Sedimentary multiproxy response to hydroclimatic variability in Lagunillo del Tejo (Spain)

Abstract

Lagunillo del Tejo is a small groundwater-fed sinkhole lake in the karst region of the Iberian Range (central-eastern Spain), which undergoes significant lake level fluctuation in response to rainfall variability. The aim of this study is to understand the record of water level fluctuations in Lagunillo del Tejo over the last two-and-a-half centuries. This information could be used in future studies to interpret longer sedimentary sequences. We analysed photosynthetic pigments, diatoms and cladoceran remains in sediment sequences recovered from the deepest part of the lake. The paleoecological proxies traced two different communities which have switched their prevalence during the past: (1) a planktonic community of algae, including diatoms, chlorophytes, cryptophytes and cyanobacteria, and phototrophic bacteria associated with higher lake level and water column seasonal stratification; (2) a littoral community with the higher levels of macrophyte pigments and associated epiphytic diatoms and chydorids, all of which indicate lower lake level. The levels of coherence between different proxies, each having an independent mechanistic link to lake-level variability, enhance the reliability of palaeolimnological inferences. The high-resolution stratigraphical data from the upper part of the core was compared with lake-level inferences from instrumental rainfall series to establish the correspondence between Lagunillo del Tejo sediment sequences and climate record.

Erosion in Mediterranean mountain landscapes during the last millennium: a quantitative approach based on lake sediment sequences (Iberian Range, Spain)

“…Lake sediments have been shown to be exceptional archives of past environmental (Ambers, 2001;Bennett and Buck, 2016;Birck et al, 2013;Détriché et al, 2013;Sadori et al, 2016), climatic (Magny and Combourieu, 2013;Roberts et al, 2012), erosion (Anselmetti et al, 2007;Giguet-Covex et al, 2011;Van der post et al, 1997) and human landscape evolution (Dearing et al, 1987;De Boer, 1994;Enters et al, 2008) at regional scale (Lionello, 2012). Detail records for the last millennium are available from several karstic lakes in the Iberian Range: La Cruz (Burjachs, 1996;Julià et al, 1998;Romero-Viana et al, 2008, Lagunillo del Tejo (López-Blanco et al, 2011;Romero-Viana et al, 2009), El Tejo and La Parra (Barreiro-Lostres et al, 2013 located in the Cañada del Hoyo lakes-sinkhole system in the Serranía Media de Cuenca; and from Taravilla Lake Valero-Garcés et al, 2008) and from El Tobar Lake (Barreiro-Lostres et al, 2015) both located in the Serranía Alta de Cuenca. These lakes act as sediment traps for their watersheds and the intense depositional processes lead to high sedimentation rates and thick deposits, providing long continuous sedimentary sequences with a high temporal resolution and an exceptional sensitivity to both regional hydrological balances and human induced land-use (Valero-Garcés et al, 2014).…”

Climate, palaeohydrology and land use change in the Central Iberian Range over the last 1.6 kyr: The La Parra Lake record

“…Lake records spanning the last millennium are available from three lakes of the Cañada del Hoyo karstic system (Figure 1): La Cruz (Burjachs, 1996; Julià et al, 1998; Rodrigo et al, 2001; Romero-Viana et al, 2008, 2009a, 2011), Lagunillo del Tejo (López-Blanco et al, 2011; Romero-Viana et al, 2009b) and La Parra (this study). Although chronological models do not have similar resolution (Figure 1), and the proxies used to reconstruct lake level and environmental changes differ from one another, the proximity of these lakes provide an opportunity to evaluate the regional significance of reconstructed hydrological/environmental changes in a context of similar climate forcing and human impact.…”

“…However, watershed topography, bathymetry and land uses seem to play a definitive role in each lake basin. In Lagunillo del Tejo, lake levels dropped and erosion increased because of the construction of agricultural terraces within the lake basin (López-Blanco et al, 2011; Romero-Viana et al, 2009b). Lake La Cruz maintained a high water level with varves sedimentation until present day (Julià et al, 1998).…”

Evolución sedimentaria del lago kárstico de La Parra (Cuenca) durante los últimos 1600 años: paleohidrología, clima e impacto humano

“…Aunque la sedimentación de limos más finos sugiere una recuperación de los niveles hidrológicos durante el siglo XIX, los elevados valores de la relación TOC/TN testifican el elevado impacto humano en la cuenca hasta mediados del siglo XX. En el Lagunillo del Tejo se observa también un aumento en la tasa de sedimentación durante el siglo XIX y comienzo del XX, coincidiendo en este caso con niveles del lago más bajos (Romero-Viana et al, 2009;López-Blanco et al, 2011).…”