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Recent studies suggest that stable hydrogen isotope ratios (δD) of fish can be used to track their watershed origin and the relative contributions of source material. Both applications assume that there is no metabolic or trophic effect on tissue δD. We studied the local variation of δD values in four fish species of contrasting size and feeding habits in an isotopically homogenous reservoir (Flix, Spain). Other isotopic values (δ15N, δ[sup.13]C) and trace metal content were measured as indicators of trophic and bioaccumulation patterns. In addition, isotopic values (δD, δ[sup.15]N, δ[sup.13]C) of other food web components were measured for comparison. Muscle δD values differed greatly among fish species: European catfish, Silurus glanis (-131 ‰); common carp, Cyprinus carpio (-141 ‰); rudd, Scardinius erythrophthalmus (-158 ‰); and roach, Rutilus rutilus (-163 ‰). The influence of fish size and trophic position affected the fish δD values. Possible mechanisms that drive δD variation among fish might be a metabolic effect and (or) the compounding effect of ambient water δD on exchangeable H at each trophic stage. Our findings showed that size and feeding habits are factors that should be controlled when tracing origins of fish or their dependence on nutrient inputs using δD measurements. Des etudes recentes indiquent que les rapports d'isotopes stables d'hydrogene (δD) des poissons peuvent servir a retracer leur bassin versant d'origine et les contributions relatives des materiaux sources. Ces deux utilisations presupposent qu'il n'y a pas d'effet metabolique ou trophique sur le δD des tissus. Nous avons etudie la variation locale des valeurs de δD chez quatre especes de poissons de tailles et d'habitudes alimentaires tres differentes dans un reservoir homogene par ses isotopes (Flix, Espagne). Nous avons determine les autres valeurs isotopiques (δ15N, δ[sup.13]C) et les concentrations des metaux en trace comme indicateurs des patrons trophiques et des patrons de bioconcentration. Nous avons, de plus, mesure les valeurs isotopiques (δD, δ[sup.15]N, δ[sup.13]C) des autres composantes du reseau alimentaire pour etablir des comparaisons. Les valeurs de δD du muscle varient considerablement d' une espece de poisson a une autre : le silure glane, Silurus glanis (-131 ‰), la carpe commune, Cyprinus carpio (-141 ‰), le rotengle, Scardinius erythrophthalmus (-158 ‰) et le gardon, Rutilus rutilus (-163 ‰). La taille du poisson et sa position trophique affectent les valeurs de δD du poisson. Les mecanismes explicatifs possibles de la variation de δD chez les poissons pourraient inclure un effet metabolique et (ou) l'effet cumulatif du δD de l'eau ambiante sur l'H echangeable a chaque stade trophique. Nos resultats demontrent qu'il faut tenir compte de la taille et des habitudes alimentaires pour retracer a l'aide de mesures de δD les origines des poissons ou leur dependance des apports de nutriments. [Traduit par la Redaction], Introduction Stable isotopes are currently broadly applied in ecological studies. Measurements of stable isotopes of carbon (δ[sup.13]C), nitrogen (δ[sup.15]N), and sulfur (δ[sup.34]S) are used as indicators of trophic level and [...]

