Aquatic Biodiversity

Chapter 8

Core Case Study: Why Should We Care about Coral Reefs? (1)

Biodiversity

Formation

Important ecological and economic services• Moderate atmospheric temperatures• Act as natural barriers protecting coasts from

erosion• Provide habitats• Support fishing and tourism businesses• Provide jobs and building materials• Studied and enjoyed

Core Case Study: Why Should We Care about Coral Reefs? (2)

Degradation and decline• Coastal development• Pollution• Overfishing• Warmer ocean temperatures leading to coral

bleaching• Increasing ocean acidity

A Healthy Coral Reef in the Red Sea

8-1 What Is the General Nature of Aquatic Systems?

Concept 8-1A Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface with oceans dominating the planet.

Concept 8-1B The key factors determining biodiversity in aquatic systems are temperature, dissolved oxygen content, availability of food and availability of light and nutrients necessary for photosynthesis.

Most of the Earth Is Covered with Water (1)

Saltwater: global ocean divided into 4 areas• Atlantic• Pacific• Arctic• Indian

Freshwater

Most of the Earth Is Covered with Water (2)

Aquatic life zones• Saltwater: marine • Oceans and estuaries• Coastlands and shorelines• Coral reefs• Mangrove forests

• Freshwater• Lakes• Rivers and streams• Inland wetlands

The Ocean Planet

Fig. 8-2, p. 163

Ocean hemisphere Land–ocean hemisphere

Distribution of the World’s Major Saltwater and Freshwater Sources

Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water (1)

Plankton• Phytoplankton• Zooplankton• Ultraplankton

Nekton

Benthos

Decomposers

Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water (2)

Key factors in the distribution of organisms• Temperature• Dissolved oxygen content• Availability of food• Availability of light and nutrients needed for

photosynthesis in the euphotic, or photic, zone

8-2 Why Are Marine Aquatic Systems Important?

Concept 8-2 Saltwater ecosystems are irreplaceable reservoirs of biodiversity and provide major ecological and economic services.

Oceans Provide Important Ecological and Economic Resources

Reservoirs of diversity in three major life zones• Coastal zone• Usually high NPP

• Open sea• Ocean bottom

Major Ecological and Economic Services Provided by Marine Systems

Fig. 8-4, p. 165

Marine Ecosystems

Economic Services

Climate moderation Food

CO2 absorption Animal and pet feed

Nutrient cycling Pharmaceuticals

Harbors and transportation routes

Waste treatment

Reduced storm impact (mangroves, barrier islands, coastal wetlands)

Coastal habitats for humans

RecreationHabitats and nursery areas Employment

Genetic resources and biodiversity

Oil and natural gas

Minerals

Scientific information Building materials

Ecological Services

NATURAL CAPITAL

Natural Capital: Major Life Zones and Vertical Zones in an Ocean

Fig. 8-5, p. 166

Low tideCoastal Zone

Open Sea

Depth in meters

High tideSun

Sea level

50Estuarine Zone

Euphotic Zone

100

Ph

oto

syn

thes

is

Continental shelf

200

Bathyal Zone 500

1,000

Tw

ilig

ht

1,500

Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline .

Abyssal Zone

2,000

3,000

4,000

Dar

knes

s

5,000

10,000

0 5 10 15 20 25 30

0

Water temperature (°C)

Estuaries and Coastal Wetlands Are Highly Productive (1)

Estuaries and coastal wetlands • River mouths• Inlets• Bays• Sounds• Salt marshes• Mangrove forests

Seagrass Beds• Support a variety of marine species• Stabilize shorelines• Reduce wave impact

Estuaries and Coastal Wetlands Are Highly Productive (2)

Important ecological and economic services• Coastal aquatic systems maintain water quality

by filtering• Toxic pollutants• Excess plant nutrients• Sediments

• Absorb other pollutants • Provide food, timber, fuelwood, and habitats• Reduce storm damage and coast erosion

