This lecture will help you understand:

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Slides prepared by Jay Withgott and Heidi Marcum

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Ch 16Marine and Coastal Systems: Resources, Impacts, and Conservation

Part 2: Environmental Issues the Search for Solutions


This lecture will help you understand:

• The marine environment• Major marine ecosystems• Human uses of marine

resources• Human impacts on the

marine environment• The state of ocean

fisheries• Marine protected areas

and reserves


Central Case: collapse of the cod fisheries

• No fish has more impact on human civilization than the Atlantic cod

• Eastern Canadians and U.S. fishermen have fished for cod for centuries

• Large ships and technology have destroyed the cod fishery

• Even protected stocks are not recovering- Prey may now be competing with,

and eating, young cod


Cod are groundfish

• They live or feed along the bottom

- Halibut, pollock, flounder• Cod eat small fish and invertebrates• They grow to 60-70 cm long and

can live 20 years• Inhabit cool waters on both sides of

the Atlantic• There are 24 stocks (populations) of

cod


Oceans cover most of the Earth’s surface• The oceans influence global climate, team with

biodiversity, facilitate transportation and commerce, and provide resources for us

• They cover 71% of Earth’s surface and contain 97% of Earth’s surface water

• Oceans influence the atmosphere, lithosphere, and biosphere


The oceans contain more than water

• Ocean water is 96.5% water - Plus, ions of dissolved salts

• Evaporation removes pure water and leaves a higher concentration of salt

• Nutrients (nitrogen and phosphorus)

• Dissolved gas- Oxygen is added by plants,

bacteria, and atmospheric diffusion


Ocean water is vertically structured

• Temperature declines with depth• Heavier (colder saltier) water sinks

- Light (warmer and less salty) water remains near the surface

• Temperatures are more stable than land temperatures- Water’s high heat capacity - It takes much more heat to warm water than air

• Oceans regulate the earth’s climate - They absorb and release heat- Ocean’s surface circulation


The ocean has several layers• Surface zone

- Warmed by sunlight and stirred by wind

- Consistent water density• Pycnocline = below the surface zone

- Density increases rapidly with depth

• Deep Zone = below the pycnocline- Dense, sluggish water - Unaffected by winds, storms,

sunlight, and temperature


Ocean water flows horizontally in currents

• Currents = the ocean is composed of vast riverlike flows - Driven by density differences, heating and cooling,

gravity, and wind - Influence global climate and El Niño and La Niña- Transport heat, nutrients, pollution, and the larvae of

many marine species• Some currents such as the Gulf Stream are rapid and

powerful- The warm water moderates Europe’s climate


The upper waters of the oceans flow in currents


Surface winds and heating create vertical currents • Upwelling = the vertical flow of cold, deep water towards the

surface

- High primary productivity and lucrative fisheries- Also occurs where strong winds blow away from, or

parallel to, coastlines • Downwellings = oxygen-rich water sinks where surface currents

come together


Seafloor topography can be rugged and complex

• The seafloor consists of…- Underwater volcanoes- Steep canyons- Mountain range

- The planet’s longest range is under water

- Mounds of debris- Trenches- Some flat areas


Understanding underwater geography

• Maps show…- Bathymetry = the measurement of ocean depths- Topography = the physical geography or the shape

and arrangement of landforms• Continental shelves = gently sloping areas that underlie

the shallow waters bordering continents• Shelf-slope break = sudden drop off of the continental

shelf• Continental slope = connects the continental shelf to the

ocean floor


A stylized bathymetric profile of the ocean


Regions of ocean differ greatly

• Some zones support more life than others• Photic zone = well-lighted top layer that supports high

primary productivity• Pelagic = habitats and ecosystems occurring between the

ocean’s surface and floor• Benthic = habitats and ecosystems occurring on the

ocean floor


Open ocean systems vary in biodiversity• Microscopic phytoplankton

constitute the base of the marine food chain in the pelagic zone - Algae, protists, and

