ROCKY INTERTIDAL

RELATIVE TIDE LEVELS

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

RELATIVE TIDE LEVELS -EFFECT OF SLOPE

Slope and Substrate SSlope Substrate Size Wave Action

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

Slope and Substrate

Stephenson and Stephenson Classification of Rocky Intertidal Shores

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

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

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

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

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

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

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

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

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

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

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

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

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

Critical Tide Levels (Doty, 1946)