We evaluated the efficacy of different field sampling approaches for volunteers sampling
macroinvertebrates in low-gradient streams.We used a series of analytical metrics to compare results using the
Environmental Protection Agency (EPA) multihabitat, the Minnesota Pollution Control Agency multihabitat,
and EPA single-habitat sampling protocols. We also investigated the effect of 2 scenarios in which volunteers
fail to follow (and potentially bias) the widely used EPA multihabitat protocol by including either more snag
and vegetated banks or more run and riffle habitat than prescribed by the protocol. We collected jab samples
from cobble, snags, vegetated banks, submerged macrophytes, and sand in 4 contiguous 125-m reaches in an
Anoka sand-plain stream in Minnesota. We identified up to 100 macroinvertebrates in each jab sample to
family. We subjected a parent population of 40 jab samples/reach to a bootstrap analysis to sample and create
metric or index scores 100 times without replacement for each of the 3 volunteer sampling methods and 2
biased scenarios. The EPA multihabitat protocol and the biased scenario in which woody debris and bank
vegetation were oversampled yielded the highest diversity of organisms, whereas the biased scenario in which
riffle and run habitats were oversampled yielded the lowest diversity. The EPA multihabitat protocol used
correctly was more likely to indicate ‘‘good’’ water quality (on the basis of the EPA muddy-bottom narrative
assessment tool designed for volunteers) than either biased sampling scenario. This result illustrates that poor
field methods could result in underestimation of water quality.
Nerbonne, Julia, F.; Ward, Brad; Ollila, Ann; Williams, Mary; Vondracek, Bruce.
Effect of sampling protocol and volunteer bias when sampling for macroinvertebrates.
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