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An evaluation of Mg/Ca, Sr/Ca, and Ba/Ca ratios as environmental proxies in aragonite bivalve shells ArchiMer
Poulain, C.; Gillikin, D. P.; Thebault, Julien; Munaron, Jean-marie; Bohn, M; Robert, Rene; Paulet, Yves-marie; Lorrain, Anne.
The influence of salinity and water chemistry on Mg/Ca, Sr/Ca and Ba/Ca ratios in the aragonitic shells of the Manila clam were investigated. Clams were reared at constant temperature (20 °C) under different controlled conditions of salinity, commonly encountered in their natural habitat. Clams were held in three tanks with a constant salinity of 35 for the first 35 days and then two tanks were changed to lower salinities (20 and 28) for the next 29 days. Individual shell Mg/Ca, Sr/Ca and Ba/Ca ratios were studied through time. Despite stable conditions (temperature, salinity, and Mg/Cawater) for clams reared at salinity 35 during the experiment, Mg/Ca shell ratios increased through the time. Moreover the salinity decrease at t35 slowed the increase of...
Tipo: Text Palavras-chave: Ruditapes philippinarum; Aragonite; Sclerochronology; Bivalved mollusk; Trace element; Proxy.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00245/35649/34158.pdf
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Experimental shift of diet and DIC stable carbon isotopes: Influence on shell delta C-13 values in the Manila clam Ruditapes philippinarum ArchiMer
Poulain, C.; Lorrain, Anne; Mas, R.; Gillikin, D. P.; Dehairs, F.; Robert, Rene; Paulet, Yves-marie.
The influences of diet and seawater dissolved inorganic carbon (DIC) on the carbon isotope composition of shell aragonite (Cinched in the Manila clam Ruditapes philippinarum reared under laboratory conditions were investigated. Clams were exposed to two successive negative carbon isotope shifts: a first shift in diet (delta C-13(phytoplankton)) and a second shift, 35 days later, in DIC (delta C-13(DIC)). Both successive shifts induced a decrease in delta C-13(shell). These results are the first to experimentally confirm an incorporation of respired carbon derived from food and carbon from DIC into shell carbonate of adult bivalves. Skeletal delta C-13 responded to changes in the delta C-13 of both diet and DIC in less than 7 days. Consequently, proxies...
Tipo: Text Palavras-chave: Delta C-13(shell); DIC; Salinity; Metabolic carbon; Ruditapes philippinarum; Estuarine water; Proxy.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00003/11443/8001.pdf
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Improving Agronomic Structure in Econometric Models of Climate Change Impacts AgEcon
Ortiz-Bobea, Ariel.
Economists are relying on agronomic concepts to construct weather or climate independent variables and improve the reliability and efficiency of econometric models of climate change impact on U.S. agriculture. The use of cumulative heat measures in agronomy (growing degree-days), has recently served as a basis for the introduction of plurimonthly calendar heat variables in these models. However, season-long weather conditions seem at odds with conventional agronomic wisdom that emphasizes crucial differences in crop stage sensitivity to environmental stress. In this paper I show that weather variables matched to key corn development stages provide an enhanced and more stable fit than their calendar counterparts. More importantly, the proposed...
Tipo: Conference Paper or Presentation Palavras-chave: Agriculture; Climate change; Corn; Degree-days; Phenology; Proxy; Yield; Production Economics; Research Methods/ Statistical Methods; Resource /Energy Economics and Policy; Q54; C23.
Ano: 2011 URL: http://purl.umn.edu/103656
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Occurrence of annual growth rings in Rhizophora mangle in a region with low climate seasonality Anais da ABC (AABC)
SOUZA,BRUNNA T.; ESTRADA,GUSTAVO C.D.; SOARES,MÁRIO L.G.; CALLADO,CÁTIA H..
ABSTRACT The formation of annual growth rings has been confirmed for several mangrove species in the last decade, among which is the Rhizophora mangle. However, the record of annual rings for this species was made in a region with high hydric seasonality, a widely recognized induction factor of annual rings in tropical species. In this sense, the present study aimed to verify the occurrence of annual growth rings in R. mangle in the mangroves of Guaratiba (Rio de Janeiro, Southeastern Brazil), a region with low hydric seasonality. For this purpose, the crossdating technique was applied in ten trees collected with known age (seven years). The growth rings are characterized by alternating layers of low vessel density (earlywood) and high vessel density...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Growth rings; Dendrochronology; Mangrove; Dendroecology; Proxy.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000200517
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Phenotypic plasticity and fitness in egg parasitoids Neotropical Entomology
Boivin,Guy.
Several proxies can be used to estimate the fitness of egg parasitoids: size, longevity, fecundity, mating ability and vagility. All these proxies are positively correlated with the lifetime fitness gain of an individual. However, the phenotypic plasticity, which is the ability of a genotype to produce distinct phenotypes depending on environmental conditions, may alter the value of these proxies. Host related factors (host species and quality), competition and duration of development will influence the proxies expressed by a given phenotype. When the phenotype is modified by the temperature at which an individual develops, the resulting phenotype will vary based on the life history strategy of the parasitoid. While in koinobiont species an increase in...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Fitness; Proxy; Reproduction; Longevity; Phenotype.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2010000400001
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The Arctic sea ice biomarker IP25: a review of current understanding, recommendations for future research and applications in palaeo sea ice reconstructions ArchiMer
Belt, Simon T.; Mueller, Juliane.
In recent years, a novel proxy for the past occurrence of Arctic sea ice has been proposed that is based on the variable marine sedimentary abundance of an organic geochemical lipid derived from sea ice diatoms in the spring. This lipid, termed IP25 (Ice Proxy with 25 carbon atoms), is a highly branched isoprenoid mono-unsaturated alkene that appears to be sufficiently stable in sediments to permit meaningful palaeo sea ice reconstructions to be carried out over short- to long-term timescales. Since the first proposed use of IP25 as a proxy for palaeo sea ice by Belt et al. (2007), a number of laboratories have measured this biomarker in Arctic sediments and it is anticipated that research activity in this area will increase further in the future. The...
Tipo: Text Palavras-chave: Sea ice; Arctic; Proxy; IP25; Biomarker; Palaeoclimate.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00263/37473/36537.pdf
Registros recuperados: 6
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