Artificial Marine Reefs off Catalina Island: Recruitment, Habitat Specificity and Population Dynamics

Seven identical artificial reefs were constructed and maintained at a depth of 10m on a sand flat near heavily populated kelp beds immediately offshore from Catalina Island, California. The reefs were of steel reinforced concrete and, in addition to vertical and horizontal substrates, each offered as habitat 144 cylindrical interstices of four diameters in specific geometric array (Zahary and Hartman, 1983). Three reefs were subjected to a pulsed disturbance by monthly removal of macro-algae, while the remaining four were not disturbed. Time series data were collected on density, diversity, species composition and temporal stability of both plant and animal inhabitants. The data composed over 30,000 individual organisms identified to various taxonomic levels and an additional 35,000 interstitial census points for fishes and invertebrates. This paper describes habitat specificity studies of the two most common resident fishes on the reefs: Chromis punctipinnis (the blacksmith) and Lythrypnus dalli (the bluebanded goby). We also show that, in opposition to previous opinion, a significant portion of the C. punctipinnis population shelters in the open even when interstitial space of appropriate size is available.