Stable hydrogen isotopes (δD) can be a powerful tool for estimating the large-scale movements of animals, but the cause and extent of isotopic variation within animal tissues remain poorly understood. Here, we simultaneously examined three hypotheses to explain δD variation in the blood (δ[D.sub.B]) of nestling Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) from a single nest-box population in southern Ontario, Canada: (1) microgeographic and (or) temporal variation in δD of local diet, (2) potential evaporation of protium resulting from variation in nest-box temperature, and (3) differences in body size resulting in higher rates of water loss and isotope fractionation in larger birds. δ[D.sub.B] ranged from -128% to -94%, with a mean ± SD of -113 ‰ ± 7 ‰. Nest-box temperatures ranged from 21.5 to 38°C immediately prior to blood collection. A general linear mixed-effects model explained 80% of the variation in δ[D.sub.B] and provided evidence that δD values in prey, maximum temperature 1 day prior to blood collection, and body size were all significant predictors of δ[D.sub.B]. Our results suggest that isotopic variation in individuals and local populations arises from a combination of physiological factors and local environmental variation. To gain a complete understanding of how δD values can be used to estimate animal movements, additional work is needed to determine how these factors influence other tissues, such as metabolically inert feathers, and animals of different age classes. Les isotopes stables d'hydrogene (δD) peuvent etre de puissants outils pour estimer les deplacements a grande echelle des animaux, mais la cause et l'etendue de la variation isotopique dans les tissus animaux restent mal comprises. Nous examinons ici simultanement trois hypotheses pour expliquer la variation de δD dans le sang (δ[D.sub.B]) d'hirondelles bicolores (Tachycineta bicolor (Vieillot, 1808)) au nid dans une seule population de pondoirs du sud de l'Ontario, Canada, soit (1) une variation micro-geographique et(ou) temporelle de δD du regime alimentaire local, (2) une evaporation potentielle du protium due a la variation de la temperature dans le pondoir et (3) des differences de taille corporelle entranant des taux plus eleves de perte d'eau et de fractionnation des isotopes chez les oiseaux plus grands. Les valeurs de δ[D.sub.B] varient de -128 ‰ a -94 ‰ avec une moyenne ± ET de -113 ‰ ± 7 ‰. Les temperatures des pondoirs variaient de 21,5 a 38°C immediatement avant le prelevement sanguin. Un modele lineaire general d'effets mixtes explique 80 % de la variation de δ[D.sub.B] et donne des indications que la valeur de δD des proies, la temperature maximale un jour avant le prelevement sanguin et la taille corporelle sont toutes des variables explicatives significatives de δ[D.sub.B]. Nos resultats indiquent que la variation isotopique chez les individus et les populations locales est causee par une combinaison de facteurs physiologiques et de variation locale de l'environnement. Afin d'obtenir une comprehension globale de la maniere dont les valeurs de δD peuvent servir a estimer les deplacements des animaux, il faudra faire des travaux additionnels pour determiner comment ces facteurs influencent les autres tissus, tels que les plumes qui sont metaboliquement inertes, ainsi que les animaux des differentes classes d'age. [Traduit par la Redaction], Introduction Stable hydrogen isotope (δD) measurements have been used to estimate movements of organisms across broad spatial scales (Hobson and Wassenaar 2008). Animals incorporate hydrogen into their tissues from the [...]

Evaporation and groundwater fluxes are thought to regulate hydrologic variability in lakes of the northern Great Plains, but little is known of how the relative importance of these processes may vary in time or space. To address this issue, we measured the isotopic composition of water ([[delta].sup.18]]O, [[delta].sup.2]H) from 70 closed-basin lakes in southern Saskatchewan, Canada. All lakes occupied endorheic basins along a long gradient of salinity (0.2-115 g total dissolved solids [L.sup.-1]). Lakes exhibited synchronous seasonal changes in salinity (synchrony, S = 0.78) and [[delta].sup.18]]O (S = 0.84) during the dry summer of 2003 (~195 mm rain), whereas coherence was reduced to 0.56 and 0.22, respectively, during the wet summer of 2004 ~295 mm rain). However, despite evaporative enrichment of isotopic ratios during dry summers, hydrologic balances were regulated mainly by changes in water inflow (I) rather than evaporation (E) in both wet and dry years, with particularly strong influence of inflow (lowest E : I ratio) in dry southwestern regions. Analysis of isotopic composition also identified winter precipitation or groundwater as the most influential source of water to most lakes, despite only ~30% of annual precipitation being delivered during winter. Therefore, although seasonal variability in lake chemistry was influenced by evaporation during summer, long-term mean chemical characteristics of prairie lakes were regulated mainly by changes in winter precipitation or groundwater influx.

