Date of Award


Publication Type

Master Thesis

Degree Name



Great Lakes Institute for Environmental Research

First Advisor

Haffner, G.D. (GLIER Environmental Science)


Health Sciences, Toxicology.



Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


Factors regulating composition and relative abundance in phytoplankton communities were investigated in an ancient lake with a highly endemic food web. Lake Matano has genera diversity (21) similar to tropical lakes, but low phytoplankton biomass (0.0162 ug/L). Vertical mixing physically limits primary production (42% Zeu:Zm); phytoplankton are moved below the euphotic zone. Macronutrient concentrations (0.30 umol/L N, 0.13 umol/L P) are low. Nutrient bioassays used N and P (30-320 umol/L individually, 60:5-1920:160 umol/L N:P combined). After 16 days, no significant (p > 0.05) changes in relative abundance and no biologically significant changes in phytoplankton biomass occurred. CHU-10 growth media cultivation, however, significantly increased chl-a. Analysis identified Cr (0.14 umol/L) above a threshold to restrict algal growth (0.12 umol/L) and Mo (0.0005 umol/L) below requirements by most aquatic life (0.008 umol/L). Therefore, physical (mixing) and chemical (toxicity, micronutrient) factors are concluded to limit composition and relative abundance of phytoplankton in Matano.