Farewell to Reefs, Salt Ponds and Milkfish - Kiritimati Island

[Stacey King]

November 30, 2010, 5:57 pm By STUART SANDIN New York Times - Scientist At Work

Stuart Sandin Roadside salt ponds of Kiritimati Island. These ponds are home to productive milkfish fisheries for the island residents.Stuart Sandin of the Scripps Institution of Oceanography traveled to the Line Islands in early November to examine the coral reefs of inhabited and uninhabited islands. Here are the final two entries from his expedition.

Wednesday, Nov. 17

This morning I woke up on Kiritimati Island, the largest of the Line Islands and the most populated. The most recent census of the island, in 2005, reported 5,115 residents, and the guess is that the coming census may come close to doubling this figure. Many of the new arrivals are here because of a resettlement program initiated by the Republic of Kiribati to relieve stress on the main island of the country, Tarawa, which has a population density exceeded by few other islands.

My visit to Kiritimati was supposed to be brief. Because we had just visited the United States-protected island of Jarvis, we are required to again clear immigration and customs for the Republic of Kiribati. Yesterday, Forest Rohwer and I brought one of our small boats to shore to visit the necessary offices, a mission expected to consume a couple of hours. We spent a day and a half on the island. A big swell from the north and strong offshore winds changed the typically calm, though shallow, channel into a roiling mess of walled-up 10-foot-plus waves and white water. Not the best conditions to navigate an 18-foot inflatable boat! Fortunately the rest of the team was still offshore with clearance to get our research started, albeit under somewhat bumpy conditions.

Stuart Sandin Roads crisscross much of Kiritimati Island, passing through coconut groves, by small villages, and alongside ponds.

After three weeks of visiting small, little-inhabited islands, getting grounded on a large island with a diversity of people was not terrible. After completing our business, we rented a small car and drove out of town. The center of the island is far from dry, but instead is home to an enormous lagoon and an extensive network of isolated salt ponds. Here is where a big part of the fishing soul of Kiritimati exists. The lagoon supports a thriving population of hard-fighting bonefish, one of the biggest attractions for foreign tourists looking to test their fly-fishing prowess. Further, the ponds produce about half of the fish for the people of Kiritimati, largely composed of dinner-plate-size milkfish. Because of the high salinity of the ponds with the specific flora and fauna, the milkfish here are oily and coveted by the islanders.

Forest Rohwer The shores of the salt ponds of Kiritimati are covered with encrusting microbes that make the red color and the foamy bubbles.

Our driving tour took us past some of the salt ponds. At their centers, the ponds were a much darker shade of blue than the azure water of the coral reefs we have been visiting. But the edges of the ponds were the most stunning. A light red border about 10 feet wide ringed the ponds. Here is where Forest became excited; he is a microbiologist from San Diego State University with a specific interest in the microbial communities in extreme environments. The red border, he related, is made by microbes, and more specifically by one of the most primitive forms of microbes, the Archaea. These small organisms can live in a variety of extreme environments, in this case capitalizing on the high salt content of the ponds. These Archaea not only made the colorful framing of the ponds, but they also release a rich polysaccharide that floats to the surface. Combine a thin layer of oil with the consistent winds of Kiritimati Island, and out come bubbles. Much like kids blowing bubbles from soapy water, the island was blowing bubbles over the salt ponds. These bubbles built up into drifts along the shores, and, lo and behold, we found the snows of Kiritimati. (Note that the pun works best when using the anglicized island name, Christmas Island.)

Returning to the main town of London for the night, we made a number of friends. Whether because of the relevance to the local life or to my professional interests, the conversations often turned to fish. As the population of Kiritimati grows, there is palpable concern for continued food security. Can the ponds support the demand to produce an increasing number of milkfish for the local consumption? Further, can the ponds also support the punctuated demand for export of milkfish? Tarawa has no ponds and thus none of these tasty milkfish, so each time the national freighter boat leaves Kiritimati for Tarawa, tons of milkfish are loaded to send to friends and family in the capital. And if the milkfish are depleted, where will the people of Kiritimati find the protein to replace this resource? Can the coral reefs of the island fill this demand?

