Chapter 6 Aquatic Biodiversity. Chapter Overview Questions What are the basic types of aquatic life zones and what factors influence the kinds of life

Chapter 6Chapter 6

Aquatic BiodiversityAquatic Biodiversity

Chapter Overview QuestionsChapter Overview Questions

What are the basic types of aquatic life zones What are the basic types of aquatic life zones and what factors influence the kinds of life and what factors influence the kinds of life they contain?they contain?

What are the major types of saltwater life What are the major types of saltwater life zones, and how do human activities affect zones, and how do human activities affect them?them?

What are the major types of freshwater life What are the major types of freshwater life zones, and how do human activities affect zones, and how do human activities affect them?them?

Why Should We Care About Coral Why Should We Care About Coral Reefs?Reefs?

Coral reefs form in Coral reefs form in clear, warm coastal clear, warm coastal waters of the tropics waters of the tropics and subtropics.and subtropics. Formed by massive Formed by massive

colonies of polyps.colonies of polyps.

Figure 6-1Figure 6-1

Fig. 6-1a, p. 126

Why Should We Care About Coral Why Should We Care About Coral Reefs?Reefs?

Help moderate atmospheric temperature by Help moderate atmospheric temperature by removing COremoving CO22 from the atmosphere. from the atmosphere.

Act as natural barriers that help protect 14% Act as natural barriers that help protect 14% of the world’s coastlines from erosion by of the world’s coastlines from erosion by battering waves and storms.battering waves and storms.

Provide habitats for a variety of marine Provide habitats for a variety of marine organisms.organisms.

AQUATIC ENVIRONMENTSAQUATIC ENVIRONMENTS Saltwater and freshwater aquatic life zones cover Saltwater and freshwater aquatic life zones cover

almost three-fourths of the earth’s surfacealmost three-fourths of the earth’s surface Major types of organisms found in aquatic Major types of organisms found in aquatic

environments depends on salinityenvironments depends on salinity Salinity: amount of various salts dissolved in a given Salinity: amount of various salts dissolved in a given

volume of watervolume of water Two main types of aquatic life zones:Two main types of aquatic life zones:

Marine (saltwater): estuaries, coastlines, coral Marine (saltwater): estuaries, coastlines, coral reefs, costal marshes, mangrove swamps, and reefs, costal marshes, mangrove swamps, and oceansoceans

Freshwater: lakes, ponds, streams, rivers, and Freshwater: lakes, ponds, streams, rivers, and inland wetlandsinland wetlands


Fig. 6-2, p. 127

Land–ocean hemisphereOcean hemisphere

AQUATIC ENVIRONMENTSAQUATIC ENVIRONMENTS


What Kinds of Organisms Live in What Kinds of Organisms Live in Aquatic Life Zones?Aquatic Life Zones?

Aquatic systems contain floating, drifting, Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer swimming, bottom-dwelling, and decomposer organisms.organisms. Plankton: important group of weakly swimming, Plankton: important group of weakly swimming,

free-floating biota.free-floating biota.• Phytoplankton (plant), Zooplankton (animal), Phytoplankton (plant), Zooplankton (animal),

Ultraplankton (photosynthetic bacteria)Ultraplankton (photosynthetic bacteria) Nekton: fish, turtles, whales.Nekton: fish, turtles, whales. Benthos: bottom dwellers (barnacles, oysters).Benthos: bottom dwellers (barnacles, oysters). Decomposers: breakdown organic compounds Decomposers: breakdown organic compounds

(mostly bacteria).(mostly bacteria).

Life in LayersLife in Layers

Life in most aquatic systems is found in Life in most aquatic systems is found in surface, middle, and bottom layers.surface, middle, and bottom layers.

Temperature, access to sunlight for Temperature, access to sunlight for photosynthesis, dissolved oxygen content, photosynthesis, dissolved oxygen content, nutrient availability changes with depth.nutrient availability changes with depth. Euphotic zone (upper layer in deep water Euphotic zone (upper layer in deep water

habitats): sunlight can penetrate.habitats): sunlight can penetrate.

Marine EcosystemsMarine Ecosystems

Scientists estimate Scientists estimate that marine systems that marine systems provide $21 trillion in provide $21 trillion in goods and services goods and services per year – 70% more per year – 70% more than terrestrial than terrestrial ecosystems.ecosystems.


