Download Ch. 16 Marine and Coastal Systems

Ch 16
Marine and Coastal
Systems: Resources,
Impacts, and Conservation
Part 2: Environmental Issues
the Search for Solutions
PowerPoint® Slides prepared by
Jay Withgott and Heidi Marcum
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
This lecture will help you understand:
• The marine environment
• Major marine ecosystems
• Human uses of marine
resources
• Human impacts on the
marine environment
• The state of ocean
fisheries
• Marine protected areas
and reserves
Schooling Marine fish
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Central Case: collapse of the cod fisheries
• No fish has more impact on
human civilization than the
Atlantic cod
• Eastern Canadians and U.S.
fishermen have fished for cod
for centuries since in early
1500s
• Large ships and technology
have destroyed the cod fishery
(Trawling in particular)
• Even protected stocks are not
recovering
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Massachusetts cod fishermen
haul in a dwindling catch
Cod are groundfish
• They live or feed along
the bottom
- Halibut, pollock,
flounder
• Cod eat small fish and
invertebrates
• They grow to 60-70 cm
long and can live 20 years
• Inhabit cool waters on
both sides of the Atlantic
Dwindles in 1980s - Trawling (p459)
destroyed underground habitats
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There are 24 stocks
(populations) of cod
Oceans cover most of the Earth’s surface
• The oceans influence global climate, team with
biodiversity, facilitate transportation and commerce,
and provide resources for us
• They cover 71% of Earth’s surface and contain 97%
of Earth’s surface water – Major Hydrosphere
• Oceans influence the atmosphere, lithosphere, and
biosphere
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The oceans contain more than water
• Ocean water is 96.5%
water
- Plus, ions of
dissolved salts
• Evaporation removes
pure water and leaves a
higher concentration of
salt
• Nutrients (nitrogen and
phosphorus)
• Dissolved gas: Oxygen
is added by plants,
bacteria, and
atmospheric diffusion
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Ocean water is vertically structured
• Temperature declines with depth
• Heavier (colder & saltier) water sinks
- Light (warmer & less salty) water remains near the
surface
• Temperatures are more stable than land temperatures
- Water’s much higher heat capacity than land or air
It takes much more heat to warm water than air (~4x )
(i.e., larger specific heat: 1 cal/(oC g)=4.184J/(K g) )
• Oceans regulate the earth’s climate
- They absorb and release heat
- Ocean’s surface circulation
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The ocean has several layers
• Surface zone (~150 m): ~2%
- Warmed by sunlight and
stirred by wind, Consistent
water density
• Pycnocline(~1,000m): ~18%
below the surface zone
- Density increases rapidly
with depth
• Deep Zone: ~ 80%
below the pycnocline
- Dense, sluggish water
- Unaffected by winds, storms,
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Ocean water flows horizontally in currents
Convection
• Currents: the ocean is composed of vast riverlike flows
- Driven by density differences, heating and cooling,
gravity (Tide), and wind
- Influence global climate
- Transport heat, nutrients, pollution, and the larvae of
many marine species
• Some currents such as the Gulf Stream are rapid and
powerful
- The warm water moderates Europe’s climate
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Ocean Currents : A Big Picture
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The upper waters of the oceans flow in currents
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Surface winds and heating create vertical currents
• Upwelling: where surface current diverge, the vertical flow
of cold, deep water towards the surface
- Rich in nutrient from bottom, thus giving high primary
productivity and lucrative fisheries
- Also occurs where strong winds blow away from, or
parallel to, coastlines
• Downwellings: where surface currents come together
(converge), oxygen-rich surface water sinks
- transport warm water
rich in gas (O2) for
deep-water life.
Start (11/20/08)
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Seafloor topography can be rugged and complex
• The seafloor consists of…
- Underwater volcanoes
- Steep canyons, trenches
- Mountain range
- The planet’s longest
range is under water
- Mounds of debris
Diverging Mid-Atlantic Ridge:
N/S Amarican Plate and African Plate
(Cf. p200)
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- Some flat areas
Profile of the ocean
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Regions of ocean differ greatly
• Some zones support more life than others
• Photic Zone: well-lighted top layer that supports high
primary productivity
(~ limnetic zone of a lake)
• Pelagic Zone : habitats and ecosystems occurring
between the ocean’s surface and floor
(~ profundal zone of a lake)
• Benthic Zone : habitats and ecosystems occurring on
the ocean floor
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Open ocean systems vary in biodiversity
• Microscopic phytoplankton
constitute the base of the
marine food chain in the
pelagic zone: Producers
- Algae, cyanobacteria
and protists
• These organisms feed
zooplankton (Primary
Consumer)
- Which then feeds fish,
jellyfish, whales, etc.
