Nutritional physiology of the Santa Ana sucker (Catostomus santaanae): A threatened freshwater fish endemic to Southern California

Abstract

Some of the most disturbed and imperilled habitats (and by extension, the inhabitants found therein) in North America are the freshwaters of southern California. With its arid climate, increasing drought conditions and large human population, there are no naturally occurring freshwater systems in southern California that are not impacted directly by humans (Richmond, Backlin, Galst-Cavalcante, O'Brien, & Fisher, 2018). One of the most discussed and litigated naturally occurring residents of southern California freshwater systems is the Santa Ana sucker (Catostomus santaanae), which is a federally threatened (U.S. Fish and Wldlife Service, 2000) native of the Santa Ana, Los Angeles, San Gabriel and Santa Clara River drainages (Richmond et al., 2018) (Figure 1). Catostomus santaanae is an herbivorous fish (Greenfield et al. 1970; Saiki, Martin, Knowles, & Tennant, 2007), and similar to other suckers (family Catostomidae) and minnows (family Cyprinidae) with sub-terminal mouths (Figure 2), C. santaanae is a benthic grazer, subsisting on periphyton