate the variations of the molecular composition and themore » thermal structure, and how they affect the near-infrared spectra between 1.0 and 5.0 μm. The 4.2 μm CO{sub 2} absorption band in some late-L and T dwarfs taken by AKARI is stronger or weaker than predicted by corresponding models with solar abundance. By comparing the CO{sub 2} band in the model spectra to the observed near-infrared spectra, we confirm possible elemental abundance variations among brown dwarfs. We find that the band strength is especially sensitive to O abundance, but C is also needed to reproduce the entire near-infrared spectra. This result indicates that both the C and O abundances should increase and decrease simultaneously for brown dwarfs. We find that a weaker CO{sub 2} absorption band in a spectrum can also be explained by a model with lower 'C and O' abundances.« less

Improved Yttrium and Zirconium Abundances in Metal-Poor Stars

NASA Astrophysics Data System (ADS)

Violante, Renata; Biemont, E.; Cowan, J. J.; Sneden, C.

2012-01-01

Abstract We present new abundances of the lighter n-capture elements, Yttrium (Z=39) and Zirconium (Z=40) in the very metal poor, r-process rich stars BD+17 3248 and HD 221170. Very accurate abundances were obtained by use of the new transition probabilities for Y II published by Biémont et al. 2011, and Zr II by Malcheva et al. 2006, and by expanding the number of transitions employed for each element. For example, in BD+17 3248, we find log ɛπσιλον=-0.03 +/- 0.03 (σιγμα=0.15, from 23 lines) for Y II. As for Zr II, log ɛπσιλον = 0.65 +/- 0.03 (σɛγμα = 0.1, from 13 lines). The resulting abundance ratio is log ɛπσιλον [Y/Zr] = -0.68 +/- 0.05. The results for HD 221170 are in accord with those of BD+17 3248. The quantity of lines used to form the abundance means has increased significantly since the original studies of these stars, resulting in more trustworthy abundances. These observed abundance ratios are in agreement with an r-process-only value predicted from stellar models, but is under-abundant compared to an empirical model derived from direct analyses of meteoritic material. This ambiguity should stimulate further nucleosynthetic analysis to explain this abundance ratio. We would like to extend our gratitude to NSF grant AST-0908978 and the University of Texas Astronomy Department Rex G. Baker, Jr. Endowment for their financial support in this project.

Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.;

Evidence for competition at sea between Norton Sound chum salmon and Asian hatchery chum salmon

USGS Publications Warehouse

Ruggerone, Gregory T.; Agler, B.A.; Nielsen, Jennifer L.

2012-01-01

Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap in the ocean, and wild salmon populations having low productivity may compete for food with abundant hatchery populations. We tested the hypothesis that adult length-at-age, age-at-maturation, productivity, and abundance of a Norton Sound, Alaska, chum salmon population were influenced by Asian hatchery chum salmon, which have become exceptionally abundant and surpassed the abundance of wild chum salmon in the North Pacific beginning in the early 1980s. We found that smaller adult length-at-age, delayed age-at-maturation, and reduced productivity and abundance of the Norton Sound salmon population were associated with greater production of Asian hatchery chum salmon since 1965. Modeling of the density-dependent relationship, while controlling for other influential variables, indicated that an increase in adult hatchery chum salmon abundance from 10 million to 80 million adult fish led to a 72% reduction in the abundance of the wild chum salmon population. These findings indicate that competition with hatchery chum salmon contributed to the low productivity and abundance of Norton Sound chum salmon, which includes several stocks that are classified as Stocks of Concern by the State of Alaska. This study provides new evidence indicating that large-scale hatchery production may influence body size, age-at-maturation, productivity and abundance of a distant wild salmon population.

Combining occurrence and abundance distribution models for the conservation of the Great Bustard.

PubMed

Mi, Chunrong; Huettmann, Falk; Sun, Rui; Guo, Yumin

2017-01-01

Species distribution models (SDMs) have become important and essential tools in conservation and management. However, SDMs built with count data, referred to as species abundance models (SAMs), are still less commonly used to date, but increasingly receiving attention. Species occurrence and abundance do not frequently display similar patterns, and often they are not even well correlated. Therefore, only using information based on SDMs or SAMs leads to an insufficient or misleading conservation efforts. How to combine information from SDMs and SAMs and how to apply the combined information to achieve unified conservation remains a challenge. In this study, we introduce and propose a priority protection index (PI). The PI combines the prediction results of the occurrence and abundance models. As a case study, we used the best-available presence and count records for an endangered farmland species, the Great Bustard ( Otis tarda dybowskii ), in Bohai Bay, China. We then applied the Random Forest algorithm (Salford Systems Ltd. Implementation) with eleven predictor variables to forecast the spatial occurrence as well as the abundance distribution. The results show that the occurrence model had a decent performance (ROC: 0.77) and the abundance model had a RMSE of 26.54. It is noteworthy that environmental variables influenced bustard occurrence and abundance differently. The area of farmland, and the distance to residential areas were the top important variables influencing bustard occurrence. While the distance to national roads and to expressways were the most important influencing abundance. In addition, the occurrence and abundance models displayed different spatial distribution patterns. The regions with a high index of occurrence were concentrated in the south-central part of the study area; and the abundance distribution showed high populations occurrence in the central and northwestern parts of the study area. However, combining occurrence and abundance indices to produce a priority protection index (PI) to be used for conservation could guide the protection of the areas with high occurrence and high abundance (e.g., in Strategic Conservation Planning). Due to the widespread use of SDMs and the easy subsequent employment of SAMs, these findings have a wide relevance and applicability than just those only based on SDMs or SAMs. We promote and strongly encourage researchers to further test, apply and update the priority protection index (PI) elsewhere to explore the generality of these findings and methods that are now readily available.

Combining occurrence and abundance distribution models for the conservation of the Great Bustard

PubMed Central

Mi, Chunrong; Huettmann, Falk; Sun, Rui

2017-01-01

Species distribution models (SDMs) have become important and essential tools in conservation and management. However, SDMs built with count data, referred to as species abundance models (SAMs), are still less commonly used to date, but increasingly receiving attention. Species occurrence and abundance do not frequently display similar patterns, and often they are not even well correlated. Therefore, only using information based on SDMs or SAMs leads to an insufficient or misleading conservation efforts. How to combine information from SDMs and SAMs and how to apply the combined information to achieve unified conservation remains a challenge. In this study, we introduce and propose a priority protection index (PI). The PI combines the prediction results of the occurrence and abundance models. As a case study, we used the best-available presence and count records for an endangered farmland species, the Great Bustard (Otis tarda dybowskii), in Bohai Bay, China. We then applied the Random Forest algorithm (Salford Systems Ltd. Implementation) with eleven predictor variables to forecast the spatial occurrence as well as the abundance distribution. The results show that the occurrence model had a decent performance (ROC: 0.77) and the abundance model had a RMSE of 26.54. It is noteworthy that environmental variables influenced bustard occurrence and abundance differently. The area of farmland, and the distance to residential areas were the top important variables influencing bustard occurrence. While the distance to national roads and to expressways were the most important influencing abundance. In addition, the occurrence and abundance models displayed different spatial distribution patterns. The regions with a high index of occurrence were concentrated in the south-central part of the study area; and the abundance distribution showed high populations occurrence in the central and northwestern parts of the study area. However, combining occurrence and abundance indices to produce a priority protection index (PI) to be used for conservation could guide the protection of the areas with high occurrence and high abundance (e.g., in Strategic Conservation Planning). Due to the widespread use of SDMs and the easy subsequent employment of SAMs, these findings have a wide relevance and applicability than just those only based on SDMs or SAMs. We promote and strongly encourage researchers to further test, apply and update the priority protection index (PI) elsewhere to explore the generality of these findings and methods that are now readily available. PMID:29255652

Wood thrush nest success and post-fledging survival across a temporal pulse of small mammal abundance in an oak forest.

PubMed

Schmidt, Kenneth A; Rush, Scott A; Ostfeld, Richard S

2008-07-01

1. Synchronized mass production of seed crops, such as acorns, produces a resource pulse that may have far-reaching consequences for songbird populations through its effects on avian predators. Seed production in these forests represents only the first of several pulsed events. Secondary pulses emerge as mast-consuming rodents numerically respond to seed production and tertiary pulses emerge as generalist predators, such as raptors, numerically respond to rodents. In turn, these two groups reduce nest productivity and juvenile survivorship 1 and 2 years, respectively, after the initial pulse in seed production. 2. At our study site in south-eastern New York, USA, autumn acorn abundance (primary pulse) largely determines rodent abundance (secondary pulse) the following spring. We tested the hypotheses that the population dynamics of a shrub-nesting passerine (wood thrush Hylocichla mustelina), is influenced by rodents through the: (a) direct effect of predation by rodents; (b) indirect effect of rodents on the abundance of raptors (tertiary pulse); and (c) indirect effect of rodent abundance on raptor diet. The latter specifically hypothesizes that a crash in the rodent population in the wake of region-wide failure of acorn production leads to an extreme diet shift in raptors that increases post-fledging mortality in birds. 3. We conducted a 3-year study to examine variation in wood thrush nest success and fledgling survival, using radio telemetry, across a pulse of rodent abundance (i.e. low, medium and high). We also updated and reanalysed regional wood thrush population growth rates as a function of the annual variation in rodent abundance. 4. Fledgling survivorship, but not nest success, varied in relation to annual rodent abundance. Raptors and eastern chipmunks Tamias striatus were the most commonly identified predators on fledglings. Fledgling survivorship was greatest at intermediate rodent abundance consistent with a shift in raptor diet. Regional rate of wood thrush population growth showed a unimodal relationship with rodent abundance, peaking during years with intermediate rodent abundance. This unimodal pattern was due to wood thrush population growth rates near or below zero during rodent population crashes. 5. The telemetry study, pattern of regional abundance and synchronized population dynamics of coexisting thrushes suggest a common mechanism of behavioural changes in raptors in response to declines in rodent prey, which in turn affects thrush population dynamics.

Elemental abundances via X-ray observations of galaxy clusters and the InFOCmuS hard X-ray telescope

NASA Astrophysics Data System (ADS)

Baumgartner, Wayne H.

2004-08-01

The first part of this dissertation deals with the oxygen abundance of the Milky Way interstellar medium. Previous measurements had shown that oxygen in the ISM was depleted compared to its abundance in the sun. This dissertation presents new measurements of the ISM oxygen abundance taken in the X-ray band by observing the oxygen 0.6 keV photoionization K-edge in absorption towards 10 galaxy clusters. These measurements show that the ISM oxygen abundance is 0.9 solar, much greater than earlier depleted values. The oxygen abundance is found to be uniform across our 10 lines of sight, showing that it is not dependent on the depth of the hydrogen column. This implies that the galactic oxygen abundance does not depend on density, and that it is the same in dense clouds and in the more diffuse ISM. The next part of the dissertation measures elemental abundances in the galaxy clusters themselves. The abundances of the elements iron, silicon, sulfur, calcium, argon, and nickel are measured using the strong resonance K-shell emission lines in the X-ray band. Over 300 clusters from the ASCA archives are analyzed with a joint fitting procedure to improve the S/N ratio and provide the first average abundance results for clusters as a function of mass. The α elements silicon, sulfur, argon and calcium are not found to have similar abundances as expected from their supposed common origin. Also, no combination of SN Ia and SN II yields can account for the cluster abundance ratios, perhaps necessitating a contribution from a cosmologically early generation of massive population III stars. The last part of this dissertation details the development of the Cadmium Zinc Telluride (CZT) detectors on the InFOCμS hard X-ray telescope. InFOCμS is a balloon-borne imaging spectrometer that incorporates multi-layer coated grazing-incidence optics and CZT detectors. These detectors are well suited for hard X-ray astronomy because their large bandgap and high atomic number allow for efficient room temperature detection of photons in the 20 150 keV band. The InFOCμS CZT detectors achieve an energy resolution of 4.8 keV. A 2000 flight to measure the inflight background is discussed, as well as the results of a 2001 flight to observe Cyg X- 1.

Globular Cluster Abundances from High-resolution, Integrated-light Spectroscopy. IV. The Large Magellanic Cloud: α, Fe-peak, Light, and Heavy Elements

NASA Astrophysics Data System (ADS)

Colucci, Janet E.; Bernstein, Rebecca A.; Cameron, Scott A.; McWilliam, Andrew

2012-02-01

We present detailed chemical abundances in eight clusters in the Large Magellanic Cloud (LMC). We measure abundances of 22 elements for clusters spanning a range in age of 0.05-12 Gyr, providing a comprehensive picture of the chemical enrichment and star formation history of the LMC. The abundances were obtained from individual absorption lines using a new method for analysis of high-resolution (R ~ 25,000), integrated-light (IL) spectra of star clusters. This method was developed and presented in Papers I, II, and III of this series. In this paper, we develop an additional IL χ2-minimization spectral synthesis technique to facilitate measurement of weak (~15 mÅ) spectral lines and abundances in low signal-to-noise ratio data (S/N ~ 30). Additionally, we supplement the IL abundance measurements with detailed abundances that we measure for individual stars in the youngest clusters (age < 2 Gyr) in our sample. In both the IL and stellar abundances we find evolution of [α/Fe] with [Fe/H] and age. Fe-peak abundance ratios are similar to those in the Milky Way (MW), with the exception of [Cu/Fe] and [Mn/Fe], which are sub-solar at high metallicities. The heavy elements Ba, La, Nd, Sm, and Eu are significantly enhanced in the youngest clusters. Also, the heavy to light s-process ratio is elevated relative to the MW ([Ba/Y] >+0.5) and increases with decreasing age, indicating a strong contribution of low-metallicity asymptotic giant branch star ejecta to the interstellar medium throughout the later history of the LMC. We also find a correlation of IL Na and Al abundances with cluster mass in the sense that more massive, older clusters are enriched in the light elements Na and Al with respect to Fe, which implies that these clusters harbor star-to-star abundance variations as is common in the MW. Lower mass, intermediate-age, and young clusters have Na and Al abundances that are lower and more consistent with LMC field stars. Our results can be used to constrain both future chemical evolution models for the LMC and theories of globular cluster formation. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

NASA Technical Reports Server (NTRS)

Rau, G. H.; Desmarais, David J.

1985-01-01

Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

Bulk and rare earth abundances in the Luna 16 soil levels A and D.

NASA Technical Reports Server (NTRS)

Gillum, D. E.; Ehmann, W. D.; Wakita, H.; Schmitt, R. A.

1972-01-01

Determination of the abundances of major, minor, and trace elements by means of sequential INAA (instrumental neutron activation analysis) in two Luna 16 soils, at levels A (about 7 cm depth) and D (about 30 cm depth). Abundances of the bulk elements in Luna 16 soils generally agree with the values reported by Vinogradov (1971). Elemental abundances of both bulk and trace elements are nearly the same for the two A and D soil levels. Overall, the chemical compositions of the two Luna 16 soils are more closely related to Apollo 11 soil 10084 than to Apollo 12 and 14 soils, with the exception of TiO2 abundances.-

The relative abundance of neon and magnesium in the solar corona

NASA Technical Reports Server (NTRS)

Rugge, H. R.; Walker, A. B. C., Jr.

1976-01-01

A technique is proposed for specifically determining the relative solar coronal abundance of neon and magnesium. The relative abundance is calculated directly from the relative intensity of the resonance lines of Ne X (12.134A) and Mg XI (9.169A) without the need for the development of a detailed model of the thermal structure of the corona. Moderate resolution Bragg crystal spectrometer results from the OVI-10 satellite were used to determine a coronal neon to magnesium relative abundance of 1.47 + or - 0.38. The application of this technique to a recent higher resolution rocket observation gave an abundance ratio of approximately 0.93 + or - 0.15.

Column abundance measurements of atmospheric hydroxyl at 45 deg S

NASA Technical Reports Server (NTRS)

Wood, S. W.; Keep, D. J.; Burnett, C. R.; Burnett, E. B.

1994-01-01

The first Southern Hemisphere measurements of the vertical column abundance of atmospheric hydroxyl (OH) have been obtained at Lauder, New Zealand (45 deg S) with a PEPSIOS instrument measuring the absorption of sunlight at 308 nm. The variation of column OH with solar zenith angle is similar to that measured at other sites. However average annual abundances of OH are about 20% higher than those found by similar measurements at 40 deg N. Minimum OH abundances about 10% less than average levels at 40 deg N, are observed during austral spring. The OH abundance abruptly increases by 30% in early summer and remains at the elevated level until late the following winter.

Fluorine Abundances in AGB Carbon Stars: New Results?

NASA Astrophysics Data System (ADS)

Abia, C.; de Laverny, P.; Recio-Blanco, A.; Domínguez, I.; Cristallo, S.; Straniero, O.

2009-09-01

A recent reanalysis of the fluorine abundance in three Galactic Asymptotic Giant Branch (AGB) carbon stars (TX Psc, AQ Sgr and R Scl) by Abia et al. (2009) results in estimates of fluorine abundances systematically lower by ~0.8 dex on average, with respect to the sole previous estimates by Jorissen, Smith & Lambert (1992). The new F abundances are in better agreement with the predictions of full-network stellar models of low-mass (<3 Msolar) AGB stars.

A Preliminary Assessment of Mouflon Abundance at the Kahuku Unit of Hawaii Volcanoes National Park

DTIC Science & Technology

2006-01-01

of Mouflon Abundance at the Kahuku Unit of Hawaii Volcanoes National Park Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting...Preliminary Assessment of Mouflon Abundance at the Kahuku Unit of Hawaii Volcanoes National Park 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...of Hawaii Volcanoes National Park in November 2004. Photograph by Ben Kawakami Jr. A Preliminary Assessment of Mouflon Abundance at the Kahuku Unit

Systematic Variations in CO2/H2O Ice Abundance Ratios in Nearby Galaxies Found with AKARI Near-infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Onaka, T.; Shimonishi, T.; Suzuki, T.

2015-07-01

We report CO2/H2O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5-5.0 μm) spectra. The CO2/H2O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO2/H2O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO2/H2O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO2/H2O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO2/H2O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO2/H2O ice abundance ratios tend to be high in young star-forming galaxies.

The activated sludge ecosystem contains a core community of abundant organisms

PubMed Central

Saunders, Aaron M; Albertsen, Mads; Vollertsen, Jes; Nielsen, Per H

2016-01-01

Understanding the microbial ecology of a system requires that the observed population dynamics can be linked to their metabolic functions. However, functional characterization is laborious and the choice of organisms should be prioritized to those that are frequently abundant (core) or transiently abundant, which are therefore putatively make the greatest contribution to carbon turnover in the system. We analyzed the microbial communities in 13 Danish wastewater treatment plants with nutrient removal in consecutive years and a single plant periodically over 6 years, using Illumina sequencing of 16S ribosomal RNA amplicons of the V4 region. The plants contained a core community of 63 abundant genus-level operational taxonomic units (OTUs) that made up 68% of the total reads. A core community consisting of abundant OTUs was also observed within the incoming wastewater to three plants. The net growth rate for individual OTUs was quantified using mass balance, and it was found that 10% of the total reads in the activated sludge were from slow or non-growing OTUs, and that their measured abundance was primarily because of immigration with the wastewater. Transiently abundant organisms were also identified. Among them the genus Nitrotoga (class Betaproteobacteria) was the most abundant putative nitrite oxidizer in a number of activated sludge plants, which challenges previous assumptions that Nitrospira (phylum Nitrospirae) are the primary nitrite-oxidizers in activated sludge systems with nutrient removal. PMID:26262816

Effects of seasonality on drosophilids (Insecta, Diptera) in the northern part of the Atlantic Forest, Brazil.

PubMed

Coutinho-Silva, R D; Montes, M A; Oliveira, G F; de Carvalho-Neto, F G; Rohde, C; Garcia, A C L

2017-10-01

Seasonality is an important aspect associated with population dynamic and structure of tropical insect assemblages. This study evaluated the effects of seasonality on abundance, richness, diversity and composition of an insect group, drosophilids, including species native to the Neotropical region and exotic ones. Three preserved fragments of the northern Atlantic Forest were surveyed, where temperatures are above 20 °C throughout the year and rainfall regimes define two seasons (dry and rainy). As opposed to other studies about arthropods in tropical regions, we observed that abundance of drosophilids was significantly higher in the dry season, possibly due to biological aspects and the colonization strategy adopted by the exotic species in these environments. Contrarily to abundance, we did not observe a seasonal pattern for richness. As for other parts of the Atlantic Forest, the most representative Neotropical species (Drosophila willistoni, D. sturtevanti, D. paulistorum and D. prosaltans) were significantly more abundant in the rainy season. Among the most abundant exotic species, D. malerkotliana, Zaprionus indianus and Scaptodrosophila latifasciaeformis were more importantly represented the dry season, while D. simulans was more abundant in the rainy period. The seasonality patterns exhibited by the most abundant species were compared to findings published in other studies. Our results indicate that exotic species were significantly more abundant in the dry season, while native ones exhibited an opposite pattern.

Targeted proteome analysis of single-gene deletion strains of Saccharomyces cerevisiae lacking enzymes in the central carbon metabolism.

PubMed

Matsuda, Fumio; Kinoshita, Syohei; Nishino, Shunsuke; Tomita, Atsumi; Shimizu, Hiroshi

2017-01-01

Central carbon metabolism is controlled by modulating the protein abundance profiles of enzymes that maintain the essential systems in living organisms. In this study, metabolic adaptation mechanisms in the model organism Saccharomyces cerevisiae were investigated by direct determination of enzyme abundance levels in 30 wild type and mutant strains. We performed a targeted proteome analysis using S. cerevisiae strains that lack genes encoding the enzymes responsible for central carbon metabolism. Our analysis revealed that at least 30% of the observed variations in enzyme abundance levels could be explained by global regulatory mechanisms. A enzyme-enzyme co-abundance analysis revealed that the abundances of enzyme proteins involved in the trehalose metabolism and glycolysis changed in a coordinated manner under the control of the transcription factors for global regulation. The remaining variations were derived from local mechanisms such as a mutant-specific increase in the abundances of remote enzymes. The proteome data also suggested that, although the functional compensation of the deficient enzyme was attained by using more resources for protein biosynthesis, available resources for the biosynthesis of the enzymes responsible for central metabolism were not abundant in S. cerevisiae cells. These results showed that global and local regulation of enzyme abundance levels shape central carbon metabolism in S. cerevisiae by using a limited resource for protein biosynthesis.

Messages from the Reversing Layer: Clues to Planet Formation in Spectral Abundances

NASA Astrophysics Data System (ADS)

Brewer, John Michael; Fischer, Debra; Basu, Sarbani

2017-01-01

The abundances of elements in the protoplanetary disk evolve over time, but stellar abundances will reflect the initial chemical composition of the disk and this can provide constraints on the range of possible outcomes for planet interiors. Rocky planet habitability depends not just on the availability of liquid water, but also on volcansim and plate tectonics that can stabilize the climate on long timescales. The slow evolution of abundances in stellar photospheres, particularly abundance ratios between elements, makes them ideal laboratories to study primordial disk compositions.In my thesis work, I developed a new spectroscopic analysis procedure that derives gravities consistent with asteroseismology to within 0.05 dex as well as abundances for 15 elements. Using this procedure, we analyzed and published a catalog of accurate stellar parameters and precise abundances for more than 1600 stars and used those to investigate questions of planet formation. The C/O and Mg/Si ratios in the solar neighborhood could affect rocky planet habitability. For lucky cases where planet atmosphereic abundances can be measured, the stellar host C/O and [O/H] ratios carry information about the formation site and migration of hot Jupiters. I will present results on both rocky planet compositions and hot Jupiter migration and discuss how they can help us identify potentially habitable systems and discriminate between different planet formation models.

Effects of conifer release with glyphosate on summer forage abundance for deer in Maine

USGS Publications Warehouse

Vreeland, J.K.; Servello, F.A.; Griffith, B.

1998-01-01

Effects of conifer release with glyphosate on summer forage availability for large herbivores in northern forests have received relatively little study. We determined effects of glyphosate treatment of clearcuts on abundance of summer foods for white-tailed deer (Odocoileus virginianus) at 1 and 7-10 years posttreatment. We measured the abundance (percent cover in a 0- to 1.8-m height stratum) of five forage classes for deer (leaves of deciduous trees, leaves of deciduous shrubs, forbs, grasses, ferns) on 12 clearcuts (six treated, six untreated) to determine 1-year effects and on 10 clearcuts (five treated, five untreated) to determine 7- to 10-year effects. Abundance of leaves of deciduous trees was greater on untreated sites (38 versus 11%) at 1 year posttreatment, but the difference was less (18 versus 12%) at 7-10 years posttreatment (age x treatment interaction, P = 0.005). Leaves of deciduous shrubs exhibited a similar pattern. Abundance of forbs was similar (13-14%) at 1 year posttreatment but greater on treated sites (29 versus 15%) at 7-10 years posttreatment (P = 0.03). Grasses and ferns were less abundant than other forage classes. Overall, glyphosate application initially decreased the abundance of leaves of deciduous trees and shrubs used as food in summer, but the longer term positive effects on forb abundance may result in little net change in overall habitat value.

Juvenile Chinook Salmon abundance in the northern Bering Sea: Implications for future returns and fisheries in the Yukon River

NASA Astrophysics Data System (ADS)

Murphy, James M.; Howard, Kathrine G.; Gann, Jeanette C.; Cieciel, Kristin C.; Templin, William D.; Guthrie, Charles M.

2017-01-01

Juvenile Chinook Salmon (Oncorhynchus tshawytscha) abundance in the northern Bering Sea is used to provide insight into future returns and fisheries in the Yukon River. The status of Yukon River Chinook Salmon is of concern due to recent production declines and subsequent closures of commercial, sport, and personal use fisheries, and severe restrictions on subsistence fisheries in the Yukon River. Surface trawl catch data, mixed layer depth adjustments, and genetic stock mixtures are used to estimate juvenile abundance for the Canadian-origin stock group from the Yukon River. Abundance ranged from a low of 0.62 million in 2012 to a high of 2.58 million in 2013 with an overall average of 1.5 million from 2003 to 2015. Although abundance estimates indicate that average survival is relatively low (average of 5.2%), juvenile abundance was significantly correlated (r=0.87, p=0.005) with adult returns, indicating that much of the variability in survival occurs during early life-history stages (freshwater and initial marine). Juvenile abundance in the northern Bering Sea has increased since 2013 due to an increase in early life-history survival (average juveniles-per-spawner increased from 29 to 59). The increase in juvenile abundance is projected to produce larger runs and increased subsistence fishing opportunities for Chinook Salmon in the Yukon River as early as 2016.

Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

PubMed Central

Dutcher, James D.; Karar, Haider; Abbas, Ghulam

2012-01-01

Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011) from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids. PMID:26466738

Dam removal increases American eel abundance in distant headwater streams

USGS Publications Warehouse

Hitt, Nathaniel P.; Eyler, Sheila; Wofford, John E.B.

2012-01-01

American eel Anguilla rostrata abundances have undergone significant declines over the last 50 years, and migration barriers have been recognized as a contributing cause. We evaluated eel abundances in headwater streams of Shenandoah National Park, Virginia, to compare sites before and after the removal of a large downstream dam in 2004 (Embrey Dam, Rappahannock River). Eel abundances in headwater streams increased significantly after the removal of Embrey Dam. Observed eel abundances after dam removal exceeded predictions derived from autoregressive models parameterized with data prior to dam removal. Mann–Kendall analyses also revealed consistent increases in eel abundances from 2004 to 2010 but inconsistent temporal trends before dam removal. Increasing eel numbers could not be attributed to changes in local physical habitat (i.e., mean stream depth or substrate size) or regional population dynamics (i.e., abundances in Maryland streams or Virginia estuaries). Dam removal was associated with decreasing minimum eel lengths in headwater streams, suggesting that the dam previously impeded migration of many small-bodied individuals (<300 mm TL). We hypothesize that restoring connectivity to headwater streams could increase eel population growth rates by increasing female eel numbers and fecundity. This study demonstrated that dams may influence eel abundances in headwater streams up to 150 river kilometers distant, and that dam removal may provide benefits for eel management and conservation at the landscape scale.

High Resolution Optical Spectroscopy of an Intriguing High-Latitude B-Type Star HD119608

NASA Astrophysics Data System (ADS)

Şahin, T.

2018-01-01

We present an LTE analysis of high resolution echelle optical spectra obtained with the 3.9-m Anglo-Australian Telescope (AAT) and the UCLES spectrograph for a B1Ib high galactic latitude supergiant HD119608. A fresh determination of the atmospheric parameters using line-blanketed LTE model atmospheres and spectral synthesis provided T eff = 23 300 ± 1000 K, log g = 3.0 ± 0.3, and the microturbulent velocity ξ = 6.0 ± 1.0 kms-1 and [Fe/H] = 0.16. The rotational velocity of the star was derived fromC, O, N, Al, and Fe lines as v sin i = 55.8 ± 1.3 kms-1. Elemental abundances were obtained for 10 different species. He, Al, and P abundances of the star were determined for the first time. In the spectra, hot post-AGB status as well as the Pop I characteristics of the star were examined. The approximately solar carbon and oxygen abundances, along with mild excess in helium and nitrogen abundances do not stipulate a CNO processed surface composition, hence a hot post-AGB status. The LTE abundances analysis also indicates solar sulphur and moderately enriched magnesium abundances. The average abundances of B dwarfs of well studied OB associations and Population I stars show a striking resemblance to abundances obtained for HD119608 in this study. This may imply a runaway status for the star.

Modeling wetland blackbird populations as a function of waterfowl abundance in the prairie pothole region of the United States and Canada

USGS Publications Warehouse

Forcey, G.M.; Linz, G.M.; Thogmartin, W.E.; Bleier, W.J.

2008-01-01

Blackbirds share wetland habitat with many waterfowl species in Bird Conservation Region 11 (BCR 11), the prairie potholes. Because of similar habitat preferences, there may be associations between blackbird populations and populations of one or more species of waterfowl in BCR11. This study models populations of red-winged blackbirds and yellow-headed blackbirds as a function of multiple waterfowl species using data from the North American Breeding Bird Survey within BCR11. For each blackbird species, we created a global model with blackbird abundance modeled as a function of 11 waterfowl species; nuisance effects (year, route, and observer) also were included in the model. Hierarchical Poisson regression models were fit using Markov chain Monte Carlo methods in WinBUGS 1.4.1. Waterfowl abundances were weakly associated with blackbird numbers, and no single waterfowl species showed a strong correlation with any blackbird species. These findings suggest waterfowl abundance from a single species is not likely a good bioindicator of blackbird abundance; however, a global model provided good fit for predicting red-winged blackbird abundance. Increased model complexity may be required for accurate predictions of blackbird abundance; the amount of data required to construct appropriate models may limit this approach for predicting blackbird abundance in the prairie potholes. Copyright ?? Taylor & Francis Group, LLC.

The Chemical Abundances of Stars in the Halo (CASH) Project. II. New Extremely Metal-poor Stars

NASA Astrophysics Data System (ADS)

Krugler, Julie A.; Frebel, A.; Roederer, I. U.; Sneden, C.; Shetrone, M.; Beers, T.; Christlieb, N.

2011-01-01

We present new abundance results from the Chemical Abundances of Stars in the Halo (CASH) project. The 500 CASH spectra were observed using the Hobby-Eberly Telescope in "snapshot" mode and are analyzed using an automated stellar parameter and abundance pipeline called CASHCODE. For the 20 most metal-poor stars of the CASH sample we have obtained high resolution spectra using the Magellan Telescope in order to test the uncertainties and systematic errors associated with the snapshot quality (i.e., R 15,000 and S/N 65) HET spectra and to calibrate the newly developed CASHCODE by making a detailed comparison between the stellar parameters and abundances determined from the high resolution and snapshot spectra. We find that the CASHCODE stellar parameters (effective temperature, surface gravity, metallicity, and microturbulence) agree well with the results of the manual analysis of the high resolution spectra. We present the abundances of three newly discovered stars with [Fe/H] < -3.5. For the entire pilot sample, we find typical halo abundance ratios with alpha-enhancement and Fe-peak depletion and a range of n-capture elements. The full CASH sample will be used to derive statistically robust abundance trends and frequencies (e.g. carbon and n-capture), as well as placing constraints on nucleosynthetic processes that occurred in the early universe.

Chemical abundances of globular clusters in NGC 5128 (Centaurus A)

NASA Astrophysics Data System (ADS)

Hernandez, Svea; Larsen, Søren; Trager, Scott; Kaper, Lex; Groot, Paul

2018-06-01

We perform a detailed abundance analysis on integrated-light spectra of 20 globular clusters (GCs) in the early-type galaxy NGC 5128 (Centaurus A). The GCs were observed with X-Shooter on the Very Large Telescope (VLT). The cluster sample spans a metallicity range of -1.92 < [Fe/H] < -0.13 dex. Using theoretical isochrones, we compute synthetic integrated-light spectra and iterate the individual abundances until the best fit to the observations is obtained. We measured abundances of Mg, Ca, and Ti, and find a slightly higher enhancement in NGC 5128 GCs with metallicities [Fe/H] < -0.75 dex, of the order of ˜0.1 dex, than in the average values observed in the Milky Way (MW) for GCs of the same metallicity. If this α-enhancement in the metal-poor GCs in NGC 5128 is genuine, it could hint at a chemical enrichment history different than that experienced by the MW. We also measure Na abundances in 9 out of 20 GCs. We find evidence for intracluster abundance variations in six of these clusters where we see enhanced [Na/Fe] > +0.25 dex. We obtain the first abundance measurements of Cr, Mn, and Ni for a sample of the GC population in NGC 5128 and find consistency with the overall trends observed in the MW, with a slight enhancement (<0.1 dex) in the Fe-peak abundances measured in the NGC 5128.

Monitoring Butterfly Abundance: Beyond Pollard Walks

PubMed Central

Pellet, Jérôme; Bried, Jason T.; Parietti, David; Gander, Antoine; Heer, Patrick O.; Cherix, Daniel; Arlettaz, Raphaël

2012-01-01

Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability. PMID:22859980

Observations on changes in abundance of questing Ixodes ricinus, castor bean tick, over a 35-year period in the eastern part of its range (Russia, Tula region).

PubMed

Korotkov, Yu; Kozlova, T; Kozlovskaya, L

2015-06-01

Ixodes ricinus (Acari: Ixodidae) L. transmit a wide variety of pathogens to vertebrates including viruses, bacteria and protozoa. Understanding of the epidemiology of tick-borne infections requires basic knowledge of the regional and local factors influencing tick population dynamics. The present study describes the results of monitoring of a questing I. ricinus population, conducted over 35 years (1977-2011) in the eastern, poorly studied part of its range (Russia, Tula region). We have found that the multiannual average abundance of ticks is small and varies depending on the biotope and degree of urban transformation. Tick abundance for the first 14 years of observations (1977-1990) was at the lower limit of the sensitivity of our methods throughout the study area (0.1-0.9 specimens per 1-km transect). In the following 21 years (1991-2011), a manifold increase in abundance was observed, which reached 18.1 ± 1.8 individuals per 1-km transect in moist floodplain terraces, and 4.8 ± 0.9 in xerophylic hill woods. Long-term growth of tick abundance occurred in spite of a relatively constant abundance of small mammals and only minor fluctuations in the abundance of large wild animals. Climate and anthropogenic changes appear to be the main contributors to increased abundance of the tick. © 2015 The Royal Entomological Society.

IDENTIFICATION OF NEODYMIUM IN THE APOGEE H -BAND SPECTRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasselquist, Sten; Holtzman, Jon; Chojnowski, Drew

2016-12-10

We present the detection of 10 lines of singly ionized neodymium (Nd ii, Z  = 60) in H -band spectra using observations from the SDSS-III Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. These lines were detected in a metal-poor ([Fe/H] ∼ −1.5), neutron-capture element-enhanced star recently discovered in the APOGEE sample. Using an optical high-resolution spectrum, we derive a Nd abundance for this star using Nd ii lines with precise, laboratory-derived gf values. This optical abundance is used to derive log( gf ) values for the H -band lines. We use these lines to rederive Nd ii abundances for two more metal-rich, s -process enhancedmore » stars observed by APOGEE and find that these lines yield consistent Nd ii abundances, confirming the Nd enhancement of these stars. We explore the region of parameter space in the APOGEE sample over which these lines can be used to measure Nd ii abundances. We find that Nd abundances can be reliably derived for ∼18% of the red giants observed by APOGEE. This will result in ∼50,000 Milky Way stars with Nd ii abundances following the conclusion of APOGEE-2, allowing for studies of neutron-capture element abundance distributions across the entire Milky Way.« less

Advancing the use of local ecological knowledge for assessing data-poor species in coastal ecosystems.

PubMed

Beaudreau, Anne H; Levin, Phillip S

2014-03-01

Many of the world's most vulnerable and rapidly changing ecosystems are also among the most data-poor, leading to an increased interest in use of local ecological knowledge (LEK) to document long-term environmental change. The integration of multiple knowledge sources for assessing species abundance and distribution has gained traction over the past decade as a growing number of case studies show concordance between LEK and scientific data. This study advances the use of quantitative approaches for synthesizing LEK by presenting a novel application of bootstrapping and statistical modeling to evaluate variance in ecological observations of fisheries practitioners. We developed an historical record of abundance for 22 marine species in Puget Sound, Washington (USA), using LEK, and we quantified variation in perceptions of abundance trends among fishers, divers, and researchers. These individuals differed in aspects of their information environments, which are characterized by how, when, and where an individual has acquired ecological information. Abundance trends derived from interviews suggest that populations of long-lived rockfishes (Sebastes spp.) have been in decline since at least the 1960s and that three rockfishes protected under the Endangered Species Act were perceived as relatively less abundant than other species. Differences in perception of rockfish abundance trends among age groups were consistent with our hypothesis that the reported magnitude of decline in abundance would increase with age, with younger respondents more likely to report high abundance than older individuals across all periods. Temporal patterns in the mean and variance of reported rockfish abundance indices were qualitatively similar between fishers and researchers; however, fishers reported higher indices of abundance than researchers for all but one rockfish species. The two respondent groups reported similar changes in rockfish abundance from the 1940s to 2000s, except for two recreationally valuable species that fishers perceived as having undergone greater declines than perceived by researchers. When aggregated at appropriate spatial-temporal scales and in a culturally appropriate manner, observations of resource users are a valuable source of ecological information. Continued development of creative analytical tools for synthesizing multiple knowledge sources will be essential for advancing the formal use of LEK in assessments of marine species.

Occupancy and abundance of wintering birds in a dynamic agricultural landscape

USGS Publications Warehouse

Miller, Mark W.; Pearlstine, Elise V.; Dorazio, Robert M.; Mazzotti, Frank J.

2011-01-01

Assessing wildlife management action requires monitoring populations, and abundance often is the parameter monitored. Recent methodological advances have enabled estimation of mean abundance within a habitat using presence–absence or count data obtained via repeated visits to a sample of sites. These methods assume populations are closed and intuitively assume habitats within sites change little during a field season. However, many habitats are highly variable over short periods. We developed a variation of existing occupancy and abundance models that allows for extreme spatio-temporal differences in habitat, and resulting changes in wildlife abundance, among sites and among visits to a site within a field season. We conducted our study in sugarcane habitat within the Everglades Agricultural Area southeast of Lake Okeechobee in south Florida. We counted wintering birds, primarily passerines, within 245 sites usually 5 times at each site during December 2006–March 2007. We estimated occupancy and mean abundance of birds in 6 vegetation states during the sugarcane harvest and allowed these parameters to vary temporally or spatially within a vegetation state. Occupancy and mean abundance of the common yellowthroat (Geothlypis trichas) was affected by structure of sugarcane and uncultivated edge vegetation (occupancy=1.00 [95%CĪ=0.96–1.00] and mean abundance=7.9 [95%CĪ=3.2–19.5] in tall sugarcane with tall edge vegetation versus 0.20 [95%CĪ=0.04–0.71] and 0.22 [95%CĪ=0.04–1.2], respectively, in short sugarcane with short edge vegetation in one half of the study area). Occupancy and mean abundance of palm warblers (Dendroica palmarum) were constant (occupancy=1.00, 95%CĪ=0.69–1.00; mean abundance=18, 95%CĪ=1–270). Our model may enable wildlife managers to assess rigorously effects of future edge habitat management on avian distribution and abundance within agricultural landscapes during winter or the breeding season. The model may also help wildlife managers make similar management decisions involving other dynamic habitats such as wetlands, prairies, and even forested areas if forest management or fires occur during the field season.

Occupancy and abundance of wintering birds in a dynamic agricultural landscape

USGS Publications Warehouse

Miller, M.W.; Pearlstine, E.V.; Dorazio, R.M.; Mazzotti, F.J.

2011-01-01

Assessing wildlife management action requires monitoring populations, and abundance often is the parameter monitored. Recent methodological advances have enabled estimation of mean abundance within a habitat using presence-absence or count data obtained via repeated visits to a sample of sites. These methods assume populations are closed and intuitively assume habitats within sites change little during a field season. However, many habitats are highly variable over short periods. We developed a variation of existing occupancy and abundance models that allows for extreme spatio-temporal differences in habitat, and resulting changes in wildlife abundance, among sites and among visits to a site within a field season. We conducted our study in sugarcane habitat within the Everglades Agricultural Area southeast of Lake Okeechobee in south Florida. We counted wintering birds, primarily passerines, within 245 sites usually 5 times at each site during December 2006-March 2007. We estimated occupancy and mean abundance of birds in 6 vegetation states during the sugarcane harvest and allowed these parameters to vary temporally or spatially within a vegetation state. Occupancy and mean abundance of the common yellowthroat (Geothlypis trichas) was affected by structure of sugarcane and uncultivated edge vegetation (occupancy = 1.00 [95%C?? = 0.96-1.00] and mean abundance = 7.9 [95%C?? = 3.2-19.5] in tall sugarcane with tall edge vegetation versus 0.20 [95%C?? = 0.04-0.71] and 0.22 [95%C?? = 0.04-1.2], respectively, in short sugarcane with short edge vegetation in one half of the study area). Occupancy and mean abundance of palm warblers (Dendroica palmarum) were constant (occupancy = 1.00, 95%C?? = 0.69-1.00; mean abundance = 18, 95%C?? = 1-270). Our model may enable wildlife managers to assess rigorously effects of future edge habitat management on avian distribution and abundance within agricultural landscapes during winter or the breeding season. The model may also help wildlife managers make similar management decisions involving other dynamic habitats such as wetlands, prairies, and even forested areas if forest management or fires occur during the field season. ?? 2011 The Wildlife Society.

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 depth. In general, faunal similarity is expected to decrease as separation distance increases, but unexpectedly, the northern- and southern-region faunas were more similar to each other than to the central-region fauna. Kinorhynchs were most responsible for this pattern.

Inferring invasive species abundance using removal data from management actions.

PubMed

Davis, Amy J; Hooten, Mevin B; Miller, Ryan S; Farnsworth, Matthew L; Lewis, Jesse; Moxcey, Michael; Pepin, Kim M

2016-10-01

Evaluation of the progress of management programs for invasive species is crucial for demonstrating impacts to stakeholders and strategic planning of resource allocation. Estimates of abundance before and after management activities can serve as a useful metric of population management programs. However, many methods of estimating population size are too labor intensive and costly to implement, posing restrictive levels of burden on operational programs. Removal models are a reliable method for estimating abundance before and after management using data from the removal activities exclusively, thus requiring no work in addition to management. We developed a Bayesian hierarchical model to estimate abundance from removal data accounting for varying levels of effort, and used simulations to assess the conditions under which reliable population estimates are obtained. We applied this model to estimate site-specific abundance of an invasive species, feral swine (Sus scrofa), using removal data from aerial gunning in 59 site/time-frame combinations (480-19,600 acres) throughout Oklahoma and Texas, USA. Simulations showed that abundance estimates were generally accurate when effective removal rates (removal rate accounting for total effort) were above 0.40. However, when abundances were small (<50) the effective removal rate needed to accurately estimates abundances was considerably higher (0.70). Based on our post-validation method, 78% of our site/time frame estimates were accurate. To use this modeling framework it is important to have multiple removals (more than three) within a time frame during which demographic changes are minimized (i.e., a closed population; ≤3 months for feral swine). Our results show that the probability of accurately estimating abundance from this model improves with increased sampling effort (8+ flight hours across the 3-month window is best) and increased removal rate. Based on the inverse relationship between inaccurate abundances and inaccurate removal rates, we suggest auxiliary information that could be collected and included in the model as covariates (e.g., habitat effects, differences between pilots) to improve accuracy of removal rates and hence abundance estimates. © 2016 by the Ecological Society of America.

Environmental drivers of Ixodes ricinus abundance in forest fragments of rural European landscapes.

PubMed

Ehrmann, Steffen; Liira, Jaan; Gärtner, Stefanie; Hansen, Karin; Brunet, Jörg; Cousins, Sara A O; Deconchat, Marc; Decocq, Guillaume; De Frenne, Pieter; De Smedt, Pallieter; Diekmann, Martin; Gallet-Moron, Emilie; Kolb, Annette; Lenoir, Jonathan; Lindgren, Jessica; Naaf, Tobias; Paal, Taavi; Valdés, Alicia; Verheyen, Kris; Wulf, Monika; Scherer-Lorenzen, Michael

2017-09-06

The castor bean tick (Ixodes ricinus) transmits infectious diseases such as Lyme borreliosis, which constitutes an important ecosystem disservice. Despite many local studies, a comprehensive understanding of the key drivers of tick abundance at the continental scale is still lacking. We analyze a large set of environmental factors as potential drivers of I. ricinus abundance. Our multi-scale study was carried out in deciduous forest fragments dispersed within two contrasting rural landscapes of eight regions, along a macroclimatic gradient stretching from southern France to central Sweden and Estonia. We surveyed the abundance of I. ricinus, plant community composition, forest structure and soil properties and compiled data on landscape structure, macroclimate and habitat properties. We used linear mixed models to analyze patterns and derived the relative importance of the significant drivers. Many drivers had, on their own, either a moderate or small explanatory value for the abundance of I. ricinus, but combined they explained a substantial part of variation. This emphasizes the complex ecology of I. ricinus and the relevance of environmental factors for tick abundance. Macroclimate only explained a small fraction of variation, while properties of macro- and microhabitat, which buffer macroclimate, had a considerable impact on tick abundance. The amount of forest and the composition of the surrounding rural landscape were additionally important drivers of tick abundance. Functional (dispersules) and structural (density of tree and shrub layers) properties of the habitat patch played an important role. Various diversity metrics had only a small relative importance. Ontogenetic tick stages showed pronounced differences in their response. The abundance of nymphs and adults is explained by the preceding stage with a positive relationship, indicating a cumulative effect of drivers. Our findings suggest that the ecosystem disservices of tick-borne diseases, via the abundance of ticks, strongly depends on habitat properties and thus on how humans manage ecosystems from the scale of the microhabitat to the landscape. This study stresses the need to further evaluate the interaction between climate change and ecosystem management on I. ricinus abundance.

The solar photospheric abundance of hafnium and thorium. Results from CO5BOLD 3D hydrodynamic model atmospheres

NASA Astrophysics Data System (ADS)

Caffau, E.; Sbordone, L.; Ludwig, H.-G.; Bonifacio, P.; Steffen, M.; Behara, N. T.

2008-05-01

Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a CO5BOLD 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Methods: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf) = 0.87 ± 0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th II 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of a Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th) = 0.08 ± 0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has a non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.

Local and cross-seasonal associations of climate and land use with abundance of monarch butterflies Danaus plexippus

USGS Publications Warehouse

Saunders, Sarah P.; Ries, Leslie; Oberhasuer, Karen S.; Thogmartin, Wayne E.; Zipkin, Elise F.

2017-01-01

Quantifying how climate and land use factors drive population dynamics at regional scales is complex because it depends on the extent of spatial and temporal synchrony among local populations, and the integration of population processes throughout a species’ annual cycle. We modeled weekly, site-specific summer abundance (1994–2013) of monarch butterflies Danaus plexippus at sites across Illinois, USA to assess relative associations of monarch abundance with climate and land use variables during the winter, spring, and summer stages of their annual cycle. We developed negative binomial regression models to estimate monarch abundance during recruitment in Illinois as a function of local climate, site-specific crop cover, and county-level herbicide (glyphosate) application. We also incorporated cross-seasonal covariates, including annual abundance of wintering monarchs in Mexico and climate conditions during spring migration and breeding in Texas, USA. We provide the first empirical evidence of a negative association between county-level glyphosate application and local abundance of adult monarchs, particularly in areas of concentrated agriculture. However, this association was only evident during the initial years of the adoption of herbicide-resistant crops (1994–2003). We also found that wetter and, to a lesser degree, cooler springs in Texas were associated with higher summer abundances in Illinois, as were relatively cool local summer temperatures in Illinois. Site-specific abundance of monarchs averaged approximately one fewer per site from 2004–2013 than during the previous decade, suggesting a recent decline in local abundance of monarch butterflies on their summer breeding grounds in Illinois. Our results demonstrate that seasonal climate and land use are associated with trends in adult monarch abundance, and our approach highlights the value of considering fine-resolution temporal fluctuations in population-level responses to environmental conditions when inferring the dynamics of migratory species.

Predicting the Dynamics of Protein Abundance

PubMed Central

Mehdi, Ahmed M.; Patrick, Ralph; Bailey, Timothy L.; Bodén, Mikael

2014-01-01

Protein synthesis is finely regulated across all organisms, from bacteria to humans, and its integrity underpins many important processes. Emerging evidence suggests that the dynamic range of protein abundance is greater than that observed at the transcript level. Technological breakthroughs now mean that sequencing-based measurement of mRNA levels is routine, but protocols for measuring protein abundance remain both complex and expensive. This paper introduces a Bayesian network that integrates transcriptomic and proteomic data to predict protein abundance and to model the effects of its determinants. We aim to use this model to follow a molecular response over time, from condition-specific data, in order to understand adaptation during processes such as the cell cycle. With microarray data now available for many conditions, the general utility of a protein abundance predictor is broad. Whereas most quantitative proteomics studies have focused on higher organisms, we developed a predictive model of protein abundance for both Saccharomyces cerevisiae and Schizosaccharomyces pombe to explore the latitude at the protein level. Our predictor primarily relies on mRNA level, mRNA–protein interaction, mRNA folding energy and half-life, and tRNA adaptation. The combination of key features, allowing for the low certainty and uneven coverage of experimental observations, gives comparatively minor but robust prediction accuracy. The model substantially improved the analysis of protein regulation during the cell cycle: predicted protein abundance identified twice as many cell-cycle-associated proteins as experimental mRNA levels. Predicted protein abundance was more dynamic than observed mRNA expression, agreeing with experimental protein abundance from a human cell line. We illustrate how the same model can be used to predict the folding energy of mRNA when protein abundance is available, lending credence to the emerging view that mRNA folding affects translation efficiency. The software and data used in this research are available at http://bioinf.scmb.uq.edu.au/proteinabundance/. PMID:24532840

Predicting the dynamics of protein abundance.