Following a day of weather-imposed grounding, we return to the rest of the team. We discuss the experiences that we had on the island and the dives of the rest of the team around the island. We have two views of Kiritimati so far, and in the remaining days of the expedition and the months to follow, our goal is to link these views.

Stuart Sandin Reef-dwelling snappers are a mainstay of the Kiribati diet. In heavily populated areas, both species pictured here become hard to find.

Sunday, Nov. 21

The end of an expedition is bittersweet. After four weeks working closely with colleagues and visiting a variety of coral reef environments, my mind is a jumble of science and emotions. We have seen the crystal-clear waters of Kingman reef filled with countless large snappers and fields of elfin boulder corals. We have visited the hyper-variable reefs of Tabuaeran, with the most consistent feature being the seeming omnipresence of three-foot-long Napoleon wrasses. We worked around Palmyra, Teraina and Jarvis, each providing a pile of vivid memories.

Most recently on Kiritimati we have seen all too clearly the footprint of humanity on coral reefs. Near the main town of London, the coral reefs are no longer living up to their name, as the reef is covered in ribbons of green seaweed with only the rare coral head poking out into the sunlight. Even the sunlight here is compromised, as the water is green and murky; the plankton, bacteria and viruses in the water column steal much of the sunlight before it reaches the bottom. As we travel farther from town, however, the reefs appear to regain their vibrancy. Although I look forward to returning home, I don’t want to stop this stream of experiences.

The goal of the expedition, however, was not to gather anecdotal observations, but instead to collect data. We have spent our time trying to understand the ecological implications of human-induced changes to coral reef structure. What happens to fisheries’ productivity when large fish are removed from a coral reef? How is the competitive outcome between corals and seaweed changed when water quality is compromised by pollution? How do extreme warm-water events affect coral growth and survivorship? The answers to these questions lie in the realm of community and ecosystem ecology, in this case linking the disciplines of fish ecology, coral and algal biology, and microbiology. We assembled our team to represent each of these specialties (with more information about the expedition available at www.coralreefsystems.org), and each member has faithfully collected masses of data to answer these questions.

Gareth Williams Research equipment being loaded for shipment home. Most samples were saved in plastic wrapping and carried home by hand.

In these final hours, the goal of the expedition is simple – get the data home. We have many types of samples helping us to understand the ecological implications of change to coral reef ecosystems. The fish team collected specimens of a few different species, investigating how species-specific patterns of fish growth vary in response to the presence (or absence) of predators. The benthic team (the group working on the corals and algae attached to the reef’s surface) collected data and samples testing how the pattern of photosynthesis and respiration on the bottom changes with alterations of the community. And the microbiology team collected water samples and DNA from the bacteria and viruses living above the reef to test whether the changes in the fish and benthic communities are complemented by changes in activity of the smallest microbial denizens of the reef. The samples from these groups are split among hard drives, freezers, dry storage and chemical storage. Getting these data home from a small island in the remote central Pacific is no easy task.

To prevent this story from being a cliffhanger, let me tell you that almost all of the data have by now arrived home safely. We have copies of the digital data in multiple locations. We have samples in freezers with buffered electronics and independent alarms in case of electrical failure. The remaining samples are in their home laboratories waiting for the next phases of processing. Our year of preparation set us up to collect the samples needed to conduct our natural experiment of the ecological dynamics that change as human activities alter coral reef community structure. The observations that we have made in the field certainly motivate our interpretation, but the substance of the expedition lies in the samples and in the hard data. Unraveling the secrets from these samples will take us at least another year.

Gareth Williams The research team preparing for a day of diving on Kiritimati Island. After leaving the ship, the team worked for a few days using local boats like this outrigger.

But for now my brain has more than enough memories and personal data to allow me a few weeks of peaceful rest. I rest assured that there remain coral reefs on the planet that exist far from the chronic disturbances of humans. Even with the presence of people, we found a number of reefs that have maintained much of the vigor and productivity seen on the uninhabited areas. There appears to be a way for people to coexist with coral reefs, and to sustainably share the resources that these habitats produce. But perhaps most reassuring is the fact that the people of Kiribati have a shared concern for maintaining their natural resources in perpetuity. We have the potential and we have the motivation. The challenge lies in the realization of this ideal known as sustainability, but the devil is truly in the details. We hope that our data and samples can help us navigate at least some of these scientific demons.