Comparative analysis of organic matter and carbonate mineral distribution in shallow water surface sediments off the forested Kalande and deforested Ngelwa watersheds entering Lake Tanganyika, Tanzania

Introduction The impacts of watershed deforestation on lacustrine environments can dramatically affect the productivity of the littoral zone and strongly influence sedimentation rates. Many watersheds flowing into Lake Tanganyika (3°18’8°47’S, 29°05’ 31°18’E) from northern Kigoma region, Tanzania are currently experiencing the effects of deforestation to accommodate high human population densities and increasing cultivation of cassava and other crops (O’Reilly et al., 2005). These disturbed watersheds exist in stark contrast to protected watersheds located within nearby Gombe Stream National Park, where human impact has recently been more tightly controlled. Differences between forested and deforested watersheds are manifested by major increases in sediment accumulation rates in the latter (Cohen et al., 2005a) and related differences in organic matter type and carbonate concentrations within near shore sediment deposits.