cyanobacteria• These organisms feed

zooplankton- Which then feeds fish,

jellyfish, whales, etc.• Predators at higher trophic levels

include larger fish, sea turtles, sharks, and fish-eating birds


Animals of the deep ocean• Animals adapt to extreme water

pressure and the absence of light- Scavenge carcasses or organic

detritus- Some are predators, while

others have mutualistic relationships with bacteria

- Some species carry bacteria that produce light chemically by bioluminescence

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


Kelp forests harbor many organisms• Kelp = large, dense, brown algae growing from the floor of

continental shelves • Dense strands form kelp forests along temperate coasts• Shelter and food for organisms• Absorbs wave energy and protects shorelines from erosion• Eaten by people• Alginates serve as thickeners in cosmetics, paints, paper, and

soaps


Coral reefs are treasure troves of biodiversity

• Located in shallow subtropical and tropical waters• Corals = tiny colonial marine organisms

- Related to sea anemones and jellyfish- Remain attached to rock or existing reef and

capture passing food with stinging tentacles- Derive nourishment from symbiotic algae,

zooxanthallae


Coral reefs consist of millions of corals

• Coral reef = a mass of calcium carbonate composed of the skeletons of corals- Consists of millions of densely packed individuals- Protect shorelines by absorbing waves- Innumerable invertebrates and fish species find food and

shelter in reef nooks and crannies


Coral reefs are in worldwide decline• Coral bleaching = occurs when zooxanthellae leave the coral

- Coral lose their color and die, leaving white patches- From climate change, pollution, or unknown natural causes

• Nutrient pollution causes algal growth, which covers coral• Divers damage reefs by using cyanide to capture fish• Acidification of oceans deprives corals of necessary carbonate

ions for their structural parts


Deepwater coral reefs exist

• They thrive in waters outside the tropics - On ocean floor at depths of 200-500 m (650-1650 ft)

• Occur in cold-water areas• Little is known about these reefs• Already, many have been badly damaged by trawling

- Some reefs are now being protected


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


Intertidal zones are a tough place to live

• But they have remarkable diversity- Rocky shorelines, crevices,

pools of water (tide pools)- Anemones, mussels, barnacles,

urchins, sea slugs, starfish, and crabs

• Temperature, salinity, and moisture change dramatically from high to low tide- Sandy intertidal zones have

slightly less biodiversity


Salt marshes occur widely

• Salt marsh = occur along coasts at temperate latitude- Tides wash over gently sloping, sandy, silty

substrates- High primary productivity- Critical habitat for birds and commercial fish and

shellfish species- Filter pollution- Stabilize shorelines against storm surges


People have changed and destroyed salt marshes

• People have altered or destroyed salt marshes for development- We lose key ecosystem service- Flooding worsens


Mangrove forests line coasts• In tropical and subtropical latitudes

- Replace salt marshes along sandy coasts

• Mangroves = trees with unique roots- Curve upwards for oxygen- Curve downwards for support

• Nurseries for commercial fish and shellfish

• Nesting areas for birds• Food, medicine, tools, construction

materials


Mangrove forests have been destroyed

• Development for residential, commercial, and recreational uses

• Shrimp farming• Half the world’s mangrove forests are gone• Once destroyed, coastal areas no longer

- Slow runoff- Filter pollutants- Retain soil- Protect communities against storm surges

• We are protecting only 1% of remaining mangroves


Estuaries: where fresh and salt water meet

• Estuaries = water bodies where rivers flow into the ocean- Wide fluctuations in salinity

• Critical habitat for shorebirds and shellfish• Transitional zone for anadromous (spawn in freshwater,

mature in salt water) fishes• Affected by development, pollution, habitat alteration,

and overfishing


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


We extract energy from oceans

• Crude oil and natural gas - Oil spills damage fisheries

• Methane hydrate = a potential energy source- Ice-like solid methane

embedded in water crystals- A vast supply, but research

needs to be done• Renewable energy sources, such as

waves, tides, heat


We extract minerals from oceans

• Minerals such as sand, gravel, sulfur, calcium carbonate, and silica

• Rich deposits of copper, zinc, silver, and gold• Manganese nodules are scattered along the ocean’s floor

