Aquatic Ecology of the Tropics

1
Aquatic Ecology of the Tropics

• Overview and brief historical context
• Geodynamics
• Origin of lakes
• Tropical climates 
• Morphometry, zonations

2

• Limnology was born on the shores of Lake Geneva
  (Switzerland) and developed mostly in Europe and
  North America.
• Foci over time lake descriptions, typology
  (1920-1930), energy flow problems (1940-1950),
  pollution (eutrophication) of aquatic ecosystems,
  aquatic ecosystem restoration.
• This remarkable development in limnology
  concerned almost exclusively cold and temperate
  lakes.

3
Tropical aquatic systems

• Dont get attention from the scientific and
  management community they need
• Some do, but our general understanding of the
  ecology and hydrology of wet ecosystems in this
  large and heterogeneous region is only developing
  slowly.
• Little know about extent and distribution of
  tropical aquatic systems (wetlands in particular)
• No data on rates of wetland losses due to
  development (thought to be high but are
  essentially unknown).
• Development pressures appear to be intensifying
  and the lack of data hinder wetland preservation
  and sustainable management.

4
(50 million km2 of land)
5
Some scientific expeditions to exotic regions of
the world that produced sporadic data (preserved
specimens of aquatic plants and animals for
museums and herbaria of Europe and America).
6
Kyoga
Albert
Edward
Victoria
Kivu
Tanganyika
Rukwa
7
Following this early descriptive phase of animal
and plant collections, more sustained field
expeditions in specific localities were organized.
Importance of taxonomy! 
8
(No Transcript)
9

• Since 1980s, increased attention (and actually
  some pioneer textbooks) on the subject of
  tropical aquatic ecology
• Still, even today, many regions in the tropics
  remain mysterious areas with unknown diversity.
• Scientific interest in tropical aquatic systems
• species diversity, taxonomy, energy flow, ecology
• Economic and socio-cultural importance
• species extinction, population growth and use of
  lakes for fisheries, waterborne diseases,
  drinking water supply. 

10

• Can tropical ecosystems be understood from
  principles that apply to temperate systems?
• Some principles easily transfer across latitude
  (e.g., the response of phytoplankton to light)
• Many others are remarkable different
• stratification
• nutrient cycling and material turnover rates
• biological components (diversity, role of fish)
• trophic cascades
• floodpulses
• growing seasons
• ecosystem resilience
• management issues

11
Aquatic Ecology of the Tropics

• Overview and brief historical context
• Geodynamics
• Origin of lakes
• Tropical climates 
• Morphometry, zonations

12
Geodynamics
13
Earths crustal plates and plate tectonics
(geologic processes resulting from plate
movements)
14
San Andreas fault California
15
The history of continental drift
16
Rifting A geologic term that describes the
process that occurs when land sinks between two
parallel faults.
17
Kyoga
Albert
Edward
Victoria
Kivu (2,700 km2, zmax240m)
Tanganyika (32,900 km2, zmax1,470m)
Comparison Lake Erie 25,700 km2, zmax64m Lake
Michigan 57,800 km2, zmax280m
Rukwa
18
Aquatic Ecology of the Tropics

• Overview and brief historical context
• Geodynamics
• Origin of lakes
• Tropical climates 
• Morphometry, zonations

19
Chapter 11Origin and Ages of Lakes

• Glacial
• Tectonic
• Volcanic
• Riverine
• Coastal
• Solution
• Reservoir

20
(No Transcript)
21
(No Transcript)
22
Tectonic
Lake Tanganyika
Graben lakes multiple faults
23
Rifting A geologic term that describes the
process that occurs when land sinks between two
parallel faults.
24
Kyoga
Albert
Edward
Victoria
Kivu
Tanganyika
Rukwa
25
Lake Chad, which once straddled the borders of
Chad, Niger, Nigeria and Cameroon, has shrunk by
an estimated 95 since the mid 1960s, due to the
growth of agriculture and declining rainfall.
Image Unep
26
Volcanic crater Lakes
27
Caldera lake Laguna Boto
28
Riverine (or fluvial) lakes Oxbow lakes
(billabongs) Blocked-valley lakes Varzea of
floodplain lakes
29
(No Transcript)
30
Lakes with other origins

• Coastal lakes
• Solution (karst) lakes
• Reservoirs

31
(No Transcript)
32
Wintergarden, Florida
33
Kariba Dam on the Zambezi, Zambia/Zimbabwe.
Hydro power, irrigation, flood control, drinking
water supply and now.methane emissions
Reservoirs