Linking watershed disturbance with nearshore sedimentation and the shell beds of Lake Tanganyika (Mahale Mountains, Tanzania)

James Busch, Michael Soreghan, Kirsten de Beurs, Michael McGlue, Ismael Kimirei, Andrew Cohen, Emily Ryan

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Extensive deposits of shell-rich sediments in the nearshore environment of Lake Tanganyika, Africa, form a unique habitat for a diverse group of endemic gastropods, crustaceans, fish and sponges, among other organisms. Anthropogenic alteration of the lake’s hinterland from deforestation, fires, and agriculture threaten this crucial habitat through sediment pollution of the littoral environment. This study examines the sedimentology of these nearshore shell beds along a study area north of the Mahale Mountains (Tanzania) to test whether varying levels of watershed disturbance, determined by analysis of satellite imagery, within three moderately sized watersheds (> 100 km2) results in sedimentological differences offshore. The results show that shell beds adjacent to disturbed watersheds (Lagosa and Rukoma) contain more fine-grained sediment compared to shell beds offshore of the undisturbed watershed (Katumbi). Widespread burning, clearance, and land cultivation, and rains of the wet season are causal factors that result in significant differences in fine-grained sedimentation, larger sediment plumes offshore, and increased shoreline progradation. In areas most affected by sedimentation, sponges are largely absent, and shell coverage, which is a measure of fish-nesting capabilities, is lower. The discovery of a small population of live Neothauma tanganyicense offshore of the Katumbi river suggests that the presence of shell-bed forming gastropods in front of a relatively low disturbance watershed, and their conspicuous absence offshore of the other two watersheds, could be related to recent watershed disturbance and increased sedimentation. The increased fine-grained sedimentation and limited shell production by the reduced modern gastropod populations may signal that the shell-bed ecosystem of Lake Tanganyika is at risk.

Original languageEnglish
Article number514
JournalEnvironmental Earth Sciences
Issue number13
StatePublished - Jul 1 2018

Bibliographical note

Funding Information:
Acknowledgements This work was funded by the National Science Foundation (EAR-1424907) and supported by a grant from the Society of Exploration Geophysicists Foundation Geoscientists Without Borders program (Grant #201401005). This research was conducted under the Tanzania Commission for Science and Technology Permit 2016-3-1-NA-2011-87 We also thank the DigitalGlobe Foundation for providing proprietary satellite imagery data for the study; Colin Apse and Dan Kelly (The Nature Conservancy) for their support in sharing GIS

Publisher Copyright:
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.


  • Lake Tanganyika
  • Lake sedimentation
  • Remote sensing
  • Shell beds
  • Watershed disturbance

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Water Science and Technology
  • Soil Science
  • Pollution
  • Geology
  • Earth-Surface Processes


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