An Invasive Fish and the Time-Lagged Spread of Its Parasite across the Hawaiian Archipelago

Michelle R Gaither,Greta Aeby,Matthias Vignon,Robert J Toonen,Chelsea L Wood,Mark Rigby,Brian W Bowen,Yu-Ichiro Meguro,Christina Runyon,Sebastian C A Ferse

doi:10.1371/journal.pone.0056940

Abstract

Efforts to limit the impact of invasive species are frustrated by the cryptogenic status of a large proportion of those species. Half a century ago, the state of Hawai'i introduced the Bluestripe Snapper, Lutjanus kasmira, to O'ahu for fisheries enhancement. Today, this species shares an intestinal nematode parasite, Spirocamallanus istiblenni, with native Hawaiian fishes, raising the possibility that the introduced fish carried a parasite that has since spread to naïve local hosts. Here, we employ a multidisciplinary approach, combining molecular, historical, and ecological data to confirm the alien status of S. istiblenni in Hawai'i. Using molecular sequence data we show that S. istiblenni from Hawai'i are genetically affiliated with source populations in French Polynesia, and not parasites at a geographically intermediate location in the Line Islands. S. istiblenni from Hawai'i are a genetic subset of the more diverse source populations, indicating a bottleneck at introduction. Ecological surveys indicate that the parasite has found suitable intermediate hosts in Hawai'i, which are required for the completion of its life cycle, and that the parasite is twice as prevalent in Hawaiian Bluestripe Snappers as in source populations. While the introduced snapper has spread across the entire 2600 km archipelago to Kure Atoll, the introduced parasite has spread only half that distance. However, the parasite faces no apparent impediments to invading the entire archipelago, with unknown implications for naïve indigenous Hawaiian fishes and the protected Papahānaumokuākea Marine National Monument.

Highlights

The rate of species introductions has increased dramatically in modern times, correlating with human population growth, advances in transportation, and increased international trade [1], [2]
A subset of the S. istiblenni collected by Vignon et al [18] from L. kasmira in French Polynesia, as well as specimens collected during a field expedition to the region in 2010, were used for genetic analyses
34.7% of L. kasmira sampled in French Polynesia were infected (Table 1)

Summary

Introduction

The rate of species introductions has increased dramatically in modern times, correlating with human population growth, advances in transportation, and increased international trade [1], [2]. While most introduced species never become established, those that persist can have serious economic impacts [3], [4], consequences for human health [5], and can pose a significant threat to biodiversity and ecosystem function [6]–[8]. In response to these risks, resource managers and government agencies are dedicated to the identification, control, and eradication of nonindigenous species (NIS) [9]–[11]. Identifying the native range of cryptogenic species is hampered by the paucity of fossil and historical records, and is problematic among parasites and microbes whose taxonomies are poorly resolved relative to those of more prominent plants and animals [14]

Methods

Results

Conclusion