A never ending story
Tuesday | August 16, 2005
The view was magnificent, a turquoise lagoon surrounded by a belt of coconut trees and a few bright green patches of native trees under a delicate blue sky dotted with cottony clouds. We were all wet from the splashes, trying to protect our camera bags from the salty water. Behind us, standing proudly and driving our small aluminum boat, was Johny Mote. Johny epitomizes the human adventure of the Kiribati islanders. It is a story of development and adaptation, and one of environmental degradation as well.
Born in Tarawa, the atoll-capital of the Kiribati Republic located almost 2,000 miles west of Tabuaeran atoll, Johny spent his childhood in a place where human population was about to explode. When the population reached several tens of thousands, the government of Kiribati decided to ship people to other islands in order to prevent a societal collapse. These people became exiles in their own country. Kiritimati received a few thousand of them during the last decades, Johny among them.
Johny spent some years in Kiritimati, and then moved to the remote Teraina island where he lived for seven years. Teraina is resupplied by a cargo ship that visits the atolls every other month. However, things often go wrong in paradise, and the ship is occasionally delayed for weeks. When no food products from Australia or the United States are available, the easiest option is to fish. The population of Tarawa depleted the reef resources and polluted the lagoon, and the inhabitants of Kiritimati and Tabuaeran are on their way to deplete their fishes too.
After the years in Teraina, Johny finally moved to Tabuaeran, where he lives with his two daughters. While many other islanders moved into the seaweed farming business, he opened a small convenience store at English Harbour, and eventually became the business representative at the local council. He does not want to go back to Tarawa or even Kiritimati. He is happy in an atoll where life moves at a healthy pace, where rush hour occurs every other week when hundreds of tourists arrive on a cruise ship. For a few hours they take over English Harbour, buy handicrafts, and empty Johny's store of beer. Then come two weeks of relative tranquility, with some fishing to complement the diet with fresh seafood.
This might seem like a life in balance with the environment for the cruise ship visitor who does not leave the premises at English Harbour. However, there is talk of a government plan to move more people from Tarawa to Kiritimati and Tabuaeran. People like Johny will be happy to move from crowded and unhealthy Tarawa to less populated atolls. But if population in Tarawa continues growing uncontrolled, soon there will be no empty islands anymore. Both people and reefs will suffer. Paradise? Perhaps, but only for a while.
Our portion of the cruise officially ends tomorrow, when we fly from Palmyra to Honolulu. The trip was a huge success - we have collected over 1000 lbs of coral during this expedition, which amounts to more than 40 meters of drilled coral cores. Why have we collected so many coral samples, you might ask? Well, we often asked ourselves the same thing as we hauled heavy boulders and drilling equipment across shadeless beaches, as our biological colleagues prepared for their scuba dives. But the answer is simple: we seek to reconstruct past tropical Pacific climate changes (including El Niño events) from corals, both young and old. Such information may provide clues as to how the tropical Pacific climate system is responding to anthropogenic climate forcing. Are late 20th century El Niño events more frequent and more intense than those of the recent past? Have background climate patterns (average ocean temperature, rainfall, or circulation patterns) changed appreciably over the last several decades?
Our field plan for this trip was fairly straightforward: drill as many fossil corals as possible from each of the islands, and drill the longest core possible from a living coral colony on Tabuaeran. Our field team was composed of myself, Jordan Watson, and Kristy Dahl. Jordan is uber-tech-extraordinaire for my collaborator Chris Charles, while Kristy is a soon-to-be postdoc in Chris' lab at Scripps. Our research uses massive corals of the genus Porites, which can live for several centuries, to track past temperature, rainfall, and water mass circulation changes that are recorded in the geochemistry of the coral skeleton. The fossil corals that are scattered on beaches contain records from many centuries ago. We use uranium-thorium radiometric dating techniques to determine when the fossil corals grew on the coral reef. Previous experience on Palmyra and Fanning has taught us that a 6000-yr-old coral boulder looks exactly the same as a 50-yr-old boulder! So that means that we must collect every single fossil coral that we can find, assuming that it might cover the time interval that we are interested in. Hence the tons of fossil coral that we drilled in six long days on Christmas Island. The drill we use to drill the fossil coral cores was designed to drill corals underwater - it is powered by hydraulics and is combined with a very finicky seawater pump to flush the drill cuttings as we drill. At the end of our fossil coral hunt, our longest core was 110cm long. Assuming growth rates of approximately 1.5cm/yr, that amounts to a 70-yr-long record. It could span from 100A.D. to 170A.D. or it could span from 1850A.D. to 1920A.D. - we eagerly await the U/Th dates from the new cores, which will be ready in 2-3 months. One thing is guaranteed, that the new cores will provide glimpses of El Niño events that likely affected fledgling cultures many centuries ago, just as modern-day El Niño events affect societies all over the world.
The second component of our field mission involved recovering a core from a living coral on Tabuaeran that can be used to calibrate the relationship between climate parameters and coral geochemistry. This task involved a very different set of scientific, logistical, and safety considerations than the land-based drilling, which while labor-intensive, was relatively straightforward. First, we spent several dives scouting the leeward coral reefs for a suitable Porites coral colony to drill. We hoped to recover the longest record possible, while avoiding any visible surface irregularities, like burrowing worm and clams and fish scars. Eventually we settled on a near perfectly hemispheric 50cm-diameter head in 30 feet of water. Next we had to discuss how we would manage to get Jordan and I, the drill itself, and our drilling tools down to the drill site and back up to the surface safely, while at least one other person monitored the hydraulic and seawater pumps on the boat, both parties connected by 100 feet of unruly hoses. The photographer and videographer would capture the procedure on film. The following day, over the course of two dives, we drilled over 90cm of core from the moderately-sized Porites colony. As with all complex procedures, the beginning moments involved a steep learning curve, but after five minutes of fighting the surge and the 80-lb drill, Jordan and I hit our groove (literally), and the drilling progressed quickly and smoothly thereafter. Kristy, armed with ear protection, manned the pumps on the boat. Jordan and I plugged the coral to prevent burrowing organisms from colonizing the unprotected drill hole. Studies have shown that the coral will grow over the plug within 2-3 years, and I look forward to diving on the reef in several years to check on how the coral is recovering.
Our scientific missions accomplished, I turned my attention to organizing some informal presentations at the elementary and middle schools on Tabuaeran. I tried my best to convey the science behind my repeated visits to Tabuaeran, and passed around a section of the Porites colony we had drilled just the day before. The teachers translated for me, and the children were either very well-behaved, genuinely interested, or both. Of course, during the question and answer session, most of them wanted to know about America, where I lived, what children their age do for fun in the US, and most obviously and importantly, how my scientific investigations would benefit Tabuaeran in the future. I can only offer that hopefully, when all the scientists on the White Holly finish their studies of the Line Island coral reefs, we will be able to help them preserve the beauty and vitality of their reef ecosystem. After my talk, I was showered with gifts, including 50 shell necklaces, 20 green coconuts, 2 large pumpkins, and a large hand-carved mask. Later that day, I took ten teachers out to the White Holly for a tour of the boat. They were mesmerized by some coral polyps under the microscope, and peppered the scientists with questions. Vince and Joanne donated a computer to the middle school, and Cody threw in some school supplies, which are in short supply on the island.
The cruise was a great success for us scientifically, and sailing with an interdisciplinary group of scientists was stimulating and fun. I am confident that insights concerning past and future coral reef health across the Line Islands will only come through the combined expertise of many different marine scientists, and I look forward to sharing data and ideas in the years to come.