the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 23 Jun 2026
A 3,000-yr lacustrine record of climate and environmental change and their influence on aquatic communities from Andean Puna lakes
Abstract. High Mountain Lakes in the Central Andean Altiplano experienced significant fluctuations in water levels during the Late Quaternary, which have affected the composition of aquatic communities. In this study, Casiri Hembra and Casiri Macho Lakes (Northern Chile, > 4,800 m a.s.l.) sediment cores were obtained and analyzed by combination of different proxies: analyses of geochemistry, magnetic properties, and pollen assemblage, joint to ecological proxies, such as the structure of benthic macroinvertebrates, to identify environmental changes that occurred in the Altiplano region during the late Holocene, with particular emphasis on distinguishing local influences from broader regional processes and their impacts on aquatic community structure and surrounding vegetation of these isolated high-mountain lakes. Results showed a progressive change in depositional dynamics from the Late Holocene to the present, 900 years in Casiri Hembra Lake, and over 3,000 years in Casiri Macho Lake. Older sediments show a general dominance of fine-grained sediments, with episodes suggesting the influence of high-energy clastic inputs, likely reflecting episodic flooding or increased basin runoff. Recent deposits indicate the development of low-energy lacustrine conditions, increased productivity, and reduced terrigenous input. Volcanic activity of the surrounding complex was recorded. The aquatic community of Casiri Lakes shows a significant replacement of taxa, from Ostracoda and Diptera in older sediments to Anostraca Crustacea in the most recent sediments. In addition, the presence of local microhabitats for the observed community is noted. High sedimentation rates in Casiri Lakes suggest complementary depositional sources to authigenic processes, such as sustained atmospheric deposition, which likely represents a significant contribution to the sediment budget.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-3159', Anonymous Referee #1, 28 Jul 2026
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RC2: 'Comment on egusphere-2026-3159', Anonymous Referee #2, 14 Oct 2026
General Assessment
The manuscript presents a multiproxy analysis based on two lacustrine sediment cores from the Chilean Altiplano-Puna, covering the last 3000 cal yr BP. Although this work has the potential to contribute meaningfully to our understanding of high Andean lake ecosystem dynamics, it requires substantial revision before it can be considered for publication.Abstract
The abstract requires revision. Although the study appears to aim at distinguishing local influences from broader regional processes affecting aquatic communities, the abstract does not address this point explicitly. Instead, it presents inferences drawn from the results without discussing their implications for understanding the local and regional drivers of change in these ecosystems. The authors should include a sentence that clearly reflects the central aim of the study.Introduction
The Introduction urgently needs attention. A well-developed introduction is essential to situating this work within the existing literature and justifying its relevance. As it stands, the section lacks sufficient bibliographic support, particularly regarding the role of benthic macroinvertebrates as a paleoecological proxy, a topic that underpins the entire study and must be more thoroughly integrated into the narrative. The authors should expand this section by incorporating additional literature on Andean-Altiplano lake systems to strengthen the study's aims and clarify why investigating these ecosystems is timely and relevant.Research Objective
The research objective requires substantial revision. As written, it is a single, overloaded sentence that mixes methodological description with ecological and geographical goals, making it hard for readers to identify the central research question. A well-formulated objective should be concise, focused, and clearly state what the study intends to achieve, independently of the methods used to achieve it.
In its current form, the objective does not provide a clear enough foundation for the rest of the manuscript. This has several consequences: the abstract does not explicitly reflect the aim of the work, the Introduction does not build a narrative that leads naturally to it, and the Conclusions do not return to it with a direct answer. A clearly stated objective is the backbone of a scientific manuscript; without it, the work's overall coherence is compromised.
The authors should reformulate the objective in precise terms, link it to the broader scientific context established in the Introduction, and ensure it is consistently reflected throughout the manuscript, from the abstract to the final conclusions.Methods
The Methods section includes an overly detailed description of the study site's geology and sediment core chronology. While some contextual information is necessary to characterise the study area, the level of detail exceeds what is needed, given how the manuscript subsequently uses it. Specifically, the Results and Discussion sections do not revisit much of this geological and chronological detail, raising questions about its relevance to the study's central aims.
As a general principle, the depth of description in the Methods should be proportional to the role that information plays in supporting the interpretation of the results. The authors are encouraged to critically evaluate which aspects of the site geology and core chronology are strictly necessary for the reader to understand and assess the findings, and to condense or relocate the remaining detail accordingly. Information that is not linked to the discussion or conclusions may be better suited for a supplementary appendix.Results
The Results section contains several writing and formatting issues that need to be addressed throughout. First, punctuation errors affect readability and should be carefully reviewed. Second, the manuscript is inconsistent in how ages are reported: in some instances the authors use "yr BP" while in others they use "cal yr BP". This must be standardised throughout the entire manuscript; given the nature of the chronological data presented, "cal yr BP" is the appropriate and preferred convention. Third, numerical ranges are separated with a hyphen instead of an em dash, which does not follow standard scientific writing conventions (e.g., "3000–2500 cal yr BP" rather than "3000-2500 cal yr BP"). The authors should apply this correction consistently across the manuscript. Fourth, genus and species names are not consistently written in italics, as required by standard taxonomic nomenclature; the authors should carefully check that all scientific names are italicised throughout the text, tables, and figure captions. More broadly, the Results section requires careful revision, and the authors may wish to consider professional English-language editing before resubmission.Discussion
The final paragraphs of the Discussion section read more as conclusions than as discussion. Content such as projections for future paleoenvironmental studies, a synthesis of the chronological framework's reliability, and the broader implications of local drivers for community adaptation and ecological refugia belongs in the Conclusions section. The Discussion should focus on interpreting the results in light of the existing literature and addressing the study's limitations, rather than anticipating closing statements. The authors are encouraged to restructure this content accordingly, ensuring that each section fulfils its distinct role within the manuscript.Conclusions
The Conclusions section requires significant revision. As written, it largely repeats the results rather than synthesising their meaning and significance. A conclusion should not restate what was found but rather interpret what those findings mean collectively in light of the research question and objectives.