- But, they are too hard to currently mine


Marine pollution threatens resources

• Even into the mid-20th century, coastal U.S. cities dumped trash and untreated sewage along their shores

• Oil, plastic, chemicals, excess nutrients make their way from land into oceans

• Raw sewage and trash from cruise ships• Abandoned fishing gear from fishing boats

In 2006, 359,000 Ocean Conservancy volunteers from 66 nations picked up 3.2 million kg (7 million lbs.) of trash


Nets and plastic debris endangers marine life • Plastic items dumped into the

sea harm or kill wildlife• Plastic is non-biodegradable

- Drifts for decades- Washes up on beaches- Wildlife eat it or get

entangled and die• Marine debris affects people

- Equipment damage• The 2006 Marine Debris

Research, Prevention and Reduction Act


Oil pollution comes from spills of all sizes

• Major oils spills (i.e., the Exxon Valdez) make headlines and cause serious environmental problems

• Most pollution comes from small sources- Boat leakage and runoff from

land- Naturally occurring leaks from

the seabed• Oil spills coat and poison wildlife


Oil pollution has decreased

• Governments have implemented more stringent regulations

• The U.S. Oil Pollution Act of 1990 - Creates a $1 billion prevention

and cleanup fund - Requires all ships have double

hulls by 2015• Recently, oil spills have decreased

- The oil industry resists such safeguards


Toxic pollutants contaminate seafood

• Mercury contamination- From coal combustion and other sources- Bioaccumulates and biomagnifies- Dangerous to young children and pregnant or nursing

mothers- Avoid eating swordfish, shark, and albacore tuna- Eat seafood low in mercury (catfish, salmon, canned

light tuna)• Avoid seafood from areas where health advisories have

been issued


Excess nutrients cause algal blooms

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

• Red tide = algal species produce reddish pigments that discolor water- Illness and death to wildlife and

humans- Economic losses to fishing

industries and beach tourism• Reduce runoff and prevent

consumption of affected organisms


Emptying the oceans

• We are placing unprecedented pressure on marine resources- Half the world’s marine fish populations are fully

exploited- 25% of fish population are overexploited and

heading to extinction• Total fisheries catch leveled off after 1998, despite

increased fishing effort- It is predicted that populations of all ocean species

we fish for today will collapse by the year 2048


The total global fisheries catch has increased


We have long overfished

• People began depleting sea life centuries ago• Some species hunted to extinction: Steller’s sea cow,

Atlantic gray whale, Caribbean monk seal• Overharvesting of Chesapeake Bay oyster beds led to

the collapse of its fishery, eutrophication, and hypoxia

• Decreased sea turtle populations causes overgrowth of sea grass and can cause sea grass wasting disease

• People never imagined that groundfish could be depleted- New approaches or technologies increased catch

rates


Fishing has industrialized

• Factory fishing = highly industrialized, huge vessels use powerful technologies to capture fish in huge volumes

- Even process and freeze their catches while at sea• Driftnets for schools of herring, sardines, mackerel, sharks• Longline fishing for tuna and swordfish • Trawling for pelagic fish and groundfish


Fishing practices kill nontarget animals

• By-catch = the accidental capture of animals

• Driftnetting drowns dolphins, turtles, and seals- Fish die from air exposure on deck- Banned or restricted by many nations

• Longline fishing kills turtles, sharks, and albatrosses- 300,000 seabirds die each year

• Bottom-trawling destroys communities- Likened to clear-cutting and strip

mining


Modern fishing fleets deplete marine life rapidly• Grand Banks cod have been fished for centuries• Catches more than doubled with immense industrial

trawlers- Record-high catches lasted only 10 years


Industrialized fishing depletes populations

• Catch rates drop precipitously with industrialized fishing- 90% of large-bodied fish and sharks are eliminated

within 10 years- Populations stabilize at 10% of their former levels

• Marine communities may have been very different before industrial fishing- Removing animals at higher trophic levels allows

prey to proliferate and change communities


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


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 less-

fished portions of the ocean- Fleets spend more time fishing and have been

setting out more nets and lines, increasing effort to catch the same number of fish