The Coastal Zone: The Coastal Zone: Where Most of the Action IsWhere Most of the Action Is

The coastal zone: the warm, nutrient-rich, The coastal zone: the warm, nutrient-rich, shallow water that extends from the high-tide shallow water that extends from the high-tide mark on land to the gently sloping, shallow mark on land to the gently sloping, shallow edge of the continental shelf.edge of the continental shelf.

The coastal zone makes up less than 10% of The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of the world’s ocean area but contains 90% of all marine species.all marine species. Provides numerous ecological and economic Provides numerous ecological and economic

services.services. Subject to human disturbance.Subject to human disturbance.

Fig. 6-5, p. 130

Dar

knes

sT

wil

igh

tP

ho

tosy

nth

esis

Sun

Continental shelf

Estuarine Zone

High tide

Low tide

Coastal Zone

Bathyal Zone

Euphotic Zone

Abyssal Zone

Sea level

Open Sea

Estuaries and Coastal WetlandsEstuaries and Coastal Wetlands Estuaries include river mouths, inlets, bays, Estuaries include river mouths, inlets, bays,

sounds, salt marshes in temperate zones and sounds, salt marshes in temperate zones and mangrove forests in tropical zonesmangrove forests in tropical zones

Highly productive ecosystemsHighly productive ecosystems Costal wetlands: land areas covered with water Costal wetlands: land areas covered with water

all or part of the yearall or part of the year River mouths, inlets, bays, sounds, salt marshes in River mouths, inlets, bays, sounds, salt marshes in

temperate zones, and mangrove forests in tropical temperate zones, and mangrove forests in tropical zoneszones

Fig. 6-6, p. 130

Fig. 6-7a, p. 131

All consumersand producers to decomposers

Secondary to higher-level consumer

Primary to secondary consumer

Producer to primary consumer

Soft-shelledclam

BacteriaClamworm

Zooplankton andsmall crustaceans

Smelt

MarshPeriwinkle

Phytoplankton

Herring gulls

SnowyEgret

Peregrine falcon

Cordgrass

Short-billedDowitcher

Fig. 6-7b, p. 131

Mangrove ForestsMangrove Forests Are found along about Are found along about

70% of gently sloping 70% of gently sloping sandy and silty sandy and silty coastlines in tropical coastlines in tropical and subtropical and subtropical regionsregions

Tropical equivalent of Tropical equivalent of salt marshessalt marshes

Worth $200K - $900K Worth $200K - $900K per square K, but per square K, but cleared for aquaculture cleared for aquaculture for about $20Kfor about $20K


Estuaries and Coastal Wetlands: Estuaries and Coastal Wetlands: Centers of ProductivityCenters of Productivity

Estuaries and coastal marshes provide Estuaries and coastal marshes provide ecological and economic services.ecological and economic services. Filter toxic pollutants, excess plant nutrients, Filter toxic pollutants, excess plant nutrients,

sediments, and other pollutants.sediments, and other pollutants. Reduce storm damage by absorbing waves Reduce storm damage by absorbing waves

and storing excess water produced by storms and storing excess water produced by storms and tsunamis.and tsunamis.

Provide food, habitats and nursery sites for Provide food, habitats and nursery sites for many aquatic species.many aquatic species.

Rocky and Sandy Shores: Rocky and Sandy Shores: Living with the TidesLiving with the Tides

Organisms experiencing daily low and high Organisms experiencing daily low and high tides have evolved a number of ways to tides have evolved a number of ways to survive under harsh and changing conditions.survive under harsh and changing conditions. Gravitational pull by moon and sun causes tides.Gravitational pull by moon and sun causes tides. Intertidal Zone: area of shoreline between low Intertidal Zone: area of shoreline between low

and high tides.and high tides.

