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
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
• Salinity Map
Distribution of Sea Salinity 1. Using colored pencils, create a legend
by choosing a different color for each salinity value on your isohaline map. (ppt)
2. Name the continents and countries.
3. Using your color key, fill in the regions of the ocean that correspond to the different surface water salinity values
4. Answer the accompanying questions. This lab will be graded on ACCURACY, not completion.
Questions
1. List the ocean regions with the highest
sea surface salinity.
2. List the ocean regions with lowest sea
surface salinity.
3. Describe the distribution of sea surface
salinity patterns as a function of
latitude.
4. Describe the distribution of sea surface
salinity patterns as a function of
surface currents.
Questions (continued)
5. What are the major ions
contributing to ocean salinity and
their relative abundances?
6. What is the impact from rising
ocean surface temperatures to the
organisms in the euphotic zone?
Be detailed and relate your answer
to salinity.
Review: Principles of
Sustainability
1. Reliance on solar energy
2. Biodiversity
3. Population Control
4. Nutrient Recycling
Economic Importance of
Aquatic Ecosystems
• The economic importance of aquatic
diversity is the estimate of the value
of their ecological services which is
$21 trillion a year.
• At least 3.5 billion people depend on
the seas for their primary source of
food; this number could double to 7
billion in 2025.
What is aquatic
biodiversity?
• Aquatic biodiversity refers to the
composition of plants and animals
in the fresh and salt waters of the
planet.
– Freshwater
– Saltwater
– Wetlands, Estuaries
Ocean Biodiversity
• We have only explored only 5% of
our oceans and know very little
about it’s biodiversity
• Human activities are undermining
aquatic biodiversity by destroying
and degrading coastal wetlands,
coral reefs, seagrass beds, kelp
beds, mangroves and the ocean
bottom.
Marine Ecological Services
• Many medicines have been
developed from sea organisms:
sponges, anemones, puffer fish,
porcupine fish, seaweeds, etc.
• The waters are used for extensive
recreational activities, and mention
commercial transportation.
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
• 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
Human Impact on Aquatic
Biodiversity
• Human impact on aquatic
biodiversity can be summarized as:
– H: Habitat Loss
– I: Invasive Species
– P: Population Growth
– P: Pollution
– O: Overfishing (extinction)
Loss of Habitat
• Loss of habitat can be intentional
such as the destruction of wetlands
or estuarine environments, it can
also be an effect from pollution
Invasive Species
• Invasive species are introduced to
water in ports and off-shore from
ballast water
– zebra mussels
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
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
• 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 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 pollution has decreased • Governments have
implemented more stringent
regulations
• The U.S. Oil Pollution Act of
1990
– Creates a $1 bil prevention
and cleanup fund
– Requires all ships have double
hulls by 2015
• Recently, oil spills have
decreased even though 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
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
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
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
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
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
Overfishing and Extinction:
Gone Fishing, Fish Gone
• About 75% of the world’s commercially
valuable marine fish species are over
fished or fished near their sustainable
limits.
– Big fish are becoming scarce.
– Smaller fish are next.
– We throw away 30% of the fish we catch.
– We needlessly kill sea mammals and birds.
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
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
PROTECTING AND
SUSTAINING MARINE
BIODIVERSITY • Six of the world’s
seven major
turtle species
are threatened
or endangered
because o
human
activities.
Figure 12-4
Case Study: The Florida
Manatee and Water Hyacinths
• Manatee can eat
unwanted Water
Hyacinths.
• Endangered due to:
– Habitat loss.
– Entanglement from
fishing lines and nets.
– Hit by speed boats.
– Stress from cold.
– Low reproductive rate
Figure 12-B
Case Study: Commercial
Whaling • After many of
the world’s
whale species
were
overharvested,
commercial
whaling was
banned in
1960, but the
ban may be
overturned. Figure 12-6
Case Study:
Commercial
Whaling • Despite ban, Japan,
Norway, and Iceland kill
about 1,300 whales of
certain species for
scientific purposes.
