Date of Award
Summer 8-1-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Earth & Environmental Systems
First Advisor
Jeffery R. Stone
Second Advisor
Jennifer C. Latimer
Third Advisor
Karlyn Westover
Abstract
Lake Tanganyika is one of the world's largest freshwater ecosystems, supporting rich aquatic biodiversity and providing several ecosystem services to surrounding communities. Environmental changes such as rising lake surface temperatures, pollution, and land-use alterations threaten the lake’s sustainability. This research examines spatial and temporal variations in nutrient dynamics and primary productivity of Lake Tanganyika using diatom assemblages from multiple locations. Our findings indicate reduced nutrient levels and longer stratification periods in the lake’s central basin during most of the Common Era, as indicated by a remarkable increase in the relative abundance of long, needle-shaped planktonic Nitzschia species. In the southern basin of the lake, there was a notable drop in diatom concentrations after ~1850 CE in both the nearshore and offshore records. The assemblages dominated by long, needle-shaped planktonic Nitzschia species in the nearshore region, and their low preservation in the offshore region during the last two centuries, indicate less frequent upwelling events and reduced nutrient levels in the southern basin of the lake. An increase in the abundances and concentrations of small, centric euplanktonic diatoms after ~2015 CE in both the nearshore and offshore records suggests increased conductivity, which might result from nutrient loading from the nearby watersheds. We have successfully identified and described one new benthic diatom, “Placoneis jovanovskiana”, from the southern basin. However, many diatoms remain unidentified to the species level and likely are undescribed. Our findings emphasize changes in diatom concentrations, primary productivity, and nutrient levels across time and space during the Common Era. They form the baseline for developing a sustainable lake conservation and management plan and highlight the need to develop integrated plans for the lake and the lake-dependent community’s resilience towards environmental changes.
Recommended Citation
Adhikari, Sristika, "Paleolimnology and Diatom Taxonomy From Lake Tanganyika" (2026). All-Inclusive List of Electronic Theses and Dissertations. 3815.
https://scholars.indianastate.edu/etds/3815