lecture 7 rocky intertidal. relative tide levels
TRANSCRIPT
Lecture 7 ROCKY INTERTIDAL
RELATIVE TIDE LEVELS
RELATIVE TIDE LEVELS
-EFFECT OF SLOPE
MHWS
MHWN
MTL
MLWN
MLWS
ZONES CAN BE SEVERAL TENS OF METRESWIDE
ZONES CAN BE LESS THANA METRE WIDE
RELATIVE TIDE LEVELS
-EFFECT OF SLOPE
Slope and Substrate
SSlope
Substrate Size Wave Action
If you know any two factors, you can determine the third.
Slope and Substrate
Steep slope
Strong wave action
Coarse substrate
Water drains at low tide
Gradual slope
Weak wave actionFine substrate
Water retained at low tide
Slope and Substrate
Decreasing sediment size
Slope and Substrate
High wave/ steep slope
Slope and Substrate
Low wave/ gentle slope
Stephenson and Stephenson Classification of Rocky Intertidal Shores
EHWS
ELWSInfralittoral
Upper limit - Laminaria
Mytilus
Ascophyllum
Barnacles
Upper limit - Barnacles
Upper limit - Littorina
Infralittoral fringe
Midlittoral
Supralittoral fringe
Supralittoral
After Stephenson & Stephenson (1949)
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
Semibalanusbalanoides-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
Acmaea-limpet
Littorina littorea-periwinkle
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
Strongylocentrotusdroebachiensis
Ulva
Stephenson and Stephenson Classification of Rocky Intertidal Shores
d. Infralittoral
Asterias vulgaris
Critical Tide Levels
(Doty, 1946. Ecology 27: 315-328 )
Length of maximum submergence
Tide level
Critical tide levels
(Doty, 1946. Ecology 27: 315-328 )
Doty – Algal distributions
Druehl & Green, 1982. Mar.Ecol. Prog Ser. 9: 163
More realistic data on submergence
Druehl & Green, 1982. Mar.Ecol. Prog Ser. 9: 163
Next time
Intertidal Zonation – Physical Factors