TY - JOUR
T1 - Geophysical benthic habitat mapping in Lake Tanganyika (Tanzania)
T2 - Implications for spatial planning of small-scale coastal protected areas
AU - Lucas, Joseph S.
AU - McGlue, Michael M.
AU - Kimirei, Ismael A.
AU - Soreghan, Michael J.
AU - Mbonde, Athanasio
AU - Yeager, Kevin M.
AU - Limbu, Peter
AU - Apse, Colin
AU - McIntyre, Peter B.
N1 - Publisher Copyright:
© 2020 International Association for Great Lakes Research
PY - 2020/4
Y1 - 2020/4
N2 - 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.
AB - 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.
KW - Habitat mapping
KW - Lake Tanganyika
KW - Littoral zone
KW - Rift lake
KW - Sediment pollution
KW - Side scan sonar
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U2 - 10.1016/j.jglr.2020.01.010
DO - 10.1016/j.jglr.2020.01.010
M3 - Article
AN - SCOPUS:85078861437
SN - 0380-1330
VL - 46
SP - 243
EP - 254
JO - Journal of Great Lakes Research
JF - Journal of Great Lakes Research
IS - 2
ER -