(Secondary Consumers)
• Predators at higher trophic
levels include larger fish, sea
turtles, sharks, and fish-eating
birds (Tertiary Consumer)
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Marine Ecosystems:
• Kelp Forest Ecosystem :
• Deep Ocean Ecosystem :
• Coral Reef Ecosystem :
Coastal Ecosystems:
• Intertidal (Littoral) Ecosystem :
• Salt Marsh Ecosystem :
• Mangrove Forest Ecosystem :
• Estuary Ecosystem :
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Kelp forests: Underwater Forests
harbor many organisms:
• Kelp: (~60 m) large, dense,
brown algae growing from the
floor of continental shelves
(Cf.: Giant Sequoia ~ 80m)
• Dense strands form kelp forests
along temperate coasts
• Shelter and food for organisms
• Absorbs wave energy and
protects shorelines from erosion
• Eaten by people
• Alginates serve as thickeners in
cosmetics, paints, paper, and
soaps
→ The Keystone species ?
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Deep Ocean Ecosystem:
• Animals adapt to extreme water
pressure and the absence of light
- Scavenge carcasses or organic
detritus
- Some are predators, while others
have mutualistic relationships with
bacteria
- Some species carry bacteria that
produce light chemically by
bioluminescence (What’s the
common example in land?)
Anglerfish lures prey with a
glowing organ
• Hydrothermal vents support
tubeworms, shrimp, and other
chemosynthetic species
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(The Black Smoker, p104, Fig. 4.18)
Coral reefs are treasure troves of biodiversity
• Located in shallow subtropical and tropical waters
needs warm, clean pollution free, O2 rich water
• Corals: tiny colonial marine organisms (animal)
- Related to sea anemones and jellyfish
- Remain attached to rock or existing reef and capture
passing food with stinging tentacles
- Derive nourishment from symbiotic photosynthetic
brown algae, zooxanthallae
- Extract CO2 ( in a form of CO32-) from sea water to
build reef limestone (CaCO3)
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Coral reefs are treasure troves of biodiversity
• Corals: tiny colonial
marine organisms
(animal)
- Related to sea
anemones and
jellyfish
- Remain attached
to rock or existing
reef and capture
passing food with
stinging tentacles
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Coral reefs consist of millions of corals
• Coral reef: a mass of calcium
carbonate composed of the
skeletons of corals
- Consists of millions of densely
packed individuals
- Protect shorelines by absorbing
waves
- Innumerable invertebrates and
fish species find food and
shelter in reef nooks and
crannies
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Coral reefs are in worldwide decline
• Coral bleaching: occurs when zooxanthellae leave the coral
- Coral lose their color and die, leaving white patches
- From climate change, pollution, or unknown natural causes
• Nutrient pollution causes algal growth, which covers coral
• Divers damage reefs by using cyanide to capture fish
• Acidification of oceans deprives corals of necessary carbonate
ions for their structural parts
• Limestone becomes part of
lithosphere storage of C (or
CO2 )
• Destruction of coral will cause
more CO2 in the atmosphere
End (11/20/08)
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Intertidal Zones Ecosystem undergo constant change
• Intertidal (littoral) ecosystems : where the ocean meets
the land
- between the uppermost reach of the high tide and the
lowest limit of the low tide
• Tides: periodic rising and falling of the ocean’s height
due to the gravitational pull of the sun and moon
- Intertidal organisms spend part of their time
submerged in water and part of their time exposed to
sun and wind
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A typical intertidal zone
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Intertidal zones are a tough place to live
• But they have remarkable
diversity
- Rocky shorelines, crevices,
pools of water (tide pools)
- Anemones, mussels, crabs
barnacles, urchins, sea slugs,
and, starfish
• Temperature, salinity, and
moisture change dramatically
from high to low tide
- Sandy intertidal zones have
slightly less biodiversity
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Salt Marsh Ecosystems occur widely
• Salt marsh: occur along coasts at temperate latitude
- Tides wash over gently sloping, sandy, silty
substrates
- High primary productivity
- Critical habitat for birds and commercial fish and
shellfish species
- Like any wetlands, Filter pollution
- Stabilize shorelines against storm surges
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People have changed and destroyed salt marshes
for development
- We lose key ecosystem service
- Flooding worsens
Tidal Creeks and Benches
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Mangrove Forests Ecosystem: line coasts
• In tropical and subtropical
altitudes, these tropical
evergreen replace salt marshes
along sandy coasts
• Mangroves: trees w/ unique
roots
- Curve upwards for O2
- Curve downwards for
support
• Nurseries for commercial fish
and shellfish
• Nesting areas for birds
• Food, medicine, tools,
construction materials
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Mangrove forests have been destroyed
• Development for residential, commercial, and
recreational uses
• Shrimp farming
• Half the world’s mangrove forests are gone
• Once destroyed, coastal areas no longer
- Slow runoff
- Filter pollutants
- Retain soil
- Protect communities against storm surges
• We are protecting only 1% of remaining mangroves
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Estuary Ecosystems: where fresh and salt water meet
• Estuaries: water bodies where rivers flow into the ocean
- Wide fluctuations in salinity
• Critical habitat for shorebirds and shellfish
• Transitional zone for anadromous (spawn in freshwater,
mature in salt water) fishes (example?)
