ASSOCIATIONS BETWEEN HYDROGEOMORPHIC CHARACTERISTICS AND PRIMARY PRODUCER DISTRIBUTIONS IN THE UPPER CLARK FORK RIVER, MONTANA
A downstream trend in dominance from macroalgae (primarily Cladophora glomerata) to various macrophyte species was investigated through a longitudinal survey of a 40-km reach of the Upper Clark Fork River, Montana. We surveyed transects every 2 -km along to determine taxonomic identities and distributions of macrophytes and macroalgae relative to fundamental physical, chemical, and hydrologic variables. We measured water velocity, depth, and sediment size distribution at the patch level to relate hydrogeomorphic characteristics to presence of macrophytes or macroalgae. Predominantly, Cladophora was associated with sediment patches consisting of fairly large proportions of very coarse (mean= 39%) and coarse gravels (mean= 18%). Macrophyte species (Potamogeton pectinatus, Elodia canadensis, and Ceratophyllum demersum) were associated with finer-grained sediments. Sediment size distribution among macrophyte patches varied by species type, likely due to differences in growth habit. Spatial variation in the hydrogeomorphic template has implications for the identity and abundance of primary producers in this well-lit, productive river.
Carly Andlauer (Primary Presenter/Author), University of Montana, email@example.com;
H. Maurice Valett (Co-Presenter/Co-Author), University of Montana, Division of Biological Sciences, firstname.lastname@example.org;