Palmyra Atoll

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Overview

Palmyra Atoll is one of the few places where scientists can study an intact, unfished coral-reef ecosystem. The U.S. National Fish and Wildlife Refuge (5.8885° N, 162.0787° W) is 1600 km south of Hawai’i and has never supported permanent human habitation or the commercial or subsistence fisheries associated with it. Compared to inhabited atolls in the Northern Line Islands chain, marine systems in Palmyra support high apex-predator biomass (DeMartini et al., 2008; Sandin et al., 2008) and diverse parasite assemblages. The remarkable marine life at Palmyra Atoll lives in four primary marine habitats: submerged reef, intertidal reef (back reef), intertidal sand flats and deep-water lagoon.

We wondered whether environmental DNA might be a cost-effective way to assess fish communities on Palmyra Atoll, a remote coral atoll that is under large-scale and long-term ecological restoration to repair damages done in WWII when the area was a military base. 

In August 2017, we took water samples from 22 sites. Depth and tide direction were noted for the intertidal sites. We sampled five sites on submerged reef (two on the fore reef, and three on the inner reef), one sample in the deep-water lagoon, and 16 sites on the intertidal sand flats. We sampled all 16 flat sites on outgoing tides and seven of these sites again on incoming tides.

We found fish DNA in water samples, confirmed that common fish contributed more eDNA, found a habitat signal, and confirmed that tidal variation had little detectable effect.