USGS-NAWQA: NAWQA Algae 1993: Algal sample collection in streams
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Official Method Name
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Methods for collecting algal samples as part of the National Water-Quality Assessment Program |
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Current Revision
| 1993 |
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Media
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Biological |
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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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Brief Method Summary
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Benthic algae (periphyton) and phytoplankton communities are characterized in the U.S. Geological Survey's National Water-Quality Assessment Program as part of an integrated physical, chemical, and biological assessment of the Nation's water quality. This multidisciplinary approach provides multiple lines of evidence for evaluating water-quality status and trends, and for refining an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. Water quality can be characterized by evaluating the results of qualitative and quantitative measurements of the algal community. Qualitative periphyton samples are collected to develop of list of taxa present in the sampling reach. Quantitative periphyton samples are collected to measure algal community structure within selected habitats. These samples of benthic algal communities are collected from natural substrates, using the sampling methods that are most appropriate for the habitat conditions. Phytoplankton samples may be collected in large nonwadeable streams and rivers to meet specific program objectives. Estimates of algal biomass (chlorophyll content and ash-free dry mass) also are optional measures that may be useful for interpreting water-quality conditions. A nationally consistent approach provides guidance on site, reach, and habitat selection, as well as information on methods and equipment for qualitative and quantitative sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data locally, regionally, and nationally.
This protocol and its methods has been superseded by: Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program (2002) |
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Scope and Application
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This method describes the USGS National Water-Quality Assessment Program (NAWQA) protocol for algae sampling, specifically Depositional Targeted Habitat (ADTH). This method describes how to collect algal samples for 5 habitat types: epilithic, epidendric, epiphytic, epipsammic, and epipelic. It is one protocol of the larger USGS Open-File Report 02-150. DTH sampling protocols are described in section 4.3 of the report. The full report provides revised protocols for sampling algal, invertebrate, and fish communities as part of the NAWQA Program. The protocols describe required methods for collecting and processing biological samples. This report revises the original NAWQA protocols for algae (Porter and others, 1993), invertebrates (Cuffney and others, 1993), and fish (Meador and others, 1993; Walsh and Meador, 1998). |
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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 sample 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 can not exceed 475 mL to allow for the addition of formaldehyde. |
