Tipe Ekosistem Perairan : Sungai dan Danau

slide tentang Sungai dan Danau

1. Limnology - study of inland waters
Ecology of Freshwater Ecosystems:
Rivers, streams, lakes and wetlands

2. Three basic types of freshwater ecosystems:
•Lotic: rapidly-moving water, for example
streams and rivers.
•Lentic: slow-moving water, including pools,
ponds, and lakes.
•Wetlands: areas where the soil is
saturated or inundated for at least part of
the time.

3. Lotic: Rivers and Streams
•Rivers and streams can be divided along
three dimensions:
–Length: Pools + runs
–Width: Wetted / active channels
–Vertical: Water surface, column
•Riparian zone is a transition area between
the aquatic and upland terrestrial
environments.

4. •Rivers and Streams
•River basin – area of
land drained by river
drainage network
–Separated by
watersheds

5. Dimensions of Stream Structure

6. Flow Rate
•Variation a Function of:
– vegetation/nature of surrounding landscape
•Forests ‘damp out’ variation in flow
–Seasonal variation in ppt.
•Rainy/dry season climate
•Seasonal snow melt
•Impact on flooding
•Flood pulse concept: health of river
system depends on maintaining natural
variations in flow

7. River Continuum Concept
•Organic matter from vegetation adjacent to stream in headwaters
provides nutrient base coarse particulate organic matter
•CPOM  FPOM: provides nutrient base for food web in low
reaches of river
•See: http://www.cotf.edu/ete/modules/waterq/wqcontinuum.html
for more

8. River as a Continuum
•The river continuum concept, first
proposed by Vannote et al 1980,
provides a model of changes that
might take place as water travels
from headwater streams to larger
rivers.
•As stream size increases, the
influence of the surrounding forest
decreases. The river continuum
concept provides predictions of
the way that biological
communities might change from
headwater streams to larger rivers

10. •4 Invert Feeding groups:
•Feeding on bacteria in organic matter of various sizes:
1.Shredders: breakdown CPOM: consume bacteria
2.Filtering and gathering collector: feed on bacteria found in FPOM
3.Grazers: feed on algae on surfaces
4.Gougers: burrow into submerged logs/wood debris

12. Lakes
•Low spot – captures and retains water
•Formation involves geologic processes + dam building by
humans
•Most Freshwater resides in lakes.
–20% in Great Lakes of North America.
–In Indonesia? In Sumatra?

13. Many Types of Lakes - + 11 types
•Glacial lakes
•Tectonic Lakes
•Landslide lakes
•Volcanic lakes
•Shoreline lakes

14. •Littoral zone: Shallows –
light reaches bottom
•Limnetic zone: open
waters –
–Habitat of zooplankton
and nekton (free-
swimming organisms)
•Benthic: primary place
of decomposition

15. •Light
–Lake color depends on light absorption and
biological activity
–Light is increasingly attenuated with water depth
•Temperature
–Lakes become thermally stratified as they warm.
–Temperatures vary seasonally with depth
•Water Movement
–Wind-driven and temperature mixing of the water
column is ecologically important.
•Oxygen can be limiting
–Eutrophic vs. oligotrophic lakes

16. Seasonal Temperature Changes

18. Nutrients and Lakes:
•Oligotrophic:
–Low nutrient availability
–Low surface area to volume ratio
–Low biological production
–well oxygenated
–May have high species diversity
–Generally older lakes
•Eutrophic:
–High biological production
–High nutrient availability – particularly N and K
–High surface area to volume ratio
–may be depleted of oxygen – benthos anaerobic 
methane production
•Dystrophic:
–Acidic, high in organic matter

19. From Schoenherr A.A. 1992. A Natural History of California. University of California Press..

20. Lakes - Human Influences
•Human populations
have had profound,
usually negative effect.
–Municipal and
agricultural run-off 
eutrophication.
–Exotic species - Zebra
Mussels  alter
ecology

21. Dams
•Major dam builders
–Humans
–Beaver
•Damming interrupts both nutrient spiraling and the
river continuum
–Downstream flow is greatly reduced but a constant
inflow is maintained
–The resulting lake develops a heavy bloom of
phytoplankton (or floating plants) due to high nutrient
levels of decaying material on the newly flooded land
–Disrupts seasonal fluctuations in flow
•Lentic-adapted fish (many introduced exotics) replace lotic-
adapted fish
•Pulsed releases of water (hydroelectric dams) can wipe out
or dislodge downstream organisms
•Generally water released from hypolimnon is cold and low in
O
2

22. Succession
•Accumulated sediment  wet meadow
•Nutrients from outside lake  eutrophication

23. •Freshwater wetlands (25.6) = terrestrial
wetlands
•6% of Earth’s surface – declining
•Importance – various reasons
•Various types/degree of wetness
–permanently flooded to periodically saturated soil
•Hydrophytic plants
–Obligate wetland plants require saturated soils
–Facultative wetland plants can grow in either
saturated or upland soil
–Occasional wetland plants are usually found out
of wetland environments but can tolerate wetlands

31. •Wetlands occur in three topographic
situations
–Basin wetlands develop in shallow basins,
from upland depressions to filled-in lakes and
ponds–water flow is vertical
–Riverine wetlands develop along shallow and
periodically flooded banks of rivers–water flow
is unidirectional
–Fringe wetlands occur along the coasts of
large lakes–water flow is in two directions
25.6 Freshwater Wetlands Are a
Diverse Group of Ecosystems

37. Reduced Oxygen Levels and Wetlands as
Biological Filters
•decreased breakdown of organic matter
•Wetlands = nutrient sinks
–Nutrient sink = environment that traps
nutrients
•Nutrient source = net release of nutrients – results
as oxygen is introduced
•Biological filter: remove potentially
damaging chemicals from waterways

38. Hydrologic Regulators
•Act as hydrologic buffers
–Water amounts entering may vary
•Excess water absorbed and retained
–Water amount leaving remains constant
•Impact:
–Water may percolate into aquifers
–Prevent down stream flooding
•Prevent damage
•Reduce leaching of nutrients

39. •The loss of wetlands has reached a point
where both environmental and
socioeconomic values are in jeopardy
–Waterfowl habitat
–Groundwater supply and quality
–Floodwater storage
–Sediment trapping
Ecological Issues: The
Continuing Decline of Wetlands

42. •Wetland Protection
•Endangered Species Act
•Clean Water Act of 1972 – section 404
•EPA
•State Laws
–California Coastal Commission
–Other:
http://ceres.ca.gov/wetlands/introduction/defining_wetl
ands.html
–http://biology.kenyon.edu/fennessy/AMN%20Wetland
%20Webpage/Comps%20Webpage/thebroadperspec
tive.htm