PubMed

Mehdi, Ahmed M; Patrick, Ralph; Bailey, Timothy L; Bodén, Mikael

2014-05-01

Protein synthesis is finely regulated across all organisms, from bacteria to humans, and its integrity underpins many important processes. Emerging evidence suggests that the dynamic range of protein abundance is greater than that observed at the transcript level. Technological breakthroughs now mean that sequencing-based measurement of mRNA levels is routine, but protocols for measuring protein abundance remain both complex and expensive. This paper introduces a Bayesian network that integrates transcriptomic and proteomic data to predict protein abundance and to model the effects of its determinants. We aim to use this model to follow a molecular response over time, from condition-specific data, in order to understand adaptation during processes such as the cell cycle. With microarray data now available for many conditions, the general utility of a protein abundance predictor is broad. Whereas most quantitative proteomics studies have focused on higher organisms, we developed a predictive model of protein abundance for both Saccharomyces cerevisiae and Schizosaccharomyces pombe to explore the latitude at the protein level. Our predictor primarily relies on mRNA level, mRNA-protein interaction, mRNA folding energy and half-life, and tRNA adaptation. The combination of key features, allowing for the low certainty and uneven coverage of experimental observations, gives comparatively minor but robust prediction accuracy. The model substantially improved the analysis of protein regulation during the cell cycle: predicted protein abundance identified twice as many cell-cycle-associated proteins as experimental mRNA levels. Predicted protein abundance was more dynamic than observed mRNA expression, agreeing with experimental protein abundance from a human cell line. We illustrate how the same model can be used to predict the folding energy of mRNA when protein abundance is available, lending credence to the emerging view that mRNA folding affects translation efficiency. The software and data used in this research are available at http://bioinf.scmb.uq.edu.au/proteinabundance/.

Reduced hornbill abundance associated with low seed arrival and altered recruitment in a hunted and logged tropical forest.

PubMed

Naniwadekar, Rohit; Shukla, Ushma; Isvaran, Kavita; Datta, Aparajita

2015-01-01

Logging and hunting are two key direct threats to the survival of wildlife in the tropics, and also disrupt important ecosystem processes. We investigated the impacts of these two factors on the different stages of the seed dispersal cycle, including abundance of plants and their dispersers and dispersal of seeds and recruitment, in a tropical forest in north-east India. We focused on hornbills, which are important seed dispersers in these forests, and their food tree species. We compared abundances of hornbill food tree species in a site with high logging and hunting pressures (heavily disturbed) with a site that had no logging and relatively low levels of hunting (less disturbed) to understand logging impacts on hornbill food tree abundance. We compared hornbill abundances across these two sites. We, then, compared the scatter-dispersed seed arrival of five large-seeded tree species and the recruitment of four of those species. Abundances of hornbill food trees that are preferentially targeted by logging were two times higher in the less disturbed site as compared to the heavily disturbed site while that of hornbills was 22 times higher. The arrival of scatter-dispersed seeds was seven times higher in the less disturbed site. Abundances of recruits of two tree species were significantly higher in the less disturbed site. For another species, abundances of younger recruits were significantly lower while that of older recruits were higher in the heavily disturbed site. Our findings suggest that logging reduces food plant abundance for an important frugivore-seed disperser group, while hunting diminishes disperser abundances, with an associated reduction in seed arrival and altered recruitment of animal-dispersed tree species in the disturbed site. Based on our results, we present a conceptual model depicting the relationships and pathways between vertebrate-dispersed trees, their dispersers, and the impacts of hunting and logging on these pathways.

Reduced Hornbill Abundance Associated with Low Seed Arrival and Altered Recruitment in a Hunted and Logged Tropical Forest

PubMed Central

Naniwadekar, Rohit; Shukla, Ushma; Isvaran, Kavita; Datta, Aparajita

2015-01-01

Logging and hunting are two key direct threats to the survival of wildlife in the tropics, and also disrupt important ecosystem processes. We investigated the impacts of these two factors on the different stages of the seed dispersal cycle, including abundance of plants and their dispersers and dispersal of seeds and recruitment, in a tropical forest in north-east India. We focused on hornbills, which are important seed dispersers in these forests, and their food tree species. We compared abundances of hornbill food tree species in a site with high logging and hunting pressures (heavily disturbed) with a site that had no logging and relatively low levels of hunting (less disturbed) to understand logging impacts on hornbill food tree abundance. We compared hornbill abundances across these two sites. We, then, compared the scatter-dispersed seed arrival of five large-seeded tree species and the recruitment of four of those species. Abundances of hornbill food trees that are preferentially targeted by logging were two times higher in the less disturbed site as compared to the heavily disturbed site while that of hornbills was 22 times higher. The arrival of scatter-dispersed seeds was seven times higher in the less disturbed site. Abundances of recruits of two tree species were significantly higher in the less disturbed site. For another species, abundances of younger recruits were significantly lower while that of older recruits were higher in the heavily disturbed site. Our findings suggest that logging reduces food plant abundance for an important frugivore-seed disperser group, while hunting diminishes disperser abundances, with an associated reduction in seed arrival and altered recruitment of animal-dispersed tree species in the disturbed site. Based on our results, we present a conceptual model depicting the relationships and pathways between vertebrate-dispersed trees, their dispersers, and the impacts of hunting and logging on these pathways. PMID:25781944

Multidirectional abundance shifts among North American birds and the relative influence of multifaceted climate factors.

PubMed

Huang, Qiongyu; Sauer, John R; Dubayah, Ralph O

2017-09-01

Shifts in species distributions are major fingerprint of climate change. Examining changes in species abundance structures at a continental scale enables robust evaluation of climate change influences, but few studies have conducted these evaluations due to limited data and methodological constraints. In this study, we estimate temporal changes in abundance from North American Breeding Bird Survey data at the scale of physiographic strata to examine the relative influence of different components of climatic factors and evaluate the hypothesis that shifting species distributions are multidirectional in resident bird species in North America. We quantify the direction and velocity of the abundance shifts of 57 permanent resident birds over 44 years using a centroid analysis. For species with significant abundance shifts in the centroid analysis, we conduct a more intensive correlative analysis to identify climate components most strongly associated with composite change of abundance within strata. Our analysis focus on two contrasts: the relative importance of climate extremes vs. averages, and of temperature vs. precipitation in strength of association with abundance change. Our study shows that 36 species had significant abundance shifts over the study period. The average velocity of the centroid is 5.89 km·yr -1 . The shifted distance on average covers 259 km, 9% of range extent. Our results strongly suggest that the climate change fingerprint in studied avian distributions is multidirectional. Among 6 directions with significant abundance shifts, the northwestward shift was observed in the largest number of species (n = 13). The temperature/average climate model consistently has greater predictive ability than the precipitation/extreme climate model in explaining strata-level abundance change. Our study shows heterogeneous avian responses to recent environmental changes. It highlights needs for more species-specific approaches to examine contributing factors to recent distributional changes and for comprehensive conservation planning for climate change adaptation. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Calibrating abundance indices with population size estimators of red back salamanders (Plethodon cinereus) in a New England forest

PubMed Central

Ellison, Aaron M.; Jackson, Scott

2015-01-01

Herpetologists and conservation biologists frequently use convenient and cost-effective, but less accurate, abundance indices (e.g., number of individuals collected under artificial cover boards or during natural objects surveys) in lieu of more accurate, but costly and destructive, population size estimators to detect and monitor size, state, and trends of amphibian populations. Although there are advantages and disadvantages to each approach, reliable use of abundance indices requires that they be calibrated with accurate population estimators. Such calibrations, however, are rare. The red back salamander, Plethodon cinereus, is an ecologically useful indicator species of forest dynamics, and accurate calibration of indices of salamander abundance could increase the reliability of abundance indices used in monitoring programs. We calibrated abundance indices derived from surveys of P. cinereus under artificial cover boards or natural objects with a more accurate estimator of their population size in a New England forest. Average densities/m2 and capture probabilities of P. cinereus under natural objects or cover boards in independent, replicate sites at the Harvard Forest (Petersham, Massachusetts, USA) were similar in stands dominated by Tsuga canadensis (eastern hemlock) and deciduous hardwood species (predominantly Quercus rubra [red oak] and Acer rubrum [red maple]). The abundance index based on salamanders surveyed under natural objects was significantly associated with density estimates of P. cinereus derived from depletion (removal) surveys, but underestimated true density by 50%. In contrast, the abundance index based on cover-board surveys overestimated true density by a factor of 8 and the association between the cover-board index and the density estimates was not statistically significant. We conclude that when calibrated and used appropriately, some abundance indices may provide cost-effective and reliable measures of P. cinereus abundance that could be used in conservation assessments and long-term monitoring at Harvard Forest and other northeastern USA forests. PMID:26020008

A broad assessment of factors determining Culicoides imicola abundance: modelling the present and forecasting its future in climate change scenarios.

PubMed

Acevedo, Pelayo; Ruiz-Fons, Francisco; Estrada, Rosa; Márquez, Ana Luz; Miranda, Miguel Angel; Gortázar, Christian; Lucientes, Javier

2010-12-06

Bluetongue (BT) is still present in Europe and the introduction of new serotypes from endemic areas in the African continent is a possible threat. Culicoides imicola remains one of the most relevant BT vectors in Spain and research on the environmental determinants driving its life cycle is key to preventing and controlling BT. Our aim was to improve our understanding of the biotic and abiotic determinants of C. imicola by modelling its present abundance, studying the spatial pattern of predicted abundance in relation to BT outbreaks, and investigating how the predicted current distribution and abundance patterns might change under future (2011-2040) scenarios of climate change according to the Intergovernmental Panel on Climate Change. C. imicola abundance data from the bluetongue national surveillance programme were modelled with spatial, topoclimatic, host and soil factors. The influence of these factors was further assessed by variation partitioning procedures. The predicted abundance of C. imicola was also projected to a future period. Variation partitioning demonstrated that the pure effect of host and topoclimate factors explained a high percentage (>80%) of the variation. The pure effect of soil followed in importance in explaining the abundance of C. imicola. A close link was confirmed between C. imicola abundance and BT outbreaks. To the best of our knowledge, this study is the first to consider wild and domestic hosts in predictive modelling for an arthropod vector. The main findings regarding the near future show that there is no evidence to suggest that there will be an important increase in the distribution range of C. imicola; this contrasts with an expected increase in abundance in the areas where it is already present in mainland Spain. What may be expected regarding the future scenario for orbiviruses in mainland Spain, is that higher predicted C. imicola abundance may significantly change the rate of transmission of orbiviruses.

Synchronous centennial-scale variability in abundance of remote sardine populations in the Pacific

NASA Astrophysics Data System (ADS)

Kuwae, M.; Takashige, S.; Yamamoto, M.; Sagawa, T.; Takeoka, H.

2012-12-01

A number of studies have identified evidence for connections between Pacific climate decadal variability and variations in Pacific marine ecosystems which are typically shown in abundance of remote sardine and anchovy species off Japan, California, Peru, and Chile as well as Alaska salmon species. The variations in climate indices and abundance of sardine and anchovy species most likely have 50-70 year cycles and therefore these natural perturbations in climates and Pacific ecosystems should be considered for developing predictive models of fisheries productions and the managements. Despite the importance of natural perturbations for long-term predictions, one issue, whether synchronous centennial-variations in remote Pacific fisheries productions in response to climate variability exists in the past, has not been questioned, because there has never been long-term reconstructed time series in the western North Pacific. Here we present well preserved, fossil fish scale-based abundance record of Japanese sardine over the last 1100 years reconstructed from a seasonal anoxic basin in the western Seto Inland Sea near their spawning areas in the western North Pacific. A comparison of our record with other previous records clearly showed centennial-scale variations in abundance of sardine species off Japan, California, and Chile, characterized by centennial-scale alternations between low abundance regimes and high abundance regimes in which multidecadal fluctuations with large amplitudes occurred once or several times. High abundance regimes from 1450 to 1650 AD and after 1800 AD and a low abundance regime from 1650 to 1800 AD corresponded to low frequency patterns of PDO index reconstructed from tree-ring records in North America. This indicates that connections between Pacific climate variability and variations in Pacific marine ecosystems exist not only on multidecadal timescales but on centennial timescales. Three to four hundred-yr periodicity of the Pacific climate-ecosystem dynamics suggests possibility of a change into a century-long, low sardine abundance regime in the next 100 years.

Oxygen abundances in halo giants. I - Giants in the very metal-poor globular clusters M92 and M15 and the metal-poor halo field

NASA Astrophysics Data System (ADS)

Sneden, Christopher; Kraft, Robert P.; Prosser, Charles F.; Langer, G. E.

1991-12-01

Oxygen, iron, vanadium, and scandium abundances are derived for very metal-poor giants in the globular clusters M92 and M15, and giants of comparable metallicity in the local halo field. The forbidden O I line dublet (6300, 6363) and nearby metallic lines in spectra are analyzed using line analysis and spectral synthesis codes. The Fe/H abundance for M92 is estimated at -2.25 +/-0.02 based on nine giants with a range of 500 K in effective temperature. No evidence for star-to-star variations in the Fe/H abundance was found. O-rich and O-poor stars appear intermixed in the H-R diagram. O - N nuclear synthesis and mixing to the surface are proposed as the best explanation for the low-oxygen giants. The nitrogen abundances obtained earlier for nine of the ten halo field giants in this sample are incompatible with the very large nitrogen abundances expected of the O/Fe abundance of about + 1.2 in halo field subdwarfs, as found by Abia and Rebolo (1989), and not more than 0.6 in halo giants, as found in this and other studies.

Forest edge disturbance increases rattan abundance in tropical rain forest fragments.

PubMed

Campbell, Mason J; Edwards, Will; Magrach, Ainhoa; Laurance, Susan G; Alamgir, Mohammed; Porolak, Gabriel; Laurance, William F

2017-07-20

Human-induced forest fragmentation poses one of the largest threats to global diversity yet its impact on rattans (climbing palms) has remained virtually unexplored. Rattan is arguably the world's most valuable non-timber forest product though current levels of harvesting and land-use change place wild populations at risk. To assess rattan response to fragmentation exclusive of harvesting impacts we examined rattan abundance, demography and ecology within the forests of northeastern, Australia. We assessed the community abundance of rattans, and component adult (>3 m) and juvenile (≤3 m) abundance in five intact forests and five fragments (23-58 ha) to determine their response to a range of environmental and ecological parameters. Fragmented forests supported higher abundances of rattans than intact forests. Fragment size and edge degradation significantly increased adult rattan abundance, with more in smaller fragments and near edges. Our findings suggest that rattan increase within fragments is due to canopy disturbance of forest edges resulting in preferential, high-light habitat. However, adult and juvenile rattans may respond inconsistently to fragmentation. In managed forest fragments, a rattan abundance increase may provide economic benefits through sustainable harvesting practices. However, rattan increases in protected area forest fragments could negatively impact conservation outcomes.

Species abundance and potential biological control services in shade vs. sun coffee in Puerto Rico

USGS Publications Warehouse

Borkhataria, Rena R.; Collazo, Jaime A.; Groom, Martha J.

2012-01-01

Birds, lizards and insects were surveyed in three sun and three shade coffee plantations in Puerto Rico to provide a comprehensive comparison of biodiversity between plantations types and to identify potential interrelationships (e.g., biological or natural control services) between members of each taxon and coffee pests. Abundance of avian species, including insectivorous species, was significantly higher in shade coffee. Anolis cristatellus and A. stratulus were significantly more abundant in sun plantations whereas A. gundlachi and A. evermanni were detected more frequently in shade plantations. Insects in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, and Psocoptera were significantly more abundant in shade coffee, while orthopterans were more abundant in sun. The coffee leaf miner (Leucoptera coffeela) and the flatid planthopper (Petrusa epilepsis) did not differ significantly between plantation types, nor did the abundance of the wasp complex that parasitizes the coffee leaf miner. These findings confirmed that shade plantations harbor a wide array of elements of biodiversity; but sun plantations may also harbor many elements of biodiversity, and in some cases, in higher abundance than in shade plantations.

Exact theory of freeze-out

NASA Astrophysics Data System (ADS)

Cannoni, Mirco

2015-03-01

We show that the standard theory of thermal production and chemical decoupling of WIMPs is incomplete. The hypothesis that WIMPs are produced and decouple from a thermal bath implies that the rate equation the bath particles interacting with the WIMPs is an algebraic equation that constraints the actual WIMPs abundance to have a precise analytical form down to the temperature . The point , which coincides with the stationary point of the equation for the quantity , is where the maximum departure of the WIMPs abundance from the thermal value is reached. For each mass and total annihilation cross section , the temperature and the actual WIMPs abundance are exactly known. This value provides the true initial condition for the usual differential equation that have to be integrated in the interval . The matching of the two abundances at is continuous and differentiable. The dependence of the present relic abundance on the abundance at an intermediate temperature is an exact result. The exact theory suggests a new analytical approximation that furnishes the relic abundance accurate at the level of 1-2 % in the case of -wave and -wave scattering cross sections. We conclude the paper studying the evolution of the WIMPs chemical potential and the entropy production using methods of non-equilibrium thermodynamics.

The isotropic condition of energetic particles emitted from a large solar flare. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Spalding, J.

1983-01-01

Isotope abundance ratios for 5 to 50 MeV/nuc nuclei from a large solar flare were measured. The measurements were made by the heavy isotope spectrometer telescope (HIST) on the ISEE-3 satellite orbiting the Sun near an Earth-Sun liberation point approximately one million miles sunward of the Earth. Finite values for the isotope abundance ratios C-13/C-12, N-15/N-14, O-18/O-16, Ne-22/Ne-20, Mg-25/Mg-24, and Mg-26/Mg-24, and upper limits for the isotope abundance ratios He-3/He-4, C-14/C-12, O-17/O-16 and Ne-21/Ne-20 were reported. Element abundances and spectra were measured to compare the flare with other reported flares. The flare is a typical large flare with low Fe/O abundance or = to 0.1). For C-13/C-12, N-15/N-14, O-18/O-16, Mg-25/Mg-24 and Mg-26/Mg-24 isotope abundance ratios agree with the solar system abundance ratios. Measurement for Ne-22/Ne-20 agree with the isotopic composition of the meteoritic component neon-A.

Modeling unobserved sources of heterogeneity in animal abundance using a Dirichlet process prior

USGS Publications Warehouse

Dorazio, R.M.; Mukherjee, B.; Zhang, L.; Ghosh, M.; Jelks, H.L.; Jordan, F.

2008-01-01

In surveys of natural populations of animals, a sampling protocol is often spatially replicated to collect a representative sample of the population. In these surveys, differences in abundance of animals among sample locations may induce spatial heterogeneity in the counts associated with a particular sampling protocol. For some species, the sources of heterogeneity in abundance may be unknown or unmeasurable, leading one to specify the variation in abundance among sample locations stochastically. However, choosing a parametric model for the distribution of unmeasured heterogeneity is potentially subject to error and can have profound effects on predictions of abundance at unsampled locations. In this article, we develop an alternative approach wherein a Dirichlet process prior is assumed for the distribution of latent abundances. This approach allows for uncertainty in model specification and for natural clustering in the distribution of abundances in a data-adaptive way. We apply this approach in an analysis of counts based on removal samples of an endangered fish species, the Okaloosa darter. Results of our data analysis and simulation studies suggest that our implementation of the Dirichlet process prior has several attractive features not shared by conventional, fully parametric alternatives. ?? 2008, The International Biometric Society.

Response of slimy sculpins to predation by juvenile lake trout in southern Lake Ontario

USGS Publications Warehouse

Owens, Randall W.; Bergstedt, Roger A.

1994-01-01

Abundance and biomass of slimy sculpin Cottus cognatus declined in Lake Ontario at depths most frequently occupied by juvenile lake trout Salvelinus namaycush (<70 m), but not at greater depths, during 1980–1987. The abundance of juvenile lake trout increased at depths less than 70 m between 1980 and 1987, and slimy sculpin abundance was negatively correlated with lake trout abundance. The size of slimy sculpins caught at depths less than 70 m decreased between 1980 and 1987, fish 50–99 mm becoming less common and fish 100 mm or longer becoming rare. The size of slimy sculpins at depths greater than 70 m did not change, Because slimy sculpins are the principal fish eaten by juvenile lake trout, and because juvenile lake trout were most abundant at depths where the greatest changes in the slimy sculpin population took place, we conclude that juvenile lake trout in Lake Ontario altered the slimy sculpin population. No significant negative correlations were found between abundance of slimy sculpins and those of the two most abundant fishes in Lake Ontario: Alewife Alosa pseudoharengus and rainbow smeltOsmerus mordax.

Impact of Grassland Reseeding, Herbicide Spraying and Ploughing on Diversity and Abundance of Soil Arthropods.

PubMed

Liu, Wei; Zhang, Junling; Norris, Stuart L; Murray, Philip J

2016-01-01

In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: (1) before chemical herbicide spray; (2) after spray but before ploughing; (3) after ploughing but before reseeding; and (4) after 1 year of recovery. Our results demonstrate that, Acari and Collembola were the two soil fauna taxa with the highest abundance and accounted for around 96% of the relative total abundance among the various managements. Herbicide application tended to increase soil invertebrate abundance. Conversely, subsequent ploughing significantly reduced soil invertebrate abundance and had an obvious negative effect on soil primary and secondary decomposers, which were mainly due to the variations of Acari (especially Oribatida) and Coleoptera group abundance. Moreover, reseeding also reduced the individual number of the groups mentioned above, and favored those predators with a larger body size and individual weight. After 1 year recovery, Collembola abundance recovered to the pre-treatment levels, while with Arthropod and Acari groups were still fluctuating.

Stronger warming effects on microbial abundances in colder regions

DOE PAGES

Chen, Ji; Luo, Yiqi; Xia, Jianyang; ...

2015-12-10

Soil microbes play critical roles in regulating terrestrial carbon (C) cycle and its feedback to climate change. However, it is still unclear how the soil microbial community and abundance respond to future climate change scenarios. In this meta-analysis, we synthesized the responses of microbial community and abundance to experimental warming from 64 published field studies. Our results showed that warming significantly increased soil microbial abundance by 7.6% on average. When grouped by vegetation or soil types, tundras and histosols had the strongest microbial responses to warming with increased microbial, fungal, and bacterial abundances by 15.0%, 9.5% and 37.0% in tundra,more » and 16.5%, 13.2% and 13.3% in histosols, respectively. We found significant negative relationships of the response ratios of microbial, fungal and bacterial abundances with the mean annual temperature, indicating that warming had stronger effects in colder than warmer regions. Moreover, the response ratios of microbial abundance to warming were positively correlated with those of soil respiration. Our results therefore indicate that the large quantities of C stored in colder regions are likely to be more vulnerable to climate warming than the soil C stored in other warmer regions.« less

Impact of Grassland Reseeding, Herbicide Spraying and Ploughing on Diversity and Abundance of Soil Arthropods

PubMed Central

Liu, Wei; Zhang, Junling; Norris, Stuart L.; Murray, Philip J.

2016-01-01

In order to determine the interactive effect of reseeding, herbicide spraying and ploughing on soil fauna communities, we conducted a grassland reseeding experiment combined with pre-reseed management to examine how with the whole reseeding process affects soil faunal composition. Sampling occasions and exact treatments were as follows: (1) before chemical herbicide spray; (2) after spray but before ploughing; (3) after ploughing but before reseeding; and (4) after 1 year of recovery. Our results demonstrate that, Acari and Collembola were the two soil fauna taxa with the highest abundance and accounted for around 96% of the relative total abundance among the various managements. Herbicide application tended to increase soil invertebrate abundance. Conversely, subsequent ploughing significantly reduced soil invertebrate abundance and had an obvious negative effect on soil primary and secondary decomposers, which were mainly due to the variations of Acari (especially Oribatida) and Coleoptera group abundance. Moreover, reseeding also reduced the individual number of the groups mentioned above, and favored those predators with a larger body size and individual weight. After 1 year recovery, Collembola abundance recovered to the pre-treatment levels, while with Arthropod and Acari groups were still fluctuating. PMID:27555863

Stronger warming effects on microbial abundances in colder regions

PubMed Central

Chen, Ji; Luo, Yiqi; Xia, Jianyang; Jiang, Lifen; Zhou, Xuhui; Lu, Meng; Liang, Junyi; Shi, Zheng; Shelton, Shelby; Cao, Junji

2015-01-01

Soil microbes play critical roles in regulating terrestrial carbon (C) cycle and its feedback to climate change. However, it is still unclear how the soil microbial community and abundance respond to future climate change scenarios. In this meta-analysis, we synthesized the responses of microbial community and abundance to experimental warming from 64 published field studies. Our results showed that warming significantly increased soil microbial abundance by 7.6% on average. When grouped by vegetation or soil types, tundras and histosols had the strongest microbial responses to warming with increased microbial, fungal, and bacterial abundances by 15.0%, 9.5% and 37.0% in tundra, and 16.5%, 13.2% and 13.3% in histosols, respectively. We found significant negative relationships of the response ratios of microbial, fungal and bacterial abundances with the mean annual temperature, indicating that warming had stronger effects in colder than warmer regions. Moreover, the response ratios of microbial abundance to warming were positively correlated with those of soil respiration. Our findings therefore indicate that the large quantities of C stored in colder regions are likely to be more vulnerable to climate warming than the soil C stored in other warmer regions. PMID:26658882

Estimating site occupancy and abundance using indirect detection indices

USGS Publications Warehouse

Stanley, T.R.; Royle, J. Andrew

2005-01-01

Knowledge of factors influencing animal distribution and abundance is essential in many areas of ecological research, management, and policy-making. Because common methods for modeling and estimating abundance (e.g., capture-recapture, distance sampling) are sometimes not practical for large areas or elusive species, indices are sometimes used as surrogate measures of abundance. We present an extension of the Royle and Nichols (2003) generalization of the MacKenzie et al. (2002) site-occupancy model that incorporates length of the sampling interval into the, model for detection probability. As a result, we obtain a modeling framework that shows how useful information can be extracted from a class of index methods we call indirect detection indices (IDIs). Examples of IDIs include scent station, tracking tube, snow track, tracking plate, and hair snare surveys. Our model is maximum likelihood, and it can be used to estimate site occupancy and model factors influencing patterns of occupancy and abundance in space. Under certain circumstances, it can also be used to estimate abundance. We evaluated model properties using Monte Carlo simulations and illustrate the method with tracking tube and scent station data. We believe this model will be a useful tool for determining factors that influence animal distribution and abundance.

SBS 0335-052E+W: deep VLT/FORS+UVES spectroscopy of the pair of the lowest-metallicity blue compact dwarf galaxies

NASA Astrophysics Data System (ADS)

Izotov, Y. I.; Guseva, N. G.; Fricke, K. J.; Papaderos, P.

2009-08-01

Context: We present deep archival VLT/FORS1+UVES spectroscopic observations of the system of two blue compact dwarf (BCD) galaxies SBS 0335-052E and SBS 0335-052W. Aims: Our aim is to derive element abundances in different H ii regions of this unique system of galaxies and to study spatial abundance variations. Methods: The electron temperature Te (O iii) in all H ii regions, except for one, is derived from the [O iii] λ4363/(λ4959+λ5007) flux ratio. We determine ionic abundances of helium, nitrogen, oxygen, neon, sulfur, chlorine, argon and iron. The empirical relations for ionization correction factors are used to derive total abundances of these elements. Results: The oxygen abundance in the brighter eastern galaxy varies in the range 7.11 to 7.32 in different H ii regions supporting previous findings and suggesting the presence of oxygen abundance variations on spatial scales of ~1-2 kpc. Good seeing during FORS observations allowed us to extract spectra of four H ii regions in SBS 0335-052W. The oxygen abundance in the brightest region No. 1 of SBS 0335-052W is 7.22 ± 0.07, consistent with previous determinations. Three other H ii regions are much more metal-poor with an unprecedently low oxygen abundance of 12 + log O/H = 7.01 ± 0.07 (region No. 2), 6.98 ± 0.06 (region No. 3), and 6.86 ± 0.14 (region No. 4). These are the lowest oxygen abundances ever derived in emission-line galaxies, supporting earlier conclusions that SBS 0335-052W is the lowest-metallicity emission-line galaxy known. Helium abundances derived for the brightest H ii regions of both galaxies are mutually consistent. We derive weighted mean He mass fractions of 0.2485 ± 0.0012 and 0.2514 ± 0.0012 for two different sets of He i emissivities. The ratios of neon and sulfur to oxygen abundance are similar to the respective ratios obtained for other emission-line galaxies. On the other hand, the chlorine-to-oxygen abundance ratio in SBS 0335-052E is lower, while the argon-to-oxygen abundance ratio is higher than those in other low-metallicity galaxies. The Fe/O abundance ratios in different regions of SBS 0335-052E are among the highest for emission-line galaxies implying that iron is almost entirely not depleted onto dust grains despite dust being detected in this galaxy in earlier ISO and Spitzer observations. The N/O abundance ratio in both galaxies is slightly higher than that derived for other BCDs with 12 + log O/H < 7.6. This implies that the N/O in extremely metal-deficient galaxies could increase with decreasing metallicity. Based on observations collected at the European Southern Observatory, Chile, ESO program 69.C-0203(A), 71.B-0055(A)), 70.B-0717(A) and 68.B-0310(A). Tables [see full textsee full text]-[see full textsee full text] are only available in electronic form at http://www.aanda.org

Robust Abundance Estimation in Animal Abundance Surveys with Imperfect Detection

EPA Science Inventory

Surveys of animal abundance are central to the conservation and management of living natural resources. However, detection uncertainty complicates the sampling process of many species. One sampling method employed to deal with this problem is depletion (or removal) surveys in whi...

Trace-element abundances in several new ureilites

NASA Technical Reports Server (NTRS)

Boynton, William V.; Hill, Dolores H.

1993-01-01

Four new ureilites are analyzed for trace-element abundances. Frontier Mountain (FRO) 90054 is an augite-rich ureilite and has high rare earth element (REE) abundances with a pattern expected of augite. FRO 90036 and Acfer 277 have REE patterns similar to the V-shape pattern of other ureilites. Nuevo Mercurio (b) has very high REE abundances, but they look like they are due to terrestrial alteration. The siderophile-element pattern of these ureilites are similar to those of known ureilites.

Temperature and Gravity Dependence of Trace Element Abundances in Hot DA White Dwarfs (94-EUVE-094)

NASA Technical Reports Server (NTRS)

Finley, David S.

1998-01-01

EUV spectroscopy has shown that DA white dwarfs hotter than about 45,000 K may contain trace heavy elements, while those hotter than about 50,000 K almost always have significant abundances of trace heavy elements. One of our continuing challenges is to identify and determine the abundances of these trace constituents, and then to relate the observed abundance patterns to the present conditions and previous evolutionary histories of the hot DA white dwarfs.

Interstellar Abundances Toward X Per, Revisited

NASA Technical Reports Server (NTRS)

Valencic, Lynne A.; Smith, Randall K.

2014-01-01

The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to measure elemental abundances in the local ISM. We examine absorption features of 0, Mg, and Si along this line of sight using spectra from the Chandra Observatory's LETG/ ACIS-S and XMM-Newton's RGS instruments. In general, we find that the abundances and their ratios are similar to those of young F and G stars and the most recent solar values. We compare our results with abundances required by dust grain models.

Interstellar Abundances Toward X Per, Revisited

NASA Technical Reports Server (NTRS)

Valencic, Lynne A.; Smith, Randall K.

2012-01-01

The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to measure elemental abundances in the local ISM. We examine absorption features of O, Mg, and Si along this line of sight using spectra from the Chandra Observatory's LETG/ACIS-S and XMM-Newton's RGS instruments. In general, we find that the abundances and their ratios are similar to those of young F and G stars and the most recent solar values. We compare our results with abundances required by dust grain models.

Potassium in the atmosphere of Mercury

NASA Technical Reports Server (NTRS)

Potter, A. E.; Morgan, T. H.

1986-01-01

Spectral data are reported from a search for potassium in the Mercury atmosphere. The data were collected with instrumentation at Kitt Peak (7699 A) and at McDonald Observatory (7698.98 and 7664.86 A). The equivalent mean widths of the potassium emission lines observed are tabulated, along with the estimated abundances, which are compared with sodium abundances as determined by resonance lines. The average column abundance of potassium is projected to be 1 billion atoms/sq cm, about 1 percent the column abundance of sodium.

Pendrin protein abundance in the kidney is regulated by nitric oxide and cAMP.

PubMed

Thumova, Monika; Pech, Vladimir; Froehlich, Otto; Agazatian, Diana; Wang, Xiaonan; Verlander, Jill W; Kim, Young Hee; Wall, Susan M

2012-09-15

Pendrin is a Cl(-)/HCO(3)(-) exchanger, expressed in the apical regions of some intercalated cell subtypes, and is critical in the pressor response to angiotensin II. Since angiotensin type 1 receptor inhibitors reduce renal pendrin protein abundance in mice in vivo through a mechanism that is dependent on nitric oxide (NO), we asked if NO modulates renal pendrin expression in vitro and explored the mechanism by which it occurs. Thus we quantified pendrin protein abundance by confocal fluorescent microscopy in cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs). After overnight culture, CCDs maintain their tubular structure and maintain a solute gradient when perfused in vitro. Pendrin protein abundance increased 67% in CNT and 53% in CCD when NO synthase was inhibited (N(G)-nitro-L-arginine methyl ester, 100 μM), while NO donor (DETA NONOate, 200 μM) application reduced pendrin protein by ∼33% in the CCD and CNT. When CNTs were cultured in the presence of the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 μM), NO donors did not alter pendrin abundance. Conversely, pendrin protein abundance rose when cAMP content was increased by the application of an adenylyl cyclase agonist (forskolin, 10 μM), a cAMP analog (8-bromo-cAMP, 1 mM), or a phosphodiesterase inhibitor (BAY60-7550, 50 μM). Since NO reduces cellular cAMP in the CNT, we asked if NO reduces pendrin abundance by reducing cAMP. With blockade of cGMP-stimulated phosphodiesterase II, NO did not alter pendrin protein abundance. We conclude that NO acts through cAMP to reduce pendrin total protein abundance by enhancing cAMP degradation.

Pendrin protein abundance in the kidney is regulated by nitric oxide and cAMP

PubMed Central

Thumova, Monika; Pech, Vladimir; Froehlich, Otto; Agazatian, Diana; Wang, Xiaonan; Verlander, Jill W.; Kim, Young Hee

2012-01-01

Pendrin is a Cl−/HCO3− exchanger, expressed in the apical regions of some intercalated cell subtypes, and is critical in the pressor response to angiotensin II. Since angiotensin type 1 receptor inhibitors reduce renal pendrin protein abundance in mice in vivo through a mechanism that is dependent on nitric oxide (NO), we asked if NO modulates renal pendrin expression in vitro and explored the mechanism by which it occurs. Thus we quantified pendrin protein abundance by confocal fluorescent microscopy in cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs). After overnight culture, CCDs maintain their tubular structure and maintain a solute gradient when perfused in vitro. Pendrin protein abundance increased 67% in CNT and 53% in CCD when NO synthase was inhibited (NG-nitro-l-arginine methyl ester, 100 μM), while NO donor (DETA NONOate, 200 μM) application reduced pendrin protein by ∼33% in the CCD and CNT. When CNTs were cultured in the presence of the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 μM), NO donors did not alter pendrin abundance. Conversely, pendrin protein abundance rose when cAMP content was increased by the application of an adenylyl cyclase agonist (forskolin, 10 μM), a cAMP analog (8-bromo-cAMP, 1 mM), or a phosphodiesterase inhibitor (BAY60-7550, 50 μM). Since NO reduces cellular cAMP in the CNT, we asked if NO reduces pendrin abundance by reducing cAMP. With blockade of cGMP-stimulated phosphodiesterase II, NO did not alter pendrin protein abundance. We conclude that NO acts through cAMP to reduce pendrin total protein abundance by enhancing cAMP degradation. PMID:22811483

Wetland characteristics linked to broad-scale patterns in Culiseta melanura abundance and eastern equine encephalitis virus infection.

PubMed

Skaff, Nicholas K; Armstrong, Philip M; Andreadis, Theodore G; Cheruvelil, Kendra S

2017-10-18

Eastern equine encephalitis virus (EEEV) is an expanding mosquito-borne threat to humans and domestic animal populations in the northeastern United States. Outbreaks of EEEV are challenging to predict due to spatial and temporal uncertainty in the abundance and viral infection of Cs. melanura, the principal enzootic vector. EEEV activity may be closely linked to wetlands because they provide essential habitat for mosquito vectors and avian reservoir hosts. However, wetlands are not homogeneous and can vary by vegetation, connectivity, size, and inundation patterns. Wetlands may also have different effects on EEEV transmission depending on the assessed spatial scale. We investigated associations between wetland characteristics and Cs. melanura abundance and infection with EEEV at multiple spatial scales in Connecticut, USA. Our findings indicate that wetland vegetative characteristics have strong associations with Cs. melanura abundance. Deciduous and evergreen forested wetlands were associated with higher Cs. melanura abundance, likely because these wetlands provide suitable subterranean habitat for Cs. melanura development. In contrast, Cs. melanura abundance was negatively associated with emergent and scrub/shrub wetlands, and wetland connectivity to streams. These relationships were generally strongest at broad spatial scales. Additionally, the relationships between wetland characteristics and EEEV infection in Cs. melanura were generally weak. However, Cs. melanura abundance was strongly associated with EEEV infection, suggesting that wetland-associated changes in abundance may be indirectly linked to EEEV infection in Cs. melanura. Finally, we found that wet hydrological conditions during the transmission season and during the fall/winter preceding the transmission season were associated with higher Cs. melanura abundance and EEEV infection, indicating that wet conditions are favorable for EEEV transmission. These results expand the broad-scale understanding of the effects of wetlands on EEEV transmission and help to reduce the spatial and temporal uncertainty associated with EEEV outbreaks.

Linking species abundance distributions in numerical abundance and biomass through simple assumptions about community structure.

PubMed

Henderson, Peter A; Magurran, Anne E

2010-05-22

Species abundance distributions (SADs) are widely used as a tool for summarizing ecological communities but may have different shapes, depending on the currency used to measure species importance. We develop a simple plotting method that links SADs in the alternative currencies of numerical abundance and biomass and is underpinned by testable predictions about how organisms occupy physical space. When log numerical abundance is plotted against log biomass, the species lie within an approximately triangular region. Simple energetic and sampling constraints explain the triangular form. The dispersion of species within this triangle is the key to understanding why SADs of numerical abundance and biomass can differ. Given regular or random species dispersion, we can predict the shape of the SAD for both currencies under a variety of sampling regimes. We argue that this dispersion pattern will lie between regular and random for the following reasons. First, regular dispersion patterns will result if communities are comprised groups of organisms that use different components of the physical space (e.g. open water, the sea bed surface or rock crevices in a marine fish assemblage), and if the abundance of species in each of these spatial guilds is linked to the way individuals of varying size use the habitat. Second, temporal variation in abundance and sampling error will tend to randomize this regular pattern. Data from two intensively studied marine ecosystems offer empirical support for these predictions. Our approach also has application in environmental monitoring and the recognition of anthropogenic disturbance, which may change the shape of the triangular region by, for example, the loss of large body size top predators that occur at low abundance.

Salinity Drives the Virioplankton Abundance but Not Production in Tropical Coastal Lagoons.

PubMed

Junger, Pedro C; Amado, André M; Paranhos, Rodolfo; Cabral, Anderson S; Jacques, Saulo M S; Farjalla, Vinicius F

2018-01-01

Viruses are the most abundant components of microbial food webs and play important ecological and biogeochemical roles in aquatic ecosystems. Virioplankton is regulated by several environmental factors, such as salinity, turbidity, and humic substances. However, most of the studies aimed to investigate virioplankton regulation were conducted in temperate systems combining a limited range of environmental variables. In this study, virus abundance and production were determined and their relation to bacterial and limnological variables was assessed in 20 neighboring shallow tropical coastal lagoons that present wide environmental gradients of turbidity (2.32-571 NTU), water color (1.82-92.49 m -1 ), dissolved organic carbon (0.71-16.7 mM), salinity (0.13-332.1‰), and chlorophyll-a (0.28 to 134.5 μg L -1 ). Virus abundance varied from 0.37 × 10 8 to 117 × 10 8 virus-like-particle (VLP) mL -1 , with the highest values observed in highly salty aquatic systems. Salinity and heterotrophic bacterial abundance were the main variables positively driving viral abundances in these lagoons. We suggest that, with increased salinity, there is a decrease in the protozoan control on bacterial populations and lower bacterial diversity (higher encounter rates with virus specific hosts), both factors positively affecting virus abundance. Virus production varied from 0.68 × 10 7 to 56.5 × 10 7 VLP mL -1 h -1 and was regulated by bacterial production and total phosphorus, but it was not directly affected by salinity. The uncoupling between virus abundance and virus production supports that the hypothesis that the lack of grazing pressure on viral and bacterial populations is an important mechanism causing virus abundance to escalate with increasing salt concentrations.

Temporal changes in soil bacterial and archaeal communities with different fertilizers in tea orchards.

PubMed

Wang, Hua; Yang, Shao-hui; Yang, Jing-ping; Lv, Ya-min; Zhao, Xing; Pang, Ji-liang

2014-11-01

It is important to understand the effects of temporal changes in microbial communities in the acidic soils of tea orchards with different fertilizers. A field experiment involving organic fertilizer (OF), chemical fertilizer (CF), and unfertilized control (CK) treatments was arranged to analyze the temporal changes in the bacterial and archaeal communities at bimonthly intervals based on the 16S ribosomal RNA (rRNA) gene using terminal restriction fragment length polymorphism (T-RFLP) profiling. The abundances of total bacteria, total archaea, and selected functional genes (bacterial and archaeal amoA, bacterial narG, nirK, nirS, and nosZ) were determined by quantitative polymerase chain reaction (qPCR). The results indicate that the structures of bacterial and archaeal communities varied significantly with time and fertilization based on changes in the relative abundance of dominant T-RFs. The abundancy of the detected genes changed with time. The total bacteria, total archaea, and archaeal amoA were less abundant in July. The bacterial amoA and denitrifying genes were less abundant in September, except the nirK gene. The OF treatment increased the abundance of the observed genes, while the CF treatment had little influence on them. The soil temperature significantly affected the bacterial and archaeal community structures. The soil moisture was significantly correlated with the abundance of denitrifying genes. Of the soil chemical properties, soil organic carbon was the most important factor and was significantly correlated with the abundance of the detected genes, except the nirK gene. Overall, this study demonstrated the effects of both temporal alteration and organic fertilizer on the structures of microbial communities and the abundance of genes involved in the nitrogen cycle.

Temporal changes in soil bacterial and archaeal communities with different fertilizers in tea orchards* #

PubMed Central

Wang, Hua; Yang, Shao-hui; Yang, Jing-ping; Lv, Ya-min; Zhao, Xing; Pang, Ji-liang

2014-01-01

It is important to understand the effects of temporal changes in microbial communities in the acidic soils of tea orchards with different fertilizers. A field experiment involving organic fertilizer (OF), chemical fertilizer (CF), and unfertilized control (CK) treatments was arranged to analyze the temporal changes in the bacterial and archaeal communities at bimonthly intervals based on the 16S ribosomal RNA (rRNA) gene using terminal restriction fragment length polymorphism (T-RFLP) profiling. The abundances of total bacteria, total archaea, and selected functional genes (bacterial and archaeal amoA, bacterial narG, nirK, nirS, and nosZ) were determined by quantitative polymerase chain reaction (qPCR). The results indicate that the structures of bacterial and archaeal communities varied significantly with time and fertilization based on changes in the relative abundance of dominant T-RFs. The abundancy of the detected genes changed with time. The total bacteria, total archaea, and archaeal amoA were less abundant in July. The bacterial amoA and denitrifying genes were less abundant in September, except the nirK gene. The OF treatment increased the abundance of the observed genes, while the CF treatment had little influence on them. The soil temperature significantly affected the bacterial and archaeal community structures. The soil moisture was significantly correlated with the abundance of denitrifying genes. Of the soil chemical properties, soil organic carbon was the most important factor and was significantly correlated with the abundance of the detected genes, except the nirK gene. Overall, this study demonstrated the effects of both temporal alteration and organic fertilizer on the structures of microbial communities and the abundance of genes involved in the nitrogen cycle. PMID:25367788

HIGH PRECISION ABUNDANCES OF THE OLD SOLAR TWIN HIP 102152: INSIGHTS ON Li DEPLETION FROM THE OLDEST SUN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monroe, TalaWanda R.; Melendez, Jorge; Tucci Maia, Marcelo

2013-09-10

We present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex ({approx}<1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 {+-} 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratiosmore » examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log {epsilon} (Li) = 0.48 {+-} 0.07, 1.62 {+-} 0.02, and 1.07 {+-} 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.« less

Bee Abundance and Nutritional Status in Relation to Grassland Management Practices in an Agricultural Landscape.

PubMed

Smith, Griffin W; Debinski, Diane M; Scavo, Nicole A; Lange, Corey J; Delaney, John T; Moranz, Raymond A; Miller, James R; Engle, David M; Toth, Amy L

2016-04-01

Grasslands provide important resources for pollinators in agricultural landscapes. Managing grasslands with fire and grazing has the potential to benefit plant and pollinator communities, though there is uncertainty about the ideal approach. We examined the relationships among burning and grazing regimes, plant communities, and Bombus species and Apis mellifera L. abundance and nutritional indicators at the Grand River Grasslands in southern Iowa and northern Missouri. Treatment regimes included burn-only, grazed-and-burned, and patch-burn graze (pastures subdivided into three temporally distinct fire patches with free access by cattle). The premise of the experimental design was that patch-burn grazing would increase habitat heterogeneity, thereby providing more diverse and abundant floral resources for pollinators. We predicted that both bee abundance and individual bee nutritional indicators (bee size and lipid content) would be positively correlated with floral resource abundance. There were no significant differences among treatments with respect to bee abundance. However, some of the specific characteristics of the plant community showed significant relationships with bee response variables. Pastures with greater abundance of floral resources had greater bee abundance but lower bee nutritional indicators. Bee nutritional variables were positively correlated with vegetation height, but, in some cases, negatively correlated with stocking rate. These results suggest grassland site characteristics such as floral resource abundance and stocking rate are of potential importance to bee pollinators and suggest avenues for further research to untangle the complex interactions between grassland management, plant responses, and bee health. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bringing abundance into environmental politics: Constructing a Zionist network of water abundance, immigration, and colonization.

PubMed

Alatout, Samer

2009-06-01

For more than five decades, resource scarcity has been the lead story in debates over environmental politics. More importantly, and whenever environmental politics implies conflict, resource scarcity is constructed as the culprit. Abundance of resources, if at all visited in the literature, holds less importance. Resource abundance is seen, at best, as the other side of scarcity--maybe the successful conclusion of multiple interventions that may turn scarcity into abundance. This paper reinstates abundance as a politico-environmental category in its own right. Rather than relegating abundance to a second-order environmental actor that matters only on occasion, this paper foregrounds it as a crucial element in modern environmental politics. On the substantive level, and using insights from science and technology studies, especially a slightly modified actor-network framework, I describe the emergence and consolidation of a Zionist network of abundance, immigration, and colonization in Palestine between 1918 and 1948. The essential argument here is that water abundance was constructed as fact, and became a political rallying point around which a techno-political network emerged that included a great number of elements. To name just a few, the following were enrolled in the service of such a network: geologists, geophysicists, Zionist settlement experts, Zionist organizations, political and technical categories of all sorts, Palestinians as the negated others, Palestinian revolts in search of political rights, the British Mandate authorities, the hydrological system of Palestine, and the absorptive capacity of Palestine, among others. The point was to successfully articulate these disparate elements into a network that seeks opening Palestine for Jewish immigration, redefining Palestinian geography and history through Judeo-Christian Biblical narratives, and, in the process, de-legitimizing political Palestinian presence in historic Palestine.

Multiple Ant Species Tending Lac Insect Kerria yunnanensis (Hemiptera: Kerriidae) Provide Asymmetric Protection against Parasitoids

PubMed Central

Li, Qiao; Hoffmann, Benjamin D.; Zhang, Wei

2014-01-01

This study investigated the effects of ant attendance on the parasitoid community and parasitism of lac insect Kerria yunnanensis aggregations in Yunnan province, China. We manipulated ant attendance to establish three treatments: (1) ant exclusion; (2) low ant attendance by several ant species; and (3) high ant attendance by Crematogaster macaoensis. Five parasitoid species were collected, with two species contributing 82.7 and 13.2% of total abundance respectively. Total parasitoid abundance was lowest in the February sample when K. yunnanensis was in its younger life stage, being significantly lower in the ant exclusion treatment. In April, all three treatments had significantly different parasitoid abundances, being highest in the ant exclusion treatment and the lowest in the high ant attendance treatment. When ants were present, there were strong negative relationships between total parasitoid abundance and ant abundance, with the relationships being dependent upon the ant species composition and abundance. The patterns of total parasitoid abundance were driven by the two most abundant parasitoid species. Parasitoid species richness did not differ among treatments or between sample times, however, multivariate analysis confirmed that overall parasitoid community structure differed significantly among treatments and between sample times, with the high ant attendance treatment differing most from the other two treatments. Interestingly the absence of ants did not result in increased parasitism from four of the five parasitoids. Ants in lac insect farming systems have a clear role for agricultural pest management. A full understanding of the asymmetric abilities of ants to influence parasitoid communities, and affect parasitism of hosts will require further experimental manipulation to assess the relative roles of 1) the abundance of each individual ant species on parasitoid access to hosts, 2) competition among parasitoids, and 3) the interaction between the first two factors. PMID:24887398

THE EFFECTS OF INITIAL ABUNDANCES ON NITROGEN IN PROTOPLANETARY DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarz, Kamber R.; Bergin, Edwin A.

