Ebook: Environmental Change and Response in East African Lakes

The idea for this book was born at the June 1996 meeting of the IDEAL Steering Committee in Milwaukee, Wisconsin. We had just completed a successful and stimulating special symposium during the annual meeting of the American Society for Limnology and Oceanography, and enthusiasm was running high for the production of a volume that could assemble in one place the scientific findings that were starting to emerge from East Africa. IDEAL, an International Decade for the East African Lakes, had ended one round of field investigations, many of which had been centered on Lake Victoria. As the climatologists, geologists, paleolimnologists, and biologists displayed their results and debated interpretations, it appeared that some paradigms were shifting, and that new explanations of climate history and modem processes were taking shape. The Steering Committee endorsed the production of a volume that would draw together the different research results that were emerging and which would be representative of the scope of science issues that exist within IDEAL. This book follows in the spirit of The Limnology, Climatology, and Paleoclimatology of the East African Lakes, published in 1996, but has a somewhat different purpose. The previous publication also included original science results, but it was conceived to review the state of knowledge, identify critical problems, and point to new paths of inquiry. It accompanied the development of our first Science and Implementation Plan for the East African Lakes.

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The International Decade for the East African Lakes (IDEAL) has completed its first phase of field studies, and has assembled in this volume its findings, ranging from seismic reflections to historical drought chronologies, geochemistry, and modern food web processes. Multidisciplinary IDEAL investigations are summarized and integrated, revealing that modern changes in the East African lakes share a continuity with past variations in climate and environmental conditions. Results from an array of disciplinary perspectives and evidentiary lines point to the causative role of modern climate variation in the deterioration of Lake Victoria, one of the most prominent lakes on the planet.
The ancient conditions of Victoria and other East African lakes are reconstructed with forensic tools that permit measurements of paleomagnetism, pollen and algal fossils, biogenic minerals, depositional carbonates, and bulk geochemistry. Oral traditions, explorer's journals, and records of the ancient Nile provide human testimonies that parallel the physical record. Studies of biological production, nutrient dynamics, and lower food web processes reveal how the lake communities function at the trophic levels that leave sedimentary evidence in the form of organic matter, minerals, and fossils. Comparisons of weather records and lake properties demonstrate a striking change in climate conditions during the present century with causal links to lake conditions. The collected scientific perspective makes a compelling case for the worth of integrated studies across a spectrum of traditional specialties when they are focused on complex environmental issues.

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The International Decade for the East African Lakes (IDEAL) has completed its first phase of field studies, and has assembled in this volume its findings, ranging from seismic reflections to historical drought chronologies, geochemistry, and modern food web processes. Multidisciplinary IDEAL investigations are summarized and integrated, revealing that modern changes in the East African lakes share a continuity with past variations in climate and environmental conditions. Results from an array of disciplinary perspectives and evidentiary lines point to the causative role of modern climate variation in the deterioration of Lake Victoria, one of the most prominent lakes on the planet.
The ancient conditions of Victoria and other East African lakes are reconstructed with forensic tools that permit measurements of paleomagnetism, pollen and algal fossils, biogenic minerals, depositional carbonates, and bulk geochemistry. Oral traditions, explorer's journals, and records of the ancient Nile provide human testimonies that parallel the physical record. Studies of biological production, nutrient dynamics, and lower food web processes reveal how the lake communities function at the trophic levels that leave sedimentary evidence in the form of organic matter, minerals, and fossils. Comparisons of weather records and lake properties demonstrate a striking change in climate conditions during the present century with causal links to lake conditions. The collected scientific perspective makes a compelling case for the worth of integrated studies across a spectrum of traditional specialties when they are focused on complex environmental issues.
Content:
Front Matter....Pages i-xix
History and Ontogeny of IDEAL....Pages 1-6
Historical Fluctuations of Lake Victoria and Other Lakes in the Northern Rift Valley of East Africa....Pages 7-35
Ancient Analogues for Recent Environmental Changes at Lake Victoria, East Africa....Pages 37-46
Initial Results of 1995 IDEAL Seismic Reflection Survey of Lake Victoria, Uganda and Tanzania....Pages 47-57
Environmental Magnetism of Late Pleistocene / Holocene Sequences from Lake Victoria, East Africa....Pages 59-73
Biogenic Silica Profiles in Holocene Cores from Lake Victoria: Implications for Lake Level History and Initiation of the Victoria Nile....Pages 75-88
Role of Apatite Weathering in the Eutrophication of Lake Victoria....Pages 89-98
Lake Victoria Plankton Ecology: Mixing Depth and Climate-Driven Control of Lake Condition....Pages 99-116
Caridina Nilotica: Spatial Distribution and Egg Production in Lake Victoria, Uganda....Pages 117-124
Low-Oxygen Tolerance of the Atyid Prawn, Caridina Nilotica, in Lake Victoria (East Africa): Implications for Refuge from Nile Perch Predation....Pages 125-133
Secondary Production by the Lake Fly Chaoborus in Lake Victoria, East Africa: Implications for Trophic Dynamics of the Modern Lake....Pages 135-145
Abrupt Climatic Changes Associated with the Arid Younger Dryas Interval in Africa....Pages 147-156
Nutrients and Plankton Biomass in the Rift Lake Sources of the White Nile: Lakes Albert and Edward....Pages 157-172
Comparison of Isotopic Records in Abiogenic and Biogenic Calcite from Lake Turkana, Kenya....Pages 173-190
A Comparison Between the Stable Isotopic Composition of Early Holocene and Late Pleistocene Carbonates from Lake Malawi, East Africa....Pages 191-206
Fluctuations of Rift Valley Lakes Malawi and Chilwa During Historical Times: A Synthesis of Geological, Archaeological and Historical Information....Pages 207-231
Back Matter....Pages 233-236

