1. ROCKY INTERTIDAL

2. RELATIVE TIDE LEVELS

3. RELATIVE TIDE LEVELS -EFFECT OF SLOPE MHWS MHWN MTL MLWN MLWS
ZONES CAN
BE LESS THAN
A METRE WIDE
MTL
ZONES CAN BE SEVERAL TENS OF METRES
WIDE
MLWN
MLWS

4. RELATIVE TIDE LEVELS
-EFFECT OF SLOPE

5. Slope and Substrate
SSlope
Substrate Size
Wave Action

6. Slope and Substrate Coarse substrate Strong wave action
Water drains at low tide
Strong wave action
Steep slope
Fine substrate
Water retained at low tide
Weak wave action
Gradual slope

7. Slope and Substrate

8. Stephenson and Stephenson Classification of Rocky Intertidal Shores

9. Stephenson and Stephenson Classification of Rocky Intertidal Shores
a. Supralittoral Zone
Xanthoria

10. Stephenson and Stephenson Classification of Rocky Intertidal Shores
b. Supralittoral Fringe
Calothrix
Verrucaria
Littorina

11. Stephenson and Stephenson Classification of Rocky Intertidal Shores
b. Supralittoral Fringe
Bottom of zone
Fucus spiralis
Semibalanus balanoides

12. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
- begins at upper limit of barnacles

13. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
4 dominant species
Semibalanus
balanoides
-northern rock barnacle
Ascophyllum
nodosum - knotted wrack

14. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
4 dominant species
Mytilus edulis
-blue mussel
Fucus vesiculosus
- bladder wrack

15. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
Other common species
Littorina littorea
-periwinkle
Acmaea
-limpet

16. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
Other common species
Thais
-whelk

17. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
On stalks of Ascophyllum
Sertularia
Flustrellidra
Polysiphonia

18. Stephenson and Stephenson Classification of Rocky Intertidal Shores
c. Midlittoral
Lower midlittoral
Porphyra
Palmaria

19. Stephenson and Stephenson Classification of Rocky Intertidal Shores
d. Infralittoral
Laminaria
- kelp

20. Stephenson and Stephenson Classification of Rocky Intertidal Shores
d. Infralittoral
Strongylocentrotus
droebachiensis
Ulva

21. Stephenson and Stephenson Classification of Rocky Intertidal Shores
d. Infralittoral
Asterias vulgaris

22. Critical Tide Levels
(Doty, 1946)