Artificial reefs facilitate tropical fish at their range edge

Abstract

Spatial planning increasingly incorporates theoretical predictions that artificial habitats assist species movement at or beyond range edges, yet evidence for this is uncommon. We conducted surveys of highly mobile fauna (fishes) on artificial habitats (reefs) on the southeastern USA continental shelf to test whether, in comparison to natural reefs, artificial reefs enhance local abundance and biomass of fishes at their poleward range margins. Here, we show that while temperate fishes were more abundant on natural reefs, tropical, and subtropical fishes exhibited higher abundances and biomasses on deep (25–35 m) artificial reefs. Further analyses reveal that this effect depended on feeding guilds because planktivorous and piscivorous but not herbivorous fishes were more abundant on artificial reefs. This is potentially due to heightened prey availability on and structural complexity of artificial reefs. Our findings demonstrate that artificial habitats can facilitate highly mobile species at range edges and suggest these habitats assist poleward species movement.

Artificial habitats host elevated densities of large reef-associated predators

“…The reefs range from 10–33 m deep, and all are open to fishing, including spearfishing, and diving. The area encompassed by the studied reefs is known to host a diversity of fish species, including tropical, subtropical, and temperate fishes [ 19 , 32 ] Aggregations of sand tiger sharks [ 33 ] and other large reef-associated predators, including snapper, grouper, jacks, and mackerel, are also known to occur on these reefs [ 29 , 34 ]).…”

“…Continued introduction of artificial habitats to marine ecosystems globally can have both positive and negative ecological effects [17,18]. Ecological benefits include increasing connectivity among habitats [17] and potentially facilitating movement of species poleward [19], whereas negative impacts of installing artificial habitats include facilitating the spread of invasive species [20], biodiversity degradation [21], and biotic homogenization [22]. It remains debated whether artificial habitats aggregate fish from surrounding natural habitats or produce new fish biomass.…”

Fitting ecological principles of artificial reefs into the ocean planning puzzle

“…Pete was ahead of his times, practicing marine spatial planning before it was an established practice (Foley et al, 2010). Throughout his career, Pete conducted research related to siting and understanding ecological functions of artificial structures, ranging from wind turbines (Taylor et al, 2016;Voss et al, 2013) and hardened shorelines (Gittman et al, 2014(Gittman et al, , 2015 to artificial reefs (Lemoine et al, 2019;Paxton et al, 2017Paxton et al, , 2018Paxton, Newton, et al, 2020;Paxton, Peterson, et al, 2019;Peterson et al, 2003;Powers et al, 2003;Rosemond et al, 2018); so, this manuscript prescribes a path forward for incorporating ecological principles into planning for artificial reefs that is in line with Pete's visions. We thank Pete for his invaluable mentorship.…”

“…A similar pattern has been documented for eastern fiddler rays ( Trygonorrhina fasciata ) in Australia, which displayed high fidelity to artificial reefs and also moved frequently between nearby natural habitats (Keller et al, 2017). More broadly, spatial connectivity provided by artificial reefs compared to natural reefs, especially in areas that may be habitat limited, can facilitate fish at climatic range edges (Paxton, Peterson, et al, 2019) and potentially provide corridors for large predator movement (Paxton, Newton, et al, 2020). In contrast, improved connectivity can create ecological risks by providing “stepping stones” or connectivity corridors that facilitate the spread of invasive species, including macroalgae (Bulleri & Airoldi, 2005) and invertebrates (Dafforn et al, 2012), as well as predatory fish like lionfish ( Pterois miles and Pterois volitans ) (Morris & Akins, 2009).…”

Wake Region Estimates of Artificial Reefs in Vietnam: Effects of Tropical Seawater Temperatures and Seasonal Water Flow Variation

“…Artificial reefs (ARs) are manmade underwater structures designed to mimic natural reefs for the protection and/or production of marine resources [1][2][3][4]. They have been deployed in various water conditions with specified purposes [5], and accordingly, their roles vary, such as enhancing fishing grounds (e.g., production of biomass [6,7]), conserving marine resources (e.g., anti-trawling and anti-illegal marine mining [2,8]), restoring coral reefs (e.g., seaweed substrates [9,10]), protecting from coastal erosion (e.g., erosion control and dissipation of wave energy [2,11,12]), developing recreational spaces (e.g., diving and surfing sites [13][14][15]), and advancing marine tourism (e.g., sightseeing [16]).…”