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Chapter 5

AQUATIC

BIOMES

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OUTLINE

• Marine Ecosystems

Coasts

- Sandy, Rocky, Salt Marsh, Mangrove

Coral Reefs

Open Ocean

Hydrothermal Vents

• Freshwater Ecosystems

- Lakes, Rivers, Wetlands

• Human Disturbance

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MARINE ECOSYSTEMS

• Oceans cover 3/4 of Earth’s surface.

• Photosynthesis is carried out by algae or free

floating plants (phytoplankton). Greatest

amount of photosynthesis near the coast where

nutrients wash in.

• Organisms die and fall to sea floor where the

nutrients are used in deep ocean ecosystems.

• Upwelling currents circulate nutrients from the

ocean floor back to the surface.

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MARINE ECOSYSTEMS

• VERTICAL STRATIFICATION is a key feature.

Light and temperature decrease with depth and deep ocean species often grow slowly.

Cold water holds more oxygen than warm water so productivity is often high in cold oceans such as the North Atlantic.

• Ocean systems classified:

LITTORAL – near/on shore

PELAGIC - water column above the bottom

BENTHIC - bottom

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MARINE ORGANISMS• Aquatic organisms are classified based on how

they move:

PLANKTON – Float and are carried by ocean currents

- Phytoplankton – plants (algae, diatoms)

- Zooplankton – animals (eggs, larvae, jellies)

NEKTON – are able to swim (fish, whales, turtles, etc)

NEUSTON – organisms floating/moving on the surface of the water (man-of-war, water striders)

BENTHOS - live on or in the bottom –dig/crawl (clams, worms, sea stars, etc)

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ZONES OF THE OCEAN

• LITTORAL ZONE

Coastline or shore is

called the. It is

affected by tides.

• NERITIC ZONE away

from shore, where

light can penetrate

bottom (shallow)

• PELAGIC ZONE is

away from the coast

and unaffected by

tides.

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TIDAL ZONES• SUPRATIDAL – above high tide

• INTERTIDAL – between high and low tide

• SUBTIDAL – under the low tide

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SANDY BEACHES / BARRIER ISLANDS

• Narrow islands made of sand that form parallel

to a coastline

• Provide protection from storms, waves, tides

• Since they are made of sand, they should not

be built on, but they are. Oftentimes, storms

destroy the buildings.

examples:

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ROCKY SHORE• Intertidal zone where organisms have

adaptations to withstand exposure to air and

can “stick” to the rocks against wave and

current action. Exhibit vertical zonation.

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TIDE POOLS

• Depressions in a rocky shoreline that are

flooded at high tide but retain some water at

low tide

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ESTUARINE ENVIRONMENTS

• ESTUARY – A bay or semi-enclosed body of

water that forms where rivers and ocean waters

mix.

• Form BRACKISH WATER - diluted salt water

• Estuaries have high productivity and are

protected areas used by many marine organisms

as nurseries and feeding grounds.

ie: salt marsh & mangroves

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SALT MARSH

• SALT MARSHES - coastal wetlands flooded by

tidal waters

• TEMPERATE ESTUARY

• Nutrient rich & biologically diverse.

• 2/3 of marine fish and shellfish rely on estuaries

for spawning and development.

• Threatened by sewage

& agricultural pollutants

from coastal cities

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MANGROVES

• Mangroves are trees that grow in saltwater

along tropical coastlines.

• a TROPICAL ESTUARY

• Help stabilize shoreline – roots prevent erosion

• Nurseries for coral reef organisms

• Mangroves are cut for timber & aquaculture

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CORAL REEFS• Corals are aggregations of coral colonies Their

calcium rich skeletons build up the reef.

Corals have a mutualistic relationship with algae that produce food for the coral animals. Light must penetrate for algal photosynthesis. Therefore, corals live within the photic zone.

Threatened by trash, sewage, urban runoff, industrial waste, introduced pathogens and global warming.

One third of coral reefs have already been destroyed and 60% of the remaining reefs will probably be dead by 2030 ( 2006 UNESCO Conference).

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Global warming causes CORAL BLEACHING in which corals expel their algal partners and then die.

OCEAN ACIDIFICATIONReduces corals ability to create their calcium exoskeletons

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ZONES OF THE OPEN OCEAN

• EPIPELAGIC ZONE

or EUPHOTIC ZONE

or PHOTIC ZONE

• Where enough light

can penetrate – up

to 600 feet – for

photosynthesis to

take place.

• Majority of

biodiversity is here.

