Great Basin Naturalist


Colonization of macroinvertebrates was assessed in a stream impacted by inputs of fine sediments. Colonization was examined at the stream surface and within the hyporheos with Whitlock-Vibert (W-V) boxes. Hyporheic areas accumulated much greater amounts of all size categories of sediment. No significant difference was observed in the amounts of organic matter accumulated at either depth. Only 150-μm sediment had significant effects on macroinvertebrate total numbers and number of taxa. Total numbers of invertebrates at 30 cm were only 20% of those at the surface. Canonical correspondence of analysis indicated that the strongest influence on macroinvertebrates colonizing W-V boxes at the surface was stream size and secondarily fine sediments. Within the hyporheos, abundance of fine sediment was the dominant influence on macroinvertebrate assemblages. Impacts of sedimentation on hyporheic environments can have significant and persistent impacts on streams.