USGS-NAWQA: NAWQA Algal RTH 2002 (Wade): Algal Sample Collection at Richest-Targeted Habitat (RTH) in wadeable streams by SG-92 (and other instruments)
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Official Method Name
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Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program |
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Current Revision
| 2002-Supersedes USGS Open-File Report 93-409 (algal) |
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Media
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Biological (Waterbody type - Wadeable stream) |
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Instrumentation
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Algal sampling devices |
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Method Subcategory
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Population/Community |
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Method Source
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Citation
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Protocol
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USGS NAWQA 2002 Eco Protocols - Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program |
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Brief Method Summary
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Richest-targeted habitat (RTH)—A targeted habitat (usually a riffle or woody snag where the taxonomically richest algal or invertebrate community is theoretically located) identified in a reach from which discrete collections of algae or invertebrates are taken and later combined to form a composite sample. The composited sample is referred to as a "RTH sample." This method describes how to collect algal community samples for 5 habitat types: epilithic, epidendric, epiphytic, epipsammic, and epipelic. Epilithic habitats are sampled by using one of three methods depending on the types of rock substrate being sampled. The SG-92 is a modified syringe-sampling device and performs best on smooth cobble surfaces with moderate-to-dense coverage of microalgal periphyton. The "top-rock scrape" method is used for sampling irregular cobble surfaces or when cobble surfaces have sparse periphyton coverage. The gravel sampler is used when sampling microalgal periphyton attached to gravel substrates. |
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Scope and Application
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This method describes how to collect algal community samples for 5 habitat types: epilithic, epidendric, epiphytic, epipsammic, and epipelic. |
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Applicable Concentration Range
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Interferences
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Quality Control Requirements
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Additional (10–20 percent) subsample splits can be prepared for CHL A, AFDM or POC, and ID subsamples to evaluate precision of subsample preparation and laboratory analysis. Replicated sampling within the reach can be used to evaluate the variance in algal community structure. |
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Sample Handling
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Preserve the ID subsample with a sufficient volume of buffered formaldehyde according to the method report table to obtain a final concentration of 3 to 5 percent buffered formalin. Ship in coolers containing dry ice and frozen CHL A and AFDM or POC subsample filters. Coolers should be shipped within a day or two after the subsamples are prepared because of a 25-day holding-time limit on the subsamples. Subsamples can be temporarily stored in freezers (at -20°C) at the field office over weekends. |
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Maximum Holding Time
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25 days |
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Relative Cost
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Unknown |
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Sample Preparation Methods
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Total sample volume cannot exceed 475 mL to allow for the addition of formaldehyde. |