We inferred climate change through the Pleistocene-Holocene transition from [[delta].sup.13]C and [delta]D values of bat guano deposited from 14.5 to 6.5 ka (calendar ka) in Bat Cave, Grand Canyon, Arizona. The [[delta].sup.13]C and [delta]D values generally covaried, indicating that regional late Pleistocene climate was relatively cool and wet, and early Holocene climate gradually became warmer with increased summer precipitation until ca. 9 ka, at which time the onset of modern North American Monsoon-like conditions occurred. During the Younger Dryas event, [[delta].sup.13]C values decreased, whereas [delta]D values increased, indicating a cool and possibly drier period. We also observed a distinct isotopic anomaly during the 8.2 ka event, at which time both [[delta].sup.13]C and [delta]D values decreased. The [[delta].sup.13]C values abruptly increased at 8.0 ka, suggesting a rapid change in atmospheric circulation and greater influence from convective storms originating from the south. Deposits of bat guano represent a largely untapped source of paleoenvironmental information that can provide continuous and long-term continental archives of environmental change. Keywords: arid, precipitation, vegetation, paleoclimate, North American Monsoon.

Measurement of stable-hydrogen isotopes ([delta]D) in feathers of migrating birds can provide information on where feathers were grown in North America, at least to an approximate band of latitude. This approach has greatly increased our ability to investigate aspects of avian migration and stopover ecology, since origins of unmarked individuals at migration stopover sites can be estimated for the first time. However, few studies have explored the power of combining isotope measurements with geographic information system (GIS) methods. We measured [delta]D values in feathers of hatching-year (HY) Swainson's Thrushes (Catharus ustulatus; n = 60), Wood Thrushes (Hylociehla mustelina; n = 113), and Gray Catbirds (Dumetella carolinensis; n = 158) at Ft. Morgan Peninsula, Alabama (30[degrees]10'N, 88[degrees]00'W), a migration stopover site along the Gulf coast. By applying an elevation-corrected hydrogen isotope basemap for birds in North America, we derived a GIS surface depicting expected feather [delta]D values across the continent. We then used GIS to constrain the possible origins of the sampled populations by considering only values falling within the North American breeding ranges of the species. We depicted likely origins of migrating birds by the 50% and 75% tolerance limits of the data. Our GIS analysis indicated that our captured populations represented much-reduced regions of possible origin based on the North American breeding distributions. Gradients in abundance data from the North American Breeding Bird Survey (BBS) allowed us to further narrow possible origins within isotopic boundaries for Wood Thrushes and Gray Catbirds. This exercise provided a means by which priority regions and habitats could be assessed at large continental scales based on actual productivity. We suggest the combination of isotopic and GIS tools provides a powerful means to derive conservation priorities and to investigate key factors involved in the ecology of avian migration and stopover. Key words: deuterium, geographic information systems, migratory connectivity, stable isotopes, stopover. La medicion de isotopos estables de hidrogeno ([delta]D) en las plumas de las aves migratorias puede proveer informacion importante acerca del lugar geografico en Norteamerica donde crecieron las plumas, o por lo menos aproximar la localizacion dentro de una banda latitudinal especifica. Esta tecnica ha aumentado considerablemente nuestra capacidad de investigar aspectos de la migracion y la ecologia de las paradas migratorias de las aves, debido a que por primera vez es posible determinar el origen de individuos no marcados en sitios de paradas migratorias. Sin embargo, pocos estudios han explorado el poder de combinar medidas de isotopos con metodos de sistemas de informacion geografica (SIG). En este estudio, medimos los valores de [delta]D en plumas de individuos de las especies Catharus ustulatus (n = 60), Hylocichla mustelina (n = 113) y Dumetella carolinensis (n = 158) en su ano de eclosion en la peninsula de Ft. Morgan, Alabama (30[degrees]10'N, 88[degrees]00'W), un sitio de paradas migratorias en la costa del Golfo. Mediante la aplicacion de un mapa base de isotopos de hidrogeno corregido por la elevacion para las aves de Norteamerica y utilizando un SIG, derivamos una superficie que representa los valores de [delta]D esperados para plumas en todo el continente. Luego utilizamos el SIG para restringir los posibles origenes de la poblacion muestreada, considerando solo los valores que cayeran dentro de los rangos de distribucion reproductiva de las especies en Norteamerica. Representamos los posibles origenes de las aves migratorias mediante los limites de tolerancia de los datos del 50% y del 75%. Nuestro analisis de SIG indico que las poblaciones capturadas representaban distribuciones mucho mas reducidas con base en las distribuciones reproductivas de las aves de Norteamerica. Datos de gradientes de abundancia provenientes de la base de datos de conteos de aves reproductivas de Norteamerica nos permitieron aproximar aun mas los posibles origenes dentro de los limites sugeridos por los isotopos para H. mustelina y D. carolinensis. Este ejercicio represento un medio para determinar regiones y habitats prioritarios para la conservacion a una escala continental con base en la productividad real de las regiones. Sugerimos que el uso combinado de tecnicas de isotopos y SIG representa un medio poderoso para determinar prioridades para la conservacion, y para investigar factores clave sobre la ecologia de la migracion y las paradas migratorias.

