Successional Development of the Turf Community on a Quarry Rock Artificial Reef

Pendleton Artificial Reef (PAR) was constructed to investigate the potential of quarry rock artificial reefs as compensation for damage to nearshore habitats. A long-term study of the successional development of the turf community (sessile invertebrates and understory algae) on PAR began 1 year after reef construction. This epibenthic assemblage plays an important role in the overall community structure of reefs. Surveys of the turf community were conducted on PAR from fall 1981 through fall 1986. To determine if PAR was developing a turf community characteristic of more mature reefs, the study was expanded in fall 1984 to include sampling of two reference reefs—Torrey Pines Artificial Reef (TPAR) and Las Pulgas Reef (LPR). Percent cover of turf community organisms was estimated using randomly placed 0.125 m² quadrats. Species encountered were grouped into 24 broad taxa. During the 5-year study, the turf community on PAR became progressively more complex; it evolved from a few pioneer taxa into a diverse community. Development occurred in three “phases”: (1) Early PAR—dominated by the mud ectoproct (Cryptoarachnidium argilla), (2) Middle PAR—dominated primarily by algal turf, and (3) Late PAR—dominated by erect ectoprocts. Comparisons between PAR and the reference reefs revealed that the assemblage of taxa on PAR in fall 1986 was similar to those on TPAR and LPR. However, abundances of several major components were lower on PAR. Although these differences should decrease with time as development continues on PAR, there will always be some inherent variation caused by differences in reef location and design.