Chasing ghosts in the middle of the Pacific Ocean

Marine biologist Randi Rotjan studies specimens, dead or alive, in protected areas to learn more about reef recovery

By Randi Rotjan | Boston University

A robotic arm lifts a piece of coral from the ocean floor.

As Halloween approaches, consider this spooky environment: Alone, on the bottom of the ocean. 1,646 meters below the surface under bone-crushing pressure. Where the light never shines. Where distant sounds echo hauntingly. Where it’s a frigid 2.6 degrees Celsius. In the most remote part of the Pacific Ocean, so far-flung that the nearest humans (outside your cohort) are the ones on the space station.

Fear not: I’m on the surface, surrounded by colleagues. But the robot I’m controlling currently calls the setting I just described its home. It’s an unmanned, undersea rover, and it’s navigating seamounts that have never been seen prior to today, let alone mapped. My colleagues and I are navigating this bot for the sake of science, and for our coral reefs.

We spent last night using our ship’s high-tech multi-beam systems to generate a 5-meter gridded high definition bathymetric map to choose a dive site, and then lower a new, custom-built submersible: a remotely-operated vehicle (ROV) named SuBastian, owned and operated by the Schmidt Ocean Institute.

The SuBastian.

Fast forward an hour later, and here we are — with a map and a robot — rapidly acquiring 4K images of deep sea creatures that have never been seen, in a place that has never been explored, using technology that is newly invented. I’m working with a diverse team of scientists and engineers to sample corals and other marine invertebrates using a variety of techniques: suction sampling, coral cutters, and some new soft robotics technology — “squishy fingers” and “linguini fingers” (developed by the Wyss Institute at Harvard) — to sample delicate and gelatinous targets.

The robotic arm of the SuBastian can grab specimens for study.

We’re using this incredible technology to look at this incredible biology, and we’re doing it in a special place that I have been privileged to work on and with for almost a decade: the Phoenix Islands Protected Area (PIPA), where I am the Chief Scientist. PIPA is owned by the Republic of Kiribati, and I have had the honor of supporting this country by helping to design and advance the scientific research program for its entirety: a California-sized, uninhabited, marine-protected area.

So. Those ghosts I mentioned.

We are diving on ancient volcanoes, 50–80 million years old, that are haunted with history. There are some corals that are estimated to be thousands of years old, still alive, still thriving. But, there are also some that have died, evident now only from their rubble, or their ancient calcareous bases and stalks still standing as a sort of tombstone marking the grave of a deep sea marine invertebrate that once was. There are iron-manganese crusts, a sign of slow and steady precipitation of minerals over time, accumulating over basaltic substrates, blanketing the former volcano. And finally, there are the living invertebrates — so many of which are clear and ghost-like (transparent or translucent), with pale or shimmery coloration — just quietly sitting on the lightless seafloor, eating marine snow as it gently falls from the surface.

“There are also some that have died, evident now only from their rubble, or their ancient calcareous bases and stalks still standing as a sort of tombstone marking the grave of a deep sea marine invertebrate that once was.”

I am here to document, collect, and study these organisms. I am helping establish a baseline inventory of deep sea creatures for PIPA, and studying the species-specific interactions between corals, their predators, and their microbes (in collaboration with Anna Gauthier and the Kagan Lab at Harvard, the Shank Lab at Woods Hole Oceanographic Institution, and the Cordes Lab at Temple University). Together, we are examining the ecology, morphology, histology, genetics, and microbial ecology of these organisms and communities to help support conservation science in this fully protected area.

The Falkor ship that Rotjan calls home during her journeys around PIPA.

Along the way, we’ve been tricked and treated. The tricks? Some elusive samples have literally fallen between our robot fingers, denying science the opportunity to study them. Some haloed corners of our screens have whispered excitement, but then turned out to reveal only shadows or oddly-shaped rocks. The treats? New discoveries, almost by the hour. Fair weather. Calm seas. A collaborative and energized ship with 42 people working towards this common goal of discovery, science, and engineering. The joy of narrating our dives live to our friends and family back home, and an anonymous audience of over 600,000 viewers who are tuning in to see these incredible habitats with us.

Ghosts are ghouls may be out there, but I’m more interested in the magic that science has to offer. Through careful thinking, hypothesis-testing, engineering, natural history and curiosity… I don’t need a costume or a mask this Halloween. I’m a scientist, and this is as real as it gets.

The team on the Falkor.

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Schmidt Ocean Institute | Harvard University