2014-12-20

The dominant form of nitrogen provided to most solar system bodies is currently unknown, though available measurements show that the detected nitrogen in solar system rocks and ices is depleted with respect to solar abundances and the interstellar medium. We use a detailed chemical/physical model of the chemical evolution of a protoplanetary disk to explore the evolution and abundance of nitrogen-bearing molecules. Based on this model, we analyze how initial chemical abundances provided as either gas or ice during the early stages of disk formation influence which species become the dominant nitrogen bearers at later stages. We find that amore » disk with the majority of its initial nitrogen in either atomic or molecular nitrogen is later dominated by atomic and molecular nitrogen as well as NH{sub 3} and HCN ices, where the dominant species varies with disk radius. When nitrogen is initially in gaseous ammonia, it later becomes trapped in ammonia ice except in the outer disk where atomic nitrogen dominates. For a disk with the initial nitrogen in the form of ammonia ice, the nitrogen remains trapped in the ice as NH{sub 3} at later stages. The model in which most of the initial nitrogen is placed in atomic N best matches the ammonia abundances observed in comets. Furthermore, the initial state of nitrogen influences the abundance of N{sub 2}H{sup +}, which has been detected in protoplanetary disks. Strong N{sub 2}H{sup +} emission is found to be indicative of an N{sub 2} abundance greater than n{sub N{sub 2}}/n{sub H{sub 2}}>10{sup −6} in addition to tracing the CO snow line. Our models also indicate that NO is potentially detectable, with lower N gas abundances leading to higher NO abundances.« less

Project VeSElkA: a search for the vertical stratification of element abundances in HD 157087

NASA Astrophysics Data System (ADS)

Khalack, V.

2018-06-01

The new spectropolarimetric spectra of HD 157087 obtained recently with ESPaDOnS (Echelle SpectroPolarimetric Device for Observations of Stars) at the Canada-France-Hawaii Telescope are analysed to verify the nature of this object. The fundamental stellar parameters Teff = 8882 K, log g = 3.57 were obtained for HD 157087 from the analysis of nine Balmer line profiles in two available spectra. A comparison of the results of our abundance analysis with previously published data shows a variability of the average abundance with time for some chemical species, while the abundances of other elements remain almost constant. The abundance analysis also reveals evidence of a significant abundance increase towards the deeper atmospheric layers for C, S, Ca, Sc, V, Cr, Mn, Co, Ni and Zr. Together with the discovered enhanced abundance of Ca and Sc, this finding contradicts the classification of HD 157087 as a marginal Am star. An analysis of the available measurements of radial velocity revealed long- and short-period variations. The long-period variation supports the idea that HD 157087 is an astrometric binary system with a period longer than 6 yr. The presence of the short-period variation of Vr, as well as the detection of the temporal variation of the average abundance, suggests that HD 157087 may be a triple system, in which a short-period binary rotates around a third star. In this case, the short-period binary may consist of slowly rotating Am and A (or Ap with a weak magnetic field) stars that have similar effective temperatures and surface gravities, but different abundance peculiarities.

Origin of central abundances in the hot intra-cluster medium. I. Individual and average abundance ratios from XMM-Newton EPIC

NASA Astrophysics Data System (ADS)

Mernier, F.; de Plaa, J.; Pinto, C.; Kaastra, J. S.; Kosec, P.; Zhang, Y.-Y.; Mao, J.; Werner, N.

2016-08-01

The hot intra-cluster medium (ICM) is rich in metals, which are synthesised by supernovae (SNe) explosions and accumulate over time into the deep gravitational potential well of clusters of galaxies. Since most of the elements visible in X-rays are formed by type Ia (SNIa) and/or core-collapse (SNcc) supernovae, measuring their abundances gives us direct information on the nucleosynthesis products of billions of SNe since the epoch of the star formation peak (z ~ 2-3). In this study, we use the EPIC and RGS instruments on board XMM-Newton to measure the abundances of nine elements (O, Ne, Mg, Si, S, Ar, Ca, Fe, and Ni) from a sample of 44 nearby cool-core galaxy clusters, groups, and elliptical galaxies. We find that the Fe abundance shows a large scatter (~20-40%) over the sample, within 0.2r500 and especially 0.05r500. Unlike the absolute Fe abundance, the abundance ratios (X/Fe) are uniform over the considered temperature range (~0.6-8 keV) and with a limited scatter. In addition to an unprecedented treatment of systematic uncertainties, we provide the most accurate abundance ratios measured so far in the ICM, including Cr/Fe and Mn/Fe which we firmly detected (>4σ with MOS and pn independently). We find that Cr/Fe, Mn/Fe, and Ni/Fe differ significantly from the proto-solar values. However, the large uncertainties in the proto-solar abundances prevent us from making a robust comparison between the local and the intra-cluster chemical enrichments. We also note that, interestingly, and despite the large net exposure time (~4.5 Ms) of our dataset, no line emission feature is seen around ~3.5 keV.

Bi-Abundance Ionisation Structure of the Wolf-Rayet Planetary Nebula PB 8

NASA Astrophysics Data System (ADS)

Danehkar, A.

2018-01-01

The planetary nebula PB 8 around a [WN/WC]-hybrid central star is one of planetary nebulae with moderate abundance discrepancy factors (ADFs 2-3), which could be an indication of a tiny fraction of metal-rich inclusions embedded in the nebula (bi-abundance). In this work, we have constructed photoionisation models to reproduce the optical and infrared observations of the planetary nebula PB 8 using a non-LTE stellar model atmosphere ionising source. A chemically homogeneous model initially used cannot predict the optical recombination lines. However, a bi-abundance model provides a better fit to most of the observed optical recombination lines from N and O ions. The metal-rich inclusions in the bi-abundance model occupy 5.6% of the total volume of the nebula, and are roughly 1.7 times cooler and denser than the mean values of the surrounding nebula. The N/H and O/H abundance ratios in the metal-rich inclusions are 1.0 and 1.7 dex larger than the diffuse warm nebula, respectively. To reproduce the Spitzer spectral energy distribution of PB 8, dust grains with a dust-to-gas ratio of 0.01 (by mass) were also included. It is found that the presence of metal-rich inclusions can explain the heavy element optical recombination lines, while a dual-dust chemistry with different grain species and discrete grain sizes likely produces the infrared continuum of this planetary nebula. This study demonstrates that the bi-abundance hypothesis, which was examined in a few planetary nebulae with large abundance discrepancies (ADFs > 10), could also be applied to those typical planetary nebulae with moderate abundance discrepancies.

Ca. Nitrososphaera and Bradyrhizobium are inversely correlated and related to agricultural practices in long-term field experiments

PubMed Central

Zhalnina, Kateryna; de Quadros, Patricia D.; Gano, Kelsey A.; Davis-Richardson, Austin; Fagen, Jennie R.; Brown, Christopher T.; Giongo, Adriana; Drew, Jennifer C.; Sayavedra-Soto, Luis A.; Arp, Dan J.; Camargo, Flavio A. O.; Daroub, Samira H.; Clark, Ian M.; McGrath, Steve P.; Hirsch, Penny R.; Triplett, Eric W.

2013-01-01

Agricultural land management, such as fertilization, liming, and tillage affects soil properties, including pH, organic matter content, nitrification rates, and the microbial community. Three different study sites were used to identify microorganisms that correlate with agricultural land use and to determine which factors regulate the relative abundance of the microbial signatures of the agricultural land-use. The three sites included in this study are the Broadbalk Experiment at Rothamsted Research, UK, the Everglades Agricultural Area, Florida, USA, and the Kellogg Biological Station, Michigan, USA. The effects of agricultural management on the abundance and diversity of bacteria and archaea were determined using high throughput, barcoded 16S rRNA sequencing. In addition, the relative abundance of these organisms was correlated with soil features. Two groups of microorganisms involved in nitrogen cycle were highly correlated with land use at all three sites. The ammonia oxidizing-archaea, dominated by Ca. Nitrososphaera, were positively correlated with agriculture while a ubiquitous group of soil bacteria closely related to the diazotrophic symbiont, Bradyrhizobium, was negatively correlated with agricultural management. Analysis of successional plots showed that the abundance of ammonia oxidizing-archaea declined and the abundance of bradyrhizobia increased with time away from agriculture. This observation suggests that the effect of agriculture on the relative abundance of these genera is reversible. Soil pH and NH3 concentrations were positively correlated with archaeal abundance but negatively correlated with the abundance of Bradyrhizobium. The high correlations of Ca. Nitrososphaera and Bradyrhizobium abundances with agricultural management at three long-term experiments with different edaphoclimatic conditions allowed us to suggest these two genera as signature microorganisms for agricultural land use. PMID:23641242

More than mere numbers: the impact of lethal control on the social stability of a top-order predator.

PubMed

Wallach, Arian D; Ritchie, Euan G; Read, John; O'Neill, Adam J

2009-09-02

Population control of socially complex species may have profound ecological implications that remain largely invisible if only their abundance is considered. Here we discuss the effects of control on a socially complex top-order predator, the dingo (Canis lupus dingo). Since European occupation of Australia, dingoes have been controlled over much of the continent. Our aim was to investigate the effects of control on their abundance and social stability. We hypothesized that dingo abundance and social stability are not linearly related, and proposed a theoretical model in which dingo populations may fluctuate between three main states: (A) below carrying capacity and socially fractured, (B) above carrying capacity and socially fractured, or (C) at carrying capacity and socially stable. We predicted that lethal control would drive dingoes into the unstable states A or B, and that relaxation of control would allow recovery towards C. We tested our predictions by surveying relative abundance (track density) and indicators of social stability (scent-marking and howling) at seven sites in the arid zone subject to differing degrees of control. We also monitored changes in dingo abundance and social stability following relaxation and intensification of control. Sites where dingoes had been controlled within the previous two years were characterized by low scent-marking activity, but abundance was similar at sites with and without control. Signs of social stability steadily increased the longer an area was allowed to recover from control, but change in abundance did not follow a consistent path. Comparison of abundance and stability among all sites and years demonstrated that control severely fractures social groups, but that the effect of control on abundance was neither consistent nor predictable. Management decisions involving large social predators must therefore consider social stability to ensure their conservation and ecological functioning.

Environmental DNA (eDNA) detects the invasive rusty crayfish Orconectes rusticus at low abundances.

PubMed

Dougherty, Matthew M; Larson, Eric R; Renshaw, Mark A; Gantz, Crysta A; Egan, Scott P; Erickson, Daniel M; Lodge, David M

2016-06-01

Early detection is invaluable for the cost-effective control and eradication of invasive species, yet many traditional sampling techniques are ineffective at the low population abundances found at the onset of the invasion process. Environmental DNA (eDNA) is a promising and sensitive tool for early detection of some invasive species, but its efficacy has not yet been evaluated for many taxonomic groups and habitat types.We evaluated the ability of eDNA to detect the invasive rusty crayfish Orconectes rusticus and to reflect patterns of its relative abundance, in upper Midwest, USA, inland lakes. We paired conventional baited trapping as a measure of crayfish relative abundance with water samples for eDNA, which were analysed in the laboratory with a qPCR assay. We modelled detection probability for O. rusticus eDNA using relative abundance and site characteristics as covariates and also tested the relationship between eDNA copy number and O. rusticus relative abundance.We detected O. rusticus eDNA in all lakes where this species was collected by trapping, down to low relative abundances, as well as in two lakes where trap catch was zero. Detection probability of O. rusticus eDNA was well predicted by relative abundance of this species and lake water clarity. However, there was poor correspondence between eDNA copy number and O. rusticus relative abundance estimated by trap catches. Synthesis and applications . Our study demonstrates a field and laboratory protocol for eDNA monitoring of crayfish invasions, with results of statistical models that provide guidance of sampling effort and detection probabilities for researchers in other regions and systems. We propose eDNA be included as a tool in surveillance for invasive or imperilled crayfishes and other benthic arthropods.

Non-local Thermodynamic Equilibrium Stellar Spectroscopy with 1D and <3D> Models. I. Methods and Application to Magnesium Abundances in Standard Stars

NASA Astrophysics Data System (ADS)

Bergemann, Maria; Collet, Remo; Amarsi, Anish M.; Kovalev, Mikhail; Ruchti, Greg; Magic, Zazralt

2017-09-01

We determine Mg abundances in six Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally and spatially averaged three-dimensional (<3D>) model atmospheres. The stars cover a range of Teff from 4700 to 6500 K, log g from 1.6 to 4.4 dex, and [Fe/H] from -3.0 dex to solar. Spectrum synthesis calculations are performed in local thermodynamic equilibrium (LTE) and in non-LTE (NLTE) using the oscillator strengths recently published by Pehlivan Rhodin et al. We find that: (a) Mg abundances determined from the infrared spectra are as accurate as the optical diagnostics, (b) the NLTE effects on Mg I line strengths and abundances in this sample of stars are minor (although for a few Mg I lines the NLTE effects on abundance exceed 0.6 dex in <3D> and 0.1 dex in 1D, (c) the solar Mg abundance is 7.56+/- 0.05 dex (total error), in excellent agreement with the Mg abundance measured in CI chondritic meteorites, (d) the 1D NLTE and <3D> NLTE approaches can be used with confidence to analyze optical Mg I lines in spectra of dwarfs and sub-giants, but for red giants the Mg I 5711 Å line should be preferred, (e) low-excitation Mg I lines are sensitive to the atmospheric structure; for these lines, LTE calculations with <3D> models lead to significant systematic abundance errors. The methods developed in this work will be used to study Mg abundances of a large sample of stars in the next paper in the series.

Linking species abundance distributions in numerical abundance and biomass through simple assumptions about community structure

PubMed Central

Henderson, Peter A.; Magurran, Anne E.

2010-01-01

Species abundance distributions (SADs) are widely used as a tool for summarizing ecological communities but may have different shapes, depending on the currency used to measure species importance. We develop a simple plotting method that links SADs in the alternative currencies of numerical abundance and biomass and is underpinned by testable predictions about how organisms occupy physical space. When log numerical abundance is plotted against log biomass, the species lie within an approximately triangular region. Simple energetic and sampling constraints explain the triangular form. The dispersion of species within this triangle is the key to understanding why SADs of numerical abundance and biomass can differ. Given regular or random species dispersion, we can predict the shape of the SAD for both currencies under a variety of sampling regimes. We argue that this dispersion pattern will lie between regular and random for the following reasons. First, regular dispersion patterns will result if communities are comprised groups of organisms that use different components of the physical space (e.g. open water, the sea bed surface or rock crevices in a marine fish assemblage), and if the abundance of species in each of these spatial guilds is linked to the way individuals of varying size use the habitat. Second, temporal variation in abundance and sampling error will tend to randomize this regular pattern. Data from two intensively studied marine ecosystems offer empirical support for these predictions. Our approach also has application in environmental monitoring and the recognition of anthropogenic disturbance, which may change the shape of the triangular region by, for example, the loss of large body size top predators that occur at low abundance. PMID:20071388

Stochastic species abundance models involving special copulas

NASA Astrophysics Data System (ADS)

Huillet, Thierry E.

2018-01-01

Copulas offer a very general tool to describe the dependence structure of random variables supported by the hypercube. Inspired by problems of species abundances in Biology, we study three distinct toy models where copulas play a key role. In a first one, a Marshall-Olkin copula arises in a species extinction model with catastrophe. In a second one, a quasi-copula problem arises in a flagged species abundance model. In a third model, we study completely random species abundance models in the hypercube as those, not of product type, with uniform margins and singular. These can be understood from a singular copula supported by an inflated simplex. An exchangeable singular Dirichlet copula is also introduced, together with its induced completely random species abundance vector.

Estimating abundance

USGS Publications Warehouse

Sutherland, Chris; Royle, Andy

2016-01-01

This chapter provides a non-technical overview of ‘closed population capture–recapture’ models, a class of well-established models that are widely applied in ecology, such as removal sampling, covariate models, and distance sampling. These methods are regularly adopted for studies of reptiles, in order to estimate abundance from counts of marked individuals while accounting for imperfect detection. Thus, the chapter describes some classic closed population models for estimating abundance, with considerations for some recent extensions that provide a spatial context for the estimation of abundance, and therefore density. Finally, the chapter suggests some software for use in data analysis, such as the Windows-based program MARK, and provides an example of estimating abundance and density of reptiles using an artificial cover object survey of Slow Worms (Anguis fragilis).

Estimating abundance: Chapter 27

USGS Publications Warehouse

Royle, J. Andrew

2016-01-01

This chapter provides a non-technical overview of ‘closed population capture–recapture’ models, a class of well-established models that are widely applied in ecology, such as removal sampling, covariate models, and distance sampling. These methods are regularly adopted for studies of reptiles, in order to estimate abundance from counts of marked individuals while accounting for imperfect detection. Thus, the chapter describes some classic closed population models for estimating abundance, with considerations for some recent extensions that provide a spatial context for the estimation of abundance, and therefore density. Finally, the chapter suggests some software for use in data analysis, such as the Windows-based program MARK, and provides an example of estimating abundance and density of reptiles using an artificial cover object survey of Slow Worms (Anguis fragilis).

Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

NASA Technical Reports Server (NTRS)

Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

1994-01-01

The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

Modelling bloom formation of the toxic dinoflagellates Dinophysis acuminata and Dinophysis caudata in a highly modified estuary, south eastern Australia

NASA Astrophysics Data System (ADS)

Ajani, Penelope; Larsson, Michaela E.; Rubio, Ana; Bush, Stephen; Brett, Steve; Farrell, Hazel

2016-12-01

Dinoflagellates belonging to the toxigenic genus Dinophysis are increasing in abundance in the Hawkesbury River, south-eastern Australia. This study investigates a twelve year time series of abundance and physico-chemical data to model these blooms. Four species were reported over the sampling campaign - Dinophysis acuminata, Dinophysis caudata, Dinophysis fortii and Dinophysis tripos-with D. acuminata and D. caudata being most abundant. Highest abundance of D. acuminata occurred in the austral spring (max. abundance 4500 cells l-1), whilst highest D. caudata occurred in the summer to autumn (max. 12,000 cells l-1). Generalised additive models revealed abundance of D. acuminata was significantly linked to season, thermal stratification and nutrients, whilst D. caudata was associated with nutrients, salinity and dissolved oxygen. The models' predictive capability was up to 60% for D. acuminata and 53% for D. caudata. Altering sampling strategies during blooms accompanied with in situ high resolution monitoring will further improve Dinophysis bloom prediction capability.

Exceptionally high abundances of microplastics in the oligotrophic Israeli Mediterranean coastal waters.

PubMed

van der Hal, Noam; Ariel, Asaf; Angel, Dror L

2017-03-15

Seasonal sea surface microplastic distribution was recorded at 17 sites along the Israeli Mediterranean coast. Microplastics (0.3-5mm) were found in all samples, with a mean abundance of 7.68±2.38particles/m 3 or 1,518,340particles/km 2 . Some areas had higher abundances of microplastics than others, although differences were neither consistent nor statistically significant. In some cases microplastic particles were found floating in large patches. One of these patches contained an extraordinary number of plastic particles; 324particles/m 3 or 64,812,600particles/km 2 . Microplastic abundances in Israeli coastal waters are disturbingly high; mean values were 1-2 orders of magnitude higher than abundances reported in other parts of the world. Light-colored (white or transparent) fragments were by far more abundant than all other microplastic colors and types. The results of this study underline the need for action to reduce the flux of plastics to the marine environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Abundance and composition of near surface microplastics and plastic debris in the Stockholm Archipelago, Baltic Sea.

PubMed

Gewert, Berit; Ogonowski, Martin; Barth, Andreas; MacLeod, Matthew

2017-07-15

We collected plastic debris in the Stockholm Archipelago using a manta trawl, and additionally along a transect in the Baltic Sea from the island of Gotland to Stockholm in a citizen science study. The samples were concentrated by filtration and organic material was digested using hydrogen peroxide. Suspected plastic material was isolated by visual sorting and 59 of these were selected to be characterized with Fourier transform infrared spectroscopy. Polypropylene and polyethylene were the most abundant plastics identified among the samples (53% and 24% respectively). We found nearly ten times higher abundance of plastics near central Stockholm than in offshore areas (4.2×10 5 plastics km -2 compared to 4.7×10 4 plastics km -2 ). The abundance of plastic debris near Stockholm was similar to urban areas in California, USA, and the overall abundance in the Stockholm Archipelago was similar to plastic abundance reported in the northwestern Mediterranean Sea. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Convergence and divergence in a long-term old-field succession: the importance of spatial scale and species abundance.

PubMed

Li, Shao-Peng; Cadotte, Marc W; Meiners, Scott J; Pu, Zhichao; Fukami, Tadashi; Jiang, Lin

2016-09-01

Whether plant communities in a given region converge towards a particular stable state during succession has long been debated, but rarely tested at a sufficiently long time scale. By analysing a 50-year continuous study of post-agricultural secondary succession in New Jersey, USA, we show that the extent of community convergence varies with the spatial scale and species abundance classes. At the larger field scale, abundance-based dissimilarities among communities decreased over time, indicating convergence of dominant species, whereas incidence-based dissimilarities showed little temporal tend, indicating no sign of convergence. In contrast, plots within each field diverged in both species composition and abundance. Abundance-based successional rates decreased over time, whereas rare species and herbaceous plants showed little change in temporal turnover rates. Initial abandonment conditions only influenced community structure early in succession. Overall, our findings provide strong evidence for scale and abundance dependence of stochastic and deterministic processes over old-field succession. © 2016 John Wiley & Sons Ltd/CNRS.

HOW MANY NUCLEOSYNTHESIS PROCESSES EXIST AT LOW METALLICITY?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, C. J.; Montes, F.; Arcones, A., E-mail: cjhansen@lsw.uni-heidelberg.de, E-mail: cjhansen@dark-cosmology.dk, E-mail: montes@nscl.msu.edu, E-mail: almudena.arcones@physik.tu-darmstadt.de

Abundances of low-metallicity stars offer a unique opportunity to understand the contribution and conditions of the different processes that synthesize heavy elements. Many old, metal-poor stars show a robust abundance pattern for elements heavier than Ba, and a less robust pattern between Sr and Ag. Here we probe if two nucleosynthesis processes are sufficient to explain the stellar abundances at low metallicity, and we carry out a site independent approach to separate the contribution from these two processes or components to the total observationally derived abundances. Our approach provides a method to determine the contribution of each process to themore » production of elements such as Sr, Zr, Ba, and Eu. We explore the observed star-to-star abundance scatter as a function of metallicity that each process leads to. Moreover, we use the deduced abundance pattern of one of the nucleosynthesis components to constrain the astrophysical conditions of neutrino-driven winds from core-collapse supernovae.« less

Interstellar Dust Models Consistent with Extinction, Emission, and Abundance Constraints

NASA Technical Reports Server (NTRS)

Zubko, Viktor; Dwek, Eli; Arendt, Richard G.

2004-01-01

We present new interstellar dust models which have been derived by simultaneously fitting the far ultraviolet to near infrared extinction, the diffuse infrared emission, and, unlike previous models, the elemental abundances in dust for the diffuse interstellar medium. We found that dust models consisting of a mixture of spherical graphite and silicate grains, polycyclic aromatic hydrocarbon (PAH) molecules, in addition to porous composite particles containing silicate, organic refractory, and water ice, provide an improved .t to the UV-to-infrared extinction and infrared emission measurements, while consuming the amounts of elements well within the uncertainties of adopted interstellar abundances, including B star abundances. These models are a signi.cant improvement over the recent Li & Draine (2001, ApJ, 554, 778) model which requires an excessive amount of silicon to be locked up in dust: 48 ppm (atoms per million of H atoms), considerably more than the solar abundance of 34 ppm or the B star abundance of 19 ppm.

Factors affecting the abundance of selected fishes near oil and gas platforms in the northern Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stanley, D.R.; Wilson, C.A.

1991-01-01

A logbook program was initiated to determine the relative abundance of selected fish species around oil and gas platforms off the Louisiana coast. Logbooks were maintained by 55 anglers and 10 charterboat operators from March 1987 to March 1988. A total of 36,839 fish were caught representing over 46 different species. Principal component analysis (PCA) grouped the seventeen most abundant species into reef fish, pelagic fish, bluefish-red drum, Atlantic croaker-silver/sand seatrout, and cobia-shark-blue runner associations. Multiple regression analyses were used to compare PCA groupings to physical platform, temporal, geological, and angler characteristic variables and their interactions. Reef fish, Atlantic croaker,more » and silver/sand seatrout abundances were highest near large, structurally complex platforms in relatively deep water. High spotted seatrout abundances were correlated with small, unmanned oil and gas platforms in shallow water. Pelagic fish, bluefish, red drum, cobia, and shark abundances were not related to the physical parameters of the platforms.« less

Aquatic Invertebrate Assemblages in Shallow Prairie Lakes: Fish and Environmental Influences

USGS Publications Warehouse

Paukert, C.P.; Willis, D.W.

2003-01-01

We sampled zooplankton and benthic macroinvertebrate assemblages in 30 shallow natural lakes to determine the effects of the environment (i.e., habitat and fish abundance) on invertebrates. Zooplankters were identified to genus, and up to 120 individuals per genus were measured. Macroinvertebrates were identified to order, class, or family. Fish communities were also sampled. Relative abundances of zooplankton and macroinvertebrates were low at increased chlorophyll a concentrations, although mean zooplankton length increased with total phosphorus, possibly because of an increased proportion of microzooplankton (rotifers and copepod nauplii) at higher phosphorus levels. Canonical correspondence analysis revealed that zooplankton and macroinvertebrate abundance was influenced by submersed vegetation coverage, whereas zooplankton abundance and size structure were also related to productivity (i.e., chlorophyll a and total phosphorus). However, relative abundance of fish species or fish feeding guilds was not strongly correlated with zooplankton or macroinvertebrate abundance or zooplankton size structure. Physical habitat (e.g., vegetation coverage) may exert substantial influences on invertebrate assemblages in these lakes, possibly providing a refuge from fish predation.

[Hummingbird abundance and flowers use in a template forest from Southeast Mexico].

PubMed

Partida Lara, Ruth; Enríquez, Paula L; Rangel-Salazar, José Luis; Lara, Carlos; Martínez Ico, Miguel

2012-12-01

Hummingbird abundance varies with plant bloom phenology used for feeding. However, the information on hummingbird-flower interaction is limited for tropical mountain environments. We evaluated hummingbird abundance using mist nest and estimated monthly flowering phenology visited by hummingbirds in three different habitats (oak forest, cloud forest and bush) from January to August 2010 in Huitepec Ecological Reserve. We recorded four hummingbird species (Hylocharis leucotis, Lampornis amethystinus, Lamprolaima rhami and Eugenes fulgens), and their abundance varied among habitats (H3.8=14.8, p=0.001). Seven plant species were visited for hummingbirds and showed the highest number of flower species during dry season. Bush had the highest blossom. Fuchsia paniculata had the highest blossom period but only was visited by H. leucotis. Passiflora membranacea was the only species visited for all hummingbird species. The only positive association was E. fulgens abundance with P.a membranacea bloom (r(S)=0.93, p=0.02). Hummingbird abundance fluctuations in this study are determined for interactions with floral resources and their habitat distribution.

The Mean Life Squared Relationship for Abundances of Extinct Radioactivities

NASA Technical Reports Server (NTRS)

Lodders, K.; Cameron, A. G. W.

2004-01-01

We discovered that the abundances of now extinct radioactivities (relative to stable reference isotopes) in meteorites vary as a function of their mean lifetimes squared. This relationship applies to chondrites, achondrites, and irons but to calcium-aluminum inclusions (CAIs). Certain meteorites contain excesses in isotopic abundances from the decay of radioactive isotopes with half-lives much less than the age of the solar system. These short-lived radioactivities are now extinct, but they were alive when meteorites assembled in the early solar system. The origin of these radioactivities and the processes which control their abundances in the solar nebula are still not well understood. Some clues may come from our finding that the meteoritic abundances of now extinct radioactivities (relative to stable reference isotopes) vary as a function of their mean lifetimes squared. This relationship applies to chondrites, achondrites, and irons, but not to CAIs. This points to at least two different processes establishing the abundances of short-lived isotopes found in the meteoritic record.

ABUNDANCES IN THE LOCAL REGION. I. G AND K GIANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luck, R. Earle, E-mail: rel2@case.edu

2015-09-15

Parameters and abundances for 1133 stars of spectral types F, G, and K of luminosity class III have been derived. In terms of stellar parameters, the primary point of interest is the disagreement between gravities derived with masses determined from isochrones, and gravities determined from an ionization balance. This is not a new result per se, but the size of this sample emphasizes the severity of the problem. A variety of arguments led to the selection of the ionization-balance gravity as the working value. The derived abundances indicate that the giants in the solar region have Sun-like total abundances andmore » abundance ratios. Stellar evolution indicators have also been investigated with the Li abundances and the [C/Fe] and C/O ratios, indicating that standard processing has been operating in these stars. The more salient result for stellar evolution is that the [C/Fe] data across the red-giant clump indicates the presence of mass-dependent mixing in accord with standard stellar evolution predictions.« less

Overview for the reanalysis of Mariner 9 UV spectrometer data for ozone, cloud, and dust abundances, and their interaction over climate timescales

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1992-01-01

Mariner 9 UV spectrometer data were reinverted for the ozone abundance, cloud abundance, dust abundance, and polar-cap albedo. The original reduction of the spectra ignored the presence of atmospheric dust and clouds, even though their abundance is substantial and can mask appreciable amounts of ozone if not accounted for (Lindner, 1988). The Mariner 9 ozone data has been used as a benchmark in all theoretical models of atmospheric composition, escape, and photochemistry. A second objective is to examine the data for the interrelationship of the ozone cycle, dust cycle, and cloud cycle, on an annual, inter-annual, and climatic basis, testing predictions by Lindner (1988). This also has implications for many terrestrial ozone studies, such as the ozone hole, acid rain, and ozone-smog. A third objective is to evaluate the efficacy of the reflectance spectroscopy technique at retrieving the ozone abundance on Mars. This would be useful for planning ozone observations on future Mars missions or the terrestrial troposphere.

Modeling the effects of fire severity and spatial complexity on Small Mammals in Yosemite National Park, California

USGS Publications Warehouse

Roberts, Susan L.; Van Wagtendonk, Jan W.; Miles, A. Keith; Kelt, Douglas A.; Lutz, James A.

2008-01-01

We evaluated the impact of fire severity and related spatial and vegetative parameters on small mammal populations in 2 yr- to 15 yr-old burns in Yosemite National Park, California, USA. We also developed habitat models that would predict small mammal responses to fires of differing severity. We hypothesized that fire severity would influence the abundances of small mammals through changes in vegetation composition, structure, and spatial habitat complexity. Deer mouse (Peromyscus maniculatus) abundance responded negatively to fire severity, and brush mouse (P. boylii) abundance increased with increasing oak tree (Quercus spp.) cover. Chipmunk (Neotamias spp.) abundance was best predicted through a combination of a negative response to oak tree cover and a positive response to spatial habitat complexity. California ground squirrel (Spermophilus beecheyi) abundance increased with increasing spatial habitat complexity. Our results suggest that fire severity, with subsequent changes in vegetation structure and habitat spatial complexity, can influence small mammal abundance patterns.

Marine litter in the upper São Vicente submarine canyon (SW Portugal): Abundance, distribution, composition and fauna interactions.

PubMed

Oliveira, Frederico; Monteiro, Pedro; Bentes, Luis; Henriques, Nuno Sales; Aguilar, Ricardo; Gonçalves, Jorge M S

2015-08-15

Marine litter has become a worldwide environmental problem, tainting all ocean habitats. The abundance, distribution and composition of litter and its interactions with fauna were evaluated in the upper S. Vicente canyon using video images from 3 remote operated vehicle exploratory dives. Litter was present in all dives and the abundance was as high as 3.31 items100m(-1). Mean abundance of litter over rock bottom was higher than on soft substrate. Mean litter abundance was slightly higher than reported for other canyons on the Portuguese margin, but lower in comparison to more urbanized coastal areas of the world. Lost fishing gear was the prevalent type of litter, indicating that the majority of litter originates from maritime sources, mainly fishing activity. Physical contact with sessile fauna and entanglement of specimens were the major impacts of lost fishing gear. Based on the importance of this region for the local fishermen, litter abundance is expected to increase. Copyright © 2015 Elsevier Ltd. All rights reserved.

Differential effects of habitat complexity, predators and competitors on abundance of juvenile and adult coral reef fishes.

PubMed

Almany, Glenn R

2004-09-01

Greater structural complexity is often associated with greater abundance and diversity, perhaps because high complexity habitats reduce predation and competition. Using 16 spatially isolated live-coral reefs in the Bahamas, I examined how abundance of juvenile (recruit) and adult (non-recruit) fishes was affected by two factors: (1) structural habitat complexity and (2) the presence of predators and interference competitors. Manipulating the abundance of low and high complexity corals created two levels of habitat complexity, which was cross-factored with the presence or absence of resident predators (sea basses and moray eels) plus interference competitors (territorial damselfishes). Over 60 days, predators and competitors greatly reduced recruit abundance regardless of habitat complexity, but did not affect adult abundance. In contrast, increased habitat complexity had a strong positive effect on adult abundance and a weak positive effect on recruit abundance. Differential responses of recruits and adults may be related to the differential effects of habitat complexity on their primary predators. Sedentary recruits are likely most preyed upon by small resident predators that ambush prey, while larger adult fishes that forage widely and use reefs primarily for shelter are likely most preyed upon by large transient predators that chase prey. Increased habitat complexity may have inhibited foraging by transient predators but not resident predators. Results demonstrate the importance of habitat complexity to community dynamics, which is of concern given the accelerated degradation of habitats worldwide.

Structure and Dynamics of the Shark Assemblage off Recife, Northeastern Brazil

PubMed Central

Afonso, André S.; Andrade, Humber A.; Hazin, Fábio H. V.

2014-01-01

Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean. PMID:25010514

Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

PubMed

Afonso, André S; Andrade, Humber A; Hazin, Fábio H V

2014-01-01

Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean.

Impact of valley fills on streamside salamanders in southern West Virginia

USGS Publications Warehouse

Wood, Petra Bohall; Williams, Jennifer M.

2013-01-01

Valley fills associated with mountaintop-removal mining bury stream headwaters and affect water quality and ecological function of reaches below fills. We quantified relative abundance of streamside salamanders in southern West Virginia during 2002 in three streams below valley fills (VFS) and in three reference streams (RS). We surveyed 36 10- × 2-m stream transects, once in summer and fall, paired by order and structure. Of 2,343 salamanders captured, 66.7% were from RS. Total salamanders (adults plus larvae) were more abundant in RS than VFS for first-order and second-order reaches. Adult salamanders had greater abundance in first-order reaches of RS than VFS. Larval salamanders were more abundant in second-order reaches of RS than VFS. No stream width or mesohabitat variables differed between VFS and RS. Only two cover variables differed. Silt cover, greater in VFS than RS first-order reaches, is a likely contributor to reduced abundance of salamanders in VFS. Second-order RS had more boulder cover than second-order VFS, which may have contributed to the higher total and larval salamander abundance in RS. Water chemistry assessments of our VFS and RS reported elevated levels of metal and ion concentrations in VFS, which can depress macroinvertebrate populations and likely affect salamander abundance. Valley fills appear to have significant negative effects on stream salamander abundance due to alterations in habitat structure, water quality and chemistry, and macroinvertebrate communities in streams below fills.

Distinct succession patterns of abundant and rare bacteria in temporal microcosms with pollutants.

PubMed

Jiao, Shuo; Luo, Yantao; Lu, Mingmei; Xiao, Xiao; Lin, Yanbing; Chen, Weimin; Wei, Gehong

2017-06-01

Elucidating the driving forces behind the temporal dynamics of abundant and rare microbes is essential for understanding the assembly and succession of microbial communities. Here, we explored the successional trajectories and mechanisms of abundant and rare bacteria via soil-enrichment subcultures in response to various pollutants (phenanthrene, n-octadecane, and CdCl 2 ) using time-series Illumina sequencing datasets. The results reveal different successional patterns of abundant and rare sub-communities in eighty pollutant-degrading consortia and two original soil samples. A temporal decrease in α-diversity and high turnover rate for β-diversity indicate that deterministic processes are the main drivers of the succession of the abundant sub-community; however, the high cumulative species richness indicates that stochastic processes drive the succession of the rare sub-community. A functional prediction showed that abundant bacteria contribute primary functions to the pollutant-degrading consortia, such as amino acid metabolism, cellular responses to stress, and hydrocarbon degradation. Meanwhile, rare bacteria contribute a substantial fraction of auxiliary functions, such as carbohydrate-active enzymes, fermentation, and homoacetogenesis, which indicates their roles as a source of functional diversity. Our study suggests that the temporal succession of microbes in polluted microcosms is mainly associated with abundant bacteria rather than the high proportion of rare taxa. The major forces (i.e., stochastic or deterministic processes) driving microbial succession could be dependent on the low- or high-abundance community members in temporal microcosms with pollutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Abundance of Pink-Pigmented Facultative Methylotrophs in the Root Zone of Plant Species in Invaded Coastal Sage Scrub Habitat

PubMed Central

Irvine, Irina C.; Brigham, Christy A.; Suding, Katharine N.; Martiny, Jennifer B. H.

2012-01-01

Pink-pigmented facultative methylotrophic bacteria (PPFMs) are associated with the roots, leaves and seeds of most terrestrial plants and utilize volatile C1 compounds such as methanol generated by growing plants during cell division. PPFMs have been well studied in agricultural systems due to their importance in crop seed germination, yield, pathogen resistance and drought stress tolerance. In contrast, little is known about the PPFM abundance and diversity in natural ecosystems, let alone their interactions with non-crop species. Here we surveyed PPFM abundance in the root zone soil of 5 native and 5 invasive plant species along ten invasion gradients in Southern California coastal sage scrub habitat. PPFMs were present in every soil sample and ranged in abundance from 102 to 105 CFU/g dry soil. This abundance varied significantly among plant species. PPFM abundance was 50% higher in the root zones of annual or biennial species (many invasives) than perennial species (all natives). Further, PPFM abundance appears to be influenced by the plant community beyond the root zone; pure stands of either native or invasive species had 50% more PPFMs than mixed species stands. In sum, PPFM abundance in the root zone of coastal sage scrub plants is influenced by both the immediate and surrounding plant communities. The results also suggest that PPFMs are a good target for future work on plant-microorganism feedbacks in natural ecosystems. PMID:22383990

The abundance of pink-pigmented facultative methylotrophs in the root zone of plant species in invaded coastal sage scrub habitat.

PubMed

Irvine, Irina C; Brigham, Christy A; Suding, Katharine N; Martiny, Jennifer B H

2012-01-01

Pink-pigmented facultative methylotrophic bacteria (PPFMs) are associated with the roots, leaves and seeds of most terrestrial plants and utilize volatile C(1) compounds such as methanol generated by growing plants during cell division. PPFMs have been well studied in agricultural systems due to their importance in crop seed germination, yield, pathogen resistance and drought stress tolerance. In contrast, little is known about the PPFM abundance and diversity in natural ecosystems, let alone their interactions with non-crop species. Here we surveyed PPFM abundance in the root zone soil of 5 native and 5 invasive plant species along ten invasion gradients in Southern California coastal sage scrub habitat. PPFMs were present in every soil sample and ranged in abundance from 10(2) to 10(5) CFU/g dry soil. This abundance varied significantly among plant species. PPFM abundance was 50% higher in the root zones of annual or biennial species (many invasives) than perennial species (all natives). Further, PPFM abundance appears to be influenced by the plant community beyond the root zone; pure stands of either native or invasive species had 50% more PPFMs than mixed species stands. In sum, PPFM abundance in the root zone of coastal sage scrub plants is influenced by both the immediate and surrounding plant communities. The results also suggest that PPFMs are a good target for future work on plant-microorganism feedbacks in natural ecosystems.

Environmental and Biotic Correlates to Lionfish Invasion Success in Bahamian Coral Reefs

PubMed Central

Anton, Andrea; Simpson, Michael S.; Vu, Ivana

2014-01-01

Lionfish (Pterois volitans), venomous predators from the Indo-Pacific, are recent invaders of the Caribbean Basin and southeastern coast of North America. Quantification of invasive lionfish abundances, along with potentially important physical and biological environmental characteristics, permitted inferences about the invasion process of reefs on the island of San Salvador in the Bahamas. Environmental wave-exposure had a large influence on lionfish abundance, which was more than 20 and 120 times greater for density and biomass respectively at sheltered sites as compared with wave-exposed environments. Our measurements of topographic complexity of the reefs revealed that lionfish abundance was not driven by habitat rugosity. Lionfish abundance was not negatively affected by the abundance of large native predators (or large native groupers) and was also unrelated to the abundance of medium prey fishes (total length of 5–10 cm). These relationships suggest that (1) higher-energy environments may impose intrinsic resistance against lionfish invasion, (2) habitat complexity may not facilitate the lionfish invasion process, (3) predation or competition by native fishes may not provide biotic resistance against lionfish invasion, and (4) abundant prey fish might not facilitate lionfish invasion success. The relatively low biomass of large grouper on this island could explain our failure to detect suppression of lionfish abundance and we encourage continuing the preservation and restoration of potential lionfish predators in the Caribbean. In addition, energetic environments might exert direct or indirect resistance to the lionfish proliferation, providing native fish populations with essential refuges. PMID:25184250

Environmental and biotic correlates to lionfish invasion success in Bahamian coral reefs.

PubMed

Anton, Andrea; Simpson, Michael S; Vu, Ivana

2014-01-01

Lionfish (Pterois volitans), venomous predators from the Indo-Pacific, are recent invaders of the Caribbean Basin and southeastern coast of North America. Quantification of invasive lionfish abundances, along with potentially important physical and biological environmental characteristics, permitted inferences about the invasion process of reefs on the island of San Salvador in the Bahamas. Environmental wave-exposure had a large influence on lionfish abundance, which was more than 20 and 120 times greater for density and biomass respectively at sheltered sites as compared with wave-exposed environments. Our measurements of topographic complexity of the reefs revealed that lionfish abundance was not driven by habitat rugosity. Lionfish abundance was not negatively affected by the abundance of large native predators (or large native groupers) and was also unrelated to the abundance of medium prey fishes (total length of 5-10 cm). These relationships suggest that (1) higher-energy environments may impose intrinsic resistance against lionfish invasion, (2) habitat complexity may not facilitate the lionfish invasion process, (3) predation or competition by native fishes may not provide biotic resistance against lionfish invasion, and (4) abundant prey fish might not facilitate lionfish invasion success. The relatively low biomass of large grouper on this island could explain our failure to detect suppression of lionfish abundance and we encourage continuing the preservation and restoration of potential lionfish predators in the Caribbean. In addition, energetic environments might exert direct or indirect resistance to the lionfish proliferation, providing native fish populations with essential refuges.

Composition of fungal soil communities varies with plant abundance and geographic origin

PubMed Central

Reininger, Vanessa; Martinez-Garcia, Laura B.; Sanderson, Laura; Antunes, Pedro M.

2015-01-01

Interactions of belowground fungal communities with exotic and native plant species may be important drivers of plant community structure in invaded grasslands. However, field surveys linking plant community structure with belowground fungal communities are missing. We investigated whether a selected number of abundant and relatively rare plants, either native or exotic, from an old-field site associate with different fungal communities. We also assessed whether these plants showed different symbiotic relationships with soil biota through their roots. We characterized the plant community and collected roots to investigate fungal communities using 454 pyrosequencing and assessed arbuscular mycorrhizal colonization and enemy-induced lesions. Differences in fungal communities were considered based on the assessment of α- and β diversity depending on plant ‘abundance’ and ‘origin’. Plant abundance and origin determined the fungal community. Fungal richness was higher for native abundant as opposed to relatively rare native plant species. However, this was not observed for exotics of contrasting abundance. Regardless of their origin, β diversity was higher for rare than for abundant species. Abundant exotics in the community, which happen to be grasses, were the least mycorrhizal whereas rare natives were most susceptible to enemy attack. Our results suggest that compared with exotics, the relative abundance of remnant native plant species in our old-field site is still linked to the structure of belowground fungal communities. In contrast, exotic species may act as a disturbing agent contributing towards the homogenization of soil fungal communities, potentially changing feedback interactions. PMID:26371291

Interactions between plants and primates shape community diversity in a rainforest in Madagascar.

PubMed

Herrera, James P

2016-07-01

Models of ecological community assembly predict how communities of interacting organisms may be shaped by abiotic and biotic factors. Competition and environmental filtering are the predominant factors hypothesized to explain community assembly. This study tested the effects of habitat, phylogenetic and phenotypic trait predictors on species co-occurrence patterns and abundances, with the endemic primates of Madagascar as an empirical system. The abundance of 11 primate species was estimated along gradients of elevation, food resource abundance and anthropogenic habitat disturbance at local scales in south-east Madagascar. Community composition was compared to null models to test for phylogenetic and functional structure, and the effects of phylogenetic relatedness of co-occurring species, their trait similarity and environmental variables on species' abundances were tested using mixed models and quantile regressions. Resource abundance was the strongest predictor of community structure. Where food tree abundance was high, closely related species with similar traits dominated communities. High-elevation communities with lower food tree abundance consisted of species that were distantly related and had divergent traits. Closely related species had dissimilar abundances where they co-occurred, partially driven by trait dissimilarity, indicating character displacement. By integrating local-scale variation in primate community composition, evolutionary relatedness and functional diversity, this study found strong evidence that community assembly in this system can be explained by competition and character displacement along ecological gradients. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Effects of protective fencing on birds, lizards, and black-tailed hares in the Western Mojave Desert

USGS Publications Warehouse

Brooks, M.

1999-01-01

Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995 at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high than a low rainfall year. Ash-throated flycatchers (Myiarchus cinerascens), cactus wrens (Campylorhynchus brunneicapillus), LeConte's thrashers (Toxostoma lecontei), loggerhead shrikes (Lanius ludovicianus), sage sparrows (Amphispiza belli), and verdins (Auriparus flaviceps) were more abundant inside than outside the DTNA. Nesting activity was also more frequent inside. Total abundance and species richness of lizards and individual abundances of western whiptail lizards (Cnemidophorous tigris) and desert spiny lizards (Sceloporus magister) were higher inside than outside. In contrast, abundance of black-tailed hares was lower inside. Structural diversity of the perennial plant community did not differ due to protection, but cover was 50% higher in protected areas. Black-tailed hares generally prefer areas of low perennial plant cover, which may explain why they were more abundant outside than inside the DTNA. Habitat structure may not affect bird and lizard communities as much as availability of food at this desert site, and the greater abundance and species richness of vertebrates inside than outside the DTNA may correlate with abundances of seeds and invertebrate prey.

Comparing Effects of Lake- and Watershed-Scale Influences on Communities of Aquatic Invertebrates in Shallow Lakes

PubMed Central

Hanson, Mark A.; Herwig, Brian R.; Zimmer, Kyle D.; Fieberg, John; Vaughn, Sean R.; Wright, Robert G.; Younk, Jerry A.

2012-01-01

Constraints on lake communities are complex and are usually studied by using limited combinations of variables derived from measurements within or adjacent to study waters. While informative, results often provide limited insight about magnitude of simultaneous influences operating at multiple scales, such as lake- vs. watershed-scale. To formulate comparisons of such contrasting influences, we explored factors controlling the abundance of predominant aquatic invertebrates in 75 shallow lakes in western Minnesota, USA. Using robust regression techniques, we modeled relative abundance of Amphipoda, small and large cladocera, Corixidae, aquatic Diptera, and an aggregate taxon that combined Ephemeroptera-Trichoptera-Odonata (ETO) in response to lake- and watershed-scale characteristics. Predictor variables included fish and submerged plant abundance, linear distance to the nearest wetland or lake, watershed size, and proportion of the watershed in agricultural production. Among-lake variability in invertebrate abundance was more often explained by lake-scale predictors than by variables based on watershed characteristics. For example, we identified significant associations between fish presence and community type and abundance of small and large cladocera, Amphipoda, Diptera, and ETO. Abundance of Amphipoda, Diptera, and Corixidae were also positively correlated with submerged plant abundance. We observed no associations between lake-watershed variables and abundance of our invertebrate taxa. Broadly, our results seem to indicate preeminence of lake-level influences on aquatic invertebrates in shallow lakes, but historical land-use legacies may mask important relationships. PMID:22970275

Abundance matters: a field experiment testing the more individuals hypothesis for richness–productivity relationships

PubMed Central

Yee, D. A.; Juliano, S. A.

2007-01-01

The more individuals hypothesis (MIH) postulates that productivity increases species richness by increasing mean equilibrium population size, thereby reducing the probability of local extinction. We tested the MIH for invertebrates colonizing microcosms that simulated tree holes by manipulating productivity through additions of leaf or animal detritus and subsequently determining the relationships among richness, total abundance, abundance per species, and measures of productivity. We quantified productivity as the rate of microorganism protein synthesis, microorganism metabolic rate, nutrient ion concentration, and type and amount of detritus. Microcosms with animal detritus attracted more species, more individuals per species, and more total individuals than did microcosms with similar amounts of leaf detritus. Relationships between richness or abundance and productivity varied with date. Richness in June increased as a linear function of productivity, whereas the power function predicted by the MIH fit best in July. Abundance in June and July was best described by a power function of productivity, but the linear function predicted by the MIH fit best in September. Abundance per species was best described by a power function of productivity in June and July. Path analysis showed that the indirect effect of productivity through abundance on richness that is predicted by MIH was important in all months, and that direct links between productivity and richness were unnecessary. Our results support many of the predictions of the MIH, but they also suggest that the effects of abundance on richness may be more complex than expected. PMID:17401581

Effect from low-level exposure of oxytetracycline on abundance of tetracycline resistance genes in arable soils.

PubMed

Shentu, Jia-Li; Zhang, Kun; Shen, Dong-Sheng; Wang, Mei-Zhen; Feng, Hua-Jun

2015-09-01

To evaluate the effect from low-level exposure of antibiotics on the abundance of antibiotic resistance genes, unpolluted arable soils were treated with oxytetracycline (OTC)-containing manure, with OTC (0, 2, 20, or 70 μg kg(-1)) added every 2 weeks on 10 occasions. Six tetracycline resistance genes [TRGs-tet(A), tet(L), tet(M), tet(Q), tet(O), and tet(W)] and the 16S ribosomal RNA (rRNA) gene were monitored using real-time quantitative polymerase chain reaction. The relative abundance of tet(A), tet(L), tet(M), and tet(Q) genes in soil increased 10-1000 times after application of OTC-containing manure. Tet(A) abundance per unit of residual OTC on day 140 was 1.53-4.42 times higher than that on day 28, while tet(L) abundance was 1.04-1.74 times higher. Treatment with >40 μg kg(-1) OTC significantly increased abundance of tet(A) and tet(L), while tet(M) and tet(Q) abundance was positively correlated (R (2) = 0.965 and 0.932, p < 0.01) with residual OTC concentrations. There was a significant accumulation of TRGs associated with low-level OTC exposure in arable soils. Besides OTC residual, the effects from exposure time and application frequencies should also be considered to limit the increase in abundance of tet(A) and tet(L).

