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Sample Collection
Standardization of field methods is necessary to establish the validity and
reliability of biological data used in an assessment. A lack of standardization
results in the use of diverse methods, which ultimately yields conflicting
information. Thorough training of investigators, coupled with rigorous certification
processes, enhances the ability to provide a consistent unit of effort. Strong
oversight of activities and leadership of apprentice professionals are critical.
Standardization is especially important when information will be used in later
trend analysis. Evaluation of methods is necessary to ensure the sampling
techniques are appropriate for the aquatic ecosystem under study. Considerations
for field sampling of macroinvertebrates, fish, algae, and aquatic macrophytes
include habitat type to be sampled, gear type, number of samples required,
reach length, and field methods. Most fish and macrophyte assessments are
carried out in the field and do not require extensive laboratory analysis.
However, vouchering of these organisms is a necessary quality control (QC)
function to verify accurate and consistent identifications.
Considerations for laboratory processing of macroinvertebrate and algal samples include proper preservation, labeling, transport, and transfer from field personnel to lab personnel. The development of standard operating procedures (SOPs) for field and laboratory methods must include an effective quality assurance (QA) program with QC checks. The development of an effective QA plan is essential to the success of the bioassessment program. It should assign responsibility, define personnel qualifications, establish protocols, define preventative and corrective action, provide information tracking, and ensure that study objectives are met. QA plans are especially important to regulate performance and maintain data integrity. To minimize bias, reduce error, and maintain a high level of data integrity as prescribed by the measurement quality objectives (MQOs) (see Technical Element 10, Ecological Attributes), the SOPs and QA/QC plan must identify the specific procedures for all aspects of the biological program. This information should be available for other parties to use as a reference in developing compatible monitoring projects. USEPA has published a generic quality assurance project plan (QAPP) (100pp, 3894K, About PDF)guide for programs using assemblage-level biological assessment in wadeable streams and rivers.
For more information, please visit Sampling Protocols in Lessons Learned for Bioassessment as well as our Web page on sample collection for fish and benthic macroinvertebrates.
Also, there are a variety of methods documents covering sample collection on our publications page including EPA's Rapid Bioassessment Protocol discussion for collecting fish, benthic macroinvertebrates, and periphyton.