Table 1. <strong>Stream</strong> flow duration indicatorsPerennial Intermittent EphemeralJuga spp. (pluerocerid snail)Freshwater mussels(Margaritiferidae, Unionidae),but less likely in small highgradientstreamsLarvae/pupae <strong>of</strong>:Limnephilidae (Northerncaddisfly)Larvae/pupae <strong>of</strong>:Culicidae (mosquito)Larvae or pupae <strong>of</strong>:Philopotamidae (finger-netcaddisfly)Hydropsychidae (net-spinningcaddisfly)Rhyacophilidae (freelivingcaddisfly)Glossosomatidae (saddle c<strong>as</strong>emakercaddisfly), esp. inforested headwater streamsNymphs <strong>of</strong>:Pteronarcyidae (giant stonefly)Perlidae (golden stonefly)Larvae <strong>of</strong>:Elmidae (riffle beetle),Psephenidae (water penny), esp.in e<strong>as</strong>tern regionsLarvae/nymphs <strong>of</strong>:Gomphidae (clubtail dragonfly)Corduleg<strong>as</strong>tridae (biddies)Calopterygidae (broadwingeddamselfly)esp. in larger, higher-orderNymphs <strong>of</strong>:Capniidae (small winterstonefly)Nemouridae (forestfly)Larvae/adults <strong>of</strong>:Dytiscidae (predaceous divingbeetle)Hydrophilidae (waterscavenger beetle)Nymphs/adults <strong>of</strong>:Notonectidae (backswimmers)Larvae/nymphs <strong>of</strong>:Lestidae (spread-wingeddamselfly)streams in e<strong>as</strong>tern ORNymphs <strong>of</strong> >4 different families<strong>of</strong> Ephemeroptera (mayfly)Greatest taxa diversity Intermediate taxa diversity Low taxa diversityHighest EPT Intermediate EPT Low/no EPT (exception islimnephilid c<strong>as</strong>es in a drychannel, which wouldindicate intermittent flow)<strong>Macroinvertebrates</strong> <strong>as</strong> indicators <strong>of</strong> stream flow duration,The Xerces Society for Invertebrate Conservation16
ScoringThe current Oregon Draft <strong>Stream</strong> Assessment method uses a character rating system <strong>of</strong> absent(0), weak (1), moderate (2), or strong (3), with higher scores correlating with incre<strong>as</strong>ed flowpermanence. In the biological <strong>as</strong>sessment portion <strong>of</strong> the method, fish and macroinvertebrates aregiven the same weight, with possible scores ranging from 0-3, where<strong>as</strong> the score from amphibianmonitoring is weighted less heavily (0-1.5). Because <strong>of</strong> the uncertainties inherent in usingmacroinvertebrate families <strong>as</strong> indicators, we recommend that macroinvertebrates receive thesame final scoring weight <strong>as</strong> amphibians in the final <strong>as</strong>sessment, i.e. 0-1.5.The Oregon Draft method also incorporates levels <strong>of</strong> search effort into scoring. We recommendinstead that a standardized number <strong>of</strong> 6 samples encomp<strong>as</strong>sing all habitats within a reach betaken at each site. Alternatively, a standardized macroinvertebrate search time <strong>of</strong> 30 minutes canbe used, during which period all possible different habitat types within the reach are sampled(see Field Methodology below), although this will not allow <strong>as</strong> thorough a sampling <strong>of</strong> the reachto be done.Recommendations for some metrics have been made with the intended end users <strong>of</strong> the protocolin mind, specifically for the expected numbers <strong>of</strong> different aquatic invertebrate taxa found withinthe reach. For example, we recommend that if practitioners find 15 or more different taxa (i.e.families, subcl<strong>as</strong>ses, or orders, where applicable) within a reach, it is considered a strongindicator <strong>of</strong> perennial flow. An individual with extensive experience in aquatic entomology andstream sampling conducting a scientific study is would be more likely to find at le<strong>as</strong>t 20 differenttaxa, depending on the time <strong>of</strong> year. However, practitioners using this <strong>as</strong>sessment method willmostly lack this expertise, and a lack <strong>of</strong> experience in aquatic entomology may also cause usersto overlook small or cryptic individuals. In addition, regardless <strong>of</strong> whether six samples per reachare taken or if sampling is conducted for 30 minutes in a reach, it is very unlikely that allpossible taxa will be found. The constraints on time and expertise inherent in this techniqueresult in more <strong>of</strong> a sub-sampling <strong>of</strong> each reach, and have therefore led us to recommend slightlylower numbers <strong>of</strong> taxa <strong>as</strong> stream duration cl<strong>as</strong>s indicators. Modifications to this metric may bemade b<strong>as</strong>ed on the results <strong>of</strong> field testing.For macroinvertebrate scoring, the number and identity <strong>of</strong> all taxa collected is recorded, so thatthe number <strong>of</strong> different taxa and % EPT can be calculated. Specific organisms whose identity isin question can be preserved and identified later with additional guides and expertise if needed(<strong>as</strong> described in Field methodology, pg. 20). The following rating scale should be used:Strong (1.5):>15 different aquatic macroinvertebrate taxa are found within the reachOR1 or more members <strong>of</strong> the families <strong>of</strong> perennial indicator taxa (Table 1) are foundOR>4 different families <strong>of</strong> Ephemeroptera (mayfly) are foundOR>5 different families <strong>of</strong> EPT are foundOR>40% <strong>of</strong> total taxa are EPT<strong>Macroinvertebrates</strong> <strong>as</strong> indicators <strong>of</strong> stream flow duration,The Xerces Society for Invertebrate Conservation17
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