Estimating wetland vegetation abundance from Landsat-8 operational land imager imagery: a comparison between linear spectral mixture analysis and multinomial logit modeling methods

NASA Astrophysics Data System (ADS)

Zhang, Min; Gong, Zhaoning; Zhao, Wenji; Pu, Ruiliang; Liu, Ke

2016-01-01

Mapping vegetation abundance by using remote sensing data is an efficient means for detecting changes of an eco-environment. With Landsat-8 operational land imager (OLI) imagery acquired on July 31, 2013, both linear spectral mixture analysis (LSMA) and multinomial logit model (MNLM) methods were applied to estimate and assess the vegetation abundance in the Wild Duck Lake Wetland in Beijing, China. To improve mapping vegetation abundance and increase the number of endmembers in spectral mixture analysis, normalized difference vegetation index was extracted from OLI imagery along with the seven reflective bands of OLI data for estimating the vegetation abundance. Five endmembers were selected, which include terrestrial plants, aquatic plants, bare soil, high albedo, and low albedo. The vegetation abundance mapping results from Landsat OLI data were finally evaluated by utilizing a WorldView-2 multispectral imagery. Similar spatial patterns of vegetation abundance produced by both fully constrained LSMA algorithm and MNLM methods were observed: higher vegetation abundance levels were distributed in agricultural and riparian areas while lower levels in urban/built-up areas. The experimental results also indicate that the MNLM model outperformed the LSMA algorithm with smaller root mean square error (0.0152 versus 0.0252) and higher coefficient of determination (0.7856 versus 0.7214) as the MNLM model could handle the nonlinear reflection phenomenon better than the LSMA with mixed pixels.

Spatial abundance models and seasonal distribution for guanaco (Lama guanicoe) in central Tierra del Fuego, Argentina.

PubMed

Flores, Celina E; Deferrari, Guillermo; Collado, Leonardo; Escobar, Julio; Schiavini, Adrián

2018-01-01

Spatially explicit modelling allows to estimate population abundance and predict species' distribution in relation to environmental factors. Abiotic factors are the main determinants of a herbivore´s response to environmental heterogeneity on large spatiotemporal scales. We assessed the influence of elevation, geographic location and distance to the coast on the seasonal abundance and distribution of guanaco (Lama guanicoe) in central Tierra del Fuego, by means of spatially explicit modelling. The estimated abundance was 23,690 individuals for the non-breeding season and 33,928 individuals for the breeding season. The factors influencing distribution and abundance revealed to be the elevation for the non-breeding season, and the distance to the coast and geographic location for the breeding season. The southwest of the study area presented seasonal abundance variation and the southeast and northeast presented high abundance during both seasons. The elevation would be the driving factor of guanaco distribution, as individuals move to lower areas during the non-breeding season and ascend to high areas during the breeding season. Our results confirm that part of the guanaco population performs seasonal migratory movements and that the main valleys present important wintering habitats for guanacos as well as up-hill zones during summer. This type of study would help to avoid problems of scale mismatch and achieve better results in management actions and is an example of how to assess important seasonal habitats from evaluations of abundance and distribution patterns.

Spatial abundance models and seasonal distribution for guanaco (Lama guanicoe) in central Tierra del Fuego, Argentina

PubMed Central

Deferrari, Guillermo; Collado, Leonardo; Escobar, Julio; Schiavini, Adrián

2018-01-01

Spatially explicit modelling allows to estimate population abundance and predict species’ distribution in relation to environmental factors. Abiotic factors are the main determinants of a herbivore´s response to environmental heterogeneity on large spatiotemporal scales. We assessed the influence of elevation, geographic location and distance to the coast on the seasonal abundance and distribution of guanaco (Lama guanicoe) in central Tierra del Fuego, by means of spatially explicit modelling. The estimated abundance was 23,690 individuals for the non-breeding season and 33,928 individuals for the breeding season. The factors influencing distribution and abundance revealed to be the elevation for the non-breeding season, and the distance to the coast and geographic location for the breeding season. The southwest of the study area presented seasonal abundance variation and the southeast and northeast presented high abundance during both seasons. The elevation would be the driving factor of guanaco distribution, as individuals move to lower areas during the non-breeding season and ascend to high areas during the breeding season. Our results confirm that part of the guanaco population performs seasonal migratory movements and that the main valleys present important wintering habitats for guanacos as well as up-hill zones during summer. This type of study would help to avoid problems of scale mismatch and achieve better results in management actions and is an example of how to assess important seasonal habitats from evaluations of abundance and distribution patterns. PMID:29782523

Seasonal distribution and abundance of cetaceans within French waters- Part I: The North-Western Mediterranean, including the Pelagos sanctuary

NASA Astrophysics Data System (ADS)

Laran, Sophie; Pettex, Emeline; Authier, Matthieu; Blanck, Aurélie; David, Léa; Dorémus, Ghislain; Falchetto, Hélène; Monestiez, Pascal; Van Canneyt, Olivier; Ridoux, Vincent

2017-07-01

The biodiversity of the Mediterranean Sea is undergoing important changes. Cetaceans, as top predators, are an important component of marine ecosystems. The seasonal distribution and abundance of several cetacean species were studied with a large aerial survey over the North-Western Mediterranean Sea, including the international Pelagos sanctuary, the largest Marine Protected Area (MPA) designed for marine mammals in the Mediterranean. A total of 8 distinct species of cetaceans were identified, and their occurrence within the sanctuary was investigated. Abundance estimates were obtained for three groups of species: the small delphinids (striped dolphins mainly), the bottlenose dolphin and the fin whale. There was a seasonal variation in striped dolphin abundance between winter (57,300 individuals, 95% CI: 34,500-102,000) and summer (130,000, 95% CI: 76,800-222,100). In contrast, bottlenose dolphin winter abundance was thrice that of summer. It was also the only species to exhibit any preference for the Pelagos sanctuary. Fin whale abundance had the reverse pattern with winter abundance (1000 individuals, 95% CI: 500-2500) and summer (2500 individuals, 95% CI: 1500-4300), without any preference for the sanctuary. Risso's dolphins, pilot whales and sperm whales did not exhibit strong seasonal pattern in their abundance. These results provide baseline estimates which can be used to inform conservation policies and instruments such as the Habitats Directive or the recent European Marine Strategy Framework Directive.

LITHIUM IN THE UPPER CENTAURUS LUPUS AND LOWER CENTAURUS CRUX SUBGROUPS OF SCORPIUS-CENTAURUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bubar, Eric J.; Schaeuble, Marc; King, Jeremy R.

2011-12-15

We utilize spectroscopically derived model atmosphere parameters and the Li I {lambda}6104 subordinate line and the {lambda}6708 doublet to derive lithium abundances for 12 members of the Upper Centaurus Lupus and Lower Centaurus Crux subgroups of the Scorpius-Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9-1.4 M{sub Sun} stars is limited to {approx}0.15 dex, consistent with the lack of dispersion in {>=}1.0 M{sub Sun} stars in the 100 Myr Pleiades and 30-50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the {lambda}6104 line yields abundances withmore » equivalent or less scatter than is found from the {lambda}6708 doublet as a result of lower uncertainties for the subordinate feature, a result of low sensitivity to broadening in the subordinate feature. Because non-local thermodynamic equilibrium (NLTE) corrections are less susceptible to changes in surface gravity and/or metallicity for the 6104 A line, the subordinate Li feature is preferred for deriving lithium abundances in young Li-rich stellar association stars with T{sub eff} {>=} 5200 K. At these temperatures, we find no difference between the Li abundances derived from the two Li I lines. For cooler stars, having temperatures at which main-sequence dwarfs show abundance patterns indicating overexcitation and overionization, the {lambda}6104-based Li abundances are {approx}0.4 dex lower than those derived from the {lambda}6708 doublet. The trends of the abundances from each feature with T{sub eff} suggest that this difference is due to (near)UV photoionization, which in NLTE preferentially ionizes Li atoms in the subordinate 2p state relative to the 2s resonance line state due to opacity effects. Consequently, this overionization of Li in the 2p state, apparently not adequately accounted for in NLTE corrections, weakens the {lambda}6104 feature in cooler stars. Accordingly, the {lambda}6708-based abundances may give more reliable estimates of the mean Li abundance in cool young stars. Our mean Li abundance, log N(Li) =3.50 {+-} 0.07 is {approx}0.2 dex larger than the meteoritic value. While stellar models suggest that Li depletion of at least 0.4 dex, and possibly much larger, should have occurred in our lowest mass star(s), our Li abundances show no decline with decreasing mass indicative of such depletion.« less

Spring evolution of Pseudocalanus spp. abundance on Georges Bank based on molecular discrimination of P. moultoni and P. newmani1

NASA Astrophysics Data System (ADS)

Bucklin, Ann; Guarnieri, Maria; McGillicuddy, Dennis J.; Sean Hill, R.

The planktonic copepod sibling species Pseudocalanus moultoni and P. newmani (Crustacea, Copepoda) are abundant in waters over Georges Bank from late winter until mid-summer and are thought to reproduce throughout this period. The two species cannot be reliably distinguished using morphological characters, but are readily identified and distinguished by simple, rapid, and inexpensive molecular protocols based on sequence variation of mitochondrial DNA (mtDNA). DNA sequence variation of a portion of the mitochondrial cytochrome oxidase I (mtCOI) confirmed the presence of P. moultoni and P. newmani on Georges Bank; the mtCOI sequences were used to design species-specific oligonucleotide primers for use in a competitive multiplexed species-specific polymerase chain reaction (PCR). Species-specific PCR was used to determine the relative abundances of the two species in sub-samples of zooplankton collections from US GLOBEC Georges Bank Study Broadscale Surveys from February to June, 1997. Based on monthly visualizations, we inferred the spring evolution of the two species' distributions and abundances on Georges Bank. Both species' overall abundances increased from February to May or June: maximum abundance of P. moultoni was 38,061 m -2 in surface waters on the crest of Georges Bank in June; maximum abundance of P. newmani was 13,854 m -2 in subsurface waters on the Northeast Peak in April. The Peak in distribution of P. moultoni shifted from Georges Basin in April, to the northern edge of the Bank in May, to the center of the Bank in June. In contrast, P. newmani was more abundant to the south and east of the Bank. Beginning in April, P. newmani occurred on the Bank but was less abundant and less widely-distributed than P. moultoni; P. newmani abundance peaked in May and declined somewhat in June. Females of the species differed in their patterns of distribution and abundance, with P. moultoni always the more abundant species on the crest of the Bank. The spring increase of P. moultoni may result from the persistence of reproducing individuals over the Bank and/or from advective transport from adjacent regions. In contrast, P. newmani may be transported to Georges Bank from upstream populations on the Scotian Shelf and Browns Bank. The processes responsible for the observed patterns cannot be determined from this series of monthly snap-shots alone; ongoing studies use numerical models to examine the biological and physical dynamics causing these distributions.

CORRELATION OF RED-SHOULDERED HAWK ABUNDANCE AND MACROHABITAT CHARACTERISTICS IN SOUTHERN OHIO

EPA Science Inventory

We measured an index of Red-shouldered Hawk (Buteo lineatus) abundance along streams in southern Ohio and related differences in abundance index to landscape scale habitat characteristics within the surveyed areas. Fifteen study sites, each a 5.8-km reach of permanent stream, we...

Mechanisms driving postfire abundance of a generalist mammal

Treesearch

R. Zwolak; D. E. Pearson; Y. K. Ortega; E. E. Crone

2012-01-01

Changes in vertebrate abundance following disturbance are commonly attributed to shifts in food resources or predation pressure, but underlying mechanisms have rarely been tested. We examined four hypotheses for the commonly reported increase in abundance of deer mouse (Peromyscus maniculatus (Wagner, 1845)) following forest fires: source-sink dynamics, decreased...

Classifying rarity and abundance at a regional scale: Implementation within a new ecoinformatics tool

EPA Science Inventory

One factor that determines a species vulnerability to extinction is its rarity in the environment and a goal of many species analyses is to evaluate geographic patterns of abundance. In an attempt to assess vulnerability to climate change, we evaluated relative species abundance...

VARIATION IN JUVENILE COHO SALMON SUMMER ABUNDANCE: HIERARCHICAL ANALYSIS OF HABITAT EFFECTS

EPA Science Inventory

Varying habitat conditions found across a stream network during the summer months may limit the abundance of salmonids such as coho (Oncorhynchus kisutch). We examined the abundance of juvenile coho salmon across a stream network in an Oregon coast range basin from 2002 through ...

HSE Abundances in Angrites and HEDs: Core-Mantle Equilibration or Late Accretion Addition of a Chondritic Component

NASA Astrophysics Data System (ADS)

Rai, N.; Downes, H.; Smith, C. L.

2016-08-01

Using metal-silicate partitioning of HSEs together with their mantle abundances in Vesta and the APB respectively, we test whether formation of a metallic core could have led to the observed abundances of the HSEs, in the mantles of these bodies.

Precision measurements of solar energetic particle elemental composition

NASA Technical Reports Server (NTRS)

Breneman, H.; Stone, E. C.

1985-01-01

Using data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft, solar energetic particle abundances or upper limits for all elements with 3 = Z = 30 from a combined set of 10 solar flares during the 1977 to 1982 time period were determined. Statistically meaningful abundances have been determined for the first time for several rare elements including P, Cl, K, Ti and Mn, while the precision of the mean abundances for the more abundant elements has been improved by typically a factor of approximately 3 over previously reported values.

An independent view?

NASA Astrophysics Data System (ADS)

Lambert, David L.

The current dispute over the oxygen abundance in metal-poor stars has been viewed from a distance by this observer who would claim a measure of independence despite an intermittent interest in oxygen abundance determinations over 3 decades. This summary attempts to persuade all participants whether they advocate a "high" or "low" oxygen abundance or are simply bemused by the dispute that in resolving the present disagreements we shall learn not only about the oxygen abundance of these oldest Galactic stars but shall achieve a deeper understanding of the atmospheres of the stars.

A guide to the use of distance sampling to estimate abundance of Karner blue butterflies

USGS Publications Warehouse

Grundel, Ralph

2015-01-01

This guide is intended to describe the use of distance sampling as a method for evaluating the abundance of Karner blue butterflies at a location. Other methods for evaluating abundance exist, including mark-release-recapture and index counts derived from Pollard-Yates surveys, for example. Although this guide is not intended to be a detailed comparison of the pros and cons of each type of method, there are important preliminary considerations to think about before selecting any method for evaluating the abundance of Karner blue butterflies.

Solar abundance of silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holweger, H.

1973-07-01

An analysis of 19 photospheric Si I lines whose oscillator strengths have recently been detertmined by Garz (1973) leads to a solar abundance of silicon, log epsilon /sub Si/ = 7.65 plus or minus 0.07, on the scale where log epsilon /sub H/ = 12. Together with the sodium abundance determained earlier by the same method, a solar abundance ratio /sup epsilon /Na//sup epsilon /Si = 0.045 ( plus or minus 10%) results. Within the error limits this a grees wtth the meteoritic ratio found in carbonaceous chondrites. Results concerning line-broadening by hydrogen are discussed. (auth)

Global Clusters as Laboratories for Stellar Evolution

NASA Technical Reports Server (NTRS)

Catelan, Marcio; Valcarce, Aldo A. R.; Sweigart, Allen V.

2010-01-01

Globular clusters have long been considered the closest approximation to a physicist's laboratory in astrophysics, and as such a near-ideal laboratory for (low-mass) stellar evolution, However, recent observations have cast a shadow on this long-standing paradigm, suggesting the presence of multiple populations with widely different abundance patterns, and - crucially - with widely different helium abundances as welL In this review we discuss which features of the Hertzsprung-Russell diagram may be used as helium abundance indicators, and present an overview of available constraints on the helium abundance in globular clusters,

Determination of the light ion abundances in the strong-helium star HR 3089

NASA Technical Reports Server (NTRS)

Lester, J. B.

1975-01-01

Using line blanketed model stellar atmospheres and a spectrum synthesis approach, a differential abundance study of the ultraviolet spectrum of HR 3089 relative to the normal star lambda Sco was performed. Both stars were found to have the same abundances of carbon and silicon, but the helium and nitrogen are significantly enhanced in HR 3089. The atmospheric parameters and the distribution of abundances found for HR 3089 agree well with the results of Osmer and Peterson on sharp-lined helium-rich stars. The rotational velocity of 160 km/sec found for HR 3089 places a constraint on the role of diffusion in producing the abundance anomalies. Examination of the resonance lines of C II, N II, Si III and Si IV shows no evidence for mass loss in either star.

Aquifer water abundance evaluation using a fuzzy- comprehensive weighting method

NASA Astrophysics Data System (ADS)

Wei, Z.

2016-08-01

Aquifer water abundance evaluation is a highly relevant issue that has been researched for many years. Despite prior research, problems with the conventional evaluation method remain. This paper establishes an aquifer water abundance evaluation method that combines fuzzy evaluation with a comprehensive weighting method to overcome both the subjectivity and lack of conformity in determining weight by pure data analysis alone. First, this paper introduces the principle of a fuzzy-comprehensive weighting method. Second, the example of well field no. 3 (of a coalfield) is used to illustrate the method's process. The evaluation results show that this method is can more suitably meet the real requirements of aquifer water abundance assessment, leading to more precise and accurate evaluations. Ultimately, this paper provides a new method for aquifer water abundance evaluation.

OXYGEN ABUNDANCES IN CEPHEIDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luck, R. E.; Andrievsky, S. M.; Korotin, S. N.

2013-07-01

Oxygen abundances in later-type stars, and intermediate-mass stars in particular, are usually determined from the [O I] line at 630.0 nm, and to a lesser extent, from the O I triplet at 615.7 nm. The near-IR triplets at 777.4 nm and 844.6 nm are strong in these stars and generally do not suffer from severe blending with other species. However, these latter two triplets suffer from strong non-local thermodynamic equilibrium (NLTE) effects and thus see limited use in abundance analyses. In this paper, we derive oxygen abundances in a large sample of Cepheids using the near-IR triplets from an NLTEmore » analysis, and compare those abundances to values derived from a local thermodynamic equilibrium (LTE) analysis of the [O I] 630.0 nm line and the O I 615.7 nm triplet as well as LTE abundances for the 777.4 nm triplet. All of these lines suffer from line strength problems making them sensitive to either measurement complications (weak lines) or to line saturation difficulties (strong lines). Upon this realization, the LTE results for the [O I] lines and the O I 615.7 nm triplet are in adequate agreement with the abundance from the NLTE analysis of the near-IR triplets.« less

Corrigendum to "Community composition of picoeukaryotes in the South China Sea during winter" [Cont. Shelf Res. 143 (2017) 91-100

NASA Astrophysics Data System (ADS)

Lin, Yun-Chi; Chiang, Kuo-Ping; Kang, Lee-Kuo

2018-06-01

The authors regret that Table 1 in the above article contained incorrect exponents in reporting the abundances of Synechococcus and photosynthetic picoeukaryotes. In these abundances expressed in scientific notation, the correct order of magnitude should be "× 1011" instead of "× 108". The correct Table 1 is displayed here. In addition, values reported in the first paragraph (environmental parameters) of Results and Discussion should be changed to "Based on data from flow cytometry, Synechococcus was the most abundant picophytoplankton, with an integrated abundance in the upper 100 m ranging from 3.05 × 1011 cell m-2 to 9.41 × 1011 cell m-2. Abundance of photosynthetic picoeukaryotes was slightly lower, ranging from 0.88 × 1011 cell m-2 to 1.67 × 1011 cell m-2". The corrected values are consistent with the integrated abundances of Synechococcus and picoeukaryotes reported in the Southeast Asia Time-series Station in the South China Sea (Liu et al., 2007). Since this study emphasizes on the community composition of picoeukaryotes, these changes do not affect the main conclusions of the article. We would like to thank Chih-Ching Chung who kindly reminded us about the low values of integrated abundance of Synechococcus and photosynthetic picoeukaryotes.

Pathogenic Streptomyces spp. abundance affected by potato cultivars.

PubMed

Nahar, Kamrun; Goyer, Claudia; Zebarth, Bernie J; Burton, David L; Whitney, Sean

2018-04-16

Potato cultivars vary in their tolerance to common scab (CS), however how they affect CS-causing Streptomyces spp. populations over time is poorly understood. This study investigated the effects of potato cultivar on pathogenic Streptomyces spp. abundance, measured using quantitative PCR, in three spatial locations in a CS-infested field: 1) soil close to the plant (SCP); 2) rhizosphere (RS); and 3) geocaulosphere (GS) soils. Two tolerant (Gold Rush, Hindenburg) and two susceptible cultivars (Green Mountain, Agria) were tested. The abundance of pathogenic Streptomyces spp. significantly increased in late August compared with other dates in RS of susceptible cultivars in both years. Abundance of pathogenic Streptomyces spp., when averaged over locations and time, was significantly greater in susceptible cultivars compared with tolerant cultivars in 2014. Principal coordinates analysis showed that SCP and RS soil properties (pH, organic carbon and nitrogen concentrations) explained 68% and 76% of total variation in Streptomyces spp. abundance among cultivars in 2013, respectively, suggesting that cultivars influenced CS pathogen growth conditions. The results suggested that the genetic background of potato cultivars influenced the abundance of pathogenic Streptomyces spp., with 5 to 6 times more abundant Streptomyces spp. in RS of susceptible cultivars compared with tolerant cultivars, which would result in substantially more inoculum left in the field after harvest.  .

The Human Release Hypothesis for biological invasions: human activity as a determinant of the abundance of invasive plant species.

PubMed

Zimmermann, Heike; Brandt, Patric; Fischer, Joern; Welk, Erik; von Wehrden, Henrik

2014-01-01

Research on biological invasions has increased rapidly over the past 30 years, generating numerous explanations of how species become invasive. While the mechanisms of invasive species establishment are well studied, the mechanisms driving abundance patterns (i.e. patterns of population density and population size) remain poorly understood. It is assumed that invasive species typically have higher abundances in their new environments than in their native ranges, and patterns of invasive species abundance differ between invaded regions. To explain differences in invasive species abundance, we propose the Human Release Hypothesis. In parallel to the established Enemy Release Hypothesis, this hypothesis states that the differences in abundance of invasive species are found between regions because population expansion is reduced in some regions through continuous land management and associated cutting of the invasive species. The Human Release Hypothesis does not negate other important drivers of species invasions, but rather should be considered as a potentially important complementary mechanism. We illustrate the hypothesis via a case study on an invasive rose species, and hypothesize which locations globally may be most likely to support high abundances of invasive species. We propose that more extensive empirical work on the Human Release Hypothesis could be useful to test its general applicability.

The Human Release Hypothesis for biological invasions: human activity as a determinant of the abundance of invasive plant species

PubMed Central

Zimmermann, Heike; Brandt, Patric; Fischer, Joern; Welk, Erik; von Wehrden, Henrik

2014-01-01

Research on biological invasions has increased rapidly over the past 30 years, generating numerous explanations of how species become invasive. While the mechanisms of invasive species establishment are well studied, the mechanisms driving abundance patterns (i.e. patterns of population density and population size) remain poorly understood. It is assumed that invasive species typically have higher abundances in their new environments than in their native ranges, and patterns of invasive species abundance differ between invaded regions. To explain differences in invasive species abundance, we propose the Human Release Hypothesis. In parallel to the established Enemy Release Hypothesis, this hypothesis states that the differences in abundance of invasive species are found between regions because population expansion is reduced in some regions through continuous land management and associated cutting of the invasive species. The Human Release Hypothesis does not negate other important drivers of species invasions, but rather should be considered as a potentially important complementary mechanism. We illustrate the hypothesis via a case study on an invasive rose species, and hypothesize which locations globally may be most likely to support high abundances of invasive species. We propose that more extensive empirical work on the Human Release Hypothesis could be useful to test its general applicability. PMID:25352979

Factors contributing to variability in larval ingress of Atlantic menhaden, Brevoortia tyrannus

NASA Astrophysics Data System (ADS)

Lozano, C.; Houde, E. D.

2013-02-01

Annual recruitment levels of age-0 juvenile Atlantic menhaden to Chesapeake Bay, which historically supported >65% of coastwide recruitment, have been consistently low since the 1980s. Diminished larval supply to the Bay is one hypothesized explanation. In a three-year ichthyoplankton survey at the Chesapeake Bay mouth, abundance of ingressing larvae varied nine-fold among years. Larvae were most abundant in 2007-2008 and less abundant in 2005-2006 and 2006-2007. High month-to-month variability in larval concentrations was attributable primarily to seasonality of occurrences. There was no defined spatial pattern in distribution of larvae across the 18-km-wide Bay mouth, but larvae at the south side were longer and older on average than larvae at the middle and north side. Environmental variables measured at the times of larval collections were not correlated consistently with temporal and spatial variability in abundance of larvae at ingress, highlighting complexity and suggesting that abundance may be controlled by processes occurring offshore during the pre-ingress phase. Moreover, the substantial differences in inter-annual abundances of larvae at the Bay mouth were not concordant with subsequent abundances of age-0 juveniles in the three survey years, indicating that important processes affecting recruitment of Atlantic menhaden operate after ingress, during the larval to juvenile transition stage.

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.

CHROMOSPHERIC MODELS AND THE OXYGEN ABUNDANCE IN GIANT STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupree, A. K.; Avrett, E. H.; Kurucz, R. L., E-mail: dupree@cfa.harvard.edu

Realistic stellar atmospheric models of two typical metal-poor giant stars in Omega Centauri, which include a chromosphere (CHR), influence the formation of optical lines of O i: the forbidden lines (λ6300, λ6363) and the infrared triplet (λλ7771−7775). One-dimensional semi-empirical non-local thermodynamic equilibrium (LTE) models are constructed based on observed Balmer lines. A full non-LTE formulation is applied for evaluating the line strengths of O i, including photoionization by the Lyman continuum and photoexcitation by Lyα and Lyβ. Chromospheric models (CHR) yield forbidden oxygen transitions that are stronger than those in radiative/convective equilibrium (RCE) models. The triplet oxygen lines from highmore » levels also appear stronger than those produced in an RCE model. The inferred oxygen abundance from realistic CHR models for these two stars is decreased by factors of ∼3 as compared to values derived from RCE models. A lower oxygen abundance suggests that intermediate-mass AGB stars contribute to the observed abundance pattern in globular clusters. A change in the oxygen abundance of metal-poor field giants could affect models of deep mixing episodes on the red giant branch. Changes in the oxygen abundance can impact other abundance determinations that are critical to astrophysics, including chemical tagging techniques and galactic chemical evolution.« less

Abundances of Local Group Globular Clusters Using High Resolution Integrated Light Spectroscopy

NASA Astrophysics Data System (ADS)

Sakari, Charli; McWilliam, A.; Venn, K.; Shetrone, M. D.; Dotter, A. L.; Mackey, D.

2014-01-01

Abundances and kinematics of extragalactic globular clusters provide valuable clues about galaxy and globular cluster formation in a wide variety of environments. In order to obtain such information about distant, unresolved systems, specific observational techniques are required. An Integrated Light Spectrum (ILS) provides a single spectrum from an entire stellar population, and can therefore be used to determine integrated cluster abundances. This dissertation investigates the accuracy of high resolution ILS analysis methods, using ILS (taken with the Hobby-Eberly Telescope) of globular clusters associated with the Milky Way (47 Tuc, M3, M13, NGC 7006, and M15) and then applies the method to globular clusters in the outer halo of M31 (from the Pan-Andromeda Archaeological Survey, or PAndAS). Results show that: a) as expected, the high resolution method reproduces individual stellar abundances for elements that do not vary within a cluster; b) the presence of multiple populations does affect the abundances of elements that vary within the cluster; c) certain abundance ratios are very sensitive to systematic effects, while others are not; and d) certain abundance ratios (e.g. [Ca/Fe]) can be accurately obtained from unresolved systems. Applications of ILABUNDS to the PAndAS clusters reveal that accretion may have played an important role in the formation of M31's outer halo.

Modeling abundance effects in distance sampling

USGS Publications Warehouse

Royle, J. Andrew; Dawson, D.K.; Bates, S.

2004-01-01

Distance-sampling methods are commonly used in studies of animal populations to estimate population density. A common objective of such studies is to evaluate the relationship between abundance or density and covariates that describe animal habitat or other environmental influences. However, little attention has been focused on methods of modeling abundance covariate effects in conventional distance-sampling models. In this paper we propose a distance-sampling model that accommodates covariate effects on abundance. The model is based on specification of the distance-sampling likelihood at the level of the sample unit in terms of local abundance (for each sampling unit). This model is augmented with a Poisson regression model for local abundance that is parameterized in terms of available covariates. Maximum-likelihood estimation of detection and density parameters is based on the integrated likelihood, wherein local abundance is removed from the likelihood by integration. We provide an example using avian point-transect data of Ovenbirds (Seiurus aurocapillus) collected using a distance-sampling protocol and two measures of habitat structure (understory cover and basal area of overstory trees). The model yields a sensible description (positive effect of understory cover, negative effect on basal area) of the relationship between habitat and Ovenbird density that can be used to evaluate the effects of habitat management on Ovenbird populations.

How have fisheries affected parasite communities?

USGS Publications Warehouse

Wood, Chelsea L.; Lafferty, Kevin D.

2015-01-01

To understand how fisheries affect parasites, we conducted a meta-analysis of studies that contrasted parasite assemblages in fished and unfished areas. Parasite diversity was lower in hosts from fished areas. Larger hosts had a greater abundance of parasites, suggesting that fishing might reduce the abundance of parasites by selectively removing the largest, most heavily parasitized individuals. After controlling for size, the effect of fishing on parasite abundance varied according to whether the host was fished and the parasite's life cycle. Parasites of unfished hosts were more likely to increase in abundance in response to fishing than were parasites of fished hosts, possibly due to compensatory increases in the abundance of unfished hosts. While complex life cycle parasites tended to decline in abundance in response to fishing, directly transmitted parasites tended to increase. Among complex life cycle parasites, those with fished hosts tended to decline in abundance in response to fishing, while those with unfished hosts tended to increase. However, among directly transmitted parasites, responses did not differ between parasites with and without fished hosts. This work suggests that parasite assemblages are likely to change substantially in composition in increasingly fished ecosystems, and that parasite life history and fishing status of the host are important in predicting the response of individual parasite species or groups to fishing.

Quantifying the past and future impact of climate on outbreak patterns of bank voles (Myodes glareolus).

PubMed

Imholt, Christian; Reil, Daniela; Eccard, Jana A; Jacob, Daniela; Hempelmann, Nils; Jacob, Jens

2015-02-01

Central European outbreak populations of the bank vole (Myodes glareolus Schreber) are known to cause damage in forestry and to transmit the most common type of Hantavirus (Puumala virus, PUUV) to humans. A sound estimation of potential effects of future climate scenarios on population dynamics is a prerequisite for long-term management strategies. Historic abundance time series were used to identify the key weather conditions associated with bank vole abundance, and were extrapolated to future climate scenarios to derive potential long-term changes in bank vole abundance dynamics. Classification and regression tree analysis revealed the most relevant weather parameters associated with high and low bank vole abundances. Summer temperatures 2 years prior to trapping had the highest impact on abundance fluctuation. Extrapolation of the identified parameters to future climate conditions revealed an increase in years with high vole abundance. Key weather patterns associated with vole abundance reflect the importance of superabundant food supply through masting to the occurrence of bank vole outbreaks. Owing to changing climate, these outbreaks are predicted potentially to increase in frequency 3-4-fold by the end of this century. This may negatively affect damage patterns in forestry and the risk of human PUUV infection in the long term. © 2014 Society of Chemical Industry.

Critical evaluation of five methods for quantifying chewing lice (Insecta: Phthiraptera).

PubMed

Clayton, D H; Drown, D M

2001-12-01

Five methods for estimating the abundance of chewing lice (Insecta: Phthiraptera) were tested. To evaluate the methods, feral pigeons (Columba livia) and 2 species of ischnoceran lice were used. The fraction of lice removed by each method was compared, and least squares linear regression was used to determine how well each method predicted total abundance. Total abundance was assessed in most cases using KOH dissolution. The 2 methods involving dead birds (body washing and post-mortem-ruffling) provided better results than 3 methods involving live birds (dust-ruffling, fumigation chambers, and visual examination). Body washing removed the largest fraction of lice (>82%) and was an extremely accurate predictor of total abundance (r2 = 0.99). Post-mortem-ruffling was also an accurate predictor of total abundance (r2 > or = 0.88), even though it removed a smaller proportion of lice (<70%) than body washing. Dust-ruffling and fumigation chambers removed even fewer lice, but were still reasonably accurate predictors of total abundance, except in the case of data sets restricted to birds with relatively few lice. Visual examination, the only method not requiring that lice be removed from the host, was an accurate predictor of louse abundance, except in the case of wing lice on lightly parasitized birds.

Detecting declines in the abundance of a bull trout (Salvelinus confluentus) population: Understanding the accuracy, precision, and costs of our efforts

USGS Publications Warehouse

Al-Chokhachy, R.; Budy, P.; Conner, M.

2009-01-01

Using empirical field data for bull trout (Salvelinus confluentus), we evaluated the trade-off between power and sampling effort-cost using Monte Carlo simulations of commonly collected mark-recapture-resight and count data, and we estimated the power to detect changes in abundance across different time intervals. We also evaluated the effects of monitoring different components of a population and stratification methods on the precision of each method. Our results illustrate substantial variability in the relative precision, cost, and information gained from each approach. While grouping estimates by age or stage class substantially increased the precision of estimates, spatial stratification of sampling units resulted in limited increases in precision. Although mark-resight methods allowed for estimates of abundance versus indices of abundance, our results suggest snorkel surveys may be a more affordable monitoring approach across large spatial scales. Detecting a 25% decline in abundance after 5 years was not possible, regardless of technique (power = 0.80), without high sampling effort (48% of study site). Detecting a 25% decline was possible after 15 years, but still required high sampling efforts. Our results suggest detecting moderate changes in abundance of freshwater salmonids requires considerable resource and temporal commitments and highlight the difficulties of using abundance measures for monitoring bull trout populations.

Direct evidence that density-dependent regulation underpins the temporal stability of abundant species in a diverse animal community

PubMed Central

Henderson, Peter A.; Magurran, Anne E.

2014-01-01

To understand how ecosystems are structured and stabilized, and to identify when communities are at risk of damage or collapse, we need to know how the abundances of the taxa in the entire assemblage vary over ecologically meaningful timescales. Here, we present an analysis of species temporal variability within a single large vertebrate community. Using an exceptionally complete 33-year monthly time series following the dynamics of 81 species of fishes, we show that the most abundant species are least variable in terms of temporal biomass, because they are under density-dependent (negative feedback) regulation. At the other extreme, a relatively large number of low abundance transient species exhibit the greatest population variability. The high stability of the consistently common high abundance species—a result of density-dependence—is reflected in the observation that they consistently represent over 98% of total fish biomass. This leads to steady ecosystem nutrient and energy flux irrespective of the changes in species number and abundance among the large number of low abundance transient species. While the density-dependence of the core species ensures stability under the existing environmental regime, the pool of transient species may support long-term stability by replacing core species should environmental conditions change. PMID:25100702

Identification of Differentially Abundant Proteins of Edwardsiella ictaluri during Iron Restriction

PubMed Central

Dumpala, Pradeep R.; Peterson, Brian C.; Lawrence, Mark L.; Karsi, Attila

2015-01-01

Edwardsiella ictaluri is a Gram-negative facultative anaerobe intracellular bacterium that causes enteric septicemia in channel catfish. Iron is an essential inorganic nutrient of bacteria and is crucial for bacterial invasion. Reduced availability of iron by the host may cause significant stress for bacterial pathogens and is considered a signal that leads to significant alteration in virulence gene expression. However, the precise effect of iron-restriction on E. ictaluri protein abundance is unknown. The purpose of this study was to identify differentially abundant proteins of E. ictaluri during in vitro iron-restricted conditions. We applied two-dimensional difference in gel electrophoresis (2D-DIGE) for determining differentially abundant proteins and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF/TOF MS) for protein identification. Gene ontology and pathway-based functional modeling of differentially abundant proteins was also conducted. A total of 50 unique differentially abundant proteins at a minimum of 2-fold (p ≤ 0.05) difference in abundance due to iron-restriction were detected. The numbers of up- and down-regulated proteins were 37 and 13, respectively. We noted several proteins, including EsrB, LamB, MalM, MalE, FdaA, and TonB-dependent heme/hemoglobin receptor family proteins responded to iron restriction in E. ictaluri. PMID:26168192

Chemical composition of A and F dwarfs members of the Hyades open cluster

NASA Astrophysics Data System (ADS)

Gebran, M.; Vick, M.; Monier, R.; Fossati, L.

2010-11-01

Aims: Abundances of 15 chemical elements have been derived for 28 F and 16 A stars members of the Hyades open cluster in order to set constraints on self-consistent evolutionary models that include radiative and turbulent diffusion. Methods: A spectral synthesis, iterative procedure was applied to derive the abundances from selected high-quality lines in high-resolution, high-signal-to-noise spectra obtained with SOPHIE and AURELIE at the Observatoire de Haute Provence. Results: The abundance patterns found for A and F stars in the Hyades resemble those observed in Coma Berenices and Pleiades clusters. In graphs representing the abundances versus the effective temperature, A stars often display much more scattered abundances around their mean values than the coolest F stars do. Large star-to-star variations are detected in the Hyades A dwarfs in their abundances of C, Na, Sc, Fe, Ni, Sr, Y, and Zr, which we interpret as evidence of transport processes competing with radiative diffusion. In A and Am stars, the abundances of Cr, Ni, Sr, Y, and Zr are found to be correlated with that of Fe as in the Pleiades and in Coma Berenices. The ratios C/Fe and O/Fe are found to be anticorrelated with Fe/H as in Coma Berenices. All Am stars in the Hyades are deficient in C and O and overabundant in elements heavier than Fe but not all are deficient in Ca and/or Sc. The F stars have solar abundances for almost all elements except for Si. The overall shape of the abundance pattern of the slow rotator HD 30210 cannot be entirely reproduced by models including radiative diffusion and different amounts of turbulent diffusion. Conclusions: While part of the discrepancies between derived and predicted abundances could come from non-LTE effects, including competing processes such as rotational mixing and/or mass loss seems necessary in order to improve the agreement between the observed and predicted abundance patterns. Tables 5 to 8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/523/A71Based on observations at the Observatoire de Haute-Provence, France.

Long-term trends in submersed aquatic vegetation (SAV) in Chesapeake Bay, USA, related to water quality

USGS Publications Warehouse

Orth, Robert J.; Williams, Michael R.; Marion, Scott R.; Wilcox, David J.; Carruthers, Tim J.B.; Moore, Kenneth A.; Kemp, W.M.; Dennison, William C.; Rybicki, Nancy B.; Peter Bergstrom,; Batiuk, Richard A.

2010-01-01

Chesapeake Bay supports a diverse assemblage of marine and freshwater species of submersed aquatic vegetation (SAV) whose broad distributions are generally constrained by salinity. An annual aerial SAV monitoring program and a bi-monthly to monthly water quality monitoring program have been conducted throughout Chesapeake Bay since 1984. We performed an analysis of SAV abundance and up to 22 environmental variables potentially influencing SAV growth and abundance (1984-2006). Historically, SAV abundance has changed dramatically in Chesapeake Bay, and since 1984, when SAV abundance was at historic low levels, SAV has exhibited complex changes including long-term (decadal) increases and decreases, as well as some large, single-year changes. Chesapeake Bay SAV was grouped into three broad-scale community-types based on salinity regime, each with their own distinct group of species, and detailed analyses were conducted on these three community-types as well as on seven distinct case-study areas spanning the three salinity regimes. Different trends in SAVabundance were evident in the different salinity regimes. SAV abundance has (a) continually increased in the low-salinity region; (b) increased initially in the medium-salinity region, followed by fluctuating abundances; and (c) increased initially in the high-salinity region, followed by a subsequent decline. In all areas, consistent negative correlations between measures of SAV abundance and nitrogen loads or concentrations suggest that meadows are responsive to changes in inputs of nitrogen. For smaller case-study areas, different trends in SAV abundance were also noted including correlations to water clarity in high-salinity case-study areas, but nitrogen was highly correlated in all areas. Current maximum SAV coverage for almost all areas remain below restoration targets, indicating that SAV abundance and associated ecosystem services are currently limited by continued poor water quality, and specifically high nutrient concentrations, within Chesapeake Bay. The nutrient reductions noted in some tributaries, which were highly correlated to increases in SAV abundance, suggest management activities have already contributed to SAV increases in some areas, but the strong negative correlation throughout the Chesapeake Bay between nitrogen and SAV abundance also suggests that further nutrient reductions will be necessary for SAV to attain or exceed restoration targets throughout the bay.

Spectroscopic Analyses of Neutron Capture Elements in Open Clusters

NASA Astrophysics Data System (ADS)

O'Connell, Julia E.

The evolution of elements as a function or age throughout the Milky Way disk provides strong constraints for galaxy evolution models, and on star formation epochs. In an effort to provide such constraints, we conducted an investigation into r- and s-process elemental abundances for a large sample of open clusters as part of an optical follow-up to the SDSS-III/APOGEE-1 near infrared survey. To obtain data for neutron capture abundance analysis, we conducted a long-term observing campaign spanning three years (2013-2016) using the McDonald Observatory Otto Struve 2.1-meter telescope and Sandiford Cass Echelle Spectrograph (SES, R(lambda/Deltalambda) ˜60,000). The SES provides a wavelength range of ˜1400 A, making it uniquely suited to investigate a number of other important chemical abundances as well as the neutron capture elements. For this study, we derive abundances for 18 elements covering four nucleosynthetic families- light, iron-peak, neutron capture and alpha-elements- for ˜30 open clusters within 6 kpc of the Sun with ages ranging from ˜80 Myr to ˜10 Gyr. Both equivalent width (EW) measurements and spectral synthesis methods were employed to derive abundances for all elements. Initial estimates for model stellar atmospheres- effective temperature and surface gravity- were provided by the APOGEE data set, and then re-derived for our optical spectra by removing abundance trends as a function of excitation potential and reduced width log(EW/lambda). With the exception of Ba II and Zr I, abundance analyses for all neutron capture elements were performed by generating synthetic spectra from the new stellar parameters. In order to remove molecular contamination, or blending from nearby atomic features, the synthetic spectra were modeled by a best-fit Gaussian to the observed data. Nd II shows a slight enhancement in all cluster stars, while other neutron capture elements follow solar abundance trends. Ba II shows a large cluster-to-cluster abundance spread, consistent with other open cluster abundance studies. From log(Age) ˜8.5, this large spread as a function of age appears to replicate the findings from an earlier, much debated study by Orazi et al. (2009) which found a linear trend of decreasing barium abundance with increasing age.

Variation in local abundance and species richness of stream fishes in relation to dispersal barriers: Implications for management and conservation

USGS Publications Warehouse

Nislow, K.H.; Hudy, M.; Letcher, B.H.; Smith, E.P.

2011-01-01

1.Barriers to immigration, all else being equal, should in principle depress local abundance and reduce local species richness. These issues are particularly relevant to stream-dwelling species when improperly designed road crossings act as barriers to migration with potential impacts on the viability of upstream populations. However, because abundance and richness are highly spatially and temporally heterogeneous and the relative importance of immigration on demography is uncertain, population- and community-level effects can be difficult to detect. 2.In this study, we tested the effects of potential barriers to upstream movements on the local abundance and species richness of a diverse assemblage of resident stream fishes in the Monongahela National Forest, West Virginia, U.S.A. Fishes were sampled using simple standard techniques above- and below road crossings that were either likely or unlikely to be barriers to upstream fish movements (based on physical dimensions of the crossing). We predicted that abundance of resident fishes would be lower in the upstream sections of streams with predicted impassable barriers, that the strength of the effect would vary among species and that variable effects on abundance would translate into lower species richness. 3.Supporting these predictions, the statistical model that best accounted for variation in abundance and species richness included a significant interaction between location (upstream or downstream of crossing) and type (passable or impassable crossing). Stream sections located above predicated impassable culverts had fewer than half the number of species and less than half the total fish abundance, while stream sections above and below passable culverts had essentially equivalent richness and abundance. 4.Our results are consistent with the importance of immigration and population connectivity to local abundance and species richness of stream fishes. In turn, these results suggest that when measured at appropriate scales (multiple streams within catchments), with simple protocols amenable to use by management agencies, differences in local abundance and species richness may serve as indicators of the extent to which road crossings are barriers to fish movement and help determine whether road-crossing improvements have restored connectivity to stream fish populations and communities. Published 2011. This article is a US Government work and is in the public domain in the USA.

The CO2 Abundance in Comets C2012 K1 (PanSTARRS), C2012 K5 (LINEAR), and 290P Jager as Measured with Spitzer

NASA Technical Reports Server (NTRS)

McKay, Adam J.; Kelley, Michael S.P.; Cochran, Anita L.; Bodewits, Dennis; DiSanti, Michael A.; Dello Russo, Neil; Lisse, Carey M.

2015-01-01

Carbon dioxide is one of the most abundant ices present in comets and is therefore important for understanding cometary composition and activity. We present analysis of observations of CO2 and [O I] emission in three comets to measure the CO2 abundance and evaluate the possibility of employing observations of [O I] emission in comets as a proxy for CO2. We obtained NIR imaging sensitive to CO2 of comets C/2012 K1 (PanSTARRS), C/2012 K5 (LINEAR), and 290P/Jager with the IRAC instrument on Spitzer. We acquired observations of [O I] emission in these comets with the ARCES echelle spectrometer mounted on the 3.5-m telescope at Apache Point Observatory and observations of OH with the Swift observatory (PanSTARRS) and with Keck HIRES (Jager). The CO2/H2O ratios derived from the Spitzer images are 12.6 +/- 1.3% (PanSTARRS), 28.9 +/- 3.6% (LINEAR), and 31.3 +/- 4.2% (Jager). These abundances are derived under the assumption that contamination from CO emission is negligible. The CO2 abundance for PanSTARRS is close to the average abundance measured in comets at similar heliocentric distance to date, while the abundances measured for LINEAR and Jager are significantly larger than the average abundance. From the coma morphology observed in PanSTARRS and the assumed gas expansion velocity, we derive a rotation period for the nucleus of about 9.2 h. Comparison of H2O production rates derived from ARCES and Swift data, as well as other observations, suggest the possibility of sublimation from icy grains in the inner coma. We evaluate the possibility that the [O I] emission can be employed as a proxy for CO2 by comparing CO2/H2O ratios inferred from the [O I] lines to those measured directly by Spitzer. We find that for PanSTARRS we can reproduce the observed CO2 abundance to an accuracy of approximately 20%. For LINEAR and Jager, we were only able to obtain upper limits on the CO2 abundance inferred from the [O I] lines. These upper limits are consistent with the CO2 abundances measured by Spitzer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushchenko, Alexander V.; Kang, Young-Woon; Kim, Sungeun

We investigated the chemical composition of ρ Pup using high-resolution spectral observations taken from the Very Large Telescope and the IUE archives and also spectra obtained at the 1.8 m telescope of the Bohyunsan observatory in Korea. The abundances of 56 chemical elements and the upper limits of Li and Be abundances were determined. The abundance pattern of ρ Pup was found to be similar to that of Am-type stars. The possibility of the influence of the accretion of interstellar gas and dust on the abundance patterns of B–F-type stars is discussed. The plots of the relative abundances of chemicalmore » elements in the atmospheres of ρ Pup and δ Sct versus the second ionization potentials of these elements show the correlations. The discontinuities at 13.6 and 24.6 eV—the ionization potentials of hydrogen and helium, respectively, are also exhibited in these plots. These discontinuities can be explained by interaction of the atoms of interstellar gas, mainly hydrogen and helium atoms, with the atoms of stellar photospheres (so-called charge-exchange reactions). Note that only the jumps near 13.6 and 24.6 eV were pointed out in previous investigations of relative abundances versus the second ionization potentials for Am-type stars. The dependencies of the relative abundances of chemical elements on the second ionization potentials of these elements were investigated using the published abundance patterns of B–F-type stars. The correlations of relative and absolute abundances of chemical elements, second ionization potentials, and projected rotational velocities are clearly detected for stars with effective temperatures between 7,000 and 12,000 K. If the correlation of relative abundances and second ionization potentials can be explained by the accretion of interstellar gas on the stellar surfaces, the investigation of these correlations can provide valuable information on the density and velocities of interstellar gas in different regions of the Galaxy and also on the influence of this phenomenon on stellar evolution. The dependencies of the relative abundances of chemical elements on the condensation temperatures of these elements were also found in the atmospheres of ρ Pup, δ Sct, and other B–F-type stars. Ten possible λ Boo-type stars were detected. The effective temperatures of these objects are between 10,900 and 14,000 K.« less

Beryllium abundances along the evolutionary sequence of the open cluster IC 4651 - A new test for hydrodynamical stellar models

NASA Astrophysics Data System (ADS)

Smiljanic, R.; Pasquini, L.; Charbonnel, C.; Lagarde, N.

2010-02-01

Context. Previous analyses of lithium abundances in main sequence and red giant stars have revealed the action of mixing mechanisms other than convection in stellar interiors. Beryllium abundances in stars with Li abundance determinations can offer valuable complementary information on the nature of these mechanisms. Aims: Our aim is to derive Be abundances along the whole evolutionary sequence of an open cluster. We focus on the well-studied open cluster IC 4651. These Be abundances are used with previously determined Li abundances, in the same sample stars, to investigate the mixing mechanisms in a range of stellar masses and evolutionary stages. Methods: Atmospheric parameters were adopted from a previous abundance analysis by the same authors. New Be abundances have been determined from high-resolution, high signal-to-noise UVES spectra using spectrum synthesis and model atmospheres. The careful synthetic modeling of the Be lines region is used to calculate reliable abundances in rapidly rotating stars. The observed behavior of Be and Li is compared to theoretical predictions from stellar models including rotation-induced mixing, internal gravity waves, atomic diffusion, and thermohaline mixing. Results: Beryllium is detected in all the main sequence and turn-off sample stars, both slow- and fast-rotating stars, including the Li-dip stars, but is not detected in the red giants. Confirming previous results, we find that the Li dip is also a Be dip, although the depletion of Be is more modest than for Li in the corresponding effective temperature range. For post-main-sequence stars, the Be dilution starts earlier within the Hertzsprung gap than expected from classical predictions, as does the Li dilution. A clear dispersion in the Be abundances is also observed. Theoretical stellar models including the hydrodynamical transport processes mentioned above are able to reproduce all the observed features well. These results show a good theoretical understanding of the Li and Be behavior along the color-magnitude diagram of this intermediate-age cluster for stars more massive than 1.2 M⊙. Based on observations made with the ESO VLT, at Paranal Observatory, under programs 065.L-0427 and 067.D-0126.Current address: European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany.

