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Probabilities of detecting submersed aquatic vegetation species using a rake method may vary with biomass

March 9, 2021

Levels of submersed aquatic vegetation (SAV) are commonly assessed using a modified garden rake. However, the utility of the rake sampling method relative to methods that are typically viewed as more definitive (and expensive) such as snorkeling and coring remains a matter of debate. This study explores whether probabilities of species detections for four SAV species varied among sampling units in a rake-biomass study and, if so, whether such variation reflected variation in species abundance. Variation in detection probabilities, when unaddressed, may yield biased estimators of percent frequency of occurrence (“occupancy”) and of occurrence-habitat associations. Biomass-driven variation in detection probabilities is important because such variation may not be explainable using covariates typically measured when sampling using the rake method. This study found substantial among-unit variation in detection probabilities, with majorities of that variation on the logit or modeling scale being associated with biomass but not with the non-biomass covariates substrate type, water depth and day of study. The study closes by exploring sampling protocols and modeling methods that may yield improved SAV occupancy estimates.

Citation Information

Publication Year 2021
Title Probabilities of detecting submersed aquatic vegetation species using a rake method may vary with biomass
DOI 10.1016/j.aquabot.2021.103375
Authors Brian R. Gray
Publication Type Article
Publication Subtype Journal Article
Series Title Aquatic Botany
Series Number
Index ID 70220157
Record Source USGS Publications Warehouse
USGS Organization Upper Midwest Environmental Sciences Center