Abstract: Stable hydrogen isotope (δD) measurements of bird feathers can reveal approximate North American latitudes where feathers were grown by linking feather δD values to well-defined geographic patterns in δD [...]

Stable isotopes were used in a study to differentiate birds from major western North America production areas in order to provide a means of elucidating the natal origins of waterfowl. Geographic patterns in feather isotopes were found to be related to natural gradients by biogeochemical cycles and anthropogenic factors such as agrochemical usage.

Here we describe an on-line method for measuring b37CI values of chloride bearing salts, waters, and organic materials using multicollector continuous-flow isotope ratio mass spectrometry (CF-IRMS). Pure AgCl quantitatively derived from total Cl in water, inorganic Cl salts, and biological samples was reacted with iodomethane in evacuated 10-mL stopper sealed glass vials to produce methyl chloride gas. A GV Instruments Multicollector CF-IRMS with C[H.sub.3]Cl optimized collector geometry was modified to accommodate a headspace single-sample gas injection port prior to a GC column. The GC column was a 2-m Porapak-Q packed column held at 160[degrees]C. The resolved sample C[H.sub.3]Cl was introduced to the IRMS source in a helium stream via an open split. [[delta].sup.37]Cl values were calculated by measurement of C[H.sub.3]Cl at m/z 52/50 and by comparison to a reference pulse of C[H.sub.3]Cl calibrated to standard mean ocean chloride. Sample C[H.sub.3]Cl analysis time was ~6 min. Injections of 40 [micro]L of pure C[H.sub.3]Cl gas yielded a repeatability ([+ or -] SD) of [+ or -] 0.06 [per thousand] for [[delta].sup.37]Cl (n = 10). Combined GC and IRMS source linearity for C[H.sub.3]Cl was

The measurement of the abundance of naturally occurring deuterium ([delta]D) in feathers grown in North America can provide geographical information on location where the feather was grown. Previously, we used this technique to link populations of Bicknell's Thrush (Catharus bicknelli) breeding in northeastern North America (to 46[degrees]N) with wintering grounds in the Dominican Republic. That study indicated the presence of a subpopulation of wintering birds with more depleted feather [delta]D values than those measured on their known breeding grounds. This suggested either a more northerly or a higher altitude breeding source population than previously measured. We located two populations of Bicknell's Thrush in Quebec, Canada, at Mine Madeleine (49[degrees]N) and at Mont Gosford (45[degrees]N). The Mine Madeleine birds had feather [delta]D values overlapping those of the unidentified subpopulation found wintering in the Dominican Republic. At Mont Gosford, hatch-year birds were more depleted in their feather [delta]D values than after-second-year birds suggesting their more northerly origins and capture during the early fall migration period. Our study demonstrates how the stable-isotope approach can be used to document connectivity between breeding and wintering populations of migratory birds. Key words: Catharus bicknellii, deuterium, migratory connectivity, stable isotopes.

