Wetlands, Lakes and Streams

Based on Mader, Sylvia S. 1996. Biology - 5th Ed. WCB

and

Cox, G.W. 1997. Conservation Biology - 2nd ed. WCB

and

Levine, J.S. and K.R. Miller. 1994. Biology: Discovering Life. D.C. Heath

 

Reading: Chapters 15, 16 in Cox – pp. 55-57 in Levine and Miller

 

Aquatic Communities

Freshwater

  1. lakes (lentic)
    1. Know Figure 3.5 (review)
  2. rivers and streams (lotic)

Marine

Figure 3.35 p60

nearshore

  1. estuary
  2. rocky shore
  3. sandy beach
  4. coral reef

offshore

  1. pelagic
  2. benthic

Wetlands

  1. transitional between aquatic and terrestrial ecosystems
  2. often covered by water at least part of the year
  3. plant community has many hydrophilic species

examples:

  1. marshes - dominated by grasses
  2. bogs - acidic, carnivorous plants, fewer grasses
  3. fens - alkaline waters
  4. salt marshes - mostly grasses
    1. often in estuaries
    2. grade into mud flats
    3. intermediate salt contents, high nutrient levels
  5. swamps - dominated by woody plants
  6. mangrove swamps
  7. hardwood bottomland forests
  8. prairie potholes
  9. vernal pools

wetlands occupy 6% of Earth’s surface

  1. high productivity
    1. water
    2. lots of light
    3. nutrients
  2. refuge and breeding ground for migratory birds
  3. lots of invertebrates, fish, frogs, etc.
  4. high activity during wet season

Wetland destruction

often drained:

  1. agriculture
  2. reduce disease
  3. urban sprawl (cities located near water)
  4. filled on floodplains (Marietta)
  5. canals (oil exploration in Mississippi delta)

useful:

  1. absorbing floods
  2. reduce erosion
  3. groundwater recharge
  4. filtering wastes
  5. wildlife habitat
  6. breeding ground
  7. commercial products:
    1. cranberries, blueberries, blackberries, rice, peat moss

threats:

  1. agriculture
  2. pollution
  3. dams
    1. flood wetlands
    2. prevent silt from accumulating at delta
  4. dumps
  5. levees - prevents seasonal filling
  6. up to 1/2 of wetlands in lower 48 states destroyed
  7. only 10% of Ohio wetlands remain

legislation

  1. the 1972 Clean Water Act - protects coastal wetlands
  2. Emergency Wetlands Resources Act - 1986 -designate and acquire critical wetlands
  3. Wetlands reserve program - reclaim farmland as wetlands
  4. Bush administration - narrowed definition of wetlands, excluding many (1/3) from protection

 

Eutrophication:

Nutrient Levels

  1. Low nutrient levels – oligotrophic
  2. High nutrient levels – eutrophic

Movement from oligotrophic to eutrophic is natural, but slow

Humans accelerate movement - eutrophication

Causes of Eutrophication

  1. Sewage
  2. Fertilizer runoff & contamination of groundwater
  3. Soil erosion
  4. Phosphorous principle problem in freshwater

Problems posed by eutrophication

  1. Algal blooms
    1. Taste, odor
    2. Shade out tracheophytes
    3. Deplete O2 levels at night
  2. Change in species composition of lakes
  3. Problems exacerbated by stratification, particularly in hypolimnion

 

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