Aquatic Ecology Notes

1
Aquatic Ecology Notes
2
Chapter Overview Questions

• What are the basic types of aquatic life zones
  and what factors influence the kinds of life they
  contain?
• What are the major types of freshwater life
  zones, and how do human activities affect them?

3
Chapter Overview Questions

• What do we know about aquatic biodiversity, and
  what is its economic and ecological importance?
• How are human activities affecting aquatic
  biodiversity?
• How can we manage and sustain the worlds marine
  fisheries?

4
Chapter Overview Questions (contd)

• How can we protect, sustain, and restore
  wetlands?
• How can we protect, sustain, and restore lakes,
  rivers, and freshwater fisheries?

5
Chapter Overview Questions

• Why is water so important, how much freshwater is
  available to us, and how much of it are we using?
• What causes freshwater shortages, and what can be
  done about this problem?
• What are the advantages and disadvantages of
  withdrawing groundwater?
• What are the advantages and disadvantages of
  using dams and reservoirs to supply more water?

6
Chapter Overview Questions (contd)

• What are the advantages and disadvantages of
  transferring large amounts of water from one
  place to another?
• Can removing salt from seawater solve our water
  supply problems?
• How can we waste less water?
• How can we use the earths water more
  sustainably?
• What causes flooding, and what can we do about it?

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WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL

• Water keeps us alive, moderates climate, sculpts
  the land, removes and dilutes wastes and
  pollutants, and moves continually through the
  hydrologic cycle.
• Only about 0.02 of the earths water supply is
  available to us as liquid freshwater.

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WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL

• Comparison of population sizes and shares of the
  worlds freshwater among the continents.

Figure 14-2
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WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL

• Some precipitation infiltrates the ground and is
  stored in soil and rock (groundwater).
• Water that does not sink into the ground or
  evaporate into the air runs off (surface runoff)
  into bodies of water.
• The land from which the surface water drains into
  a body of water is called its watershed or
  drainage basin.

10

Unconfined Aquifer Recharge Area
Evaporation and transpiration
Evaporation
Precipitation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Water table
Infiltration
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308
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WATERS IMPORTANCE, AVAILABILITY, AND RENEWAL

• We currently use more than half of the worlds
  reliable runoff of surface water and could be
  using 70-90 by 2025.
• About 70 of the water we withdraw from rivers,
  lakes, and aquifers is not returned to these
  sources.
• Irrigation is the biggest user of water (70),
  followed by industries (20) and cities and
  residences (10).

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Salinity

• The saltiness.

13
Niches
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What Kinds of Organisms Live in Aquatic Life
Zones?

• Aquatic systems contain floating, drifting,
  swimming, bottom-dwelling, and decomposer
  organisms.
• Plankton important group of weakly swimming,
  free-floating biota.
• Phytoplankton (plant), Zooplankton (animal),
  Ultraplankton (photosynthetic bacteria)
• Necton fish, turtles, whales.
• Benthos bottom dwellers (barnacles, oysters).
• Decomposers breakdown organic compounds (mostly
  bacteria).

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Phytoplankton

• Description small drifting plants
• Niche they are producers that support most
  aquatic food chains
• Example cyanobacteria many types of algae

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Zooplankton

• Description herbivores that feed on
  phytoplankton or other zooplankton
• Niche food stock for larger consumers
• Example krill small crustaceans

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Nekton

• Description larger, strong-swimming consumers
• Niche top consumers in the aquatic ecosystem
• Example fish, turtles, and whales

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Benthos

• Description bottom-dwelling creatures
• Niche primary consumers, decomposers
• Example barnacles, oysters, and lobsters

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Freshwater Ecosystems
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FRESHWATER LIFE ZONES

• Freshwater life zones include
• Standing (lentic) water such as lakes, ponds, and
  inland wetlands.
• Flowing (lotic) systems such as streams and
  rivers.

Figure 6-14
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Flowing Water Ecosystems

• Because of different environmental conditions in
  each zone, a river is a system of different
  ecosystems.

22
Natural Capital
Ecological Services of Rivers

• Deliver nutrients to sea to help sustain
  coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and renourish wetlands
• Provide habitats for wildlife

Fig. 12-11, p. 267
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Freshwater Streams and RiversFrom the Mountains
to the Oceans

• Water flowing from mountains to the sea creates
  different aquatic conditions and habitats.

Figure 6-17
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Headwater Stream Characteristics

• A narrow zone of cold, clear water that rushes
  over waterfalls and rapids. Large amounts of
  oxygen are present. Fish are also present. Ex.
  trout.

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Downstream Characteristics

• Slower-moving water, less oxygen, warmer
  temperatures, and lots of algae and
  cyanobacteria.

26
Energy Source

• Gravity

27
Standing Water Ecosystems

• Lakes, ponds, etc.

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Life in Layers

• Life in most aquatic systems is found in surface,
  middle, and bottom layers.
• Temperature, access to sunlight for
  photosynthesis, dissolved oxygen content,
  nutrient availability changes with depth.
• Euphotic zone (upper layer in deep water
  habitats) sunlight can penetrate.

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Lakes Water-Filled Depressions

• Lakes are large natural bodies of standing
  freshwater formed from precipitation, runoff, and
  groundwater seepage consisting of
• Littoral zone (near shore, shallow, with rooted
  plants).
• Limnetic zone (open, offshore area, sunlit).
• Profundal zone (deep, open water, too dark for
  photosynthesis).
• Benthic zone (bottom of lake, nourished by dead
  matter).

