Aquatic Ecology

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Aquatic Ecology
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Factors Affecting Aquatic Ecosystems
Light decreases with depth. - Only 1 of light
below 200 m - No light below 1000 m Turbidity
(cloudiness) affects light. Temperature
decreases with depth due to decreasing energy
input from sun.li
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High tide
Sun
Low tide
Depth in meters
Open Sea
Coastal Zone
Sea level
0
50
Photosynthesis
Euphotic Zone
Estuarine Zone
100
Continental shelf
200
500
Bathyal Zone
Twilight
1,000
1,500
2,000
Abyssal Zone
Water temperature drops rapidly between the
euphotic zone and the abyssal zone in an area
called the thermocline .
3,000
Darkness
4,000
5,000
10,000
0
5
10
15
20
25
30
Water temperature (C)
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Discuss with your table partner
Study the pattern of oxygen with depth. The red
line represents approximately the start of the
aphotic (no light) zone.
What process accounts for the depletion of oxygen
at this depth? Why is the level of oxygen
higher closer to the surface (besides diffusion
of O2 into the H2O)?
Decomposition of organic matter (most of which
comes from above) by aerobic organisms depletes
the oxygen.
Enough light for photosynthesis which adds
oxygen.
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Discuss with your table partner

• Temperature and pressure also affect the levels
  of dissolved oxygen and other gases.
• How does temperature affect the amount of
  dissolved gas?
• How does pressure affect the amount of dissolved
  gas? (Consider what happens when you release the
  pressure on a sealed bottle of soda.)

Temperature varies inversely with maximum DO.

Pressure varies directly with maximum DO. More
dissolved gas at higher pressure.
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Factors Affecting Aquatic Ecosystems
Nutrient availability most limiting
macronutrients are phosphorus (P) Limiting
micronutrients include iron (Fe) essential for
growth of phytoplankton. A failed experiment to
increase the carbon stored in the ocean by
seeding it with iron to stimulate phytoplankton
growth did not work because it also caused a
bloom of toxic diatoms. http//permaculturenews.or
g/2012/11/07/ocean-fertilization-promotes-toxic-al
gae-in-haida-gwaii/
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Discuss with your table partner
Study the pattern of nitrate levels with depth.
What accounts for the increase in nitrates, which
corresponds approximately with the lower levels
of oxygen?
Decomposition of materials (much of which falls
from above) provide available nitrates.
Why are lower levels of nitrates not available
closer to the surface?
Greater rate of uptake of nitrates and other
nutrients. Phytoplankton use up much of the
nitrates.
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Discuss with your table partner

Note that in most locations, the surface has low
levels of nitrates. Relate the areas of higher
nitrates off the west coast of South America to
our weather unit.
How do areas of high nitrates along coast of
South America relate to weather unit?
Location of upwelling that bring nutrient-rich
water from deeper ocean .
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Life zones of the Ocean
Vertical Zones Euphotic Zone 0 - 200
m Greatest amount of light. (Eu good, photo
light) Bathyl Zone 200 - 4500 m Abyssal
Zone 4500 - 11,000 marine snow dead
organisms from above (Abyss the deep) Hadal
Zone gt 6000m
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Benthic Zone Region along bottom of
sea Benthos bottom dwelling sea creature.
Pelagic Zone open sea Region that is not near
the shore or close to the bottom.
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NATURAL CAPITAL
Marine (salt water) Ecosystems
Marine Ecosystems
Economic Services
Ecological Services
Climate moderation
Food
CO2 absorption
Animal and pet feed
Nutrient cycling
Pharmaceuticals
Waste treatment
Harbors and transportation routes
Reduced storm impact (mangroves, barrier islands,
coastal wetlands)
Coastal habitats for humans
Recreation
Habitats and nursery areas
Employment
Oil and natural gas
Genetic resources and biodiversity
Minerals
Scientific information
Building materials
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Estuaries Coastal Wetlands
Estuary where seawater mixes with freshwater
from land, generally at the mouth of a river
Coastal wetland areas of coastal land covered
all or part of the year with salt water Brackish
mix of salt water and fresh

• Importance
• nutrient rich and high primary productivity
• nurseries for fish other aquatic animals
• waterfowl shorebird breeding areas
• filter water pollutants

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Estuaries Coastal Wetlands
Human Impacts

• world has lost over half of its estuaries
  coastal wetlands
• percentage lost in the U.S. even higher. Most
  lost to coastal development
• causes of degradation urban runoff, sewage
  treatment plant effluent, sediment chemical
  runoff from agricultural lands

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Barrier Islands
Barrier Islands long, thin, low offshore islands
of sand that run parallel to the shore. They do
not remain stationary over time.

