SEASON, SUBSTRATE ORIENTATION, AND DEPTH AFFECT NATIVE AND NON-INDIGENOUS SPECIES SETTLEMENT AND SUCCESSION ON ARTIFICIAL REEFS

To mitigate negative impacts from anthropogenic activities, resource managers are implementing multi-function projects such as artificial reefs to protect infrastructure while restoring native biodiversity. Artificial reefs can provide habitat for a wide array of fish and invertebrates, but the risk of favoring non-indigenous species motivates investigating whether season of deployment, depth, and habitat orientation could be manipulated to favor native communities. To test whether these factors yield distinct community compositions by impacting the priority settlement and successional sequence of recruiting invertebrates and macroalgae, replicate (n = 6) recruitment tile sets were deployed via SCUBA on a new artificial reef (designated as FeISH - Fish, eelgrass, Subtidal, Intertidal Habitat) in San Diego Bay, CA, USA across 4 seasons and three depths (-5, -10, and -20ft. MLLW). Replicates were removed at 3-, 6-, and 12-months post deployment, and percent cover and density of identified species, species richness, and community composition were recorded. Significantly different communities across all deployment periods were driven by an interaction of season and depth, indicating these factors can drive early community structure on artificial reefs. Despite differences in community composition persisting after one year, nMDS trajectory plots revealed community convergence over time. Percent cover and abundance of key species such as native Ostrea lurida and invasive Sargassum spp. varied across season, depth, and tile orientation. These factors can be manipulated to achieve particular outcomes if resource managers are targeting species of concern. However, community convergence over longer time periods may dilute the importance of this recommendation as other yet-unidentified factors exert their influence