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ZONES OF THE OPEN OCEAN

• MESOPELAGIC ZONE

• 200 meters to 1000m

• “Twilight Zone”

• Large predators such as

sharks and squid

• BATHYPELAGIC ZONE

• 1000 to 4000m

• Many organisms create light

– BIOLUMINESCENCE

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ZONES OF THE OPEN OCEAN

• ABYSSAL ZONE

• 4000 – 6000m

• Extreme HYDROSTATIC

PRESSURE

• Many benthic organisms feed

on detritus and dead

organisms that sank to the

bottom

• HADAL ZONE

• Trenches that extend to 11,000+ meters

• Mariana Trench – deepest place on earth.

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HYDROTHERMAL VENT COMMUNITY

This community contains

tube worms, mussels,

etc. supported by

microbes that capture

chemical energy from

thermal vents on the

ocean floor. These

organisms are adapted to

extreme temperatures

(7000 F) and intense

hydrostatic pressure.

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HYDROTHERMAL VENT COMMUNITY

Bacteria (archaea)

convert chemicals such

as hydrogen sulfide and

methane into glucose in a

process called

CHEMOSYNTHESIS.

Mutualistic organisms

such as clams, mussels,

shrimp and tube worms

house the archaea.

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HYDROTHERMAL VENT COMMUNITY

The intense heat dissolves metals and other

inorganic substances from the rock. These form

chimney-like structures called “Smokers” and

metal rich sediments.

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WETLANDS• Land surface is saturated or covered with water

at least part of the year.

SWAMPS - Wetlands with trees.

MARSHES - Wetlands without trees.

BOGS & FENS - Waterlogged soils that tend to accumulate peat. Generally, nutrient poor with low productivity, but many unusual species.

- BOGS are fed by precipitation

- FENS are fed from groundwater

• Water usually shallow enough to allow full sunlight penetration, so the majority of wetlands have high productivity.

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WETLANDS

• Conservation is very important due to rich biodiversity. Wetlands are the breeding grounds for birds and aquatic species. Make up less than 5% of land area, but contain 33% of endangered species. One of the greatest areas of concern for biologists.

• May gradually convert to terrestrial communities through succession

• Trap and filter water, and store runoff.

• About half of all original wetlands in the U.S. have been degraded over the past 250 years.

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Wetlands

Bog

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FRESHWATER ECOSYSTEMS

• LAKES

Freshwater lakes have distinct VERTICAL

ZONES or VERTICAL STRATIFICATION.

- EPILIMNION - warm upper layer

- HYPOLIMNION - cold, deeper layer that

does not mix

- BENTHOS – bottom

- LIMNETIC ZONE - area in water that

light penetrates

- PROFUNDAL ZONE - area in water

below light penetration

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LAYERS OF A LAKE

THERMOCLINE - distinctive temperature

transition zone that separates upper layer and

deeper layer. Layers “overturn” when seasons

change – in summer the top is warmer, in winter

the bottom is warmer – this mixes nutrients

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PLANTS OF A LAKE

EMERGENT PLANTS – rooted on bottom but

leaves and stems extend out of water.

SUBMERGED PLANTS – plants are completely

under water

EMERGENT PLANTS – rooted on bottom with

leaves and flowers on the surface

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ANIMALS OF A LAKE

FISH – stay near center and deep in winter to

avoid freezing.

INSECTS – generally live at the surface or in

detritus. Larvae feed on plants, adults usually fly

REPTILES/AMPHIBIANS – hibernate in mud

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PRODUCTIVITY OF A LAKE

OLIGOTROPHIC lakes

are those bodies of

water that have a

poor nutrient supply

and little/no plant life

MESOTROPHIC lakes

are in between...

EUTROPHIC lakes

have a good nutrient

supply and support

high plant growth.

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HUMAN DISTURBANCE

ACID RAIN – stay near center and deep in

winter to avoid freezing.

SEWAGE, THERMAL POLLUTION

RUNOFF – of fertilizers & detergents can cause

EUTROPHICATION.

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FLOWING WATER – RIVERS / STREAMS

SOURCE – rain,

meting ice, lakes.

FLOODPLAIN –

FERTILE low lying

areas surrounding a

river

DRAINAGE BASIN –

the total land area that

drains into the river

DELTA – collection of

sediments from the

river – generally fertile

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FLOWING WATER – RIVERS / STREAMS

RIPARIAN ZONE – contains water loving plants

and animals adapted to both water and land.

ie: reeds, sedges, cottonwood, willow,

ie: musk rats, otters, turtles, amphibians

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FLOWING WATER – RIVERS / STREAMS

MAJOR RIVER SYSTEMS – Large rivers have

drainage systems that incorporate wide

continental areas.

HUMAN DISTURBANCES include dams,

irrigation, hydroelectric facilities, runoff, and

industrial dumping