Download Chapter 16 Notes - Lincoln High School

Lecture Outlines
Chapter 16
Marine and Coastal Systems
and Resources
Withgott/Laposata
Fifth Edition
© 2014 Pearson Education, Inc.
This lecture will help you understand:
§  The marine environment
§  Ocean-climate relationships
§  Marine ecosystems
§  Marine pollution
§  The state of ocean fisheries
§  Marine protected areas and reserves
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Central Case Study: Collapse of the Cod
Fisheries
§  No fish has had more impact on civilization than the
Atlantic cod
§  Cod have been fished for centuries
§  Cod are groundfish, fish that live or feed along the
bottom (also halibut, pollack, flounder)
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Central Case Study: Collapse of the Cod
Fisheries
§  Cod eat small fish and invertebrates
§  They inhabit cool waters on both sides of the Atlantic
§  Large ships and technology have overfished the cod
§  Cod populations shrank in the 1980s and crashed in
the early 1990s
§  Some stocks dropped to just 10% of their former
levels
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Central Case Study: Collapse of the Cod
Fisheries
§  Fishing for cod was temporarily banned in numerous
fisheries
§  Cod fishing was a major source of employment and
income for many areas along the Atlantic coast
§  Governments paid people for some of their lost wages
when fishing cod was banned
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Central Case Study: Collapse of the Cod
Fisheries
§  Even with the fishing ban, stocks of cod were not
recovering
§  Fish that had been cod prey were eating young cod
§  Bans were extended
§  A 2011 study showed that cod stocks were finally
beginning to recover
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
The Oceans
§  Oceans are an important part of the Earth’s
interconnected aquatic systems
§  Receive most inputs of water sediments, pollution
§  Oceans influence climate, teem with biodiversity,
provide resources, and help transportation and
commerce
§  Oceans cover 71% of Earth’s surface and contain
97.5% of its water
§  They are a single vast body of water
§  Oceans influence the atmosphere, lithosphere, and
biosphere
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Seafloor topography can be rugged
§  The seafloor consists of underwater volcanoes, steep
canyons, mountain ranges, vast trenches, mounds of debris,
and some flat areas
§  We can look at the ocean’s bathymetry (depths) and
topography (landforms)
§  Continental shelves = areas of shallow, gently sloping
sea floor next to the continents
§  Sea floor angles down from there at the self-slope break
§  The continental slope then drops to the deep ocean
basin below
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Seafloor topography can be rugged
§  Some island chains are formed by reefs on the
continental shelf (e.g., Florida Keys)
§  Others are volcanic in origin (e.g., Aleutian Islands)
§  Where underwater structures exist, life thrives
§  Topographically complex areas serve as habitat and
make for productive fishing grounds
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Ocean water contains high concentrations of
dissolved salt
§  Ocean water is 96.5% water by mass
§  Remainder is mostly ions of dissolved salts
§  Ocean water is over 33,000 parts per million salts,
fresh water is 500 ppm
§  Salts enter oceans in runoff from the land
§  Evaporation removes pure water, leaving salt behind
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Ocean water contains high concentrations of
dissolved salt
§  Oceans contain low levels of nutrients (nitrogen and
phosphorus)
§  Oxygen is added by plants, bacteria, and
atmospheric diffusion
§  Carbon dioxide enters the oceans from the
atmosphere
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Solar energy structures ocean water from
surface to bottom
§  Water temperature declines with depth
§  Heavier (colder, saltier) water sinks; light (warmer,
less salty) water stays near the surface
§  Surface zone
§  Warmed by sunlight and stirred by wind
§  Consistent water density down to about 150m
§  Contains about 2% of the oceans water
§  Pycnocline = zone below the surface
§  Density increases rapidly with depth
§  Contains about 18% of ocean water
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Solar energy structures ocean water from
surface to bottom
§  Deep zone = zone below the pycnocline; remaining 80%
§  Dense, sluggish water
§  Unaffected by winds, storms, sunlight, temperature
§  Temperatures are more stable than land temperatures
§  Water has high heat capacity = heat required to increase
temperature by a given amount
§  It takes more energy to warm water than air
§  Oceans regulate Earth’s climate
