The Value of Long-Term Stream Invertebrate Data Collected by Citizen Scientists

The purpose of this investigation was to systematically examine the variability associated
with temporally-oriented invertebrate data collected by citizen scientists and consider the
value of such data for use in stream management. Variability in invertebrate data was estimated
for three sources of variation: sampling, within-reach spatial and long-term temporal.
Long-term temporal data were also evaluated using ordinations and an Index of Biotic Integrity
(IBI). Through two separate investigations over an 11-year study period, participants collected
more than 400 within-reach samples during 44 sampling events at three streams in
the western United States. Within-reach invertebrate abundance coefficient of variation
(CV) ranged from 0.44–0.50 with approximately 62% of the observed variation strictly due
to sampling. Long-term temporal CV ranged from 0.31–0.36 with 27–30% of the observed
variation in invertebrate abundance related to climate conditions (El Niño strength) and
sampling year. Ordinations showed that citizen-generated assemblage data could reliably
detect differences between study streams and seasons. IBI scores were significantly different
between streams but not seasons. The findings of this study suggest that citizen data
would likely detect a change in mean invertebrate density greater than 50% and would also
be useful for monitoring changes in assemblage. The information presented here will help
stream managers interpret and evaluate changes to the stream invertebrate community
detected by citizen-based programs.