Transcript What Is the Open Sea?

Marine Ecosystems
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Marine ecosystems are among the largest of
Earth's aquatic ecosystems. They include
oceans, salt marsh and intertidal ecology,
estuaries and lagoons, mangroves and coral
reefs, the deep sea and the sea floor.
They can be contrasted with freshwater
ecosystems, which have a lower salt content.
Such places are considered ecosystems
because the plant life supports the animal life
and vice-versa.
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Why Should We Care about the Oceans?
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A more accurate name for Earth would be Ocean
because saltwater oceans cover about 71% of the
planet's surface.
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They contain about 250,000 known species of marine
plants and animals and provide many important
ecological and economic services.
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We know more about the surface of the moon than
about the oceans that cover most of the earth.
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According to aquatic scientists, the scientific
investigation of poorly understood marine and
freshwater aquatic systems is a research frontier
whose study could result in immense ecological and
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economic benefits.
Oceans and Seas
Geography of Ocean Basins
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Major Ocean Basins:
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 Pacific is oldest & largest (180 million km )
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 Indian is smallest (75 million km )
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 Atlantic is in between (106 million km )
Depth:
 Average about 4000 m
 Deepest trench is > 10,000 m deep
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Oceanic Circulation
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Properties to consider
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Water Movement
Temperature
Light
Salinity
Nutrients
Oxygen
Human influence
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Deep Blue Sea – Structure
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Littoral Zone (intertidal zone): Shallow
shoreline.
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Neritic Zone: Coast to continental shelf break.
Oceanic Zone: Beyond continental shelf.
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Deep Blue Sea - Structure
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Benthic: Habitat on bottom of ocean.
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Pelagic: Habitat off the bottom of the ocean.
http://www.oceansalive.org/
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Deep Blue Sea - Physical Conditions
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Light
 Approximately 80% of solar energy striking the
ocean is absorbed in first 10 m. None below 600
m, yet oceans are ≈4000 m on average.
Temperature
 Sunlight increases velocity of water.
 Rapid motion decreases density, thus warm
water floats on top of cooler water.
 Thermocline: Layer of water through which
temperature changes rapidly with depth.
 Creates thermal stratification.
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Deep Blue Sea - Chemical Conditions
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Salinity
 In the open ocean, salinity varies from
about 34 ppt to 36.5 ppt.
 Lowest salinity occurs near equator
where precipitation exceeds
evaporation.
 Highest salinity occurs in subtropics
where evaporation exceeds
precipitation.
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Deep Blue Sea - Chemical Conditions
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Oxygen
 A liter of air contains about 200 ml of
oxygen at sea level, while a liter of
seawater contains a maximum of 9 ml of
oxygen.
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http://www.njscuba.net/biology/img/phytoplankton.gif
http://www.njscuba.net/biology/img/zooplankton.gif
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Deep Blue Sea - Human Influences
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For most of human history, vastness of
oceans has acted as a buffer against human
intrusion.
New human-induced threats:
 Overharvesting
 Dumping
 Sediment and Nutrients
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http://www.whalersdiveclub.org/webpages/whalers_photo_gallery.htm13
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Oceans have two major life zones:
the coastal zone and the open sea.
What Is the Coastal Zone?
• The coastal zone is the warm, nutrient-rich, shallow
water that extends form the high-tide mark on land to
the gently sloping,
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the coastal zone makes up less than 10% of the
world's ocean area but contains 90% of all marine
species.
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Low edge of the continental shelf (the submerged part
of the continents). This zone has numerous
interactions with the land and thus human activities
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easily affect it.
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Although it makes up less than a tenth of the
world's ocean area, the coastal zone contains
90% of all marine species
and is the site of most large commercial marine
fisheries.
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Most ecosystems found in the coastal zone
have a high net primary productivity per unit of
area.
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This occurs because of the zone's ample
supplies of sunlight and plant nutrients flowing
from land and distributed by wind and ocean
currents.
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What Is the Open Sea?
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The open ocean consists of a brightly lit surface
layer, a dimly lit middle layer, and a dark bottom
zone.
