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13
Marine and Coastal
Systems and Fisheries
PowerPoint® Slides prepared by Stephen Turnbul
Copyright © 2013 Pearson Canada Inc.
© 2010 Pearson Education Canada
13-1
Housekeeping Items
• We talked about mining last week. Some Chinese state companies
are now making plans to conduct mining operations on the moon
(countries are forbidden to do so), and other companies are looking
at mining asteroids.
• Relevant to the issue of food chains and the importance of keystone
species is a very short video called “How Wolves Change Rivers”:
http://www.youtube.com/watch?v=ysa5OBhXz-Q
• For more on bottled water, see the PowerPoint on my home page
(apparently, as of 2004, 26 billion water bottles were consumed
every year in the U.S.!).
• Does anyone have any stories relating to personal experiences with
water quality or quality. Matt mentioned needing to take bottled
water when out fishing. Anyone ever lived on an island with water
issues? Or gone overseas where there were water issues?
• For more on the role of plastic in relation to marine birds, see
http://www.youtube.com/watch?v=pUM58LIU2Lo.
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Upon successfully completing this chapter,
you will be able to
• Identify physical, geographical, chemical, and biological
aspects of the marine environment
• Describe major types of marine ecosystems
• Outline historic and current human uses of marine
resources
• Assess human impacts on marine environments
• Review the current state of ocean fisheries and reasons for
their decline
• Evaluate marine protected areas and reserves as innovative
solutions
• If you get a chance, watch “Blue Planet” on your own,
since we won’t have time to watch it in class.
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13-3
Central Case: Lesson learned: The Collapse
of the Cod Fisheries
• No fish has more impact on
human civilization than the
Atlantic cod
• Eastern Canadian and New
England fishermen have
fished for cod for generations
• Large ships and technology
have destroyed the cod
fishery
• Even protected stocks are not
recovering or recovering only
very slowly
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13-4
Cod are groundfish and inhabit the Grand
and Georges Bank
• Groundfish = fish that 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
• There are 24 stocks of cod
• Exclusive Economic Zone = legal
right to waters 200 nautical miles
from shore
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13-5
The Ocean
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13-6
Ocean cover most of Earth’s surface
• The oceans influence global climate, teem with
biodiversity, facilitate transportation and commerce,
and provide resources for us
• Oceans influence
the atmosphere,
lithosphere, and
biosphere
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13-7
The oceans contain more than water
• 96.5% water
• Ions of dissolved salts
• Nutrients
(e.g. nitrogen and
phosphorus)
• Dissolved gas
- Oxygen is added by
plants, bacteria, and
atmospheric
diffusion
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13-8
Ocean water is vertically structured
• Temperature declines with depth
• Heavier (colder saltier) water sinks
• 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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13-9
Ocean water is vertically structured (cont’d)
• Thermocline = below surface water, temperature
decreases rapidly with depth
• Halocline = salinity changes with increasing depth
• 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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13-10
Ocean water flows vertically and
horizontally, influencing climate
• Upwelling = the vertical flow of cold, deep water
towards the surface
- High primary productivity and lucrative fisheries
- Where winds blow away from, or parallel to,
coastlines
• Downwelling = oxygen-rich water sinks where surface
currents come together
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13-11
Upwelling
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13-12
The upper waters of the oceans flow
horizontally in currents (cont’d)
• Thermohaline circulation = global oceanic circulation
system of upwelling and downwelling currents
• Ocean water flows horizontally – wind systems and air
pressure
• Gyre = an oceanic current that flows in a circular motion
- Coriolis force = artifact of Earth’s rotation
• There is concern that climate change might disrupt both
the thermohaline circulation and gyres/ currents (such as
the Gulf Stream that keeps the UK temperate)
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13-13
The upper waters of the oceans flow horizontally in currents
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Great Pacific Garbage Continent
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La Niña and El Niño demonstrate the
atmosphere-ocean connection
• El Niño
- Equatorial winds weaken
- Warm water flows eastward and suppresses upwellings
- Alter weather worldwide
- Canada abnormally warm and dry
• La Niña
- Opposite to El Niño
- Weather: Canada abnormally cool and wet
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13-16
Seafloor topography can be rugged and
complex
• The seafloor consists of:
- Volcanoes
- Steep canyons
- Mountain range
- The planet’s longest
range is under water
- Mounds of debris
- Trenches
- Some flat areas
- And fault lines!
