Tidal Environments
I. Affects of Turbulence
A. Turbulence - wave action
B. Keeps inshore waters from
stratifying (layering)
C. Causes substrate
particles
(sand) to
remain
suspended.
II. Substrate
A. Definition - material an
organism lives in or on,
including sand and rocks.
III. Tidal Zonation
A. Low-Tide Conditions
1. Epifauna – organisms living on substrate surface
(intertidal zone organisms)
2. High stress for sessile organisms due to
exposure of the elements.
A. Desiccation – drying out
B. Predation
C. Temperature & Salinity changes
3. Survival Method
A. Motile Organisms-Run & hide
B. Sessile organisms-Clam up
method
B. High Tide Conditions
1. Once Exposed Now Submerged
2. Force of crashing-in waves
3. Wave Intensity varies due to the
bending of the waves
IV. Causes of Zonation
A. Physical factors:
Alternation between submersion and
exposure to air
B. Biological factors:
1. competition and predation
2. grazing-affects algal distribution
3. offspring reproduction-variable
due to water conditions/weather
and adult reproduction
V. Types of Tidal Zones
• Sandy Beach
• Rocky Shore
A. Sandy Beach
1. Composed of loose sediment
that’s easily shifted by wind and
waves.
2. Zones easily recognized
3. Sandy beaches are the most
familiar of tidal zones.
B. ROCKY SHORE
1. Occur on steep coasts
(West Coast of America).
2. Formed from uplifts on
tectonic plates or rising
coasts from melting ice.
3. Lacking large amounts of
sediment.
4. Rocky Shore Zones
Supralittoral zone
Littoral zone
Infralittoral zone
5. Upper intertidal (Supralittoral zone)
a. Conditions as terrestrial as
they are marine
b. Infrequent wetting by high tides
and waves
c. Sparsely inhabited by marine
organisms
6. Middle Intertidal (littoral zone)
a. Frequently submerged by
tides and waves;
b. Abundance of plant nutrients,
oxygen, and planktonic food
c. Barnacle and
Mussel habitation
7. Lower intertidal (Infralittoral zone)
a. Submerged most of the time
b. Organisms tolerate only brief
exposure to air
c. Numerous seaweed species; algae –
more red and brown than green
d. Animals: anemones, snails, sea
spiders, hydroids,
sea stars,
sea urchins,
brittle stars, and
sea cucumbers
.