Chapter 8

Biodiversity

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

Degradation and decline◦ Coastal

development◦ Pollution◦ Overfishing◦ Warmer ocean

temperatures leading to coral bleaching

◦ Increasing ocean acidity

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

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

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.

Aquatic life zones◦ Saltwater: marine

Oceans –Atlantic, Pacific, Arctic, Indian estuaries Coastlands and shorelines Coral reefs Mangrove forests

◦ Freshwater Lakes Rivers and streams Inland wetlands

Plankton – weakly swimming, free floating◦ Phytoplankton◦ Zooplankton◦ Ultraplankton – photosynthetic bacteria, 70% of

the primary productivity near the ocean surface

Nekton – strongly swimming consumers

Benthos – bottom dwellers,(oysters,clams,worms)

Decomposers- bacteria

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

Saltwater ecosystems are irreplaceable reservoirs of biodiversity and provide major ecological and economic services.

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

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 ◦ River mouths◦ Inlets◦ Bays◦ Sounds◦ Salt marshes◦ Mangrove forests

Seagrass Beds◦ Support a variety of

marine species◦ Stabilize shorelines◦ Reduce wave

impact

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

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

Intertidal zone – area of shoreline between low and high tides◦ Rocky shores-◦ Sandy shores: barrier beaches

Organism must be able to avoid be being swept away or crushed by waves.

Must survive changing levels of salinity

Importance of sand dunes – first line of defense against ravages of the sea

Vertical zones of the open sea◦ Euphotic zone-brightly lit upper zone, 40% of the

world’s photosynthetic activity, nutrient levels low , DO high, predatory fish

◦ Bathyal zone- dimly lit middle zone, smaller fishes◦ Abyssal zone: dark,cold,low DO◦ receives marine snow – dead and decaying

organisms Deposit feeders Filter feeders

◦ Upwellings Primary productivity and NPP /unit area low, but

the seas cover so much of the earth’s surface ,it is the largest contributor to earth’s overall NPP

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

Largest estuary –US Increased population Point/Nonpoint sources High phosphate/nitrate Overfishing 1960 –polluted 1983-Chesapeake Bay

Program

Freshwater ecosystems provide major ecological and economic services and are irreplaceable reservoirs of biodiversity.

Standing (lentic) bodies of freshwater◦ Lakes-vary in size , depth ,nutrient content◦ Ponds◦ Inland wetlands

Flowing (lotic) systems of freshwater◦ Streams◦ Rivers

Formation of lakes

Four zones based on depth and distance from shore◦Littoral zone – near shore, shallow sunlit

waters to the depth at which rooted plants stop growing , high biodiversity

◦Limnetic zone- open, sunlit surface away from shore, sunlight extends to the depth , main source of photosynthesis, microscopic plankton

◦Profundal zone-deep ocean water, very dark, low DO

◦Benthic zone – bottom of the lake, decomposers, detritus feeder nourished by dead matter that falls from littoral zone

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

Oligotrophic lakes◦ Low levels of nutrients and low NPP,

Eutrophic lakes◦ High levels of nutrients and high

Mesotrophic lakes – between the above 2 types

Cultural eutrophication ( human input of nutrients) leads to hypereutrophic lakes

Oligotrophic lakesLow levels of nutrients and low NPP, deep with steep banks. Water supplied by glaciers and mountain streams, crystal clear water

Crater Lake in Oregon

Fig. 8-16a, p. 175

Stepped Art

NPP- shallow, murky brown or green water with high turbidity.

Lake in Western New York State

The Effect of Nutrient Enrichment on a Lake

Surface water-precipitation that does not sink into the ground

Runoff – flows into stream

Watershed, drainage basin – land area that delivers runoff, sediment, dissolved substances

Three aquatic life zones ◦ Source zone – head waters, clear cold, fast

flowing ◦ Transition zone wider, deeper, warmer streams◦ Floodplain zone – flow across flat valleys, higher

temperatures, muddy, high concentrations of silt

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

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

Marshes – dominated by grasses and weeds

Swamps - dominated by trees and shrubs

Prairie potholes- depressions carved ot by ancient glaciers

Floodplains- excess water during heavy rains and floods

Arctic tundra in summer -

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

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

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

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