Search results for "δ13C"
showing 10 items of 109 documents
An Empirical Evaluation of the Utility of Convex Hull and Standard Ellipse Areas for Assessing Population Niche Widths from Stable Isotope Data
2013
Stable isotope analyses are increasingly employed to characterise population niche widths. The convex hull area (TA) in a δ¹³C–δ¹⁵N biplot has been used as a measure of isotopic niche width, but concerns exist over its dependence on sample size and associated difficulties in among-population comparisons. Recently a more robust method was proposed for estimating and comparing isotopic niche widths using standard ellipse areas (SEA), but this approach has yet to be tested with empirical stable isotope data. The two methods measure different kind of isotopic niche areas, but both are now widely used to characterise isotopic niche widths of populations. We used simulated data and an extensive e…
Root growth and soil carbon turnover in Opuntia ficus-indica as affected by soil volume availability
2019
Abstract The aim of this study was to investigate the effect of soil volume restriction, i.e. root confinement, on below-and-above ground growth of cactus pear (Opuntia ficus-indica (L.) Mill) as well as the effect on root architecture and turnover, and soil carbon turnover. In May 2014, 1- year-old cladodes were planted in five different pots size (50, 33, 18, 9 and 5 L). Soil samples were collected from each pot and dried before SOC and δ13C determination. Roots of each plant were divided visually into three groups depending on their diameter, and then measured and weighed. Results indicated a significant effect of soil volume and sampling dates on total root length, root dry mass and δ13…
Carbon isotope composition of plant photosynthetic tissues reflects a Crassulacean Acid Metabolism (CAM) continuum in the majority of CAM lineages
2021
Abstract The stable carbon isotope composition of plant tissues, commonly expressed as δ13C, holds a wealth of information about photosynthetic pathway, water relations and stress physiology. Crassulacean acid metabolism (CAM) is a derived form of photosynthesis that allows plants to fix carbon at a higher water-use efficiency compared to the ancestral C3 photosynthesis. While the central carbon-fixing enzyme of C3 plants, Rubisco, strongly discriminates against the heavy 13C isotope, CAM is characterized by a dual use of Rubisco and the much less discriminating PEP carboxylase as carbon-fixing enzymes, causing the δ13C values of CAM plant tissues to be generally less negative than those fo…
Ecophysiological Modeling of Grapevine Water Stress in Burgundy Terroirs by a Machine-Learning Approach
2016
13 pages; International audience; In a climate change scenario, successful modeling of the relationships between plant-soil-meteorology is crucial for a sustainable agricultural production, especially for perennial crops. Grapevines (Vitis vinifera L. cv Chardonnay) located in eight experimental plots (Burgundy, France) along a hillslope were monitored weekly for 3 years for leaf water potentials, both at predawn (Ψpd) and at midday (Ψstem). The water stress experienced by grapevine was modeled as a function of meteorological data (minimum and maximum temperature, rainfall) and soil characteristics (soil texture, gravel content, slope) by a gradient boosting machine. Model performance was a…
Spatial variability of stable carbon and nitrogen isotope ratios in a Mediterranean coastal lagoon
2005
Exploring the trophic pathway of organic matter within the Mauguio lagoon (southern France, western Mediterranean), we found spatial differences in the isotopic composition (both δ13C and δ15N values) of organic matter sources (primary producers, particulate and sedimentary organic matter), which were mirrored in the upper trophic levels (invertebrates and fish). On average, δ13C was heavier by about 1.5–2‰ in the location under marine influence than in the sites influenced by freshwater discharge. The opposite trend was found for δ15N, which attained maximum values in the north-central zone influenced by freshwater delivery. For both C and N stable isotope ratios, the highest spatial varia…
Resilience of the seagrass Posidonia oceanica following pulse-type disturbance.
2020
Understanding the response of species to disturbance and the ability to recover is crucial for preventing their potential collapse and ecosystem phase shifts. Explosive submarine activity, occurring in shallow volcanic vents, can be considered as a natural pulse disturbance, due to its suddenness and high intensity, potentially affecting nearby species and ecosystems. Here, we present the response of Posidonia oceanica, a long-lived seagrass, to an exceptional submarine volcanic explosion, which occurred in the Aeolian Archipelago (Italy, Mediterranean Sea) in 2002, and evaluate its resilience in terms of time required to recover after such a pulse event. The study was carried out in 2011 i…
Abundance and δ13C values of fatty acids in lacustrine surface sediments: Relationships with in-lake methane concentrations
2018
Proxy-indicators in lake sediments provide the only approach by which the dynamics of in-lake methane cycling can be examined on multi-decadal to centennial time scales. This information is necessary to constrain how lacustrine methane production, oxidation and emissions are expected to respond to global change drivers. Several of the available proxies for reconstructing methane cycle changes of lakes rely on interpreting past changes in the abundance or relevance of methane oxidizing bacteria (MOB), either directly (e.g. via analysis of bacterial lipids) or indirectly (e.g. via reconstructions of the past relevance of MOB in invertebrate diet). However, only limited information is availabl…
Microwear and isotopic analyses on cave bear remains from Toll Cave reveal both short-term and long-term dietary habits
2019
Dietary habits of the extinct Ursus spelaeus have always been a controversial topic in paleontological studies. In this work, we investigate carbon and nitrogen values in the bone collagen and dental microwear of U. spelaeus specimens recovered in Level 4 from Toll Cave (Moia, Catalonia, NE Iberian Peninsula). These remains have been dated to > 49,000 C-14 BP. The ability of both proxies to provide data on the diet of U. spelaeus at different times in the life-history (isotopes: average diet of life; microwear: last days/weeks before death), allows us to generate high-resolution and complementary data. Our results show lower values (delta C-13 & delta N-15) in cave bears than in strict herb…
Cribra orbitalia as a potential indicator of childhood stress: Evidence from paleopathology, stable C, N, and O isotopes, and trace element concentra…
2016
Cribra orbitalia (CO), or porotic hyperostosis (PH) of the orbital roof, is one of the most common pathological conditions found in archaeological subadult skeletal remains. Reaching frequencies higher than 50% in many prehistoric samples, CO has been generally attributed to a variety of factors including malnutrition (e.g., megaloblastic anemia) and parasitism. In this study, we tested the relationship between CO, trace element concentrations, and stable isotope values (δ13C, δ15N, δ18O) in subadult skeletons from a 17th to 18th century cemetery in the historic town of Jēkabpils, Latvia. A total of 28 subadults were examined, seven of which (25%) showed evidence of CO. Bioarchaeological ev…
Parasite infection alters host stable-isotope composition under controlled feeding
2016
1) Stable isotopes are widely used for studying trophic relationships, but variation driven by environmental conditions or food availability complicates the interpretation of trophic dynamics. Parasites are ubiquitous and known to affect physiological functions of their hosts, but only few studies have assessed the effects of parasites on isotope composition of hosts. 2) We measured the changes in two of the most commonly used stable isotopes in food-web studies, nitrogen (i.e. 15N:14N ratio; denoted as δ15N) and carbon (13C:12C; δ13C) in Daphnia hosts exposed to infection by a parasitic micosporidian in the laboratory. Isotopic signatures of hosts fed a standardised controlled diet were co…