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High energy shoreline habitats

I. Sandy beach

A. Conditions

1. Temperature

2. Water availability
   a. Tidal variation in water level
   b. Lack of fresh water

3. Wave action
   a. Pounding the habitat
   b. Grains of sand can scour organisms

4. Lack of a firm foundation

5. Survival strategies – many organisms live beneath the surface

B. Upper beach – supratidal – high tide to dunes

1. Conditions – hot sands, dry, little access to fresh water, no protection from wind and spray, no place to hide from predators

2. Organisms
   a. Ghost crab (crustacean) – hide in burrow, must leave to feed, fast
   b. Amphipods (crustaceans)- beach hoppers/beach fleas, scavengers
   ** both keep gill wet with a thin layer of water – breathe air.

C. Strand line – delineates point of highest tide
Lots of organic material piled hear many organisms come here to feed – amphipods, insects, birds

D. Intertidal – between high and low tides

1. Conditions – pounding of wave action, alternate flooding and dessiction

2. Interstitial sand community – living among the sand grains in the water held by capillary action
   a. bacteria
   b. producers; dinoflagellates and diatoms
   c. consumers; protozoa, copepods, rotifers, annelids (build sand tubes)
   d. nematodes – 70% of consumers, simple unsegmented worms with a proboscis

3. Macroscopic organism
   i. mole crabs – (Emertia) – migrate with tide, feed with specialized antenna
   ii. clams – hold in place by burrowing
   iii. sandpipers, etc.
   iv. visitors– grunions, horseshoe crabs, etc.

E. Lower beach – subtidal – below the low tide

1. Conditions – more moderate – temp etc. doesn’t change as much, still wave action& no solid footing

2. Organisms – on or under bottom
   a. Echinoderms – sand dollar: grazer and filter feeder (on edge)
   b. Gastropods – conchs, moon snails
   c. Crustaceans – blue crab (Callinectes) lady crab (Ovalipes)
   d. Horseshoe crabs
   e. flounder, skates, rays

II. Rocky intertidal zone – characterized by horizontal bands of zonation

A. Conditions

1. High tide – wave action

2. Low tide – dessication, temperature extremes, salinity changes

3. Organisms must attach to firm substrate rather than burying themselves
   - leads to fierce competition for space
   - and vertical zonation

B. Upper intertidal zone – extends from just below the high tide line to above the high tide line (supratidal, the splash zone).

1. Black zone - upper region of UIZ – dominated by blue-green algae and lichens.
   Blue-green algae – protected by slime layer
   Lichens – fungal hyphae hold water

2. Littorina region – bottom end of the UIZ – dominated by periwinkles grazing on algae with their radula
   a. Different Littorina species live at different heights
   b. Limpets also found grazing here
   c. Amphipods (compressed) and isopods (depressed) found in Enteromorpha blooms

C. Middle intertidal zone – (intratidal) between the tides, exposed regularly, for a shorter period at the bottom the zone

1. Top region – dominated by Balanus (acorn barnacles)
   a. can withstand wave punishment – shape and method of attachment
   b. Lower intertidal zone
   c. Life cycle – pelagic nauplii, cypris settles, adult sessile (allows spread of species)
   d. Zone width: upper end determined by dessication, lower end determined by predation (welks and starfish)

2. Middle region – dominated by Fucus (rockweed)
   a. Can withstand dessication due to slime layer
   b. Low tide - Wet fronds cover and protect many more sensitive organisms (amphipods, isopods, hydroids, tube worms, etc.)
   c. High tide - like a forest
   d. zone width – dessication at top, competition at both ends

3. Lower region – dominated by Mytlius (mussels)
   a. Can withstand dessictation by closing shell
   b. Held in place with byssal threads – can move slowly
   c. Streamlined shape reduces effect of waves
   d. Life cycle – planktonic veliger larvae
   e. Limitation of zone width – dessication at top, predation at bottom

D. Lower intertidal zone – (subtidal) begins at low tide line, only exposed during extremely low tides, waves and severe currents dominate the area

1. Great diversity – conditions not as harsh, lots of organisms can live here: hydroids, bryozoans, nudibranchs, echinoderms, annelids, crustaceans (crabs, skeleton shrimp, lobsters), tunicates, sponges

2. Substrate covered with dense growth of algae (protect organisms during extremely low tides)

3. Echinoderms most conspicuous and have a great impact de to predation (sea star, anemone) or herbivory (urchin) – cannot long survive exposure

III. Tidal pools

A. Conditions – depend on size, depth and location

1. Temperature fluctuations

2. Salinity fluctuations (due to evaporation)

3. Dissolved oxygen fluctuations
   a. Used up – especially at night
   b. Solubility – decreases w/ increasing temp.

B. Size, depth, location

1. Size – larger take longer to heat, etc

2. Depth – as above for size, also may have great volume with reduced surface area, heats more slowly

3. Location – higher up in the intertidal zone is exposed for longer periods of time

C. Organisms

1. You will find organisms from zones further down the intertidal zone because they are protected from dessication (and maybe predation).
   i.e. anemones

2. Steno- (haline, thermic) Echinoderms – sensitive to changes, found only in large, deep pools.

3. Eury- Specialized organisms – tide-pool sculpin, etc.

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