Effects of Human Involvement in the River Ecosystem

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Effects of Human Involvement in the River
Ecosystem

• Jonathan Sexton

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Australia

• Water can be a scarce resource
• Dam rivers to create reservoirs
• 50 of water stored in ten large reservoirs
• Store largest amount of water in reservoirs in
  the world
• Water used for recreation, cities, animals and
  plants

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Tallowa Dam

• Shoalhaven River
• 43m high, 520m long, 50m wide
• Creates a physical barrier

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Tallowa Dam Cont

• Upstream of dam 10 fish species extinct
• Fish not able to utilize spillways
• Competition between species decreased
• Short term answer restock fish

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Problems of Dams

• Fish confined to smaller and different habitats
• Breeding and water condition change
• Food sources and availability change
• Upstream and downstream fish look and behave
  differently

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Change in Population

• Fish accumulate downstream of dam
• More susceptible to predators
• Disease spreads rapidly
• Not able to reproduce at high rates

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Non-Native Species

• Able to gain a foothold
• Can be a new species or old species that was
  present in small numbers
• Once a foothold is gained they are able to move
  into neighboring river systems

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Water Flow

• Water flow is lessened
• Less erosion power
• Allows non-native plants to gain foothold
• Willows in Snowy River floodplain

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Policies

• Water Conservation and Irrigation Commission
• Created in 1971
• Maximize water usage
• Nation Strategy for Ecologically Sustainable
  Development
• Created in 1991
• Gave environment an aliquot of total water
• Aliquot- least amount of water that the
  environment can survive with without damage

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Snowy River

• Hydroelectric dam built in 1974
• Less diversity physically and biologically
• River channels narrow
• Only gets 1 of daily flow
• Restoration plan
• Give the river 27 of yearly flow
• More water in the rainy season

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Murray-Darling Basin

• 14 of total landmass
• Rivers, floodplains and red gum forests
• 20 different species of water birds
• Seasonal flooding has not occurred in many areas
  for years

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Changing the Water Flow

• 2000 entire forest flooded
• Bird populations increased
• Egret species breed for first time since 1975
• Water cap put in place
• Basin needs 40 more water to stabilize

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Indicators

• Amount of water and its condition
• Aquatic plants
• Microscopic organisms
• Fish and Birds

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Water

• Surface area
• Salinity
• Depth of water
• Influences temperature, water chemistry and light
  attenuation

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Aquatic Plants

• Provide shelter and food for mammals, birds, fish
  and bacteria
• Convert CO2 into O2
• Not best indicator
• Cattle grazing nearby can trample and eat
  vegetation

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Microscopic Organisms

• Include free floating bacteria, biofilms,
  zooplankton and fungi
• Bottom of the food chain
• Hydrological factors affect them

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Fish and Birds

• Reproducing
• Abundance
• Birds not best indicator
• Able to fly to new nesting sites
• Able to fly far distances in search of food

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Conclusion

• Humans change the environment drastically
• We are seeing the errors in our ways and now
  trying to fix them
• More expensive to fix