Hypersaline lakes are unique depositional environments that are highly sensitive to climatic changes and anthropogenic pressures. Strong physicochemical gradients and the interplay of physical, chemical and biological depositional processes coupled to variable preservation potential associated with these environments generate highly complex sedimentary sequences. This study aimed to investigate spatio‐temporal variations throughout the last three centuries in the sedimentary sequence of Laguna Salada de Chiprana, a small, permanent hypersaline lake situated in Northeast Spain. Short sediment cores reveal a complex sedimentary sequence influenced by detrital, chemically‐induced and biogenically‐influenced depositional processes. Nine facies associated with six sedimentological units represent six periods of environmental change beginning from approximately pre‐1800 ad to the present day. They include: (i) a shallow, permanent saline lake that experienced brief periods of anoxia and drawdown between pre‐1800 ad and ca 1850 ad. This was succeeded by: (ii) increased lake levels and detrital input to the lake from ca 1850 to 1900 ad; and (iii) a fall in lake levels and the establishment of microbial mats within bottom waters fluctuating between oxic and anoxic conditions from ca 1900 to 1950 ad. (iv) From ca 1950/1960 ad, a minor increase in lake levels and colonization of the littoral and sub‐littoral zones by macrophytic vegetation occurred; followed by (v) falling lake levels and increasing salinity between 1960 and 1970 ad leading to widespread encrustation of macrophytes in the littoral zones by carbonate–evaporite precipitates. Finally (vi), from ca 1970 ad to the present day, falling lake levels, elevated salinity and widespread colonization of the lake by microbial mats characterize the sedimentary environment. Climate reconstructions and documentary evidence indicate that depositional evolution was mostly controlled by changes in farming practices and irrigation policies. Understanding Laguna Salada de Chiprana’s depositional evolution contributes to future definitions of high‐resolution palaeoenvironmental models, not only within the Iberian Peninsula but also in other locations where saline–hypersaline lakes act as a key source of palaeoenvironmental information.

<p>High altitude mountain lakes archive high-resolution records of environmental variability (climatic and anthropic). The REPLIM project funded by the INTERREG program (POCTEFA 2014-2020) has implemented a network to understand current and past changes in Pyrenean lakes. In this work, we compare six high altitude lake records along a W- E transect in the South Central Pyrenees: Acherito (1877 m.a.s.l.), La Sierra (2022 m.a.s.l.), Sabocos (1900 m.a.s.l.), Marboré (2600 m.a.s.l), Urdiceto (2364 m.a.s.l.) and Cregueña (2633 m.a.s.l.).</p><p>In each lake we have analyzed short sediment cores across transects applying sedimentological (facies, grain size, sediment composition, thin sections), geochemical (XRF scanner, elemental and trace metals) physical (Magnetic Susceptibility), isotopic (δ<sup>13</sup>C and δ <sup>15</sup>N of bulk organic matter) and biological (diatoms) techniques. The age models have been constructed with <sup>137</sup>Cs, <sup>210</sup>Pb and <sup>14</sup>C dates.</p><p>The sedimentary dynamics and heavy metals depositional history for the last 2000 years provides a temporal context for recent changes. Sedimentary facies variability correlates with climate phases and reflect varied human pressures. In general, during the colder and more humid periods, usually associated with glacier advances (LIA and Late Antiquity LIA), higher surface runoff was generated and, therefore, sediment delivery to the lake increased, in some cases with deposition of coarser facies. Intense watershed disturbances due to human impact were noticeable in lower altitude lakes since early medieval times. All lakes show larger sediment rate variability during the last centuries, but the timing of the onset varies. Lakes located at higher altitudes (Marboré and Cregüeña) show larger changes in sedimentation rates and dynamics around the end of the LIA (ca. 1850 CE), while in lower altitude lakes (Sierra, Sabocos, Acherito) occurred later (ca. 1950 CE).  In most lakes, a significant increase in organic matter accumulation started at the end of the 19th century and the trend accelerated since mid 20th century. Diatom and isotopes analyses suggest an increase in lake primary productivity during the last decades. The results indicate that the combined impacts of climate change and increased human pressure in the Pyrenees at the end of the LIA had a greater impact on high-altitude lakes, but recent changes in the 20th century have affected the lakes at all altitudes</p><p>All lakes show a similar heavy metal deposition pattern, with enrichment during Roman and Medieval times and a progressive increase since the end of the 18<sup>th</sup> century (industrialization) and reaching its peak in the middle and late 20<sup>th</sup> century. Some metals, such as Pb, show a subsequent decline at the end of the 20<sup>th</sup> century related to the reduction of industrial emissions and the ban on leaded gasoline.</p><p>This integrated approach demonstrates the sensitivity of high altitude lake systems to record past changes and highlights the need for multi-archive studies to support regional reconstructions of past environmental and climate changes.</p>