1. SOFT-BOTTOM INTERTIDAL COMMUNITIES
Intertidal – narrow fringe along the shoreline that lies between highest high tide and lowest low tide
AND
- Any bottom composed of sediment
- Where organisms can burrow easily
- In NA – dominate on east coast & Gulf coast

2. SOFT-BOTTOM INTERTIDAL COMMUNITIES
- regularly exposed to the air
- some wave shock
- changing air temperatures
- changing salinity
- desiccation (coarse sand)
- predation
- good food supply
Life “on the floor at the shore” is the most difficult marine environment due to lack of stability

3. ANIMAL ADAPTATIONS
Low Oxygen
- pump oxygen through siphons or burrow
- have hemoglobin
- Soft Substrate
- burrow
- eat their way through
- small – live in interstitial water
- Feeding
-deposit feeders – take advantage of abundant detritus
-suspension feeders – take advantage of detritus settling
-predators – moon snails, birds, fishes nibble

4. FYI - No two beaches have the exact same sand
FYI - No two beaches have the exact same sand. From the red sand of Prince Edward Island to the sugary, white sand of Siesta Key, Florida to the jewel-like pebbles on some Hawaiian beaches, sands have an amazing variety of color and texture.

6. Sand is constantly in motion and so zonation is less distinct than a rocky shore. Beach zonation is determined by daily tides.
Not much zonation in muddy bottoms.
1. Supratidal - upper beach area where materials are stranded by high tide (strand line).
Because sand contains little food, scavengers must search along the strand line for beach wrack (decaying organisms).
Inhabitants adapt by burrowing to reduce abrasion and escape the heat and predators.
ex: clams, sand fleas, ghost crabs, insects, reptiles, and rats

7. 2. Intertidal - area from high to low tide; least stable area with the highest diversity of life.
The sand is wet by the capillary action of evaporating water.
ex: cord grass, bacteria, phytoplankton, worms
3. Subtidal - always just under water; most stable surface
ex: eel grass, crab, shrimp, sand dollars, flounders, molluscs

8. In the winter, high energy waves erode the beaches pulling sand back into the sea.
Summer waves are weaker and deposit sand on the beach (foreshore) where dunes can form.
Dunes occur throughout the world but are largest on coasts with a wide continental shelf to supply the sand to build dunes

9. Succession of dune communities follows this pattern:
1. Pioneer: Winds blow sand off the beach where it is trapped by sea grasses.
Their roots stabilize the sand and dunes begin to form.
NOAA
Sea grasses are protected by law.

10. The windward dune face usually has a gradual slope, while the leeward side is steep - (called a berm). It prevents land breezes from blowing sand back into the ocean.
2. Juvenile: Behind the dune, is the swale - a low area where breezes are deflected and the result is furnace-like temperatures.

11. Birds build beaches and dunes!
3. Mature: Secondary dunes form behind the swale. They are vegetated with woody shrubs and eventually a maritime forest develops.
Beaches are protected by the dune. Dunes are held in place by grasses. Grasses come from seeds deposited by birds feeding and nesting on the shores.
Birds build beaches and dunes!

12. Clam Dissection