• Importance
• protect mainland from offshore storms
• shelter inland bays, estuaries, wetlands

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Barrier Islands

• Human Impacts
• Development on barrier islands
• destroys dunes dune
• vegetation
• causes beach erosion
• (through trying to keep
• islands in place)
• destroys or disturbs wildlife habitat (e.g., some
  endangered birds nest on barrier islands)
• Protecting barrier islands
• jetties seawalls
• beach replenishment
• replanting dune vegetation, controlling
  development

Ocean City, MD
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Coral Reefs

• reefs formed by mutualism between polyps algae
• reefs built as colonies of polyps secrete
  limestone hard deposits remain when the polyps
  die
• reefs located in coastal zones of tropical oceans

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Coral Reefs

• Importance
• high biodiversity tropical rain forests of the
  ocean
• protect coastlines from storms high waves
• nurseries for many fish species
• disappearing

• Human Impacts
• sediment runoff effluent
• increased UV radiation (ozone depletion)
• fishing with cyanide dynamite

• Vulnerability
• slow growing
• easily disturbed
• thrive only in clear water

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Mangrove Swamps

• Salt-tolerant trees shrubs
• Warm tropical coastal areas
• Too silty for coral reefs

• Protect coastlines from
• erosion, especially during
• typhoons floods
• Trap nutrient-rich sediments
• Provide habitat for fish, birds,
• invertebrates, and plants

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Freshwater Ecosystems
Lakes Littoral zone shallow area near the shore,
to the depth at which rooted plants stop
growing. Limnetic zone open, sunlit, surface
layer away from the shore. Depth is the limit of
light penetration. Profundal zone deep, open
water where there is no light penetration. Benthic
zone the bottom of a lake inhabited by insect
larvae, decomposers, clams.
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Sunlight
Blue-winged teal
Painted turtle
Green frog
Muskrat
Pond snail
Littoral zone
Plankton
Limnetic zone
Profundal zone
Diving beetle
Northern pike
Benthic zone
Yellow perch
Bloodworms
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NATURAL CAPITAL
Freshwater Systems
Ecological Services
Economic Services
Climate moderation
Food
Nutrient cycling
Drinking water
Waste treatment
Irrigation water
Flood control
Hydroelectricity
Groundwater recharge
Transportation corridors
Habitats for many species
Genetic resources and biodiversity
Recreation
Employment
Scientific information
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Discuss with your table partner
Describe the normal pattern of temperature (and
density) with depth in a lake in the summer. How
does this pattern result in stratification
(layers)?
Upper layer is warmer. Since this warmer layer
is less dense it remains on the top.

• epilimnion warm, upper layer
• epi above
• thermocline zone where temperature changes
  rapidly
• hypolimnion colder, denser lower layer hypo
  below

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Discuss with your table partner
In temperate locations, there is often a turnover
over water in the Spring and Fall, which can help
redistribute nutrients and oxygen. Explain why
these overturns occur.
spring fall (temperate zone lakes)
When the surface water cools in the Fall it
becomes more dense and sinks. In the Spring, as
ice melts it becomes more dense and sinks.
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Video Overturn in Temperate Lakes
http//www.youtube.com/watch?vX26ocQkhNH4
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Atmosphere vs. Bodies of Water

• In the atmosphere, there is more heating at the
  bottom. (Not much blocking of light by the
  atmosphere).
• - This heating at the bottom creates convection
  currents such as the Hadley Cells.
• In bodies of water, most of the heating is at the
  surface since light can not penetrate very far
  into the more dense water.
• - This often leads to thermal stratification.

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Wetlands

• Lands covered with
• Wetland functions
• wildlife habitat, especially for waterfowl
  amphibians
• filter sediments pollutants from runoff ,
  natures kidneys
• flood attenuation
• Human impacts
• some states have lost over 90 of their wetlands
  by filling or draining.