Rocky and Sandy Shores: Rocky and Sandy Shores: Living with the TidesLiving with the Tides

Organisms in Organisms in intertidal zone intertidal zone develop specialized develop specialized niches to deal with niches to deal with daily changes in:daily changes in: TemperatureTemperature SalinitySalinity Wave actionWave action


Fig. 6-9, p. 132

Rocky Shore BeachSea star Hermit crab Shore crab

AnemoneSea urchin

Sculpin

Nudibranch

Low tide

Monterey flatworm

Kelp Sea lettuce

Barnacles

Mussel

Periwinkle

High tide

Fig. 6-9, p. 132

Barrier Beach

Peanut worm

Beach flea

TigerBeetle

DwarfOlive

Clam

High tide

GhostShrimpMole

Shrimp

Sandpiper

Moon snail

Sand dollarWhite sand macoma

Blue crab

Low tideSilversides

Barrier IslandsBarrier Islands

Low, narrow, sandy islands that form offshore Low, narrow, sandy islands that form offshore from a coastline.from a coastline.

Primary and secondary dunes on gently Primary and secondary dunes on gently sloping sandy barrier beaches protect land sloping sandy barrier beaches protect land from erosion by the sea.from erosion by the sea.


Threats to Coral Threats to Coral ReefsReefs

Biologically diverse Biologically diverse and productive coral and productive coral reefs are being reefs are being stressed by human stressed by human activities.activities.

Coral reefs can only Coral reefs can only live between 18-30 live between 18-30 ooC – a change in C – a change in one degree could one degree could cause bleachingcause bleaching


Fig. 6-12, p. 135

Ocean warming

Soil erosion

Algae growth from fertilizer runoff

Mangrove destruction

Bleaching

Rising sea levels

Increased UV exposure

Damage from anchors

Damage from fishing and diving

Natural Capital Degradation

Coral Reefs

Biological Zones in the Open Sea:Biological Zones in the Open Sea:Light RulesLight Rules

Euphotic zoneEuphotic zone: brightly lit surface layer. : brightly lit surface layer. Nutrient levels low, dissolved ONutrient levels low, dissolved O22 high, high,

photosynthetic activity.photosynthetic activity. Bathyal zoneBathyal zone: dimly lit middle layer.: dimly lit middle layer.

No photosynthetic activity, zooplankton and fish No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at live there and migrate to euphotic zone to feed at night.night.

Abyssal zoneAbyssal zone: dark bottom layer. : dark bottom layer. Very cold, little dissolved OVery cold, little dissolved O22..

Effects of Human Activities on Marine Effects of Human Activities on Marine Systems: Red AlertSystems: Red Alert

Human activities Human activities are destroying or are destroying or degrading many degrading many ecological and ecological and economic services economic services provided by the provided by the world’s coastal world’s coastal areas.areas.


FRESHWATER LIFE ZONESFRESHWATER LIFE ZONES

Freshwater life zones Freshwater life zones include:include: Standing (lentic) Standing (lentic)

waterwater such as lakes, such as lakes, ponds, and inland ponds, and inland wetlands.wetlands.

Flowing (lotic) Flowing (lotic) systemssystems such as such as streams and rivers. streams and rivers.


Lakes: Water-Filled DepressionsLakes: Water-Filled Depressions

Lakes are large natural bodies of standing Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, freshwater formed from precipitation, runoff, and groundwater seepage consisting of:and groundwater seepage consisting of: Littoral zoneLittoral zone (near shore, shallow, with rooted (near shore, shallow, with rooted

plants).plants). Limnetic zoneLimnetic zone (open, offshore area, sunlit). (open, offshore area, sunlit). Profundal zoneProfundal zone (deep, open water, too dark for (deep, open water, too dark for

photosynthesis).photosynthesis). Benthic zoneBenthic zone (bottom of lake, nourished by dead (bottom of lake, nourished by dead

matter).matter).

Lakes: Water-Filled DepressionsLakes: Water-Filled Depressions

During summer and winter in deep temperate During summer and winter in deep temperate zone lakes become stratified into zone lakes become stratified into temperature layers and will overturn.temperature layers and will overturn. This equalizes the temperature at all depths.This equalizes the temperature at all depths. Oxygen is brought from the surface to the lake Oxygen is brought from the surface to the lake

bottom and nutrients from the bottom are brought bottom and nutrients from the bottom are brought to the top.to the top.

What causes this overturning?What causes this overturning?

