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

A Dynamic 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

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… 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. 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.

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

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 Species: 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) Red Algae –Absorb short blue-green light –Ex. Encrusting coralline algae (Lithothamnion spp.)

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, PM - $25