– Although meat is still sold
commercially.
Figure 12-5
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
To Protect and Serve • We can protect and sustain marine
biodiversity by using laws,
international treaties, and
education.
– First identify and protect species that
are endangered and/or threatened.
– Clean up aquatic environments
Why is it so hard?
1. Our human footprint is so large
and is growing exponentially;
2. Damage to the ocean is not
usually visible to the naked eye;
3. People view the ocean as an in-
exhaustable resource;
4. The ocean is outside the legal
jurisdiction of any one country.
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 (less than 0.3% of the ocean)
– Leave ecosystems intact, without human
interference
– Improve fisheries, because young fish will
disperse into surrounding areas
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 and decrease mortality and habitat
destruction
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
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
Marine Management
• There are a number of ways to
manage marine fisheries more
sustainably and protect marine
biodiversity.
– A country has jurisdiction over the ocean
up to 200 miles from it’s coast.
– Rather than protecting the marine
environment, countries tend to promote
fishing.
Integrated Coastal
Management
• Integrated Coastal Management
(ICM) is an idea or management
policy based on a community
approach.
– Private sector as well as the public
sector work together to identify
problems and share the burden of
restoration or management.
Managing Fisheries
• Fishery Regulations:
– set catch limits well beyond maximum
sustainable yield
– improve monitoring and enforcement
• Economic Approach:
– reduce or eliminate subsidies
– charge fees for harvesting fish and
shellfish from public areas
– certify sustainable fisheries
More Management
• Protected Areas:
– establish “no-fishing” zones
– establish more reserves
– rely on integrated coastal management
• Consumer Education:
– label sustainably harvested fish
– educate about overfished and
endangered species
Management (cont.)
• Bycatch:
– streamline fishing techniques and tools
• Aquaculture:
– restrict coastal locations for fish farms
– control pollution (CWA)
– depend on herbivorous fish species
• Non-native Invasions:
– kill organisms in ship ballast water,
filter ballast water or dump in open
sea
Legislation: Each group will
discuss the event and the
impact 1946 - International Convention of the
Regulation of Whaling
1970 - US ban on whaling and importation
of whale products
1972 - US Marine Mammel Protection Act
1973 - US Endangered Species Act
1975 - Convention on International Trade
in Endangered Species (CITES)
1979 - Global Treaty on Migratory Species
Freshwater • Freshwater fisheries, lakes and rivers
can be protected, sustained, and even
restored by building and protecting
populations of desirable species, by
prevention of overfishing, and by
decreasing populations of less
desirable species.
– Laws must be enacted and funded to
protect scenic rivers; they must be
protected from development and dam
construction projects.
Case Study: Lake Victoria
• Lake Victoria is a shallow lake in
East Africa
– Before 1980, the lake had 500 species
of unique fish.
– 80% of the fish population was a small
fish known as cichlids which feed on
detritus, zooplankton and algae
– Since 1980, more than 200 species
have become extinct
Cause and Effect of Loss of
Biodiversity
First: Nile perch, a predatory fish, was
introduced to the lake to stimulate
exports and the population exploded
Second: The nutrient runoff from
nearby fields, deforested land and
untreated sewage, as well as a decline
in the cichlids has lead to frequent
algal blooms.
More Factors
Third: An invasive species of water
living plants has blocked the photic
zone which has lead to lower D.O.
Fourth: The populations of Nile
Perch are decreasing because of a
reduction in the smaller feeder fish.
PROTECTING AND
SUSTAINING MARINE
BIODIVERSITY • Fully protected marine reserves make up
less than 0.3% of the world’s ocean area.
– Studies show that fish populations double,
size grows by almost a third, reproduction
triples and species diversity increases by
almost one fourth.
• Some communities work together to
develop integrated plans for managing
their coastal areas.
