The Expedition Begins
By Stuart Sandin
Our destination is the Line Island archipelago of the Republic of Kiribati, but today we are in the Society Islands of French Polynesia. The research team has assembled here in Tahiti to meet our vessel, the Expedition Yacht Hanse Explorer. In a few hours we will be escorted out of the port and into the open Pacific Ocean – our first stop is Flint Island, the southernmost of the Line Islands.
For most of the team, this will be the first visit to the southern Line Islands. It is not surprising that this will be a virgin voyage for most people, given that all five of these Kiribati islands are uninhabited, and perhaps more importantly, lie very far from any population centers. The closest ports are Papeete, Tahiti, to the south (about 400 nautical miles away) and Honolulu, Hawaii, to the north (1500-2000 nautical miles away). The remoteness, however, has conferred de facto protection to the coral reefs of these islands, with no fishing, no pollution, and effectively no human impacts. This is the context for the expedition, to learn more about the ecology of coral reefs that exist outside of the local influence of humans.
Based on previous work from our teams at Scripps Institution of Oceanography (UC San Diego) and San Diego State University, we began to learn about so-called ‘pristine’ coral reefs. Reefs without fishing have more fish (no surprise here!), more corals and calcifying organisms, fewer fleshy seaweeds and fewer microbes. In this absence of human manipulation, coral reefs appear to have tremendous capacity to thrive and rebound from disturbance. But also without human impacts, we still see quite a bit of variability in the composition and abundance of species inhabiting these coral reefs. Even in the absence of human activity, we have begun to learn that physical and chemical characteristics of the environment can have a profound influence on coral reef structure and dynamics.
The five islands of the southern Line Island archipelago provide for us an invaluable natural experiment. Based on the local oceanography of the equatorial central Pacific, there is a strong gradient of water temperature and nutrient concentration across latitude. Oddly enough the islands closer to the equator have cooler water and more nutrients. This is ‘odd’ because we typically think that the world is warmest along the equator and cooler further away. However, ocean temperature is influenced not only by the amount of sun reaching the surface but also based upon how much deep water (where cooler, more nutrient-rich waters exist) is brought up, or upwelled, into the shallows. In the Line Islands, there is more upwelling near the equator, and thus more of the cool, nutrient-rich water reaching the surface and bathing coral reefs. From south to north in the southern Line Islands there is a shift from waters that are warm and gin-clear (i.e., no nutrients to fuel growth of microalgae – also known as phytoplankton – in the water column) to waters that are cooler and more opaque (i.e., more nutrients fueling photosynthesis of phytoplankton).
The goal of our expedition is thus to test how the ecology of coral reefs is linked to variability in oceanographic conditions in the absence of human activities, such as fishing and pollution. Do more nutrient-rich reefs support more fish growth? More production of invertebrates? More algal growth? More microbiological growth? We know that reefs look different in this part of the central Pacific. However, we don’t really know the nature of the linkages between biology and oceanography, let alone how oceanography can drive how these reefs are structured and how they function for organisms at every level of the food web.
During this month-long expedition we will be exploring these ideas. In this blog, we will highlight the research through writings from many members of our terrific team. We aim to explore many facets of the biology and ecology of these southern Line Islands, as well as to discuss the potential for conservation and management here and across the tropics. The stories will be new, for the writers and the readers alike. And for this we are excited.
But as of right now, we are struggling our way through the final hours of fixes, packing, and preparations for the expedition. A bit more time in civilization, then it is all ‘uninhabited’ from here on out!
So begins our expedition to the southern Line Islands.