Abstract

It is well known that nearshore reefs provide habitat for a diverse array of fishes and macro-invertebrates, but there are few studies that compare nearshore artificial and natural reefs and explore the temporal variations in their communities. The primary objective of this study was to quantify seasonal patterns of fish and macro-invertebrate associations with several natural and artificial reef types in the northeastern Gulf of Mexico. The study area off the coast of northwest Florida was divided into 4 blocks, each containing both natural and artificial reefs (Figure 1). Natural reefs were composed of two types: (1) exposed rocks covered with macro-invertebrates, “rocky reefs”, and (2) macro-invertebrates without exposed rock, “invertebrate only reefs”. Artificial reefs consisted of several types of materials: concrete debris, concrete culverts, reef-balls, concrete beams, and a steel-hull shipwreck (Table 1). The exact position of reef types was determined by mapping a 1-km x 1-km area around known reef structures (Figure 1) using a Humminbird side-imaging sonar system and methodology described in Kingon (2013). Within each block, five sampling stations were randomly selected from the maps to represent each of the three reef types. Thus, there were 15 sampling stations per block, except in blocks 2 and 4 where additional stations were added to include the different artificial reef structures present (Table 1). Stations were surveyed seasonally using Submersible Rotating Video systems (SRVs, Koenig and Stallings 2015) to assess fish diversity and abundance as well as habitat characteristics. Coverage of sessile macro-invertebrates and algae was quantified seasonally from down-looking quadrat photos taken along three random 30-m transects within each reef type of each block. The study was run for two years, from summer 2012 to summer 2014.

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