Scientists Find Two Pacific Atolls Among the Last Ocean Ecosystems Untouched by People
A 2023 expedition to Bikar and Bokak in the Marshall Islands found large sharks, seabird colonies and possibly two new species, and the area is now a marine sanctuary.
Humans have left their mark on almost every place on Earth, from the deep sea to the highest peaks. A new study says two remote coral atolls in the Pacific may be exceptions. Bikar and Bokak, in the Marshall Islands, are among the most intact ecosystems left in the region and possibly the world, according to the researchers.
The study gives the first full ecological baseline of the new National Marine Sanctuaries of Bikar and Bokak, covering the sky, the land and the deep sea. "Bikar and Bokak are not just treasures for the Marshall Islands but for the entire planet," said lead author Dr. Alan Friedlander, a marine ecologist at the University of Hawai'i who was chief scientist of National Geographic Pristine Seas on the joint expedition. He credited the community of Utirik Atoll, which has traditionally guarded the sites for decades.
The atolls are the northernmost in the Marshall Islands. Bikar lies about 116 kilometers (72 miles) from the nearest inhabited atoll, and Bokak about 385 kilometers (239 miles). In 2023, the team surveyed seabirds, shorebirds, vegetation, turtle nesting, coral reefs and fish using scuba, underwater video, deep-sea cameras and a submarine.
The results were striking. Across both atolls the researchers found 15 seabird colonies that were confirmed or likely to be breeding, along with mature native vegetation, active turtle nesting, high reef-fish biomass and large predators. They recorded at least 266 groups of reef fish, 138 groups of fish living at greater depths and 79 groups of deep-sea fishes, plus 15 groups of open-water predators such as sharks, jacks and wahoo. Fourteen of the observed groups had not been recorded in the Marshall Islands before, and two might be species new to science.
The two atolls also differ. Sea turtle nesting was almost entirely at Bikar, where 132 green sea turtle nest pits were counted. Total reef-fish biomass was higher at Bokak, which has coral-dominated reefs, while Bikar supported more kinds of algae. The study surveyed the sites at one point in time, so it could not say what causes the differences. The authors suggested lagoon size, water exchange, sediment movement, nutrient flows or ecological history as possibilities, and Friedlander noted there is "a bit of a lottery" in which species show up and persist at remote places.
The assessment was meant to inform protection under the Marshall Islands' Reimaanlok vision, a community-led conservation framework whose name means "looking toward the future." Two years after the assessment, about 48,000 square kilometers (18,500 square miles) around the atolls were declared the country's first national marine sanctuary.
The researchers say such places are valuable as yardsticks. "They are among the best ecological reference systems we have to better understand what we have lost elsewhere," Friedlander said. They also argue that monitoring should not stop at shallow reefs and should look at ecosystems in full, from the air to the deep sea, so that future climate-driven change can be tracked. Future work should examine how nutrients and animals move between the atolls and the surrounding ocean.