View of an Estuary from Space

Some Components and Interactions in a Salt Marsh Ecosystem in a Temperate Area

Fig. 8-7a, p. 167

Herring gulls Peregrine falcon

Snowy egret Cordgrass

Short-billed dowitcher

Marsh periwinkle

PhytoplanktonSmelt

Zooplankton and small crustaceans

Soft-shelled clam

ClamwormBacteria

Producer to primary consumer

Primary to secondary consumer

Secondary to higher-level consumer

All consumers and producers to decomposers

Fig. 8-7b, p. 167

Mangrove Forest in Daintree National Park in Queensland, Australia

Rocky and Sandy Shores Host Different Types of Organisms

Intertidal zone• Rocky shores• Sandy shores: barrier beaches

Organism adaptations necessary to deal with daily salinity and moisture changes

Importance of sand dunes

Living between the Tides

Fig. 8-9, p. 169

Rocky Shore Beach

Sea star Hermit crab Shore crab

High tide

Periwinkle

Sea urchin AnemoneMussel

Low tideSculpin

Barnacles

Kelp Sea lettuce

Monterey flatwormBeach fleaNudibranch

Peanut worm Tiger beetle

Barrier Beach

Blue crab ClamDwarf olive

High tide

SandpiperGhost shrimpSilversides Low tide Mole

shrimp

White sand macoma

Sand dollar

Moon snail

Beach flea

Peanut worm Tiger beetle

Barrier Beach Blue crab ClamDwarf olive

High tide

SandpiperGhost shrimpSilversides Low tide Mole

shrimp

White sand macoma

Sand dollar

Moon snail

Fig. 8-9, p. 169

Rocky Shore BeachSea star Hermit

crab Shore crab

High tide

Periwinkle

Sea urchin AnemoneMussel

Low tideSculpin

Barnacles

KelpSea lettuce

Monterey flatworm

Nudibranch

Stepped Art

Primary and Secondary Dunes

Fig. 8-10, p. 170

Ocean Beach Primary Dune

Trough Secondary Dune

Back Dune Bay or Lagoon

Recreation, no building

Walkways, no building

Limited recreation and

walkways

Walkways, no building

Most suitable for development

Recreation

Grasses or shrubs

Bay shore

Taller shrubsTaller shrubs and trees

Coral Reefs Are Amazing Centers of Biodiversity

Marine equivalent of tropical rain forests

Habitats for one-fourth of all marine species

Natural Capital: Some Components and Interactions in a Coral Reef Ecosystem

Fig. 8-11, p. 171

Gray reef shark

Sea nettle

Green sea turtle

Blue tang

Fairy bassletParrot fish

Sergeant major

Hard corals Algae Brittle star

Banded coral shrimpPhytoplankton

Symbiotic algae

Coney

Coney

ZooplanktonBlackcap basslet

Sponges

Moray eel

Bacteria

Producer to primary consumer

Primary to secondary consumer

Secondary to higher-level consumer

All consumers and producers to decomposers

The Open Sea and Ocean Floor Host a Variety of Species

Vertical zones of the open sea• Euphotic zone• Bathyal zone• Abyssal zone: receives marine snow• Deposit feeders• Filter feeders

• Upwellings

Primary productivity and NPP

Animation: Ocean provinces

Video: Elephant seals

Video: Florida reefs

Video: Giant clam

Video: Reef fish (Bahamas)

Video: Schooling fish

Video: Sea anemones

Video: Sea lions

Video: Sting rays

8-3 How Have Human Activities Affected Marine Ecosystems?

Concept 8-3 Human activities threaten aquatic biodiversity and disrupt ecological and economic services provided by saltwater systems.

Human Activities Are Disrupting and Degrading Marine Systems

Major threats to marine systems • Coastal development• Overfishing• Runoff of nonpoint source pollution• Point source pollution• Habitat destruction• Introduction of invasive species• Climate change from human activities• Pollution of coastal wetlands and estuaries

Case Study: The Chesapeake Bay—an Estuary in Trouble (1)

Largest estuary in the US; polluted since 1960

Population increased

Point and nonpoint sources raised pollution

Phosphate and nitrate levels too high

Case Study: The Chesapeake Bay—an Estuary in Trouble (2)

Overfishing

1983: Chesapeake Bay Program• Update on recovery of the Bay• Should we introduce an Asian oyster?

