Palmyra National Wildlife Refuge Ecology

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Palmyra Atoll is a low-lying coral atoll and National Wildlife Refuge located south/southwest of Hawaii near the equator in the central Pacific Ocean. USGS is a member of the Palmyra Atoll Research Consortium, which fosters collaborative multi- and inter-disciplinary studies by U.S. Department of the Interior agencies (USGS and U.S. Fish and Wildlife Service), academic institutions, and non-governmental organizations on the terrestrial and marine ecosystems at Palmyra Atoll. Dr. Kevin Lafferty and colleagues are using Palmyra Atoll as a natural laboratory for studying an intact coral reef ecosystem.

The U.S. Fish and Wildlife Service’s National Wildlife Refuge has several management challenges on Palmyra Atoll that USGS WERC helps study, including assessing the consequences of rat removal on terrestrial food webs, understanding ecological complexity of intact coral reef systems, and monitoring species of special interest like sharks. 

 

Food Web for the Intertidal Sand Flats

Dr. Kevin Lafferty co-supervises Ph.D. student John McLaughlin, who leads ongoing field work to determine the abundance and size-frequency distributions of invertebrates, fishes, and birds in Palmyra Atoll’s sand flats. Sand flats are one of the atoll’s largest habitat types and offer important habitat for bonefish, reef sharks and shorebirds. This project will enhance scientists’ understanding of Palmyra’s wildlife and identify resources (habitat types, food sources, etc.) required by species of interest like the bristle-thighed curlew. Further goals include establishing a baseline for resources likely to be impacted by proposed lagoon restoration projects, which could reduce the atoll’s sand flat habitat. Knowing what species use these areas is important for understanding their value to the ecosystem, identifying areas with high biodiversity and the best locations for restoration. The project will initiate the process of establishing ecological networks for all habitats at Palmyra Atoll (these are a fundamental tool for ecosystem-based management).

 

Monitoring Palmyra's Recovery after the Removal of Invasive Rats

Rat climbing tree at Palmyra Atoll
Photo of an invasive rat climbing a tree on Palmyra Atoll, a tropical reef island in the Pacific.(Credit: Graham Carroll. Public domain.)

Before their removal, non-native rats destroyed important habitat and threatened the survival of nesting seabird species, migratory shorebirds, and crabs on Palmyra Atoll. The U.S. Fish and Wildlife, Nature Conservancy, and Island Conservation launched a collaborative effort to remove the rats and allow the local ecosystem to recover. Dr. Kevin Lafferty assists these agencies in monitoring the response of different members of the ecosystem, from seabirds to trees.

 

Monitoring Sharks at Palmyra Atoll

In order to respond to lease requests for floating offshore wind projects, the U.S. Bureau of Ocean Energy Management (BOEM) needs data on species and habitats that could be affected by offshore energy at Palmyra National Wildlife Refuge. Human activities have the potential to influence the health and abundance of important wildlife species, including the ocean’s top predators: sharks. Although these powerful animals have suffered global declines because they grow slowly, are slow to reproduce, and easy to overfish, they are abundant at Palmyra Atoll.

Dr. Kevin Lafferty is testing several methods of estimating shark numbers at Palmyra to support BOEM in siting offshore wind energy projects. One strategy involves studying the link between Palmyra’s ecosystem health and its biodiversity. A healthy marine environment, like that at Palmyra, will have more diverse species of all kinds, from tiny parasites to top predators. Dr. Lafferty is testing the potential for using the presence of parasites to indicate shark abundance. Another tactic involves using shark scales (denticles) as shark indicators. Denticles are well-preserved in fossil reef sediments, are shed in large amounts, and can provide insight into the local history of sharks.

BOEM has also expressed interest in using Palmyra Atoll as a reference site for activities in the Pacific. To this end, Dr. Lafferty collaborates with BOEM Scientists to understand the relevance of sea bird, shorebird, shark, fish and coral monitoring to BOEM’s mission. 

 

Sooty Terns Nest and Chicks Video

Gray Shark at Palmyra Atoll Video

Manta Ray Fly-by Video

Palmyra Reef Tropical Fish Video