Tidal Environments

A. Turbulence - wave action

B. Keeps inshore waters from

stratifying (layering)

C. Causes substrate particles (sand) to remain suspended.

I. Affects of Turbulence

II. Substrate

A. Definition - material an organism lives in or

on, including sand and rocks.

III. Tidal Zonation

A. Low-Tide Conditions1. 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

1. Composed of loose sediment that’s easily shifted by wind and

waves.2. Zones easily recognized3. Sandy beaches are the most familiar of tidal zones.

A. Sandy Beach

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 airc. Numerous seaweed species; algae

– more red and brown than greend. Animals: anemones, snails, sea

spiders, hydroids, sea stars, sea urchins, brittle stars, andsea cucumbers .