Hydroclimatic variability is expected to be affected by global warming in the Mediterranean region where climate, fire and human activities are known to be interdependent. The latter is examined here for the past millennium by studying paleoenvironmental indicators from a sedimentary sequence at Lagunillo del Tejo (Cuenca, central Spain). Inferred changes in fire activity and lake levels are based on records of macrocharcoals and plant/algal macrofossils, respectively, and are compared with independent information on climate change and socio-economical transformations from historical and meteorological records. The results show that there is an obvious climatic forcing behind the lake-level changes recorded at Lagunillo del Tejo, and a good correlation between the periods of high fire activity/frequent fires and low lake level/drought conditions. The reconstructed fire regime may therefore be natural (climate-induced), but can also be explained by important socio-economical events/changes, including wars and the introduction of the Transhumance practices (ad 1273). There is a good chronological agreement between lowest fire activity and high lake levels ( c. ad 1600–1800), concurrent with the late ‘Little Ice Age’ (LIA) and the collapse of the Transhumance system. We propose that periods of drought favored both natural and human-induced fires during the ‘Medieval Climatic Anomaly’ (around ad 1200), at the start of the LIA (around ad 1400), in the middle of the LIA (sixteenth century) and during the entire nineteenth century. This record is an example of long-term interplay between climate changes and human activities and its impact on environmental changes such as fire regimes.

The anthropogenic impact on wetlands has increased during the last centuries when infrastructures such as canals or dams, have proliferated. In this article, we have used cladoceran sub-fossils to investigate the effects of a canal on lake El Tobar (Spain). The canal has been transferring water from a reservoir, built in another valley, into this lake since its construction in the mid1960s. Cladoceran remains were analyzed in two sediment profiles from each of the two sub-basins of the lake. The sedimentary sequences showed that the mentioned human activity provoked a clear shift in the cladoceran community. A PCA was performed with samples from both sub-basins to detect the direction and nature of the changes. Before water transference, the phytophilous chydorid community, represented by Acroperus angustatus in one sub-basin and by both A. angustatus and Graptoleberis testudinaria in the other sub-basin, were well developed. After the construction of the canal and the inflow of additional yet different water from the reservoir, the proportion of chydorids relative to total cladoceran diminished considerably; this was mainly due to the invasion of Bosmina longirostris. These results indicate that the hydrological alteration caused a shift from an oligotrophic, shallower lake with a rich plant-associated cladoceran community to a more eutrophic lake with a predominant planktonic cladoceran community; and that cladoceran remains are a powerful tool to detect hydrological changes and eutrophication.

Gold mining is known to generate important economic products but also to produce several types of contamination/pollution. We report here the first data about Hg concentrations in the soils of the Yacuambi River in the Ecuadorian Amazon. We analyzed soil samples to assess the extent of contamination caused by gold placer mining in this area. Hg concentrations in soils exceeded the local background concentrations. High concentrations of Mn, As, Pb, Cr, Cu, Fe and Zn in some soil samples were probably derived from the geology of the site, which is rich in polysulfides and metamorphic rocks. Placer mining may accelerate the natural release of these elements to the environment by the exposure of the bedrock to the atmosphere. Accumulation of Hg in the river soils may be a potential source of toxicity for aquatic life and a risk to human health in the future.

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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.