§  They absorb and release heat
§  The ocean’s surface circulation moves heat around
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Surface water flows horizontally in currents
§  Currents = vast riverlike flows in the oceans
§  Move horizontally in the upper 400 m of water
§  Driven by density differences, heating and cooling,
gravity, and wind
§  Some currents such as the Gulf Stream are rapid
and powerful
§  The warm water moderates Europe’s climate
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Surface water flows horizontally in currents
§  Currents have helped carry people across the globe
§  Also transport heat, nutrients, pollution, and the larvae
of many marine species
§  Pacific Ocean currents transported debris from the
tsunami in Japan to the western U.S. coast
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Vertical movement of water affects marine
ecosystems
§  Upwelling = the upward flow of cold, deep water
toward the surface
§  Water is rich in nutrients
§  Sites of high primary productivity and lucrative
fisheries
§  Also occurs where strong winds blow away from, or
parallel to, coastlines
§  Downwelling = process in which oxygen-rich water
sinks where surface currents come together
§  “Buries” CO2 in the deep waters
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Ocean currents affect Earth’s climate
§  Horizontal and vertical movement of oceans affects
global and regional climates
§  Thermohaline circulation = a worldwide current system
§  Warmer, fresher water moves along the surface
§  Cooler, saltier, denser water moves deep beneath the
surface
§  North Atlantic Deep Water (NADW) = one part of the
thermohaline conveyor belt
§  Water in the Gulf Stream flows to Europe
§  Released heat keeps Europe warmer than it would be
§  Sinking cooler water creates a region of downwelling
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Ocean currents affect Earth’s climate
§  Interrupting the thermohaline circulation of the
NADW could trigger rapid climate change
§  Melting ice from Greenland will run into the North
Atlantic, making surface waters less salty, less dense
§  Could stop NADW formation and shut down the
northward flow of warm water
§  Europe would rapidly cool
§  This circulation is already slowing
§  But Greenland may not have enough runoff to stop it
© 2014 Pearson Education, Inc.
Ocean currents affect Earth’s climate
§  El Niño–Southern Oscillation (ENSO) = a
systematic shift in atmospheric pressure, sea
surface temperature, and ocean circulation in the
tropical Pacific Ocean
§  Normal winds blow east to west, from high to low
pressure
§  This forms a large convective loop in the atmosphere
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Ocean currents affect Earth’s climate
§  Winds push water west, causing it to “pile up”
§  Nutrient-rich, cold water along Peru and Ecuador rises
from the deep
§  Decreased pressure in the eastern Pacific triggers
El Niño
§  Warm water flows eastward, suppressing upwellings
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Ocean currents affect Earth’s climate
§  Coastal industries (e.g., Peru’s anchovy fisheries) are
devastated (no upwelling means low productivity)
§  Worldwide, fishermen lost $8 billion in 1982–1983
§  Global weather patterns change
§  Rainstorms, floods, drought, fires
§  La Niña = the opposite of El Niño
§  Cold waters rise to the surface and extend westward
§  ENSO cycles are periodic but irregular (every 2–8 years)
§  Globally warming sea and air may be increasing the
strength and frequency of these cycles
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Climate change is altering ocean chemistry
§  Global climate change will affect ocean chemistry and
biology
§  Burning fossil fuels and removing vegetation increase
CO2, which warms the planet
§  Oceans absorb carbon dioxide (CO2) from the air
§  But oceans may not be able to absorb much more CO2
§  Increased CO2 in the ocean makes it more acidic
§  Ocean acidification makes chemicals less available for
sea creatures (e.g., corals) to form shells
§  Fewer coral reefs means decreased biodiversity and
ecosystem services
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Marine and Coastal Ecosystems
§  Regions of ocean water differ greatly
§  Some zones support more life than others
§  Photic zone = well-lighted top layer
§  Absorbs 80% of solar energy
§  Supports high primary productivity
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Marine and Coastal Ecosystems
§  Pelagic = habitats and ecosystems between the
ocean’s surface and floor
§  Benthic = habitats and ecosystems on the ocean
floor
§  Most ecosystems are powered by solar energy
§  But even the darkest depths host life