• Affected by development, pollution, habitat alteration,
and overfishing
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Oceans provide transportation routes
• Humans have interacted with oceans for thousands of
years
- Moving people and products over vast distances
- Accelerated global reach of cultures
• Has substantial impact on the environment
- Moves resources around the world
- Ballast water transplants organisms, which may
become invasive
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We extract minerals from oceans
• Minerals such as sand, gravel, sulfur, calcium carbonate,
and silica
• Rich deposits of copper, zinc, silver, and gold
• Magnesium: dissolved (Mg2+ , third most ions)
H2O(l) + CaO(s) → Ca2+(aq) + 2OH-(aq)
Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s)
Mg(OH)2(s) +2HCl(aq) → MgCl2(aq) + 2H2O(l)
MgCl2(aq) → MgCl2(s) → MgCl2(l) → Mg(s) + Cl2(g)
evaporate H2O
melt
Electrolyze
• Manganese nodules are scattered along the ocean’s floor
- But, they are too hard to currently mine
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Marine pollution threatens resources
• Even into the mid-20th century, coastal U.S. cities
dumped trash and untreated sewage along their shores
• Oil, plastic, chemicals, excess nutrients make their way
from land into oceans
• Raw sewage and trash from cruise ships
• Abandoned fishing gear from fishing boats
In 2006, 359,000 Ocean Conservancy volunteers from 66 nations
picked up 3.2 million kg (7 million lbs.) of trash
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Nets and plastic debris endangers marine life
• Plastic items dumped into the
sea harm or kill wildlife
• Plastic is non-biodegradable
- Drifts for decades
- Washes up on beaches
- Wildlife eat it or get
entangled and die
• Marine debris affects people
- Equipment damage
• The 2006 Marine Debris
Research, Prevention and
Reduction Act
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Oil pollution comes from spills of all sizes
causing serious environmental problems
• Major oils spills make headlines
1989 March 24, 1989; 11 M gal
the Exxon Valdez hit a reef
2010, April 20th : 200 M gal
the BP Offshore Station Explode
• Most pollution comes from
small sources, such as Boat
leakage & runoff from land
Naturally occurring leaks from
the seabed
• Oil spills coat & poison wildlife
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Oil pollution has decreased
• Governments have implemented
more stringent regulations
• The U.S. Oil Pollution Act of 1990
- Creates a $1 billion prevention
and cleanup fund
- Requires all ships have double
hulls by 2015
• Recently, oil spills have decreased
- The oil industry resists such
safeguards
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Toxic pollutants contaminate seafood
• Mercury contamination
- From coal combustion and other sources
- Bioaccumulates and biomagnifies
- Dangerous to young children and pregnant or nursing
mothers
- Avoid eating swordfish, shark, and albacore tuna
- Eat seafood low in mercury (catfish, salmon, canned
light tuna)
• Avoid seafood from areas where health advisories have
been issued
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Emptying the oceans
• We are placing unprecedented pressure on marine
resources
- Half the world’s marine fish populations are fully
exploited
- 25% of fish population are overexploited and
heading to extinction
• Total fisheries catch leveled off after 1998, despite
increased fishing effort
- It is predicted that populations of all ocean species
we fish for today will collapse by the year 2048
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The total global fisheries catch has increased
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We have long overfished
• People began depleting sea life centuries ago
• Some species hunted to extinction: Steller’s sea cow,
Atlantic gray whale, Caribbean monk seal
• Overharvesting of Chesapeake Bay oyster beds led to
the collapse of its fishery, eutrophication, and
hypoxia
• Decreased sea turtle populations causes overgrowth
of sea grass and can cause sea grass wasting disease
• People never imagined that groundfish could be
depleted
- New approaches or technologies increased catch
rates
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Fishing has industrialized
Factory Fishing : highly industrialized, huge vessels use powerful
technologies to capture fish in huge volumes
- process and freeze their catches while at sea
• Driftnets for schools of herring, sardines, mackerel, sharks
• Longline fishing for tuna and swordfish
• Trawling for pelagic fish and groundfish
→devastate deep ocean ecosystem
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Fishing practices kill nontarget animals
• By-catch: the accidental capture of
animals
• Driftnetting drowns dolphins, turtles, and
seals
- Fish die from air exposure on deck
- Banned or restricted by many nations
• Longline fishing kills turtles, sharks, and
albatrosses
- 300,000 seabirds die each year
• Bottom-trawling destroys communities
- Likened to clear-cutting and strip
mining
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Modern fishing fleets deplete marine life rapidly
• Grand Banks (p444) cod have been fished for centuries
• Catches more than doubled with immense industrial
trawlers
- Record-high catches lasted only 10 years
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Industrialized fishing depletes populations
• Catch rates drop precipitously with industrialized
