Widespread Dispersal of the Crown-of-Thorns Sea Star,Acanthaster planci, across the Hawaiian Archipelago and Johnston Atoll

Molly A Timmers,Chris E Bird,Robert J Toonen,Kimberly R Andrews,Russell E Brainard,Marta J Demaintenton

doi:10.1155/2011/934269

Abstract

The population structure of marine species is variable along the Hawaiian Archipelago; thus, it is important to understand dispersal and recruitment patterns for economically and ecologically important taxa to inform Ecosystem-based Management. Connectivity of the coral-eating crown-of-thorns sea star,Acanthaster planci, was examined from Johnston Atoll and 12 locations across the Hawaiian Archipelago. Sequences of mitochondrial DNA from 383 individuals were analyzed to infer patterns of gene flow among the Northwestern Hawaiian Islands (NWHIs), the main Hawaiian Islands, and Johnston Atoll. Population samples were genetically similar across the Hawaiian Archipelago with the exception of the west side of the Big Island of Hawaii, which was significantly differentiated from the majority of Hawaiian samples (pairwise , ). Although differentiated, Hawai`i West shares haplotypes with every other site across the Hawaiian Archipelago. Johnston Atoll was genetically distinct from every location (pairwise , ) except French Frigate Shoals (, ), supporting connectivity between the central NWHIs and Johnston Atoll. Taken together with the lack of geographic population structure and haplotypes shared among all populations, these results indicate widespread larval dispersal with few restrictions to gene flow along the archipelago.

Highlights

The most geographically isolated island group in the world, the Hawaiian Archipelago, spans 2500 km and is composed of eighteen primary islands, reefs, and atolls separated into the remote Northwestern Hawaiian Islands (NWHIs) and the inhabited main Hawaiian Islands (MHIs)
Some genetic structuring was found between Hawai‘i West and the rest of the Hawaiian Archipelago, the absence of A. planci genetic population structure along 2500 km of the Hawaiian Archipelago indicates that the dispersal potential of this coral-eating sea star is vast
High dispersal is generally associated with a lack of genetic population structure [80, 81]

Summary

Introduction

The most geographically isolated island group in the world, the Hawaiian Archipelago, spans 2500 km and is composed of eighteen primary islands, reefs, and atolls separated into the remote Northwestern Hawaiian Islands (NWHIs) and the inhabited main Hawaiian Islands (MHIs). The NWHIs and MHIs are distinguishable by human habitation, geomorphology, and geological age; the MHIs are heavily populated high islands and geologically young, while the NWHIs are geologically older and predominantly uninhabitable low coral islands and atolls. Fish communities and biomass in the NWHIs are unparalleled to the MHIs [7], and in terms of ranking overall “health”, the NWHIs have retained their biological richness and value compared to the MHIs [9,10,11]. Under protection as the Papahanaumokuakea Marine National Monument, the NWHIs remain shielded from most direct threats induced by human activities such as commercial fishing, military use, and tourism [11]. To inform ecosystem-based management in both the Monument and the reefs in the MHIs, it is necessary to know the direction and magnitude of connectivity across

Methods

Results

Discussion

Conclusion