A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati

Casey Saenger^*¹ , Michael Miller² , Rienk H Smittenberg¹^,3 and Julian P Sachs¹^,3

¹Massachusetts Institute of Technology, Department of Earth Atmospheric and Planetary Science, 77 Massachusetts Avenue, Building E34-205, Cambridge, MA 02139, USA

²University of Cincinnati, Department of Biology, Cincinnati, OH 45221, USA

³University of Washington, School of Oceanography, Box 355351, Seattle, WA 98195, USA

author email corresponding author email* Contributed equally

Saline Systems 2006, 2:8doi:10.1186/1746-1448-2-8


Published:	3 July 2006

Abstract

The equatorial Pacific Ocean atoll islands of Kiritimati and Teraina encompass great physical, chemical and biological variability within extreme lacustrine environments. Surveys of lake chemistry and sediments revealed both intra- and inter-island variability. A survey of more than 100 lakes on Kiritimati found salinities from nearly fresh to 150 ppt with the highest values occurring within the isolated, inland portions of the island away from the influence of groundwater or extreme tides. Dissolved oxygen (DO) and pH values also showed considerable variability with a less regular spatial pattern, but were both generally inversely related to salinity. Series of lakes, progressively more isolated from marine communication, present a modern analog to the chemical and morphologic evolution of presently isolated basins. Sediments on both islands consist of interbedded red and green silt, possibly degraded bacterial mat, overlying white, mineralogenic silt precipitate. Variability may be indicative of shifts in climatological parameters such as the El Niño Southern Oscillation (ENSO) or the Pacific Intertropical Convergence Zone (ITCZ).