Visual cues from an underwater illusion increase relative abundance of highly reef-associated fish on an artificial reef

Cues from visual, auditory and olfactory stimuli affect habitat selection by reef fish, yet questions remain regarding how fish use visual cues to select habitats. With growing numbers of human-made structures, such as artificial reefs, deployed on ocean floors, understanding how visual cues influence fish selection of human-made habitats is timely. We conducted a field experiment to test whether visual stimuli influenced the relative abundance of fish on an artificial reef. We discovered that visual cues from an illusion created by a mirror installed on the reef increased the relative abundance of highly reef-associated fish. Specifically, when exposed to the mirror, numbers of highly reef-associated fish increased 35% relative to an experimental control treatment with a transparent added structure and 54% relative to a full control without an added structure. These results demonstrate that visual cues, such as illusions of additional habitat and more fish, can entice more highly reef-associated fish to use artificial reefs and play a more substantial role in habitat selection than the effects of added physical structures alone. As numbers of human-made marine structures continue to increase, simple augmentations enhancing visual evidence of available habitat structure or relative fish abundance may serve to increase the local abundance of fish.

Duke Scholars

Author Avery Paxton Marine Science and Conservation