Ch. 16 Notes APES

1

This chapter will help you understand:

• The marine environment

• Ocean-climate relationships

• Marine ecosystems

• Marine pollution

• The state of ocean fisheries

• Marine protected areas and reserves

Cod are groundfish

• Fish that live or feed along the bottom

- Halibut, pollack, flounder

• Cod eat small fish and invertebrates

• They inhabit cool waters on both sides of

the Atlantic

• The 24 _______________ (populations) of cod

crashed

- Overfishing and destroyed habitat

• The U.S. and Canada have paid billions to

retrain fishermen who lost their jobs.

Oceans cover most of the Earth’s surface

• Oceans influence climate, team with biodiversity, provide resources, and help transportation and

commerce

• Oceans cover _____% of Earth’s surface and contain __________% of its water

• Oceans influence the atmosphere, lithosphere, and biosphere

Seafloor topography can be rugged

• The seafloor consists of:

- Underwater volcanoes

- Steep canyons

- Mountain ranges

- Mounds of debris

- Trenches

- Some flat areas

• Some island chains are formed by reefs or

volcanoes

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- Topographically complex areas serve as habitat and productive fishing grounds

A stylized bathymetric profile of the ocean

• A stylized map reflects the ocean’s bathymetry (depths) and topography (landforms)

Ocean water contains salt

• Ocean water is __________% water

- Plus, ions of dissolved salts

• Evaporation removes pure water

- Leaving salt behind

• Low levels of nutrients (nitrogen and

phosphorus)

• Oxygen is added by plants, bacteria,

and atmospheric diffusion

Ocean water is vertically structured

• Temperature ___________________________

with depth

• Heavier (colder, saltier) water sinks

- Light (warmer, less salty) water

stays near the surface

• Temperatures are more stable than

land temperatures

- Water has high _____________

_____________________ (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

The ocean has several layers

• _____________________________ zone

- Warmed by sunlight and stirred by wind

- Consistent water density

• _____________________________ = below the surface

zone

- Density increases with depth

• ___________________ zone = below the pycnocline

- Dense, sluggish water

- Unaffected by winds, storms, sunlight, or

temperature

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3

Ocean water flows horizontally in currents

• _________________________ = vast riverlike flows in the oceans

- Driven by density differences, heating and cooling, gravity, and wind

- Influence global climate and El Niño and La Niña

- Transport heat, nutrients, pollution, the larvae of many marine species, and people

• Some currents such as the Gulf Stream are rapid and powerful

- The warm water moderates __________________________’s climate

Currents form patterns across the globe

Vertical movement affects ecosystems

• ______________________________ = the upward flow of cold, deep water toward 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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4

Currents affect climate

• Horizontal and vertical movement of oceans affects global and regional climates

• _______________________________ circulation = a worldwide current system

- Warmer, fresher water moves along the surface

- Cooler, saltier, denser water moves 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 that it would be

- Sinking cooler water creates a region of downwelling

The North Atlantic Deep Water

• Interrupting the thermohaline circulation could trigger rapid climate change

- Melting ice from Greenland will run into the North Atlantic

- Making surface waters even less dense

- Stopping NADW formation and shutting 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

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

• Winds push water west, causing it to “pile up”

- Nutrient-rich, cold water along Peru and Ecuador rises from the deep

• _________________________ pressure in the eastern Pacific triggers El Niño

- Warm water flows eastward, suppressing upwellings

Effects of El Niño and La Niña

• Coastal industries (e.g., Peru’s anchovy fisheries) are devastated

- Worldwide, fishermen lost $8 billion in 1982–1983

• Global weather patterns change

- Rainstorms, floods, drought, fires

• ___________________________ = 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

ENSO, El Niño, and La Niña

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Climate change is altering the oceans

• 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 ____________________

- Ocean acidification makes chemicals less available for sea creatures (e.g., corals) to form shells

- Fewer coral reefs decrease biodiversity and ecosystem services

Marine and coastal ecosystems

• Regions of ocean water differ greatly

- Some zones support more life than others

• ____________________ zone = well-lighted top layer

- Absorbs 80% of solar energy

- Supports high primary productivity

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• _______________________________ = habitats and ecosystems between the ocean’s surface and floor

• _______________________________ = habitats and ecosystems on the ocean floor

• Most ecosystems are powered by solar energy

- But even the darkest depths host life

Open ocean systems vary in biodiversity

• Microscopic phytoplankton are the base of the marine food chain

- Algae, protists, cyanobacteria

- They feed zooplankton

- Which then feed fish, jellyfish, whales, etc.

