Evolution of pastoralism in Southern Greenland during the last two millennia reconstructed from bile acids and coprophilous fungal spores in lacustrine sediments

Abstract

International audienceTo reconstruct the evolution of livestock in SW Greenland over the last two millennia, we measured the concentration of bile acids in a sedimentary sequence retrieved from Lake Igaliku. Deoxycholic acid (DOC) was the sole bile acid. and was present throughout the sequence.The DOC flux correlated quantitatively with that of coprophilous fungal spores. Maximum DOC and coprophilous fungal spores fluxe was recorded during the two periods of human settlement and grazing activity in the region (i.e. the Norse settlement during the Middle Ages and the recent Danish agricultural phase since 1920). These flux values were consistent with the presence of recent livestock around the lake and are attested to by way of archaeological data relating to the Norse period. In contrast, the DOC and coprophilous fungal spores background during pre-Norse times and the Little Ice Age (LIA), indicated the presence of wild herbivores. Lower DOC and coprophilous fungal spore fluxes values after the Norse abandonment, compared with pre-colonization conditions, could indicate that Norse activity in conjunction with climate pejoration, altered durably the pristine wildlife.Therefore, these quantitative correlations between DOC and coprophilous fungal spores fluxes potentially suggest a quantitative relationship with the livestock grazing in the catchment. The comparison between sedimentary DOC and coprophilous fungal spores provides tremendous highlights on past pastoral dynamics over the last 2000 yr in SW Greenland

Long‐term dynamics in microbial eukaryotes communities: a palaeolimnological view based on sedimentary DNA

“…; Guillemot et al . ) and (ii) the recent occupation, since the 1920s, marked by moderate eutrophication around the 1980s (Austrheim et al . ; Perren et al .…”

“…This lake has been preserved from the marked eutrophication. In Greenland, only two periods of agropastoral activities were inventoried: (i) the Norse settlement period between AD 986 and the middle of the 15th century (Arneborg et al 2011;Massa et al 2012;Guillemot et al 2015) and (ii) the recent occupation, since the 1920s, marked by moderate eutrophication around the 1980s (Austrheim et al 2008;Perren et al 2012;Millet et al 2014).…”

“…), whereas the other one (Lake Igaliku) is located in Greenland and only faced episodic human forcing (local agriculture activities; Guillemot et al . ). The considered temporal framework allows to cover the main climatic periods of the last two millennia: Medieval Warm Period (MWP), Little Ice Age (LIA) and Current Warm Period (CWP) (Mckay & Kaufman ).…”

“…In this study, we investigate the temporal dynamics of microbial eukaryotes communities of two lakes based on the high-throughput sequencing (HTS) of Sed-DNA. These two lakes present contrasted settings; one located in continental Europe (Lake Bourget) is submitted to intensive land use and catchment area urbanization Millet et al 2010), whereas the other one (Lake Igaliku) is located in Greenland and only faced episodic human forcing (local agriculture activities; Guillemot et al 2015). The considered temporal framework allows to cover the main climatic periods of the last two millennia: Medieval Warm Period (MWP), Little Ice Age (LIA) and Current Warm Period (CWP) (Mckay & Kaufman 2014).…”

Fecal biomarker imprints as indicators of past human land uses: Source distinction and preservation potential in archaeological and natural archives

“…Fecal biomarkers (C27, C28 and C295β-stanols and bile acids), produced in the digestive tracts of certain large mammals (Elhmmali et al, 2000;Bull et al, 2002;Tyagi et al, 2008) are commonly used to trace human or animal fecal inputs in current environments (Nes and Nes, 1980;Elhmmali et al, 1997;Evershed et al, 1997;Bull et al, 1998Bull et al, , 1999bBull et al, , 2001Bull et al, , 2002Jardé et al, 2007a;Lavrieux et al, 2012;D'Anjouet al, 2012;Guillemot et al, 2015Guillemot et al, , 2016. However, to date, only a few studies have precisely distinguished human and animal sources in archaeological settlements (Bull et al, 2003) or in the surrounding area (Shillito et al, 2011a).…”