Modeling Culex tarsalis abundance on the northern Colorado front range using a landscape-level approach.

PubMed

Schurich, Jessica A; Kumar, Sunil; Eisen, Lars; Moore, Chester G

2014-03-01

Remote sensing and Geographic Information System (GIS) data can be used to identify larval mosquito habitats and predict species distribution and abundance across a landscape. An understanding of the landscape features that impact abundance and dispersal can then be applied operationally in mosquito control efforts to reduce the transmission of mosquito-borne pathogens. In an effort to better understand the effects of landscape heterogeneity on the abundance of the West Nile virus (WNV) vector Culex tarsalis, we determined associations between GIS-based environmental data at multiple spatial extents and monthly abundance of adult Cx. tarsalis in Larimer County and Weld County, CO. Mosquito data were collected from Centers for Disease Control and Prevention miniature light traps operated as part of local WNV surveillance efforts. Multiple regression models were developed for prediction of monthly Cx. tarsalis abundance for June, July, and August using 4 years of data collected over 2007-10. The models explained monthly adult mosquito abundance with accuracies ranging from 51-61% in Fort Collins and 57-88% in Loveland-Johnstown. Models derived using landscape-level predictors indicated that adult Cx. tarsalis abundance is negatively correlated with elevation. In this case, low-elevation areas likely more abundantly include habitats for Cx. tarsalis. Model output indicated that the perimeter of larval sites is a significant predictor of Cx. tarsalis abundance at a spatial extent of 500 m in Loveland-Johnstown in all months examined. The contribution of irrigated crops at a spatial extent of 500 m improved model fit in August in both Fort Collins and Loveland-Johnstown. These results emphasize the significance of irrigation and the manual control of water across the landscape to provide viable larval habitats for Cx. tarsalis in the study area. Results from multiple regression models can be applied operationally to identify areas of larval Cx. tarsalis production (irrigated crops lands and standing water) and assign priority in larval treatments to areas with a high density of larval sites at relevant spatial extents around urban locations.

When winners become losers: Predicted nonlinear responses of arctic birds to increasing woody vegetation

USGS Publications Warehouse

Thompson, Sarah J.; Handel, Colleen M.; Richardson, Rachel M.; McNew, Lance B.

2016-01-01

Climate change is facilitating rapid changes in the composition and distribution of vegetation at northern latitudes, raising questions about the responses of wildlife that rely on arctic ecosystems. One widely observed change occurring in arctic tundra ecosystems is an increasing dominance of deciduous shrub vegetation. Our goals were to examine the tolerance of arctic-nesting bird species to existing gradients of vegetation along the boreal forest-tundra ecotone, to predict the abundance of species across different heights and densities of shrubs, and to identify species that will be most or least responsive to ongoing expansion of shrubs in tundra ecosystems. We conducted 1,208 point counts on 12 study blocks from 2012–2014 in northwestern Alaska, using repeated surveys to account for imperfect detection of birds. We considered the importance of shrub height, density of low and tall shrubs (i.e. shrubs >0.5 m tall), percent of ground cover attributed to shrubs (including dwarf shrubs <0.5 m tall), and percent of herbaceous plant cover in predicting bird abundance. Among 17 species considered, only gray-cheeked thrush (Catharus minimus) abundance was associated with the highest values of all shrub metrics in its top predictive model. All other species either declined in abundance in response to one or more shrub metrics or reached a threshold where further increases in shrubs did not contribute to greater abundance. In many instances the relationship between avian abundance and shrubs was nonlinear, with predicted abundance peaking at moderate values of the covariate, then declining at high values. In particular, a large number of species were responsive to increasing values of average shrub height with six species having highest abundance at near-zero values of shrub height and abundance of four other species decreasing once heights reached moderate values (≤ 33 cm). Our findings suggest that increases in shrub cover and density will negatively affect abundance of only a few bird species and may potentially be beneficial for many others. As shrub height increases further, however, a considerable number of tundra bird species will likely find habitat increasingly unsuitable.

When Winners Become Losers: Predicted Nonlinear Responses of Arctic Birds to Increasing Woody Vegetation

PubMed Central

Thompson, Sarah J.; Handel, Colleen M.; Richardson, Rachel M.; McNew, Lance B.

2016-01-01

Climate change is facilitating rapid changes in the composition and distribution of vegetation at northern latitudes, raising questions about the responses of wildlife that rely on arctic ecosystems. One widely observed change occurring in arctic tundra ecosystems is an increasing dominance of deciduous shrub vegetation. Our goals were to examine the tolerance of arctic-nesting bird species to existing gradients of vegetation along the boreal forest-tundra ecotone, to predict the abundance of species across different heights and densities of shrubs, and to identify species that will be most or least responsive to ongoing expansion of shrubs in tundra ecosystems. We conducted 1,208 point counts on 12 study blocks from 2012–2014 in northwestern Alaska, using repeated surveys to account for imperfect detection of birds. We considered the importance of shrub height, density of low and tall shrubs (i.e. shrubs >0.5 m tall), percent of ground cover attributed to shrubs (including dwarf shrubs <0.5 m tall), and percent of herbaceous plant cover in predicting bird abundance. Among 17 species considered, only gray-cheeked thrush (Catharus minimus) abundance was associated with the highest values of all shrub metrics in its top predictive model. All other species either declined in abundance in response to one or more shrub metrics or reached a threshold where further increases in shrubs did not contribute to greater abundance. In many instances the relationship between avian abundance and shrubs was nonlinear, with predicted abundance peaking at moderate values of the covariate, then declining at high values. In particular, a large number of species were responsive to increasing values of average shrub height with six species having highest abundance at near-zero values of shrub height and abundance of four other species decreasing once heights reached moderate values (≤ 33 cm). Our findings suggest that increases in shrub cover and density will negatively affect abundance of only a few bird species and may potentially be beneficial for many others. As shrub height increases further, however, a considerable number of tundra bird species will likely find habitat increasingly unsuitable. PMID:27851768

Rhenium-osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites

NASA Astrophysics Data System (ADS)

Riches, Amy J. V.; Day, James M. D.; Walker, Richard J.; Simonetti, Antonio; Liu, Yang; Neal, Clive R.; Taylor, Lawrence A.

2012-11-01

Coupled 187Os/188Os compositions and highly-siderophile-element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance data are reported for eight angrite achondrite meteorites that include quenched- and slowly-cooled textural types. These data are combined with new major- and trace-element concentrations determined for bulk-rock powder fractions and constituent mineral phases, to assess angrite petrogenesis. Angrite meteorites span a wide-range of HSE abundances from <0.005 ppb Os (e.g., Northwest Africa [NWA] 1296; Angra dos Reis) to >100 ppb Os (NWA 4931). Chondritic to supra-chondritic 187Os/188Os (0.1201-0.2127) measured for Angra dos Reis and quenched-angrites correspond to inter- and intra-sample heterogeneities in Re/Os and HSE abundances. Quenched-angrites have chondritic-relative rare-earth-element (REE) abundances at 10-15×CI-chondrite, and their Os-isotope and HSE abundance variations represent mixtures of pristine uncontaminated crustal materials that experienced addition (<0.8%) of exogenous chondritic materials during or after crystallization. Slowly-cooled angrites (NWA 4590 and NWA 4801) have fractionated REE-patterns, chondritic to sub-chondritic 187Os/188Os (0.1056-0.1195), as well as low-Re/Os (0.03-0.13), Pd/Os (0.071-0.946), and relatively low-Pt/Os (0.792-2.640). Sub-chondritic 187Os/188Os compositions in NWA 4590 and NWA 4801 are unusual amongst planetary basalts, and their HSE and REE characteristics may be linked to melting of mantle sources that witnessed prior basaltic melt depletion. Angrite HSE-Yb systematics suggest that the HSE behaved moderately-incompatibly during angrite magma crystallization, implying the presence of metal in the crystallizing assemblage. The new HSE abundance and 187Os/188Os compositions indicate that the silicate mantle of the angrite parent body(ies) (APB) had HSE abundances in chondritic-relative proportions but at variable abundances at the time of angrite crystallization. The HSE systematics of angrites are consistent with protracted post-core formation accretion of materials with chondritic-relative abundances of HSE to the APB, and these accreted materials were rapidly, yet inefficiently, mixed into angrite magma source regions early in Solar System history.

Predicting foundation bunchgrass species abundances: Model-assisted decision-making in protected-area sagebrush steppe

USGS Publications Warehouse

Rodhouse, Thomas J.; Irvine, Kathryn M.; Sheley, Roger L.; Smith, Brenda S.; Hoh, Shirley; Esposito, Daniel M.; Mata-Gonzalez, Ricardo

2014-01-01

Foundation species are structurally dominant members of ecological communities that can stabilize ecological processes and influence resilience to disturbance and resistance to invasion. Being common, they are often overlooked for conservation but are increasingly threatened from land use change, biological invasions, and over-exploitation. The pattern of foundation species abundances over space and time may be used to guide decision-making, particularly in protected areas for which they are iconic. We used ordinal logistic regression to identify the important environmental influences on the abundance patterns of bluebunch wheatgrass (Pseudoroegneria spicata), Thurber's needlegrass (Achnatherum thurberianum), and Sandberg bluegrass (Poa secunda) in protected-area sagebrush steppe. We then predicted bunchgrass abundances along gradients of topography, disturbance, and invasive annual grass abundance. We used model predictions to prioritize the landscape for implementation of a management and restoration decision-support tool. Models were fit to categorical estimates of grass cover obtained from an extensive ground-based monitoring dataset. We found that remnant stands of abundant wheatgrass and bluegrass were associated with steep north-facing slopes in higher and more remote portions of the landscape outside of recently burned areas where invasive annual grasses were less abundant. These areas represented only 25% of the landscape and were prioritized for protection efforts. Needlegrass was associated with south-facing slopes, but in low abundance and in association with invasive cheatgrass (Bromus tectorum). Abundances of all three species were strongly negatively correlated with occurrence of another invasive annual grass, medusahead (Taeniatherum caput-medusae). The rarity of priority bunchgrass stands underscored the extent of degradation and the need for prioritization. We found no evidence that insularity reduced invasibility; annual grass invasion represents a serious threat to protected-area bunchgrass communities. Our study area was entirely within the Wyoming big sagebrush ecological zone, understood to have inherently low resilience to disturbance and resistance to weed invasion. However, our study revealed important variation in abundance of the foundation species associated with resilience and resistance along the topographic-soil moisture gradient within this zone, providing an important foothold for conservation decision-making in these steppe ecosystems. We found the foundation species focus a parsimonious strategy linking monitoring to decision-making via biogeographic modeling.

Urbanized landscapes favored by fig-eating birds increase invasive but not native juvenile strangler fig abundance.

PubMed

Caughlin, Trevor; Wheeler, Jessica H; Jankowski, Jill; Lichstein, Jeremy W

2012-07-01

Propagule pressure can determine the success or failure of invasive plant range expansion. Range expansion takes place at large spatial scales, often encompassing many types of land cover, yet the effect of landscape context on propagule pressure remains largely unknown. Many studies have reported a positive correlation between invasive plant abundance and human land use; increased propagule pressure in these landscapes may be responsible for this correlation. We tested the hypothesis that increased rates of seed dispersal by fig-eating birds, which are more common in urban habitats, result in an increase in invasive strangler fig abundance in landscapes dominated by human land use. We quantified abundance of an invasive species (Ficus microcarpa) and a native species (F. aurea) of strangler fig in plots spanning the entire range of human land use in South Florida, USA, from urban parking lots to native forest. We then compared models that predicted juvenile fig abundance based on distance to adult fig seed sources and fig-eating bird habitat quality with models that lacked one or both of these terms. The best model for juvenile invasive fig abundance included both distance to adult and fig-eating bird habitat terms, suggesting that landscape effects on invasive fig abundance are mediated by seed-dispersing birds. In contrast, the best model for juvenile native fig abundance included only presence/absence of adults, suggesting that distance from individual adult trees may have less effect on seed limitation for a native species compared to an invasive species undergoing range expansion. However, models for both species included significant effects of adult seed sources, implying that juvenile abundance is limited by seed arrival. This result was corroborated by a seed addition experiment that indicated that both native and invasive strangler figs were strongly seed limited. Understanding how landscape context affects the mechanisms of plant invasion may lead to better management techniques. Our results suggest that prioritizing removal of adult trees in sites with high fig-eating bird habitat may be the most effective method to control F. microcarpa abundance.

Distribution of invasive and native riparian woody plants across the western USA in relation to climate, river flow, floodplain geometry and patterns of introduction

USGS Publications Warehouse

Ryan McShane,; Daniel Auerbach,; Friedman, Jonathan M.; Auble, Gregor T.; Shafroth, Patrick B.; Michael Merigliano,; Scott, Michael L.; N. Leroy Poff,

2015-01-01

Management of riparian plant invasions across the landscape requires understanding the combined influence of climate, hydrology, geologic constraints and patterns of introduction. We measured abundance of nine riparian woody taxa at 456 stream gages across the western USA. We constructed conditional inference recursive binary partitioning models to discriminate the influence of eleven environmental variables on plant occurrence and abundance, focusing on the two most abundant non-native taxa, Tamarix spp. and Elaeagnus angustifolia, and their native competitor Populus deltoides. River reaches in this study were distributed along a composite gradient from cooler, wetter higher-elevation reaches with higher stream power and earlier snowmelt flood peaks to warmer, drier lower-elevation reaches with lower power and later peaks. Plant distributions were strongly related to climate, hydrologic and geomorphic factors, and introduction history. The strongest associations were with temperature and then precipitation. Among hydrologic and geomorphic variables, stream power, peak flow timing and 10-yr flood magnitude had stronger associations than did peak flow predictability, low-flow magnitude, mean annual flow and channel confinement. Nearby intentional planting of Elaeagnus was the best predictor of its occurrence, but planting of Tamarix was rare. Higher temperatures were associated with greater abundance of Tamarix relative to P. deltoides, and greater abundance of P. deltoides relative toElaeagnus. Populus deltoides abundance was more strongly related to peak flow timing than was that of Elaeagnus or Tamarix. Higher stream power and larger 10-yr floods were associated with greater abundance of P. deltoides and Tamarix relative to Elaeagnus. Therefore, increases in temperature could increase abundance of Tamarix and decrease that of Elaeagnus relative to P. deltoides, changes in peak flow timing caused by climate change or dam operations could increase abundance of both invasive taxa, and dam-induced reductions in flood peaks could increase abundance of Elaeagnus relative to Tamarix and P. deltoides.

From pest data to abundance-based risk maps combining eco-physiological knowledge, weather, and habitat variability.

PubMed

Lacasella, Federica; Marta, Silvio; Singh, Aditya; Stack Whitney, Kaitlin; Hamilton, Krista; Townsend, Phil; Kucharik, Christopher J; Meehan, Timothy D; Gratton, Claudio

2017-03-01

Noxious species, i.e., crop pest or invasive alien species, are major threats to both natural and managed ecosystems. Invasive pests are of special importance, and knowledge about their distribution and abundance is fundamental to minimize economic losses and prioritize management activities. Occurrence models are a common tool used to identify suitable zones and map priority areas (i.e., risk maps) for noxious species management, although they provide a simplified description of species dynamics (i.e., no indication on species density). An alternative is to use abundance models, but translating abundance data into risk maps is often challenging. Here, we describe a general framework for generating abundance-based risk maps using multi-year pest data. We used an extensive data set of 3968 records collected between 2003 and 2013 in Wisconsin during annual surveys of soybean aphid (SBA), an exotic invasive pest in this region. By using an integrative approach, we modelled SBA responses to weather, seasonal, and habitat variability using generalized additive models (GAMs). Our models showed good to excellent performance in predicting SBA occurrence and abundance (TSS = 0.70, AUC = 0.92; R 2  = 0.63). We found that temperature, precipitation, and growing degree days were the main drivers of SBA trends. In addition, a significant positive relationship between SBA abundance and the availability of overwintering habitats was observed. Our models showed aphid populations were also sensitive to thresholds associated with high and low temperatures, likely related to physiological tolerances of the insects. Finally, the resulting aphid predictions were integrated using a spatial prioritization algorithm ("Zonation") to produce an abundance-based risk map for the state of Wisconsin that emphasized the spatiotemporal consistency and magnitude of past infestation patterns. This abundance-based risk map can provide information on potential foci of pest outbreaks where scouting efforts and prophylactic measures should be concentrated. The approach we took is general, relatively simple, and can be applied to other species, habitats and geographical areas for which species abundance data and biotic and abiotic data are available. © 2016 by the Ecological Society of America.

Effects of long-term elevated CO2, warming, and prolonged drought on Pleurozium-associated diazotrophic activity and abundance

NASA Astrophysics Data System (ADS)

Dyrnum, Kristine; Priemé, Anders; Michelsen, Anders

2014-05-01

Nitrogen (N2) fixation is the primary natural influx of N to terrestrial ecosystems, and changes in N2 fixation may have consequences for primary productivity and thus ecosystem function. We studied the activity and abundance of diazotrophs associated with the feather moss Pleurozium schreberi in a temperate heathland, after seven years of global change manipulations, including elevated atmospheric CO2 (510 ppm), increased temperature (0.5-1.5 ° C), and prolonged pre-summer droughts (4-6 weeks /year). Acetylene reduction assay was carried out monthly to monitor N2 fixation rates throughout one year, while nif H copy abundance, serving as a diazotroph abundance estimate, was measured by quantitative polymerase chain reaction (q-PCR). Prolonged summer droughts significantly increased both N2 fixation and nif H copy abundance, contrasting previous studies that demonstrate a direct negative correlation between N2 fixation and water availability. A shift in the relative abundance of N2-fixing bacteria from the green, upper parts of the moss stem to the lower, brown parts was observed. This shift could make diazotrophs less sensitive to desiccation, enabling N2 fixation to be upheld for longer during drought and thus causing higher abundance. Increased temperature likewise had a positive effect on the diazotroph abundance, although this did not translate into increased activity. Possibly, warming protects diazotrophs during extreme cold events, while actual N2 fixation is limited by water, disregarding a rise in potential N2 fixation caused by higher abundance. Increased CO2 caused no significant diazotroph response. Our study showed that long-term increase in temperature and recurrent drought events cause higher diazotroph abundance in Pleurozium schreberi and thus enhance the potential N2 fixations rate. Furthermore, our results indicate that diazotrophs may alter colonization patterns and thereby actively remain in the moss fraction less likely affected by desiccation. In consequence, Pleurozium-associated N2 fixation may become an even more important contributor of N for terrestrial ecosystems in a predicted future climate.

Predictive modelling of habitat selection by marine predators with respect to the abundance and depth distribution of pelagic prey.

PubMed

Boyd, Charlotte; Castillo, Ramiro; Hunt, George L; Punt, André E; VanBlaricom, Glenn R; Weimerskirch, Henri; Bertrand, Sophie

2015-11-01

Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey. We analysed contemporaneous data on the diving locations of two seabird species, the shallow-diving Peruvian Booby (Sula variegata) and deeper diving Guanay Cormorant (Phalacrocorax bougainvilliorum), and the abundance and depth distribution of their main prey, Peruvian anchoveta (Engraulis ringens). Based on this unique data set, we developed resource selection functions to test the hypothesis that the probability of seabird diving behaviour at a given location is a function of the relative abundance of prey in the upper water column. For both species, we show that the probability of diving behaviour is mostly explained by the distribution of prey at shallow depths. While the probability of diving behaviour increases sharply with prey abundance at relatively low levels of abundance, support for including abundance in addition to the depth distribution of prey is weak, suggesting that prey abundance was not a major factor determining the location of diving behaviour during the study period. The study thus highlights the importance of the depth distribution of prey for two species of seabird with different diving capabilities. The results complement previous research that points towards the importance of oceanographic processes that enhance the accessibility of prey to seabirds. The implications are that locations where prey is predictably found at accessible depths may be more important for surface foragers, such as seabirds, than locations where prey is predictably abundant. Analysis of the relative importance of abundance and accessibility is essential for the design and evaluation of effective management responses to reduced prey availability for seabirds and other top predators in marine systems. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

NEON AND OXYGEN ABUNDANCES AND ABUNDANCE RATIO IN THE SOLAR CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landi, E.; Testa, P., E-mail: elandi@umich.edu

2015-02-20

In this work we determine the Ne/O abundance ratio from Solar and Heliospheric Observatory (SOHO)/Solar Ultraviolet Measurement of Emitted Radiation (SUMER) off-disk observations of quiescent streamers over the 1996-2008 period. We find that the Ne/O ratio is approximately constant over solar cycle 23 from 1996 to 2005, at a value of 0.099 ± 0.017; this value is lower than the transition region determinations from the quiet Sun used to infer the neon photospheric abundance from the oxygen photospheric abundance. Also, the Ne/O ratio we determined from SUMER is in excellent agreement with in situ determinations from ACE/SWICS. In 2005-2008, the Ne/O abundancemore » ratio increased with time and reached 0.25 ± 0.05, following the same trend found in the slowest wind analyzed by ACE/SWICS. Further, we measure the absolute abundance in the corona for both oxygen and neon from the data set of 1996 November 22, obtaining A {sub o} = 8.99 ± 0.04 and A {sub Ne} = 7.92 ± 0.03, and we find that both elements are affected by the first ionization potential (FIP) effect, with oxygen being enhanced by a factor of 1.4-2.1 over its photospheric abundance, and neon being changed by a factor of 0.75-1.20. We conclude that the Ne/O ratio is not constant in the solar atmosphere, both in time and at different heights, and that it cannot be reliably used to infer the neon abundance in the photosphere. Also, we argue that the FIP effect was less effective during the minimum of solar cycle 24, and that the Ne/O = 0.25 ± 0.05 value measured at that time is closer to the true photospheric value, leading to a neon photospheric abundance larger than assumed by ≈40%. We discuss the implications of these results for the solar abundance problem, for the FIP effect, and for the identification of the source regions of the solar wind.« less

Does interference competition with wolves limit the distribution and abundance of coyotes?

PubMed

Berger, Kim Murray; Gese, Eric M

2007-11-01

Interference competition with wolves Canis lupus is hypothesized to limit the distribution and abundance of coyotes Canis latrans, and the extirpation of wolves is often invoked to explain the expansion in coyote range throughout much of North America. We used spatial, seasonal and temporal heterogeneity in wolf distribution and abundance to test the hypothesis that interference competition with wolves limits the distribution and abundance of coyotes. From August 2001 to August 2004, we gathered data on cause-specific mortality and survival rates of coyotes captured at wolf-free and wolf-abundant sites in Grand Teton National Park (GTNP), Wyoming, USA, to determine whether mortality due to wolves is sufficient to reduce coyote densities. We examined whether spatial segregation limits the local distribution of coyotes by evaluating home-range overlap between resident coyotes and wolves, and by contrasting dispersal rates of transient coyotes captured in wolf-free and wolf-abundant areas. Finally, we analysed data on population densities of both species at three study areas across the Greater Yellowstone Ecosystem (GYE) to determine whether an inverse relationship exists between coyote and wolf densities. Although coyotes were the numerically dominant predator, across the GYE, densities varied spatially and temporally in accordance with wolf abundance. Mean coyote densities were 33% lower at wolf-abundant sites in GTNP, and densities declined 39% in Yellowstone National Park following wolf reintroduction. A strong negative relationship between coyote and wolf densities (beta = -3.988, P < 0.005, r(2) = 0.54, n = 16), both within and across study sites, supports the hypothesis that competition with wolves limits coyote populations. Overall mortality of coyotes resulting from wolf predation was low, but wolves were responsible for 56% of transient coyote deaths (n = 5). In addition, dispersal rates of transient coyotes captured at wolf-abundant sites were 117% higher than for transients captured in wolf-free areas. Our results support the hypothesis that coyote abundance is limited by competition with wolves, and suggest that differential effects on survival and dispersal rates of transient coyotes are important mechanisms by which wolves reduce coyote densities.

Spectrometeric measurements of vertical profile and column abundance of NO2 at Zvenigorod, Russia: Fourteen years of observations

NASA Astrophysics Data System (ADS)

Gruzdev, A.; Elokhov, A.

Since 1990, NO2 measurements are carried out at Zvenigorod Research Station (56°N, 37°E), Moscow region, with the help of zenith viewing spectrophotometer in spectral range 435-450 nm. The instrument and method of observations were verified in comparison campaigns within the framework of the Network for Detection of Stratospheric Change. Measurements are done during morning and evening twilight at solar zenith angles 84-96°. Slant column NO2 abundances are derived from observed spectra taking into account O3 and NO2 absorption, single molecular and aerosol scattering, and the Ring effect. The NO2 abundances in the vertical column as well as vertical NO2 profiles are derived as solution of inverse mathematical problem (with Chahine method) using a spherical single scattering model and a one-dimensional photochemical model. Derived quantities are (1) NO2 abundances within 5-km thick layers in the stratosphere and troposphere, (2) NO2 abundance in the thin atmospheric near-surface layer and (3) columnar NO2 abundances in the troposphere (0-10 km) and the stratosphere (10-50 km) as integrals over appropriate layers. Results of measurements show variability of stratospheric and tropospheric NO2 at different time scales from the diurnal to the interannual scale. Out of the period affected by the Pinatubo eruption (1992-1994), a general decline of the stratospheric column NO2 abundance is occurring, superimposed by interannual variations. A linear, statistically significant, negative annual trend of about 12% per decade has been detected for both morning and evening stratospheric column NO2 abundances. For interpretation of the observed trend, a simple photochemical model is used, which takes into account the observed changes in N2O and stratospheric ozone abundances, and in temperature. The estimated model trend of the stratospheric column NO2 abundance in the extratropical Northern Hemisphere is about -5% per decade, which is less than observed. Dynamical variability is supposed to be responsible, in particular, for the observed NO2 decline.

Species composition, abundance, and seasonal dynamics of stink bugs (Hemiptera: Pentatomidae) in Minnesota soybean fields.

PubMed

Koch, Robert L; Pahs, Tiffany

2014-08-01

Stink bugs (Hemiptera: Pentatomidae) have historically not been pests of soybean in Minnesota. In response to the invasion of Halyomorpha halys (Stål) and reports of increasing abundance of species native to North America, a state-wide survey of soybean was conducted over 3 yr in Minnesota to determine species composition, abundance, and seasonal dynamics of Pentatomidae associated with soybean. Fourteen species of Pentatomidae (12 herbivorous and two predatory) were collected from soybean. H. halys was not detected in this survey. Among the herbivorous species found, adults of Euschistus variolarius (Palisot de Beauvois) had the greatest relative abundance (60.51%) and frequency of detection (18.44%), followed by Euschistus servus euschistoides (Say) (19.37 and 3.04%, respectively) and Chinavia hilaris (Say) (5.50 and 1.69%, respectively). Abundance of herbivorous nymphs and adults exceeded an economic threshold (20 nymphs and adults per 100 sweeps) in 0.82% of fields in 2012 but not in 2011 or 2013. The frequency of detection of herbivorous species and ratio of nymphs to adults increased with increasing reproductive growth stage of soybean. In two of three years, herbivorous adults were more abundant in the edge compared with interior of fields. Two predatory Pentatomidae, Podisus maculiventris (Say) and Podisus placidus Uhler, comprised 5.95 and 1.62% of the pentatomid adults. Though the species composition of Pentatomidae in Minnesota soybean differs from that in eastern and southern states, the spatial (i.e., greater abundance near field edge) and seasonal dynamics (i.e., increasing abundance and reproduction with increasing reproductive maturity of soybean) in soybean appear similar.

Responses of infaunal populations to benthoscape structure and the potential importance of transition zones

USGS Publications Warehouse

Zajac, R.N.; Lewis, R.S.; Poppe, L.J.; Twichell, D.C.; Vozarik, J.; DiGiacomo-Cohen, M. L.

2003-01-01

Relationships between population abundance and seafloor landscape, or benthoscape, structure were examined for 16 infaunal taxa in eastern Long Island Sound. Based on analyses of a side-scan sonar mosaic, the 19.4-km2 study area was comprised of six distinct large-scale (> km2) benthoscape elements, with varying levels of mesoscale (km2-m2) and small-scale (2) physical and biological habitat heterogeneity. Transition zones among elements varied from ~50 to 200 m in width, comprised ~32% of the benthoscape, and added to overall benthoscape heterogeneity. Population abundances of nine taxa varied significantly among the large-scale elements. Most species were found at high abundances only in one benthoscape element, but three had several foci of elevated abundances. Analyses of population responses to habitat heterogeneity at different spatial scales indicated that abundances of eight taxa varied significantly among spatial scales, but the significant scales were mixed among these species. Relatively large residual variations suggest significant amounts of mesoscale spatial variation were unaccounted for, varying from ~1 km2 to several m2. Responses to transition zones were mixed as well. Abundances of nine taxa varied significantly among transition zones and interiors of benthoscape elements, most with elevated abundances in transition zones. Our results show that infaunal populations exhibit complex and spatially varying patterns of abundance in relation to benthoscape structure and suggest that mesoscale variation may be particularly critical in this regard. Also, transition zones among benthoscape features add considerably to this variation and may be ecological important areas in seafloor environments.

Predicting recovery criteria for threatened and endangered plant species on the basis of past abundances and biological traits.

PubMed

Neel, Maile C; Che-Castaldo, Judy P

2013-04-01

Recovery plans for species listed under the U.S. Endangered Species Act are required to specify measurable criteria that can be used to determine when the species can be delisted. For the 642 listed endangered and threatened plant species that have recovery plans, we applied recursive partitioning methods to test whether the number of individuals or populations required for delisting can be predicted on the basis of distributional and biological traits, previous abundance at multiple time steps, or a combination of traits and previous abundances. We also tested listing status (threatened or endangered) and the year the recovery plan was written as predictors of recovery criteria. We analyzed separately recovery criteria that were stated as number of populations and as number of individuals (population-based and individual-based criteria, respectively). Previous abundances alone were relatively good predictors of population-based recovery criteria. Fewer populations, but a greater proportion of historically known populations, were required to delist species that had few populations at listing compared with species that had more populations at listing. Previous abundances were also good predictors of individual-based delisting criteria when models included both abundances and traits. The physiographic division in which the species occur was also a good predictor of individual-based criteria. Our results suggest managers are relying on previous abundances and patterns of decline as guidelines for setting recovery criteria. This may be justifiable in that previous abundances inform managers of the effects of both intrinsic traits and extrinsic threats that interact and determine extinction risk. © 2013 Society for Conservation Biology.

Using of ants and earthworm to modify of soil biological quality and its effect on cocoa seedlings growth

NASA Astrophysics Data System (ADS)

Kilowasid, Laode Muhammad Harjoni; Budianto, Wayan; Syaf, Hasbullah; Tufaila, Muhammad; Safuan, La Ode

2015-09-01

Ant and earthworm can act as soil ecosystem engineers. Ant and earthworm are very dominant in smallholder cocoa plantation. The first experiment aimed to study the effect of the abundance of ants and earthworms on soil microbial activity and microfauna, and the second experiment to analyse the effect of soil modified by ants and earthworms on the cocoa seedlings growth. Ant (Ponera sp.) and earthworm (Pontoscolex sp.) collected from smallholder cocoa plantation, and kept in a container up to applied. In the first experiment, nine combinations of the abundance of ants and earthworms applied to each pot containing 3 kg of soil from smallholder cocoa plantation, and each combination of the abundance was repeated five times in a completely randomized design. After the soil was incubated for thirty days, ants and earthworms removed from the soil using hand sorting techniques. Soil from each pot was analysed for soil microbial activity, abundance of flagellates and nematodes. In the second experiment, the soil in each pot was planted with cocoa seedlings and maintained up to ninety days. The results showed the FDA hydrolytic activity of microbes, the abundance of flagellates and nematodes between the combination of the abundance of ants and earthworms have been significantly different. Dry weight of root, shoot and seedling cacao have been significantly different between the combination of the abundance of ants and earthworms. It was concluded that the combination of the abundance of ants and earthworms can be used in ecological engineering to improve soil quality.

Differential application of lambda-cyhalothrin to control the sandfly Lutzomyia longipalpis.

PubMed

Kelly, D W; Mustafa, Z; Dye, C

1997-01-01

To study the impact of residual pyrethroid insecticide on the abundance and distribution of peridomestic Lutzomyia longipalpis, the sandfly vector of visceral leishmaniasis in Brazil, lambda-cyhalothrin was applied at 20 mg a.i.m-2 in the following interventions: (i) spraying of all animal pens in a village (blanket coverage); (ii) treatment of a subset of animal pens, either by spraying, or by installation of insecticide-impregnated 1 m2 cotton sheets as 'targets' (focal coverage). By sampling with CDC light traps, and using a novel analytical approach, we detected a 90% reduction in Lu.longipalpis abundance in sprayed sheds of the focal intervention. However, there was no discernible effect on the abundance of other phlebotomines trapped in sheds, or on the abundance of Lu.longipalpis in untreated dining-huts and houses. This differential impact on Lu.longipalpis abundance is explained in terms of the disruption of male pheromone production. Treated targets were approximately half as effective as residual spraying in reducing the abundance of Lu.longipalpis in sheds. Following blanket intervention, the abundance of Lu.longipalpis in traps fell by only 45% (not significant): catches at untreated dining-huts actually increased, possibly because the blanket coverage diverted Lu.longipalpis away from major aggregation sites at animal pens. It is recommended that care be taken during vector control programmes to ensure that all potential aggregation sites are treated. The possible consequences of leaving some sites untreated include poor control of peridomestic sandfly abundance and an increase in the biting rate on dogs and humans.

Re-constructing historical Adélie penguin abundance estimates by retrospectively accounting for detection bias.

PubMed

Southwell, Colin; Emmerson, Louise; Newbery, Kym; McKinlay, John; Kerry, Knowles; Woehler, Eric; Ensor, Paul

2015-01-01

Seabirds and other land-breeding marine predators are considered to be useful and practical indicators of the state of marine ecosystems because of their dependence on marine prey and the accessibility of their populations at breeding colonies. Historical counts of breeding populations of these higher-order marine predators are one of few data sources available for inferring past change in marine ecosystems. However, historical abundance estimates derived from these population counts may be subject to unrecognised bias and uncertainty because of variable attendance of birds at breeding colonies and variable timing of past population surveys. We retrospectively accounted for detection bias in historical abundance estimates of the colonial, land-breeding Adélie penguin through an analysis of 222 historical abundance estimates from 81 breeding sites in east Antarctica. The published abundance estimates were de-constructed to retrieve the raw count data and then re-constructed by applying contemporary adjustment factors obtained from remotely operating time-lapse cameras. The re-construction process incorporated spatial and temporal variation in phenology and attendance by using data from cameras deployed at multiple sites over multiple years and propagating this uncertainty through to the final revised abundance estimates. Our re-constructed abundance estimates were consistently higher and more uncertain than published estimates. The re-constructed estimates alter the conclusions reached for some sites in east Antarctica in recent assessments of long-term Adélie penguin population change. Our approach is applicable to abundance data for a wide range of colonial, land-breeding marine species including other penguin species, flying seabirds and marine mammals.

Establishing Ion Ratio Thresholds Based on Absolute Peak Area for Absolute Protein Quantification using Protein Cleavage Isotope Dilution Mass Spectrometry

PubMed Central

Loziuk, Philip L.; Sederoff, Ronald R.; Chiang, Vincent L.; Muddiman, David C.

2014-01-01

Quantitative mass spectrometry has become central to the field of proteomics and metabolomics. Selected reaction monitoring is a widely used method for the absolute quantification of proteins and metabolites. This method renders high specificity using several product ions measured simultaneously. With growing interest in quantification of molecular species in complex biological samples, confident identification and quantitation has been of particular concern. A method to confirm purity or contamination of product ion spectra has become necessary for achieving accurate and precise quantification. Ion abundance ratio assessments were introduced to alleviate some of these issues. Ion abundance ratios are based on the consistent relative abundance (RA) of specific product ions with respect to the total abundance of all product ions. To date, no standardized method of implementing ion abundance ratios has been established. Thresholds by which product ion contamination is confirmed vary widely and are often arbitrary. This study sought to establish criteria by which the relative abundance of product ions can be evaluated in an absolute quantification experiment. These findings suggest that evaluation of the absolute ion abundance for any given transition is necessary in order to effectively implement RA thresholds. Overall, the variation of the RA value was observed to be relatively constant beyond an absolute threshold ion abundance. Finally, these RA values were observed to fluctuate significantly over a 3 year period, suggesting that these values should be assessed as close as possible to the time at which data is collected for quantification. PMID:25154770

Host-Plant Specialization Mediates the Influence of Plant Abundance on Host Use by Flower Head-Feeding Insects.

PubMed

Nobre, Paola A F; Bergamini, Leonardo L; Lewinsohn, Thomas M; Jorge, Leonardo R; Almeida-Neto, Mário

2016-02-01

Among-population variation in host use is a common phenomenon in herbivorous insects. The simplest and most trivial explanation for such variation in host use is the among-site variation in plant species composition. Another aspect that can influence spatial variation in host use is the relative abundance of each host-plant species compared to all available hosts. Here, we used endophagous insects that develop in flower heads of Asteraceae species as a study system to investigate how plant abundance influences the pattern of host-plant use by herbivorous insects with distinct levels of host-range specialization. Only herbivores recorded on three or more host species were included in this study. In particular, we tested two related hypotheses: 1) plant abundance has a positive effect on the host-plant preference of herbivorous insects, and 2) the relative importance of plant abundance to host-plant preference is greater for herbivorous species that use a wider range of host-plant species. We analyzed 11 herbivore species in 20 remnants of Cerrado in Southeastern Brazil. For 8 out of 11 herbivore species, plant abundance had a positive influence on host use. In contrast to our expectation, both the most specialized and the most generalist herbivores showed a stronger positive effect of plant species abundance in host use. Thus, we found evidence that although the abundance of plant species is a major factor determining the preferential use of host plants, its relative importance is mediated by the host-range specialization of herbivores.

The impacts of land use change on malaria vector abundance in a water-limited, highland region of Ethiopia.

PubMed

Stryker, Jody J; Bomblies, Arne

2012-12-01

Changes in land use and climate are expected to alter the risk of malaria transmission in areas where rainfall limits vector abundance. We use a coupled hydrology-entomology model to investigate the effects of land use change on hydrological processes impacting mosquito abundance in a highland village of Ethiopia. Land use affects partitioning of rainfall into infiltration and runoff that reaches small-scale topographic depressions, which constitute the primary breeding habitat of Anopheles arabiensis mosquitoes. A physically based hydrology model isolates hydrological mechanisms by which land use impacts pool formation and persistence, and an agent-based entomology model evaluates the response of mosquito populations. This approach reproduced observed interannual variability in mosquito abundance between the 2009 and 2010 wet seasons. Several scenarios of land cover were then evaluated using the calibrated, field-validated model. Model results show variation in pool persistence and depth, as well as in mosquito abundance, due to land use changes alone. The model showed particular sensitivity to surface roughness, but also to root zone uptake. Scenarios in which land use was modified from agriculture to forest generally resulted in lowest mosquito abundance predictions; classification of the entire domain as rainforest produced a 34% decrease in abundance compared to 2010 results. This study also showed that in addition to vegetation type, spatial proximity of land use change to habitat locations has an impact on mosquito abundance. This modeling approach can be applied to assess impacts of climate and land use conditions that fall outside of the range of previously observed variability.

Diversity, Abundance and Community Structure of Benthic Macro- and Megafauna on the Beaufort Shelf and Slope

PubMed Central

Nephin, Jessica; Juniper, S. Kim; Archambault, Philippe

2014-01-01

Diversity and community patterns of macro- and megafauna were compared on the Canadian Beaufort shelf and slope. Faunal sampling collected 247 taxa from 48 stations with box core and trawl gear over the summers of 2009–2011 between 50 and 1,000 m in depth. Of the 80 macrofaunal and 167 megafaunal taxa, 23% were uniques, present at only one station. Rare taxa were found to increase proportional to total taxa richness and differ between the shelf ( 100 m) where they tended to be sparse and the slope where they were relatively abundant. The macrofauna principally comprised polychaetes with nephtyid polychaetes dominant on the shelf and maldanid polychaetes (up to 92% in relative abundance/station) dominant on the slope. The megafauna principally comprised echinoderms with Ophiocten sp. (up to 90% in relative abundance/station) dominant on the shelf and Ophiopleura sp. dominant on the slope. Macro- and megafauna had divergent patterns of abundance, taxa richness ( diversity) and diversity. A greater degree of macrofaunal than megafaunal variation in abundance, richness and diversity was explained by confounding factors: location (east-west), sampling year and the timing of sampling with respect to sea-ice conditions. Change in megafaunal abundance, richness and diversity was greatest across the depth gradient, with total abundance and richness elevated on the shelf compared to the slope. We conclude that megafaunal slope taxa were differentiated from shelf taxa, as faunal replacement not nestedness appears to be the main driver of megafaunal diversity across the depth gradient. PMID:25007347

Diversity, abundance and community structure of benthic macro- and megafauna on the Beaufort shelf and slope.

PubMed

Nephin, Jessica; Juniper, S Kim; Archambault, Philippe

2014-01-01

Diversity and community patterns of macro- and megafauna were compared on the Canadian Beaufort shelf and slope. Faunal sampling collected 247 taxa from 48 stations with box core and trawl gear over the summers of 2009-2011 between 50 and 1,000 m in depth. Of the 80 macrofaunal and 167 megafaunal taxa, 23% were uniques, present at only one station. Rare taxa were found to increase proportional to total taxa richness and differ between the shelf (< 100 m) where they tended to be sparse and the slope where they were relatively abundant. The macrofauna principally comprised polychaetes with nephtyid polychaetes dominant on the shelf and maldanid polychaetes (up to 92% in relative abundance/station) dominant on the slope. The megafauna principally comprised echinoderms with Ophiocten sp. (up to 90% in relative abundance/station) dominant on the shelf and Ophiopleura sp. dominant on the slope. Macro- and megafauna had divergent patterns of abundance, taxa richness (α diversity) and β diversity. A greater degree of macrofaunal than megafaunal variation in abundance, richness and β diversity was explained by confounding factors: location (east-west), sampling year and the timing of sampling with respect to sea-ice conditions. Change in megafaunal abundance, richness and β diversity was greatest across the depth gradient, with total abundance and richness elevated on the shelf compared to the slope. We conclude that megafaunal slope taxa were differentiated from shelf taxa, as faunal replacement not nestedness appears to be the main driver of megafaunal β diversity across the depth gradient.

Landscape context mediates influence of local food abundance on wetland use by wintering shorebirds in an agricultural valley

USGS Publications Warehouse

Taft, Oriane W.; Haig, Susan M.

2006-01-01

While it is widely understood that local abundance of benthic invertebrates can greatly influence the distribution and abundance of wetland birds, no studies have examined if wetland landscape context can mediate this relationship. We studied the influence of wetland food abundance and landscape context on use of agricultural wetlands by wintering dunlin (Calidris alpina) and killdeer (Charadrius vociferus) in the Willamette Valley of Oregon, USA, over two winters (1999a??2000, 2000a??2001) of differing rainfall and subsequent habitat distribution. We monitored bird use (frequency of occurrence and abundance) at a sample of wetlands differing in local food abundance (density and biomass) and landscape context [adjacent shorebird habitat (defined as ha of wet habitat with less than 50% vegetative cover and within a 2-km radius) and nearest neighbor distance]. We evaluated predictive models for bird use using linear regression and the Cp criterion to select the most parsimonious model. During the dry winter (2000a??2001), dunlin exhibited greater use of sites with higher invertebrate density and biomass but also with more adjacent shorebird habitat and closest to a wetland neighbor. However, neither landscape context nor food abundance were important predictors of dunlin use during the wet winter (1999a??2000). Use of sites by killdeer was unrelated to either local food abundance or landscape context measures during both winters. Our findings contribute to a growing recognition of the importance of landscape structure to wetland birds and highlight a number of implications for the spatial planning and enhancement of wetlands using a landscape approach.

The Impacts of Land Use Change on Malaria Vector Abundance in a Water-Limited Highland Region of Ethiopia

NASA Astrophysics Data System (ADS)

Stryker, J.; Bomblies, A.

2012-12-01

Changes in land use and climate are expected to alter risk of malaria transmission in areas where rainfall limits vector abundance. We use a coupled hydrology-entomology model to investigate the effects of land use change on hydrological processes impacting mosquito abundance in a highland village of Ethiopia. Land use affects partitioning of rainfall into infiltration and runoff that reaches small-scale topographic depressions, which constitute the primary breeding habitat of Anopheles arabiensis mosquitoes. A physically-based hydrology model isolates hydrological mechanisms by which land use impacts pool formation and persistence, and an agent-based entomology model evaluates the response of mosquito populations. This approach reproduced observed interannual variability in mosquito abundance between the 2009 and 2010 wet seasons. Several scenarios of land cover were then evaluated using the calibrated, field-validated model. Model results show variation in pool persistence and depth, as well as in mosquito abundance, due to land use changes alone. The model showed particular sensitivity to surface roughness, but also to root zone uptake. Scenarios in which land use was modified from agriculture to forest generally resulted in lowest mosquito abundance predictions; classification of the entire domain as rainforest produced a 34% decrease in abundance compared to 2010 results. This study also showed that in addition to vegetation type, spatial proximity of land use change to habitat locations has an impact on mosquito abundance. This modeling approach can be applied to assess impacts of climate and land use conditions that fall outside of the range of previously observed variability.

SYSTEMATIC VARIATIONS IN CO{sub 2}/H{sub 2}O ICE ABUNDANCE RATIOS IN NEARBY GALAXIES FOUND WITH AKARI NEAR-INFRARED SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamagishi, M.; Kaneda, H.; Ishihara, D.

2015-07-01

We report CO{sub 2}/H{sub 2}O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5–5.0 μm) spectra. The CO{sub 2}/H{sub 2}O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO{sub 2}/H{sub 2}O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in themore » relation between CO{sub 2}/H{sub 2}O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO{sub 2}/H{sub 2}O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO{sub 2}/H{sub 2}O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO{sub 2}/H{sub 2}O ice abundance ratios tend to be high in young star-forming galaxies.« less

THE MYSTERIOUS CASE OF THE SOLAR ARGON ABUNDANCE NEAR SUNSPOTS IN FLARES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doschek, G. A.; Warren, H. P.

Recently we discussed an enhancement of the abundance of Ar xiv relative to Ca xiv near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar xiv/Ca xiv ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar xiv were observed, and one line was tentatively identified as anmore » Ar xi line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar xi lines, four Ar xiii lines, six Ar xiv lines, and one Ar xv line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.« less

Sea Urchins Predation Facilitates Coral Invasion in a Marine Reserve

PubMed Central

Coma, Rafel; Serrano, Eduard; Linares, Cristina; Ribes, Marta; Díaz, David; Ballesteros, Enric

2011-01-01

Macroalgae is the dominant trophic group on Mediterranean infralittoral rocky bottoms, whereas zooxanthellate corals are extremely rare. However, in recent years, the invasive coral Oculina patagonica appears to be increasing its abundance through unknown means. Here we examine the pattern of variation of this species at a marine reserve between 2002 and 2010 and contribute to the understanding of the mechanisms that allow its current increase. Because indirect interactions between species can play a relevant role in the establishment of species, a parallel assessment of the sea urchin Paracentrotus lividus, the main herbivorous invertebrate in this habitat and thus a key species, was conducted. O. patagonica has shown a 3-fold increase in abundance over the last 8 years and has become the most abundant invertebrate in the shallow waters of the marine reserve, matching some dominant erect macroalgae in abundance. High recruitment played an important role in this increasing coral abundance. The results from this study provide compelling evidence that the increase in sea urchin abundance may be one of the main drivers of the observed increase in coral abundance. Sea urchins overgraze macroalgae and create barren patches in the space-limited macroalgal community that subsequently facilitate coral recruitment. This study indicates that trophic interactions contributed to the success of an invasive coral in the Mediterranean because sea urchins grazing activity indirectly facilitated expansion of the coral. Current coral abundance at the marine reserve has ended the monopolization of algae in rocky infralittoral assemblages, an event that could greatly modify both the underwater seascape and the sources of primary production in the ecosystem. PMID:21789204

Spatial patterns in the abundance of the coastal horned lizard

USGS Publications Warehouse

Fisher, Robert N.; Suarez, Andrew V.; Case, Ted J.

2002-01-01

Coastal horned lizards (   Phrynosoma coronatum) have undergone severe declines in southern California and are a candidate species for state and federal listing under the Endangered Species Act. Quantitative data on their habitat use, abundance, and distribution are lacking, however. We investigated the determinants of abundance for coastal horned lizards at multiple spatial scales throughout southern California. Specifically, we estimated lizard distribution and abundance by establishing 256 pitfall trap arrays clustered within 21 sites across four counties. These arrays were sampled bimonthly for 2–3 years. At each array we measured 26 “local” site descriptors and averaged these values with other “regional” measures to determine site characteristics. Our analyses were successful at identifying factors within and among sites correlated with the presence and abundance of coastal horned lizards. These factors included the absence of the invasive Argentine ant (  Linepithema humile) (and presence of native ant species eaten by the lizards), the presence of chaparral community plants, and the presence of sandy substrates. At a regional scale the relative abundance of Argentine ants was correlated with the relative amount of developed edge around a site. There was no evidence for spatial autocorrelation, even at the scale of the arrays within sites, suggesting that the determinants of the presence or absence and abundance of horned lizard can vary over relatively small spatial scales ( hundreds of meters). Our results suggest that a gap-type approach may miss some of the fine-scale determinants of species abundance in fragmented habitats.

Multi-year and short-term responses of soil ammonia-oxidizing prokaryotes to zinc bacitracin, monensin, and ivermectin, singly or in combination.

