1. The Intertidal Zone
Chapter 13

2. I. Characteristics of the Intertidal Zone
A. Alternately exposed and submerged by tides.
B. Must tolerate radical changes in temperature, salinity, and moisture and waves.

3. II. Rocky Shores
A. Rocky shores are inhabited by many organisms that tend to form bands, or zones, on the rocks.

4. B. In addition to physical factors, biotic factors such as grazing, predation, and competition all determine the distribution of organisms on the rocky shore.

5. C. Rocky Shore Zonation (Tropical)
1. Supralittoral Fringe (Splash Zone)
a. White Zone: very dry / white knobby periwinkle
b. Gray Zone: sea spray / gray nerite snails
c. Black Zone: high spring tide / black fuzzy chiton

6. 2. Midlittoral Zone (Alternately Exposed and Submerged)
a. Tide pools are found in this zone.
b. Yellow Zone: yellow and green algae
c. Pink Zone: pink coralline algae

7. 3. Subtidal Zone (Lowest of Low Tides)
a. usually more stable
b. supports a greater diversity of organisms

8. D. Ecology of the Rocky Shore: Top-Down and Bottom-Up Factors
1. Top-Down a. Effects flow down the food chain. b. Competition, herbivory and predation.

9. 2. Bottom-Up
a. Affect the bottom of the food chain and therefore the whole food chain.
b. Limiting nutrients and recruitment (reproduction and immigration).

10. III. Sandy Shores A. Distribution influenced by wave action.
B. Sandy shores can be divided into zones on the basis of the amount of tidal coverage they receive.

11. 1. Supralittoral Zone: characterized by sand
dunes and infauna (burrowers).

12. 2. Mid-littoral Zone
a. Organisms that live in this
region are predominantly
burrowers.
Low tide  remain hidden in their burrows
High tide  emerge and
forage for food
b. Vertical Zonation
(1) Based on moisture in the sand (retention, resurgence and saturation)
(2) Reference Figure 13-16

13. March is Seagrass Awareness Month!
3. Subtidal Zone
a. Exposed only during spring tides and is truly a marine environment.
b. Where the bottom is bare sand, burrowing organisms predominate.
c. In other areas where the bottom is covered with seagrass, rocks, or coral rubble, a greater diversity of organisms can be found.
March is Seagrass Awareness Month!