Great Basin Naturalist


Recent bottom sediments of eight lakes and reservoirs in northeastern Utah were examined. One hundred and sixty-four diatom taxa were identified and their relative abundances determined. Seven stand associations were evident by cluster analysis of similarity indices. These association patterns mirrored trophic status of the waters. Shannon–Wiener species diversity values were also determined. The diversities fell in patterns that were similar to the stand associations determined by cluster analysis. The most prevalent diatom taxa encountered in this study were found mostly in eutrophic waters. These taxa included Stephanodiscus astraea, Stephanodiscus astraea var. minutula, Asterionella formosa, and Fragilaria crotonensis. A wide variety of other taxa dominated various mesotrophic and oligotrophic sites.