Plate Nº 43 · recorded November 12, 2026
Biology & EvolutionReported finding
Two Remote Pacific Atolls Rank Among the World's Last Intact Reefs
Bikar and Bokak atolls in the Marshall Islands hold some of the world's most intact ocean ecosystems, a new Frontiers in Marine Science study finds, including 14 first records and possibly two new species.
By Marcus Bennett4 min read739 words
In brief
- A 2023 expedition surveyed Bikar and Bokak atolls, leading to a ~48,000 sq km national marine sanctuary declared two years later.
- Researchers recorded 15 seabird colonies, at least 266 reef fish groups, and 132 green sea turtle nest pits.
- Fourteen observed groups had never been recorded in the Marshall Islands; two may be new to science.
- Bikar and Bokak lie 116 and 385 km from the nearest inhabited atoll, limiting human impact.
- The study was published in Frontiers in Marine Science, DOI 10.3389/fmars.2026.1957660.
Two coral atolls in the Marshall Islands — Bikar and Bokak — host some of the most intact ecosystems left in the Pacific, and possibly on the planet, according to a new study published in Frontiers in Marine Science. Roughly 48,000 square kilometers (18,500 square miles) of ocean around them became the country's first national marine sanctuary in 2025, two years after the research team completed its assessment.
What did the researchers actually find?
In 2023, a joint expedition surveyed the atolls from sky to deep sea. The team counted seabird and shorebird populations, mapped vegetation, documented turtle nesting, and surveyed coral reefs and fish communities using scuba dives, underwater video, deep-sea camera deployments and a submarine.
The results were striking. Across both atolls, the researchers confirmed or flagged as likely breeding 15 seabird colonies. They recorded at least 266 groups of reef fish, 138 groups of fish living at greater depths, and 79 groups of deep-sea fishes. Fifteen groups of open-water predators — including sharks, jacks and wahoo — appeared in the counts.
Fourteen of the observed groups had never been recorded in the Marshall Islands before. Two more may be species entirely new to science, though that remains unconfirmed.
"These atolls have extensive seabird colonies, mature native vegetation, active turtle nesting, high reef-fish biomass and large predators, coral-dominated reefs at Bokak, structurally complex mesophotic habitats, and surprisingly diverse and poorly known deep-sea communities," said first author Dr. Alan Friedlander, a marine ecologist at the University of Hawai'i and chief scientist for Pristine Seas on the expedition.
How do the two atolls differ?
Despite sharing many species, Bikar and Bokak diverge in structure. Sea turtle nesting concentrated almost exclusively at Bikar, where the team recorded 132 green sea turtle nest pits. Bokak, with its coral-dominated reef communities, held the higher total biomass of reef fish. Bikar, in turn, supported more types of algae.
The study, which surveyed the atolls at a single point in time, could not determine what drives these differences. Possible causes include lagoon size, water exchange, sediment transport, habitat configuration, nutrient dynamics or ecological history.
"There is also a bit of a lottery involved as to which species show up and persist at remote locations," Friedlander added.
The remoteness itself is measurable. Bikar and Bokak are the northernmost atolls in the Marshall Islands, lying approximately 116 and 385 kilometers (72 and 239 miles) respectively from the nearest inhabited atoll.
Why does a baseline matter?
For practitioners, the value lies in reference data. These ecosystems function with minimal human influence, which makes them rare benchmarks.
"They are among the best ecological reference systems we have to better understand what we have lost elsewhere and to provide fundamental insights needed for effective conservation and restoration efforts," Friedlander said.
The researchers draw two practical lessons for future monitoring. First, surveys should not focus exclusively on shallow reefs; assessing ecosystems in their full complexity gives a stronger foundation for conserving integrity and tracking climate-driven change. Second, future work should examine nutrient transfer and ecological connectivity between habitats — something this expedition did not do.
The study also credits local stewardship. The community of Utirik Atoll has traditionally and vigilantly safeguarded these ecosystems for decades. "Bikar and Bokak are not just treasures for the Marshall Islands but for the entire planet, a gift from the community of Utirik Atoll," Friedlander said.
What comes next?
The survey fed directly into policy. "We set out to inform the creation of a highly protected area within the scope of the Marshall Islands' Reimaanlok vision, which means 'looking toward the future,'" Friedlander explained. Reimaanlok is a national, community-led conservation framework designed to protect marine and terrestrial resources while ensuring island life thrives for generations.
"The Marshall Islands government should be applauded for its foresight in protecting these global biodiversity hotspots, where human activity is distant and habitats teem with life," Friedlander concluded. "Large marine protected areas serve as globally important ecological reference systems for understanding the structure and future trajectories of tropical oceanic ecosystems in the Anthropocene."
The full study — Alan M. Friedlander et al., From the sky to the deep sea: ecosystem structure and ecological integrity across the National Marine Sanctuaries of Bikar and Bokak, Marshall Islands — appears in Frontiers in Marine Science (DOI: 10.3389/fmars.2026.1957660). As a single-time snapshot, its findings should be read as a baseline, not a trend.
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News editor covering regulation, policy and their impact on general science news at SciBeat.
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