Download Intertidal Zonation: The Rocky Intertidal

Intertidal Glory
Christen Foehring
11/12/09
 Area of the shore between mean high water and mean
low water
 Also known as the littoral zone
What is intertidal zonation?
• Banding of organisms in
the intertidal zone
• Zones are not absolute
• Sorted out by ability to
cope with stresses
• Also called vertical
zonation
Pacific Northwest Rocky
Intertidal Zones
An Ever-Changing Environment
•
•
•
•
•
•
Temperature
Light
Moisture/Desiccation
Wave Shock/Energy
Dissolved Oxygen
Food Supply
Rocky shores
• Zonation of rocky shores:
–
–
–
–
Splash/ Spray zone (rarely covered by water)
Upper intertidal zone
Middle intertidal zone
Lower intertidal zone (rarely exposed)
• Upper zones have mostly shelled organisms
• Lower zones have many soft-bodied
organisms and algae
• Why?
Rocky shores: Intertidal
zonation and organisms
Different Stresses for Different
Zones
•
•
•
•
Upper Zones
Exposure (air &
weather)
Heat
Predation by birds
and land animals
Wave turbulence
Lower Zones
• Competition (food &
space)
• Predation by aquatic
animals
General Rule of Thumb…
• An organism’s upper limit
is determined by physical
factors (i.e.desiccation,
temperature).
• The higher an organism
lives, the more capable it
must be of tolerating
exposure to air and sun.
• Its lower limit is determined by
biological factors (i.e.
predation, competition)
• The lower an organism goes,
the more capable it must be of
withstanding competition
pressures for space and
resources and avoiding
predation.
Splash Zone
• Above high-tide level
• Seldom submerged
• High air exposure
Splash Zone
• Periwinkles
dominate
• Limpets
• Lichens
• Encrusting algae
• Shore crabs
Pickleweed
a.k.a
Sea Asparagus
http://www.elkhornslough.org
http://2.bp.blogspot.com
Upper Intertidal Zone
• Submerged regularly
(once or twice a day)
• Affected by desiccation,
competition, & predation
Upper Intertidal Zone
Barnacles dominate
Photo Credit: Trina (Fish 351)
Middle Intertidal Zone
• Lower limit of
barnacles is set by
competition with
mussels in this zone
• Mussels are more
prone to drying out
than barnacles
• Lower limit of mussels
is set by seastars
Middle Intertidal Zone
• Mussels
• Barnacles
• Seaweeds
Keystone Predator:
Pisaster !
• Voracious predators
• How do seastars ingest
their prey?
• Often found in
middle/lower intertidal
(prone to drying out)
• What happens when
humans remove the
seastars?
Lower Intertidal Zone
• Submerged most of
the time
• Good place for
predators and
seaweeds
• Compete for light &
space
Lower Intertidal Zone
•
•
•
•
Seaweed
Surfgrass
Anemones
Seastars
• Green Algae
– Absorb short & long
wavelengths
– Ex. Sea lettuce (Ulva spp.)
• Brown Algae
– Capable of absorbing shorter
wavelengths
– Ex. Rockweed (Fucus
gardneri)
http://lh4.ggpht.com
• Red Algae
– Absorb short blue-green light
– Ex. Encrusting coralline algae
(Lithothamnion spp.)
http://plantphys.info
Which zone? How can you tell?
What determines the limits of
these species’ intertidal ranges?
What would happen if you
removed the seastars from this
tidepool?
• Mini Quadrats
• Piling Zonation aka
“personal piling”
– Intertidal Zonation
– Compare/Contrast Species
– Art
• Perspective writing
(intertidal organism)
• Periwinkle Observation
Activity
• Common PNW marine intertidal organisms
– Answers to the questions kids ask most often
(what is it, what does it eat, who eats it, can I
eat it, where does it live, is it like a ___?)
• Tidepool Explorations - boots & flashlights
required!
Come see her at Benaroya Hall
Wednesday, November 18,2009
7 PM - $25
http://www.sundancechannel.com/greenporno