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The sharp increase in water depth at the edge
of the continental shelf separates the coastal
zone from the vast volume of the ocean called
the open sea.
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Primarily on the basis of the penetration of
sunlight, it is divided into the three vertical
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zones shown in Figure 1
Biological Zones in the Open Sea:
Light Rules
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Euphotic zone: brightly lit surface layer.
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Bathyal zone: dimly lit middle layer.
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Nutrient levels low, dissolved O2
high, photosynthetic activity.
No photosynthetic activity,
zooplankton and fish live there and
migrate to euphotic zone to feed at
night.
Abyssal zone: dark bottom layer.
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Open
Sea
Sea level
Estuarine
Zone
Continental
shelf
Sun
Euphotic Zone
Photosynthesis
High tide Coastal
Zone
Low tide
The Coastal Zone
Abyssal
Zone
Darkness
Bathyal Zone
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Fig. 6-5, p. 130
Estuaries
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fresh _____
water from rivers
An ecosystem where _____
salt
water from the
and streams mixes with _____
_____
ocean.
Estuaries contain plenty of light and nutrients
which support large populations of plants and
animals.
Plants and animals that live in estuaries are able
salinity
to tolerate variations in ________
because the
salt
_____
content of the water varies as the fresh
and salt water mix.
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Estuaries, Salt Marshes, and
Mangrove Forests
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Estuaries are found where rivers meet
the sea.
http://ccmaserver.nos.noaa.gov/images/estuary.jpg
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Estuaries, Salt Marshes, and Mangrove Forests
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Salt Marshes and Mangrove Forests are
concentrated along low-lying coasts.
 Transistion between land and sea
 All driven by ocean tides and river flow.
 Transport organisms, nutrients, oxygen,
and remove wastes.
 Extremely vulnerable to human intrusion.
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Threats to Estuaries
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Estuaries provide harbors, access to the
ocean, and connections to rivers. As a
result, many of the world’s largest cities are
built on estuaries.
Because of this, many estuaries have
become polluted.
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Estuaries
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Coral Reef
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limestone
Coral reefs are __________
islands in the sea that
are built by coral animals called polyps.
Thousands of species of plants and animals live in
the cracks and crevices of coral reefs, making
diverse
coral reefs among the most ________
ecosystems
on Earth.
warm salt water where
Corals can only live in _____
light for photosynthesis.
there is enough ______
Therefore, coral reefs are only found in shallow,
tropical seas.
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Threats to Coral Reefs
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If the water surrounding a reef is too hot or cold, or
if fresh water drains into the water surrounding a
reef, corals have trouble producing limestone.
If the water is too muddy, too polluted, or too high
in nutrients, algae that live within the corals will die
or grow out of control and smother the corals.
Oil spills, sewage, pesticide, and silt runoff have all
been linked to coral reef destruction.
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Coral Reefs
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Polar Ecosystems
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The ice-covered polar caps can be
considered marine ecosystems because
nearly all food is provided by phytoplankton
in the ocean.
North
The ______
Pole is in the Artic Ocean and
South
the ______
Pole is in Antarctica.
Plankton
________
provides the main source of food
at both poles.
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Threats to Polar Ecosystems
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Oil extraction, tourism, and garbage are the
worst threats to the polar ecosystems.
Conservationists want these areas to
become world wildlife refuges.
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Polar Ecosystems
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Polar Ecosystems
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Coral Reefs and Kelp Forests
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Reefs and kelp beds both grow in surface
waters with sufficient light for photosynthesis.
 Both limited by temperature.
Currents deliver oxygen and nutrients, and
remove waste products.
 Biological productivity may depend on
flushing action.
Reefs and kelp beds among most productive
and diverse ecosystems.
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Marine Shores
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Inhabitants of intertidal zone are adapted to
amphibious existence.
 Differential tolerances to periodicity of air
exposure leads to zonation of species.
Due to increased accessibility, intertidal
zones are experiencing increasing human
exploitation.