PubMed

Magda, Konopka; Hugh A L, Henry; Romain, Marti; Edward, Topp

2015-03-01

A field experiment was initiated whereby a series of replicated plots received annual applications of ivermectin, monensin, and zinc bacitracin, either singly or in a mixture. Pharmaceuticals were added at concentrations of 0.1 mg/kg soil or 10 mg/kg soil. The authors collected soil samples in 2013, before and after the fourth annual application of pharmaceuticals. In addition, a 30-d laboratory experiment was undertaken with the same soil and same pharmaceuticals, but at concentrations of 100 mg/kg soil. The impact of the pharmaceuticals on nitrification rates, on the abundance of ammonia-oxidizing bacteria (AOB), and on the abundance of ammonia-oxidizing archaea (AOA) was assessed. None of the pharmaceuticals at 0.1 mg/kg had any effect on nitrification. Referenced to control soil, nitrification was accelerated in soil exposed to 100 mg/kg zinc bacitracin or 10 mg/kg of the pharmaceutical mixture, but none of the treatments inhibited nitrification. Neither AOB abundance nor AOA abundance was affected by the pharmaceuticals at 0.1 mg/kg. At 10 mg/kg, monensin, zinc bacitracin, and a mixture of all 3 pharmaceuticals suppressed the abundance of AOB, and zinc bacitracin and the mixture increased AOA abundance. The decrease in AOB abundance and increase in AOA abundance when exposed to 10 mg/kg soil suggests that AOB are more sensitive to these chemicals and that AOA populations can expand to occupy the partially vacated niche. Published 2014 SETAC.

Large brown seaweeds of the British Isles: Evidence of changes in abundance over four decades

NASA Astrophysics Data System (ADS)

Yesson, Chris; Bush, Laura E.; Davies, Andrew J.; Maggs, Christine A.; Brodie, Juliet

2015-03-01

The large brown seaweeds (macroalgae) are keystone species in intertidal and shallow subtidal marine ecosystems and are harvested for food and other products. Recently, there have been sporadic, often anecdotal, reports of local abundance declines around the British Isles, but regional surveys have rarely revisited sites to determine possible changes. An assessment was undertaken of changes in the abundance of large brown seaweeds around the British Isles using historical survey data, and determination of whether any changes were linked with climate change. Data were analysed from multiple surveys for 14 habitat-forming and commercially important species of Phaeophyceae, covering orders Laminariales, Fucales and Tilopteridales. Changes in abundance were assessed for sites over the period 1974-2010. Trends in distribution were compared to summer and winter sea surface temperatures (SST). Results revealed regional patterns of both increase and decrease in abundance for multiple species, with significant declines in the south for kelp species and increases in northern and central areas for some kelp and wracks. Abundance patterns of 10 of the 14 species showed a significant association with SSTs, but there was a mixture of positive and negative responses. This is the first British Isles-wide observation of declining abundance of large brown seaweeds. Historical surveys provide useful data to examine trends in abundance, but the ad hoc nature of these studies limit the conclusions that can be drawn. Although the British Isles remains a stronghold for large brown algae, it is imperative that systematic surveys are undertaken to monitor changes.

Galactic Doppelgängers: The Chemical Similarity Among Field Stars and Among Stars with a Common Birth Origin

NASA Astrophysics Data System (ADS)

Ness, M.; Rix, H.-W.; Hogg, David W.; Casey, A. R.; Holtzman, J.; Fouesneau, M.; Zasowski, G.; Geisler, D.; Shetrone, M.; Minniti, D.; Frinchaboy, Peter M.; Roman-Lopes, Alexandre

2018-02-01

We explore to what extent stars within Galactic disk open clusters resemble each other in the high-dimensional space of their photospheric element abundances and contrast this with pairs of field stars. Our analysis is based on abundances for 20 elements, homogeneously derived from APOGEE spectra (with carefully quantified uncertainties of typically 0.03 dex). We consider 90 red giant stars in seven open clusters and find that most stars within a cluster have abundances in most elements that are indistinguishable (in a {χ }2-sense) from those of the other members, as expected for stellar birth siblings. An analogous analysis among pairs of > 1000 field stars shows that highly significant abundance differences in the 20 dimensional space can be established for the vast majority of these pairs, and that the APOGEE-based abundance measurements have high discriminating power. However, pairs of field stars whose abundances are indistinguishable even at 0.03 dex precision exist: ∼0.3% of all field star pairs and ∼1.0% of field star pairs at the same (solar) metallicity [Fe/H] = 0 ± 0.02. Most of these pairs are presumably not birth siblings from the same cluster, but rather doppelgängers. Our analysis implies that “chemical tagging” in the strict sense, identifying birth siblings for typical disk stars through their abundance similarity alone, will not work with such data. However, our approach shows that abundances have extremely valuable information for probabilistic chemo-orbital modeling, and combined with velocities, we have identified new cluster members from the field.

Temporal Variability of Stream Macroinvertebrate Abundance and Biomass Following Pesticide Disturbance

Treesearch

John J. Hutchens; Keun Chung; J. Bruce Wallace

1998-01-01

We determined the extent of macroinvertebrate recovery in a former pesticide-treated stream (FTS) relative to a reference stream (RS) by examining macroinvertebrate colonizing red maple (Acer rubrum L.) litter bags between 5 to 10 y following pesticide treatment. Mean abundance and biomass, varibility in abundance and biomass (using the coefficient...

Mars ozone: Mariner 9 revisited

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1994-01-01

The efficacy of the UV spectroscopy technique used by Mariner 9 to remotely measure ozone abundance at Mars is discussed. Previously-inferred ozone abundances could be underestimated by as much as a factor of 3, and much of the observed variability in the ozone abundance could be due to temporal and spatial variability in cloud and dust amount.

Granivory of invasive, naturalized, and native plants in communities differentially susceptible to invasion

Treesearch

B. M. Connolly; D. E. Pearson; R. N. Mack

2014-01-01

Seed predation is an important biotic filter that can influence abundance and spatial distributions of native species through differential effects on recruitment. This filter may also influence the relative abundance of nonnative plants within habitats and the communities' susceptibility to invasion via differences in granivore identity, abundance, and food...

Field Demonstration of a Broadband Acoustical Backscattering System Mounted on a REMUS-100 for Inferences of Zooplankton Size and Abundance

DTIC Science & Technology

2012-09-30

particularly high, and that numerical abundance of zooplankton was dominated by small copepods that were relatively evenly distributed throughout the water...column. Elastic-shelled pterapods and zooplankton with gas-inclusions were not observed at significant abundances. Small copepods were distributed

An evaluation of multipass electrofishing for estimating the abundance of stream-dwelling salmonids

Treesearch

James T. Peterson; Russell F. Thurow; John W. Guzevich

2004-01-01

Failure to estimate capture efficiency, defined as the probability of capturing individual fish, can introduce a systematic error or bias into estimates of fish abundance. We evaluated the efficacy of multipass electrofishing removal methods for estimating fish abundance by comparing estimates of capture efficiency from multipass removal estimates to capture...

ABUNDANCE OF SEAGRASS (ZOSTERA MARINA L.) AND MACROALGAE IN RELATION TO THE SALINITY-TEMPERATURE GRADIENT IN YAQUINA BAY, OREGON, USA

EPA Science Inventory

The distribution and abundance of the seagrass, Zostera marina, and the associated macroalgae are described for Yaquina Bay, Oregon, U.S.A. Possible relationships between plant abundance and physical-chemical characteristics of the water column were also explored. Study sites w...

Abundance and productivity of birds over an elevational gradient

Treesearch

Kathryn L. Purcell

2002-01-01

This study is investigating the abundance and productivity of birds breeding in four forest types over an elevational gradient in conifer forests of the southern Sierra Nevada of California to identify the most productive habitats for each species, and to examine elevational shifts in abundance, especially as they relate to temperature and precipitation. Species...

Factors influencing stream fish recovery following a large-scale disturbance

Treesearch

William E. Ensign; Angermeier Leftwich; C. Andrew Dolloff

1997-01-01

The authors examined fish distribution and abundance in erosional habitat units in South Fork Roanoke River, VA, following a fish kill by using a reachwide sampling approach for 3 species and a representative-reach sampling approach for 10 species. Qualitative (presence-absence) and quantitative (relative abundance) estimates of distribution and abundance provided...

An abundance analysis of Tau Herculis, B5 IV

NASA Technical Reports Server (NTRS)

Adelman, S. J.

1977-01-01

An abundance analysis of the sharp-lined star Tau Herculis (B5 IV) has been performed using a fully line-blanketed model atmosphere. The derived abundances are similar to those of the sun and the normal main-sequence B stars Iota Her (B3 V) and Nu Cap (B9 V).

Relationships between salmon abundance and tree-ring δ 15N: three objective tests

Treesearch

D.C. Drake; Paul J. Sheppard; Robert J. Naiman

2011-01-01

Quantification of a relationship between salmon escapement in rivers and riparian tree-ring δ 15N could allow reconstruction of prehistorical salmon abundance. Unfortunately, attempts to quantify this link have met with little success. We examined the feasibility of the approach using natural abundance of δ 15...

Viral prevalence increases with regional colony abundance in honey bee drones (Apis mellifera L).

PubMed

Forfert, Nadège; Natsopoulou, Myrsini E; Paxton, Robert J; Moritz, Robin F A

2016-10-01

Transmission among colonies is a central feature for the epidemiology of honey bee pathogens. High colony abundance may promote transmission among colonies independently of apiary layout, making colony abundance a potentially important parameter determining pathogen prevalence in populations of honey bees. To test this idea, we sampled male honey bees (drones) from seven distinct drone congregation areas (DCA), and used their genotypes to estimate colony abundance at each site. A multiplex ligation dependent probe amplification assay (MLPA) was used to assess the prevalence of ten viruses, using five common viral targets, in individual drones. There was a significant positive association between colony abundance and number of viral infections. This result highlights the potential importance of high colony abundance for pathogen prevalence, possibly because high population density facilitates pathogen transmission. Pathogen prevalence in drones collected from DCAs may be a useful means of estimating the disease status of a population of honey bees during the mating season, especially for localities with a large number of wild or feral colonies. Copyright © 2016 Elsevier B.V. All rights reserved.

Relationships between protein-encoding gene abundance and corresponding process are commonly assumed yet rarely observed

USGS Publications Warehouse

Rocca, Jennifer D.; Hall, Edward K.; Lennon, Jay T.; Evans, Sarah E.; Waldrop, Mark P.; Cotner, James B.; Nemergut, Diana R.; Graham, Emily B.; Wallenstein, Matthew D.

2015-01-01

For any enzyme-catalyzed reaction to occur, the corresponding protein-encoding genes and transcripts are necessary prerequisites. Thus, a positive relationship between the abundance of gene or transcripts and corresponding process rates is often assumed. To test this assumption, we conducted a meta-analysis of the relationships between gene and/or transcript abundances and corresponding process rates. We identified 415 studies that quantified the abundance of genes or transcripts for enzymes involved in carbon or nitrogen cycling. However, in only 59 of these manuscripts did the authors report both gene or transcript abundance and rates of the appropriate process. We found that within studies there was a significant but weak positive relationship between gene abundance and the corresponding process. Correlations were not strengthened by accounting for habitat type, differences among genes or reaction products versus reactants, suggesting that other ecological and methodological factors may affect the strength of this relationship. Our findings highlight the need for fundamental research on the factors that control transcription, translation and enzyme function in natural systems to better link genomic and transcriptomic data to ecosystem processes.

Diel variation of larval fish abundance in the Amazon and Rio Negro.

PubMed

Araujo-Lima, C A; da Silva, V V; Petry, P; Oliveira, E C; Moura, S M

2001-08-01

Many streams and large rivers present higher ichthyoplankton densities at night. However, in some rivers this does not occur and larvae are equally abundant during the day. Larval drift diel variation is an important information for planning sampling programs for evaluating larval distribution and production. The aim of this study was to test whether the abundance of larval fish was different at either period. We tested it by comparing day and night densities of characiform, clupeiform and siluriform larvae during five years in the Amazon and one year in Rio Negro. We found that larvae of three species of characiform and larvae of siluriform were equally abundant during day and night in the Amazon. Conversely, the catch of Pellona spp. larvae was significantly higher during the day. In Rio Negro, however, larval abundance was higher during the night. These results imply that day samplings estimate adequately the abundance of these characiform and siluriform larvae in the Amazon, but not Pellona larvae. Evaluations of larved densities of Rio Negro will have to consider night sampling.

Hierarchical models of animal abundance and occurrence

USGS Publications Warehouse

Royle, J. Andrew; Dorazio, R.M.

2006-01-01

Much of animal ecology is devoted to studies of abundance and occurrence of species, based on surveys of spatially referenced sample units. These surveys frequently yield sparse counts that are contaminated by imperfect detection, making direct inference about abundance or occurrence based on observational data infeasible. This article describes a flexible hierarchical modeling framework for estimation and inference about animal abundance and occurrence from survey data that are subject to imperfect detection. Within this framework, we specify models of abundance and detectability of animals at the level of the local populations defined by the sample units. Information at the level of the local population is aggregated by specifying models that describe variation in abundance and detection among sites. We describe likelihood-based and Bayesian methods for estimation and inference under the resulting hierarchical model. We provide two examples of the application of hierarchical models to animal survey data, the first based on removal counts of stream fish and the second based on avian quadrat counts. For both examples, we provide a Bayesian analysis of the models using the software WinBUGS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.; Kucharek, H.; Möbius, E.

In this paper we report on a two-year study to estimate the Ne/O abundance ratio in the gas phase of the local interstellar cloud (LIC). Based on the first two years of observations with the Interstellar Boundary Explorer, we determined the fluxes of interstellar neutral (ISN) O and Ne atoms at the Earth's orbit in spring 2009 and 2010. A temporal variation of the Ne/O abundance ratio at the Earth's orbit could be expected due to solar cycle-related effects such as changes of ionization. However, this study shows that there is no significant change in the Ne/O ratio at themore » Earths orbit from 2009 to 2010. We used time-dependent survival probabilities of the ISNs to calculate the Ne/O abundance ratio at the termination shock. Then we estimated the Ne/O abundance ratio in the gas phase of the LIC with the use of filtration factors and the ionization fractions. From our analysis, the Ne/O abundance ratio in the LIC is 0.33 ± 0.07, which is in agreement with the abundance ratio inferred from pickup-ion measurements.« less

Abundance of Chemical Elements in RR Lyrae Variables and their Kinematic Parameters

NASA Astrophysics Data System (ADS)

Gozha, M. L.; Marsakov, V. A.; Koval', V. V.

2018-03-01

A catalog of the chemical and spatial-kinematic parameters of 415 RR Lyrae variables (Lyrids) in the galactic field is compiled. Spectroscopic determinations of the relative abundances of 13 chemical elements in 101 of the RR Lyrae variables are collected from 25 papers published between 1995 and 2017. The data from different sources are reduced to a single solar abundance scale. The mean weighted chemical abundances are calculated with coefficients inversely proportional to the reported errors. An analysis of the deviations in the published relative abundances in each star from the mean square values calculated from them reveals an absence of systematic biases among the results from the various articles. The rectangular coordinates of 407 of the RR Lyrae variables and the components of the three-dimensional (3D) velocities of 401 of the stars are calculated using data from several sources. The collected data on the abundances of chemical elements produced by various nuclear fusion processes for the RR Lyrae variables of the field, as well as the calculated 3D velocities, can be used for studying the evolution of the Galaxy.

Seasonal variation in denitrification and dissimilatory nitrate reduction to ammonia process rates and corresponding key functional genes along an estuarine nitrate gradient

PubMed Central

Smith, Cindy J.; Dong, Liang F.; Wilson, John; Stott, Andrew; Osborn, A. Mark; Nedwell, David B.

2015-01-01

This research investigated spatial-temporal variation in benthic bacterial community structure, rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes and abundances of corresponding genes and transcripts at three sites—the estuary-head, mid-estuary and the estuary mouth (EM) along the nitrate gradient of the Colne estuary over an annual cycle. Denitrification rates declined down the estuary, while DNRA rates were higher at the estuary head and middle than the EM. In four out of the six 2-monthly time-points, rates of DNRA were greater than denitrification at each site. Abundance of gene markers for nitrate-reduction (nitrate reductase narG and napA), denitrification (nitrite reductase nirS) and DNRA (DNRA nitrite reductase nrfA) declined along the estuary with significant relationships between denitrification and nirS abundance, and DNRA and nrfA abundance. Spatially, rates of denitrification, DNRA and corresponding functional gene abundances decreased along the estuary. However, temporal correlations between rate processes and functional gene and transcript abundances were not observed. PMID:26082763

Long-term change in the megabenthos of the Porcupine Abyssal Plain (NE Atlantic)

NASA Astrophysics Data System (ADS)

Billett, D. S. M.; Bett, B. J.; Rice, A. L.; Thurston, M. H.; Galéron, J.; Sibuet, M.; Wolff, G. A.

A radical change in the abundance of invertebrate megafauna on the Porcupine Abyssal Plain is reported over a period of 10 years (1989-1999). Actiniarians, annelids, pycnogonids, tunicates, ophiuroids and holothurians increased significantly in abundance. However, there was no significant change in wet weight biomass. Two holothurian species, Amperima rosea and Ellipinion molle, increased in abundance by more than two orders of magnitude. Samples from the Porcupine Abyssal Plain over a longer period (1977-1999) show that prior to 1996 these holothurian species were always a minor component of the megafauna. From 1996 to 1999 A. rosea was abundant over a wide area of the Porcupine Abyssal Plain indicating that the phenomenon was not a localised event. Several dominant holothurian species show a distinct trend in decreasing body size over the study period. The changes in megafauna abundance may be related to environmental forcing (food supply) rather than to localised stochastic population variations. Inter-annual variability and long-term trends in organic matter supply to the seabed may be responsible for the observed changes in abundance, species dominance and size distributions.

Elemental Abundances of Blue Compact Dwarfs from Mid-Infrared Spectroscopy with Spitzer

NASA Astrophysics Data System (ADS)

Wu, Yanling; Bernard-Salas, J.; Charmandaris, V.; Lebouteiller, V.; Hao, Lei; Brandl, B. R.; Houck, J. R.

2008-01-01

We present a study of elemental abundances in a sample of 13 blue compact dwarf (BCD) galaxies, using the ~10-37 μm high-resolution spectra obtained with Spitzer IRS. We derive the abundances of neon and sulfur for our sample using the infrared fine-structure lines probing regions which may be obscured by dust in the optical and compare our results with similar infrared studies of starburst galaxies from ISO. We find a good correlation between the neon and sulfur abundances, although sulfur is underabundant relative to neon with respect to the solar value. A comparison of the elemental abundances (neon and sulfur) measured from the infrared data with those derived from the optical (neon, sulfur, and oxygen) studies reveals a good overall agreement for sulfur, while the infrared-derived neon abundances are slightly higher than the optical values. This indicates either that the metallicities of dust-enshrouded regions in BCDs are similar to the optically accessible regions, or that if they are different they do not contribute substantially to the total infrared emission of the host galaxy.

Depletion of highly abundant proteins in blood plasma by ammonium sulfate precipitation for 2D-PAGE analysis.

PubMed

Mahn, Andrea; Ismail, Maritza

2011-11-15

Ammonium sulfate precipitation (ASP) was explored as a method for depleting some highly abundant proteins from blood plasma, in order to reduce the dynamic range of protein concentration and to improve the detection of low abundance proteins by 2D-PAGE. 40% ammonium sulfate saturation was chosen since it allowed depleting 39% albumin and 82% α-1-antitrypsin. ASP-depletion showed high reproducibility in 2D-PAGE analysis (4.2% variation in relative abundance of albumin), similar to that offered by commercial affinity-depletion columns. Besides, it allowed detecting 59 spots per gel, very close to the number of spots detected in immuno-affinity-depleted plasma. Thus, ASP at 40% saturation is a reliable depletion method that may help in proteomic analysis of blood plasma. Finally, ASP-depletion seems to be complementary to hydrophobic interaction chromatography (HIC)-depletion, and therefore an ASP-step followed by a HIC-step could probably deplete the most highly abundant plasma proteins, thus improving the detection of low abundance proteins by 2D-PAGE. Copyright © 2011 Elsevier B.V. All rights reserved.

Why abundant tropical tree species are phylogenetically old.

PubMed

Wang, Shaopeng; Chen, Anping; Fang, Jingyun; Pacala, Stephen W

2013-10-01

Neutral models of species diversity predict patterns of abundance for communities in which all individuals are ecologically equivalent. These models were originally developed for Panamanian trees and successfully reproduce observed distributions of abundance. Neutral models also make macroevolutionary predictions that have rarely been evaluated or tested. Here we show that neutral models predict a humped or flat relationship between species age and population size. In contrast, ages and abundances of tree species in the Panamanian Canal watershed are found to be positively correlated, which falsifies the models. Speciation rates vary among phylogenetic lineages and are partially heritable from mother to daughter species. Variable speciation rates in an otherwise neutral model lead to a demographic advantage for species with low speciation rate. This demographic advantage results in a positive correlation between species age and abundance, as found in the Panamanian tropical forest community.

Mesoscale eddies and T richodesmium spp. distributions in the southwestern North Atlantic

PubMed Central

McGillicuddy, Dennis J.; Flierl, Glenn R.; Davis, Cabell S.; Dyhrman, Sonya T.; Waterbury, John B.

2015-01-01

Abstract Correlations of Trichodesmium colony abundance with the eddy field emerged in two segments of Video Plankton Recorder observations made in the southwestern North Atlantic during fall 2010 and spring 2011. In fall 2010, local maxima in abundance were observed in cyclones. We hypothesized surface Ekman transport convergence as a mechanism for trapping buoyant colonies in cyclones. Idealized models supported the potential of this process to influence the distribution of buoyant colonies over time scales of several months. In spring 2011, the highest vertically integrated colony abundances were observed in anticyclones. These peaks in abundance correlated with anomalously fresh water, suggesting riverine input as a driver of the relationship. These contrasting results in cyclones and anticyclones highlight distinct mechanisms by which mesoscale eddies can influence the abundance and distribution of Trichodesmium populations of the southwestern North Atlantic. PMID:26937328

A lacustrine carbonate record of Holocene seasonality and climate

USGS Publications Warehouse

Wittkop, Chad A.; Teranes, Jane L.; Dean, Walter E.; Guilderson, Thomas P.

2009-01-01

Annually laminated (varved) Holocene sediments from Derby Lake, Michigan, display variations in endogenic calcite abundance reflecting a long-(millennial-scale) decrease in burial punctuated with frequent short- (decadal-scale) oscillations due to carbonate dissolution. Since 6000 cal yr B.P., sediment carbonate abundance has followed a decreasing trend while organic-carbon abundance has increased. The correlation between organic-carbon abundance and the sum of March-April-October-November insolation has an r2 value of 0.58. We interpret these trends to represent a precession-driven lengthening of the Holocene growing season that has reduced calcite burial by enhancing net annual organic-matter production and associated calcite dissolution. Correlations with regional paleoclimate records suggest that changes in temperature and moisture balance have impacted the distribution of short- oscillations in carbonate and organic-matter abundance superimposed on the precession-driven trends.

Solar wind composition from sector boundary crossings and coronal mass ejections

NASA Technical Reports Server (NTRS)

Ogilvie, K. W.; Coplan, M. A.; Geiss, J.

1992-01-01

Using the Ion Composition Instrument (ICI) on board the ISEE-3/ICE spacecraft, average abundances of He-4, He-3, O, Ne, Si, and Fe have been determined over extended periods. In this paper the abundances of He-4, O, Ne, Si, and Mg obtained by the ICI in the region of sector boundary crossings (SBCs), magnetic clouds and bidirectional streaming events (BDSs) are compared with the average abundances. Both magnetic clouds and BDSs are associated with coronal mass ejections (CMEs). No variation of abundance is seen to occur at SBCs except for helium, as has already been observed. In CME-related material, the abundance of neon appears to be high and variable, in agreement with recent analysis of spectroscopic observations of active regions. We find that our observations can be correlated with the magnetic topology in the corona.

Optical determination of material abundances by using neural networks for the derivation of spectral filters

NASA Astrophysics Data System (ADS)

Krippner, Wolfgang; Wagner, Felix; Bauer, Sebastian; Puente León, Fernando

2017-06-01

Using appropriately designed spectral filters allows to optically determine material abundances. While an infinite number of possibilities exist for determining spectral filters, we take advantage of using neural networks to derive spectral filters leading to precise estimations. To overcome some drawbacks that regularly influence the determination of material abundances using hyperspectral data, we incorporate the spectral variability of the raw materials into the training of the considered neural networks. As a main result, we successfully classify quantized material abundances optically. Thus, the main part of the high computational load, which belongs to the use of neural networks, is avoided. In addition, the derived material abundances become invariant against spatially varying illumination intensity as a remarkable benefit in comparison with spectral filters based on the Moore-Penrose pseudoinverse, for instance.

Developing ISM Dust Grain Models with Precision Elemental Abundances from IXO

NASA Technical Reports Server (NTRS)

Valencic, L. A.; Smith, R. K.; Juet, A.

2009-01-01

The exact nature of interstellar dust grains in the Galaxy remains mysterious, despite their ubiquity. Many viable models exist, based on available IR-UV data and assumed elemental abundances. However, the abundances, which are perhaps the most stringent constraint, are not well known: modelers must use proxies in the absence of direct measurements for the diffuse interstellar medium (ISM). Recent revisions of these proxy values have only added to confusion over which is the best representative for the diffuse ISM, and highlighted the need for direct, high signal-to-noise measurements from the ISM itself. The International X-ray Observatory's superior facilities will enable high-precision elemental abundance measurements. We ill show how these results will measure both the overall ISM abundances and challenge dust models, allowing us to construct a more realistic picture of the ISM.

VizieR Online Data Catalog: Neutron-capture elements abundances in Cepheids (da Silva+ 2016)

NASA Astrophysics Data System (ADS)

da Silva, R.; Lemasle, B.; Bono, G.; Genovali, K.; McWilliam, A.; Cristallo, S.; Bergemann, M.; Buonanno, R.; Fabrizio, M.; Ferraro, I.; Francois, P.; Iannicola, G.; Inno, L.; Laney, C. D.; Kudritzki, R.-P.; Matsunaga, N.; Nonino, M.; Primas, F.; Przybilla, N.; Romaniello, M.; Thevenin, F.; Urbaneja, M. A.

2015-11-01

The abundances of Fe, Y, La, Ce, Nd, and Eu for our sample of 73 Cepheids plus data available in the literature for other 362 Cepheids are shown. We first show the abundances derived based on individual spectra for the 73 stars, then the averaged values, and finally the data from the literature. The original abundances available in the literature were rescaled according to the zero-point differences listed in Table 5. The priority was given in the following order: we first adopt the abundances provided by our group, this study (TS) and Lemasle et al. (2013A&A...558A..31L, LEM), and then those provided by the other studies, Luck & Lambert (2011AJ....142..136L, LIII), and Luck et al. (2011AJ....142...51L, LII). (4 data files).

Vertical distribution of pigmented and non-pigmented nanoflagellates in the East China Sea

NASA Astrophysics Data System (ADS)

Tsai, Sheng-Fang; Lin, Fan-Wei; Chan, Ya-Fan; Chiang, Kuo-Ping

2016-08-01

Nanoflagellates can be separated into two groups according to their trophic mode, i.e. pigmented nanoflagellates (PNF) and heterotrophic nanoflagellates (HNF). However, a newly identified group, mixotrophic nanoflagellates (MNF), are pigmented and show the ability of prey on bacteria. To examine the vertical variations in PNF and HNF abundances, as well as their relationships and the nutritional strategies that they might use, two summer cruises were undertaken in the East China Sea in July 2011 (OR1 966) and July 2012 (OR1 1004). The results show that both HNF and PNF abundances decline with increasing water depth. Vertical variations of abundances are believed to be influenced by prey and light, for HNF and PNF respectively. Over a large part of the sampling area, the ratio of PNF to HNF abundances is about 1:1 in the disphotic and euphotic zones, but exceeds 1.5 in the nutrient-depleted environment along the margin of the continental shelf. The correlation between PNF abundance and bacteria/Synechococcus abundance is positive where PNF/HNF >1.5. However, there is no significant correlation between PNF/HNF abundance when PNF/HNF >1.5 and light/nutrients, indicating that vertical distributions are influenced mainly by prey (bacteria and Synechococcus) in the nutrient-depleted environment. This study assumes that PNF consists mostly of MNF. In the euphotic zone they receive energy from photosynthesis, which is stimulated by the available nutrients from grazing. Their abundance is thus higher than that of HNF. However, in the disphotic zone, both PNF and HNF satisfy their nutrient demands by grazing, and PNF/HNF is close to 1. In other words, mixotrophy might be the main trophic mode for PNF in the nutrient-depleted, oligotrophic environment. Meanwhile, in deeper water (300 m), the much lower prey density means that MNF cannot satisfy the basic energy demands of metabolism and photosynthesis, and thus HNF abundance exceeds that of PNF.

The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

PubMed Central

Codesido, Mariano; Abba, Agustín M.; Bilenca, David

2017-01-01

Abstract In temperate agroecosystems, avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices. We assessed the seasonal roles of field type, field use in the surroundings, and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000 km2 study area in the Pampas of central Argentina. During spring-summer and autumn of 2011–2013, we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species. We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species. We used generalized lineal mixed models to relate bird abundance to field type, field use in the surroundings, and distance to the nearest woodlot. In spring-summer (breeding season) most bird responses were associated with their nesting requirements. Species that build their nests in trees, such as eared doves Zenaida auriculata, picazuro pigeons Patagioenas picazuro, and monk parakeets Myiopsitta monachus, were more abundant in fields closer to woodlots, whereas grassland yellow-finches Sicalis luteola, which nest at areas with tall grasses, were more abundant in fields with livestock use patches in the field surroundings. In autumn (non-breeding season), most bird responses were associated with foraging and refuge needs. The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources. In addition, both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots, which provide suitable roosting sites. Our results show that in temperate agroecosystems, the relationships between field characteristics and seed-eating bird abundances vary with season. PMID:29491986

Late-Quaternary variation in C3 and C4 grass abundance in southeastern Australia as inferred from δ13C analysis: Assessing the roles of climate, pCO2, and fire

NASA Astrophysics Data System (ADS)

Nelson, David M.; Urban, Michael A.; Kershaw, A. Peter; Hu, Feng Sheng

2016-05-01

Climate, atmospheric pCO2, and fire all may exert major influences on the relative abundance of C3 and C4 grasses in the present-day vegetation. However, the relative role of these factors in driving variation in C3 and C4 grass abundances in the paleorecord is uncertain, and C4 abundance is often interpreted narrowly as a proxy indicator of aridity or pCO2. We measured δ13C values of individual grains of grass (Poaceae) pollen in the sediments of two sites in southeastern Australia to assess changes in the proportions of C3 and C4 grasses during the past 25,000 years. These data were compared with shifts in pCO2, temperature, moisture balance, and fire to assess how these factors were related to long-term variation of C4 grass abundance during the late Quaternary. At Caledonia Fen, a high-elevation site in the Snowy Mountains, C4 grass abundance decreased from an average of 66% during the glacial period to 11% during the Holocene, primarily in response to increased pCO2 and temperature. In contrast, this pattern did not exist in low-elevation savannah woodlands around Tower Hill Northwest Crater, where C4 grass abundance instead varied in response to shifts in regional aridity. Fire did not appear to have strongly influenced the proportions of C3 and C4 grasses on the landscape at millennial timescales at either site. These patterns are similar to those of a recent study in East Africa, suggesting that elevation-related climatic differences influence how the abundance of C3 and C4 grasses responds to shifts in climate and pCO2. These results caution against using C4 plant abundance as a proxy indicator of either climate or pCO2 without an adequate understanding of key controlling factors.

Prospecting for Precious Metals in Ultra-Metal-Poor Stars

NASA Astrophysics Data System (ADS)

French, R. S.

2000-05-01

The chemical compositions of the most metal-poor halo stars are living records of the very early nucleosynthetic history of the Galaxy. Only a few prior generations, if not a single one, of element-donating supernovae could have been responsible for the heavy elements observed in ultra-metal-poor (UMP; [Fe/H] < --2.5) stars. Abundances of the heavy neutron-capture elements (Z > 30) can yield direct information about the supernova progenitors to UMP stars, and abundances of unstable thorium and uranium (Z = 90, 92) can potentially provide age estimates for the Galactic halo. Already, many studies have demonstrated that abundances of rare-earth elements (56 <= Z <= 72) in UMP stars are completely consistent with their production in rapid neutron-capture synthesis (r-process) events, usually believed to occur during supernovae explosions. Therefore, mapping the entire abundance pattern of UMP stars is of significant interest. In particular, abundances of the most massive stable elements (Os -> Pb or 76 <= Z <= 82) could provide crucial information about the so-called ``third r-process peak,'' and are critical to the radioactive-dating technique that uses unstable thorium as a chronometer. Until recently, abundance determinations for these elements have been virtually non-existent, as the strongest relevant transitions lay in the vacuum UV, inaccessible to ground-based observation. The availability of high-resolution space-based spectrometers has opened up new regions of spectral coverage, including precisely the range in wavelength needed to make these sensitive measurements. We have undertaken a study of about 10 metal-poor halo giants to determine the abundances of several of the heaviest neutron-capture elements including platinum, osmium, lead, and gold. Preliminary results indicate that the abundance pattern of heavy neutron-capture elements (56 <= Z <= 82) in UMP stars does mimic a scaled solar system r-process. Thus, the ability to estimate the initial abundances of thorium and uranium is greatly reinforced.

p-capture reaction cycles in rotating massive stars and their impact on elemental abundances in globular cluster stars: A case study of O, Na and Al

NASA Astrophysics Data System (ADS)

Mahanta, Upakul; Goswami, Aruna; Duorah, Hiralal; Duorah, Kalpana

2017-08-01

Elemental abundance patterns of globular cluster stars can provide important clues for understanding cluster formation and early chemical evolution. The origin of the abundance patterns, however, still remains poorly understood. We have studied the impact of p-capture reaction cycles on the abundances of oxygen, sodium and aluminium considering nuclear reaction cycles of carbon-nitrogen-oxygen-fluorine, neon-sodium and magnesium-aluminium in massive stars in stellar conditions of temperature range 2×107 to 10×107 K and typical density of 102 gm cc-1. We have estimated abundances of oxygen, sodium and aluminium with respect to Fe, which are then assumed to be ejected from those stars because of rotation reaching a critical limit. These ejected abundances of elements are then compared with their counterparts that have been observed in some metal-poor evolved stars, mainly giants and red giants, of globular clusters M3, M4, M13 and NGC 6752. We observe an excellent agreement with [O/Fe] between the estimated and observed abundance values for globular clusters M3 and M4 with a correlation coefficient above 0.9 and a strong linear correlation for the remaining two clusters with a correlation coefficient above 0.7. The estimated [Na/Fe] is found to have a correlation coefficient above 0.7, thus implying a strong correlation for all four globular clusters. As far as [Al/Fe] is concerned, it also shows a strong correlation between the estimated abundance and the observed abundance for globular clusters M13 and NGC 6752, since here also the correlation coefficient is above 0.7 whereas for globular cluster M4 there is a moderate correlation found with a correlation coefficient above 0.6. Possible sources of these discrepancies are discussed.

Citizen science identifies the effects of nitrogen deposition, climate and tree species on epiphytic lichens across the UK.

PubMed

Welden, N A; Wolseley, P A; Ashmore, M R

2018-01-01

A national citizen survey quantified the abundance of epiphytic lichens that are known to be either sensitive or tolerant to nitrogen (N) deposition. Records were collected across the UK from over 10,000 individual trees of 22 deciduous species. Mean abundance of tolerant and sensitive lichens was related to mean N deposition rates and climatic variables at a 5 km scale, and the response of lichens was compared on the three most common trees (Quercus, Fraxinus and Acer) and by assigning all 22 tree species to three bark pH groups. The abundance of N-sensitive lichens on trunks decreased with increasing total N deposition, while that of N-tolerant lichens increased. The abundance of N-sensitive lichens on trunks was reduced close to a busy road, while the abundance of N-tolerant lichens increased. The abundance of N-tolerant lichen species on trunks was lower on Quercus and other low bark pH species, but the abundance of N-sensitive lichens was similar on different tree species. Lichen abundance relationships with total N deposition did not differ between tree species or bark pH groups. The response of N-sensitive lichens to reduced nitrogen was greater than to oxidised N, and the response of N-tolerant lichens was greater to oxidised N than to reduced N. There were differences in the response of N-sensitive and N-tolerant lichens to rainfall, humidity and temperature. Relationships with N deposition and climatic variables were similar for lichen presence on twigs as for lichen abundance on trunks, but N-sensitive lichens increased, rather than decreased, on twigs of Quercus/low bark pH species. The results demonstrate the unique power of citizen science to detect and quantify the air pollution impacts over a wide geographical range, and specifically to contribute to understanding of lichen responses to different chemical forms of N deposition, local pollution sources and bark chemistry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fish wariness is a more sensitive indicator to changes in fishing pressure than abundance, length or biomass.

PubMed

Goetze, Jordan S; Januchowski-Hartley, Fraser A; Claudet, Joachim; Langlois, Tim J; Wilson, Shaun K; Jupiter, Stacy D

2017-06-01

Identifying the most sensitive indicators to changes in fishing pressure is important for accurately detecting impacts. Biomass is thought to be more sensitive than abundance and length, while the wariness of fishes is emerging as a new metric. Periodically harvested closures (PHCs) that involve the opening and closing of an area to fishing are the most common form of fisheries management in the western Pacific. The opening of PHCs to fishing provides a unique opportunity to compare the sensitivity of metrics, such as abundance, length, biomass and wariness, to changes in fishing pressure. Diver-operated stereo video (stereo-DOV) provides data on fish behavior (using a proxy for wariness, minimum approach distance) simultaneous to abundance and length estimates. We assessed the impact of PHC protection and harvesting on the abundance, length, biomass, and wariness of target species using stereo-DOVs. This allowed a comparison of the sensitivity of these metrics to changes in fishing pressure across four PHCs in Fiji, where spearfishing and fish drives are common. Before PHCs were opened to fishing they consistently decreased the wariness of targeted species but were less likely to increase abundance, length, or biomass. Pulse harvesting of PHCs resulted in a rapid increase in the wariness of fishes but inconsistent impacts across the other metrics. Our results suggest that fish wariness is the most sensitive indicator of fishing pressure, followed by biomass, length, and abundance. The collection of behavioral data simultaneously with abundance, length, and biomass estimates using stereo-DOVs offers a cost-effective indicator of protection or rapid increases in fishing pressure. Stereo-DOVs can rapidly provide large amounts of behavioral data from monitoring programs historically focused on estimating abundance and length of fishes, which is not feasible with visual methods. © 2017 by the Ecological Society of America.

Productivity and fishing pressure drive variability in fish parasite assemblages of the Line Islands, equatorial Pacific.

PubMed

Wood, Chelsea L; Baum, Julia K; Reddy, Sheila M W; Trebilco, Rowan; Sandin, Stuart A; Zgliczynski, Brian J; Briggs, Amy A; Micheli, Fiorenza

2015-05-01

Variability in primary productivity and fishing pressure can shape the abundance, species composition, and diversity of marine life. Though parasites comprise nearly half of marine species, their responses to these important forces remain little explored. We quantified parasite assemblages at two spatial scales, across a gradient in productivity and fishing pressure that spans six coral islands of the Line Islands archipelago and within the largest Line Island, Kiritimati, which experiences a west-to-east gradient in fishing pressure and upwelling-driven productivity. In the across-islands data set, we found that increasing productivity was correlated with increased parasite abundance overall, but that the effects of productivity differed among parasite groups. Trophically transmitted parasites increased in abundance with increasing productivity, but directly transmitted parasites did not exhibit significant changes. This probably arises because productivity has stronger effects on the abundance of the planktonic crustaceans and herbivorous snails that serve as the intermediate hosts of trophically transmitted parasites than on the higher-trophic level fishes that are the sole hosts of directly transmitted parasites. We also found that specialist parasites increased in response to increasing productivity, while generalists did not, possibly because specialist parasites tend to be more strongly limited by host availability than are generalist parasites. After the effect of productivity was controlled for, fishing was correlated with decreases in the abundance of trophically transmitted parasites, while directly transmitted parasites appeared to track host density; we observed increases in the abundance of parasites using hosts that experienced fishing-driven compensatory increases in abundance. The within-island data set confirmed these patterns for the combined effects of productivity and fishing on parasite abundance, suggesting that our conclusions are robust across a span of spatial scales. Overall, these results indicate that there are strong and variable effects of anthropogenic and natural drivers on parasite abundance and taxonomic richness. These effects are likely to be mediated by parasite traits, particularly by parasite transmission strategies.

Finding a fox: an evaluation of survey methods to estimate abundance of a small desert carnivore.

PubMed

Dempsey, Steven J; Gese, Eric M; Kluever, Bryan M

2014-01-01

The status of many carnivore species is a growing concern for wildlife agencies, conservation organizations, and the general public. Historically, kit foxes (Vulpes macrotis) were classified as abundant and distributed in the desert and semi-arid regions of southwestern North America, but is now considered rare throughout its range. Survey methods have been evaluated for kit foxes, but often in populations where abundance is high and there is little consensus on which technique is best to monitor abundance. We conducted a 2-year study to evaluate four survey methods (scat deposition surveys, scent station surveys, spotlight survey, and trapping) for detecting kit foxes and measuring fox abundance. We determined the probability of detection for each method, and examined the correlation between the relative abundance as estimated by each survey method and the known minimum kit fox abundance as determined by radio-collared animals. All surveys were conducted on 15 5-km transects during the 3 biological seasons of the kit fox. Scat deposition surveys had both the highest detection probabilities (p = 0.88) and were most closely related to minimum known fox abundance (r2 = 0.50, P = 0.001). The next best method for kit fox detection was the scent station survey (p = 0.73), which had the second highest correlation to fox abundance (r2 = 0.46, P<0.001). For detecting kit foxes in a low density population we suggest using scat deposition transects during the breeding season. Scat deposition surveys have low costs, resilience to weather, low labor requirements, and pose no risk to the study animals. The breeding season was ideal for monitoring kit fox population size, as detections consisted of the resident population and had the highest detection probabilities. Using appropriate monitoring techniques will be critical for future conservation actions for this rare desert carnivore.

Can Occupancy–Abundance Models Be Used to Monitor Wolf Abundance?

PubMed Central

Latham, M. Cecilia; Latham, A. David M.; Webb, Nathan F.; Mccutchen, Nicole A.; Boutin, Stan

2014-01-01

Estimating the abundance of wild carnivores is of foremost importance for conservation and management. However, given their elusive habits, direct observations of these animals are difficult to obtain, so abundance is more commonly estimated from sign surveys or radio-marked individuals. These methods can be costly and difficult, particularly in large areas with heavy forest cover. As an alternative, recent research has suggested that wolf abundance can be estimated from occupancy–abundance curves derived from “virtual” surveys of simulated wolf track networks. Although potentially more cost-effective, the utility of this approach hinges on its robustness to violations of its assumptions. We assessed the sensitivity of the occupancy–abundance approach to four assumptions: variation in wolf movement rates, changes in pack cohesion, presence of lone wolves, and size of survey units. Our simulations showed that occupancy rates and wolf pack abundances were biased high if track surveys were conducted when wolves made long compared to short movements, wolf packs were moving as multiple hunting units as opposed to a cohesive pack, and lone wolves were moving throughout the surveyed landscape. We also found that larger survey units (400 and 576 km2) were more robust to changes in these factors than smaller survey units (36 and 144 km2). However, occupancy rates derived from large survey units rapidly reached an asymptote at 100% occupancy, suggesting that these large units are inappropriate for areas with moderate to high wolf densities (>15 wolves/1,000 km2). Virtually-derived occupancy–abundance relationships can be a useful method for monitoring wolves and other elusive wildlife if applied within certain constraints, in particular biological knowledge of the surveyed species needs to be incorporated into the design of the occupancy surveys. Further, we suggest that the applicability of this method could be extended by directly incorporating some of its assumptions into the modelling framework. PMID:25054199

Long-term annual and monthly changes in mysids and caridean decapods in a macrotidal estuarine environment in relation to climate change and pollution

NASA Astrophysics Data System (ADS)

Plenty, Shaun J.; Tweedley, James R.; Bird, David J.; Newton, Lyn; Warwick, Richard M.; Henderson, Peter A.; Hall, Norm G.; Potter, Ian C.

2018-07-01

A 26-year time series of monthly samples from the water intake of a power station has been used to analyse the trends exhibited by number of species, total abundance, and composition of the mysids and caridean decapods in the inner Bristol Channel. During this period, annual water temperatures, salinities and the North Atlantic Oscillation Index (NAOI) in winter did not change significantly, whereas annual NAOI declined. Annual mean monthly values for the number of species and total abundance both increased over the 26 years, but these changes were not correlated with any of the measured physico-chemical/climatic factors. As previous studies demonstrated that, during a similar period, metal concentrations in the Severn Estuary and Bristol Channel (into which that estuary discharges) declined and water quality increased, it is proposed that the above changes are due to an improved environment. The fauna was dominated by the mysids Mesopodopsis slabberi and Schistomysis spiritus, which collectively contributed 94% to total abundance. Both species, which were represented by juveniles, males, non-brooding females and brooding females, underwent statistically-indistinguishable patterns of change in abundance over the 26 years. When analysis was based on the abundances of the various species, the overall species composition differed significantly among years and changed serially with year. When abundances were converted to percentage compositions, this pattern of seriation broke down, demonstrating that changes in abundance and not percentage composition were responsible for the seriation. As with the number and abundance of species, changes in composition over the 26 years were not related to any of the physico-chemical/climatic factors tested. Species composition changed monthly in a pronounced cyclical manner throughout the year, due to statistically different time-staggered changes in the abundance of each species. This cyclicity was related most strongly to salinity.

Relating mesocarnivore relative abundance to anthropogenic land-use with a hierarchical spatial count model

USGS Publications Warehouse

Crimmins, Shawn M.; Walleser, Liza R.; Hertel, Dan R.; McKann, Patrick C.; Rohweder, Jason J.; Thogmartin, Wayne E.

2016-01-01

There is growing need to develop models of spatial patterns in animal abundance, yet comparatively few examples of such models exist. This is especially true in situations where the abundance of one species may inhibit that of another, such as the intensively-farmed landscape of the Prairie Pothole Region (PPR) of the central United States, where waterfowl production is largely constrained by mesocarnivore nest predation. We used a hierarchical Bayesian approach to relate the distribution of various land-cover types to the relative abundances of four mesocarnivores in the PPR: coyote Canis latrans, raccoon Procyon lotor, red fox Vulpes vulpes, and striped skunk Mephitis mephitis. We developed models for each species at multiple spatial resolutions (41.4 km2, 10.4 km2, and 2.6 km2) to address different ecological and management-related questions. Model results for each species were similar irrespective of resolution. We found that the amount of row-crop agriculture was nearly ubiquitous in our best models, exhibiting a positive relationship with relative abundance for each species. The amount of native grassland land-cover was positively associated with coyote and raccoon relative abundance, but generally absent from models for red fox and skunk. Red fox and skunk were positively associated with each other, suggesting potential niche overlap. We found no evidence that coyote abundance limited that of other mesocarnivore species, as might be expected under a hypothesis of mesopredator release. The relationships between relative abundance and land-cover types were similar across spatial resolutions. Our results indicated that mesocarnivores in the PPR are most likely to occur in portions of the landscape with large amounts of agricultural land-cover. Further, our results indicated that track-survey data can be used in a hierarchical framework to gain inferences regarding spatial patterns in animal relative abundance.

Abundance and Size of Gulf Shrimp in Louisiana's Coastal Estuaries following the Deepwater Horizon Oil Spill

PubMed Central

van der Ham, Joris L.; de Mutsert, Kim

2014-01-01

The Deepwater Horizon oil spill impacted Louisiana's coastal estuaries physically, chemically, and biologically. To better understand the ecological consequences of this oil spill on Louisiana estuaries, we compared the abundance and size of two Gulf shrimp species (Farfantepeneus aztecus and Litopeneus setiferus) in heavily affected and relatively unaffected estuaries, before and after the oil spill. Two datasets were used to conduct this study: data on shrimp abundance and size before the spill were available from Louisiana Department of Wildlife and Fisheries (LDWF). Data on shrimp abundance and size from after the spill were independently collected by the authors and by LDWF. Using a Before-After-Control-Impact with Paired sampling (BACIP) design with monthly samples of two selected basins, we found brown shrimp to become more abundant and the mean size of white shrimp to become smaller. Using a BACIP with data on successive shrimp year-classes of multiple basins, we found both species to become more abundant in basins that were affected by the spill, while mean shrimp size either not change after the spill, or increased in both affected and unaffected basins. We conclude that following the oil spill abundances of both species increased within affected estuaries, whereas mean size may have been unaffected. We propose two factors that may have caused these results: 1) exposure to polycyclic aromatic hydrocarbons (PAHs) may have reduced the growth rate of shrimp, resulting in a delayed movement of shrimp to offshore habitats, and an increase of within-estuary shrimp abundance, and 2) fishing closures established immediately after the spill, may have resulted in decreased fishing effort and an increase in shrimp abundance. This study accentuates the complexities in determining ecological effects of oil spills, and the need of studies on the organismal level to reveal cause-and-effect relationships of such events. PMID:25272142

Linking nutrient inputs, phytoplankton composition, zooplankton dynamics and the recruitment of pink snapper, Chrysophrys auratus, in a temperate bay

NASA Astrophysics Data System (ADS)

Black, Kerry P.; Longmore, Andrew R.; Hamer, Paul A.; Lee, Randall; Swearer, Stephen E.; Jenkins, Gregory P.

2016-12-01

Survival of larval fish is often linked to production of preferred prey such as copepods, both inter- and intra-annually. In turn, copepod production depends not only the quantity of food, but also on the nutritional quality, edibility and/or toxicity of their micro-algal food. Hence, larval fish survival can become de-coupled from levels of nutrient input depending on the resulting composition of the plankton. Here we use a plankton dynamics model to study nutrient input, phytoplankton composition and copepod, Paracalanus, production in relation to interannual variation in recruitment of snapper, Chrysophrys auratus, in Port Phillip Bay, Australia. The model was able to simulate the ratio of diatoms to flagellates in the plume of the main river entering Port Phillip Bay. Interannual variability in the copepod, Paracalanus, abundance during the C. auratus spawning period over 5 years was accurately predicted. The seasonal peak in Paracalanus production depended on the timing and magnitude (match-mismatch) of nutrient inputs and how these were reflected in temporal change in the diatom:flagellate ratio. In turn, the model-predicted Paracalanus abundance was strongly related to inter-annaul variability in abundance of snapper, C. auratus, larvae over 7 years. Years of highest larval C. auratus abundance coincided with a matching of the spawning period with the peak in Paracalanus abundance. High freshwater flows and nutrient inputs led to an early seasonal dominance of diatoms, and consequently reduced abundances of copepods over the C. auratus spawning period with correspondingly low abundances of larvae. Conversely years of very low rainfall and nutrient input also led to low phytoplankton and copepod concentrations and larval C. auratus abundances. Highest abundances of larval C. auratus occurred in years of low to intermediate rainfall and nutrient inputs, particularly when pulses of nutrients occurred in the spring period, the latter supporting the match-mismatch hypothesis.

