The discovery of spatial patterns in naturally occurring isotopes (e.g., δ2H, δ13C) at continental scales has been tremendously important in providing a method to infer potential breeding and wintering origins of migratory animals through assignment to tissue-specific isoscapes. Single-isotope (i.e. δ2H) assignments of birds to molting origins in South America have been limited by the lack of strong spatial gradients in precipitation δ2H there. We integrated an mvnpdf (multivariate normal probability density function) approach using δ2H and δ13C values in tail feathers to determine wintering origins of adult Barn Swallows (Hirundo rustica) breeding in eastern Canada (n = 208). Spatial assignments were conducted using precipitation (δ2H) and theoretical plant-based (δ13C) isoscapes for South America calibrated for feathers of Nearctic–Neotropical migrant songbirds. We also measured feather δ34S values of Barn Swallows equipped with geolocators (n = 9) and of a larger group of Barn Swallows (n = 12...

The Caribbean spiny lobster, Panulirus argus, is one of the most valuable fisheries commodities in the Central American region, directly employing 50,000 people and generating >US$450 million per year [1]. This industry is particularly important to small island states such as The Bahamas, which exports more lobster than any other country in the region [1]. Several factors contribute to this disproportionally high productivity, principally the extensive shallow-water banks covered in seagrass meadows [2], where fishermen deploy artificial shelters for the lobsters to supplement scarce reef habitat [3]. The surrounding seabed communities are dominated by lucinid bivalve mollusks that live among the seagrass root system [4, 5]. These clams host chemoautotrophic bacterial symbionts in their gills that synthesize organic matter using reduced sulfur compounds, providing nutrition to their hosts [6]. Recent studies have highlighted the important role of the lucinid clam symbiosis in maintaining the health and productivity of seagrass ecosystems [7, 8], but their biomass also represents a potentially abundant, but as yet unquantified, food source to benthic predators [9]. Here we undertake the first analysis of Caribbean spiny lobster diet using a stable isotope approach (carbon, nitrogen, and sulfur) and show that a significant portion of their food (∼20% on average) is obtained from chemosynthetic primary production in the form of lucinid clams. This nutritional pathway was previously unrecognized in the spiny lobster’s diet, and these results are the first empirical evidence that chemosynthetic primary production contributes to the productivity of commercial fisheries stocks.

Very little is known on the exposure of high trophic level species to current-use brominated (BFRs) and phosphorus flame retardants (PFRs), although observations on their persistence, bioaccumulation potential, and toxicity have been made. We investigated the accumulation of BFRs and PFRs, and their associations with dietary proxies (δ(13)C, δ(15)N and δ(34)S), in plasma and feathers of White-tailed Eagle Haliaeetus albicilla nestlings from Trøndelag, Norway. In addition to accumulation of a wide range of polybrominated diphenyl ether (PBDE) congeners in both plasma and feathers, all non-PBDE BFRs and PFRs could be measured in feathers, while in plasma only two of six PFRs, i.e. tris-(2-chloroisopropyl) phosphate (TCIPP) and tris-(2,3-dichloropropyl) phosphate (TDCPP) were detected. PFR concentrations in feathers (0.95-3,000 ng g(-1)) were much higher than selected organochlorines (OCs), such as polychlorinated biphenyl 153 (CB 153; 2.3-15 ng g(-1)) and dichlorodiphenyldichloroethylene (p,p'-DDE; 2.3-21 ng g(-1)), PBDEs (0.03-2.3 ng g(-1)) and non-PBDE BFRs (0.03-1.5 ng g(-1)). Non-significant associations of PFR concentrations in feathers with those in plasma (P ≥ 0.74), and their similarity to reported atmospheric PFR concentrations, may suggest atmospheric PFR deposition on feathers. Most OCs and PBDEs, as well as tris(chloroethyl) phosphate (TCEP), tris(phenyl) phosphate (TPHP) and tri-(2-butoxyethyl) phosphate (TBOEP) were associated to δ(15)N and/or δ(13)C (all P ≤ 0.02). Besides δ(15)N enrichment, δ(34)S was depleted in nestlings from fjords, inherently close to an urbanised centre. As such, both may have been a spatial proxy for anthropogenic disturbance, possible confounding their use as dietary proxy.

This study tracks temporal variations in the habitat use of breeding adult greater flamingos (Phoenicopterus roseus) in the Camargue (southern France) using simultaneous sampling of δ15N, δ13C and δ34S from feather and blood of chicks at fledging. Camargue flamingos forage in a heterogeneous complex of saltpans, permanent and temporary brackish lagoons, freshwater and euryhaline marshes to provision their chicks over a two month period. Using Bayesian mixing models with diet- and tissue-specific discrimination factors and invertebrates collected from 23 locations, we investigated whether blood and feather isotopes indicated temporal variations in habitat use relative to salinity and hydroperiod. We also tested whether fledgling body condition could be explained by the isotopic signatures of their tissues. While δ13C and δ15N values did not differ significantly between blood and feather, marked differences were apparent in the δ34S values obtained from these tissues. Saltpans (38%) and freshwater marshes (33%) appeared to be the main habitats visited by adult birds in the early phase of parental care with use of saline wetlands increasing later in the season (54%). This habitat shift may be related to the peak of resources in saltpans and the drying up of freshwater and brackish marshes by mid-summer. Habitat shift (as expressed in individual shifts in isotope values between feather and blood) was not correlated with offspring age, and differed between individuals. A negative relationship was observed between offspring body condition and feather δ15N, indicating that chicks fed from temporary flooded marshes fare better than those provisioned from permanent marshes. Foraging strategies of greater flamingos during parental care were heterogeneous, possibly tracking changes in resource availability as the season progressed and reflecting differences in the competitive ability of parent birds. Given that the Camargue saltpans face closure and the region's temporary wetlands remain threatened, our results emphasize the critical importance of conserving these two key habitats for greater flamingos. Dual tissue, triple-stable isotope analysis provides a useful and sensitive means of tracking localized environmental change in this threatened system. © 2013 Elsevier Ltd. All rights reserved.