ESTIMATION OF FINE PARTICULATE TRANSPORT IN STREAMS USING POLLEN AS A SESTON ANALOG

We describe a new method for estimating the distance that fine particulate organic matter (FPOM) is transported in streams. Corn pollen (diameter = 87-mu-m, rho = 1092 kg/m3) was injected into Dry Brook, a 2nd-order stream in Allegany State Park, New York. Loss of pollen from the water column was measured by filtering pollen from approximately 250-mL grab samples, staining with basic function, and counting. Loss rates were fit to an exponential decay function; mean travel distances on three release dates ranged from 122 to 190 m, consistent with predictions of a model that assumes particle loss is proportional to the settling velocity of a particle in still water and the depth of the water column. Pollen, as a seston analog, would provide a comparative tool to measure transport in streams that differ in critical geomorphic and hydraulic characteristics. This technique can be applied to questions on how bed structure and near-bed flow affect retention and transport of seston, and on the importance of still water settling velocities, stream temperature, and biological uptake in determining FPOM travel distances.