Color Morph-Habitat Relations in the Arc-Eye Hawkfish Paracirrhites arcatus (Pisces: Cirrhitidae)

Abstract

The arc-eye hawkfish Paracirrhites arcatus, like other congeners, has multiple color morphs whose relative abundances vary greatly among geographic locations. To gain insight into the environmental factors that potentially influence the morph distributions of this species, we conducted two series of surveys at different spatial scales. One extensive, broad-scale survey of 165 central, south, and western Pacific sites was conducted over a 9-yr period (1985-1993). Another series of sites, located along an exposure gradient on the leeward coast of the Island of Hawaii, was surveyed intensively during 1990-1994. Both surveys revealed that relative abundances of the species' two most common (white-striped, WS; melanistic, MEL) color morphs were independent of microhabitat, body size, or adult sex. MoTph frequencies were, however, generally related to bottom depth. Across Oceania, the WS morph was more common at depths > 10 m over a depth range of 1-27 m. At Hawaii, the WS morph increased in abundance at depths > 8 m over a range of 1-12 m and was relatively common at 1-4 m depths wherever frequently used branching corals (Pocillopora meandrina) were scarce. Patterns of color morph frequencies in P. arcatus may represent trade-offs between intraspecific communication and predation risk that exist at differing coral and fish densities. We also discuss morph distributions more generally relative to patterns observed for other, perhaps analogous polychromatisms in reef fishes.