We will focus our efforts on SCUBA-based surveys, which have been shown to produce more reliable estimates of mussel density and biomass than other alternatives in newly infested lakes (e.g., ponar grabs, sledge dredge surveys; Marsden 1992). For SCUBA surveys, detection rates may depend on the diver as well as environmental conditions (e.g., water clarity and amount of submerged plants). If these factors are unaccounted for, differences in counts resulting from changes in detectability may be incorrectly interpreted as differences in abundance.
What is it like to survey for mussels underwater using SCUBA? Here is a video taken from a survey conducted in 2017:
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We developed a short training video that describes how to implement the:
dependent double-observer survey using belt transects (double-observer belt survey)
dependent double-observer distance survey (double-observer distance survey)
We created a vignette showing how the data collected from the above designs can be analyzed using the open-source statistical software platform, R (R Core Team). The vignette (and associated R package for conducting the analysis) can be accessed via the following link.
Marsden, J.E. 1992. Standard protocols for monitoring and sampling zebra mussels. Biological Notes 138. Illinois Natural History Survey. Champaign, IL. 38 pp.
R Core Team 2019. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/.