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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!
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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.?
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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.
–
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Water Content of Air• Total Atmospheric Pressure
– • Water Vapor Pressure
– • Saturation Water Vapor Pressure
– • Vapor Pressure Deficit
–
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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 ______________________.
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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:
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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.
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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
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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…
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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…
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BIOL 3240 Plant and Animal Ecology – Water?
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?
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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…
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Water Regulation on Land
• Terrestrial organisms face (2) major challenges:–
–
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Water Regulation on Land - Animals
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Water Regulation on Land - Animals
• Wia= Wd + Wf + Wa - We - Ws
• Wia= • Wd = • Wf = • Wa = • We = • Ws =
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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.
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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 =
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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.
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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.• • •
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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?–
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Two Arthropods with Opposite Approaches to Desert Life
• Scorpions– – –
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• Cicadas (Diceroprocta apache) – – – How?
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BIOL 3240 Plant and Animal Ecology – Water