Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Geography

Supervisor

Dr. Katrina Moser

Abstract

Relationships between climate variables, lake characteristics and diatom community composition were determined for five lakes in the Uinta Mountains, Utah (USA) from spring 2010 to autumn 2013 to provide information to help predict the effects of climate change on lake ecosystems. Surface water temperatures increased with decreasing elevation although microclimates affected this relationship. Deeper water temperatures increased or stayed the same with increasing elevation, probably due to greater transparency or convective heating. Total phosphorus (TP) and chl a concentrations decreased in the spring/summer with warmer fall/winter temperatures, and nitrates in the spring increased with increased fall/winter precipitation. A significant correlation between chl a and TP suggests algal production is limited by phosphorus in the spring. High elevation lakes were characterized by greater relative abundances of planktonic diatoms, mainly Asterionella formosa, Fragilaria tenera, F. nanana and small Cyclotella species, than low elevation lakes due to greater nutrient availability.