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Littoral Zone

• A shallow area near the shore, to the depth at
  which rooted plants stop growing. Ex. frogs,
  snails, insects, fish, cattails, and water lilies.

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Limnetic Zone

• Open, sunlit water that extends to the depth
  penetrated by sunlight.

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Profundal Zone

• Deep, open water where it is too dark for
  photosynthesis.

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Thermal Stratification
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Lakes Water-Filled Depressions
Figure 6-15
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Definition

• The temperature difference in deep lakes where
  there are warm summers and cold winters.

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Lakes Water-Filled Depressions

• During summer and winter in deep temperate zone
  lakes the become stratified into temperature
  layers and will overturn.
• This equalizes the temperature at all depths.
• Oxygen is brought from the surface to the lake
  bottom and nutrients from the bottom are brought
  to the top.

37
Causes

• During the summer, lakes become stratified into
  different temperature layers that resist mixing
  because summer sunlight warms surface waters,
  making them less dense.

38
Thermocline

• The middle layer that acts as a barrier to the
  transfer of nutrients and dissolved oxygen.

39
Fall Turnover

• As the temperatures begin to drop, the surface
  layer becomes more dense, and it sinks to the
  bottom. This mixing brings nutrients from the
  bottom up to the surface and sends oxygen to the
  bottom.

40
Spring Turnover

• As top water warms and ice melts, it sinks
  through and below the cooler, less dense water,
  sending oxygen down and nutrients up.

41
Freshwater Wetlands
42
Freshwater Inland Wetlands Vital Sponges

• Inland wetlands act like natural sponges that
  absorb and store excess water from storms and
  provide a variety of wildlife habitats.

Figure 6-18
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Freshwater Inland Wetlands Vital Sponges

• Filter and degrade pollutants.
• Reduce flooding and erosion by absorbing slowly
  releasing overflows.
• Help replenish stream flows during dry periods.
• Help recharge ground aquifers.
• Provide economic resources and recreation.

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Marshes

• An area of temporarily flooded, often silty land
  beside a river or lake.

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Swamps

• A lowland region permanently covered with water.

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Hardwood Bottomland Forest

• An area down by a river or stream where lots of
  hardwoods, like oaks, grow.

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Prairie Potholes

• These are depressions that hold water out on the
  prairie, especially up north in Canada. It is a
  very good duck habitat.

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Peat Moss Bog

• A wet area that over time fills in (the last
  stage of succession is peat moss). It can be
  very deep. In Ireland, they burn this for wood.

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Importance of freshwater wetlands

• They filter purify water.
• Habitat for many animals and plants.

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Historical Aspects

• Developers and farmers want Congress to revise
  the definition of wetlands. This would make
  60-75 of all wetlands unavailable for
  protection. The Audubon Society estimates that
  wetlands provide water quality protection worth
  1.6 billion per year, and they say if that
  wetlands are destroyed, the U.S. would spend 7.7
  billion to 31 billion per year in additional
  flood-control costs.

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Estuaries
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Definition

• A partially enclosed area of coastal water where
  sea water mixes with freshwater.

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Salt Marshes

• The ground here is saturated with water and there
  is little oxygen, so decay takes place slowly.
  It has a surface inlet and outlet, and contains
  many invertebrates. It is also the breeding
  ground for many ocean animals. Ex. crabs and
  shellfish.

54
Mangrove Forests

• These are along warm, tropical coasts where there
  is too much silt for coral reefs to grow. It is
  dominated by salt-tolerant trees called mangroves
  (55 different species exist). It also helps to
  protect the coastline from erosion and provides a
  breeding nursery for some 2000 species of fish,
  invertebrates, and plants.

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Importance of Estuaries

• Just one acre of estuary provides 75,000 worth
  of free waste treatment, and has a value of about
  83,000 when recreation and fish for food are
  included.
• Prime Kansas farmland has a top value of 1,200
  and an annual production value of 600.

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The Everglades

• Southern Florida to the Keys

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Case Study Restoring the Florida Everglades

• The worlds largest ecological restoration
  project involves trying to undo some of the
  damage inflicted on the Everglades by human
  activities.
• 90 of parks wading birds have vanished.
• Other vertebrate populations down 75-95.
• Large volumes of water that once flowed through
  the park have been diverted for crops and cities.
• Runoff has caused noxious algal blooms.

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Problems

• As Miami develops, it encroaches on everglades.
  Plus, it prompts people vs. wildlife. It is
  freshwater and local areas are draining it.

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Restoring the Florida Everglades

• The project has been attempting to restore the
  Everglades and Florida water supplies.

Figure 12-10
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Restoration

• Build huge aqueduct, or find other sources of
  fresh water an protect it federally under
  endangered species act, etc.

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The Water Resource
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Importance

• Leonardo da Vinci said that Water is the driver
  of nature. Without water, the other nutrient
  cycles would not exist in their present forms,
  and current forms of life on earth could not
  exist.

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Hydrogen Bonds
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Attraction Between Molecules

• The strong forces of attraction between molecules
  of water.

65
Heat Capacity

• Water changes temp very slowly because it can
  store heat. This protects living organisms from
  the shock of abrupt temperature changes.

66
Heat of Vaporization

• The temperature at which water turns to vapor.

67
Universal Solvent

• Water can dissolve a wide variety of compounds.
  This means it can easily become polluted by
  water-soluble wastes.

68
Expansion When Frozen

• Ice has a lower density than liquid water. Thus,
  ice floats on water.