§  Marine systems are interconnected with freshwater
ones
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Intertidal zones undergo constant change
§  Intertidal (littoral) ecosystems = 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
§  High and low tides occur roughly 6 hours apart
§  Intertidal organisms spend part of their time
submerged in water and part of their time exposed to
sun and wind
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Intertidal zones undergo constant change
§  Intertidal zones are a tough place to live, but they
have amazing 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
§  Environmental variation creates horizontal bands of
habitat
§  Sandy intertidal zones have slightly less biodiversity
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Salt marshes line temperate shorelines
§  Salt marshes = occur along coasts at temperate latitudes
§  Tides wash over gently sloping sandy, silty substrates
§  Rising and falling tides flow into and out of channels
called tidal creeks and overflow onto marsh flats
§  Salt marshes have very high primary productivity
§  Thick with salt-tolerant grasses, sedges, shrubs
§  Critical habitat for birds, commercial fish, and shellfish
§  They filter pollution
§  They stabilize shorelines against storm surges
§  Many have been lost because people want to live or do
business along coasts
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Mangrove forests line coasts in the tropics and
subtropics
§  In tropical and subtropical latitudes mangrove forests
replace salt marshes along sandy coasts
§  Mangroves = salt-tolerant trees that can live in
changing water levels
§  Their unique roots curve up for oxygen and down for
support
§  Provide nesting areas for birds, nurseries for fish
and shellfish, food, medicine, tools, and construction
materials
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Mangrove forests line coasts in the tropics and
subtropics
§  Half the world’s mangrove forests are gone
§  Developed for residential, commercial, and
recreational uses
§  Removed for shrimp farming
§  Once destroyed, coastal areas no longer:
§  Slow runoff
§  Filter pollutants
§  Retain soil
§  Protect communities against storm surges
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Fresh meets salt water in estuaries
§  Estuaries = water bodies where rivers flow into the
ocean, mixing fresh and salt water
§  They are biologically productive
§  Have fluctuations in salinity
§  Critical habitat for shorebirds and shellfish
§  Transitional zone for fish that spawn in streams and
mature in salt water
§  They have been affected by development, pollution,
habitat alteration, and overfishing
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Kelp forests harbor many organisms
§  Kelp = large, dense, brown algae growing from the
floor of continental shelves
§  Can reach 60 m (200 ft) long and grow 45 cm (18 in)
per day
§  Dense strands form kelp forests along temperate
coasts
§  They provide shelter and food for organisms
§  They absorb wave energy and protect shorelines from
erosion
§  People use kelp in food, cosmetics, paints, paper,
soap, etc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Coral reefs are treasure troves of biodiversity
§  Coral reef = a mass of calcium carbonate composed
of the skeletons of tiny marine animals (corals)
§  May be an extension of a shoreline
§  Or exist along a barrier island, parallel to the shore
§  Or as an atoll (a ring around a submerged island)
§  Corals are tiny colonial invertebrate animals related
to sea anemones and jellyfish
§  Attach to a rock or reef and capture passing food with
stinging tentacles
§  Get nourishment from symbiotic algae (zooxanthallae)
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Coral reefs are treasure troves of biodiversity
§  Reefs consist of millions of densely packed animals
§  Colors come from zooxanthellae
§  Reefs are located in shallow subtropical and tropical
waters
§  Protect shorelines by absorbing waves
§  Reefs provide complex physical structure
§  High primary productivity
§  Innumerable invertebrates and fish species find food
and shelter in reef nooks and crannies
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Coral reefs are treasure troves of biodiversity
§  Coral bleaching occurs when zooxanthellae leave
the coral or die
§  Corals lose their color and die, leaving white patches
§  Results from climate change, pollution, or unknown
natural causes
§  Nutrient pollution causes algal growth, which
smothers coral
§  Divers damage reefs by using cyanide to capture
fish
§  Acidification of oceans deprives corals of carbonate
ions for their structural parts
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© 2014 Pearson Education, Inc.
