Using Aquatic Macroinvertebrates as Indicators of Stream Flow ...

Amphipoda), water mites (subclass Hydracarina), and aquatic sowbugs (order Isopoda). Aninexpensive, portable, waterproof field guide such as The Xerces Society Macroinvertebrates ofthe Pacific Northwest (2003) and a hand lens is needed to identify organisms to family level.Ideally, we recommend that a macroinvertebrate field guide be developed specifically toaccompany this stream duration assessment protocol. Such a guide could be targeted at thespecific needs of practitioners, such as identifying the pupal forms of common aquaticmacroinvertebrates to family, distinguishing between larvae of different families that are similarin appearance (i.e. mosquito vs. midge), and recognizing common semi-aquatic or terrestrialinvertebrates that are most likely to invade a dry channel.Users should be aware that not all taxa listed as flow indicators are present in every correlatedstream class. For example, a perennial stream may lack Juga snails, depending on the streamlocation, elevation, and flow rate. By the same token, many families of caddisflies that do notconstruct portable cases may complete development successfully in an intermittent stream butleave no trace of their presence once development is completed, unlike the substantial cases thatcan be left behind by limnephilid caddisflies. However, the presence of a number of the differentindicators for each specific stream class below, in combination with the absence or very lowlevel of indicators for alternative stream classes, should provide a more robust estimation ofstream duration.Macroinvertebrates as indicators of stream flow duration,The Xerces Society for Invertebrate Conservation15