Finding a Fox: An Evaluation of Survey Methods to Estimate Abundance of a Small Desert Carnivore

PubMed Central

Dempsey, Steven J.; Gese, Eric M.; Kluever, Bryan M.

2014-01-01

The status of many carnivore species is a growing concern for wildlife agencies, conservation organizations, and the general public. Historically, kit foxes (Vulpes macrotis) were classified as abundant and distributed in the desert and semi-arid regions of southwestern North America, but is now considered rare throughout its range. Survey methods have been evaluated for kit foxes, but often in populations where abundance is high and there is little consensus on which technique is best to monitor abundance. We conducted a 2-year study to evaluate four survey methods (scat deposition surveys, scent station surveys, spotlight survey, and trapping) for detecting kit foxes and measuring fox abundance. We determined the probability of detection for each method, and examined the correlation between the relative abundance as estimated by each survey method and the known minimum kit fox abundance as determined by radio-collared animals. All surveys were conducted on 15 5-km transects during the 3 biological seasons of the kit fox. Scat deposition surveys had both the highest detection probabilities (p = 0.88) and were most closely related to minimum known fox abundance (r2 = 0.50, P = 0.001). The next best method for kit fox detection was the scent station survey (p = 0.73), which had the second highest correlation to fox abundance (r2 = 0.46, P<0.001). For detecting kit foxes in a low density population we suggest using scat deposition transects during the breeding season. Scat deposition surveys have low costs, resilience to weather, low labor requirements, and pose no risk to the study animals. The breeding season was ideal for monitoring kit fox population size, as detections consisted of the resident population and had the highest detection probabilities. Using appropriate monitoring techniques will be critical for future conservation actions for this rare desert carnivore. PMID:25148102

Controls of picophytoplankton abundance and composition in a highly dynamic marine system, the Northern Alboran Sea (Western Mediterranean)

NASA Astrophysics Data System (ADS)

Amorim, Ana L.; León, Pablo; Mercado, Jesús M.; Cortés, Dolores; Gómez, Francisco; Putzeys, Sebastien; Salles, Soluna; Yebra, Lidia

2016-06-01

The Alboran Sea is a highly dynamic basin which exhibits a high spatio-temporal variability of hydrographic structures (e.g. fronts, gyres, coastal upwellings). This work compares the abundance and composition of picophytoplankton observed across the northern Alboran Sea among eleven cruises between 2008 and 2012 using flow cytometry. We evaluate the seasonal and longitudinal variability of picophytoplankton on the basis of the circulation regimes at a regional scale and explore the presence of cyanobacteria ecotypes in the basin. The maximal abundances obtained for Prochlorococcus, Synechococcus and picoeukaryotes (12.7 × 104, 13.9 × 104 and 8.6 × 104 cells mL- 1 respectively) were consistent with those reported for other adjacent marine areas. Seasonal changes in the abundance of the three picophytoplankton groups were highly significant although they did not match the patterns described for other coastal waters. Higher abundances of Prochlorococcus were obtained in autumn-winter while Synechococcus and picoeukaryotes exhibited a different seasonal abundance pattern depending on the sector (e.g. Synechococcus showed higher abundance in summer in the west sector and during winter in the eastern study area). Additionally, conspicuous longitudinal gradients were observed for Prochlorococcus and Synechococcus, with Prochlorococcus decreasing from west to east and Synechococcus following the opposite pattern. The analysis of environmental variables (i.e. temperature, salinity and inorganic nutrients) and cell abundances indicates that Prochlorococcus preferred high salinity and nitrate to phosphate ratio. On the contrary, temperature did not seem to play a role in Prochlorococcus distribution as it was numerically important during the whole seasonal cycle. Variability in Synechococcus abundance could not be explained by changes in any environmental variable suggesting that different ecotypes were sampled during the surveys. In particular, our data would indicate the presence of at least two ecotypes of Synechococcus: a summer ecotype widely distributed in the whole Alboran Sea and a winter ecotype adapted to lower temperature and higher nutrient concentration whose growth is favoured in the eastern sector.

An Analysis of Thaumarchaeota Populations from the Northern Gulf of Mexico

PubMed Central

Tolar, Bradley B.; King, Gary M.; Hollibaugh, James T.

2013-01-01

We sampled Thaumarchaeota populations in the northern Gulf of Mexico, including shelf waters under the Mississippi River outflow plume that are subject to recurrent hypoxia. Data from this study allowed us to: (1) test the hypothesis that Thaumarchaeota would be abundant in this region; (2) assess phylogenetic composition of these populations for comparison with other regions; (3) compare the efficacy of quantitative PCR (qPCR) based on primers for 16S rRNA genes (rrs) with primers for genes in the ammonia oxidation (amoA) and carbon fixation (accA, hcd) pathways; (4) compare distributions obtained by qPCR with the relative abundance of Thaumarchaeota rrs in pyrosequenced libraries; (5) compare Thaumarchaeota distributions with environmental variables to help us elucidate the factors responsible for the distributions; (6) compare the distribution of Thaumarchaeota with Nitrite-Oxidizing Bacteria (NOB) to gain insight into the coupling between ammonia and nitrite oxidation. We found up to 108 copies L−1 of Thaumarchaeota rrs in our samples (up to 40% of prokaryotes) by qPCR, with maximum abundance in slope waters at 200–800 m. Thaumarchaeota rrs were also abundant in pyrosequenced libraries and their relative abundance correlated well with values determined by qPCR (r2 = 0.82). Thaumarchaeota populations were strongly stratified by depth. Canonical correspondence analysis using a suite of environmental variables explained 92% of the variance in qPCR-estimated gene abundances. Thaumarchaeota rrs abundance was correlated with salinity and depth, while accA abundance correlated with fluorescence and pH. Correlations of Archaeal amoA abundance with environmental variables were primer-dependent, suggesting differential responses of sub-populations to environmental variables. Bacterial amoA was at the limit of qPCR detection in most samples. NOB and Euryarchaeota rrs were found in the pyrosequenced libraries; NOB distribution was correlated with that of Thaumarchaeota (r2 = 0.49). PMID:23577005

Microbial signatures of oral dysbiosis, periodontitis and edentulism revealed by Gene Meter methodology.

PubMed

Hunter, M Colby; Pozhitkov, Alex E; Noble, Peter A

2016-12-01

Conceptual models suggest that certain microorganisms (e.g., the "red" complex) are indicative of a specific disease state (e.g., periodontitis); however, recent studies have questioned the validity of these models. Here, the abundances of 500+ microbial species were determined in 16 patients with clinical signs of one of the following oral conditions: periodontitis, established caries, edentulism, and oral health. Our goal was to determine if the abundances of certain microorganisms reflect dysbiosis or a specific clinical condition that could be used as a 'signature' for dental research. Microbial abundances were determined by the analysis of 138,718 calibrated probes using Gene Meter methodology. Each 16S rRNA gene was targeted by an average of 194 unique probes (n=25nt). The calibration involved diluting pooled gene target samples, hybridizing each dilution to a DNA microarray, and fitting the probe intensities to adsorption models. The fit of the model to the experimental data was used to assess individual and aggregate probe behavior; good fits (R 2 >0.90) were retained for back-calculating microbial abundances from patient samples. The abundance of a gene was determined from the median of all calibrated individual probes or from the calibrated abundance of all aggregated probes. With the exception of genes with low abundances (<2 arbitrary units), the abundances determined by the different calibrations were highly correlated (r~1.0). Seventeen genera were classified as 'signatures of dysbiosis' because they had significantly higher abundances in patients with periodontitis and edentulism when contrasted with health. Similarly, 13 genera were classified as 'signatures of periodontitis', and 14 genera were classified as 'signatures of edentulism'. The signatures could be used, individually or in combination, to assess the clinical status of a patient (e.g., evaluating treatments such as antibiotic therapies). Comparisons of the same patient samples revealed high false negatives (45%) for next-generation-sequencing results and low false positives (7%) for Gene Meter results. Copyright © 2016 Elsevier B.V. All rights reserved.

New CNO Elemental Abundances in Planetary Nebulae from Spatially Resolved UV/Optical Emission Lines

NASA Astrophysics Data System (ADS)

Shaw, Richard A.; Kwitter, Karen B.; Henry, Richard B. C.; Dufour, Reginald J.; Balick, Bruce; Corradi, Romano

2015-01-01

We obtained HST/STIS long-slit spectra spanning 0.11 to 1.1 μm of co-spatial regions in 10 Galactic planetary nebulae (Dufour, et al., this conference), of which six present substantial changes in ionization with position. Under the assumption that elemental abundances are constant within these nebulae (but exterior to the wind of the central star), these spectra present a unique opportunity to examine the applicability of common ionization correction factors (ICFs) for deriving abundances. ICFs are the most common direct method in abundance analysis for accounting for unobserved or undetected ionization stages in nebulae, yet most ICF recipes have not been rigorously examined through modeling nor empirically tested through observation. In this preliminary study, we focussed on the astrophysically important abundances of C and N where strong ionic transitions are scarce in optical band, but plentiful in the satellite UV. We derived physical diagnostics (extinction, Te, Ne) and ionic abundances for the species of interest at various positions along the slit for each PN. We compared the elemental abundances derived from direct summation of the ionic abundances in the UV and optical to those derived using only optical emission, but corrected using standard ICFs. We found that the abundances were usually in good agreement, but there were significant exceptions. We also found that setting upper limits on emission from undetected ions was sometimes helpful in constraining the correction factors. Work is underway to construct photoionization models of these nebulae (see Miller, et al., this conference) to address the question of why ICFs are sometimes inaccurate, and to explore other ICF recipes for those cases.Support for Program number GO-12600 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

Oxygen abundance in metal-poor dwarfs, derived from the forbidden line

NASA Astrophysics Data System (ADS)

Spite, M.; Spite, F.

1991-12-01

The oxygen abundance is redetermined in a few metal-poor dwarfs, using the oxygen forbidden line at 630 nm rather than the oxygen triplet at 777 nm previously used by Abia and Rebolo (1989). The ratios form O/Fe are clearly lower than the previous ones and are in agreement with the ratios found in the metal-poor red giants, suggesting that no real difference exists between dwarfs and giants. Finally, it can be argued that, pending the acquisition of additional information, the oxygen abundances derived from the forbidden line are more reliable than the abundances found from the triplet.

Phosphorus Chemistry in the Atmosphere of Jupiter: A Reassessment

NASA Astrophysics Data System (ADS)

Borunov, Sergei; Dorofeeva, Vera; Khodakovsky, Igor; Drossart, Pierre; Lellouch, Emmanuel; Encrenaz, Thérèse

1995-02-01

A new distribution of phosphorus compounds in the atmosphere of Jupiter is given, using revised values for the chemical constants. In contrast with previous works, it is shown that phosphine PH 3 remains the most abundant equilibrium gaseous compound even at the upper levels of Jupiter's troposphere. The observed PH 3 abundance is equal to the equilibrium value, at all temperatures above 535 K for solar P and O elemental abundances, and above 600 K for a reasonable range of P and O abundances. P 4O 6 does not take part in the phosphorus cycle on Jupiter.

Parametric scaling from species relative abundances to absolute abundances in the computation of biological diversity: a first proposal using Shannon's entropy.

PubMed

Ricotta, Carlo

2003-01-01

Traditional diversity measures such as the Shannon entropy are generally computed from the species' relative abundance vector of a given community to the exclusion of species' absolute abundances. In this paper, I first mention some examples where the total information content associated with a given community may be more adequate than Shannon's average information content for a better understanding of ecosystem functioning. Next, I propose a parametric measure of statistical information that contains both Shannon's entropy and total information content as special cases of this more general function.

Population interactions among free-living bluefish and prey fish in an ocean environment.

PubMed

Safina, Carl; Burger, Joanna

1989-04-01

We used sonar to measure relative abundance, location, and depth of prey fish schools (primarily Anchoa and Ammodytes) in the ocean near Fire Island Inlet, New York from May to August for 4 years to examine predatorprey interactions. Prey fish numbers built through May, peaked in June, and thereafter declined coincident with the arrival of predatory bluefish. Bluefish abundance and feeding behavior correlated inversely with prey fish abundance and depth. Bluefish may drive seasonal patterns of prey abundance and distribution in this area through direct predation and by causing prey to flee.

Data on the abundance of the banana weevil Cosmopolites sordidus and of the earwig Euborellia caraibea in bare soil and cover crop plots

PubMed Central

Carval, Dominique; Resmond, Rémi; Achard, Raphaël; Tixier, Philippe

2016-01-01

The data presented in this article are related to the research article entitled “Cover cropping reduces the abundance of the banana weevil Cosmopolites sordidus but does not reduce its damage to the banana plants” (Carval et al., in press) [1]. This article describes how the abundance of the banana weevil, Cosmopolites sordidus, and the abundance of the earwig Euborellia caraibea were affected by the addition of a cover crop. The field data set is made publicly available to enable critical or extended analyzes. PMID:27222854

Data on the abundance of the banana weevil Cosmopolites sordidus and of the earwig Euborellia caraibea in bare soil and cover crop plots.

PubMed

Carval, Dominique; Resmond, Rémi; Achard, Raphaël; Tixier, Philippe

2016-06-01

The data presented in this article are related to the research article entitled "Cover cropping reduces the abundance of the banana weevil Cosmopolites sordidus but does not reduce its damage to the banana plants" (Carval et al., in press) [1]. This article describes how the abundance of the banana weevil, Cosmopolites sordidus, and the abundance of the earwig Euborellia caraibea were affected by the addition of a cover crop. The field data set is made publicly available to enable critical or extended analyzes.

Hyperfine Structure and Abundances of Heavy Elements in 68 Tauri (HD 27962)

NASA Astrophysics Data System (ADS)

Martinet, S.; Monier, R.

2017-12-01

HD 27962, also known as 68 Tauri, is a Chemically Peculiar Am star member of the Hyades Open Cluster in the local arm of the Galaxy. We have modeled the high resolution SOPHIE (R=75000) spectrum of 68 Tauri using updated model atmosphere and spectrum synthesis to derive chemical abundances in its atmosphere. In particular, we have studied the effect of the inclusion of Hyperfine Structure of various Baryum isotopes on the determination of the Baryum abundance in 68 Tauri. We have also derived new abundances using updated accurate atomic parameters retrieved from the NIST database.

Elemental abundance differences between nuclei acclerated in CIR shocks and solar flares

NASA Technical Reports Server (NTRS)

Dietrich, W. F.; Simpson, J. A.

1985-01-01

Measurement of the ratios of nuclear abundances H/He, CNO/Fe-group and the Fe-group/HE for 51 passages of Corotating Interaction Regions (CIRs) at 1 AU, and measurement of these ratios from 620 solar flares in the energy range 0.6 to 4 MeV per nucleon, show that CIR shock acceleration alone does not change significantly these ratios from the values they have for solar system abundances or the solar wind. The solar flare ratios continue to reflect strong biases in the abundances, consistent with requirements for multistage acceleration rpocesses at the Sun.

Dust formation in a galaxy with primitive abundances.

PubMed

Sloan, G C; Matsuura, M; Zijlstra, A A; Lagadec, E; Groenewegen, M A T; Wood, P R; Szyszka, C; Bernard-Salas, J; van Loon, J Th

2009-01-16

Interstellar dust plays a crucial role in the evolution of galaxies. It governs the chemistry and physics of the interstellar medium. In the local universe, dust forms primarily in the ejecta from stars, but its composition and origin in galaxies at very early times remain controversial. We report observational evidence of dust forming around a carbon star in a nearby galaxy with a low abundance of heavy elements, 25 times lower than the solar abundance. The production of dust by a carbon star in a galaxy with such primitive abundances raises the possibility that carbon stars contributed carbonaceous dust in the early universe.

Reproducibility of combinatorial peptide ligand libraries for proteome capture evaluated by selected reaction monitoring.

PubMed

Di Girolamo, Francesco; Righetti, Pier Giorgio; Soste, Martin; Feng, Yuehan; Picotti, Paola

2013-08-26

Systems biology studies require the capability to quantify with high precision proteins spanning a broad range of abundances across multiple samples. However, the broad range of protein expression in cells often precludes the detection of low-abundance proteins. Different sample processing techniques can be applied to increase proteome coverage. Among these, combinatorial (hexa)peptide ligand libraries (CPLLs) bound to solid matrices have been used to specifically capture and detect low-abundance proteins in complex samples. To assess whether CPLL capture can be applied in systems biology studies involving the precise quantitation of proteins across a multitude of samples, we evaluated its performance across the whole range of protein abundances in Saccharomyces cerevisiae. We used selected reaction monitoring assays for a set of target proteins covering a broad abundance range to quantitatively evaluate the precision of the approach and its capability to detect low-abundance proteins. Replicated CPLL-isolates showed an average variability of ~10% in the amount of the isolated proteins. The high reproducibility of the technique was not dependent on the abundance of the protein or the amount of beads used for the capture. However, the protein-to-bead ratio affected the enrichment of specific proteins. We did not observe a normalization effect of CPLL beads on protein abundances. However, CPLLs enriched for and depleted specific sets of proteins and thus changed the abundances of proteins from a whole proteome extract. This allowed the identification of ~400 proteins otherwise undetected in an untreated sample, under the experimental conditions used. CPLL capture is thus a useful tool to increase protein identifications in proteomic experiments, but it should be coupled to the analysis of untreated samples, to maximize proteome coverage. Our data also confirms that CPLL capture is reproducible and can be confidently used in quantitative proteomic experiments. Combinatorial hexapeptide ligand libraries (CPLLs) bound to solid matrices have been proposed to specifically capture and detect low-abundance proteins in complex samples. To assess whether the CPLL capture can be confidently applied in systems biology studies involving the precise quantitation of proteins across a broad range of abundances and a multitude of samples, we evaluated its reproducibility and performance features. Using selected reaction monitoring assays for proteins covering the whole range of abundances we show that the technique is reproducible and compatible with quantitative proteomic studies. However, the protein-to-bead ratio affects the enrichment of specific proteins and CPLLs depleted specific sets of proteins from a whole proteome extract. Our results suggest that CPLL-based analyses should be coupled to the analysis of untreated samples, to maximize proteome coverage. Overall, our data confirms the applicability of CPLLs in systems biology research and guides the correct use of this technique. Copyright © 2013 Elsevier B.V. All rights reserved.

Unexpectedly higher metazoan meiofauna abundances in the Kuril-Kamchatka Trench compared to the adjacent abyssal plains

NASA Astrophysics Data System (ADS)

Schmidt, Christina; Martínez Arbizu, Pedro

2015-01-01

We studied meiofauna standing stocks and community structure in the Kuril-Kamchatka Trench and its adjacent abyssal plains in the northwestern Pacific Ocean. In general, the Nematoda were dominant (93%) followed by the Copepoda (4%). Nematode abundances ranged from 87% to 96%; those of copepods from 2% to 7%. The most diverse deployment yielded 17 taxa: Acari, Amphipoda, Annelida, Bivalvia, Coelenterata, Copepoda, Cumacea, Gastrotricha, Isopoda, Kinorhyncha, Loricifera, Nematoda, Ostracoda, Priapulida, Tanaidacea, Tantulocarida, and Tardigrada. Nauplii were also present. Generally, the trench slope and the southernmost deployments had the highest abundances (850-1392 individuals/cm2). The results of non-metric multidimensional scaling indicated that these deployments were similar to each other in meiofauna community structure. The southernmost deployments were located in a zone of higher particulate organic carbon (POC) flux (g Corg m-2 yr-1), whereas the trench slope should have low POC flux due to depth attenuation. Also, POC and abundance were significantly correlated in the abyssal plains. This correlation may explain the higher abundances at the southernmost deployments. Lateral transport was also assumed to explain high meiofauna abundances on the trench slope. Abundances were generally higher than expected from model results. ANOSIM revealed significant differences between the trench slope and the northern abyssal plains, between the central abyssal plains and the trench slope, between the trench slope and the southern abyssal plains, between the central and the southern abyssal plains, and between the central and northern deployments. The northern and southern abyssal plains did not differ significantly. In addition, a U-test revealed highly significant differences between the trench-slope and abyssal deployments. The taxa inhabited mostly the upper 0-3 cm of the sediment layer (Nematoda 80-90%; Copepoda 88-100%). The trench-slope and abyssal did not differ in occupancy of the top layer. Furthermore, sediment depth and abundance were strongly correlated, but the sediment texture itself and the grain sizes showed only slight correlations with abundance. In the trench slope no correlation between sediment texture and abundance was found. We suggest that sediment is not the only factor that affects meiofauna abundance in the study area. The results of our study were compared with other trench and nontrench studies, and in most cases, the abundance decreases with depth initially but increases again below a certain depth, especially in deep-sea trenches below productive waters. No generalization can be made, however, about the depth at which the reversal occurs; it depends on the area of investigation and on a mixture of many other factors (e.g., sediment heterogeneity, oxygen, redox potential, proximity to land masses, and season).

The evolution of the lithium abundances of solar-type stars. II - The Ursa Major Group

NASA Technical Reports Server (NTRS)

Soderblom, David R.; Pilachowski, Catherine A.; Fedele, Stephen B.; Jones, Burton F.

1993-01-01

We draw upon a recent study of the membership of the Ursa Major Group (UMaG) to examine lithium among 0.3 Gyr old solar-type stars. For most G and K dwarfs, Li confirms the conclusions about membership in UMaG reached on the basis of kinematics and chromospheric activity. G and K dwarfs in UMaG have less Li than comparable stars in the Pleiades. This indicates that G and K dwarfs undergo Li depletion while they are on the main sequence, in addition to any pre-main-sequence depletion they may have experienced. Moreover, the Li abundances of the Pleiades K dwarfs cannot be attributed to main-sequence depletion alone, demonstrating that pre-main-sequence depletion of Li also takes place. The sun's Li abundance implies that the main-sequence mechanism becomes less effective with age. The hottest stars in UMaG have Li abundances like those of hot stars in the Pleiades and Hyades and in T Tauris, and the two genuine UMaG members with temperatures near Boesgaard's Li chasm have Li abundances consistent with that chasm developing fully by 0.3 Gyr for stars with UMaG's metallicity. We see differences in the abundance of Li between UMaG members of the same spectral types, indicating that a real spread in the lithium abundance exists within this group.

Dynamic regulation of partner abundance mediates response of reef coral symbioses to environmental change.

PubMed

Cunning, R; Vaughan, N; Gillette, P; Capo, T R; Matté, J L; Baker, A C

2015-05-01

Regulating partner abunclance may allow symmotic organisms to mediate interaction outcomes, facilitating adaptive responses to environmental change. To explore the capacity for-adaptive regulation in an ecologically important endosymbiosis, we studied the population dynamics of symbiotic algae in reef-building corals under different abiotic contexts. We found high natural variability in symbiont abundance in corals across reefs, but this variability converged to different symbiont-specific abundances when colonies were maintained under constant conditions. When conditions changed seasonally, symbiont abundance readjusted to new equilibria. We explain these patterns using an a priori model of symbiotic costs and benefits to the coral host, which shows that the observed changes in symbiont abundance are consistent with the maximization of interaction benefit under different environmental conditions. These results indicate that, while regulating symbiont abundance helps hosts sustain maximum benefit in a dynamic environment, spatiotemporal variation in abiotic factors creates a broad range of symbiont abundances (and interaction outcomes) among corals that may account for observed natural variability in performance (e.g., growth rate) and stress tolerance (e.g., bleaching susceptibility). This cost or benefit framework provides a new perspective on the dynamic regulation of reef coral symbioses and illustrates that the dependence of interaction outcomes on biotic and abiotic contexts may be important in understanding how diverse mutualisms respond to environmental change.

Differential protein abundance of a basolateral MCT1 transporter in the human gastrointestinal tract.

PubMed

Al-Mosauwi, Hashemeya; Ryan, Elizabeth; McGrane, Alison; Riveros-Beltran, Stefanie; Walpole, Caragh; Dempsey, Eugene; Courtney, Danielle; Fearon, Naomi; Winter, Desmond; Baird, Alan; Stewart, Gavin

2016-12-01

Bacterially derived short chain fatty acids (SCFAs), such as butyrate, are vital in maintaining the symbiotic relationship that exists between humans and their gastrointestinal microbial populations. A key step in this process is the transport of SCFAs across colonic epithelial cells via MCT1 transporters. This study investigated MCT1 protein abundance in various human intestinal tissues. Initial RT-PCR analysis confirmed the expected MCT1 RNA expression pattern of colon > small intestine > stomach. Using surgical resection samples, immunoblot analysis detected higher abundance of a 45 kDa MCT1 protein in colonic tissue compared to ileum tissue (P < 0.001, N = 4, unpaired t-test). Importantly, MCT1 abundance was found to be significantly lower in sigmoid colon compared to ascending colon (P < 0.01, N = 8-11, ANOVA). Finally, immunolocalization studies confirmed MCT1 to be abundant in the basolateral membranes of surface epithelial cells of the ascending, transverse, and descending colon, but significantly less prevalent in the sigmoid colon (P < 0.05, N = 5-21, ANOVA). In conclusion, these data confirm that basolateral MCT1 protein abundance is correlated to levels of bacterially derived SCFAs along the human gastrointestinal tract. These findings highlight the importance of precise tissue location in studies comparing colonic MCT1 abundance between normal and diseased states. © 2016 International Federation for Cell Biology.

Global abundance of planktonic heterotrophic protists in the deep ocean

PubMed Central

Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon

2015-01-01

The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml−1 in mesopelagic waters down to 11±1 cells ml−1 in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml−1. The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web. PMID:25290506

Fungal decomposers of leaf litter from an invaded and native mountain forest of NW Argentina.

PubMed

Fernandez, Romina Daiana; Bulacio, Natalia; Álvarez, Analía; Pajot, Hipólito; Aragón, Roxana

2017-09-01

The impact of plant species invasions on the abundance, composition and activity of fungal decomposers of leaf litter is poorly understood. In this study, we isolated and compared the relative abundance of ligninocellulolytic fungi of leaf litter mixtures from a native forest and a forest invaded by Ligustrum lucidum in a lower mountain forest of Tucuman, Argentina. In addition, we evaluated the relationship between the relative abundance of ligninocellulolytic fungi and properties of the soil of both forest types. Finally, we identified lignin degrading fungi and characterized their polyphenol oxidase activities. The relative abundance of ligninocellulolytic fungi was higher in leaf litter mixtures from the native forest. The abundance of cellulolytic fungi was negatively related with soil pH while the abundance of ligninolytic fungi was positively related with soil humidity. We identified fifteen genera of ligninolytic fungi; four strains were isolated from both forest types, six strains only from the invaded forest and five strains were isolated only from the native forest. The results found in this study suggest that L. Lucidum invasion could alter the abundance and composition of fungal decomposers. Long-term studies that include an analysis of the nutritional quality of litter are needed, for a more complete overview of the influence of L. Lucidum invasion on fungal decomposers and on leaf litter decomposition.

A method for estimating abundance of mobile populations using telemetry and counts of unmarked animals

USGS Publications Warehouse

Clement, Matthew; O'Keefe, Joy M; Walters, Brianne

2015-01-01

While numerous methods exist for estimating abundance when detection is imperfect, these methods may not be appropriate due to logistical difficulties or unrealistic assumptions. In particular, if highly mobile taxa are frequently absent from survey locations, methods that estimate a probability of detection conditional on presence will generate biased abundance estimates. Here, we propose a new estimator for estimating abundance of mobile populations using telemetry and counts of unmarked animals. The estimator assumes that the target population conforms to a fission-fusion grouping pattern, in which the population is divided into groups that frequently change in size and composition. If assumptions are met, it is not necessary to locate all groups in the population to estimate abundance. We derive an estimator, perform a simulation study, conduct a power analysis, and apply the method to field data. The simulation study confirmed that our estimator is asymptotically unbiased with low bias, narrow confidence intervals, and good coverage, given a modest survey effort. The power analysis provided initial guidance on survey effort. When applied to small data sets obtained by radio-tracking Indiana bats, abundance estimates were reasonable, although imprecise. The proposed method has the potential to improve abundance estimates for mobile species that have a fission-fusion social structure, such as Indiana bats, because it does not condition detection on presence at survey locations and because it avoids certain restrictive assumptions.

Landscape surrounding human settlements and Anopheles albimanus (Diptera: Culicidae) abundance in Southern Chiapas, Mexico.

PubMed

Rodriguez, A D; Rodriguez, M H; Hernandez, J E; Dister, S W; Beck, L R; Rejmankova, E; Roberts, D R

1996-01-01

Landscape characteristics that may influence important components of the Anopheles albimanus Wiedemann life cycle, including potential breeding sites, suitable diurnal resting sites, and possible sources of blood meals, were analyzed at 14 villages in a malarious area of southern Mexico. An. albimanus adults were collected weekly in each village using UV-light traps between July 1991 and August 1992. Based on rainfall, the study was divided into 6 seasonal periods. Villages were considered to have high mosquito abundance when >5 mosquitoes per trap per night were collected during any 1 of the 6 seasonal periods. The extension and frequency of 11 land cover types surrounding villages were determined using aerial photographs and subsequently verified through field surveys. Elevation was the main landscape feature that separated villages with low and high mosquito abundance. All villages with high mosquito abundance were below 25 m. Transitional and mangrove land cover types were found only in the high mosquito abundance group. Flooded areas as potential breeding sites and potential adult resting sites in unmanaged pastures were significantly more frequent in areas surrounding villages with high mosquito abundance. No significant differences in density of cattle and horses were found among village groups. Overall, surrounding breeding sites located at low elevations in flooded unmanaged pastures seemed to be the most important determinants of An. albimanus adult abundance in the villages.

Factors affecting abundance and prevalence of blood fluke, Cardicola forsteri, infection in commercially ranched southern bluefin tuna, Thunnus maccoyii, in Australia.

PubMed

Aiken, Hamish M; Hayward, Craig J; Nowak, Barbara F

2015-05-30

A survey of blood fluke, Cardicola forsteri, infection in ranched southern bluefin tuna, Thunnus maccoyii, was undertaken over three farming seasons, from March 2004 to September 2006. Analyses of covariance and logistic regression were used to explore the effects of company, year, season, time in culture, and condition index on intensity, abundance and prevalence of blood fluke infection. Average prevalence of blood fluke infection was 62.64% over the period of the survey. Average intensity was 6.20 (± 0.57) fluke per infected host and the average abundance was 3.70 (± 0.57) fluke per host. Year did not influence mean intensity or abundance although a significant decrease in prevalence in 2005 was evident. Tuna harvested in winter had a significantly greater abundance and prevalence of blood fluke than the tuna harvested in autumn. No effect of intensity or abundance of infection was observed on the condition of the infected tuna. A universal factor in explaining variation in C. forsteri intensity, abundance and prevalence was company. Differences in infection levels between tuna from different companies may be related to differences in husbandry measures employed on each farm, or due to different average sizes of tuna farmed by each of the companies, or due to the location of the operations. Copyright © 2015 Elsevier B.V. All rights reserved.

Identifying the key taxonomic categories that characterize microbial community diversity using full-scale classification: a case study of microbial communities in the sediments of Hangzhou Bay.

PubMed

Dai, Tianjiao; Zhang, Yan; Tang, Yushi; Bai, Yaohui; Tao, Yile; Huang, Bei; Wen, Donghui

2016-10-01

Coastal areas are land-sea transitional zones with complex natural and anthropogenic disturbances. Microorganisms in coastal sediments adapt to such disturbances both individually and as a community. The microbial community structure changes spatially and temporally under environmental stress. In this study, we investigated the microbial community structure in the sediments of Hangzhou Bay, a seriously polluted bay in China. In order to identify the roles and contribution of all microbial taxa, we set thresholds as 0.1% for rare taxa and 1% for abundant taxa, and classified all operational taxonomic units into six exclusive categories based on their abundance. The results showed that the key taxa in differentiating the communities are abundant taxa (AT), conditionally abundant taxa (CAT), and conditionally rare or abundant taxa (CRAT). A large population in conditionally rare taxa (CRT) made this category collectively significant in differentiating the communities. Both bacteria and archaea demonstrated a distance decay pattern of community similarity in the bay, and this pattern was strengthened by rare taxa, CRT and CRAT, but weakened by AT and CAT. This implied that the low abundance taxa were more deterministically distributed, while the high abundance taxa were more ubiquitously distributed. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A fast fully constrained geometric unmixing of hyperspectral images

NASA Astrophysics Data System (ADS)

Zhou, Xin; Li, Xiao-run; Cui, Jian-tao; Zhao, Liao-ying; Zheng, Jun-peng

2014-11-01

A great challenge in hyperspectral image analysis is decomposing a mixed pixel into a collection of endmembers and their corresponding abundance fractions. This paper presents an improved implementation of Barycentric Coordinate approach to unmix hyperspectral images, integrating with the Most-Negative Remove Projection method to meet the abundance sum-to-one constraint (ASC) and abundance non-negativity constraint (ANC). The original barycentric coordinate approach interprets the endmember unmixing problem as a simplex volume ratio problem, which is solved by calculate the determinants of two augmented matrix. One consists of all the members and the other consist of the to-be-unmixed pixel and all the endmembers except for the one corresponding to the specific abundance that is to be estimated. In this paper, we first modified the algorithm of Barycentric Coordinate approach by bringing in the Matrix Determinant Lemma to simplify the unmixing process, which makes the calculation only contains linear matrix and vector operations. So, the matrix determinant calculation of every pixel, as the original algorithm did, is avoided. By the end of this step, the estimated abundance meet the ASC constraint. Then, the Most-Negative Remove Projection method is used to make the abundance fractions meet the full constraints. This algorithm is demonstrated both on synthetic and real images. The resulting algorithm yields the abundance maps that are similar to those obtained by FCLS, while the runtime is outperformed as its computational simplicity.

Spatial Variations of Chemical Abundances in Titan's Atmosphere as Revealed by ALMA

NASA Astrophysics Data System (ADS)

Thelen, Alexander E.; Nixon, Conor; Chanover, Nancy J.; Molter, Edward; Serigano, Joseph; Cordiner, Martin; Charnley, Steven B.; Teanby, Nicholas A.; Irwin, Patrick

2016-10-01

Complex organic molecules in Titan's atmosphere - formed through the dissociation of N2 and CH4 - exhibit latitudinal variations in abundance as observed by Cassini. Chemical species including hydrocarbons - such as CH3CCH - and nitriles - HCN, HC3N, CH3CN, and C2H5CN - may show spatial abundance variations as a result of atmospheric circulation, photochemical production and subsequent destruction throughout Titan's seasonal cycle. Recent calibration images of Titan taken by the Atacama Large Millimeter/Submillimeter Array (ALMA) with beam sizes of ~0.3'' allow for measurements of rotational transition lines of these species in spatially resolved regions of Titan's disk. We present abundance profiles obtained from public ALMA data taken in 2014, as Titan transitioned into northern summer. Abundance profiles in Titan's lower/middle atmosphere were retrieved by modeling high resolution ALMA spectra using the Non-linear Optimal Estimator for MultivariatE Spectral analySIS (NEMESIS) radiative transfer code. These retrievals were performed using spatial temperature profiles obtained by modeling strong CO lines from datasets taken in similar times with comparable resolution. We compare the abundance variations of chemical species to measurements made using Cassini data. Comparisons of chemical species with strong abundance enhancements over the poles will inform our knowledge of chemical lifetimes in Titan's atmosphere, and allow us to observe the important changes in production and circulation of numerous organic molecules which are attributed to Titan's seasons.

Impact of eutrophication on shallow marine benthic foraminifers over the last 150 years in Osaka Bay, Japan

USGS Publications Warehouse

Tsujimoto, Akira; Nomura, Ritsuo; Yasuhara, Moriaki; Yamazaki, Hideo; Yoshikawa, Shusaku

2006-01-01

High-resolution foraminiferal analysis was conducted on a short sediment core from the inner part of Osaka Bay, Japan. Changes in foraminiferal assemblages were associated with eutrophication, bottom water hypoxia, and changes in red tide-causing algae. Before the 1920s, the calcareous species Ammonia beccarii, and the agglutinated species Eggerella advena and Trochammina hadai were rare, but calcareous foraminifers in general were abundant. Between the 1920s and 1940s, calcareous foraminifers decreased abruptly in abundance, while A. beccarii, E. advena and T. hadai increased in abundance. This faunal change corresponded in time to an increase in nutrients flowing in through the Yodo River, and bottom water hypoxia related to eutrophication. In the 1960s and 1970s, A. beccarii, E. advena and T. hadai further increased in abundance to become dominant, and many calcareous foraminifers nearly disappeared, corresponding to increasing bottom water hypoxia related to the rapid increase in discharged nutrients during the high economic growth period from 1953 to 1971. After the 1990s, A. beccarii decreased rapidly in abundance and E. advena and Uvigerinella glabra increased in abundance. The main components of red tide-causing algae changed from dinoflagellates to diatoms in the 1980s through 1990s, thus there was a change in the food supply to the benthos, which may have caused the increase in abundance of E. advena and U. glabra.

Shorebird stopover habitat decisions in a changing landscape

USGS Publications Warehouse

Gillespie, Caitlyn R.; Fontaine, Joseph J.

2017-01-01

To examine how habitat use by sandpipers (Calidris spp.; Baird's sandpipers, dunlin, least sandpipers, pectoral sandpipers, semipalmated sandpipers, stilt sandpipers, and white-rumped sandpipers) varies across a broad suite of environmental conditions, we conducted surveys at wetlands throughout the spring migratory period in 2013 and 2014 in 2 important stopover regions: the Rainwater Basin (RWB) in Nebraska, USA, and the Prairie Pothole Region (PPR) in South Dakota, USA. Because providing adequate energetic resources for migratory birds is a high priority for wetland management, we also measured invertebrate abundance at managed wetlands in the RWB to determine how food abundance influences the occupancy and abundance of sandpipers on wetlands throughout the migratory period. To quantify habitat use, we surveyed wetlands every 7–10 days in both regions and visually estimated wetland attributes. Our results indicate that invertebrate abundance predicted occupancy, but not abundance, of sandpipers at wetlands in the RWB. The wetland vegetation characteristics that predict sandpiper occupancy are similar in both regions, but wetlands in the PPR support a higher abundance of sandpipers than wetlands in the RWB. Our results suggest that sandpipers make stopover decisions that balance local and regional wetland conditions. Managers should maintain the cues (i.e., mudflat) and ecological conditions beyond invertebrate abundance that predict sandpiper habitat use to successfully provide resources for sandpipers during migratory stopover if that is a goal of wetland management. © 2017 The Wildlife Society.

Spider Communities and Biological Control in Native Habitats Surrounding Greenhouses.

PubMed

Cotes, Belén; González, Mónica; Benítez, Emilio; De Mas, Eva; Clemente-Orta, Gemma; Campos, Mercedes; Rodríguez, Estefanía

2018-03-14

The promotion of native vegetation as a habitat for natural enemies, which could increase their abundance and fitness, is especially useful in highly simplified settings such as Mediterranean greenhouse landscapes. Spiders as generalist predators may also be involved in intra-guild predation. However, the niche complementarity provided by spiders as a group means that increased spider diversity may facilitate complementary control actions. In this study, the interactions between spiders, the two major horticultural pests, Bemisia tabaci and Frankliniella occidentalis , and their naturally occurring predators and parasitoids were evaluated in a mix of 21 newly planted shrubs selected for habitat management in a highly disturbed horticultural system. The effects of all factors were evaluated using redundancy analysis (RDA) and the generalized additive model (GAM) to assess the statistical significance of abundance of spiders and pests. The GAM showed that the abundance of both pests had a significant effect on hunter spider's abundance, whereas the abundance of B. tabaci , but not F. occidentalis , affected web-weavers' abundance. Ordination analysis showed that spider abundance closely correlated with that of B. tabaci but not with that of F. occidentalis , suggesting that complementarity occurs, and thereby probability of biocontrol, with respect to the targeted pest B. tabaci , although the temporal patterns of the spiders differed from those of F. occidentalis . Conservation strategies involving the establishment of these native plants around greenhouses could be an effective way to reduce pest populations outdoors.

Microorganisms associated with feathers of barn swallows in radioactively contaminated areas around chernobyl.

PubMed

Czirják, Gábor Arpád; Møller, Anders Pape; Mousseau, Timothy A; Heeb, Philipp

2010-08-01

The Chernobyl catastrophe provides a rare opportunity to study the ecological and evolutionary consequences of low-level, environmental radiation on living organisms. Despite some recent studies about negative effects of environmental radiation on macroorganisms, there is little knowledge about the effect of radioactive contamination on diversity and abundance of microorganisms. We examined abundance patterns of total cultivable bacteria and fungi and the abundance of feather-degrading bacterial subset present on feathers of barn swallows (Hirundo rustica), a colonial migratory passerine, around Chernobyl in relation to levels of ground level environmental radiation. After controlling for confounding variables, total cultivable bacterial loads were negatively correlated with environmental radioactivity, whereas abundance of fungi and feather-degrading bacteria was not significantly related to contamination levels. Abundance of both total and feather-degrading bacteria increased with barn swallow colony size, showing a potential cost of sociality. Males had lower abundance of feather-degrading bacteria than females. Our results show the detrimental effects of low-level environmental radiation on total cultivable bacterial assemblage on feathers, while the abundance of other microorganism groups living on barn swallow feathers, such as feather-degrading bacteria, are shaped by other factors like host sociality or host sex. These data lead us to conclude that the ecological effects of Chernobyl may be more general than previously assumed and may have long-term implications for host-microbe interactions and overall ecosystem functioning.

Galactic Abundance Patterns via Peimbert Types I & II Planetary Nebulae

NASA Astrophysics Data System (ADS)

Milingo, J. B.; Barnes, K. L.; Kwitter, K. B.; Souza, S. P.; Henry, R. B. C.; Skinner, J. N.

2005-12-01

Planetary Nebulae (PNe) are well known fonts of information about both stellar evolution and galactic chemical evolution. Abundance patterns in PNe are used to note signatures and constraints of nuclear processing, and as tracers of the distribution of metals throughout galaxies. In this poster abundance gradients and heavy element ratios are presented based upon newly acquired spectrophotometry of a sample of Galactic Peimbert Type I PNe. This new data set is extracted from spectra that extend from λ 3600 - 9600Å allowing the use of [S III] features at λ 9069 and 9532Å. Since a significant portion of S in PNe resides in S+2 and higher ionization stages, including these features improves the extrapolation from observed ion abundances to total element abundance. An alternate metallicity tracer, Sulfur is precluded from enhancement and depletion across the range of PNe progenitor masses. Its stability in intermediate mass stars makes it a useful tool to probe the natal conditions as well as the evolution of PNe progenitors. This is a continuation of our Type II PNe work, the impetus being to compile a relatively large set of line strengths and abundances with internally consistent observation, reduction, calibration, and abundance determination, minimizing systematic affects that come from compiling various data sets. This research is supported by the AAS Small Research Grants program, the Franklin & Marshall Committee on Grants, and NSF grant AST-0307118.

Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

USGS Publications Warehouse

Martin, B.A.; Saiki, M.K.

2005-01-01

We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

Spatio-temporal patterns in phytoplankton assemblages in inshore-offshore gradients using flow cytometry: A case study in the eastern English Channel

NASA Astrophysics Data System (ADS)

Bonato, Simon; Breton, Elsa; Didry, Morgane; Lizon, Fabrice; Cornille, Vincent; Lécuyer, Eric; Christaki, Urania; Artigas, Luis Felipe

2016-04-01

A pulse-shape recording flow cytometer (CytoSense©) was applied to the monitoring of changes in phytoplankton distribution along an inshore-offshore transect across the eastern English Channel (EEC), on 13 occasions during the main productive period of the year. Amongst the eight phytoplankton groups discriminated, picophytoplankton (picoeukaryotes and Synechococcus spp.) and Phaeocystis globosa nanoflagellates were the main contributors to total phytoplankton abundance, while Diatoms-like, Coccolithophores, and Cryptophytes represented each one less than 5%. High spatial resolution revealed important changes on relatively short distances. Moreover, a general decrease of Diatoms-like, P. globosa haploid cells, Coccolithophores, and picoeukaryote abundance was evidenced from inshore to offshore waters, associated with an increase of Synechococcus spp. abundance. Seasonal variability accounted for 71% of phytoplankton abundance changes. Compared to previous studies in the area the CytoSense allowed highlighting new players during the winter-spring-summer phytoplankton succession: (i) high abundance of Synechococcus spp. and picoeukaryotes I in winter and of Synechococcus spp. also in the summer, (ii) a transient abundance peak of picoeukaryotes II, and (iii) high abundance of Coccolithophores and Cryptophytes during the wax of P. globosa bloom and in the summer. The relationships between environmental variables and phytoplankton assemblages indicated that nutrients and the daily light intensity were the most important parameters in structuring the winter-spring-summer transitions.

Long-term changes in the planktonic cnidarian community in a mesoscale area of the NW Mediterranean

PubMed Central

Gili, Josep-Maria; Grinyó, Jordi; Raya, Vanesa; Sabatés, Ana

2018-01-01

In the present work, possible long-term changes in the planktonic cnidarian community were investigated by analyzing (1) species and community spatial distribution patterns, (2) variations in abundance and (3) changes in species richness during three mesoscale surveys representative of the climatic and anthropogenic changes that have occurred during the last three decades (years: 1983, 2004 and 2011) in the NW Mediterranean. These surveys were conducted during the summer (June) along the Catalan coast. All surveys covered the same area, used the same sampling methodology, and taxonomic identification was conducted by the same team of experts. An increase in the abundance of total cnidaria was found from 1983 to 2011. The siphonophore Muggiaea atlantica and the hydromedusa Aglaura hemistoma were the most abundant species, while Muggiaea kochii presented the largest abundance increment over time. Temperature was the main environmental parameter driving significant differences in the cnidarian community composition, abundance and spatial distribution patterns among the surveys. Our results suggest that in the current climate change scenario, warm-water species abundances will be positively favored, and the community will suffer changes in their latitudinal distribution patterns. We consider it extremely important to study and monitor gelatinous zooplankton in mesoscale spatial areas to understand not only long-term changes in abundances but also changes in their spatial distributions since spatial changes are sensitive indicators of climate change. PMID:29715282

Report on carbon and nitrogen abundance studies

NASA Technical Reports Server (NTRS)

Boehm-Vitense, Erika

1991-01-01

The aim of the proposal was to determine the nitrogen to carbon abundance ratios from transition layer lines in stars with different T(sub eff) and luminosities. The equations which give the surface emission line fluxes and the measured ratio of the NV to CIV emission line fluxes are presented and explained. The abundance results are compared with those of photospheric abundance studies for stars in common with the photospheric investigations. The results show that the analyses are at least as accurate as the photospheric determinations. These studies can be extended to F and early G stars for which photospheric abundance determinations for giants are hard to do because molecular bands become too weak. The abundance determination in the context of stellar evolution is addressed. The N/C abundance ratio increases steeply at the point of evolution for which the convection zone reaches deepest. Looking at the evolution of the rotation velocities v sin i, a steep decrease in v sin i is related to the increasing depth of the convection zone. It is concluded that the decrease in v sin i for T(sub eff) less than or approximately = 5800 K is most probably due to the rearrangement of the angular momentum in the stars due to deep convective mixing. It appears that the convection zone is rotating with nearly depth independent angular momentum. Other research results and ongoing projects are discussed.

Determinants of abundance and effects of blood-sucking flying insects in the nest of a hole-nesting bird.

PubMed

Tomás, Gustavo; Merino, Santiago; Martínez-de la Puente, Josué; Moreno, Juan; Morales, Judith; Lobato, Elisa

2008-05-01

Compared to non-flying nest-dwelling ectoparasites, the biology of most species of flying ectoparasites and its potential impact on avian hosts is poorly known and rarely, if ever, reported. In this study we explore for the first time the factors that may affect biting midge (Diptera: Ceratopogonidae) and black fly (Diptera: Simuliidae) abundances in the nest cavity of a bird, the hole-nesting blue tit Cyanistes caeruleus, and report their effects on adults and nestlings during reproduction. The abundance of biting midges was positively associated with nest mass, parental provisioning effort and abundance of blowflies and black flies, while negatively associated with nestling condition. Furthermore, a medication treatment to reduce blood parasitaemias in adult birds revealed that biting midges were more abundant in nests of females whose blood parasitaemias were experimentally reduced. This finding would be in accordance with these insect vectors attacking preferentially uninfected or less infected hosts to increase their own survival. The abundance of black flies in the population was lower than that of biting midges and increased in nests with later hatching dates. No significant effect of black fly abundance on adult or nestling condition was detected. Blood-sucking flying insects may impose specific, particular selection pressures on their hosts and more research is needed to better understand these host-parasite associations.

Global abundance of planktonic heterotrophic protists in the deep ocean.

PubMed

Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon

2015-03-01

The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml(-1) in mesopelagic waters down to 11±1 cells ml(-1) in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml(-1). The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web.

Variability of subseafloor viral abundance at the geographically and geologically distinct continental margins.

PubMed

Yanagawa, Katsunori; Morono, Yuki; Yoshida-Takashima, Yukari; Eitoku, Masamitsu; Sunamura, Michinari; Inagaki, Fumio; Imachi, Hiroyuki; Takai, Ken; Nunoura, Takuro

2014-04-01

We studied the relationship between viral particle and microbial cell abundances in marine subsurface sediments from three geographically distinct locations in the continental margins (offshore of the Shimokita Peninsula of Japan, the Cascadia Margin off Oregon, and the Gulf of Mexico) and found depth variations in viral abundances among these sites. Viruses in sediments obtained offshore of the Shimokita and in the Cascadia Margin generally decreased with increasing depth, whereas those in sediments from the Gulf of Mexico were relatively constant throughout the investigated depths. In addition, the abundance ratios of viruses to microbial cells notably varied among the sites, ranging between 10(-3) and 10(1) . The subseafloor viral abundance offshore of the Shimokita showed a positive relationship with the microbial cell abundance and the sediment porosity. In contrast, no statistically significant relationship was observed in the Cascadia Margin and the Gulf of Mexico sites, presumably due to the long-term preservation of viruses from enzymatic degradation within the low-porosity sediments. Our observations indicate that viral abundance in the marine subsurface sedimentary environment is regulated not only by in situ production but also by the balance of preservation and decay, which is associated with the regional sedimentation processes in the geological settings. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

High abundances of aerobic anoxygenic photosynthetic bacteria in the South Pacific Ocean.