fishing
- 90% of large-bodied fish and sharks are eliminated
within 10 years
- Populations stabilize at 10% of their former levels
• Marine communities may have been very different
before industrial fishing
- Removing animals at higher trophic levels allows
prey to proliferate and change communities
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Oceans today contain only one-tenth of the large-bodied
animals they once did
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We are “fishing down the food chain”
• Figures on total global catch do not relate the species,
age, and size of fish harvested
• As fishing increases, the size and age of fish caught
decline
- 10-year-old cod, once common, are now rare
• As species become too rare to fish, fleets target other
species
- Shifting from large, desirable species to smaller, less
desirable ones
- Entails catching species at lower trophic levels
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Consumer choices influence fishing practices
• Buy ecolabeled seafood
- Dolphin-safe tuna
• Consumers don’t know how their
seafood was caught
- Nonprofit organizations have
devised guides for consumers
- Best choices: farmed catfish and
caviar, sardines, Canadian snow crab
- Avoid: Atlantic cod, wild-caught
caviar, sharks, farmed salmon
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We can protect areas in the ocean
• Marine protected areas (MPAs) : established along the
coastlines of developed countries
- Still allow fishing or other extractive activities
• Marine reserves : areas where fishing is prohibited
- Leave ecosystems intact, without human interference
- Improve fisheries, because young fish will disperse
into surrounding areas
• Many commercial, recreation fishers, and businesses do
not support reserves
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Conclusion
• Oceans cover most of our planet and contain diverse
topography and ecosystems
• We are learning about the oceans and coastal
environments, intensifying our use their resources
and causing severe impacts
• Setting aside protected areas of the ocean can serve to
maintain natural systems and enhance fisheries
• We may once again attain the ecological systems that
once flourished in our waters
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QUESTION: Review
An “upwelling” is defined as….
a) The vertical flow of cold, deep water towards the
surface
b) The vertical flow of warm, deep water towards the
surface
c) The vertical flow of cold, shallow water towards the
bottom
d) The vertical flow of warm, deep water towards the
bottom
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QUESTION: Review
The area of an ocean that contains open water that
receives sunlight is called the _______zone.
a)
b)
c)
d)
Littoral
Photic
Pelagic
Benthic
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QUESTION: Review
_____ is defined as “large, dense, brown algae growing
from the floor of continental shelves.”
a)
b)
c)
d)
Coral
Red tide
Bottomfish
Kelp
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QUESTION: Review
Coral bleaching occurs when ….
a)
b)
c)
d)
Corals reproduce
Fish move into coral reefs
Zooxanthellae leave the coral
Coral reefs expand their range
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QUESTION: Review
An area where rivers flow into the ocean is called a(n) …?
a)
b)
c)
d)
Estuary
Mangrove swamp
Salt marsh
Coral reef
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QUESTION: Review
Which of the following does not mask the decline of
fisheries?
a)
b)
c)
d)
Fishing fleets travel longer distances
Fishing fleets spend more time fishing
Fishing fleets use traditional methods of fishing
Data supplied to monitoring agencies may be false
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QUESTION: Review
Marine reserves have all the following benefits except:
a)
b)
c)
d)
Fishing increases in the reserve
The size of fish increases
Larvae can “seed” areas outside the reserve
Decreased mortality and habitat destruction
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QUESTION: Interpreting Graphs and Data
What does this graph show about the future of global
fisheries catch?
a) China will be a major
player in applying fishing
pressure
b) China will be player a
smaller role in applying
fishing pressure
c) The world will decrease its
fishing pressure
d) The U.S. is not included in
this graph
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QUESTION: Interpreting Graphs and Data
Which conclusion can you draw from this graph?
a) Oceans today contain far
fewer fish
b) Oceans today contain far
more fish
c) It is easier to find fish today
d) There is little correlation
between fishing and fish
stocks
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QUESTION: Viewpoints
If a developer wants to build a community on an
estuary, providing jobs but eliminating the marsh,
what should be done?
a) Let the developer build; we need the jobs
b) Let the developer build, but make him/her pay
for any damage from storms
c) Let the surrounding landowners vote whether
to let the developer build
d) Prevent the development; the potential
damage is too great
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QUESTION: Viewpoints
Do you plan to alter your decisions about eating
seafood?
a) Yes; I will be more selective about what I eat
b) No; I will continue to eat the same type and
amount of seafood as always
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