Transcript Rocky Intertidal Zone

Rocky Intertidal Zone
General Characteristics
 Steep
coasts without large amounts
of sediment
 West
coast of US
– Active margin
– Uplift
 Northeast
Coast of US & Canada
– Ice sheets scraped sediment from the
shelf
Conditions
 Plenty
of food
– Shallow water = lots of light
– Nutrients
 Detritus
– Brought in by waves & tides
– Most important food source in many
communities
Organisms in Rocky Intertidal
 Mainly
epifauna
 Adaptations
for attachment:
– Byssal threads
– Holdfasts
– Tube feet
– Cement
Barnacles
Periwinkles
Sea Star
Sea Anemones
Lobsters
Sea Urchin
Mussels
Palm Seaweed
Rocky Coast Communities
 West
coast of US has more mature
communities
– Less seasonal changes
– Main limiting factor is predation
 East
coast is less mature
– Seasonal population changes
– Main limiting factor is climate
Competition for Space
 Sessile
attach
 Space
 Ways
organisms need place to
is limited
to outcompete other species
– Large # larva
– Loosen competition from rock
– Grow over competitors
Ecological Succession
Vertical Zonation
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In rocky intertidal, species not found
throughout; rather in a particular range
Distinct bands of organisms at
characteristic height in intertidal
Upper limit usu. determined by physical
factors
Lower limit determined by biological
factors – predation, competition
Keystone Predator
STARFISH FEEDING ON MUSSEL BED