PubMed

Lami, Raphaël; Cottrell, Matthew T; Ras, Joséphine; Ulloa, Osvaldo; Obernosterer, Ingrid; Claustre, Hervé; Kirchman, David L; Lebaron, Philippe

2007-07-01

Little is known about the abundance, distribution, and ecology of aerobic anoxygenic phototrophic (AAP) bacteria, particularly in oligotrophic environments, which represent 60% of the ocean. We investigated the abundance of AAP bacteria across the South Pacific Ocean, including the center of the gyre, the most oligotrophic water body of the world ocean. AAP bacteria, Prochlorococcus, and total prokaryotic abundances, as well as bacteriochlorophyll a (BChl a) and divinyl-chlorophyll a concentrations, were measured at several depths in the photic zone along a gradient of oligotrophic conditions. The abundances of AAP bacteria and Prochlorococcus were high, together accounting for up to 58% of the total prokaryotic community. The abundance of AAP bacteria alone was up to 1.94 x 10(5) cells ml(-1) and as high as 24% of the overall community. These measurements were consistent with the high BChl a concentrations (up to 3.32 x 10(-3) microg liter(-1)) found at all stations. However, the BChl a content per AAP bacterial cell was low, suggesting that AAP bacteria are mostly heterotrophic organisms. Interestingly, the biovolume and therefore biomass of AAP bacteria was on average twofold higher than that of other prokaryotic cells. This study demonstrates that AAP bacteria can be abundant in various oligotrophic conditions, including the most oligotrophic regime of the world ocean, and can account for a large part of the bacterioplanktonic carbon stock.

Rarity and extinction risk in coral reef angelfishes on isolated islands: interrelationships among abundance, geographic range size and specialisation

NASA Astrophysics Data System (ADS)

Hobbs, Jean-Paul A.; Jones, G. P.; Munday, P. L.

2010-03-01

Determining the species most vulnerable to increasing degradation of coral reef habitats requires identification of the ecological traits that increase extinction risk. In the terrestrial environment, endemic species often face a high risk of extinction because of an association among three traits that threaten species persistence: small geographic range size, low abundance and ecological specialisation. To test whether these traits are associated in coral reef fishes, this study compared abundance and specialisation in endemic and widespread angelfishes at the remote Christmas and Cocos Islands in the Indian Ocean. The interrelationships among traits conferring high extinction risk in terrestrial communities did not apply to these fishes. Endemic angelfishes were 50-80 times more abundant than widespread species at these islands. Furthermore, there was no relationship between abundance and ecological specialisation. Endemic species were not more specialised than widespread congeners and endemics used similar resources to many widespread species. Three widespread species exhibited low abundance and some degree of specialisation, which may expose them to a greater risk of local extinction. For endemic species, high abundance and lack of specialisation on susceptible habitats may compensate for the global extinction risk posed by having extremely small geographic ranges. However, recent extinctions of small range reef fishes confirm that endemics are not immune to the increasing severity of large-scale disturbances that can affect species throughout their geographic range.

Chemical Abundances of Two Stars in the Large Magellanic Cloud Globular Cluster NGC 1718

NASA Astrophysics Data System (ADS)

Sakari, Charli M.; McWilliam, Andrew; Wallerstein, George

2017-05-01

Detailed chemical abundances of two stars in the intermediate-age Large Magellanic Cloud (LMC) globular cluster NGC 1718 are presented, based on high-resolution spectroscopic observations with the MIKE spectrograph. The detailed abundances confirm NGC 1718 to be a fairly metal-rich cluster, with an average [Fe/H] ˜ -0.55 ± 0.01. The two red giants appear to have primordial O, Na, Mg and Al abundances, with no convincing signs of a composition difference between the two stars - hence, based on these two stars, NGC 1718 shows no evidence for hosting multiple populations. The Mg abundance is lower than Milky Way field stars, but is similar to LMC field stars at the same metallicity. The previous claims of very low [Mg/Fe] in NGC 1718 are therefore not supported in this study. Other abundances (Si, Ca, Ti, V, Mn, Ni, Cu, Rb, Y, Zr, La and Eu) all follow the LMC field star trend, demonstrating yet again that (for most elements) globular clusters trace the abundances of their host galaxy's field stars. Similar to the field stars, NGC 1718 is found to be mildly deficient in explosive α-elements, but moderately to strongly deficient in O, Na, Mg, Al and Cu, elements that form during hydrostatic burning in massive stars. NGC 1718 is also enhanced in La, suggesting that it was enriched in ejecta from metal-poor asymptotic giant branch stars.

Does small-scale vertical distribution of juvenile schooling fish affect prey availability to surface-feeding seabirds in the Wadden Sea?

NASA Astrophysics Data System (ADS)

Dänhardt, Andreas; Becker, Peter H.

2011-02-01

Food availability is a key variable influencing breeding performance and demography of marine top predators. Due to methodological problems, proportionality between fish abundance and availability is often assumed without being explicitly tested. More specifically, better breeding performance of surface-feeding seabirds at times of large prey stocks suggests that prey availability is also a function of prey abundance. Using vertically resolved stow net sampling we tested whether local abundance and length composition of pelagic fish are reliable predictors of the availability of these fish to surface-feeding Common Terns ( Sterna hirundo) breeding in the German Wadden Sea. Prey fish were found to concentrate below the maximum diving depth of the terns. Individuals caught close to the surface were in most cases smaller than conspecifics caught at greater depth. Correlations between fish abundance within and out of reach of the terns appeared to be both species- and site-specific rather than driven by overall fish abundance. Vertical distribution patterns of the terns' main prey fish could be explained as anti-predator behavior, reducing prey availability to the terns. In 2007, when breeding performance was much better than in 2006, herring and whiting were much more abundant, suggesting that overall prey abundance may also increase prey availability in habitats other than those represented by the stow net sampling.

Seasonal patterns of aster leafhopper (Hemiptera: Cicadellidae) abundance and aster yellows phytoplasma infectivity in Wisconsin carrot fields.

PubMed

Frost, K E; Esker, P D; Van Haren, R; Kotolski, L; Groves, R L

2013-06-01

In Wisconsin, vegetable crops are threatened annually by the aster yellows phytoplasma (AYp), which is obligately transmitted by the aster leafhopper. Using a multiyear, multilocation data set, seasonal patterns of leafhopper abundance and infectivity were modeled. A seasonal aster yellows index (AYI) was deduced from the model abundance and infectivity predictions to represent the expected seasonal risk of pathogen transmission by infectious aster leafhoppers. The primary goal of this study was to identify periods of time during the growing season when crop protection practices could be targeted to reduce the risk of AYp spread. Based on abundance and infectivity, the annual exposure of the carrot crop to infectious leafhoppers varied by 16- and 70-fold, respectively. Together, this corresponded to an estimated 1,000-fold difference in exposure to infectious leafhoppers. Within a season, exposure of the crop to infectious aster leafhoppers (Macrosteles quadrilineatus Forbes), varied threefold because of abundance and ninefold because of infectivity. Periods of above average aster leafhopper abundance occurred between 11 June and 2 August and above average infectivity occurred between 27 May and 13 July. A more comprehensive description of the temporal trends of aster leafhopper abundance and infectivity provides new information defining when the aster leafhopper moves into susceptible crop fields and when they transmit the pathogen to susceptible crops.

Predicting probability of occurrence and factors affecting distribution and abundance of three Ozark endemic crayfish species at multiple spatial scales

USGS Publications Warehouse

Nolen, Matthew S.; Magoulick, Daniel D.; DiStefano, Robert J.; Imhoff, Emily M.; Wagner, Brian K.

2014-01-01

We found that a range of environmental variables were important in predicting crayfish distribution and abundance at multiple spatial scales and their importance was species-, response variable- and scale dependent. We would encourage others to examine the influence of spatial scale on species distribution and abundance patterns.

Relative abundance and species richness of terrestrial salamanders on hardwood ecosystem experiment sites before harvesting

Treesearch

Jami E. MacNeil; Rod N. Williams

2013-01-01

Terrestrial salamanders are ideal indicators of forest ecosystem integrity due to their abundance, their role in nutrient cycling, and their sensitivity to environmental change. To understand better how terrestrial salamanders are affected by forest management practices, we monitored species diversity and abundance before implementation of timber harvests within the...

Abundance of introduced species at home predicts abundance away in herbaceous communities

Treesearch

J. Firn; J.L. Moore; A.S. MacDougall; E.T. Borer; E.W. Seabloom; J. HilleRisLambers; S. Harpole; E.E. Cleland; C.S. Brown; J.M.H. Knops; S.M. Prober; D.A. Pyke; K.A. Farrell; J.D. Bakker; L.R. O’Halloran; P.B. Adler; S.L. Collins; C.M. D’Antonio; M.J. Crawley; E.M. Wolkovich; K.J. La Pierre; B.A. Melbourne; Y. Hautier; J.W. Morgan; A.D.B. Leakey; A.D. Kay; R.L. McCulley; K.F. Davies; C.J. Stevens; C.J. Chu

2011-01-01

Many ecosystems worldwide are dominated by introduced plant species, leading to loss of biodiversity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced vs. native communities, because ecological or evolutionary-based shifts in populations underlie invasion success. Here, data for 26 herbaceous species at...

Cosmochemistry

NASA Astrophysics Data System (ADS)

Esteban, C.; García López, R. J.; Herrero, A.; Sánchez, F.

2004-03-01

1. Primordial alchemy: from the Big Bang to the present Universe G. Steigman; 2. Stellar nucleosynthesis N. Langer; 3. Obervational aspects of stellar nucleosynthesis D. L. Lambert; 4. Abundance determinations in HII regions and planetary nebulae G. Stasinska; 5. Element abundances in nearby galaxies D. R. Garnett; 6. Chemical evolution of galaxies and intracluster medium F.Matteucci; 7. Element abundances through the cosmic ages M. Pettini.

Cosmochemistry

NASA Astrophysics Data System (ADS)

Esteban, C.; García López, R. J.; Herrero, A.; Sánchez, F.

2011-01-01

1. Primordial alchemy: from the Big Bang to the present Universe G. Steigman; 2. Stellar nucleosynthesis N. Langer; 3. Obervational aspects of stellar nucleosynthesis D. L. Lambert; 4. Abundance determinations in HII regions and planetary nebulae G. Stasinska; 5. Element abundances in nearby galaxies D. R. Garnett; 6. Chemical evolution of galaxies and intracluster medium F.Matteucci; 7. Element abundances through the cosmic ages M. Pettini.

Seasonality and abundance of truffles from oak woodlands to red fir forests

Treesearch

Malcolm P. North

2002-01-01

Truffles are an important food source for many small mammals in forest ecosystems; however, we know little about the seasonality, abundance, or diversity of the truffle community in the Sierra Nevada. This study examined how truffle abundance and diversity varied between oak woodland, ponderosa pine (Pinus ponderosa), mixed-conifer, and red fir (

Dynamic N -occupancy models: estimating demographic rates and local abundance from detection-nondetection data

Treesearch

Sam Rossman; Charles B. Yackulic; Sarah P. Saunders; Janice Reid; Ray Davis; Elise F. Zipkin

2016-01-01

Occupancy modeling is a widely used analytical technique for assessing species distributions and range dynamics. However, occupancy analyses frequently ignore variation in abundance of occupied sites, even though site abundances affect many of the parameters being estimated (e.g., extinction, colonization, detection probability). We introduce a new model (“dynamic

Community structure and abundance of benthic infaunal invertebrates in Maine fringing marsh ecosystems

Treesearch

Richard A. MacKenzie; Michele Dionne; Jeremy Miller; Michael Haas; Pamela A. Morgan

2015-01-01

Fringing marshes are abundant ecosystems that dominate the New England coastline. Despite their abundance, very little baseline data is available from them and few studies have documented the ecosystems services that they provide. This information is important for conservation efforts as well as for an increased understanding of how fringing marshes function compared...

Wintering Yellow-rumped Warblers (Dendroica coronata) track manipulated abundance of Myrica cerifera fruits

Treesearch

Kathi L. Borgmann; Scott F. Pearson; Douglas J. Levey; Cathryn H. Greenberg

2004-01-01

Food availability during winter may determine habitat use and limit populations of overwintering birds, yet its importance is difficult to judge because few studies have experimentally tested the response of nonbreedlng birds to changes in resource abundance. We expenmentally examined the link between fruit availability and habitat use by manipulating winter abundance...

Coyote abundance in relation to habitat characteristics in Sierra San Luis, Sonora, Mexico

Treesearch

Eduardo Ponce Guevara; Karla Pelz Serrano; Carlos A. Lopez Gonzalez

2005-01-01

Coyotes have expanded their historical distribution range because of anthropogenic activities and habitat transformation, where forests have been considered marginal habitat. We tested the relationship between vegetation structure and coyote abundance in different habitat types. We expected to find a higher abundance in open lands than in thicker areas. We used scent...

Soil Temperature and Moisture Effects on Soil Respiration and Microbial Community Abundance

DTIC Science & Technology

2015-04-13

highest abundance of bacteria and archaea. Across all soils, if the moisture content was optimal but the temperature was around 5°C, the respiration...9 3.3 Abundance of soil bacteria and archaea ..................................................................... 10 4...ARTEMIS Army Terrestrial-Environmental Modeling and Intelligence System ATCC American Type Culture Collection Ca Calcium CEC Cation Exchange Capacity

Influence of inelastic collisions with hydrogen atoms on the non-LTE modelling of Ca I and Ca II lines in late-type stars

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Sitnova, T.; Belyaev, A. K.

2017-09-01

We performed the non-local thermodynamic equilibrium (non-LTE, NLTE) calculations for Ca I-II with the updated model atom that includes new quantum-mechanical rate coefficients for Ca I + H I collisions from two recent studies and investigated the accuracy of calcium abundance determinations using the Sun, Procyon, and five metal-poor (MP, -2.6 ≤ [Fe/H] ≤-1.3) stars with well-determined stellar parameters. Including H I collisions substantially reduces over-ionisation of Ca I in the line formation layers compared with the case of pure electronic collisions and thus the NLTE effects on abundances derived from Ca I lines. We show that both collisional recipes lead to very similar NLTE results. As for Ca II, the classical Drawinian rates scaled by SH = 0.1 are still applied. When using the subordinate lines of Ca I and the high-excitation lines of Ca II, NLTE provides the smaller line-to-line scatter compared with the LTE case for each star. For Procyon, NLTE removes a steep trend with line strength among strong Ca I lines seen in LTE and leads to consistent [Ca/H] abundances from the two ionisation stages. In the MP stars, the NLTE abundance from Ca II 8498 Å agrees well with the abundance from the Ca I subordinate lines, in contrast to LTE, where the abundance difference grows towards lower metallicity and reaches 0.46 dex in BD -13°3442 ([Fe/H] = -2.62). NLTE largely removes abundance discrepancies between the high-excitation lines of Ca II and Ca II 8498 Å obtained for our four [Fe/H] < -2 stars under the LTE assumption. We investigated the formation of the Ca I resonance line in the [Fe/H] < -2 stars. When the calcium abundance varies between [Ca/H] ≃ -1.8 and -2.3, photon loss in the resonance line itself in the uppermost atmospheric layers drives the strengthening of the line core compared with the LTE case, and this effect prevails over the weakening of the line wings, resulting in negative NLTE abundance correction and underestimation of the abundance derived from Ca I 4226 Å compared with that from the subordinate lines, by 0.08 to 0.32 dex. This problem may be related to the use of classical homogeneous (1D) model atmospheres. The situation is improved when the calcium abundance decreases and the Ca I 4226 Å line formation depths are shifted into deep atmospheric layers that are dominated by over-ionisation of Ca I. However, the departures from LTE are still underestimated for Ca I 4226 Å at [Ca/H] ≃ -4.4 (HE 0557-4840). Consistent NLTE abundances from the Ca I resonance line and the Ca II lines are found for HE 0107-5240 and HE 1327-2326 with [Ca/H] ≤-5. Thus, the Ca I/Ca II ionisation equilibrium method can successfully be applied to determine surface gravities of [Ca/H] ≾ -5 stars. We provide the NLTE abundance corrections for 28 lines of Ca I in a grid of model atmospheres with 5000 K ≤ Teff ≤ 6500 K, 2.5 ≤ log g ≤ 4.5, -4 ≤ [Fe/H] ≤ 0, which is suitable for abundance analysis of FGK-type dwarfs and subgiants.

New aerial survey and hierarchical model to estimate manatee abundance

USGS Publications Warehouse

Langimm, Cahterine A.; Dorazio, Robert M.; Stith, Bradley M.; Doyle, Terry J.

2011-01-01

Monitoring the response of endangered and protected species to hydrological restoration is a major component of the adaptive management framework of the Comprehensive Everglades Restoration Plan. The endangered Florida manatee (Trichechus manatus latirostris) lives at the marine-freshwater interface in southwest Florida and is likely to be affected by hydrologic restoration. To provide managers with prerestoration information on distribution and abundance for postrestoration comparison, we developed and implemented a new aerial survey design and hierarchical statistical model to estimate and map abundance of manatees as a function of patch-specific habitat characteristics, indicative of manatee requirements for offshore forage (seagrass), inland fresh drinking water, and warm-water winter refuge. We estimated the number of groups of manatees from dual-observer counts and estimated the number of individuals within groups by removal sampling. Our model is unique in that we jointly analyzed group and individual counts using assumptions that allow probabilities of group detection to depend on group size. Ours is the first analysis of manatee aerial surveys to model spatial and temporal abundance of manatees in association with habitat type while accounting for imperfect detection. We conducted the study in the Ten Thousand Islands area of southwestern Florida, USA, which was expected to be affected by the Picayune Strand Restoration Project to restore hydrology altered for a failed real-estate development. We conducted 11 surveys in 2006, spanning the cold, dry season and warm, wet season. To examine short-term and seasonal changes in distribution we flew paired surveys 1–2 days apart within a given month during the year. Manatees were sparsely distributed across the landscape in small groups. Probability of detection of a group increased with group size; the magnitude of the relationship between group size and detection probability varied among surveys. Probability of detection of individual manatees within a group also differed among surveys, ranging from a low of 0.27 on 11 January to a high of 0.73 on 8 August. During winter surveys, abundance was always higher inland at Port of the Islands (POI), a manatee warm-water aggregation site, than in the other habitat types. During warm-season surveys, highest abundances were estimated in offshore habitat where manatees forage on seagrass. Manatees continued to use POI in summer, but in lower numbers than in winter, possibly to drink freshwater. Abundance in other inland systems and inshore bays was low compared to POI in winter and summer, possibly because of low availability of freshwater. During cold weather, maps of patch abundance of paired surveys showed daily changes in manatee distribution associated with rapid changes in air and water temperature as manatees sought warm water with falling temperatures and seagrass areas with increasing temperatures. Within a habitat type, some patches had higher manatee abundance suggesting differences in quality, possibly due to freshwater flow. If hydrological restoration alters the location of quality habitat, postrestoration comparisons using our methods will document how manatees adjust to new resources, providing managers with information on spatial needs for further monitoring or management. Total abundance for the entire area was similar among survey dates. Credible intervals however were large on a few surveys, and may limit our ability to statistically detect trends in total abundance. Additional modeling of abundance with time- and patch-specific covariates of salinity, water temperature, and seagrass abundance will directly link manatee abundance with physical and biological changes due to restoration and should decrease uncertainty of estimates.

Normalization and microbial differential abundance strategies depend upon data characteristics.

PubMed

Weiss, Sophie; Xu, Zhenjiang Zech; Peddada, Shyamal; Amir, Amnon; Bittinger, Kyle; Gonzalez, Antonio; Lozupone, Catherine; Zaneveld, Jesse R; Vázquez-Baeza, Yoshiki; Birmingham, Amanda; Hyde, Embriette R; Knight, Rob

2017-03-03

Data from 16S ribosomal RNA (rRNA) amplicon sequencing present challenges to ecological and statistical interpretation. In particular, library sizes often vary over several ranges of magnitude, and the data contains many zeros. Although we are typically interested in comparing relative abundance of taxa in the ecosystem of two or more groups, we can only measure the taxon relative abundance in specimens obtained from the ecosystems. Because the comparison of taxon relative abundance in the specimen is not equivalent to the comparison of taxon relative abundance in the ecosystems, this presents a special challenge. Second, because the relative abundance of taxa in the specimen (as well as in the ecosystem) sum to 1, these are compositional data. Because the compositional data are constrained by the simplex (sum to 1) and are not unconstrained in the Euclidean space, many standard methods of analysis are not applicable. Here, we evaluate how these challenges impact the performance of existing normalization methods and differential abundance analyses. Effects on normalization: Most normalization methods enable successful clustering of samples according to biological origin when the groups differ substantially in their overall microbial composition. Rarefying more clearly clusters samples according to biological origin than other normalization techniques do for ordination metrics based on presence or absence. Alternate normalization measures are potentially vulnerable to artifacts due to library size. Effects on differential abundance testing: We build on a previous work to evaluate seven proposed statistical methods using rarefied as well as raw data. Our simulation studies suggest that the false discovery rates of many differential abundance-testing methods are not increased by rarefying itself, although of course rarefying results in a loss of sensitivity due to elimination of a portion of available data. For groups with large (~10×) differences in the average library size, rarefying lowers the false discovery rate. DESeq2, without addition of a constant, increased sensitivity on smaller datasets (<20 samples per group) but tends towards a higher false discovery rate with more samples, very uneven (~10×) library sizes, and/or compositional effects. For drawing inferences regarding taxon abundance in the ecosystem, analysis of composition of microbiomes (ANCOM) is not only very sensitive (for >20 samples per group) but also critically the only method tested that has a good control of false discovery rate. These findings guide which normalization and differential abundance techniques to use based on the data characteristics of a given study.

Desires and management preferences of stakeholders regarding feral cats in the Hawaiian islands.

PubMed

Lohr, Cheryl A; Lepczyk, Christopher A

2014-04-01

Feral cats are abundant in many parts of the world and a source of conservation conflict. Our goal was to clarify the beliefs and desires held by stakeholders regarding feral cat abundance and management. We measured people's desired abundance of feral cats in the Hawaiian Islands and identified an order of preference for 7 feral cat management techniques. In 2011 we disseminated a survey to 5407 Hawaii residents. Approximately 46% of preidentified stakeholders and 20% of random residents responded to the survey (1510 surveys returned). Results from the potential for conflict index revealed a high level of consensus (86.9% of respondents) that feral cat abundance should be decreased. The 3 most common explanatory variables for respondents' stated desires were enjoyment from seeing feral cats (84%), intrinsic value of feral cats (12%), and threat to native fauna (73%). The frequency with which respondents saw cats and change in the perceived abundance of cats also affected respondent's desired abundance of cats; 41.3% of respondents stated that they saw feral cats daily and 44.7% stated that the cat population had increased in recent years. Other potential environmental impacts of feral cats had little affect on desired abundance. The majority of respondents (78%) supported removing feral cats from the natural environment permanently. Consensus convergence models with data from 1388 respondents who completed the relevant questions showed live capture and lethal injection was the most preferred technique and trap-neuter-release was the least preferred technique for managing feral cats. However, the acceptability of each technique varied among stakeholders. Our results suggest that the majority of Hawaii's residents would like to see effective management that reduces the abundance of feral or free-roaming cats. © 2013 Society for Conservation Biology.

Meiofauna abundance and community patterns along a transatlantic transect in the Vema Fracture Zone and in the hadal zone of the Puerto Rico trench

NASA Astrophysics Data System (ADS)

Schmidt, Christina; Escobar Wolf, Kaibil; Lins, Lidia; Martínez Arbizu, Pedro; Brandt, Angelika

2018-02-01

Despite the increasing sampling effort that occurred in the deep-sea environment during the last decades, knowledge about meiofauna ecology in trenches and Fracture Zones is still scarce. Based on the lack of this information, a longitudinal transect across the Vema Fracture Zone in the North Atlantic was sampled to test whether meiofauna abundances differ between Northeast and Northwest Atlantic basins, separated by the Mid-Atlantic Ridge. Also, for examination of meiofauna depth pattern, the Puerto Rico trench floor, its upper trench slope and the Western North Atlantic abyssal were investigated. In this study, meiofauna communities were dominated by Nematoda (93%) and Copepoda (4%). The highest total abundance of meiofauna was found in the Puerto Rico trench and the lowest in the Western basin. We found significant differences between the Eastern and Western Atlantic basins, which were potentially caused by differences in current regimes. Stronger currents observed in the Western basin possibly led to the coarser sediment grain size observed in this region, and consequently to the lower abundances of the major groups found there. Besides grain size, the total abundance of meiofauna was significantly correlated with total nitrogen, total organic carbon, and water depth. Moreover, our study reveals a trend of increasing abundance of total meiofauna with increasing water depth in the Puerto Rico trench. Also, significant differences between the Western abyssal and the Puerto Rico trench were discovered. Generally, the meiofauna abundance in the investigated area decreased from East to West but increased with increasing water depth in the Puerto Rico trench. Due to funnelling of organic sediments increased food availability towards deeper regions in trenches could occur and promote higher abundance.

Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): a study supported by a citizen science project.

PubMed

Hidalgo-Ruz, Valeria; Thiel, Martin

2013-01-01

The accumulation of large and small plastic debris is a problem throughout the world's oceans and coastlines. Abundances and types of small plastic debris have only been reported for some isolated beaches in the SE Pacific, but these data are insufficient to evaluate the situation in this region. The citizen science project "National Sampling of Small Plastic Debris" was supported by schoolchildren from all over Chile who documented the distribution and abundance of small plastic debris on Chilean beaches. Thirty-nine schools and nearly 1000 students from continental Chile and Easter Island participated in the activity. To validate the data obtained by the students, all samples were recounted in the laboratory. The results of the present study showed that the students were able to follow the instructions and generate reliable data. The average abundance obtained was 27 small plastic pieces per m(2) for the continental coast of Chile, but the samples from Easter Island had extraordinarily higher abundances (>800 items per m(2)). The abundance of small plastic debris on the continental coast could be associated with coastal urban centers and their economic activities. The high abundance found on Easter Island can be explained mainly by the transport of plastic debris via the surface currents in the South Pacific Subtropical Gyre, resulting in the accumulation of small plastic debris on the beaches of the island. This first report of the widespread distribution and abundance of small plastic debris on Chilean beaches underscores the need to extend plastic debris research to ecological aspects of the problem and to improve waste management. Copyright © 2013 Elsevier Ltd. All rights reserved.

Energy density and variability in abundance of pigeon guillemot prey: Support for the quality-variability trade-off hypothesis

USGS Publications Warehouse

Litzow, Michael A.; Piatt, John F.; Abookire, Alisa A.; Robards, Martin D.

2004-01-01

1. The quality-variability trade-off hypothesis predicts that (i) energy density (kJ g-1) and spatial-temporal variability in abundance are positively correlated in nearshore marine fishes; and (ii) prey selection by a nearshore piscivore, the pigeon guillemot (Cepphus columba Pallas), is negatively affected by variability in abundance. 2. We tested these predictions with data from a 4-year study that measured fish abundance with beach seines and pigeon guillemot prey utilization with visual identification of chick meals. 3. The first prediction was supported. Pearson's correlation showed that fishes with higher energy density were more variable on seasonal (r = 0.71) and annual (r = 0.66) time scales. Higher energy density fishes were also more abundant overall (r = 0.85) and more patchy at a scale of 10s of km (r = 0.77). 4. Prey utilization by pigeon guillemots was strongly non-random. Relative preference, defined as the difference between log-ratio transformed proportions of individual prey taxa in chick diets and beach seine catches, was significantly different from zero for seven of the eight main prey categories. 5. The second prediction was also supported. We used principal component analysis (PCA) to summarize variability in correlated prey characteristics (energy density, availability and variability in abundance). Two PCA scores explained 32% of observed variability in pigeon guillemot prey utilization. Seasonal variability in abundance was negatively weighted by these PCA scores, providing evidence of risk-averse selection. Prey availability, energy density and km-scale variability in abundance were positively weighted. 6. Trophic interactions are known to create variability in resource distribution in other systems. We propose that links between resource quality and the strength of trophic interactions may produce resource quality-variability trade-offs.

Local and Landscape Drivers of Parasitoid Abundance, Richness, and Composition in Urban Gardens.

PubMed

Burks, Julia M; Philpott, Stacy M

2017-04-01

Urbanization negatively affects biodiversity, yet some urban habitat features can support diversity. Parasitoid wasps, an abundant and highly diverse group of arthropods, can inhabit urban areas and do well in areas with higher host abundance, floral resources, or local or landscape complexity. Parasitoids provide biological control services in many agricultural habitats, yet few studies have examined diversity and abundance of parasitoids in urban agroecosystems to understand how to promote conservation and function. We examined the local habitat and landscape drivers of parasitoid abundance, superfamily and family richness, and parasitoid composition in urban gardens in the California central coast. Local factors included garden size, ground cover type, herbaceous plant species, and number of trees and shrubs. Landscape characteristics included land cover and landscape diversity around gardens. We found that garden size, mulch cover, and urban cover within 500 m of gardens predicted increases in parasitoid abundance within gardens. The height of herbaceous vegetation and tree and shrub richness predicted increases in superfamily and family richness whereas increases in urban cover resulted in declines in parasitoid richness. Abundance of individual superfamilies and families responded to a wide array of local and landscape factors, sometimes in opposite ways. Composition of parasitoid communities responded to changes in garden size, herbaceous plant cover, and number of flowers. Thus, both local scale management and landscape planning may impact the abundance, diversity, and community composition of parasitoids in urban gardens, and may result in differences in the effectiveness of parasitoids in biological control. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

How Habitat Change and Rainfall Affect Dung Beetle Diversity in Caatinga, a Brazilian Semi-Arid Ecosystem

PubMed Central

Liberal, Carolina Nunes; de Farias, Ângela Maria Isidro; Meiado, Marcos Vinicius; Filgueiras, Bruno K. C.; Iannuzzi, Luciana

2011-01-01

The aim of the present study was to evaluate how dung beetle communities respond to both environment and rainfall in the Caatinga, a semi-arid ecosystem in northeastern Brazil. The communities were sampled monthly from May 2006 to April 2007 using pitfall traps baited with human feces in two environments denominated “land use area” and “undisturbed area.” Abundance and species richness were compared between the two environments and two seasons (dry and wet season) using a generalized linear model with a Poisson error distribution. Diversity was compared between the two environments (land use area and undisturbed area) and seasons (dry and wet) using the Two-Way ANOVA test. Non-metric multidimensional scaling was performed on the resemblance matrix of Bray-Curtis distances (with 1000 random restarts) to determine whether disturbance affected the abundance and species composition of the dung beetle communities. Spearman's correlation coefficient was used to determine whether rainfall was correlated with abundance and species richness. A total of 1097 specimens belonging to 13 species were collected. The most abundant and frequent species was Dichotomius geminatus Arrow (Coleoptera: Scarabaeidae). The environment exerted an influence over abundance. Abundance and diversity were affected by season, with an increase in abundance at the beginning of the wet season. The correlation coefficient values were high and significant for abundance and species richness, which were both correlated to rainfall. In conclusion, the restriction of species to some environments demonstrates the need to preserve these areas in order to avoid possible local extinction. Therefore, in extremely seasonable environments, such as the Caatinga, seasonal variation strongly affects dung beetle communities. PMID:22224924

How habitat change and rainfall affect dung beetle diversity in Caatinga, a Brazilian semi-arid ecosystem.

PubMed

Liberal, Carolina Nunes; de Farias, Ângela Maria Isidro; Meiado, Marcos Vinicius; Filgueiras, Bruno K C; Iannuzzi, Luciana

2011-01-01

The aim of the present study was to evaluate how dung beetle communities respond to both environment and rainfall in the Caatinga, a semi-arid ecosystem in northeastern Brazil. The communities were sampled monthly from May 2006 to April 2007 using pitfall traps baited with human feces in two environments denominated "land use area" and "undisturbed area." Abundance and species richness were compared between the two environments and two seasons (dry and wet season) using a generalized linear model with a Poisson error distribution. Diversity was compared between the two environments (land use area and undisturbed area) and seasons (dry and wet) using the Two-Way ANOVA test. Non-metric multidimensional scaling was performed on the resemblance matrix of Bray-Curtis distances (with 1000 random restarts) to determine whether disturbance affected the abundance and species composition of the dung beetle communities. Spearman's correlation coefficient was used to determine whether rainfall was correlated with abundance and species richness. A total of 1097 specimens belonging to 13 species were collected. The most abundant and frequent species was Dichotomius geminatus Arrow (Coleoptera: Scarabaeidae). The environment exerted an influence over abundance. Abundance and diversity were affected by season, with an increase in abundance at the beginning of the wet season. The correlation coefficient values were high and significant for abundance and species richness, which were both correlated to rainfall. In conclusion, the restriction of species to some environments demonstrates the need to preserve these areas in order to avoid possible local extinction. Therefore, in extremely seasonable environments, such as the Caatinga, seasonal variation strongly affects dung beetle communities.

BORON ABUNDANCES ACROSS THE “Li–Be DIP” IN THE HYADES CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boesgaard, Ann Merchant; Lum, Michael G.; Deliyannis, Constantine P.

2016-10-10

Dramatic deficiencies of Li in the mid-F dwarf stars of the Hyades cluster were discovered by Boesgaard and Tripicco. Boesgaard and King discovered corresponding, but smaller, deficiencies in Be in the same narrow temperature region in the Hyades. Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope , we investigate B abundances in the Hyades F stars to look for a potential B dip using the B i resonance line at 2496.8 Å. The light elements Li, Be, and B are destroyed inside stars at increasingly hotter temperatures: 2.5, 3.5, and 5 × 10{sup 6} K, respectively. Consequently,more » these elements survive to increasingly greater depths in a star and their surface abundances indicate the depth and thoroughness of mixing in the star. We have (re)determined Li abundances/upper limits for 79 Hyades dwarfs, Be for 43 stars, and B for 5 stars. We find evidence for a small drop in the B abundance across the Li–Be dip. The B abundances for the four stars in the temperature range 6100–6730 K fit the B–Be correlation found previously by Boesgaard et al. Models of rotational mixing produce good agreement with the relative depletions of Be and B in the dip region. We have compared our nLTE B abundances for the three high B stars on either side of the Li–Be dip with those found by Duncan et al. for the two Hyades giants. This confirms the factor of 10 decline in the B abundance in the Hyades giants as predicted by dilution due to the deepening of the surface convection zone.« less

Change in avian abundance predicted from regional forest inventory data

USGS Publications Warehouse

Twedt, Daniel J.; Tirpak, John M.; Jones-Farrand, D. Todd; Thompson, Frank R.; Uihlein, William B.; Fitzgerald, Jane A.

2010-01-01

An inability to predict population response to future habitat projections is a shortcoming in bird conservation planning. We sought to predict avian response to projections of future forest conditions that were developed from nationwide forest surveys within the Forest Inventory and Analysis (FIA) program. To accomplish this, we evaluated the historical relationship between silvicolous bird populations and FIA-derived forest conditions within 25 ecoregions that comprise the southeastern United States. We aggregated forest area by forest ownership, forest type, and tree size-class categories in county-based ecoregions for 5 time periods spanning 1963-2008. We assessed the relationship of forest data with contemporaneous indices of abundance for 24 silvicolous bird species that were obtained from Breeding Bird Surveys. Relationships between bird abundance and forest inventory data for 18 species were deemed sufficient as predictive models. We used these empirically derived relationships between regional forest conditions and bird populations to predict relative changes in abundance of these species within ecoregions that are anticipated to coincide with projected changes in forest variables through 2040. Predicted abundances of these 18 species are expected to remain relatively stable in over a quarter (27%) of the ecoregions. However, change in forest area and redistribution of forest types will likely result in changed abundance of some species within many ecosystems. For example, abundances of 11 species, including pine warbler (Dendroica pinus), brown-headed nuthatch (Sitta pusilla), and chuckwills- widow (Caprimulgus carolinensis), are projected to increase within more ecoregions than ecoregions where they will decrease. For 6 other species, such as blue-winged warbler (Vermivora pinus), Carolina wren (Thryothorus ludovicianus), and indigo bunting (Passerina cyanea), we projected abundances will decrease within more ecoregions than ecoregions where they will increase.

Ocean time-series reveals recurring seasonal patterns of virioplankton dynamics in the northwestern Sargasso Sea.

PubMed

Parsons, Rachel J; Breitbart, Mya; Lomas, Michael W; Carlson, Craig A

2012-02-01

There are an estimated 10(30) virioplankton in the world oceans, the majority of which are phages (viruses that infect bacteria). Marine phages encompass enormous genetic diversity, affect biogeochemical cycling of elements, and partially control aspects of prokaryotic production and diversity. Despite their importance, there is a paucity of data describing virioplankton distributions over time and depth in oceanic systems. A decade of high-resolution time-series data collected from the upper 300 m in the northwestern Sargasso Sea revealed recurring temporal and vertical patterns of virioplankton abundance in unprecedented detail. An annual virioplankton maximum developed between 60 and 100 m during periods of summer stratification and eroded during winter convective mixing. The timing and vertical positioning of this seasonal pattern was related to variability in water column stability and the dynamics of specific picophytoplankton and heterotrophic bacterioplankton lineages. Between 60 and 100 m, virioplankton abundance was negatively correlated to the dominant heterotrophic bacterioplankton lineage SAR11, as well as the less abundant picophytoplankton, Synechococcus. In contrast, virioplankton abundance was positively correlated to the dominant picophytoplankton lineage Prochlorococcus, and the less abundant alpha-proteobacteria, Rhodobacteraceae. Seasonally, virioplankton abundances were highly synchronous with Prochlorococcus distributions and the virioplankton to Prochlorococcus ratio remained remarkably constant during periods of water column stratification. The data suggest that a significant fraction of viruses in the mid-euphotic zone of the subtropical gyres may be cyanophages and patterns in their abundance are largely determined by Prochlorococcus dynamics in response to water column stability. This high-resolution, decadal survey of virioplankton abundance provides insight into the possible controls of virioplankton dynamics in the open ocean.

Cross-correlation map analyses show weather variation influences on mosquito abundance patterns in Saginaw County, Michigan, 1989-2005.

PubMed

Chuang, Ting-Wu; Ionides, Edward L; Knepper, Randall G; Stanuszek, William W; Walker, Edward D; Wilson, Mark L

2012-07-01

Weather is important determinant of mosquito abundance that, in turn, influences vectorborne disease dynamics. In temperate regions, transmission generally is seasonal as mosquito abundance and behavior varies with temperature, precipitation, and other meteorological factors. We investigated how such factors affected species-specific mosquito abundance patterns in Saginaw County, MI, during a 17-yr period. Systematic sampling was undertaken at 22 trapping sites from May to September, during 1989-2005, for 19,228 trap-nights and 300,770 mosquitoes in total. Aedes vexans (Meigen), Culex pipiens L. and Culex restuans Theobald, the most abundant species, were analyzed. Weather data included local daily maximum temperature, minimum temperature, total precipitation, and average relative humidity. In addition to standard statistical methods, cross-correlation mapping was used to evaluate temporal associations with various lag periods between weather variables and species-specific mosquito abundances. Overall, the average number of mosquitoes was 4.90 per trap-night for Ae. vexans, 2.12 for Cx. pipiens, and 1.23 for Cx. restuans. Statistical analysis of the considerable temporal variability in species-specific abundances indicated that precipitation and relative humidity 1 wk prior were significantly positively associated with Ae. vexans, whereas elevated maximum temperature had a negative effect during summer. Cx. pipiens abundance was positively influenced by the preceding minimum temperature in the early season but negatively associated with precipitation during summer and with maximum temperature in July and August. Cx. restuans showed the least weather association, with only relative humidity 2-24 d prior being linked positively during late spring-early summer. The recently developed analytical method applied in this study could enhance our understanding of the influences of weather variability on mosquito population dynamics.

Landscape and Local Correlates of Bee Abundance and Species Richness in Urban Gardens.

PubMed

Quistberg, Robyn D; Bichier, Peter; Philpott, Stacy M

2016-03-31

Urban gardens may preserve biodiversity as urban population densities increase, but this strongly depends on the characteristics of the gardens and the landscapes in which they are embedded. We investigated whether local and landscape characteristics are important correlates of bee (Hymenoptera: Apiformes) abundance and species richness in urban community gardens. We worked in 19 gardens in the California central coast and sampled bees with aerial nets and pan traps. We measured local characteristics (i.e., vegetation and ground cover) and used the USGS National Land Cover Database to classify the landscape surrounding our garden study sites at 2 km scales. We classified bees according to nesting type (i.e., cavity, ground) and body size and determined which local and landscape characteristics correlate with bee community characteristics. We found 55 bee species. One landscape and several local factors correlated with differences in bee abundance and richness for all bees, cavity-nesting bees, ground-nesting bees, and different sized bees. Generally, bees were more abundant and species rich in bigger gardens, in gardens with higher floral abundance, less mulch cover, more bare ground, and with more grass. Medium bees were less abundant in sites surrounded by more medium intensity developed land within 2 km. The fact that local factors were generally more important drivers of bee abundance and richness indicates a potential for gardeners to promote bee conservation by altering local management practices. In particular, increasing floral abundance, decreasing use of mulch, and providing bare ground may promote bees in urban gardens. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Chemical Evolution of the Bootes I Ultra-faint Dwarf Galaxy

NASA Astrophysics Data System (ADS)

Frebel, Anna; Norris, John E.; Gilmore, Gerard; Wyse, Rosemary F. G.

2016-08-01

We present chemical abundance measurements of two metal-poor red giant stars in the ultra-faint dwarf galaxy Boötes I, based on Magellan/MIKE high-resolution spectra. For Boo-980, with {{[Fe/H]}}=-3.1, we present the first elemental abundance measurements, while Boo-127, with {{[Fe/H]}}=-2.0, shows abundances in good agreement with previous measurements. Light and iron-peak element abundance ratios in the two Boötes I stars, as well as those of most other Boötes I members, collected from the literature, closely resemble those of regular metal-poor halo stars. Neutron-capture element abundances Sr and Ba are systematically lower than the main halo trend and also show a significant abundance spread. Overall, this is similar to what has been found for other ultra-faint dwarf galaxies. We apply corrections to the carbon abundances (commensurate with stellar evolutionary status) of the entire sample and find 21% of stars to be carbon-enhanced metal-poor (CEMP) stars, compared to 13% without using the carbon correction. We reassess the metallicity distribution functions for the CEMP stars and non-CEMP stars, and confirm earlier claims that CEMP stars might belong to a different, earlier population. Applying a set of abundance criteria to test to what extent Boötes I could be a surviving first galaxy suggests that it is one of the earliest assembled systems that perhaps received gas from accretion from other clouds in the system, or from swallowing a first galaxy or building block type object. This resulted in the two stellar populations observable today. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Modeling the winter-to-summer transition of prokaryotic and viral abundance in the Arctic Ocean.

PubMed

Winter, Christian; Payet, Jérôme P; Suttle, Curtis A

2012-01-01

One of the challenges in oceanography is to understand the influence of environmental factors on the abundances of prokaryotes and viruses. Generally, conventional statistical methods resolve trends well, but more complex relationships are difficult to explore. In such cases, Artificial Neural Networks (ANNs) offer an alternative way for data analysis. Here, we developed ANN-based models of prokaryotic and viral abundances in the Arctic Ocean. The models were used to identify the best predictors for prokaryotic and viral abundances including cytometrically-distinguishable populations of prokaryotes (high and low nucleic acid cells) and viruses (high- and low-fluorescent viruses) among salinity, temperature, depth, day length, and the concentration of Chlorophyll-a. The best performing ANNs to model the abundances of high and low nucleic acid cells used temperature and Chl-a as input parameters, while the abundances of high- and low-fluorescent viruses used depth, Chl-a, and day length as input parameters. Decreasing viral abundance with increasing depth and decreasing system productivity was captured well by the ANNs. Despite identifying the same predictors for the two populations of prokaryotes and viruses, respectively, the structure of the best performing ANNs differed between high and low nucleic acid cells and between high- and low-fluorescent viruses. Also, the two prokaryotic and viral groups responded differently to changes in the predictor parameters; hence, the cytometric distinction between these populations is ecologically relevant. The models imply that temperature is the main factor explaining most of the variation in the abundances of high nucleic acid cells and total prokaryotes and that the mechanisms governing the reaction to changes in the environment are distinctly different among the prokaryotic and viral populations.

Modeling the Winter–to–Summer Transition of Prokaryotic and Viral Abundance in the Arctic Ocean

PubMed Central

Winter, Christian; Payet, Jérôme P.; Suttle, Curtis A.

2012-01-01

One of the challenges in oceanography is to understand the influence of environmental factors on the abundances of prokaryotes and viruses. Generally, conventional statistical methods resolve trends well, but more complex relationships are difficult to explore. In such cases, Artificial Neural Networks (ANNs) offer an alternative way for data analysis. Here, we developed ANN-based models of prokaryotic and viral abundances in the Arctic Ocean. The models were used to identify the best predictors for prokaryotic and viral abundances including cytometrically-distinguishable populations of prokaryotes (high and low nucleic acid cells) and viruses (high- and low-fluorescent viruses) among salinity, temperature, depth, day length, and the concentration of Chlorophyll-a. The best performing ANNs to model the abundances of high and low nucleic acid cells used temperature and Chl-a as input parameters, while the abundances of high- and low-fluorescent viruses used depth, Chl-a, and day length as input parameters. Decreasing viral abundance with increasing depth and decreasing system productivity was captured well by the ANNs. Despite identifying the same predictors for the two populations of prokaryotes and viruses, respectively, the structure of the best performing ANNs differed between high and low nucleic acid cells and between high- and low-fluorescent viruses. Also, the two prokaryotic and viral groups responded differently to changes in the predictor parameters; hence, the cytometric distinction between these populations is ecologically relevant. The models imply that temperature is the main factor explaining most of the variation in the abundances of high nucleic acid cells and total prokaryotes and that the mechanisms governing the reaction to changes in the environment are distinctly different among the prokaryotic and viral populations. PMID:23285186

Gas-Grain Models for Interstellar Anion Chemistry

NASA Technical Reports Server (NTRS)

Cordiner, M. A.; Charnely, S. B.

2012-01-01

Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

Long-term (1993-2013) changes in macrozooplankton off the Western Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Steinberg, Deborah K.; Ruck, Kate E.; Gleiber, Miram R.; Garzio, Lori M.; Cope, Joseph S.; Bernard, Kim S.; Stammerjohn, Sharon E.; Schofield, Oscar M. E.; Quetin, Langdon B.; Ross, Robin M.

2015-07-01

The Western Antarctic Peninsula (WAP) is one of the most rapidly warming regions on Earth, and where a high apex predator biomass is supported in large part by macrozooplankton. We examined trends in summer (January-February) abundance of major taxa of macrozooplankton along the WAP over two decades (1993-2013) and their relationship with environmental parameters (sea ice, atmospheric climate indices, sea surface temperature, and phytoplankton biomass and productivity). Macrozooplankton were collected from the top 120 m of the water column in a mid-Peninsula study region divided into latitudinal (North, South, and Far South) and cross-shelf (coastal, shelf, slope) sub-regions. Trends for krill species included a 5-year cycle in abundance peaks (positive anomalies) for Euphausia superba, but no directional long-term trend, and an increase in Thysanoessa macrura in the North; variability in both species was strongly influenced by primary production 2-years prior. E. crystallorophias abundance was best explained by the Southern Annular Mode (SAM) and Multivariate El Niño Southern Oscillation Index (MEI), and was more abundant in higher ice conditions. The salp Salpa thompsoni and thecosome pteropod Limacina helicina cycled between negative and positive anomalies in the North, but showed increasing positive anomalies in the South over time. Variation in salp and pteropod abundance was best explained by SAM and the MEI, respectively, and both species were more abundant in lower ice conditions. There was a long-term increase in some carnivorous gelatinous zooplankton (polychaete worm Tomopteris spp.) and amphipods. Abundance of Pseudosagitta spp. chaetognaths was closely related to SAM, with higher abundance tied to lower ice conditions. Long-term changes and sub-decadal cycles of WAP macrozooplankton community composition may affect energy transfer to higher trophic levels, and alter biogeochemical cycling in this seasonally productive and sensitive polar ecosystem.

Covariation of Peptide Abundances Accurately Reflects Protein Concentration Differences*

PubMed Central

Pirmoradian, Mohammad

2017-01-01

Most implementations of mass spectrometry-based proteomics involve enzymatic digestion of proteins, expanding the analysis to multiple proteolytic peptides for each protein. Currently, there is no consensus of how to summarize peptides' abundances to protein concentrations, and such efforts are complicated by the fact that error control normally is applied to the identification process, and do not directly control errors linking peptide abundance measures to protein concentration. Peptides resulting from suboptimal digestion or being partially modified are not representative of the protein concentration. Without a mechanism to remove such unrepresentative peptides, their abundance adversely impacts the estimation of their protein's concentration. Here, we present a relative quantification approach, Diffacto, that applies factor analysis to extract the covariation of peptides' abundances. The method enables a weighted geometrical average summarization and automatic elimination of incoherent peptides. We demonstrate, based on a set of controlled label-free experiments using standard mixtures of proteins, that the covariation structure extracted by the factor analysis accurately reflects protein concentrations. In the 1% peptide-spectrum match-level FDR data set, as many as 11% of the peptides have abundance differences incoherent with the other peptides attributed to the same protein. If not controlled, such contradicting peptide abundance have a severe impact on protein quantifications. When adding the quantities of each protein's three most abundant peptides, we note as many as 14% of the proteins being estimated as having a negative correlation with their actual concentration differences between samples. Diffacto reduced the amount of such obviously incorrectly quantified proteins to 1.6%. Furthermore, by analyzing clinical data sets from two breast cancer studies, our method revealed the persistent proteomic signatures linked to three subtypes of breast cancer. We conclude that Diffacto can facilitate the interpretation and enhance the utility of most types of proteomics data. PMID:28302922