Revamping Ocean Policy
• Two recent studies called for an overhaul
of U.S. ocean policy and management.
– Develop unified national policy.
– Double federal budget for ocean research.
– Centralize the National Oceans Agency.
– Set up network of marine reserves.
– Reorient fisheries management towards
ecosystem function.
– Increase public awareness.
MANAGING AND SUSTAINING
MARINE FISHERIES
• There are a number of ways to manage
marine fisheries more sustainably and
protect marine biodiversity.
• Some fishing communities regulate fish
harvests on their own and others work
with the government to regulate them.
– Modern fisheries have weakened the ability
of many coastal communities to regulate
their own fisheries.
Fig. 12-7, p. 261
Solutions
Managing Fisheries
Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations
Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries
Protected Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management Consumer Information Label sustainably harvested fish Publicize overfished and threatened species
Bycatch Use wide-meshed nets to allow escape of smaller fish Use net escape devices for sea birds and sea turtles Ban throwing edible and marketable fish back into the sea
Aquaculture Restrict coastal locations for fish farms Control pollution more strictly Depend more on herbivorous fish species
Nonnative Invasions Kill organisms in ship ballast water Filter organisms from ship ballast water Dump ballast water far at sea and replace with deep-sea water
Wetlands
• Wetlands can be protected, sustained,
and restored by government
regulations which prevent wetland loss.
• Destroyed wetlands can, also, be
restored and adequately monitored for
their protection.
• Development can be kept away from
wetland areas and control of nonnative
species needs to be instituted to
prevent invasion into wetlands.
Enforcement Options • Conservation means management of resources
• Preservation means management but you
cannot disturb the area
• Restoration means you return area to the
original condition (not very realistic)
• Remediation is a general term that means
cleaning up (most common term used)
• Mitigation means repairing an affected area,
usually by replacing it somewhere else
(wetlands)
• Reclamation means you are recovering
resources or land from contaminated sites
(recovering metal from electronics)
PROTECTING, SUSTAINING,
AND RESTORING WETLANDS
• Requiring government permits for filling
or destroying U.S. wetlands has slowed
their loss, but attempts to weaken this
protection continue. Figure 12-8
Fig. 12-9, p. 264
Solutions
Protecting Wetlands
Legally protect existing wetlands
Steer development away from existing wetlands
Use mitigation banking only as a last resort
Require creation and evaluation of a new wetland before destroying an
existing wetland
Restore degraded wetlands
Try to prevent and control invasions by nonnative species
Case Study:
Restoring the Florida
Everglades • The world’s largest ecological restoration
project involves trying to undo some of
the damage inflicted on the Everglades
by human activities.
– 90% of park’s wading birds have vanished.
– Other vertebrate populations down 75-95%.
– Large volumes of water that once flowed
through the park have been diverted for
crops and cities.
– Runoff has caused noxious algal blooms.
Restoring the
Florida
Everglades
• The project has
been attempting
to restore the
Everglades and
Florida water
supplies.
Figure 12-10
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS • Lakes are difficult to manage and are
vulnerable to planned or unplanned
introductions of nonnative species.
• For decades, invasions by nonnative
species have caused major ecological
and economic damage to North
America’s Great lakes.
– Sea lamprey, zebra mussel, quagga mussel,
Asian carp.
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS • Dams can provide many human benefits
but can also disrupt some of the
ecological services that rivers provide.
– 119 dams on Columbia River have sharply
reduced (94% drop) populations of wild
salmon.
– U.S. government has spent $3 billion in
unsuccessful efforts to save the salmon.
– Removing hydroelectric dams will restore
native spawning grounds.
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS • We can help sustain freshwater fisheries
by building and protecting populations
of desirable species, preventing over-
fishing, and decreasing populations of
less desirable species.
• A federal law helps protect a tiny fraction
of U.S. wild and scenic rivers from dams
and other forms of development.
– National Wild and Scenic Rivers Act (1968).
Top Related