Climate and land-use as the main drivers of recent environmental change in a mid-altitude mountain lake, Romanian Carpathians
Open Access
- 1 October 2020
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 15 (10), e0239209
- https://doi.org/10.1371/journal.pone.0239209
Abstract
Recent decades have been marked by unprecendented environmental changes which threaten the integrity of freshwater systems and their ecological value. Although most of these changes can be attributed to human activities, disentagling natural and anthropogenic drivers remains a challenge. In this study, surface sediments from Lake Ighiel, a mid-altitude site in the Carpathian Mts (Romania) were investigated following high-resolution sedimentological, geochemical, environmental magnetic and diatom analyses supported by historical cartographic and documentary evidence. Our results suggest that between 1920 and 1960 the study area experienced no significant anthropogenic impact. An excellent correspondence is observed between lake proxy responses (e.g., growth of submerged macrophytes, high detrital input, shifts in diatom assemblages) and parameters tracking natural hydroclimate variability (e.g., temperature, NAO). This highlights a dominant natural hydroclimatic control on the lacustrine system. From 1960 however, the depositional regime shifted markedly from laminated to homogenous clays; since then geochemical and magnetic data document a trend of significant (and on-going) subsurface erosion across the catchment. This is paralleled by a shift in lake ecosystem conditions denoting a strong response to an intensified anthropogenic impact, mainly through forestry. An increase in detrital input and marked changes in the diatom community are observed over the last three decades, alongside accelerated sedimentation rates following enhanced grazing and deforestation in the catchment. Recent shifts in diatom assemblages may also reflect forcing from atmospheric nitrogen (N) deposition, a key recent drive of diatom community turnover in mountain lakes. In general, enhanced human pressure alongside intermittent hydroclimate forcing drastically altered the landscape around Lake Ighiel and thus, the sedimentation regime and the ecosystem’s health. However, paleoenvironmental signals tracking natural hydroclimate variability are also clearly discernible in the proxy data. Our work illustrates the complex link between the drivers of catchment-scale impacts on one hand, and lake proxy responses on the other, highlighting the importance of an integrated historical and palaeolimnological approach to better assess lake system changes.This publication has 83 references indexed in Scilit:
- The AnthropoceneAnnual Review of Earth and Planetary Sciences, 2013
- Early Anthropogenic Transformation of the Danube-Black Sea SystemScientific Reports, 2012
- Nutrients exert a stronger control than climate on recent diatom communities in Esthwaite Water: evidence from monitoring and palaeolimnological recordsFreshwater Biology, 2011
- Identifying from recent sediment records the effects of nutrients and climate on diatom dynamics in Loch LevenFreshwater Biology, 2011
- Quantifying Recent Ecological Changes in Remote Lakes of North America and Greenland Using Sediment Diatom AssemblagesPLOS ONE, 2010
- ITRAX: description and evaluation of a new multi-function X-ray core scannerGeological Society, London, Special Publications, 2006
- The Atlantic Multidecadal Oscillation and its relation to rainfall and river flows in the continental U.S.Geophysical Research Letters, 2001
- Biodiversity changes in a shallow lake ecosystem: a multi‐proxy palaeolimnological analysisJournal of Biogeography, 1999
- Diatom-based Model to Infer Past Littoral Habitat Characteristics in the St. Lawrence RiverJournal of Great Lakes Research, 1997
- The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sedimentCATENA, 1978