Understanding movements of individual birds between breeding sites (breeding dispersal) or between natal sites and the site of first breeding (natal dispersal) is crucial to the modeling of population dynamics. Unfortunately, these aspects of demography are poorly understood for avian species in general, and for migratory songbirds in particular. This is because it is often impossible to sample broadly enough to relocate marked birds that have moved. We used stable-hydrogen ([delta]D) and carbon ([delta][sup.13]C) isotope analyses of the feathers of 139 American Redstarts (Setophaga ruticilla) and 193 Ovenbirds (Seiurus aurocapillus) to evaluate evidence for individuals molting feathers at locations other than their breeding sites from the previous year. We sampled outer rectrices from breeding populations at three extensive boreal forest sites (Prince Albert National Park and Duck Mountain, Saskatchewan. and Lac La Biche, Alberta) and at three isolated forest tracts (Cypress Hills, and Moose Mountain, Saskatchewan, and Turtle Mountain, Manitoba) in western Canada. Based on outlier analysis of [delta]D measurements, we found evidence for long-distance dispersal ranging from 0-29% of individuals. For both species, second-year birds had higher variance in [delta]D values suggesting they had a higher probability of originating from elsewhere compared to after-second-year birds. Key words: carbon-13, deuterium, dispersal, feathers, philopatry, source-sink populations, stable isotopes.

Feathers from flightless mallard ducklings are sampled across western Canada for nitrogen levels. High levels of anthropogenic nitrogen are associated with areas of greater agricultural activity.

Results suggest that using stable-carbon and hydrogen isotope ratios are a reliable means of determining blackbird breeding origins along a latitudinal transect from Louisiana to Saskatchewan. The method was applied to the outer primary feathers, which determined dietary intake of carbon and precipitation exposure.

Few studies have used the stable isotopic composition of O(sub 2) as a tracer of gas transport or biogeochemical processes in environmental research. Here we demonstrate field sampling techniques for gaseous and dissolved O(sub 2) and describe an analytical method for measuring (delta)(super 18)O and (delta)(super 17)O values of O(sub 2) in air, soil gas, and water samples using continuous-flow isotope-ratio mass spectrometry (CF-IRMS). A Micromass CF-IRMS was altered to accommodate a sample gas injection port prior to a CO(sub 2) and H(sub 2)O trap and GC column. The GC column was a l-m, 5-(Angstroms) molecular sieve column held at 35 degrees C. The resolved sample O(sub 2) was introduced to the IRMS via an open split. (delta)(super 18)O and (delta)(super 17)O values were determined by measurement of O(sub 2) isotopes at m/z 34/32 and 33/32 and comparison to a reference pulse of O(sub 2). Repeated injections of atmospheric oxygen yielded a repeatability (+/- SD) of +/- 0.17% for (delta)(super 18)O and +/- 0.5% for (delta)(super 17)O. IRMS source linearity was excellent for O(sub 2) over a sample size range of 60-400 (mu)L. The smallest sample for routine (delta)(super 18)O and (delta)(super 17)O determinations was approximately 80 (mu)L of )(sub 2), with a sample analysis time of 180 s. Preliminary results from a riverine and soil gas study illustrate natural oxygen isotope fractionation processes.

Despite considerable interest in using stable-hydrogen isotope ratio ([Delta]D) measurements in ecological research, it was previously unknown whether hydrogen derived from drinking water, in addition to that derived from diet, contributed to the nonexchangeable hydrogen in animal tissues. We raised four experimental groups of quail (Coturnix coturnix japonica) from hatch on two isotopically distinct diets (mean nonexchangeable [Delta]D: -146 and -60[per thousand], Vienna Standard Mean Ocean Water Standard) and drinking waters (mean [Delta]D: -130 and +196[per thousand], Vienna Standard Mean Ocean Water Standard). Here we show that both dietary and drinking water hydrogen are incorporated into nonexchangeable hydrogen in both metabolically active (i.e., muscle, liver, blood, fat) and inactive (i.e., feather, nail) tissues. Approximately 20% of hydrogen in metabolically active quail tissues and 26-32% of feathers and nail was derived from drinking water. Our findings suggest environmental interpretations of [Delta]D values from modern and fossil animal tissues may need to account for potentially large isotopic differences between drinking water and food and require a good understanding of the physiological ecology of study organisms.

