Microhabitat Characteristics and Management of the Trinity Bristle Snail in the Greater Trinity Basin of Northern California

Abstract

Microhabitat assessment of the Trinity bristle snail (Monadenia setosa), a state threatened species, was conducted at 88 randomly selected sites throughout its known geographic range in northern California. Nineteen abiotic and biotic environmental variables were measured for each site. Results of univariate and multivariate analyses indicate that sample sites were dominated by physical parameters of air and soil temperature, and elevation and exposure in association with habitat structure consisting of the presence, size, and nearness of large woody debris, rocky surface and subsurface structure, and riparian stream corridors, respectively. No individual or small suite of attributes defined microhabitat suitability for the species based on site-specific characteristics. Instead, a robust combination of physical and biological variables was key to the distribution of specimens at the population-level, most of which were allied with structural elements of the sample site.