This post is by Expedition Leader Sangeeta Mangubhai.

This is blog entry posted from the field during the 2012 Phoenix Islands Marine Protected Area (PIPA) Expedition. The Phoenix Islands are an isolated island chain more than 1,000 miles southwest of Hawaii. They are part of the island nation of Kiribati, which partnered with the New England Aquarium and Conservation International to create PIPA in 2008. Today it is one of the world's largest marine protected areas and a UNESCO world heritage site. This voyage is part of a regular series of scientific expeditions to investigate coral health and study ecosystems and biodiversity.


Surface currents in the world’s oceans are like highways, transporting nutrients, plankton, and other water properties, and are part of a changing, coupled climate system. In order to understand how different parts of the ocean are connected, to predict the events we might expect in the future, and to monitor the changes our planet is undergoing, we need to map these surface currents.  Drifters are oceanographic instruments designed to accurately measure surface currents by mimicking the motion of a single parcel of seawater. A drifter is composed of two parts: a surface float containing a transmitter, and a drogue, hanging below, which is a hollow tube of canvas 60 cm in diameter and a few meters long. The transmitter regularly relays the position of the drifter to scientists on land via satellite, and the drogue ensures that the drifter accurately follows a water parcel, unaffected by the wind above. A drifter can continuously report positions for approximately two years.

Ben Hodges, researcher at Woods Hole Oceanographic Institution, describes the the science behind ocean drifters (Photo: K. Ellenbogen)

During the 2012 PIPA cruise aboard the NAI’A, several drifters will be deployed along the eastern rim of the Phoenix Islands archipelago. The prevailing westward current will likely carry these drifters near downstream islands, providing multiple realizations of the paths taken by water (and everything suspended in it) as it flows from island to island. With these current measurements, we hope to better understand how the transport of biota influences the connectivity of the islands’ ecosystems.

Ben Hodges checks drifter function prior to deployment. (Photo: K. Ellenbogen)

The PIPA cruise also provides a unique opportunity to study ocean currents over a broader area as well. Drifters aren’t the only game in town when it comes to measuring surface currents. By observing sea surface height from satellites, scientists can estimate surface currents over most of the globe (a relationship known as geostrophy), without ever leaving their cozy offices. But there’s no substitute for drifters when it comes to accurately following a parcel of near-surface water.

Deploying  a drifter from the NAI’A on 5 June 2012 during the transit from Apia, Samoa, to the Phoenix Islands, Kirbati (Photo: K. Ellenbogen)

This is particularly true near the equator—geostrophy works better at higher latitudes. Ironically, the equatorial Pacific, one of the places where drifters can contribute the most to our knowledge of ocean currents, is also one of the hardest places to maintain a population of drifters. It is less well travelled than many other parts of the world ocean, and because of the divergence of surface currents near the equator, drifters that are deployed there usually don’t stay long. That’s where we come in. During the transit of the NAI’A from Samoa to the Phoenix Islands a drifter was deployed at each degree of latitude, seeding the southern equatorial Pacific with instruments that will help fill in a perennial gap in the existing array. While waking up at 3:00 a.m. to arm, test, and deploy a drifter in dark, pitching seas can certainly be a hassle, the detailed information about currents in such a remote part of the world more than makes up for the challenges

Map of drifter deployments planned for the 2012 NAI’A PIPA cruise. Also shown are: bathymetry (color); average currents during the month of June, calculated from satellite measurements of sea surface height (arrows); and the planned arrival date of the NAI’A at each site.

-Ben Hodges

This is good news! Calm seas and work beginning -- as we had hoped.
So, where is Kanton Island, and what is the team planning to do there?

Kanton Island

WHOI scientists remove a core sample from a massive star coral in a reef north of St. Thomas, U.S. Virgin Islands. They will do the same during this expedition to the Phoenix Islands Protected Area. (Photo: WHOI)

A fish otolith (ear bone) (Photo: WHOI)

Dr. David Obura measures coral health in PIPA. Photo by R. Rotjan

I was up at the crack of dawn – I am always like this when I am excited, and this morning my thoughts were filled with Phoenix Islands as I started counting down the final 24 hours. The rest of the team is somewhere in the sky and I headed out to buy the last minute things we needed because once we leave there will be nothing but open ocean, and with the exception of Kanton, uninhabited islands.

The Nai'a, ready to set sail for PIPA, in Apia Harbor

My mission this morning was to buy rat traps! There was a massive effort in 2009 to clear three of the PIPA atolls of rats that had been introduced and were impacting local bird populations. The Phoenix Islands, due to their isolation, have significant bird numbers, with five of the eight islands being important bird areas. The boat has been fumigated twice in Fiji and we are packing extra traps to place on the boat in case we get a few ‘naughty stowaways’ from Samoa. The Kiribati government has developed biosecurity protocols to help protect these islands, and we will be following them exactly to make sure we do not impact the marine or terrestrial life of these atolls.

We also hope to find time to visit some of the islands and see if the previous eradication programs have remained effective.

Traditional Vaka

My fellow Pacific Islander, Jay Andrew from the Palau International Coral Reef Center, who is an expert on collecting coral cores to study climate change, arrived today from Palau. As we headed to the harbor to see the ocean voyaging ‘vakas’, I was reminded and humbled by the long voyages that Pacific Islanders did across the Pacific. There were no compasses, no GPS, no radar, no radio - yet these Islanders used the seas and skies to guide them across wide expanses of open ocean.

Sangeeta, Jay, and Sue overlooking the Apia harbor

Of course, we are traveling with the Nai’a who is both outfitted with all the latest navigation tools and technology and we are bring out own inflatable hyperbaric chamber too in case someone gets decompression sickness! As we looked out to sea to watch the sun setting over the Pacific we saw the Nai’a patiently waiting for our team of scientists to arrive.

Then, to sea!

--Sangeeta

I arrived yesterday in Apia, the capital of Samoa, just in time to celebrate the country’s 50th year of independence. It is the first time in 7 years that I have been back to the Central Pacific – the last time I was here was in 2005, for the third expedition to the Phoenix Islands.

First order of business upon arrival was sleep – I had to take two overnight flights from Bali, Indonesia to get here, and there was very little keeping my eyelids open when I arrived. Three hours later I emerged bleary-eyed and went straight to the Conservation International office, which is both my office and home for the next two days. I spent my day catching up with Sue Taei, who is a key supporter of the conservation and management of the Phoenix Islands Protected Area for Kiribati. She is a wealth of knowledge on what is happening in the Pacific!