Abrupt diatom responses to recent climate and land use changes in the Cantabrian Mountains (NW Spain)

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Gardoki, Jon and Morellón Marteles, Mario and Leira, Manel and Ezquerra, F. Javier and Remondo, Juan and Tinner, Willy and Canales Fernández, María Luisa and van der Horst, Anouk and Morales Molino, César (2022) Abrupt diatom responses to recent climate and land use changes in the Cantabrian Mountains (NW Spain). Journal of paleolimnology . ISSN 0921-2728

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Official URL: https://doi.org/10.1007/s10933-022-00269-2



Abstract

The multi-proxy study of sediment cores from Lake Isoba (43° 02′ N, 5° 18′ W; 1400 m a.s.l.) allows a detailed assessment of the past hydrological and environmental dynamics in north-western Iberia resulting from the interplay between climate variability and anthropogenic impact. The combination of diatom stratigraphy, sedimentology and high-resolution elemental geochemistry along with a robust chronological framework (established by 210Pb, 137Cs and 14C dating) provides a detailed environmental reconstruction for the past ~ 500 years. Abrupt changes in the fossil diatom assemblages indicate a high sensitivity of this small lake to past environmental change and allow identifying four major stages related to the main climate fluctuations of the Little Ice Age (LIA) and recent warming. High lake levels, enhanced runoff and higher productivity characterised the middle phase of the LIA (~ 1550 to 1630 CE), indicating an overall wet climate. Conversely, shallow lake levels, decreased runoff and relatively low productivity prevailed during the last phase of the LIA and the onset of the Industrial Era (~ 1630 to 1925 CE), likely due to colder and drier conditions. High lake levels and higher carbonate input occurred after ~ 1925 CE until the 1980s CE, when our data show an abrupt drop in lake levels probably caused by a regional negative rainfall anomaly related to climate warming during the past decades. Finally, since ~ 1997 CE a remarkable and abrupt increase in the lake nutrient load and turbidity is detected, probably associated with the replacement of transhumant sheep flocks with staying cattle. The main environmental changes reconstructed at Lake Isoba mostly agree with other palaeoclimatic records from northern Spain. However, the hydrological patterns reconstructed are opposed to those observed on the northern slopes of the Cantabrian Mountains. The recent and strong impact of land-use changes on the lake, causing more ecological disruptions than previous climate changes, is noteworthy and demonstrates the high sensitivity of mountain lakes to human activities in a global change context.


Item Type:Article
Uncontrolled Keywords:Lake sediments, Late Holocene, Climate change, Transhumance, Eutrophication
Subjects:Sciences > Geology > Stratigraphic geology
ID Code:75232
Deposited On:21 Oct 2022 16:30
Last Modified:07 Nov 2022 08:38

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