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Lecture Outlines Chapter 16 Environment: The Science behind the Stories 4th Edition Withgott/Brennan. This lecture will help you understand:. The marine environment Ocean-climate relationships Marine ecosystems Marine pollution The state of ocean fisheries

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Lecture Outlines Chapter 16 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

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Lecture outlines chapter 16 environment the science behind the stories 4th edition withgott brennan

Lecture Outlines

Chapter 16

Environment:The Science behind the Stories

4th Edition

Withgott/Brennan


This lecture will help you understand

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


Central case collapse of the cod fisheries

Central Case: Collapse of the cod fisheries

No fish has had more impact on civilization than the Atlantic cod

Cod have been fished for centuries

Large ships and technology have destroyed the cod fishery

Even protected stocks are not recovering

Young cod are being preyed on

But other species are recovering in protected areas


Cod are groundfish

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 stocks (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 cover most of the Earth’s surface

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

Oceans cover 71% of Earth’s surface and contain 97.5% of its water

Oceans influence the atmosphere, lithosphere, and biosphere


Seafloor topography can be rugged

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

Topographically complex areas serve as habitat and productive fishing grounds


A stylized bathymetric profile of the ocean

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 contains salt

Ocean water is 96.5% 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

Ocean water is vertically structured

Temperature declines 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 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


The ocean has several layers

The ocean has several layers

Surface zone

Warmed by sunlight and stirred by wind

Consistent water density

Pycnocline = below the surface zone

Density increases with depth

Deep zone = below the pycnocline

Dense, sluggish water

Unaffected by winds, storms, sunlight, or temperature


Ocean water flows horizontally in currents

Ocean water flows horizontally in currents

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 Europe’s climate


Currents form patterns across the globe

Currents form patterns across the globe


Vertical movement affects ecosystems

Vertical movement affects ecosystems

Upwelling =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


Currents affect climate

Currents affect 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 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

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 ni o southern oscillation enso

El Niño–Southern Oscillation (ENSO)

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

Decreased pressure in the eastern Pacific triggers El Niño

Warm water flows eastward, suppressing upwellings


Effects of el ni o and la ni a

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

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


Enso el ni o and la ni a

ENSO, El Niño, and La Niña

Normal conditions

El Niño conditions


Climate change is altering the oceans

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 acidic

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

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

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


Open ocean systems vary in biodiversity

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 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

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

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

Coral reefs are treasure troves of biodiversity

Coral reef = 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

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


Coral reefs are in worldwide decline

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

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


Deepwater coral reefs exist

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

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


A typical intertidal zone

A typical intertidal zone


Intertidal zones are a tough place to live

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

Sandy intertidal zones have slightly less biodiversity


Salt marshes line temperate shorelines

Salt marshes line temperate shorelines

Salt marshes = 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 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

Mangrove forests line coasts

In tropical and subtropical latitudes

They replace salt marshes along sandy coasts

Mangroves = 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

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

Fresh and salt water meet 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


Marine pollution

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

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

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

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

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

Major oil spills cause severe environmental and economic problems


Oil spills have decreased

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 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

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

Excess nutrients cause algal blooms

Harmful algal blooms = nutrients increase algae that produce powerful toxins

Red tide = 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

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


The global fisheries catch has increased

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

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 has industrialized

Factory 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

Fishing practices kill nontarget animals

Bycatch = the accidental capture of animals

Drift netting drowns dolphins, turtles, and seals

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 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

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

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

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


Industrialized fishing is destroying fisheries

Industrialized fishing is destroying fisheries

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

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


Several factors mask declines

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


We are fishing down the food chain

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

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

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

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

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

Reserves work for both fish and fisheries

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


Areas outside reserves also benefit

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

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


Conclusion

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


Question review

QUESTION: Review

A “downwelling” is defined as:

The vertical flow of cold, deep water towards the surface

The vertical flow of warm, deep water towards the surface

Oxygen-rich water sinks

Oxygen-poor water sinks


Question review1

QUESTION: Review

The area of an ocean that contains habitats on the ocean floor is called the _______ zone.

Littoral

Photic

Pelagic

Benthic


Question review2

QUESTION: Review

_____ is defined as “a mass of calcium carbonate composed of the skeletons of tiny animals”.

A Coral reef

Red tide

Bottomfish

Kelp


Question review3

QUESTION: Review

Which statement about coral bleaching is correct?

Corals reproduce most efficiently in colder waters.

Fish move into coral reefs and kill them.

c)Zooxanthellae leave the coral due to climate change or pollution.

Coral reefs expand their range after they have been bleached.


Question review4

QUESTION: Review

An area that occurs along coasts at temperate latitudes is called a(n):

Estuary

Mangrove swamp

Salt marsh

Coral reef


Question review5

QUESTION: Review

Which of the following does NOT mask the decline of fisheries?

Fishing fleets travel longer distances to reach less-fished areas.

Fishing fleets spend more time fishing.

Fishing fleets use sophisticated methods of fishing.

Fleets fish in shallower waters nearer coasts.


Question review6

QUESTION: Review

Marine reserves have all the following benefits EXCEPT:

Fishing increases in areas surrounding the reserve.

The size of fish decreases

Larvae can “seed” areas outside the reserve.

Decreased mortality and habitat destruction occur.


Question viewpoints

QUESTION: Viewpoints

What would you think about letting another country fish 10 miles off the U.S. coast?

That’s fine, as long as the fleet paid the United States.

Let them fish, but make them follow the same rules as U.S. fishermen.

Let only U.S. fishermen fish in these waters.

Prevent most fishing – we need to protect the last fish stocks.


Question interpreting graphs and data

QUESTION: Interpreting Graphs and Data

What does this graph show about the future of global fisheries catch?

  • China will apply major fishing pressure.

  • China’s role in fishing pressure will decline.

  • The world will decrease its fishing pressure.

  • The United States is not included in this graph.


Question interpreting graphs and data1

QUESTION: Interpreting Graphs and Data

Which conclusion can you draw from this graph about commercial catches of Atlantic cod?

  • Intensified fishing increased and the fishery crashed.

  • It is easier to find fish today.

  • There is little correlation between fishing and fish stocks.

  • Moratoria will bring the stocks back.


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