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13-17
Seafloor topography can be rugged and
complex (cont’d)
• 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
• Continental slope = connects the continental shelf to the
ocean floor
• Abyssal plain = flat bottom of the deep ocean
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13-18
A stylized bathymetric profile of the ocean
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13-19
Marine and Coastal Ecosystems
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13-20
Marine and coastal ecosystems
• Some zones support more life than others
• Photic zone = well-lit 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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13-21
Open-ocean systems vary in their biological
diversity
• Phytoplankton constitute
the base of the marine food
chain in the pelagic zone;
they are being affected by
increasing ocean acidity
• Zooplankton feed on them
• Fish, jellyfish, whales, feed
on zooplankton
• Predators at higher trophic
levels include larger fish,
sea turtles, sharks, and fisheating birds
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13-22
Open-ocean systems vary in their
biological diversity (cont’d)
• Animals adapt to extreme water
pressure and the absence of light
- Scavenge carcasses or organic
detritus
- Some are predators, others
have mutualistic relationships
with bacteria
- Some carry bacteria that
produce light chemically by
bioluminescence
• Hydrothermal vents support
chemosynthetic species
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13-23
Shallow-water systems are highly
productive
• Kelp = large, dense, brown algae growing from the floor
of continental shelves
• Dense strands provide shelter and food for organisms
• Underwater forests
• Absorbs wave energy and protects shorelines from
erosion
• Alginates serve as thickeners in cosmetics, paints, paper,
and soaps
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Shallow-water systems are highly productive
(cont’d)
• Coral reef = a mass of calcium carbonate
composed of the skeletons of corals
• Located in shallow subtropical and tropical
waters
- 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
- Are in real trouble because of climate change
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Shallow-water systems are highly productive
(cont’d)
• Corals = tiny colonial marine organisms
- Related to sea anemones and jellyfish
- Remain attached to rock or existing
reef
- Capture passing food with stinging
tentacles
- Derive nourishment from symbiotic
algae, zooxanthallae
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Shallow-water systems are highly productive
(cont’d)
• Coral bleaching = occurs when
zooxanthellae leave the coral
- Coral die, leaving white
patches
• Nutrient pollution causes algal
growth, which covers coral
• Divers damage reefs by using
cyanide to capture fish
• Acidification of oceans deprives
corals of carbonate ions
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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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Coastal ecosystems protect shorelines
• Salt marsh = occur along coasts at temperate
latitude (small vestiges remain in Victoria and
Esquimalt)
- 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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Coastal ecosystems protect shorelines
(cont’d)
• Mangroves = trees with
unique roots
- Curve up for oxygen
- Curve down for support
• Nurseries for commercial fish
and shellfish
• Nesting areas for birds
• Food, medicine, tools,
construction materials
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Coastal ecosystems protect shorelines
(cont’d)
• Mangroves are threatened:
- Threatened by development and 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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Freshwater meets saltwater in estuaries
• 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 – e.g. salmon
• Affected by development, pollution, habitat alteration,
and overfishing
• Anyone know what has compromised the health of the
Nanaimo Estuary?
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Human Use and Impact
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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 and minerals
• 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 energy and minerals (cont’d)
• 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 and
marine life
• 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 their 25th annual cleanup, Ocean Conservancy’s International
Coastal Cleanup, almost 500,000 volunteers from more than 100
nations, picked up 16 million kg of trash
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Marine pollution threatens resources and
marine life (cont’d)
• Plastic dumped into
the sea harms wildlife
- Mistake floating
plastic debris for
food
• Most plastic is nonbiodegradable
- Drifts for decades
• Marine debris affects
people
- Equipment damage
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See Chris Jordan’s trailer for his new film,
Midway, at http://www.midwayfilm.com/.
