Volunteer biological monitoring: Can it accurately assess the ecological condition of streams?

Abstract

Government agencies have begun to use biological monitoring data collected by volunteers for official purposes, but questions have been raised regarding the validity of conclusions about ecological condition. We conducted a 2-yr study that assessed, modified, and validated the Virginia Save-Our-Streams (SOS) program, a popular volunteer monitoring program that emphasizes benthic macroinvertebrates. The study design consisted of sampling sites using accepted professional methods concurrently with volunteers using the SOS protocol. In addition, sites previously sampled by volunteers were re-sampled using professional methods. The numerical results from volunteer and professional samples were not correlated (r = 0.46) and at times produced different conclusions about ecological condition (65% agreement). The Virginia SOS protocol consistently overrated ecological condition. We determined that the reason for the inaccuracy was the simplistic numerical analysis in the volunteer protocol, which was based solely on presence of taxa. We developed a quantitative multimetric index that was appropriate for use by volunteers, and the SOS sampling protocol was modified to obtain counts of macroinvertebrates in the various taxa. The modified SOS protocol was then evaluated with a different set of concurrent samples taken by volunteers and professionals. The modified SOS protocol proved feasible for volunteers, and the new multimetric index correlated well with a professional multimetric index (r = 0.6923). The conclusions about ecological condition reached by the volunteer and professional protocols agreed very closely (96%). This study demonstrated that volunteer biological monitoring programs can provide reliable information about ecological condition, but every protocol needs to be validated by standard quantitative methods.