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http://bellaonthebeach.files.wordpress.com/2009/01/water.jpg

BIOL 3240 Plant and Animal Ecology – Water

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Water Availability

• The tendency of water to …

determine whether an organism tends to lose or gain water from its environment.

– ____________ important factor!

BIOL 3240 Plant and Animal Ecology – Water

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Water Content of Air• ___________ accounts for much of water lost

by terrestrial organisms.– As water vapor in the air increases, the water

concentration gradient from organisms to air is __________, thus evaporative loss is decreased.

– Would you buy a “swamp cooler” to help you keep cool in the cypress swamps of southern U.S.?

BIOL 3240 Plant and Animal Ecology – Water

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Water Content of Air• Relative Humidity:

• ________________ is measured as the water vapor per unit volume of air.

• _____________________________ is measured as the quantity of water vapor air can potentially hold.

–

BIOL 3240 Plant and Animal Ecology – Water

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Water Content of Air• Total Atmospheric Pressure

– • Water Vapor Pressure

– • Saturation Water Vapor Pressure

– • Vapor Pressure Deficit

–

BIOL 3240 Plant and Animal Ecology – Water

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Evaporative Water LossBIOL 3240 Plant and Animal Ecology – Water

A high vpd indicates that the H2O vapor content of air is…

Where the vpd is high, the rate of evaporative

H2O loss by organisms is…

A low vpd indicates that the H2O vapor content of air is…

Where the vpd is low, the rate of evaporative

H2O loss by organisms is…

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Water Movement in Aquatic Environments

• Water moves down concentration gradient.– Water is more concentrated in …

• Aquatic organisms can be viewed as an ______________ bounded by a _______ _______________ floating in an another ______________________.

BIOL 3240 Plant and Animal Ecology – Water

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Water Movement in Aquatic Environments

• If two environments differ in water or salt concentrations, substances will tend to move…

– Diffusion• Osmosis:

BIOL 3240 Plant and Animal Ecology – Water

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Water Movement in Aquatic Environment

• ____________: Body fluids and external fluid are at the same concentration.

• ____________: Body fluids are at a higher concentration than the external environment.

• ____________: Body fluids are at a lower concentration than the external environment.

BIOL 3240 Plant and Animal Ecology – Water

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BIOL 3240 Plant and Animal Ecology – Water

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BIOL 3240 Plant and Animal Ecology – Water

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BIOL 3240 Plant and Animal Ecology – Water

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Water and Salt Balance in Aquatic Environments

• Freshwater Fish and Invertebrates– Hyperosmotic organisms that …

• Replace ________ by absorbing sodium and chloride at base of gill filaments and by ingesting food.

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Osmoregulation by Freshwater Organisms

BIOL 3240 Plant and Animal Ecology – Water

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Osmoregulation by Marine Organisms

BIOL 3240 Plant and Animal Ecology – Water

What happens with H2O in hypoosmotic

bony fish?

What happens with salts in hypoosmotic

bony fish?

How do hypoosmotic

bony fish compensate? How do hypoosmotic bony

fish compensate?

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Water and Salt Balance in Aquatic Environments

• Marine Fish and Invertebrates– __________ organisms do not have to expend

energy overcoming osmotic gradient.• Sharks, skates, rays -

– Slowly gain water osmotically.• Marine bony fish are strongly hypoosmotic, thus need to…

BIOL 3240 Plant and Animal Ecology – Water

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Water Movement Between Soils and Plants

• Water moving between soil and plants flows...

• ______________ (Ψ) is the capacity to perform work.– Dependent on free energy content.– Pure Water ψ = .

• Ψ in nature generally ____________.• Ψsolute measures the reduction in Ψ due to…

BIOL 3240 Plant and Animal Ecology – Water

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BIOL 3240 Plant and Animal Ecology – Water?

?

?

?

?

?

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Water Movement Between Soils and Plants

– Ψplant = Ψsolute + Ψmatrix + Ψpressure

– ______________: Water’s tendency to adhere to container walls.

– Ψpressure is the reduction in water potential due to negative pressure created by…

– As long as Ψplant < Ψsoil, water flows from…

BIOL 3240 Plant and Animal Ecology – Water

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Water Regulation on Land

• Terrestrial organisms face (2) major challenges:–

–

BIOL 3240 Plant and Animal Ecology – Water

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Water Regulation on Land - Animals

BIOL 3240 Plant and Animal Ecology – Water

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Water Regulation on Land - Animals

• Wia= Wd + Wf + Wa - We - Ws

• Wia= • Wd = • Wf = • Wa = • We = • Ws =

BIOL 3240 Plant and Animal Ecology – Water

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Water Acquisition by Animals

• Most terrestrial animals satisfy their water needs via…– Can also be gained via ______________ through

oxidation of glucose:

•

– ________________________ refers to the water released during cellular respiration.

BIOL 3240 Plant and Animal Ecology – Water

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Water Regulation on Land - PlantsBIOL 3240 Plant and Animal Ecology – Water

Water is lost via what

mechanism(s)?

Water is lost via what

mechanism(s)?

How might Water be gained?

Water is lost via what mechanism(s)

due to wind?

How might Water be gained?

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Water Regulation on Land - Plants• Wip= Wr + Wa - Wt - Ws

• Wip=

• Wr =

• Wa =

• Wt =

• Ws =

BIOL 3240 Plant and Animal Ecology – Water

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Water Acquisition by Plants

• Extent of plant root development often reflects differences in water availability.– Deeper roots often help plants…

• Park found supportive evidence via studies conducted on common Japanese grasses, Digitaria adscendens and Eleusine indica.

BIOL 3240 Plant and Animal Ecology – Water

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Water Conservation by Plants and Animals

• Many terrestrial organisms equipped with _______________________.

• Concentrated _______________.• __________________________ in breath.• __________________________ to avoid stress

times.• ___________________ in response to drought.• • •

BIOL 3240 Plant and Animal Ecology – Water

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BIOL 3240 Plant and Animal Ecology – WaterHow is heat

gain reduced?

How is heat gain

reduced?

How is heat gain

reduced?

How is H2O loss

decreased?

How is H2O loss decreased?

How is heat gain

reduced?

How is heat gain

reduced?

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Dissimilar Organisms with Similar Approaches to Desert Life

• Camels– Can withstand water loss up to ___%.

• •

• Saguaro Cactus– Trunk / arms act as ...– Dense network of shallow roots. WHY?–

BIOL 3240 Plant and Animal Ecology – Water

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Two Arthropods with Opposite Approaches to Desert Life

• Scorpions– – –

BIOL 3240 Plant and Animal Ecology – Water

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• Cicadas (Diceroprocta apache) – – – How?

http://www.learnnowonline.net/nucpan/wp-content/uploads/2007/08/cicada2.JPG

http://www.canyouseethesunset.com/uploaded_images/cicada-2.jpg

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BIOL 3240 Plant and Animal Ecology – Water