Consistent spatial patterns in multiple trophic levels occur around artificial habitats

With increasing global rates of urbanization, it is important to understand the ecological functions of artificial structures. One way to assess the ecological functions of such structures is to test whether they function similarly to natural habitats. In marine systems, naturally occurring structured habitats, such as coral reefs and rocky reefs, support aggregations of planktivorous fish, often inducing spatial patterns in prey and predators. Whether similar spatial patterns occur around submerged artificial structures, which often have more abrupt topographies than natural habitats, remains less well understood. We tested whether consistent spatial patterns in planktivorous fish, their prey (zooplankton), and their predators (piscivorous fish) were present around artificial structures. We first documented spatial distributions of these 3 trophic groups around 15 marine artificial structures (shipwrecks) using acoustic surveys and then asked how spatial distributions of each trophic group relate to the others. We found that the center of planktivorous fish aggregations occurred an average of 39 m from habitat edges. Zooplankton prey were detected throughout nearly 25% of surveyed areas around habitats. Piscivorous fish predators concentrated closest to habitats. Further analyses revealed that these patterns sometimes related to environmental factors, such as water current magnitude and direction. Because spatial distributions of planktivorous fish, their prey, and their predators were consistent across sampled artificial structures, our findings suggest that artificial structures influence spatial patterns across adjacent trophic levels. This finding adds to a growing body of evidence that artificial habitats provide important ecological functions.