LEROY POFF, in Rivers of North America, 2005 Invertebrates The lower river reservoirs also have been colonized by estuarine amphipods.ĭEAN W. Today, a rich phytoplankton community and abundant fine particulate organic matter support a dominant macroinvertebrate population of netspinning caddisflies ( Hydropsyche and Cheumatopsyche), chironomids, and other filter-feeding organisms (mollusks), although many invertebrate genera found prior to dam closures upstream and downstream from the Hanford Reach are no longer found. Considering that the Hanford Reach remains similar to the historic condition of the rest of the main stem, it seems likely that the main-stem river historically throughout its length contained a rich food web that supported substantial salmon production. Other taxa found since 1951 include stoneflies ( Arcynopteryxa), mollusks ( Pisidium, Fluminicola, Asiatic clam, western pearlshell), and crustaceans ( Corophium, Pacifastacus, Gammarus). Additional caddisflies collected since 1951 include Brachycentrus, Glossosoma, Hydroptila, Lepidostoma, Leptocella, and Rhyacophila, and additional mayflies include Ephemera, Ephoron, Hexagenia, Heptagenia, Stenonema, and Tricorythodes. Net-spinning caddisflies ( Hydropsyche, Cheumatopsyche), ephemerellid ( Ephemerella) mayflies, three genera of stoneflies ( Isogenus, Perlodes, Pteronarcys), and chironomid midges were notably abundant. Newell (2003) listed 145 macroinvertebrate taxa that have been identified from the free-flowing Hanford Reach since 1951, although far fewer are present today. SNYDER, in Rivers of North America, 2005 Invertebrates
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