The Intertidal Zone Sources used in the creation of this PowerPoint include: Fish 351 class website <http://courses.washington.edu/mb351/> Online PowerPoint Presentation <daphne.palomar.edu/panderson/PowerPoint/Chapter15> Google Images Nybakken,J.W. (2001). Marine biology: an ecological approach: fifth edition. Benjamin Cummings, San Francisco. Castro, P. & Huber, M. (2000). Marine biology: third edition. McGraw- Hill, Boston. Sverdrup,K.A., Duxbury, A.C., & Duxbury, A.B. (2005). An introduction to the world’s oceans: eighth edition. McGraw-Hill, Boston.

What is the Intertidal Zone? Area of the shore between high tide and low tide 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 Image from google images

Pacific Northwest Rocky Intertidal Zones Image from google images

Areas where tidal ranges are high, intertidal zones can reach depths of about 10 meters (33 feet)

A Dynamic Environment with challenges Temperature fluctuations Light Moisture/Desiccation Wave Shock/Energy Dissolved Oxygen Food Supply Images from google images

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 Slide Modified from: daphne.palomar.edu/panderson/PowerPoint/Chapter15

Rocky shores: Intertidal zonation and organisms Slide Source: daphne.palomar.edu/panderson/PowerPoint/Chapter15

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 Images from google images and Brian Moore

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 (or Supralittoral Zone) Above high-tide level Seldom submerged High air exposure The greatest challenges are drying out and thermal stress Image from Rick Keil

Splash Zone Limpets (aquatic snail) Periwinkles dominate (sea snails) Limpets (aquatic snail) Lichens (a symbiotic association between a fungus and an alga) Encrusting algae Shore crabs Periwinkle photo by Terry Klinger - University of Washington; other photos from google images Lichens soak up water like a sponge and store it to avoid desiccation. Algae in these zones are resistant to drying out. Periwinkles can breathe air, tolerate extreme temperature, and go months without water. Limpets can trap moisture under their shells. Then can also raise their shells off of the rock for temperature regulation. Shore crabs scavenge dead carcasses and scrape algae off rocks.

Pickleweed a.k.a Sea Asparagus a.k.a. Salicornia - is a genus of succulent, halophyte flowering plants in the family Amaranthaceae that grow in salt marshes, on beaches, and among mangroves. http://www.elkhornslough.org

Upper Intertidal Zone Submerged regularly (once or twice a day) Affected by desiccation (the state of extreme dryness), competition, & predation Image from google images

Upper Intertidal Zone Barnacles dominate The barnacle is a hardy animal that is found in or very closely to sea water. Although it is frequently confused for a mollusc because of its hard outer shell, it is actually a crustacean, closely related to crabs and lobsters. Barnacles are most often seen as roughly circular sessile invertebrates (which means that they cannot move on their own), and are permanently attached to the substrate they live on. In their juvenile form they are free-floating, but eventually they attach themselves to any nearby rock, shell, or other object and stay there for the rest of their lives. Their shells are composed of calcite. Gooseneck barnacles -acorn barnacles are also abundant; often larger barnacles are closer to the water, smaller species are found higher up *keys to success - larval settlement pattern (upper-small;lower-large), desiccation tolerance, competition, predation (whelks) 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 Image from Rick Keil

Middle Intertidal Zone Mussels Barnacles Seaweeds Image from Brian Moore

Keystone Species: Pisaster ! Pisaster ochraceus, generally known as the purple sea star, ochre sea star or ochre starfish, is a common starfish found among the waters of the Pacific Ocean. Voracious predators How do seastars ingest their prey? Sea stars use suction in the tube feet for movement and feeding. They wrap their bodies around quahogs and other bivalves, using the suction from their tube feet to pull shells apart. When the prey is opened, the sea star pushes its stomach out of its body and into the bivalve, secreting enzymes that digest the prey's soft body tissues. The liquefied bivalve is then absorbed into the stomach. Sea stars feed often, and their size depends on the amount of food they eat, not on their age. Often found in middle/lower intertidal (prone to drying out) Image from Brian Moore Sea stars ingest prey by inserting their stomachs into their prey’s shell and digesting the prey inside it’s own shell. Bob Payne - Pisaster removal experiment --> w/ no sea stars, mussels take over and diversity in the middle intertidal decreases to nonexistent

Lower Intertidal Zone Submerged most of the time Good place for predators and seaweeds Compete for light & space Image from google images

Lower Intertidal Zone Seaweed Surfgrass Anemones Seastars Images from Brian Moore and Rick Keil

Photic Zone Green Algae Brown Algae Red 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.) http://lh4.ggpht.com http://plantphys.info

Lower Intertidal Zone Algae dominates this zone. Marine algae, or seaweeds, can be found in patches among barnacles and mussels of the mid-intertidal zone and in some areas the brown algae can extend as far up as the black zone eliminating all other zones. In general though, they begin to form a distinct band below the barnacles. Zonation patterns of algae are governed by exposure to the tide and wave impact, as well as by species interactions such as grazing by invertebrates, and competition for space and light.

Which zone? How can you tell? Pictures by Brian Moore and Rick Keil Upper left - upper intertidal - barnacles (acorn and gooseneck); Upper right:Splash Zone - periwinkles!; Bottom - lower intertidal - seaweeds

What determines the limits of these species’ intertidal ranges? Images from google images and Rick Keil

What would happen if you removed the seastars from this tidepool? Image from google images Seastar removal - mussels extend lower into intertidal - take over and diversity decreases