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Marine pollution threatens resources and
marine life (cont’d)
• Ocean acidification
- Decrease in acidity (pH) of ocean water
- Caused by uptake of atmospheric carbon
dioxide
- Corals and other marine organisms that
build their shells are at risk
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Oil pollution comes from many sources
• Major oils spills (i.e., the Exxon
Valdez, BP Deepwater Horizon)
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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Pollutants can contaminate seafood
• Mercury contamination
- From coal combustion and other sources
- Bioaccumulates and biomagnifies
- Dangerous to young children and pregnant or nursing
mothers
- Avoid eating fish and shellfish at high trophic levels
- Avoid seafood from areas where health advisories
have been issued
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Excess nutrients cause algal blooms
• Algal blooms = nutrients increase
populations of algae that produce
powerful toxins
• Red tide = blooms of algal species
that produce reddish pigments and
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 Ocean
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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
• 2006 study in Science:
- Predicted that populations of all ocean species
we fish for today will collapse by the year 2048
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We have long overfished
• 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
• People never imagined that groundfish could be
depleted
- New approaches or technologies increased
catch rates
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Fishing has become industrialized
• Driftnets for schools of herring,
sardines, mackerel, sharks
• Longline fishing for tuna and
swordfish
• Bottom-trawling for pelagic fish
and groundfish
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Some fishing practices kill nontarget
animals and damage ecosystems
• By-catch = the accidental capture of animals
• Driftnetting drowns dolphins, turtles, and seals
- 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
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Some fishing practices kill non-target
animals and damage ecosystems (cont’d)
• 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
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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
- Fishing in deeper water
- 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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Aquaculture has benefits and drawbacks
• Aquaculture = farm fisheries
- 30% of the world’s fish production
- Canada is fourth-largest producer of farmed salmon
in the world
- Freshwater fish and shellfish (clams, oysters,
mussels)
- Canada is now authorizing the production of GM
salmon
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Aquaculture has benefits and drawbacks
(cont’d)
• Benefits
- Improves food security
- Reduces pressure on wild stocks
- 10 to 1000 times more energy-efficient
• Drawbacks
- Increased disease causes antibiotic use
- High-density fishery causes more waste
- Can damage landscape
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Consumer choice can influence marine
harvest practices
• Buy eco-labeled seafood
- Dolphin-safe or, better yet, pole and line, tuna
• Use consumer guides
- SeaChoice or Seafood Watch seafood guides
- Some best choices: farmed catfish and caviar,
sardines, Canadian snow crab, Pacific halibut,
trap-caught shrimp
- Some to avoid: Atlantic cod and halibut, wild
caviar, imported King crab, shark, farmed shrimp
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weighing
the issues
Eating Seafood
After reading this chapter,
•Do you plan to alter your decisions about
eating seafood in any way? If so, how? If not,
why not?
•Do you think consumer buying choices can
exert an influence on fishing practices? On
mercury contamination in seafood?
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Marine biodiversity loss erodes ecosystem
services
• 2006 study in Science, showed effects of biodiversity loss
on ecosystem
- Less primary and secondary production
- Less able to withstand disturbance
- Reduced habitats for fish and shellfish
- Reduced filtering and detoxification
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Marine Conservation
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Fisheries management has been based on
maximum sustainable yield
• Maximum sustainable yield = Maximal harvest while
keeping fish available for the future
• Despite management, stocks have plummeted
• 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 can work for both fish and
fishers
• Found that reserves do work as win-win solutions
• In 2001 census by marine scientists stated, that in
addition to boosting fish biomass, total catch, and
record-sized fish, marine reserves:
- Within reserve boundaries
- Produce rapid and long-term abundance, diversity,
and productivity
- Decrease mortality and habitat destruction
- Lessen the likelihood of extirpation
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Reserves can work for both fish and
fishers (cont’d)
• Marine reserves:
- Outside reserve boundaries
- “Spillover effect” = protected species spread
outside reserve
- Larvae of protected species “seed the sea”
outside the reserve
- 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 contains diverse
topography and ecosystems
• We are learning about the oceans and coastal
environments, intensifying our use of their resources
and causing more severe impacts
• Setting aside protected areas of the ocean can serve to
maintain natural systems and enhance fisheries
• Look beyond simply making fisheries stable and
instead consider restoring 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) Corals reproduce
b) Fish move into coral reefs
c) Zooxanthellae leave the coral
d) 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?
FIGURE 12.20
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) Canada is not included in
this graph
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