Specifically, the authors should explicitly address whether the study achieved its main aim, distinguish local influences from broader regional processes affecting aquatic communities, and state the degree to which they accomplished this. This is the central question of the work, and the Conclusions section is precisely where the reader expects a direct and clear answer.
Furthermore, the section should discuss the broader implications of these findings for Andean-Altiplano paleolimnology and for our understanding of the environmental drivers shaping high-altitude lake ecosystems over the last 3000 cal yr BP. If relevant, the authors may also acknowledge the limitations of the multiproxy approach applied here and suggest directions for future research.
In its current form, the Conclusions section does not fulfil its role as the manuscript's closing argument, which weakens the overall impact of the work.Additional Comments
Further specific comments, annotations, and suggestions are provided directly in the reviewed PDF attached to this evaluation.All the best
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This ms presents peleoenvironmental changes from two sediment cores collected in high mountain lakes of the Central Andean Altiplano in Chile. Changes in water level are reconstructed from multiproxy analyses (geochemistry, magnetic properties, pollen assemblages, benthic macroinvertebrates). Chronology was obtained from radiocarbon dating with 4 measures for the first lake dated to 900 cal BP and 6 measures for the second lake dated to 3000 cal BP. Results show phases of increased basin run off and low terrigeneous input while an increase in sedimentation rate suggests additional sources like aeolian deposits on the first core shown by change in magnetic susceptibility.
The data presented by the authors are rare, located in a remote area, and of excellent quality. However, I regret that the authors limit themselves to the data without delving into the explanations that would allow for a better understanding of the significance of the changes described. Furthermore, the scientific question justifying this work is not clearly formulated.
For example, it is not clearly established when the wetter phase, the drier phase, and the phase involving aeolian inputs occur, which makes understanding the situation as a whole very complex.Furthermore, we lack all the information that would enable us to understand the modern environment and depositional conditions of these lakes.
Below, you will find some detailed comments—which I hope are constructive—intended to help the authors revise the manuscript.
ABSTRACT
-The abstract is very factual and lacks detail in the presentation of the results (e.g., the chronology).-The results of the pollen analyses are not mentioned.-Finally, it is unclear whether the observations align with those recorded at a more regional scale.
MATERIAL AND METHODSAmong the elements I most lacked in approaching this work, one might cite:descriptions of the vegetation and pollen assemblages—in conjunction with pollen-vegetation calibration studies—, information on the region's climate, and a discussion of the chronological and spatial context of the area or its immediate surroundings.
RESULTS
Furthermore, I regret that the geochemical results—which lie at the heart of this study—are presented in a conventional format, without using better practices for the processing and interpretation of bulk inorganic geochemical data. Log-ratio transformation is essential for the rigorous statistical analysis of geochemical datasets. Furthermore, an accurate interpretation of inorganic geochemical data requires a sound understanding of the sediment's main constituents (organic matter, biogenic silica, carbonates, lithogenic particles) as well as its mineralogical assemblages.
See for instance Bertrand, S., Tjallingii, R., Kylander, M. E., Wilhelm, B., Roberts, S. J., Arnaud, F., et al.: Inorganic geochemistry of Lake sediments: A review of analytical techniques and guidelines for data interpretation, Earth-Science Reviews, 249, 104639, doi.org/10.1016/j.earscirev.2023.104639, 2024.
Above all, we need a single synthetic figure showing the main results of the multiproxy analyses (geochemistry, pollen, benthic macro invertebrates), a table with information on the radiocarbon dates: laboratory where the measures were performed, lab number, sample depth, C14 dates, calibrated ages.
MISCELLANEOUS
-The description of the geochemical results is too long.
-The pollen diagram does not show any pollen zones why?
In addition, it is extremely difficult to follow the results without references to pollen calibration and vegetation physiognomies of the study area.
Discussion:
-The discussion is very difficult to follow. -Indicate the regional and local phases of the observed changes, clearly specifying the depth and age, and represent them in a figure.
-To which period do the episodes suggesting the influence of high-energy clastic input correspond? (line 379)
Line 382: What is the duration of the event? What is the thickness of the associated sediments?-Where is it located on your figures?-When did the aeolian deposit form? What are the hypotheses explaining its origin?
-What are the main changes observed in the study area? When?
-Show on a map the location of the records discussed in the text