1. Rocky Seashores
2. Tides
3. Waves
4. Biota
5. Rocky Shore Ecology
6. Trophic Structure

Erosional Coastal Features

1. Erosional features are produced by the removal of coastal material.
2. Cliffed coasts are produced by wave erosion and their backshores are littered with debris which is either retained or carried away.
3. Shore platforms are gently sloping foreshore features of erosional coasts.
4. Stacks are residual cliffs separated from the shore.
5. Caves and arches can be eroded in cliff faces.

Effects of Waves

1. Surf zone surge
2. Crushing organisms
3. Dislodging organisms

Exposure to Waves

1. Organisms that live on entirely unprotected, surf-swept shores (convex shores with fairly deep water close offshore) must be able to withstand full exposure to waves and currents.
2. Organisms that live on semi-sheltered coast and open bays, where the force of the surf is somewhat dissipated (shores protected by a headland, a close-lying island, a reef of submerged rocks or a gradually sloping bottom) benefit from some exposure to waves and currents.
3. Organisms that live in sloughs, enclosed bays, sounds, and estuaries (concave shores with relatively small and often indirect openings to the sea) enjoy the ultimate in wave protection but often must be adapted for life in sandy or muddy environments.

Substrate Stability

1. Large rocks provide stability and shelter from waves
2. Many sessile animals require attachment to stable substrate

Tides

1. Tides are periodic changes in the height of the ocean surface at a particular place set up by the gravitational effects of the sun and the moon in relation to the earth.
2. The height of the tide is often referenced to mean sea level.
3. The tidal height changes periodically falling (ebbing) to a low point called low tide (ebb tide) and rising (flooding) to a high point called high tide (flood tide).
4. The tidal range (amplitude) is the difference between high and low tide levels.
5. The rise and fall of the tide on a coast is measured by tide gauges.
6. Tidal characteristics are determined partly by the size and shape of the basin and their effects are strong in shallow and relatively enclosed ocean areas.
7. Some coastlines have semidiurnal tides: two high tides and two low tides each lunar day.
8. Some coastlines have mixed semidiurnal tides: the two high tides and the two low tides are not of equal heights. There is a higher high tide and a lower high tide and there is a lower low tide and a higher low tide each lunar day.
9. Some coastlines have diurnal tides: one high tide and one low tide each lunar day.

Tidal Fluctuations

1. Spring tides are the strongest tides. They occur shortly after new moon and full moon, when earth, sun, and moon are in alignment, and have combined gravitational effects.
2. Neap tides are the weakest tides. They occur shortly after half-moon (first and last quarter), when the sun and moon are at right angles in relation to the earth, their gravitational effects are opposed.
3. The average spring tidal range is approximately 2 meters (about 6 feet). It is exceeded in certain gulfs and bays, notably in the Gulf of California 9 meters (about 30 feet) and in the Bay of Fundy more than l5 meters (50 feet, the world's largest spring tide range).

Tides and Coasts

1. Tides are important in shaping coasts because they lead to regular changes in the level of the sea along the coast, and because currents are generated as the tide ebbs and flows.
2. A large tide range creates a broad inter-tidal zone where wave energy is dispersed in traversing a broad shore zone, facilitating sediment deposition and promoting the development of salt marshes.
3. A small tide range creates a narrow inter-tidal zone where wave energy is concentrated, facilitating cliff erosion and impeding the development of coastal marshlands.

The Intertidal Zone

1. The intertidal is the area of shore between the extent of the high and low tides. It is alternately covered and uncovered by the rising and falling of the sea.
2. The intertidal is generally divided into three segments. The supratidal fringe is wetted by the ocean but is for the most part above the level of high tides. The true intertidal is covered and covered by the tides each day. The subtidal fringe is only infrequently uncovered.
3. The subtidal is seaward of the intertidal and the supratidal is landward and beyond the reach of ocean water.

Abiotic Conditions in the Intertidal Zone

1. The intertidal has aspects of both marine and terrestrial environments
2. Exposure to air is often once or twice daily
3. Desiccation
4. Temperature Extremes

Exposure Gradient

1. Duration of exposure to the air increases landward
2. Tidal height determines degree of exposure
3. Many organisms have adaptations to retain water at low tide

Dominants

1. Mussels, Barnacles, Periwinkles and Rockweeds
2. Large numbers or biomass
3. Great importance to other community members

Diversity

1. High species diversity
2. Many tpyes of seaweeds, invertebrates and fishes

Community Development

1. Influenced by the exposure gradient
2. Percentage of rock surface covered by organisms increases seaward
3. Diversity increases seaward

Zonation

1. Bands of Organisms Parallel the shore (Stephenson & Stephenson)
2. Bands of organisms lie within zones of differing exposure
3. Upper Intertidal Zone- Periwinkles and limpets
4. Middle Intertidal Zone- Barnacles and mussels
5. Lower Intertidal Zone- Seaweeds, urchins, and anemones

Tolerance to Exposure

1. Limits of tolerance and areas of greatest abundance occur at different tidal heights
2. Critical Tidal Heights define the breaks between zones (Doty)
3. Upper Intertidal Zone- above high tide line
4. Middle Intertidal Zone- between mean sea level and high tide line
5. Lower Intertidal Zone- between low tide line and mean sea level

Biotic Conditions

1. Competition
2. Predation

Competition for Space

1. Space is limiting
2. Many organisms overgrow or undercut one another in a battle for space

Predation

1. Many marine predators
2. Invertebrates and Fishes

Competition and Predation

1. Influence on zonation patterns (Connell)
2. Upper limits set abiotically
3. Lower limits set biotically

Barnacle Distribution

1. Physical factors determine the landward extent of Chthamalus and Balanus barnacles
2. Barnacle Competition determines seaward extent of Chthamalus
3. Thais predation determines seaward extent of Balanus

Patchiness

1. Agregated distributions are common
2. Gregarious Settlement of larvae
3. Microhabitat differences in environment
4. Disturbance

Disturbance

1. Opens space for resettlement (Paine)
2. Succession follows on the open spots

Succession

1. Predictable transition from one temporary association of organisms to another leading finally to a long lasting association
2. Pioneer Stage --> Seral Stage --> Climax Stage

Ecology of Succession

1. Pioneer organisms facilitate their own replacement
2. Climax organisms resist replacement

Rocky Shore Succession in the Mid Intertidal

1. Bacterial film-->Algal films and turfs-->Brown algae and acorn barnacles--> Mussels and gooseneck barnacles

Logs Battering Shore

1. Clear organisms from spot resulting in succession
2. Each spot would be at a different stage of succession
3. Intermediate amounts of disturbance promote patchiness and increases diversity

Keystone Species

1. Importance to community out of all proportion to numbers
2. Removal would bring about major changes in community structure

Predatory Starfish

1. Pisaster as keystone species (Paine)
2. Pisaster prevents Mytilus from monopolizing space

Food Web

1. Diverse Sources of nutrition for primary consumers
   • Benthic Algae
   • Detritus
   • Plankton
2. Long food chains with many levels of carnivory