- Improved technologies: faster ships, sonar mapping, satellite navigation, thermal sensing, aerial spotting

- Data supplied to international monitoring agencies may be false


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


Consumer choices influence fishing practices

• Buy ecolabeled seafood- Dolphin-safe tuna

• Consumers don’t know how their seafood was caught- Nonprofit organizations have

devised guides for consumers- Best choices: farmed catfish and

caviar, sardines, Canadian snow crab- Avoid: Atlantic cod, wild-caught

caviar, sharks, farmed salmon


Fisheries management• Based on maximum sustained yield

- Maximal harvest while keeping fish available for the future

- Managers may limit the harvested or restrict gear used• Despite management, stocks have plummeted

- It is time to rethink fisheries management• Ecosystem-based management

- Shift away from species and toward the larger ecosystem

- Consider the impacts of fishing on habitat and species interactions

- Set aside areas of oceans free from human interference


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


Reserves work for both fish and fisheries

• Found that reserves do work as win-win solutions • Overall benefits included…

- Boosting fish biomass- Boosting total catch- Increasing fish size

• Benefits inside reserve boundaries included…- Rapid and long-term increases in marine organisms- Decrease mortality and habitat destruction- Lessen the likelihood of extirpation of species


Areas outside reserves also benefit

• Benefits included…- A “spillover effect” when individuals of protected

species spread outside reserves- Larvae of species protected within reserves “seed the

seas” outside reserves- Improved fishing and ecotourism


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


Conclusion

• Oceans cover most of our planet and contain diverse topography and ecosystems

• We are learning about the oceans and coastal environments, intensifying our use their resources and causing severe impacts

• Setting aside protected areas of the ocean can serve to maintain natural systems and enhance fisheries

• We may once again attain the ecological systems that once flourished in our waters


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


QUESTION: ReviewThe area of an ocean that contains open water that receives sunlight is called the _______zone.

a) Littoralb) Photicc) Pelagicd) Benthic


QUESTION: Review_____ is defined as “large, dense, brown algae growing

from the floor of continental shelves.” a) Coralb) Red tidec) Bottomfishd) Kelp


QUESTION: ReviewCoral bleaching occurs when ….

a) Corals reproduceb) Fish move into coral reefsc) Zooxanthellae leave the corald) Coral reefs expand their range


QUESTION: ReviewAn area where rivers flow into the ocean is called a(n) …?

a) Estuaryb) Mangrove swampc) Salt marshd) Coral reef


QUESTION: ReviewWhich of the following does not mask the decline of

fisheries?

a) Fishing fleets travel longer distancesb) Fishing fleets spend more time fishingc) Fishing fleets use traditional methods of fishingd) Data supplied to monitoring agencies may be false


QUESTION: ReviewMarine reserves have all the following benefits except:

a) Fishing increases in the reserveb) The size of fish increasesc) Larvae can “seed” areas outside the reserved) Decreased mortality and habitat destruction


QUESTION: Interpreting Graphs and Data

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

a) China will be a major player in applying fishing pressure

b) China will be player a smaller role in applying fishing pressure

c) The world will decrease its fishing pressure

d) The U.S. is not included in this graph


QUESTION: Interpreting Graphs and DataWhich conclusion can you draw from this graph?

a) Oceans today contain far fewer fish

b) Oceans today contain far more fish

c) It is easier to find fish todayd) There is little correlation

between fishing and fish stocks


QUESTION: ViewpointsIf a developer wants to build a community on an

estuary, providing jobs but eliminating the marsh, what should be done?

a) Let the developer build; we need the jobsb) Let the developer build, but make him/her pay

for any damage from stormsc) Let the surrounding landowners vote whether

to let the developer buildd) Prevent the development; the potential

damage is too great


QUESTION: ViewpointsDo you plan to alter your decisions about eating

seafood?

a) Yes; I will be more selective about what I eatb) No; I will continue to eat the same type and

amount of seafood as always

Documents

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