DeMartini, E. E., Friedlander, A. M.

Predation, endemism, and related processess structuring shallow reef fish assemblages in the Northwestern Hawaiian Islands

2006

Atoll Research Bulletin

543

237-256

"Data on distribution, abundance, and related patterns, reflecting key ecological processes such as predation, are herein summarized for the shallow-water (< 18-m) reef fishes of the Northwestern Hawaiian Islands (NWHI). This summary is based on the results of two complementary series of relatively recent underwater diver surveys conducted by the Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service, National Oceanic and Atmospheric Administration (NOAA) and alliedagency personnel that began in the early 1990s and extended through 2004. The first series of surveys began in 1992 at French Frigate Shoals and 1993 at Midway Atoll as a re-characterization of a decade-prior baseline assessment conducted by the U.S. Fish and Wildlife Service (USFWS). These surveys were repeated yearly from 1995 through 2000. A second series of assessment surveys began in 2000 and extended through 2001 and 2002. The first series thus is an intensive long-term but spatially limited characterization that complements a spatially extensive but relatively short-term characterization for all ten emergent NWHI reefs in the second series. Among the more important patterns linked to predation and related processes that have been revealed recently are: a nearly threefold greater standing biomass of shallow-water reef fishes in the NWHI (versus the Main Hawaiian Islands, MHI) that primarily reflects the near extirpation of apex predatory reef fishes in the MHI and a large reduction in secondary carnivores; the importance of wave-sheltered habitats as juvenile nurseries for many species and the value of atolls that provide disproportionate amounts of sheltered habitat; the heretofore unquantified extent of endemism (e.g., > 50% by numerical abundance) in NWHI reef fishes and its geographic increase with latitude-longitude to maxima at the three northernmost atolls; and the effects of apex predators on the body size distribution of prey reef fishes and the size-at-sex change in protogynous parrotfishes in the NWHI. These findings have identified the NWHI as one of the few remaining predator-dominated coral-reef ecosystems and an important part of an archipelago with a unique and strongly endemic fish fauna."

FY2004 CRCP Project ID 1086; Project Title: Long-Term Monitoring of Reef Fish, U.S. Pacific Islands; Principal Investigator: Edward DeMartini