Johnston Atoll: Reef Fish Hybrid Zone between Hawaii and the Equatorial Pacific

Abstract

Johnston Atoll is isolated in the Central Pacific Ocean (16°45′ N 169°31′ W) about 1287 km (800 miles) southwest of Honolulu, Hawaii and 1440 km (900 miles) north of the equatorial Line Islands, Kiribati. The labrid species, Thalassoma lutescens, has a wide range of distribution in the equatorial Pacific. The related species, Thalassoma duperrey, is endemic to the Hawaiian Islands. The pelagic larvae of both species dispersed to Johnston Atoll, where we found a mix of adult phenotypes representing a range of hybridization events over generations. A hybrid acanthurid was also documented. In addition, the arrival and colonization of two pomacentrid (damselfish) species to the atoll was observed in 1999. These pomacentrid sister-species, Abudefduf abdominalis and A. vaigiensis, have become established populations with subsequent hybridization. The biogeography of the Johnston Atoll coral reef fish population shows some degree of local population retention. It is also evident that this biogeographic isolation is periodically compromised by large ocean current oscillations in the equatorial and central Pacific Ocean that bring larval fishes from either Hawaii or the Line Islands, and may distribute Johnston Atoll originating larvae elsewhere as well. The reef fauna and oceanography of this atoll provides the circumstances for improving scientific insight into marine fish speciation and island biogeography.

Sustaining empire: Conservation by ruination at Kalama Atoll

“…Johnston Atoll has served as a highly productive, safe nesting area over the years because the military presence has kept tourists and leisure sailors away, and prevented the introduction of predators such as cats or rats. (Lobel et al., 2012: 9)The ecological characteristics of such “military landscapes” and the ways in which militaries embrace environmental or conservationist ideas and practices, are discussed under the rubric of “military environmentalism” (see Davis, 2007; Durant, 2007; Havlick, 2018; Kuletz, 2001; Lawrence et al., 2015; Martini, 2015; Sanders, 2009) or “military ecological governmentality” (Kajihiro, 2020: 405).…”

“…Johnston Atoll has served as a highly productive, safe nesting area over the years because the military presence has kept tourists and leisure sailors away, and prevented the introduction of predators such as cats or rats. (Lobel et al., 2012: 9)…”

“…The process of militarization can then employ arguments about habitats and biodiversity (Havlick, 2007). The 2012 ecological assessment of Kalama states that “Today, Johnston Atoll provides an excellent example of how military operations can be compatible with the ecosystem and both can thrive together successfully” (Lobel et al., 2012: 2). Havlick (2007: 153) coined the term “ecological militarization” to describe this discourse of military compatibility with the environment (see also Havlick, 2018; Lawrence et al., 2015).…”

“…In the years following, the Johnston Atoll clinic reported cases of ciguatera poisoning by island residents after eating fishes caught in the lagoon. (Lobel et al., 2012: 31)Here, military terraforming produces toxicity, which leads to new research opportunities involving multiple species. This initial reef fish survey in turn prompted a series of biological surveys by the University of Hawaiʻi from 1963 to 1964 (Lobel et al., 2012: 4).…”

“…Linked to the Hawaiian Islands by ocean currents and winds, Kalama Atoll emerges from the sea 825 miles southwest of Honolulu fringed by shimmering reef (Lobel et al., 2012). 1 The atoll has been the ground beneath several nuclear test disasters, thousands of gallons of leaked Agent Orange, and the incineration of over 2000 tons of nerve agents.…”