Coral reefs are treasure troves of biodiversity
§  A few coral species thrive in waters outside the
tropics
§  On the ocean floor at depths of 200–500 meters
(650–1650 ft)
§  Occur in cold-water areas off the coasts of Spain, the
British Isles, and elsewhere
§  Little is known about these reefs
§  Already, many have been badly damaged by trawling
§  Some reefs are now being protected
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Open-ocean ecosystems vary in their
biodiversity
§  Microscopic phytoplankton are the base of the
marine food chain
§  Productivity is concentrated in areas of nutrient-rich
upwelling
§  Algae, protists, cyanobacteria feed zooplankton,
which then feed fish, jellyfish, whales, etc.
§  Predators at higher trophic levels
§  Larger fish, sea turtles, sharks, and fish-eating birds
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Open-ocean ecosystems vary in their
biodiversity
§  Animals of the deep ocean have adapted to extreme
water pressure and the dark
§  Some scavenge carcasses or organic detritus
§  Others are predators
§  Others have mutualistic relationships with bacteria
§  Hydrothermal vents support tubeworms, shrimp, and
chemosynthetic bacterial species
§  Derive energy from chemicals in the heated water
rather than photosynthesis
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Marine Pollution
§  People use oceans as a sink for waste and pollutants
§  Even into the mid-20th century, coastal U.S. cities
dumped trash and untreated sewage along their shores
§  Non-point-source pollution comes from all over
§  Oil, plastic, chemicals, excess nutrients
§  Also sewage and trash from cruise ships and abandoned
fishing gear
§  Over 25 years, Ocean Conservancy volunteers picked
up 65 million kg (144 million lb) of waste from the world’s
beaches
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Plastic debris endangers marine life
§  Plastic items dumped into the sea harm or kill wildlife
§  Organisms can become entangled in debris and
drown
§  May die from material eaten that they cannot expel
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Plastic debris endangers marine life
§  Areas where circulating currents converge called
gyres bring and trap plastic trash
§  The North Pacific Gyre contains the Great Pacific
Garbage Patch = an area larger than Texas where
floating plastic bits outnumber organisms by a 6 to 1
margin
§  Plastic is designed not to break down so may drift for
decades
§  Breaks into tiny pieces over time
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Plastic debris endangers marine life
§  Trillions of tiny plastic pellets float in the oceans
§  Some of the pellets sink, accumulating on the ocean floor
where they do not degrade
§  Organisms mistake the floating plastic for food
§  The average fish in the great Pacific Garbage Patch had
over two pieces of plastic in its digestive tract
§  Over 40% of Albatross chick premature deaths have been
attributed to pieces of plastic in their food
§  Over 260 species are affected by marine plastic debris
§  Leads to an estimated 100,000 marine mammal and 1
million seabird deaths each year
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Plastic debris endangers marine life
§  Ingested plastics can also have toxic effects
§  Plastics themselves contain harmful substances such as
bisphenol A and pthalates
§  May concentrate persistent organic pollutants
§  Floating debris can transport organisms great distances
§  Some of these become invasive species
§  Plastics are not easily removed, so prevention is key
§  The 2006 Marine Debris Research, Prevention, and
Reduction Act aids these efforts
§  Plastic pollution costs Asia over $1 billion in its fisheries
and tourism industries
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Oil pollution comes from spills of all sizes
§  About 30% of oil and 50% of natural gas come from
seafloor deposits
§  North Sea, Gulf of Mexico
§  Drilling in other places is banned
§  Spills could harm valuable fisheries
§  The Deepwater Horizon exploded off Louisiana’s
coast
in April 2010
§  Spilled 1800 gallons/min for 3 months
§  Hit coasts of four states
§  Even ocean floor species miles away were affected
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Oil pollution comes from spills of all sizes
§  Major spills make headlines
§  Foul beaches, coat and kill animals, devastate
fisheries
§  Countless non-point sources produce most oil
pollution
§  Half of all oil comes from natural oil seeps
§  Also small boat leaks, runoff from land
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Oil pollution comes from spills of all sizes
§  Stricter regulations for oil tankers have been enacted
by many governments
§  The U.S. Oil Pollution Act (1990) created a $1 billion
prevention and cleanup fund
§  Requires that all ships have double hulls by 2015
§  Spills from tankers have decreased over the last 30
years
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Toxic pollutants can contaminate seafood
§  Toxic pollutants can make food unsafe to eat
§  Mercury contamination from coal combustion and other
sources bioaccumulates and biomagnifies
§  Dangerous to children and pregnant or nursing women
§  Highest mercury levels will be in fish at the top of the
food chain
§  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
§  Nutrient runoff can allow explosive growth of marine
algae populations
§  Harmful algal blooms = blooms where nutrients
increase algae that produce powerful toxins
§  Dinoflagellate algae toxins attack the nervous system
§  Red tide = algae that produce red pigments that
discolor water
§  Cause illness and death among wildlife and humans
§  Economic loss to fishing industries and beach tourism
§  Reduce nutrient runoff
§  Do not eat affected organisms
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© 2014 Pearson Education, Inc.
