Chapter 6 Aquatic Biodiversity. Core Case Study: Why Should We Care About Coral Reefs? Coral reefs...

Chapter 6Chapter 6

Aquatic BiodiversityAquatic Biodiversity

Core Case Study:Core Case Study: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 waters of the tropics and tropics and subtropics.subtropics. Formed by Formed by

massive colonies massive colonies of polyps.of polyps.

Figure 6-1Figure 6-1

Fig. 6-1a, p. 126

Fig. 6-1b, p. 126

Core Case Study:Core Case Study: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 Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s cover almost three-fourths of the earth’s surfacesurface


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) Necton: fish, turtles, whales.Necton: 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).

SALTWATER LIFE ZONESSALTWATER LIFE ZONES

The oceans that The oceans that occupy most of the occupy most of the earth’s surface earth’s surface provide many provide many ecological and ecological and economic services.economic services.


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.

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.

The Coastal ZoneThe Coastal Zone


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..

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.


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

Estuaries include river Estuaries include river mouths, inlets, bays, mouths, inlets, bays, sounds, salt marshes sounds, salt marshes in temperate zones in temperate zones and mangrove forests and mangrove forests in tropical zones.in tropical zones.


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

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.

Mangrove ForestsMangrove Forests

Are found along Are found along about 70% of about 70% of gently sloping gently sloping sandy and silty sandy and silty coastlines in coastlines in tropical and tropical and subtropical subtropical regions.regions.


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

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.


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

Threats to Threats to Coral Reefs:Coral Reefs:Increasing Increasing StressesStresses

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


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

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).


During summer and winter in deep temperate During summer and winter in deep temperate zone lakes the become stratified into zone lakes the 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?

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.


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.


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.


Chapter 6 Aquatic Biodiversity. Core Case Study: Why Should We Care About Coral Reefs? Coral reefs...

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