Unearthing the effects of European-American settlement on a northeast Ohio kettle lake through diatom stratigraphy

Justine Paul Berina

Name: Justine Paul Berina
Major: Geology
Advisors: Mark Wilson & Greg Wiles

Best Explained Technical Project

Recently, wetland conservation has highlighted the necessity for assessing limnological changes following European-American settlement. A prior study at Brown’s Lake (northeast Ohio) identified a stratigraphic sequence that shows an abrupt transition from organic-rich muds to several centimeters of a bright loess layer, then a recovery to organic-rich sediments near the top. Based on 210Pb dates, the loess deposition occurred before 1846 CE, when a growing population cleared trees and farmed intensively. Likewise, organics had recovered after 1950 CE, when people abandoned farmland and practiced conservation tillage. However, the effects of settlement on limnology are poorly known. Diatoms (microscopic algae; class Bacillariophyceae) respond to modifications in water quality and habitat parameters, and siliceous cell walls enable preservation in sediments as fossils. Therefore, a diatom stratigraphy can record the lake’s limnological history. A 1-m sediment core was extracted using a modified-Livingstone sampler and dated using AMS radiocarbon dating. A total of 380 cells from the core were analyzed. The data reveal shifting relative abundances that coincide with settlement activities. Before 880 CE, Thalassiosira sp., a non-motile genus, is dominant, making up 22.1% of diatoms. Between 880 CE and 1950 CE, Achnanthidium sp., a motile genus, is abundant, making up 25.0% of diatoms. It has been noted that the replacement of planktonic genera by diatoms capable of moving through fine sediments suggests a time of excess siltation. From 1950 CE to the present-day, Cyclotella sp., a non-motile genus, is dominant, making up 30% of diatoms. Despite these associations, the data cannot provide evidence of a cause-and-effect relationship due to confounding variables (e.g., climate, habitat availability, and structures), errors, and limitations. This study offers the first catalog of historical and modern diatom assemblages at Brown’s Lake to support conservation initiatives.

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Posted in Comments Enabled, Independent Study, Symposium 2022.

8 responses to “Unearthing the effects of European-American settlement on a northeast Ohio kettle lake through diatom stratigraphy”

  1. David McConnell says:

    Congratulations, Justine, on a great presentation and on completing IS. I hope your post-graduation plans are still shaping up nicely!

  2. Bill Meurer says:

    Great research Justin – well done and presented. Just a couple of technical questions. Do you know the lake’s hydrologic balance over time (underfilled, balanced, vs. overfilled)? Underfilled lakes are subject t significant chemical shifts and this could impact the foram populations. There is apparent jump in the sediment accumulation rate from that between the first two ages (~9.5cm/ka) to that between the second and last ages (~50cm/ka). This change occurs before the proposed impact of settlement. Is it possible that the system was already undergoing a change and that settlement impacts were subsidiary and not the primary driver in the transition from anoxic to oxygen-rich bottom water in the lake? Food for thought. Good luck with your future endeavors.

  3. Justine Paul Berina says:

    Professor McConnell, I appreciate you for visiting our project. After Wooster, I’ll begin my geology career in Virginia. My experiences at the college have been helping me fulfill my lifelong goals.

  4. Justine Paul Berina says:

    Bill Meurer, I appreciate your detailed feedback and insights into our project. I don’t know the lake’s hydrological balance through time, but I can relay this question to explore to the next group of seniors. Sedimentation increased rapidly for several centuries before 1800 CE. We hope to investigate other unknown causes (natural and anthropogenic) leading to this change.

  5. Jennifer Faust says:

    Congratulations on your Best Explanation prize! It is well deserved.

  6. Justine Paul Berina says:

    Professor Faust, thank you for the kind words!

  7. Candace Chenoweth says:

    JP – I love the polished way in which you presented your results. You are a true scientist!!

  8. Justine Paul Berina says:

    Candace, I appreciate your tremendous support. I’ll keep up the great work; thank you very much!