Geophysical benthic habitat mapping in Lake Tanganyika (Tanzania): Implications for spatial planning of small-scale coastal protected areas

Joseph S. Lucas, Michael M. McGlue, Ismael A. Kimirei, Michael J. Soreghan, Athanasio Mbonde, Kevin M. Yeager, Peter Limbu, Colin Apse, Peter B. McIntyre

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Optimizing community-based fisheries management to enhance both food resource and biodiversity conservation in large lakes requires detailed knowledge of benthic habitats, which determines suitability for fish breeding sites. This information is unavailable for much of Lake Tanganyika, whose fisheries are threatened by a warming climate, destructive harvesting practices, and sediment pollution. Lake Tanganyika possesses a remarkably diverse fish population. Much of this is concentrated in areas with water depths less than 30 m and on rocky substrate. Here, geophysical tools were used to map benthic habitats in a 21 km2 co-management area of the lake in western Tanzania. Echosounding defined the position of the 30-m isobath, which varies with proximity to deltas and rift-related faults. Side-scan sonar discriminated among four unique substrates: crystalline bedrock, calcite-cemented sandstones, mixed siliciclastic sediments, and shell-rich sediments. Unlithified mixed silts and sands constitute over 91% of the study area. Rocky substrate composed of crystalline basement and calcite-cemented sandstone make up the less than 9% of the substrate in the study area. Crystalline bedrock was present from 0 to 30 m water depth, whereas the calcite-cemented sandstones were encountered in water less than 5 m deep. The spatial organization of rocky substrates is interpreted to be controlled by basin structure and lake level history; these habitats make ideal targets for establishing new small-scale protected areas. The techniques illustrated in this study are broadly applicable elsewhere in Lake Tanganyika, and to other large lakes where data needs for placing conservation reserves are lacking.

Original languageEnglish
Pages (from-to)243-254
Number of pages12
JournalJournal of Great Lakes Research
Volume46
Issue number2
DOIs
StatePublished - Apr 2020

Bibliographical note

Funding Information:
This research was carried out as a portion of the first author’s graduate program at the University of Kentucky . The project was funded by the Society of Exploration Geophysicists Geoscientists Without Borders Program (Award #201401005), the National Science Foundation (EAR-1424907) and supplemented by small grants from the University of Kentucky. Research was lawfully conducted with permits obtained from COSTECH. Logistical support was graciously provided by the Tuungane Project staff in Buhingu and the Tanzania Fisheries Research Institute-Kigoma. Vessel support was provided by the Tanzania Fisheries Enforcement patrol at Mahale. The chief warden and staff of the Mahale National Park are gratefully acknowledged for their assistance in facilitating the project. Special thanks to M. Mukuli, P. Ryan, E. Ryan, A. Gravina, J. Busch, and J. Golcher Benavides for assistance with fieldwork.

Funding Information:
This research was carried out as a portion of the first author's graduate program at the University of Kentucky. The project was funded by the Society of Exploration Geophysicists Geoscientists Without Borders Program (Award #201401005), the National Science Foundation (EAR-1424907) and supplemented by small grants from the University of Kentucky. Research was lawfully conducted with permits obtained from COSTECH. Logistical support was graciously provided by the Tuungane Project staff in Buhingu and the Tanzania Fisheries Research Institute-Kigoma. Vessel support was provided by the Tanzania Fisheries Enforcement patrol at Mahale. The chief warden and staff of the Mahale National Park are gratefully acknowledged for their assistance in facilitating the project. Special thanks to M. Mukuli, P. Ryan, E. Ryan, A. Gravina, J. Busch, and J. Golcher Benavides for assistance with fieldwork.

Publisher Copyright:
© 2020 International Association for Great Lakes Research

Keywords

  • Habitat mapping
  • Lake Tanganyika
  • Littoral zone
  • Rift lake
  • Sediment pollution
  • Side scan sonar

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

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