The planktonic, periphytic (both submerged and emergent vegetation) and benthic rotifer communities of an alkaline freshwater marsh were studied from May 1979-May 1980. Of 32 species of rotifers recorded, 17 were common.Rotaria rotatoriadominated the four habitats examined throughout the entire study period. A succession of several other species appeared as dominants in concert withRotaria rotatoriaat various times of the year, in various habitats. Significant coefficients of correlation (p ≤.01) were found among 9 dominant species, also grouped by factor analysis as responsible for 53.1% of the community variance. Several physical-chemical characteristics were found to correlate significantly (p ≤.05) with the marsh rotifer community population dynamics. Differences in-diversity and population sizes among the benthic, periphytic, and planktonic communities were found.