Michael Hoffman

Advisor: Dr. Stanley Dodson

M.S. Zoology, 2004:  Effect of land use on zooplankton biodiversity.

An understanding of the relative roles of lake size, primary productivity and watershed development is crucial to understanding biodiversity in lakes. We analyzed data from 41 well-studied world-lakes to find that both natural drivers (lake size and productivity) and an anthropogenic driver (% watershed development) are predictors of zooplankton biodiversity . Species richness and lake size were related positively (monotonic) in the entire lake dataset (r2 = 0.35), not at all in the pristine lakes (in undeveloped watersheds), and positively for lakes in developed watersheds (r2 = 0.58). Richness and productivity were related unimodally in the entire lake dataset (r2 = 0.30), positive-linear in the pristine lakes (r2 = 0.69), and negative-linear in the developed lakes (r2 = 0.12). Degree of watershed development (quadratic model) was the best single descriptor of richness for all lakes (r2 = 0.42) and for developed lakes (r2 = 0.65). Our best model (r2=0.69) for all 41 lakes included linear lake size, quadratic productivity, and quadratic development terms. The best model (r2=0.69) for undeveloped lakes included only a linear productivity term. The best model for lakes in developed watersheds (r2=0.79) included positive linear lake size, negative linear productivity, and quadratic development terms.