Each year, millions of monarch butterflies from eastern North America migrate to overwinter in 10-13 discrete colonies located in the Oyamel forests of central Mexico. For decades efforts to track monarch migration have relied on observations and tag-recapture methods, culminating with the discovery of the wintering colonies in 1975. Monarch tag returns from Mexico, however, are few and primarily from two accessible colonies, and therefore tag-recapture techniques have not quantified natal origins or distinctiveness among monarch populations at wintering sites. Such information would be invaluable in the conservation of the monarch and its migration phenomenon since the wintering sites currently are threatened by habitat alteration. Here we show that stable hydrogen ([Delta]D) and carbon ([Delta]13C) isotope ratios of wintering monarchs can be used to evaluate natal origins on the summer breeding range. Stable-hydrogen and carbon isotopic values of 597 wintering monarchs from 13 wintering roost sites were compared with isotopic patterns measured in individuals at natal sites across their breeding range over a single migration cycle. We determined that all monarch wintering colonies were composed of individuals originating mainly from the Midwest, United States, thereby providing evidence for a panmictic model of wintering colony composition. However, two colonies showed more northerly origins, suggesting possible priority colonies for conservation efforts.

A combination of stable-isotope measurements of tissues representing different periods of dietary integration and body composition analyses was used to determine geospatial linkage of northern pintails breeding in Alaska. The results provide insight into the relationship among winter and spring location, distance traveled and arrival conditions.

Hunters in southern Alberta and Saskatchewan, Canada use a stable isotope featherprints to determine the geographic origins of northern pintail ducks shot. The results suggested that production of northern pintails on the Canadian Prairies might be significantly lower than predicted by the number of breeding birds and might be related to human-induced reductions in nest success because of agricultural practices.

Previous studies have shown that natural abundance of deuterium (D), and to a lesser extent [sup.13]C, in feathers of migrant songbirds in North America can be used to infer geographic origins of molt. We used that approach to investigate whether Bicknell's Thrush (Catharus bicknelli) populations could be segregated on the breeding grounds at six sites in eastern North America to evaluate contributions from the breeding areas to wintering populations. Further, we tested our isotopic model using feathers from hatching-year migrant Swainson's Thrush (Catharus ustulatus) and Gray-cheeked Thrush (Catharus minimus) moving through southern Manitoba and Ontario and found that [Delta]D values were consistent with northerly boreal forest natal sites in northwestern and central Canada. Despite a strong latitudinal gradient in [Delta]D of average growing season precipitation over the breeding range, we found considerable overlap in [Delta]D values of Bicknell's Thrush among all breeding sites. No strong pattern in [Delta][sup.3]C values of feathers with latitude was apparent. Nevertheless, the more negative [Delta]D values of feathers from wintering birds in the Dominican Republic compared to breeding area samples suggested that birds from more northerly locations in North America contributed to this population of wintering birds. High variance in feather [Delta]D values within breeding populations also suggested high natal dispersal, considerable movement of birds among island habitats on the breeding grounds, or both. Even higher variances in feather [Delta]D values from small study areas on the wintering grounds, compared to similar-sized areas in the breeding range, suggest that many different breeding populations mix in winter habitat. Received 1 November 1999, accepted 8 August 2000.

The stable-oxygen and -hydrogen isotopic values ([Delta]D, [[Delta].sup.18]O) of porewater in geologic media are commonly determined on water obtained by extraction techniques such as centrifugation, mechanical squeezing, vacuum heating and cryogenic microdistillation, and azeotropic distillation. Each of these techniques may cause isotopic fractionation as part the extraction process and each is laborious. Here we demonstrate a new approach to obtain automated, high-precision [Delta]D and [[Delta].sup.18]O measurements of porewater in geologic sediments by direct [H.sub.2]-- and [CO.sub.2]--porewater equilibration using a modified commercial [CO.sub.2]--water equilibrator. This technique provides an important and cost-effective improvement over current extraction methods, because many samples can be rapidly analyzed with minimal handling, thereby reducing errors and potential for isotopic fractionation. The precision and accuracy of direct [H.sub.2]-- and [CO.sub.2]--porewater equilibration is comparable to or better than current porewater extraction methods. Finally, the direct equilibration technique allows investigators to obtain high-resolution (cm scale) porewater [Delta]D and [[Delta].sup.18]O profiles using cores from individual boreholes, eliminating the need for costly piezometers or conventional porewater extractions.

Leonard I. Wassenaar [a] M. Jim Hendry [b] Abstract Due to extremely slow water recovery rates in aquitards and high contamination potential from sealing materials, installation of piezometers in aquitards [...]