Emptying the Oceans
§  Overharvesting is the worst marine problem
§  We are putting unprecedented pressure on marine
resources
§  Half the world’s marine fish populations are fully
exploited and can’t be fished more intensively
§  28% of fish population are overexploited and heading
to extinction
§  Total fisheries catch leveled off after 1988 despite
increased fishing effort
§  The maximum wild fisheries potential has been
reached
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Emptying the Oceans
§  If current trends continue, it is predicted that populations
of all ocean species we fish for today will collapse by
2048
§  If fisheries collapse as predicted, we will lose their
ecosystem services
§  Productivity will decline, and they will become more
sensitive to disturbance
§  Filtering of water will decline, causing more harmful algal
blooms and beach closures
§  Aquaculture is relieving some of the pressure on wild
stocks, but it has its own set of environmental problems
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We have long overfished
§  People began depleting sea life centuries ago
§  Species have been hunted to extinction: Caribbean
monk seal, Steller’s sea cow, Atlantic gray whale
§  Decreased sea turtle populations cause overgrowth of
sea grass and can cause sea grass wasting disease
§  Overharvesting nearly exterminated many whale species
§  People never thought groundfish could be depleted
§  Local populations dwindled as far back as the 19th century
§  New approaches or technologies were needed to increase
catch rates
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Fishing has industrialized
§  Factory fishing = huge vessels use powerful
technologies to capture fish in huge volumes
§  Driftnets = transparent nylon mesh nets that drift
with the current
§  Used for herring, sardines, mackerel, sharks, shrimp
§  Longline fishing = extremely long (up to 80 km or
50 mi) lines with several thousand baited hooks
§  Used for tuna and swordfish
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Fishing has industrialized
§  Trawling = using cone shaped nets with weights at
the bottom and floats at the top to catch pellagic fish
§  Bottom trawling = using weighted nets that drag
across the seafloor to catch groundfish or scallops
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© 2014 Pearson Education, Inc.
Fishing practices kill nontarget animals and
damage ecosystems
§  Bycatch = the accidental capture of animals
§  A 2011 report found that 17% of all commercially
harvested fish were captured unintentionally
§  Driftnetting drowns dolphins, turtles, and seals
§  Fish die on deck
§  Banned in international waters
§  But is still used in national waters
§  Longline fishing kills turtles, sharks, and over
300,000 seabirds/year
§  Methods (e.g., flags) are being developed to limit
bycatch
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Fishing practices kill nontarget animals and
damage ecosystems
§  Dolphins are trapped in nets used to catch tuna
§  Hundreds of thousands of dolphins were killed
§  The 1972 Marine Mammal Protection Act forced fleets to
try to free dolphins
§  Bycatch dropped dramatically
§  Other nations fished for tuna, and bycatch increased
§  The U.S. government required that nations exporting
tuna to the United States minimize dolphin bycatch
§  “Dolphin-safe” tuna uses methods to avoid bycatch
§  Other species (sharks) are still being caught
§  Dolphin populations have not yet recovered
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© 2014 Pearson Education, Inc.
