8- tides and rocky intertidal

other than subduction, how do rocky shores develop?

glacial retreat

rocky intertidal is stressful

1. physical stress

2. biological stress

3. chemical stress

physical stress

- submersion/exposure

- waves energy

- temperature extremes

biological stress

- space

- competition

- predation

chemical stress

salinity extremes

exposure stress

1. struggle to breath

2. desiccate

wave shock stress

1. Abrasion by particles

2. Hydrostatic pressure from breaking waves

3. Drag from flowing water exerts additional force

controls populations from getting too large

exposure stress gradient

1. spray zone

2. high tide zone

3. middle tide zone

4. low tide zone

how is stress involved in distributions?

puts species in an optimal range due to a balance of abiotic and biotic stress

zonation of rocky intertidal

1. upper intertidal: lichens, periwinkles

2. middle intertidal: barnacles and mussels

3. lower intertidal: seaweeds and surf grasses

conclusions from Connell Experiments

1. Predation is important in lower intertidal

2. Biological factors control lower limit of

species occurrence

3. Physical factors control upper limit

4. Community structure a function of very local processes

how do predators affect community structure?

- sea star, barnacles, and mussels example

- sea stars promote coexistence

- sea stars prefer whatever is most abundant