Chesapeake Bay

Video: ABC News: Beach pollution

8-4 Why Are Freshwater Ecosystems Important?

Concept 8-4 Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.

Water Stands in Some Freshwater Systems and Flows in Others (1)

Standing (lentic) bodies of freshwater• Lakes• Ponds• Inland wetlands

Flowing (lotic) systems of freshwater• Streams• Rivers

Water Stands in Some Freshwater Systems and Flows in Others (2)

Formation of lakes

Four zones based on depth and distance from shore• Littoral zone• Limnetic zone• Profundal zone• Benthic zone

Major Ecological and Economic Services Provided by Freshwater Systems

Fig. 8-14, p. 174

NATURAL CAPITAL

Freshwater Systems

Ecological Services

Economic Services

Climate moderation Food

Nutrient cyclingDrinking water

Waste treatmentIrrigation water

Flood control

HydroelectricityGroundwater recharge

Habitats for many species

Transportation corridors

Genetic resources and biodiversity

Recreation

Scientific information Employment

Distinct Zones of Life in a Fairly Deep Temperate Zone Lake

Fig. 8-15, p. 175

Sunlight

Painted turtle

Blue-winged teal

Green frog

Muskrat

Pond snail Littoral zone Plankton

Limnetic zoneProfundal zoneDiving beetle Benthic zone

Northern pike

Yellow perch Bloodworms

Some Lakes Have More Nutrients Than Others

Oligotrophic lakes• Low levels of nutrients and low NPP

Eutrophic lakes• High levels of nutrients and high NPP

Mesotrophic lakes

Cultural eutrophication leads to hypereutrophic lakes

The Effect of Nutrient Enrichment on a Lake

Fig. 8-16a, p. 175

Stepped Art

Freshwater Streams and Rivers Carry Water from the Mountains to the Oceans

Surface water

Runoff

Watershed, drainage basin

Three aquatic life zones • Source zone• Transition zone• Floodplain zone

Three Zones in the Downhill Flow of Water

Fig. 8-17, p. 176

LakeGlacierRain and

snowRapids

WaterfallTributary

Flood plainOxbow lake

Salt marsh

Delta Deposited sediment

Source ZoneOcean

Transition Zone

WaterSediment

Floodplain Zone

Waterfall

LakeGlacierRain and

snowRapids

Source Zone

Fig. 8-17, p. 176

Transition Zone

Tributary

Flood plainOxbow lake

Salt marsh

Delta Deposited sediment

Ocean

WaterSediment

Floodplain Zone

Stepped Art

Case Study: Dams, Deltas, Wetlands, Hurricanes, and New Orleans

Coastal deltas, mangrove forests, and coastal wetlands: natural protection against storms

Dams and levees reduce sediments in deltas: significance?

New Orleans, Louisiana, and Hurricane Katrina: August 29, 2005

Global warming, sea rise, and New Orleans

New Orleans, Louisiana, (U.S.) and Hurricane Katrina

Projection of New Orleans if the Sea Level Rises 0.9 Meter

Freshwater Inland Wetlands Are Vital Sponges (1)

Marshes

Swamps

Prairie potholes

Floodplains

Arctic tundra in summer

Freshwater Inland Wetlands Are Vital Sponges (2)

Provide free ecological and economic services• Filter and degrade toxic wastes• Reduce flooding and erosion• Help to replenish streams and recharge

groundwater aquifers• Biodiversity• Food and timber• Recreation areas

Active Figure: Lake zonation

Animation: Lake turnover

Animation: Trophic natures of lakes

Video: River flyover

8-5 How Have Human Activities Affected Freshwater Ecosystems?

Concept 8-5 Human activities threaten biodiversity and disrupt ecological and economic services provided by freshwater lakes, rivers, and wetlands.

Human Activities Are Disrupting and Degrading Freshwater Systems

Impact of dams and canals on rivers

Impact of flood control levees and dikes along rivers

Impact of pollutants from cities and farms on rivers

Impact of drained wetlands

Case Study: Inland Wetland Losses in the United States

Loss of wetlands has led to• Increased flood and drought damage

Lost due to• Growing crops• Mining• Forestry• Oil and gas extraction• Building highways• Urban development