Comparisons of turf communities from Pendleton Artificial Reef, Torrey Pines Artificial Reef, and a natural reef using multivariate techniques

The construction of artificial reefs for augmenting fish production and mitigating habitat loss has increased markedly in the United States in the last decade. Despite their widespread use, there is much uncertainty about both the actual benefits of artificial reefs and the ecological mechanisms through which such benefits might be produced. This paper reports on a five and one-half year study of the development of turf communities on a new artificial reef in southern California, Pendleton Artificial Reef (PAR). These communities were sampled extensively and compared to analogous communities at an older artificial reef and a natural reef in the region. Sampling was designed to document potential differences due to time since construction, height above the ocean bottom, season, location within reef (e.g., current and edge effects), and sporadic disturbances. Questions about the speed and pattern of development of turf communities are important because of their role in providing habitat and food for both resident and transient fish populations. Multivariate analyses, which are more sensitive than species-by-species approaches, were used to describe and compare temporal and spatial patterns. These analyses showed a typical successional pattern at PAR in which the turf community became progressively more similar to that at older reefs over time. At PAR, species groups dominated by a mud ectoproct, barnacles, algal turf, hydroids, erect ectoprocts and Rhodymenia spp. were steadily replaced by species groups characterized by the scaled worm mollusk, the ornate jewel box, and gorgonians over the period of the study. The nature and speed of this process suggests that it may take 10–15 yrs for turf communities on new artificial reefs to mimic those on natural reefs.