Density Compensation in Umbra‐Perca Fish Assemblages of Northern Wisconsin Lakes

• DOI: 10.2307/1940391
• Publication Date: 2006-05-09T13:51:02Z
• Authors: William M. Tonn
• Keywords: Dominance (genetics); Population density

Small, shallow seepage lakes in northern Wisconsin that have both low winter oxygen concentrations and pH possess depauperate fish assemblages containing primarily or exclusively central mudminnows, Umbra limi, yellow perch, perca flavescens. Six times during three years I determined the total densities of five by mark—recapture catch—per—effort methods. The richness these varied from one to species a nested pattern. While seasonal variations density occurred within among due growth, mortality, recruitment, overall were independent richness. pattern, called complete compensation, suggests are expressions lakes' similar abilities support interact rather than being independent. An intense negative correlation between perch mudminnow was found, suggesting strong interspecific population dominance over mudminnows. There also indirect evidence competition (exploitation interference) predation regulate populations when co—occur. Because unpredictably variable time space, conclusions single censuses would been unreliable. exercise simulating each class showed less one—half such produced pattern compensation observed field study. In general, my results idea relative importance factors determine community structure, even themselves, can differ not only assemblage at any time, but season year assemblage.