Fish colonization on the Ebenezer II, a 25.5m merchant marine vessel, was studied from May 2002 - July 2003. The ship was scuttled in May 2002 off Broward County, Florida at a depth of 21m and was censused 10 times during the study period using a modified Bohnsack and Bannerot visual census method. Adjacent natural reefs and the Mcallister, a nearby, 30m tugboat deployed in June 1998, were censused during the same period.
Distinct changes in the fish assemblage on the Ebenezer II were observed throughout the sample period. A pioneer assemblage was observed during the first three months, characterized by the settlement of juvenile fishes «5 cm). Subsequently, numbers of juveniles decreased either through emigration, predation or growth. Resident species made up 52.5% of the total abundance but transient fish species made up 78% of the total fish biomass during the study period.
Surprisingly, attraction of adult fish from both natural reefs and the Mcallister was not a major factor in assemblage fonnation. The primary adult fishes attracted to the Ebenezer II were herbivores. These fishes steadily increased in abundance throughout the study period, presumably due to increased food availability as benthic algal communities developed. A similar trend of increasing herbivores with increasing soak time was observed on the Spiegel Grove, a 153m vessel-reef sunk off Key Largo in May 2002.
The fish assemblages on the artificial reefs were more similar to each other than to natural reefs. Vessel-reefs had sixty species in common, while the Ebenezer II only had thirty-nine species in common with natural reefs. Several species common to vessel-reefs were absent or rare on nearby natural reefs. This may indicate that vessel-reefs are providing early juvenile and adult habitat that is not available on natural reefs
