Reef Fish Associations with Natural and Artificial Structures in the Florida Keys

Abstract

Throughout the Caribbean, coral reefs are transitioning from rugose, coral-dominated communities to flat, soft coral-dominated habitats, triggering declines in biodiversity. To help mitigate these losses, artificial structures have been used to re-create substrate complexity and support reef inhabitants. This study used natural and artificial structures to investigate the factors influencing the use of habitat by reef fish. During 2018 and 2019, divers added artificial structures and monitored the fish assemblages associating with both the artificial structures and naturally occurring corals. Overall, there were more fish on natural structures than on artificial structures. While structure shape did not influence fish use, there was a non-significant trend for increased use of larger structures. Fish observations did not differ across a gradient of shallow, complex reefs to deeper, flatter reefs; however, analyses of feeding guilds revealed clearer patterns: herbivores and omnivores were positively associated with low rugosity reefs where macroalgal abundance was higher, whereas invertivores preferred more rugose reefs. These results suggest that as reefs lose structural complexity, fish communities may become dominated by herbivores and omnivores. It also appears that the addition of artificial structures of the type used here may not mitigate the effects of structure loss on reef fish assemblages.

Examining the ecological function of structure: species assemblages at casitas and coral heads in the Lower Florida Keys

“…Studies have shown that although artificial reefs can harbor high fish densities, their species composition is often distinctly different from that of natural reefs (Fowler & Booth 2012, Burt et al 2013, Simon et al 2013, Mills et al 2017, Komyakova et al 2019. Even studies within different regions of the Florida Keys (Noonan et al 2021) have diverging results regarding the impact of artificial structure on fish communities. The ability of casitas and artificial reefs to restore lost ecological roles is also called into question by the attraction vs. production debate (Bohnsack 1989, Pickering & Whitmarsh 1997, Briones-Fourzán et al 2007, Gutzler et al 2015.…”

Abundance, patterns, and taxa associations of anthropogenic marine debris on reefs in the middle Florida Keys

“…Reefs were censused on SCUBA using a 50 m transect line that ran parallel to the primary axis of the reef and four 30 m transects that laid perpendicular crossing at distances of 10, 20, 30, and 40 m, creating a 50 m × 30 m grid (Noonan and Childress, 2020;Noonan et al, 2021). Rugosity was measured using a chain and tape method (Risk, 1972;Luckhurst and Luckhurst, 1978;Noonan et al, 2021) taking three measurements on each of the four perpendicular transects. Rugosity measurements (n = 12) were averaged for the overall rugosity of each reef.…”