Sustaining Aquatic

Biodiversity

Chapter 12

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

Salinity of the Oceans

Mapping the Trends

• 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

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

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

Trawling

• 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

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).

Fig. 12-11, p. 267

• Deliver nutrients to sea to help sustain coastal

fisheries

• Deposit silt that maintains deltas

• Purify water

• Renew and renourish wetlands

• Provide habitats for wildlife

Natural Capital

Ecological Services of Rivers