Late Pleistocene–Holocene environmental conditions in Lanzarote (Canary Islands) inferred from calcitic and aragonitic land snail shells and bird bones

• Published in: Palaeogeography, palaeoclimatology, palaeoecology Vol. 378; pp. 91 - 102
• Main Authors: Yanes, Yurena, García-Alix, Antonio, Asta, María P., Ibáñez, Miguel, Alonso, María R., Delgado, Antonio
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-05-2013
• Subjects: Extinctions; Land snails; Lanzarote; Quaternary; Seabirds; Stable isotopes; Seabirds; Land snails; Extinctions; Lanzarote; Quaternary; Stable isotopes
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2013.03.020

Aragonitic and calcitic land snails from carbonate-rich paleosols in northwestern Lanzarote (Canary Islands) were analyzed for 13C/12C and 18O/16O ratios to deduce the Pleistocene–Holocene transition in the westernmost Sahara zone. Modern, mid-late Holocene (~2.1–5.5calka BP) and late Pleistocene (~23.3–24.0calka BP) aragonitic shells exhibited respective values of −9.5±1.6‰, −7.7±1.5‰, and −2.3±2.8‰ for δ13C; and +0.3±0.3‰, +0.1±0.7‰, and +2.5±0.4‰ for δ18O. Holocene and Pleistocene calcitic shells of the endemic slug Cryptella canariensis showed respective values of −0.7±2.6‰ and −8.5±2.5‰ for δ13C; and +0.8±1.5 and +3.6±0.4‰ for δ18O. Both aragonitic and calcitic shells showed equivalent temporal isotopic trends. Higher δ13C values during ~23.3–24.0calka BP suggest higher abundance of C4 and/or CAM plants, likely associated with drier conditions and/or lower atmospheric CO2 concentration. Maximum shell δ18O values during ~23.3–24.0calka BP opposes minimal values of Greenland ice cores and probably reflect the combined effects of (1) higher rain δ18O values linked to higher glacial seawater δ18O values and/or larger snail activity during summer seasons; (2) relative humidity values similar or slightly lower than at present; (3) higher evaporation rates; and (4) cooler temperatures. Bone remains of the extinct Dune Shearwater Puffinus holeae were only recovered from the Holocene bed. Collagen δ13C and δ15N values (−13.5±0.2‰[PDB] and +13.7±1.0‰[air], respectively) match with the signature of a low trophic level Macaronesian seabird that fed upon local fish. Bone carbonate δ13C (−7.4±1.0‰[PDB]) and phosphate δ18O (+18.2±0.4‰[SMOW]) values exhibited pristine signals denoting their potential value in future paleoenvironmental studies in the region. The age of P. holeae (~2.1–2.7calka BP) supports that the aboriginal population possibly caused its extinction. In contrast, the extinction of the endemic helicid Theba sp. (~23.3–24.0calka BP) was likely caused by environmental change.
•Calcitic and aragonitic land snail shells record similar information in the Canaries.•Rain δ18O was higher at ~23–24ka and RH was similar or lower than at present.•C4 and/or CAM plants were more abundant in the Canaries during ~23–24ka than today.•Snails tracked comparable environmental conditions during ~2–5ka and the present.•Bones of extinct and extant seabirds are valuable for paleoenvironmental studies.