Download QUESTION: Review

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
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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
• Large ships and technology have
destroyed the cod fishery
• Even protected stocks are not
recovering
- Prey may now be competing with,
and eating, young cod
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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
• There are 24 stocks (populations) of
cod
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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
• 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 and less salty) water remains near
the surface
• Temperatures are more stable than land
temperatures
- Water’s high heat capacity
- It takes much more heat to warm water than air
• 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
- Warmed by sunlight and stirred by
wind
- Consistent water density
• Pycnocline = below the surface zone
- Density increases rapidly with
depth
• Deep Zone = below the pycnocline
- Dense, sluggish water
- Unaffected by winds, storms,
sunlight, and temperature
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Ocean water flows horizontally in currents
• Currents = the ocean is composed of vast riverlike
flows
- Driven by density differences, heating and cooling,
gravity, and wind
- Influence global climate and El Niño and La Niña
- 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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The upper waters of the oceans flow in
currents
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Surface winds and heating create vertical
currents
• Upwelling = the vertical flow of cold, deep water towards the
surface
- High primary productivity and lucrative fisheries
- Also occurs where strong winds blow away from, or
parallel to, coastlines
• Downwellings = oxygen-rich water sinks where surface currents
come together
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Seafloor topography can be rugged and
complex
• The seafloor consists of…
- Underwater volcanoes
- Steep canyons
- Mountain range
- The planet’s longest
range is under water
- Mounds of debris
- Trenches
- Some flat areas
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Understanding underwater geography
• Maps show…
- Bathymetry = the measurement of ocean depths
- Topography = the physical geography or the shape
and arrangement of landforms
• Continental shelves = gently sloping areas that underlie
the shallow waters bordering continents
• Shelf-slope break = sudden drop off of the continental
shelf
• Continental slope = connects the continental shelf to the
ocean floor
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A stylized bathymetric 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
• Pelagic = habitats and ecosystems occurring between the
ocean’s surface and floor
• Benthic = 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
- Algae, protists, and
cyanobacteria
• These organisms feed
zooplankton
- Which then feeds fish,
jellyfish, whales, etc.
• Predators at higher trophic levels
include larger fish, sea turtles,
sharks, and fish-eating birds
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Animals of the deep ocean
• 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
• Hydrothermal vents support
tubeworms, shrimp, and other
chemosynthetic species
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Kelp forests harbor many organisms
• Kelp = large, dense, brown algae growing from the floor of
continental shelves
• 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
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Coral reefs are treasure troves of
biodiversity
• Located in shallow subtropical and tropical waters
• Corals = tiny colonial marine organisms
- Related to sea anemones and jellyfish
- Remain attached to rock or existing reef and
capture passing food with stinging tentacles
- Derive nourishment from symbiotic algae,
zooxanthallae
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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
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Deepwater coral reefs exist
• They thrive in waters outside the tropics
- On ocean floor at depths of 200-500 m (650-1650 ft)
• Occur in cold-water areas
• Little is known about these reefs
• Already, many have been badly damaged by trawling
- Some reefs are now being protected
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Intertidal zones 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, barnacles,
urchins, sea slugs, starfish, and
crabs
• Temperature, salinity, and
moisture change dramatically
from high to low tide
- Sandy intertidal zones have
slightly less biodiversity
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Salt marshes 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
- Filter pollution
- Stabilize shorelines against storm surges
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People have changed and destroyed salt
marshes
• People have altered or destroyed salt marshes for
development
- We lose key ecosystem service
- Flooding worsens
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Mangrove forests line coasts
• In tropical and subtropical latitudes
- Replace salt marshes along sandy
coasts
• Mangroves = trees with unique roots
- Curve upwards for oxygen
- 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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Estuaries: 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
• 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 energy from oceans
• Crude oil and natural gas
- Oil spills damage fisheries
• Methane hydrate = a potential
energy source
- Ice-like solid methane
embedded in water crystals
- A vast supply, but research
needs to be done
• Renewable energy sources, such as
waves, tides, heat
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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
• 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
• Plastic items dumped into the
life
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
• Major oils spills (i.e., the Exxon
Valdez) make headlines and cause
serious environmental problems
• Most pollution comes from small
sources
- Boat leakage and runoff from
land
- Naturally occurring leaks from
the seabed
• Oil spills coat and 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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Excess nutrients cause algal blooms
• Harmful algal blooms = nutrients
increase populations of algae that
produce powerful toxins
• Red tide = algal species produce
reddish pigments that discolor water
- Illness and death to wildlife and
humans
- Economic losses to fishing
industries and beach tourism
• Reduce runoff and prevent
consumption of affected organisms
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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
- Even 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
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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 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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Several factors mask declines
• Industrialized fishing has depleted stocks, global
catch has remained stable for the past 20 years
- Fishing fleets travel longer distances to reach lessfished portions of the ocean
- Fleets spend more time fishing and have been
setting out more nets and lines, increasing effort to
catch the same number of fish
- Improved technologies: faster ships, sonar
mapping, satellite navigation, thermal sensing,
aerial spotting
- Data supplied to international monitoring agencies
may be false
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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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Fisheries management
• Based on maximum sustained yield
- Maximal harvest while keeping fish available for the
future
- Managers may limit the harvested or restrict gear used
• Despite management, stocks have plummeted
- It is time to rethink fisheries management
• Ecosystem-based management
- Shift away from species and toward the larger
ecosystem
- Consider the impacts of fishing on habitat and species
interactions
- Set aside areas of oceans free from human interference
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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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Reserves work for both fish and fisheries
• Found that reserves do work as win-win solutions
• Overall benefits included…
- Boosting fish biomass
- Boosting total catch
- Increasing fish size
• Benefits inside reserve boundaries included…
- Rapid and long-term increases in marine organisms
- Decrease mortality and habitat destruction
- Lessen the likelihood of extirpation of species
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Areas outside reserves also benefit
• Benefits included…
- A “spillover effect” when individuals of protected
species spread outside reserves
- Larvae of species protected within reserves “seed the
seas” outside reserves
- Improved fishing and ecotourism
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How should reserves be designed?
• 20-50% of the ocean should be protected in no-take reserves
- How large?
- How many?
- Where?
• Involving fishers is crucial fisheries in coming with these
answers
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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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