Fishing practices kill nontarget animals and
damage ecosystems
§  Bottom trawling causes bycatch and harms entire
ecosystems
§  Heavy nets crush organisms and damage sea bottoms
§  Especially destructive to complex areas (e.g., reefs)
§  It equals clear-cutting and strip mining
§  The average spot of the sea floor in the Georges Bank
has been trawled three times, destroying young cod as
bycatch
§  Bycatch of cod while fishing for other species in the
Grand Banks nearly doubled from 2006 to 2009
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© 2014 Pearson Education, Inc.
Modern fishing fleets deplete marine life rapidly
§  Grand Banks cod have been fished for centuries
§  Catches more than doubled with industrial trawlers
§  Record-high catches lasted only 10 years
§  Georges Bank cod fishery also collapsed
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Modern fishing fleets deplete marine life rapidly
§  Worldwide, industrialized fishing is depleting marine
populations with astonishing speed
§  90% of large-bodied fish and sharks are eliminated
within 10 years after fishing begins
§  Populations stabilize at 10% of their former levels
§  Communities were very different before modern
fishing
§  Removing animals at higher trophic levels allows prey
to proliferate and change communities
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© 2014 Pearson Education, Inc.
Several factors mask declines
§  Industrialized fishing has depleted stocks
§  But global catch has remained stable for the past 20 years
§  How can stability mask population declines?
§  Fishing fleets travel farther to reach less-fished areas
§  Fleets fish in deeper waters (now at 250 m)
§  Fleets spend more time fishing and set more nets
§  Improved technologies: faster ships, sonar mapping,
satellite navigation, thermal sensing, aerial spotting
§  Fleets expend more effort to catch the same number of
fish
§  At some point, there will not be enough fish left
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We are “fishing down the food chain”
§  Figures on total global catch do not tell the whole story
§  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 more
abundant species
§  Shift from large, desirable species to smaller, less
desirable ones
§  This entails catching species at lower trophic levels
§  “Image makeovers” renamed formerly undesirable fish
§  “Orange roughy” was once called “slimehead”
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Marine biodiversity loss erodes ecosystem
services
§  Factors that deplete biodiversity threaten ecosystem
services we get from the oceans
§  Systems with reduced species or genetic diversity
show less primary and secondary production
§  They are less able to withstand disturbance
§  Biodiversity loss reduces habitat for nurseries for fish
and shellfish
§  Less diversity leads to reduced filtering and
detoxification, resulting in algal blooms, dead zones,
fish kills, beach closures
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Fisheries management has been based on
maximum sustainable yield
§  Maximizes harvest while maintaining fish for the future
§  Managers may limit the harvest or restrict gear used
§  Despite management, stocks have plummeted
§  Requires accurate measurement of fish numbers
§  Overestimates have resulted in overharvesting
§  Ecosystem-based management shifts away from
species and toward the larger ecosystem
§  Considers the impacts of fishing on habitat quality, species
interactions, and long-term effects
§  Sets aside areas of oceans free from human interference
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We can protect areas in the ocean
§  Marine protected areas (MPAs) = most are along
the coastlines of developed countries
§  They 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 and recreational fishers and
businesses do not support reserves
§  To be successful, establishment needs to be sensitive
to concerns of local residents
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Reserves can work for both fish and fishers
§  A 2001 review showed that after just one to two
years of establishment, marine reserves:
§  Increased densities of organisms by 91%
§  Increased biomass by 192%
§  Increased organism size by 31%
§  Increased species diversity by 23%
§  Benefits inside reserve boundaries include:
§  Rapid and long-term increases in abundance,
diversity, and productivity of marine organisms
§  Decreased mortality and habitat destruction
§  Decreased likelihood of extirpation of species
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Reserves can work for both fish and fishers
§  Areas outside reserves also benefit
§  A “spillover effect” occurs 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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Reserves can work for both fish and fishers
§  Local residents who were opposed changed to
supporting reserves once they saw their benefits
§  Once commercial trawling was stopped on Georges
Bank:
§  Populations of organisms began to recover
§  Fishing in adjacent waters increased
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How should reserves be designed?
