Community structure and energy flow within rhodolith habitats at Santa Catalina Island, CA

The purpose of this study was to describe the floral and faunal community associated with rhodolith beds, which are aggregations of free-living coralline algal nodules, off of Santa Catalina Island. Surveys of macroalgal cover, infaunal and epifaunal invertebrates, and fishes suggest rhodolith beds off Santa Catalina Island support greater floral and faunal abundances than adjacent sand habitat. Community separation between rhodolith and sand habitats was due to increased presence of fleshy macroalgae, herbivorous gastropods, and greater abundance of infaunal invertebrates dominated by amphipods, mainly tanaids and gammarids. Stable isotopes were used to determine important sources of primary production supporting rhodolith beds and to identify the major pathways of energy. Stable isotopes suggest the rhodolith bed food web is detrital based with contributions from water column particulate organic matter, drift kelp tissue, and kelp particulates from adjacent kelp beds.