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Lake Valencia, Venezuela

Lake Valencia, Venezuela. Colleen Nagel Aquatic Ecology of the Tropics. North-Central Venezuela Surface Area: 350 km^2 Metamorphic rocks from marine sediments (bedrock). Lake Valencia, Venezuela.

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Lake Valencia, Venezuela

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  1. Lake Valencia, Venezuela Colleen Nagel Aquatic Ecology of the Tropics

  2. North-Central Venezuela • Surface Area: 350 km^2 • Metamorphic rocks from marine sediments (bedrock)

  3. Lake Valencia, Venezuela • Aragua Valley : Cordillera de las Costas to the north and the Serrania del Interior to the south • Northern Hemisphere • ITCZ • Depth~40 meters • Warm, monomictic lake, hyper-eutrophic • Turmero, Venezuelan city, in catchment of Lake Valencia

  4. Lake Inputs and Interactions • Precipitation: 1,000-1,500mm • Loss of water: Evaporation and subsurface out-seepage • During high lake level periods water is lost from outflow over sill at 427 m in SW part of lake

  5. Water Inflow

  6. Two-year Weather and Water Temperature (Lewis, 1983)

  7. Geochemical record of anthropogenic impacts on Lake Valencia, Venezuela (Xu and Rudolf, 2009) Fig. 1. Geographic location of Lake Valencia, Venezuela. X denotes the sampling site.

  8. Primary Productivity • Average net photosynthesis rate: 7.5 gCm^-2d^-1 • High primary productivity lowers O2 levels in deeper water • Cyanobacteria (90% of plankton biomass) • dominate over diatoms and green algae

  9. Geochemical Parameters

  10. Plants and Organisms • Emerged macrophytes • Floating macrophytes • Submerged macrophytes • Phytoplankton • Microcystis • Zooplankton • Benthos • Fish: Sarotherodonmossambicus (tilapia), Peteniakraussii, Symbranchusmarmoratus (freshwater eel), and Rhamdiaquelen (catfish) Petenia kraussii

  11. Human Impacts • Population of Aragua Valley: 2 million people • Main crops: Sugar cane, vegetables, fruit trees (banana, mango, citrus), tobacco, cotton, and maize • Industrialized • Lake salinity has increased over the past several decades, due to input waters being diverted and groundwaters were pumped for agricultural irrigation. • Raw sewage discharge, high nutrient concentration and high rates of primary production

  12. Environmental Recovery: Ministery of Environment and Natural Resources (MARNR) • Financed by Interamerican Bank for Development • Laws: • Organic Law for Environment (1976) • Ordinance for Classification of Waterbodies According to Its Use (1978) • Control natural resources, waterbodies water treatment, and industrial development

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