Brian Weigel

Advisor: Stanley Dodson

Ph.D Zoology, 2001: Detecting and regulating human distrubance for improved integrity of surface waters.

I developed macroinvertebrate-based indexes of biotic integrity (IBI) for detecting human disturbance in watersheds of Wisconsin and west-central Mexico. The multimetric assessment tools were designed for monitoring pollution and developing biological criteria to protect aquatic ecosystems. Using the Lake Mendota watershed in south-central Wisconsin, I performed comparative analyses of upland regulatory policies intended to curb agricultural runoff.

Wisconsin required separate IBI models for the north, southwest, and combined central-southeast region due to geomorphological differences. The Wisconsin IBI development process was unique in 1) selecting base metrics a priori, 2) incorporating watershed landcover into a quantification of human disturbance, 3) weighting component local and watershed scale metrics objectively to characterize human disturbance in a biologically meaningful way, and 4) weighting macroinvertebrate metrics objectively to detect human disturbance. Using canonical correlation analysis, I identified the relationship between a set of macroinvertebrate assemblage variables and a set of human disturbance variables simultaneously. The procedure weighted individual metrics objectively to give the optimal correlation between macroinvertebrates and disturbance, providing an IBI equation. Testing the IBIs with independent data indicated the macroinvertebrates were strong predictors of disturbance.

Despite extraordinary differences in natural environmental qualities, biotic characteristics, and human disturbance types from where the first IBIs were developed, I tailored an IBI to streams of west-central Mexico. Restoration efforts to improve stream and watershed conditions have been hampered by a lack of clear standards against which to judge the degree of an trends in environmental degradation. I describe the successful development and validation of an IBI designed to provide such standards.

Regulatory agencies have limited resources to design and enforce policy, necessitating research assistance in prioritizing agricultural pollution reduction efforts. I compared the farms that would be regulated under threshold farm size management schemes and targeted regulatory approaches. The phosphorus index targeted farms that contribute the most pollution whereas the threshold approaches missed substantial areas.

Collectively the dissertation illustrates advances in detecting how human activities impact freshwater ecosystems and their inhabitants, especially stream macroinvertebrates. It also demonstrates how this understanding can aid management decisions designed to protect the integrity of surface waters.