§  Reserves should be able to
§  Protect ecosystems
§  Sustain fisheries
§  Include people
§  Most studies suggest that 20–50% of the ocean
should be protected in no-take reserves
§  How large should the reserves be?
§  How many should we have?
§  Where should they be located?
§  Involving fishers is crucial in coming up with answers
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Conclusion
§  Oceans cover most of our planet and contain diverse
topography and ecosystems
§  As we learn about oceans and coastal
environments, we are intensifying our use of their
resources and causing severe impacts
§  We need to address acidification, loss of coral reefs,
pollution, and fisheries depletion
§  Setting aside protected areas can maintain and
restore natural systems and enhance fisheries
§  Consumer choices can help us move toward
sustainable fishing
© 2014 Pearson Education, Inc.
QUESTION: Review
A “downwelling” is
a)  the vertical flow of cold, deep water toward the
surface.
b)  the vertical flow of warm, deep water toward the
surface.
c)  when oxygen-rich water sinks.
d)  when oxygen-poor water sinks.
© 2014 Pearson Education, Inc.
QUESTION: Review
The area of an ocean that contains habitats on the
ocean floor is called the _______ zone.
a)  littoral
b)  photic
c)  pelagic
d)  benthic
© 2014 Pearson Education, Inc.
QUESTION: Review
An area that occurs along coasts at temperate
latitudes is called a(n)
a)  estuary.
b)  mangrove swamp.
c)  salt marsh.
d)  coral reef.
© 2014 Pearson Education, Inc.
QUESTION: Review
_____ is defined as “a mass of calcium carbonate
composed of the skeletons of tiny animals.”
a)  A coral reef
b)  Red tide
c)  Bottomfish
d)  Kelp
© 2014 Pearson Education, Inc.
QUESTION: Review
Which statement about coral bleaching is correct?
a)  Corals reproduce most efficiently in colder waters.
b)  Fish move into coral reefs and kill them.
c)  Zooxanthellae leave the coral due to climate change
or pollution.
d)  Coral reefs expand their range after they have been
bleached.
© 2014 Pearson Education, Inc.
QUESTION: Review
Which of the following does NOT mask the decline of
fisheries?
a)  Fishing fleets travel longer distances to reach lessfished areas.
b)  Fishing fleets spend more time fishing.
c)  Fishing fleets use sophisticated methods of fishing.
d)  Fleets fish in shallower waters nearer coasts.
© 2014 Pearson Education, Inc.
QUESTION: Review
Marine reserves have all the following benefits
EXCEPT
a)  fishing increases in areas surrounding the reserve.
b)  the size of fish decreases.
c)  larvae can “seed” areas outside the reserve.
d)  decreased mortality and habitat destruction occur.
© 2014 Pearson Education, Inc.
QUESTION: Viewpoints
What would you think about letting another country fish
10 miles off the U.S. coast?
a)  That’s fine, as long as the fleet paid the United
States.
b)  Let them fish, but make them follow the same rules
as U.S. fishermen.
c)  Let only U.S. fishermen fish in these waters.
d)  Prevent most fishing; we need to protect the last fish
stocks.
© 2014 Pearson Education, Inc.
QUESTION: Interpreting Graphs and Data
What does this graph show about the future of global
fisheries catch?
a)  World fish catch has plummeted.
b)  It is unlikely that world fish catch will increase.
c)  The world will decrease its fishing pressure.
d)  The United States is not included in this graph.
© 2014 Pearson Education, Inc.
QUESTION: Interpreting Graphs and Data
Which conclusion can you draw from this graph about
commercial catches of Atlantic cod?
a)  Intensified fishing
increased and the
fishery crashed.
b)  It is easier to find
fish today.
c)  There is little correlation
between fishing and
fish stocks.
d)  Moratoria will bring the
stocks back.
© 2014 Pearson Education, Inc.