Fig. 6-15, p. 137

Pond snail

Benthic zone

Profundal zone

Limnetic zone

Sunlight

Blue-winged teal

Muskrat

Plankton

BloodwormsNorthern

pikeYellow perch

Diving beetle

Littoral zone

Painted turtle

Green frog

Effects of Plant Nutrients on Lakes:Effects of Plant Nutrients on Lakes:Too Much of a Good ThingToo Much of a Good Thing

Plant nutrients from a lake’s environment Plant nutrients from a lake’s environment affect the types and numbers of organisms it affect the types and numbers of organisms it can support.can support.



Plant nutrients from a lake’s environment Plant nutrients from a lake’s environment affect the types and numbers of organisms it affect the types and numbers of organisms it can support.can support. OligotrophicOligotrophic (poorly nourished) lake: Usually (poorly nourished) lake: Usually

newly formed lake with small supply of plant newly formed lake with small supply of plant nutrient input.nutrient input.

EutrophicEutrophic (well nourished) lake: Over time, (well nourished) lake: Over time, sediment, organic material, and inorganic sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant nutrients wash into lakes causing excessive plant growth.growth.

MesotrophicMesotrophic in-between. in-between.


Cultural eutrophicationCultural eutrophication:: Human inputs of nutrients from the atmosphere Human inputs of nutrients from the atmosphere

and urban and agricultural areas can accelerate and urban and agricultural areas can accelerate the eutrophication process.the eutrophication process.

Freshwater Streams and Rivers:Freshwater Streams and Rivers:From the Mountains to the OceansFrom the Mountains to the Oceans

Water flowing from mountains to the sea Water flowing from mountains to the sea creates different aquatic conditions and creates different aquatic conditions and habitats.habitats.


Case Study:Case Study:Dams, Wetlands, Hurricanes, Dams, Wetlands, Hurricanes,

and New Orleansand New Orleans Dams and levees have been built to control Dams and levees have been built to control

water flows in New Orleans.water flows in New Orleans. Reduction in natural flow has destroyed Reduction in natural flow has destroyed

natural wetlands.natural wetlands. Causes city to lie below sea-level (up to 3 Causes city to lie below sea-level (up to 3

meters).meters). Global sea levels have risen almost 0.3 meters Global sea levels have risen almost 0.3 meters

since 1900.since 1900.

Freshwater Inland Wetlands: Freshwater Inland Wetlands: Vital SpongesVital Sponges

Inland wetlands Inland wetlands act like natural act like natural sponges that sponges that absorb and store absorb and store excess water excess water from storms and from storms and provide a variety provide a variety of wildlife of wildlife habitats.habitats.


Freshwater Inland Wetlands: Freshwater Inland Wetlands: Vital SpongesVital Sponges

Filter and degrade pollutants.Filter and degrade pollutants. Reduce flooding and erosion by absorbing Reduce flooding and erosion by absorbing

slowly releasing overflows.slowly releasing overflows. Help replenish stream flows during dry Help replenish stream flows during dry

periods.periods. Help recharge ground aquifers.Help recharge ground aquifers. Provide economic resources and recreation.Provide economic resources and recreation.

Impacts of Human Activities on Impacts of Human Activities on Freshwater SystemsFreshwater Systems

Dams, cities, farmlands, and filled-in wetlands alter Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats.and degrade freshwater habitats. Dams, diversions and canals have fragmented about 40% Dams, diversions and canals have fragmented about 40%

of the world’s 237 large rivers.of the world’s 237 large rivers. Flood control levees and dikes alter and destroy aquatic Flood control levees and dikes alter and destroy aquatic

habitats.habitats. Cities and farmlands add pollutants and excess plant Cities and farmlands add pollutants and excess plant

nutrients to streams and rivers.nutrients to streams and rivers. Many inland wetlands have been drained or filled for Many inland wetlands have been drained or filled for

agriculture or (sub)urban development.agriculture or (sub)urban development.

Impacts of Human Activities on Impacts of Human Activities on Freshwater SystemsFreshwater Systems

These wetlands These wetlands have been ditched have been ditched and drained for and drained for cropland cropland conversion.conversion.


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Chapter 6 Aquatic Biodiversity. Chapter Overview Questions What are the basic types of aquatic life zones and what factors influence the kinds of life