• Predators at higher trophic levels

- Larger fish, sea turtles, sharks, and fish-eating birds

Animals of the deep ocean

• Animals adapt to extreme water pressure and the dark

- Scavenge carcasses or organic detritus

- Predators

- Others have mutualistic relationships with bacteria

- Some carry bacteria that produce light chemically by bioluminescence

• Hydrothermal vents support tubeworms, shrimp, and other chemosynthetic species

Kelp forests harbor many organisms

• _______________ = large, dense, brown algae growing from the floor of continental shelves

• 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 it in food, cosmetics, paints, paper, soap, etc.

Coral reefs are treasure troves of biodiversity

• _______________ ________________ = a mass of calcium carbonate composed of the skeletons of tiny marine

animals (corals)

- They 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 = tiny colonial invertebrate animals

- Related to sea anemones and jellyfish

- Attach to a rock or reef and capture passing food with stinging tentacles

- Get food from symbiotic algae (zooxanthallae)

Most corals are colonial

• Reefs consist of millions of densely packed animals

• Reefs are located in shallow subtropical and tropical waters

- 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 or die

- Corals lose their color and die, leaving white patches

- From climate change, pollution, or unknown natural causes

• _____________________ 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

Deepwater coral reefs exist

• They thrive in waters outside the tropics

- On ocean floor at depths of 200–500 m (650–1,650 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

Intertidal zones undergo constant change

• _______________________________ (littoral) ecosystems = where the ocean meets the land

- Between the uppermost reach of the high tide and the lowest limit of the low tide

• _______________ = 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

A typical intertidal zone

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

Ch. 16 Notes APES

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• Temperature, salinity, and moisture change dramatically from high to low tide

• Sandy intertidal zones have slightly less biodiversity

Salt marshes line temperate shorelines

• _______________ ________________ = occur along coasts at temperate latitudes

- Tides wash over gently sloping sandy, silty substrates

• Tidal creeks = channels that rising and falling tides flow into and out of

• Salt marshes have very high primary productivity

- Critical habitat for birds, commercial fish, and shellfish

- They filter pollution

- They stabilize shorelines against storm surges

People change and destroy salt marshes

• People want to live or do business along coasts

- We lose key ecosystem services

- Flooding (e.g., from Hurricane Katrina) worsens

Mangrove forests line coasts

• In tropical and subtropical latitudes

- They replace salt marshes along sandy coasts

• _________________________ = salt-tolerant trees

- Their unique roots curve up for oxygen and down for support

• Nesting areas for birds

• Nurseries for fish and shellfish

• Mangroves provide food, medicine, tools, and construction materials.

Mangrove forests have been destroyed

• Half the world’s mangrove forests are gone

- Developed for residential, commercial, and recreational uses

- Shrimp farming

• Once destroyed, coastal areas no longer:

- Slow runoff

- Filter pollutants

- Retain soil

- Protect communities against storm surges

Fresh and salt water meet in 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

Ch. 16 Notes APES

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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

• Nonpoint source pollution comes from all over

- Oil, plastic, chemicals, excess nutrients

• In 2008, 391,000 Ocean Conservancy volunteers from 104 nations picked up 3.1 million kg (6.8 million lb)

of trash from 27,000 km (17,000 miles) of shoreline.

Nets and plastic debris endanger life

• Plastic items dumped into the sea harm or kill wildlife

- Wildlife mistake it for food

- 98% of dead northern fulmars had plastic in their stomachs

• Plastic is nonbiodegradable

- Drifts for decades

- Breaks into tiny pieces

• Trillions of tiny plastic pellets float in the oceans and are eaten.