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The International Decade for the East African Lakes (IDEAL) has completed its first phase of field studies, and has assembled in this volume its findings, ranging from seismic reflections to historical drought chronologies, geochemistry, and modern food web processes. Multidisciplinary IDEAL investigations are summarized and integrated, revealing that modern changes in the East African lakes share a continuity with past variations in climate and environmental conditions. Results from an array of disciplinary perspectives and evidentiary lines point to the causative role of modern climate variation in the deterioration of Lake Victoria, one of the most prominent lakes on the planet.
The ancient conditions of Victoria and other East African lakes are reconstructed with forensic tools that permit measurements of paleomagnetism, pollen and algal fossils, biogenic minerals, depositional carbonates, and bulk geochemistry. Oral traditions, explorer's journals, and records of the ancient Nile provide human testimonies that parallel the physical record. Studies of biological production, nutrient dynamics, and lower food web processes reveal how the lake communities function at the trophic levels that leave sedimentary evidence in the form of organic matter, minerals, and fossils. Comparisons of weather records and lake properties demonstrate a striking change in climate conditions during the present century with causal links to lake conditions. The collected scientific perspective makes a compelling case for the worth of integrated studies across a spectrum of traditional specialties when they are focused on complex environmental issues.
Content:
Front Matter....Pages i-xix
History and Ontogeny of IDEAL....Pages 1-6
Historical Fluctuations of Lake Victoria and Other Lakes in the Northern Rift Valley of East Africa....Pages 7-35
Ancient Analogues for Recent Environmental Changes at Lake Victoria, East Africa....Pages 37-46
Initial Results of 1995 IDEAL Seismic Reflection Survey of Lake Victoria, Uganda and Tanzania....Pages 47-57
Environmental Magnetism of Late Pleistocene / Holocene Sequences from Lake Victoria, East Africa....Pages 59-73
Biogenic Silica Profiles in Holocene Cores from Lake Victoria: Implications for Lake Level History and Initiation of the Victoria Nile....Pages 75-88
Role of Apatite Weathering in the Eutrophication of Lake Victoria....Pages 89-98
Lake Victoria Plankton Ecology: Mixing Depth and Climate-Driven Control of Lake Condition....Pages 99-116
Caridina Nilotica: Spatial Distribution and Egg Production in Lake Victoria, Uganda....Pages 117-124
Low-Oxygen Tolerance of the Atyid Prawn, Caridina Nilotica, in Lake Victoria (East Africa): Implications for Refuge from Nile Perch Predation....Pages 125-133
Secondary Production by the Lake Fly Chaoborus in Lake Victoria, East Africa: Implications for Trophic Dynamics of the Modern Lake....Pages 135-145
Abrupt Climatic Changes Associated with the Arid Younger Dryas Interval in Africa....Pages 147-156
Nutrients and Plankton Biomass in the Rift Lake Sources of the White Nile: Lakes Albert and Edward....Pages 157-172
Comparison of Isotopic Records in Abiogenic and Biogenic Calcite from Lake Turkana, Kenya....Pages 173-190
A Comparison Between the Stable Isotopic Composition of Early Holocene and Late Pleistocene Carbonates from Lake Malawi, East Africa....Pages 191-206
Fluctuations of Rift Valley Lakes Malawi and Chilwa During Historical Times: A Synthesis of Geological, Archaeological and Historical Information....Pages 207-231
Back Matter....Pages 233-236
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