Search results for "Isotope analysis"

Responses of zooplankton to cane sugar additions to a small humic lake, Alinen Mustajärvi

2010

The response to projected increase in dissolved organic carbon (DOC) loading to boreal lakes is being studied in lake Alinen Mustajärvi, a small humic lake in southern Finland, where labile DOC concentration has been artificially increased during 2008 and 2009 by monthly additions of cane sugar. As part of this wider project, in this thesis the responses of the zooplankton community to cane sugar addition were studied. Zooplankton samples were collected monthly in the ice-free periods of 2007, 2008 and 2009 and the mean densities and mean carbon biomasses of rotifers and crustacean zooplankton (cladocerans and copepods) were calculated. Stable isotope analyses (δ13C and δ15N) were made for …

Huit objets de cuivre et de bronze du piémont pyrénéen oriental : analyse croisée typologique et métallique

2015

Cet article porte sur huit pièces à base de cuivre – deux haches plates et six poignards – provenant de la zone sous-pyrénéenne orientale (Corbières, Haute Vallée de l’Aude, Pays d’OImes), dans les départements de l’Aude et de l’Ariège de l’Est (région de Lavelanet). Elles sont décrites et replacées dans leur contexte typochronologique, alors que les aspects technoéconomiques sont envisagés via la composition métallique (composition élémentaire et rapports isotopiques du plomb). Cinq objets en cuivre – deux haches et trois poignards – sont attribués au Chalcolithique. L’une des haches se rapproche des types nord-ibériques et son importation depuis cette région est suggérée par les analyses …

Lake size and fish diversity determine resource use and trophic position of a top predator in high-latitude lakes

2015

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes…

The variable position of Arctic charr (Salvelinus alpinus (L.)) in subarctic lake food webs

2013

Benthic foodweb structure in a large shallow lake studied by stable isotope analysis

2014

The benthic foodweb structure of Lake Võrtsjärv, a large (270 km2), shallow, and turbid Estonian lake, was evaluated based on C and N stable-isotope signatures (δ13C, δ15N). Variation in δ13C between sampling sites was not related to site proximity to the littoral zone or the more vegetated southern part of the lake, but rather appeared to be influenced by in-situ site peculiarities. δ13C was stable temporally and between functional feeding groups, a result implying that the whole benthic food web of the lake relies largely on the same C source admixture, essentially particulate organic matter (POM). Thus, the foodweb composition of Lake Võrtsjärv is remarkably homogeneous given the lake’s …

Dependence of Arctic char (Salvelinus alpinus L.) on littoral and pelagic energy sources in a subarctic lake, Saanajärvi

2007

Carbon cycle and sea-water palaeotemperature evolution at the Middle-Late Jurassic transition, eastern Paris Basin (France).

2014

14 pages; International audience; A very high-resolution carbon and oxygen stable isotope analysis (bulk-carbonate) of a biostratigraphically well-constrained Callovian-Oxfordian series is provided here for the first time. The homogeneity of the clayey series and the weak diagenetic alteration allow the isotopic signal variations to be considered as primary in origin. A prominent and brief negative excursion in the δ13C curve (−2‰), occurring at the start of the Middle Callovian (Jason Zone - Obductum Subzone) and correlated regionally, suggests a possible methane release. The increasing δ13C values thereafter up to the Early Oxfordian, concomitant with a warming episode, highlight the buri…