Plastic trash is accumulating in the oceans

• Circulating currents bring and trap plastic trash to areas

- The northern Pacific Gyre stretches from California to Hawaii to Japan

- This “Great Pacific Garbage Patch” is the size of Texas and has 3.3 plastic bits/m2

• The 2006 Marine Debris Research, Prevention, and Reduction Act is not enough

• We must reduce, reuse, and recycle more plastic

- Participate in efforts such as the International Coastal Cleanup

Oil pollution comes from spills of all sizes

• 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

- Spilling 140 gallons/min

- Hitting coasts of four states

Oil spills have severe consequences

• Major spills make headlines

- Foul beaches

- Coat and kill animals

- Devastate fisheries

• Countless non-point sources produce most oil pollution

- Small boat leaks, runoff

Ch. 16 Notes APES

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Oil spills have decreased

• Due to emphasis on spill prevention and

response

- Stricter regulations are resisted by

the oil industry

• The U.S. Oil Pollution Act (1990)

- Created a $1 billion prevention and

cleanup fund

- Requires that all ships have double

hulls by 2015

• Recently, oil spills have decreased.

Toxic pollutants contaminate seafood

• Toxic pollutants can make food unsafe

to eat

• _____________________ contamination from

coal combustion and other sources

bioaccumulates and biomagnifies

- Dangerous to children and pregnant

or nursing women

• 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

Excess nutrients cause algal blooms

• Harmful algal blooms = nutrients increase algae that produce powerful toxins

• __________ __________ = algae that produce red pigments that discolor water

- Illness and death to wildlife and humans

- Economic loss to fishing industries and beach tourism

• Reduce runoff

• Do not eat affected organisms

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

Ch. 16 Notes APES

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The global fisheries catch has increased

• It is predicted that populations of all ocean species we

fish for today will collapse by 2048 .

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

• Overharvesting Chesapeake Bay oyster beds led to its

collapse, eutrophication, and hypoxia

• 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

- New approaches or technologies increased catch

rates

Fishing has industrialized

• ___________________________ fishing = huge vessels use

powerful technologies to capture fish in huge volumes

- Even processing and freezing their catches at sea

• Driftnets for schools of herring, sardines, mackerel,

sharks, shrimp

• Longline fishing for tuna and swordfish

• Trawling for pelagic fish and groundfish

Fishing practices kill nontarget animals

• _____________________ = the accidental capture of animals

• Drift netting drowns dolphins, turtles, and seals

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- Fish die on deck

- Banned in international waters

- But it 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

Dolphins and tuna

• Dolphins are trapped in purse seine 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 U.S. minimize dolphin bycatch

- Dolphin-safe tuna uses methods to avoid bycatch

Dolphin deaths have declined, but …

• Other animals (e.g., sharks) are still caught

• Dolphins have not recovered

- Too few fish to eat

• Rules and technology have decreased dolphin deaths

Bottom-trawling destroys ecosystems

• Heavy nets crush organisms and damage sea

bottoms

- It is especially destructive to complex areas

(e.g., reefs)

• It equals clear-cutting and strip mining

- Georges Bank has been trawled three times

- Destroying young cod as bycatch

- The reason the cod stock is not recovering

Modern 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

• George Bank cod fishery also collapsed

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Industrialized fishing is destroying fisheries

• Oceans today contain only one-tenth of the large-bodied animals they once did.

• 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

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

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We are “fishing down the food chain”

• Figures on total global catch do 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

- Shifting from large, desirable species to smaller, less desirable ones

- This entails catching species at lower trophic levels

Purchasing 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

- Avoid: Atlantic cod, wild-caught caviar, sharks, farmed salmon

• Best choices: farmed catfish, mussels, oysters, tilapia

Diversity loss erodes ecosystem services

• Factors that deplete biodiversity threaten ecosystem services of 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

Fisheries management

• Based on maximum sustained yield to maximize harvest

- While keeping fish available for the future

- Managers may limit the harvest or restrict gear used

• Despite management, stocks have plummeted

- It is time to rethink fisheries management

• 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

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, recreation fishers, and businesses do not support reserves

- Be sensitive to concerns of local residents

Reserves work for both fish and fisheries

• Marine reserves:

Ch. 16 Notes APES

15

- 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

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

• Local residents who were opposed support reserves once they see their benefits

• Once commercial trawling was stopped on Georges Bank:

- Populations of organisms began to recover

- Fishing in adjacent waters increased

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 in coming up with answers

Conclusions

• 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