Climate and land-use as the main drivers of recent environmental change in a mid-altitude mountain lake, Romanian Carpathians

Haliuc, A; Buczkó, K; Hutchinson, SM; Ács, É; Magyari, EK; Korponai, J; Begy, R-C; Vasilache, D; Zak, M; Veres, D

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.

Citation

Haliuc, A., Buczkó, K., Hutchinson, S., Ács, É., Magyari, E., Korponai, J., …Veres, D. (2020). Climate and land-use as the main drivers of recent environmental change in a mid-altitude mountain lake, Romanian Carpathians. PLoS ONE, 15(10), e0239209. https://doi.org/10.1371/journal.pone.0239209

• Journal Article Type: Article
• Acceptance Date: Sep 2, 2020
• Online Publication Date: Oct 1, 2020
• Publication Date: Oct 1, 2020
• Deposit Date: Oct 2, 2020
• Publicly Available Date: Oct 2, 2020
• Journal: PLoS ONE
• Publisher: Public Library of Science
• Volume: 15
• Issue: 10
• Pages: e0239209
• DOI: https://doi.org/10.1371/journal.pone.0239209
• Keywords: Research Article, Biology and life sciences, Earth sciences, Ecology and environmental sciences, Physical sciences
• Publisher URL: https://doi.org/10.1371/journal.pone.0239209
• Related Public URLs: http://www.plosone.org/
• Additional Information: Additional Information : ** From PLOS via Jisc Publications Router ** Licence for this article: http://creativecommons.org/licenses/by/4.0/ **Journal IDs: eissn 1932-6203 **Article IDs: publisher-id: pone-d-20-09807 **History: published_online 01-10-2020; accepted 02-09-2020; submitted 06-04-2020; collection 2020; Funders : Romanian Government;EEA Grants 2014-2021;European Union and the State of Hungary;National Research, Development and Innovation Office (NKFIH); Projects : Studii privind efectele schimbărilor de utilizare a terenurilor asupra eroziunii solului și a ratelor ridicate de sedimentare folosind radionuclizi;Millennial-scale geochemical records of anthropogenic impact and natural climate change in the Romanian Carpathians;GROUNDWATERiSK;Sustainable use of ecosystem services - research for mitigating the negative effect of climate change, land use change and biological invasion;CRYPTIC project;ICUB fellowships for young researcher; Grant Number: PN-III-P1-1.1-TE-2016-0814; Grant Number: PN-IIID-PCE-2012-4-0530; Grant Number: 4/2019; Grant Number: GINOP-2.3.2.-15-2016-00019; Grant Number: OTKA 119208; Grant Number: 28539/04.12.2017