Loïc Harrault

Université de Bretagne Occidentale | UBO · Institut Universitaire Européen de la Mer (IUEM)

Recent investigations of an apparently ‘empty,’ partly disturbed Viking chamber grave in Denmark (Fregerslev II, dated around the mid-10th century CE) provided an opportunity to develop a novel multi-scale and multi-method analysis of burial and post-burial processes. To overcome the limitations of poor preservation of artefacts and bones, and the...

Herbivory plays a significant role in regulating many contemporary terrestrial plant ecosystems, but remains an imperfectly understood component of past ecosystem dynamics because the diagnostic capability of methods is still being tested and refined. To understand the efficacy of a multiproxy approach, we compare the sensitivity of pollen and copr...

Arctic reindeer herders demonstrate resilience to climate fluctuations by adjusting their pastoral practices to changing environments. The multiple phases of occupation at one of the oldest identified reindeer-herding sites, I͡Arte 6 on the I͡Amal peninsula, northwest Siberia, are thought to be linked to its local vegetation cover. Here we provide...

Identifying the presence of animals based on faecal deposits in modern and ancient environments is of primary importance to archaeologists, ecologists, forensic scientists, and watershed managers, but it has proven difficult to distinguish faecal material to the species level. Until now, four 5β-stanols have been deployed as faecal biomarkers to di...

Example GC-MS chromatogram (total ion current) from a reindeer sample (R12, see S2 Table). Retention times correspond to the analytical method used for this sample as described in Materials and Methods and S2 Table. Trivial names of the eleven 5β-stanols considered in this study are labelled black (S1 Table). Trivial names of 5α-stanols and sterol...

Mass spectra and summarised fragmentation patterns of TMSi ether derivatives of eleven 5β-stanols found in faecal samples. M+ = molecular fragment. SC = side chain. TMSiOH = trimethylsilanol fragment. Me = methyl. Identification of 5β-lichestanol was made by comparison with the mass spectra of the TMSi ether derivative of stellasterol (24-methyl-5α...

Comparison of diet and species identification between ratios and multivariate analyses for both case study sites. (XLSX)

5β-stanol names and GC-MS properties. 5β-stanols considered in this study and common 5α-stanols and sterols found in samples analyzed. Chromatographic and mass-spectrometric properties for identification and quantification of listed compounds are also presented. (XLSX)

Characteristics of the first four principal components, variables and species distinction of the PCA built on the distribution of 5β-stanols in all ten species faeces. Characteristics of the HCPC model built on the PCA. Variables and species loadings on PCs 1, 2, 3 and 4 show which variables contribute the most (absolute value) to distinguish betwe...

Characteristics of the first four principal components, variables and species distinction of the PCA built on the distribution of 5β-stanols in human, dog, horse and reindeer faeces (selected for the Tofa site context, Sai͡an Mountains). Characteristics of the HCPC model built on the PCA. Variables and species loadings on PCs 1, 2, 3 and 4 show whi...

Characteristics of the first four principal components, variables and species distinction of the PCA built on the distribution of the four main 5β-stanols (coprostanol, epicoprostanol, 24-ethylcoprostanol and 24-ethylepicoprostanol) in human, dog, horse and reindeer faeces (selected for the Tofa site context, Sai͡an Mountains). Characteristics of t...

Sample information and 5β-stanol distribution. Information relative to sample collection and analytical method as presented in Materials and Methods, 5β-stanol distribution and sum, concentration of main 5α-stanols and recovery efficiency of internal standard when added. (XLSX)

AMS dating information for the buried soils at the I͡Arte 6 site, I͡Amal peninsula. Red text indicates outliers. The radiocarbon calibration multiplot provides a graphical summary of the data in the S2 Table. The results show that the buried soils adjacent to I͡Arte 6, which contained faecal lipids, developed between the 6th and early 11th century...

Characteristics of the first four principal components, variables and species distinction of the PCA built on the distribution of 5β-stanols in human, dog, horse and reindeer faeces (selected for the I͡Amal site context). Characteristics of the HCPC model built on the PCA.Variables and species loadings on PCs 1, 2, 3 and 4 show which variables cont...

Characteristics of the first four principal components, variables and species distinction of the PCA built on the distribution of the four main 5β-stanols (coprostanol, epicoprostanol, 24-ethylcoprostanol and 24-ethylepicoprostanol) 5β-stanols in human, dog, horse and reindeer faeces (selected for the I͡Amal site context). Characteristics of the HC...

This study identified sources of fecal contamination in three different French headwater and coastal catchments (the Justiçou, Pen an Traon, and La Fresnaye) using a combination of microbial source tracking tools. The tools included bacterial markers (three host-associated Bacteroidales) and chemical markers (six fecal stanols), which were monitore...

Contamination of coastal and shellfish harvesting areas from human and animal waste poses sanitary risks and leads to economic losses. Mussels, oysters (mainly Crassostrea gigas), and similar suspension filter-feeders are particularly sensitive to microbial pathogens, because they accumulate environmental contaminants in their tissues.

In this study, the capacity of oysters to bioaccumulate fecal stanols and to record a source-specific fingerprint was investigated by the short-term contamination of seawater microcosms containing oysters with a human effluent. Contaminated oysters bioaccumulated the typical fecal stanols coprostanol and 24-ethylcoprostanol and their bioaccumulatio...

The objective of this work was to study the effects of washing and purification steps on qualitative and quantitative analysis of fecal stanols in the oyster Crassostrea gigas using either single or a combination of lipid purification steps on silica gel or aminopropyl bonded silica gel (NH2) or a washing step. Among the three analytical pathways c...

Sediment plays a key role in organic matter (OM) and internal nutrient cycling in lakes. The role of sediment as a source of OM and its potential bottom-up effects on the pelagic food web have rarely been studied. Particularly, the influence of the biochemical composition of sediment OM on pelagic compartments remains largely unknown. During a 5-mo...

Soil erosion in freshwaters induces important changes in lake metabolism. The organic matter and the nutrients supplied by soil inputs can change internal biogeochemical cycles and subsidize the whole food web from basal organisms to top-predators. Since the last two decades, the role of allochthonous organic matter as a basal resource for aquatic...

Runoff of cattle manures (cows, pigs, sheeps) or discharge of effluent from wastewater treatment plants (WWTP) into aquatic ecosystems can lead to microbiological contamination of waters and living organisms. In coastal ecosystems and particularly in shellfish harvesting areas, the presence of pathogen microorganisms in waters induces fecal contami...

In the context of global change, eroded soil carbon fate and its impact on aquatic ecosystems CO2 emissions are subject to intense debates. In particular, soil carbon mineralization could be enhanced by its interaction with autochthonous carbon, a process called priming effect, but experimental evidences of this process are scarce. We measured in a...

1. Sediment plays a key role in internal nutrient cycling and eutrophication in lakes. However, studies focusing on the efficiency of the biomanipulation techniques for improving the control of primary producers have rarely examined the effects of changes in food-web structure on the sediment biochemical composition and biodegradability. 2. In a 1-...

Within lakes, carbon and nutrient cycles are partly controlled by sedimentation, allochthonous inputs, food-web structure and interactions between these compartments and/or processes. As sources of organic matter and nutrients for aquatic ecosystems, sediments and terrestrial materials can exert a bottom-up forcing on pelagic communities. Top-preda...