Effects of Three Substrate Variables on Two Artificial Reef Fish Communities

Effects of substrate rugosity, percent substrate cover, and vertical reflief on resident and semiresident ichthyofaunal communities associated with two sunken barges were investigated off Panama City, Florida.

Measures of substrate rugosity and percentage substrate cover indicate Offshore Barge had 1.75 times the amount of surface area accessible to reef organisms for both sand and metal substrates compared to that available at Inshore Barge. Offshore Barge also supported a significantly greater abundance and species richness of resident fishes during summer (≥ 21°C) and winter (≤ 18°C) censuses. Both barges supported similar dominant species with no significant differences detected in the evenness of fish abundances. Midwater structures on Inshore Barge supported significantly greater numbers of semiresident species during summer censuses. However, greater abundance of semiresident species on Offshore Barge during winter indicated that higher structural complexities take precedence over vertical relief in attracting or concentrating these fishes when abundances (or temperatures) drop below a critical level.