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Intertidal Zonation
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Mangrove
http://www.stevesbasement.com/mangroveforestA2.jpg
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© 2004 Brooks/Cole – Thomson Learning
Advantages
Physical support from
water buoyancy
Fairly constant
temperature
Nourishment from dissolved
nutrients
Water availability
Easy dispersal of organisms,
larvae, and eggs
Disadvantages
Can tolerate a narrow
range of temperatures
Exposure to dissolved
pollutants
Fluctuating population
size for many species
Dispersion separates
many aquatic offspring
from parents
Less exposure to harmful
UV radiation
Dilution and dispersion of
pollutants
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Factors Limiting Life in Aquatic
Life Zones
1)
2)
3)
4)
Temperature
Access to sunlight
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Euphotic zone
Dissolved oxygen
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5 ppm
Available nutrients
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Shallow water
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upwelling
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0
Limiting
Factors
2,000
O2
1,000
CO2
Depth (feet)
Depth (meters)
500
© 2004 Brooks/Cole – Thomson Learning
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4,000
1,500
6,000
2,000
1.5
90
3.0
4.5
6.0
94
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102
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Concentration of dissolved gas
(parts per million by weight)
O2
7.5
110
CO2
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Natural Capital
Marine Ecosystems
Ecological
Services
Economic
Services
Climate moderation
Food
CO2 absorption
Animal and pet
feed
Nutrient cycling
Waste treatment
Reduced storm impact
(mangroves, barrier
islands, coastal
wetlands)
Habitats and
nursery areas
Genetic resources
and biodiversity
Pharmaceuticals
Harbors and transportation
routes
Coastal habitats for humans
Recreation
Employment
Oil and natural gas
Minerals
Scientific
information
Building materials
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What are estuaries and coastal
wetlands?
Estuary
• Coastal water where seawater mixes
with fresh water and nutrients from
rivers, streams, and runoff
Coastal Wetlands
• Land areas covered with water all or
part of the year
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Estuaries and Coastal Wetlands:
Centers of Productivity
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Estuaries and coastal marshes provide
ecological and economic services.
Filter toxic pollutants, excess
plant nutrients, sediments, and
other pollutants.
 Reduce storm damage by
absorbing waves and storing
excess water produced by storms
and tsunamis.
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Rocky and Sandy Shores:
Living with the Tides
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Organisms experiencing daily low and
high tides have evolved a number of
ways to survive under harsh and
changing conditions.
 Gravitational pull by moon and sun
causes tides.
 Intertidal Zone: area of shoreline
between low and high tides.
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Rocky Shore Beach
Sea star
Hermit crab
Shore crab
High tide
Periwinkle
Sea urchin
Anemone
Mussel
Low tide
Sculpin
Barnacles
Kelp
Sea lettuce
Monterey flatworm
Nudibranch
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Polyps
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Soft bodies
Calcium
carbonate
crust
Zooxanthellae
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Algae
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Color
Food
Oxygen
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Importance of coral reefs
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Removing CO2 from atmosphere
Natural barrier
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Waves and storms
Allows oceans to replenish beach sand
Supports marine life
Source of global fish catch
Provides food, jobs, and building materials
for world’s poorest countries
Supports fishing and tourism
Scientific research
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Gray reef shark
Sea nettle
Green sea
turtle
Producer
to primary
consumer
Fairy basslet
Primary
to secondary
consumer
Blue
tangs
Parrot fish
Sergeant major
Algae
Brittle star
Hard corals
Phytoplankton
Banded coral
shrimp
Coney
Secondary to
higher-level
consumer
Symbiotic
algae
Zooplankton
Blackcap
basslet
Moray
eel
Sponges
Bacteria
All consumers and
producers to
decomposers
Coral Reef
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Ocean warming
Soil erosion
Algae growth from fertilizer runoff
Mangrove destruction
Coral reef bleaching
Rising sea levels
Increased UV exposure from
ozone depletion
Using cyanide and dynamite
to harvest coral reef fish
Coral removal for building material,
aquariums, and jewelry
Damage from anchors, ships,
and tourist divers
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Effects of Human Activities on
Marine Systems: Red Alert
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Human activities
are destroying
or degrading
many ecological
and economic
services
provided by the
world’s coastal
areas.
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